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United Presbyterian 3fag . . .178 Coal Formation or Coal Measures, . . . . . . . . 179 North Staffordshire Coal Field, . ... . . . .194 Cumberland Coal Field, 194 Coalbrook Dale Coal Field, -. . . .196 Carboniferous System of Scotland, ...*.... 202 Carboniferous System of Ireland, 205 Carboniferous System in Foreign Countries, . .... 208 General View of Circumstances under which the Coal Beds were Deposited, . 210 Convulsive Movements of the Carboniferous System, 221 List of Organic Remains of the Carboniferous System, 226 Figures of Carboniferous Fossils, 234 PERMIAN SYSTEM, 245 Range of the Permian System in England, 248 Permian System of Europe, 251 Remarks on Certain Members of the Permian System in England, . . 252 List of Organic Remains of the Permian System, 255 Figures of Permian Fossils, 258 General Conclusions concerning Primary Strata, 260 CHAPTER IX. LOWER MESOZOIC STRATA, 263 Circumstances attending the Origin of the Saliferous System, . . . 271 Organic Remains, 273 Table of the Organic Remains of the Saliferous System, .... 275 Figures of Lower Mesozoic Fossils, 279 CHAPTER X. MIDDLE MESOZOIC STRATA Disturbance of the New Red Series, . .281 Oolitic System, 282 Lower Oolite Formation, 292 Section of Brora, 299 North-East Coast, Isle of Skye, 299 Middle Oolite Formation, 304 Upper Oolite Formation, 310 Wealden Formation, 313 Oolitic System Foreign Localities, 313 Disturbances of the Oolitic System, 322 Organic Remains of the Middle Mesozoic System, ..... 324 Figures of Lias Fossils, 334 Figures of Lower Oolite Fossils, 339 Figures of Middle Oolite Fossils, 343 Figures of Upper Oolite Fossils, 346 Figures of Wealden Fossils, 348 CONTENTS. XI CHAPTEK XL E UPPER MESOZOIC STRATA Cretaceous System, 350 Range of the Cretaceous System out of England, 359 Dislocations of the Cretaceous System, ........ 362 Organic Remains of the Upper Mesozoic System, 364 Figures of Chalk Fossils, 373 Figures of Lower Green Sand Fossils ........ 377 Figures of Gault Fossils, 379 Figures of Upper Green Sand Fossils, 379 CHAPTER XII. CAINOZOIC STRATA, 380 Eocene Deposits, 385 The London Clay, 386 Bagshot Sand and Bracklesham Beds, . . . . ".'.."' .387 Barton Clay Group Headen Hill Group, St. Helen's Beds Bembridge Beds Hempstead Beds, List of Organic Remains of Eocene Fossils, . Figures of Eocene Fossils, 388 389 390 399 MEIOCENE STRATA, . 401 CHAPTER XIII. PLEIOCENE STRATA Crag, . . . . 402 List of Organic Remains of Pleiocene Fossils, . . . . . . 404 CHAPTER XIV. PLEISTOCENE DEPOSITS, . . . . . . : . . . . .408 Ossiferous Caverns, . '" . ...... . . .411 Glacial Deposits, . . . . . . , '. . . .419 Post-Glacial Deposits, . . . .430 Organic Remains of the Pleistocene Period, 431 Genera of Pleistocene British Fossils, 439 Table of Remains of Mammalia in Caverns and Superficial Deposits, . . 442 Dislocations of the Tertiary Strata, 444 Foreign Tertiary System, 446 Examples of Organic Remains of Lacustrine Tertiaries, .... 463 CHAPTER XV. DEPOSITS OF THE MODERN ERA MODERN CAUSES IN ACTION, . . . 466 Wasting Effects of the Atmosphere, 468 Descending Streams and Rivers, ......... 475 Nature of Deposits in Gulfs, Estuaries, &c., . 485 Sea Action, Erosive and Transporting, 489 CHAPTER XVI. ROCKS PRODUCED BY THE AGENCY OF HEAT, 493 Granitic Rocks, 494 Arran, description of, . . . 503 Felspar Porphyry, 511 Syenite, 513 Hypersthene Rock or Hypersthenic Syenite, 515 Gabbro, Granitone, Euphotide, Diallage Rock, Serpentine, .... 516 Greenstone, '. 517 Basalt, 519 Melaphyre, Pyroxenic Porphyry, 524 Claystone Claystone Porphyry, 525 Amygdaloidal Trap, 525 Xll CONTENTS. RIM Wacke, 526 Pitchstone, 527 Trap Tuff Porphyritic Breccia Volcanic Sandstone, 528 CHAPTER XVII. MINERAL VEINS, 529 Substances in the Veins, . . . '..' . . . . . .530 Mode of Aggregation of the Ingredients, 532 Relations of Veins to each other, . .;'*.'. . . . . 536 Geographical Relation of Veins, 541 Connection of Fissures and Main Joints, ....... 543 Relation of Mineral Veins to the Hocks which enclose them, .... 544 Relation to the Different kinds of Rocks, 544 Walls of a Vein, 547 Relation to the different ages of Rocks, 548 Relation to the local centres of Igneous Action, . . . . . .551 Electricity of Veins, 552 CHAPTER XVIII. VOLCANOES AND EARTHQUAKES, ... 555 Earthquakes, 560 Thickness of the Crust of the Earth, 563 DISTURBANCES OF THE STRATA, 565 Geological periods of Convulsion, 565 Direction of Convulsive movements, ........ 575 Direction of the Strata, 578 Effects of Convulsions in altering the relations of Land and Water, . . 579 Effects of Convulsions on deposition of Strata and on Organic Life, . . 590 Mineral Characters of the Systems of Strata, 591 Successive races of Marine Animals, ........ 593 Fresh water and Marine alternations, 594 The Weald of Sussex 594 Hopkins on the Weald, 597 CHAPTER XIX. PERVADING EFFECTS OF HEAT, 599 Consolidation and Alteration of Stratified Rocks, 601 Metamorphisin of Rocks, 602 Atmosphere, 612 CHAPTER XX. STATE OF GEOLOGICAL THEORY, 615 Lapse of time Geological Chronology, ....... 616 Successive conditions of the Globe, 625 Successive conditions of the Materials of the Crnst of the Globe, . . .630 APPENDIX. TABLES AND CALCULATIONS, 635 Physical Relations of the Globe as a part of the Solar System, . . .635 Temperature of the Globe, 636 Thermometrical Scales, 638 The Barometer 639 The Aneroid Clinometer, 641 Zones of Life in the Sea, 645 Constituent Ingredients of Rocks, ........ 646 GLOSSARY, 649 INDEX, - 661 GEOLOGY. CHAPTER I. PEOGEESS OF THE SCIENCE. Objects and Scope of ecology. The term science, as now employed, is understood to express, not only the body of information collected, general laws established, or system. recognized in any department of human knowledge, but also the ultimate objects and whole scope of the research. Strictly speaking, perhaps, the former is its legitimate meaning. Thus the science of optics or of acoustics properly sig- nifies the body of information acquired and the generalizations estab- lished in those branches of human study, but is popularly understood, by way of anticipation, to include indefinitely the expected or possible future accessions of knowledge on the subject. It is in conformity with this ordinary language that we shall endeavour to give the definition of geology ; for though truly none of the sciences of observation has made more remarkable progress toward successful generalization than this, yet the prospect of further discovery is so much richer than the retrospect, and the activity and talent employed in the research is so much on the increase, that we can hardly offer too bold and expanded an expression for the ultimate aims of geology. It might provoke a smile to recount the singularly contracted notions on this subject which have till lately figured in works on geology. The history of the deluge, the discussion of the character and repositories of minerals, the classification of fossils, the effects and causes of volcanoes, belong indeed to this comprehensive subject, but these and many other important inquiries are only particular branches of the great study of geology. One cause of the inadequacy of the definitions usually presented probably not confined in its application to any one of the sciences of observation is the difficulty of foreseeing, in the early stages of a new study, the direction and extent of its future development. Mathe- 2 PROGRESS OF THE SCIENCE. matical science, founded upon the pervading idea of relative magni- tude, may by this comprehensive definition, anticipate all the various determinations concerning number, proportion, and direction, which are daily added to its stores, and which are, in fact, the developments of recognized fundamental axioms ; but the natural sciences have a different mode of unfolding themselves, and it is only after they have made great progress, and many detached inferences, drawn 'from still more scattered data, have been combined into system, that the most able cultivators can clearly discern whereto their labours eventually tend. Definition. Guided by these views, we shall define geology as that science to which it is allotted to investigate the ancient natural history of the earth ; to determine by observation what phenomena of living beings or inorganic matter were formerly occasioned on or within the globe, in what order and under what conditions ; to em- ploy the comparative data, which are furnished by investigation of the present operations of nature, in characterizing and measuring the successive revolutions which the earth has undergone before arriving at its present state ; and thus, finally, to furnish a complete historical view of the conditions which have regulated, and of those which do regulate, its system of mechanical, chemical, and vital phenomena. From the terms of this definition we may at once understand why, in former times, the most able men erred so grievously in their attempts to elucidate the history of our globe ; for, while geography was imperfectly known, before commerce and the knowledge of lan- guages had made us acquainted with the productions and traditions of every clime, before the birth of most branches of physical science, it was impossible to accumulate the numerous and exact data from which alone geology takes its origin. And since the general truths of geology are made apparent only by the application of the known laws of modern nature, it is evident that, before the discovery and estabh'shment of those laws, the wisest of the old philosophers had nothing to substitute for enlightened theory but arbitrary hypothesis and fanciful conjecture. These are the reasons why the ancient doctrines concerning the world are almost without exception be- wildered with the impossible problem of the creation of matter, and buried in a chaos of subtle inventions. Speculative Geology. Cosmogony, not geology, is the subject of the old traditions of Phoenicia, Chaldgea, Egypt, and China ; and the same incurable fault springs up again and again among every people, in every period, always with the same injurious effect. The modern fictions are not better or more probable than the old ; none more remarkable than the cosmogony of the Babylonians which caught the attention of Niebuhr. According to it, the world began with a chaotic darkness, which was a fluid, and inhabited by swimming ani- SPECULATIVE GEOLOGY. 3 mals, of the strangest forms. Representations of them are said to have been preserved in the temple of Belus. When light appeared these animals hardened and died. Ingenious Greece added a considerable refinement in the nature of the fictions by which it was sought on vague analogies to supply the want of fair inductions. The Epicurean doctrine of atoms, and the primary elements of Aristotle and Pythagoras, are inventions of a different order from the Egyptian " Egg of the World," and the primeval monsters of Chaldsea. Familiar with countries in which earthquakes were frequent, and volcanic eruptions not unknown, they quickly gathered right though vague impressions of great revolutions in nature, indulged the ideas of frequent changes in the relative ex- tent of land and sea, and supported this doctrine by reference to his- torical facts concerning subsidence and elevation of land, to the occur- rence of marine shells far from the sea, and to the ordinary processes of change, decay, and renewal in physical phenomena. What Herodotus says regarding the sediments deposited by the Nile in the valley of Egypt, and carried out to sea ; of the time (10,000 or 20,000 years) which he estimates as sufficient for the Nile, if diverted into the Erythraean sea, to fill up that long gulf ;* and of the shells found on the hilly borders of Egypt which testified to its former submersion beneath the sea, may be quoted with appro- bation as a fair specimen of ancient observation and inference, f In the pages of Aristotle such local, truths assume the more im- posing aspect of general propositions, involving frequent displace- ments of land and sea, periodical revolutions, and systematic changes at every point, but still preserving a constant sum of natural powers and effects. J These were also Pythagorean ideas, they were the basis of the system of Epicurus, || and in some form or other they are always recurring ; the natural fruits of analogical reasoning : Sic rerum summa novatur Semper. In precise appreciation of the phenomena, the geographer Strabo appears to have far outstripped his predecessors ; he distinctly alludes to the various explanations of the phenomena of marine remains, proposed by Eratosthenes, Xanthus, and Strato, and adds his own view of the matter, in terms not very different from those employed at the present day by the advocates of the gradual elevation of our solid land from the bed of the sea. The ten centuries of war and commotion which succeeded the " Her. ii. 11. ty-tu ftiv tXtroftKi yi X.K.I [Avqttav IVTO( ^atrO^vKi etv f Her. ii. 12. tiuv ti ryv AiyvxTov rr^cxnutw^ TK iyo(jt.-M^ yJ? , xoy%uXiKi TI Q/xivcfA-Kx, art rottrt ev^io-i. The shells were, perhaps, truly "fossil," and belonged to the rocks in the hilly ground. J Aristotle, Mcteorologica. Ovid, Metam. XV. expounds the system of Pythagoras as it was understood at Rome. tl Lucretius unfolds the philosophy of Epicurus with the zeal of a disciple poet. 4 PKOGKESS OF THE SCIENCE. destruction of the Western empire, were less favourable to the growth of physical science than even those which had preceded ; and while all the learning of the world was shut up in cloisters, and confined to one class of society, we cannot wonder that the grand cosmogonies of the ancients should have dwindled into puerile discussions. Learn- ing was in chains, but it was nevertheless spread abroad through Christendom, and waited but for the extension of geography and commerce, by the maritime discovery of India and America, to be emancipated from its thraldom ; and for the discovery of the art of printing to be excited to energy and enthusiasm, by the physical and astronomical discoveries of Kepler and Galileo. It was not, indeed, till the inductive philosophy, budding in Gralileo, blossoming in Bacon, and rich with fruit in Newton, had been widely disseminated among mankind, that we were entitled to look for fixed data and limited generalizations in any branch of natural science. The diffusion of this mode of philosophizing may be said to have withdrawn the veil of prejudice which had previously obscured the visible creation, and to have really generated the sciences which treat of the properties of matter and the phenomena of life. Origin of inductive Geology. Four different classes of phenomena have conducted men of observation to a partial acquaintance with the stratification of the crust of the earth. 1. The effects of disturbance in countries shaken by earthquakes and marked by periodical volcanic excitement as Asia Minor, Italy. 2. The arrangement of the various soils in England. 3. The appearances of regular structure in the mines of Germany, Sweden, &c. 4. The remains of plants and animals entombed in the strata of England, France, Switzerland, Germany, Italy. 1. Of the first class of observers, the most distinguished in early times is Strabo, who gives an interesting account of the Katakekau- mene, (burnt district), in the valley of the Hermus, in Asia Minor, a district which remained almost un visited till Mr. Hamilton re- newed our acquaintance with its remarkable features, so similar to those of Auvergne. The great cone of Etna caught the attention of the Greek philosophers and poets the deep-seated source of its fires their origin and decay. For this great mountain neither Ighea semper erit, neque enim fuit ignea semper. And the phenomena connected with Vesuvius, which fatally stimu- lated the curiosity of the elder Pliny, have trained up in modern times philosophic men like Steno* and Lazzaro Moro,t who not only per- ceived succession of time in the deposition of the strata, but great physical changes displacements of land and sea affecting large * De solido intra solidum, &c., 1669. f De Crostacei, &c. f 1740. LISTEE PACKE. 5 areas of country. It is in this school that we find the germs of our modern theories of elevation and depression of land, whether by the united and sudden violence of excited heat, or the gradual effort de- pending on a general change of dimensions or temperature of the globe this being the Leibnitzian theory.* 2. Agriculture. The early advancement of agriculture in a country so populous, and of so diversified an aspect as England, necessarily produced a very intimate knowledge of different soils ; and as these depend on the nature of the substances beneath, which range in regular courses, it is not surprising that maps of the soil should have been early proposed by agriculturists. Dr. Lister, residing in Yorkshire, where the ranges of soil are very well defined, was the first to propose to the Royal Society, in 1683, a map of the soils of England. " We shall be better able," he says, " to judge of the formation of the earth, when we have duly examined it, as far as human art can possibly reach, beginning from the outside downwards. And for this purpose, it were advisable that a soil or mineral map, as I may call it, were devised. The soil might either be coloured by a variety of lines or etchings ; but great care must be taken very exactly to note on the map where such and such soils are bounded. As for example, in Yorkshire, the woolds, (wolds.) chalk, flint, and pyrites, &c. 2. Blackmoor, moors, sandstone, &c. 3. Holderness, boggy turf, clay, sand, &c. 4. Western mountains, moors, sandstone, coal, iron- stone, clay, sand, &c. Nottinghamshire, mostly gravel, pebble, clay, sandstone, hall-plaster, or gypsum, &c. Now if it were noted how far these extended, and the limits of each soil appeared on a map, something more might be comprehended from the whole and from every part, than I can possibly foresee, which would make such a labour very well worth the pains. For I am of opinion such upper soils, if natural, infallibly produce such under minerals, and for the most part in such order. But I leave this to the industry of future times." This scheme was partly executed by the county reports presented to the Board of Agriculture, the earliest of which dates from 1794 ; but the investigation being usually unconnected with sound views of the interior conformation of the earth, few of these detached efforts led to any important results. Packe, in his Chorographical Chart of East Kent, (1743), has shown what admirable general views of the physical geography and leading rocks of a district may be entertained, without that combination of results which leads to geology. 3. mining. Miners in every period must have been acquainted with the order of succession of the rocks through which they seek the treasures of coal and metal ; and in a tract consisting of alter* * Protogsea, 1680. 6 PEOGEESS OF THE SCIENCE. nating coal-seams, limestones, sandstones, and shales, as at Aldstone Moor, in Cumberland, the range and extent of the different strata must always have heen familar to the workmen. There must therefore always have been a MINEEALOGICAL SCHOOL OF GEOLOGY in every country in which rich subterranean treasures attracted the attention of mankind. Agricola embodied the floating information of the miners of Saxony as early as 1546 ; (De Naturd Fossilium ;) he was followed by Cordas, Gresner, Kentmann, Fabricius, Encelius. " not unworthy of praise," as we are told by Baier, (Oryctographia Norica,) 1708. Sweden, equally celebrated for its mines, produced, between 1730 and 1762, five com- plete systems of mineralogy, including the methods of Linnaeus, Wallerius, Swab, and Cronstedt. Linnaeus* makes known the series of strata in a part of Sweden ; the passage is remarkable : 1 infimum e Cote. 2 secundum e Schisto. 3 tertium e Marmore, nidulantibus petrificatis pelagicis saepe etiamnum peregrinis. 4 quartum e Schisto. 5 supremum e Saxo rupestri, saepe vastissimo. Compare with this the well-known sequence of Swedish Lower Silurian strata in the Kinnekulle, as given by Murchison in his latest work :f there is no difference : a (1) Lowest or fucoid Sandstone. b (2) Alum slates. c (3) Orthoceratite Limestone. d (4) Black graptolite Schists. e (5) Eruptive Greenstone. Those works are principally devoted to a description of the most prominent minerals, and it is only incidentally that we gain from them proofs of the considerable, though detached information which the authors really possessed concerning the manner in which min- erals constitute, by their assemblage, the crust of the earth. In 1750, however, Tylas, a Swede, and in 1756, Lehmann, a Ger- man, broke through the fetters of a mere mineralogical method, and by proving a regular order of superposition among stratified rocks, opened the way to the sagacious generalizations of Werner and the cautious inductions of Saussure. Werner. A peculiar set of opinions concerning the formation of the earth, has been honoured by the title of the Wernerian theory ; and the pupils of Werner who had found proof of the truth of his practical rules and inferences, may be readily pardoned for the deter- * Systema Naturae. Regnum lapideum, 1770. t Siluria, p. 318. LHOTffiUS WEENEE. 7 mination which they have shown to uphold the hypothetical notions of their master. But if we wish to ascertain the real value of the benefits which the researches of Werner have conferred upon geology, we must forget his theory, and view only the data which he collected for its foundation. Werner was educated amidst the mines, and in the society of the most eminent mineralogists of Saxony ; their experience and their opinions became his own, and doubtless swayed and directed the energies of his mind. To judge from his own works, and from the course which his pupils have so long pursued, the principal point of view under which Werner contemplated the rocks and metallic veins of Germany, was the relative period of their production. Lehmann had, indeed, b taken the same course, and already distinguished primary and secondary rocks, the former (a) existing in moun- tain chains, mostly stratified at high angles of declination, and devoid of organic remains, the latter (6) disposed more horizontally, and stored with the reliquiae of life. But Werner, with of I characteristic tact and boldness, applied this method // of investigation to every case, and took it as the basis 1 ~ri of his classification of rocks. // Basis of his System. " When two veins (a b) cross, 2 and one of them (b) cuts through the other, (a,) the one which is divided (a) is the more ancient." Among stratified rocks superimposed on one another, the lower members of the series, those which lie nearest the centre of the earth, were deposited first, and the relative antiquity of the different strata is exactly in the order of their position. Thus c is the oldest rock of the series, c, d, e, f, g. By this manner of proceeding in the instance of the Harz moun- tains, Werner was enabled to frame a system or classification of rocks in the order of their respective position as far as ~ g could then be ascertained, and consequently in the / order of their consecutive formation. Thus the - Brocken Mountain was described by Werner and - his followers as a central cone of granite, upon " ~~B which on all sides round were laid various other rocks in a certain and constant order of succession ; as granite, clay-slate, limestone, greywacke and greywacke-slate, old red sandstone, limestones, gyp- sums, sandstones and limestones ; the upper and newer strata having their outgoing or terminal edges lower and lower continually. Werner presumed that this order of succession among these rocks would be found to prevail in all parts of the world, and thus an- nounced a grand principle in the construction of the earth which was destined to have a most beneficial effect on geological theory and 8 PKOGKESS OF THE SCIENCE. observation. For, on the one hand, it dissipated the chaotic dreams of those who maintained that the whole crust of the earth was to be viewed as a mass of sediment from the waters of " the deluge ;" and on the other, exhibited the most important subject of inquiry respect- ing the constitution of the earth, and fixed a precise method of in- vestigating it. Extending his views through other parts of Germany, Werner completed the following system of successive formations. (Jameson) . "Werner's Series of Formations. The lowest and oldest series of rocks discoverable by examination is supposed to be of crystalline origin, to be devoid of organic remains, and to have been originally, as at present, stratified at high angles of inclination. These are called by Werner Primitive Rocks. Such are : Granite, Porphyry, Gneiss, Syenite, Micaceous schistus, Topaz rock, Argillaceous schistus, Quartz rock, Primitive limestone, Primitive flinty slate, Primitive trap, Primitive gypsum, Serpentine, Eurite, or whitestone. A second series of rocks appearing to be partly of crystalline and partly of mechanical origin, containing some remains of plants and animals, with slopes of stratification less remarkable than the former, is named by Werner, on account of these intermediate characters, Transition Eocks. Transition limestone, Greywacke, Transition trap, Transition flinty slate. The third series consists of strata more decidedly of mechanical aggregation with abundance of organic exuviae, and from the greater frequency of these strata in the flatter regions of the globe, where their planes of stratification are nearly level, they are called Flcetz (flat lying) Eocks. ] st or old red sandstone. 3d sandstone, or quadersandstein. 1st floetz limestone. 3d limestone, or planerkalkstein. 1st floetz gypsum. Flcetz trap. 2d variegated sandstone. Independent coal formation. 2d floetz gypsum. Newest floetz trap. 2d floetz limestone, or muschelkalkstein. Lastly, various sandy and argillaceous strata, imperfectly known to Werner, but since ascertained to contain the whole vast series of tertiary strata, are included by him under the title of alluvial That this classification is partly erroneous in principle, and in all MITCHELL WHITEHURST. 9 respects incomplete and inadequate to the rigour of modern investi- gation, is apparent at a first glance, but it obviously contains the essence of rightly planned arrangements, viz., a determined reference to the antiquity of the deposit. Werner is, therefore, entitled to the distinguished praise of clearly announcing and striving earnestly to establish one of the most important general laws yet ascertained re- specting the structure of the earth. He proved that in a particular district its stratified rocks are laid one on another in a certain order of succession, and affirmed that the same, or a very similar order, prevailed over large parts of the earth's surface. Mitchell. It has been usual, especially in England, to quote a variety of persons before the date of Werner, to whom the honour of first declaring the principles developed by the professor of Freyberg might with more justice be ascribed. The nature of his obligations to his own countryman, Lehmann, has been already sufficiently stated. Mitchell, one of the ablest of the natural philosophers of England during the middle of the 18th century, who, for a short time, filled the Woodwardian chair of geology at Cambridge, and afterwards resided in Yorkshire, had certainly made himself acquainted with the series of English strata, especially in the northern counties, and had even gone so far as to discover some of the most important general relations between the geological structure and the physical features of the globe, defining with a masterly hand the mutual dependence of mountain ranges and lines of stratified rocks. . In frequent journeys between Cambridge and Yorkshire, mostly performed on horseback, he composed a useful section of the strata between the chalk hills of Bedfordshire and the coal strata of Not- tinghamshire. Habitually communicating information of this kind to his friend Cavendish, Mitchell never printed an account of his discoveries ; the great chemist verified, but never mentioned them ; they lay concealed among the Cavendish MSS. and neglected on the back of an old letter of Smeaton, till, in 1810, the letter was seen by Farey ; and, in 1844, the papers in the possession of Lord Burlington disclosed many unexpected facts in the history of his great kinsman.* Whitehum. The merit of Whitehurst, also, both as a theorist and as an observer, is very considerable. He states the object of his work,f published in 1792, to be " to trace appearances of nature from causes truly existent ; and to inquire after those laws by which the Creator chose to form the world ; not those by which he might have formed it, had he so pleased." His mode of proceeding is exactly in conformity with the first clause of this sentence ; for his whole work is a finely woven web of plausible deduction and conjecture, founded on general physical considerations, and supported or illustrated by a * See this subject examined in Phillips's "Life of William Smith, LL.D." t The Natural History of the Earth, by John Whitehurst. 10 PROGRESS OF THE SCIENCE. selection of corresponding facts and observations. This inverse pro- cess is certainly, in many respects, characteristic of a cabinet geologist, and yet the volume contains abundant proof, that its author was both well acquainted with a great variety of important data in geology, and possessed of sufficient generalizations to develop their value. What is stated by Whitehurst concerning the succession of strata in Derbyshire and other parts, was chiefly derived from the miners and colliers, who, certainly, for a hundred years before the dawn of sound geology, knew perfectly the almost invariable sequence of strata in their own districts. Saussure. The value of Saussure's distinguished services to clear the way for legitimate inductions in geology cannot be better ex- pressed than in the following passage of Cuvier, wherein he is com- pared with Werner : " En effet, la partie purement mine'rale du grand probleme de la theorie de la terre a ete fetudiee avec un soin admirable par De Saussure, et portee depuis h un deVeloppement e"tonnant par Werner et par les nombreux et savans eleves qu'il a forme's. " Le premier de ces hommes celebres, parcourant peniblement pen- dant vingt anne"es les cantons les plus inaccessibles, attaquant en quelque sorte les Alpes par toutes leur faces, par tous leurs defiles, nous a devoile tout le de"sordre des terrains primitifs, et a trace plus nettement la limite qui les distingue des terrains secondaires. Le second, profitant des nombreuses excavations faites dans le pays qui possede les plus anciennes mines, a fixe les lois de succession des couches ; il a montre leur anciennete" respective, et poursuivi chacune d'elles dans toutes ses metamorphoses. C'est de lui, et de lui seule- ment, que datera la geologic positive, en ce qui concerne la nature minerale des couches : mais ni Werner ni De Saussure n'ont donne a la determination des especes organiques fossiles dans chaque genre de couche, la rigueur devenue necessaire, depuis que les animaux connus s'elevent a un nombre si prodigieux."* 4. Inductive Geology principally founded on the Organic Reliquiae. The grand fact upon which, in modern times, geological inquiries have hinged, the occurrence of marine animals far from the sea and deep in the solid bosom of the earth, was so far understood by the ancients, that they had ascertained the general agreement of fossil and recent marine shells, nor does there appear the least trace of doubt on this subject in their writings. But warm discussions arose concerning them among the naturalists of Italy, and at a later period, those of France, England, and Germany, countries in which marine exuviae are particularly plentiful and various. The 16th century was wholly wasted in the ridiculous dispute whether the fossil shells were genuine marine exuvia?, or mere lusus * Ossemens Fossiles Disc, prelim. SATJSSTJRE LLWTD WOODWAED. 11 natures produced by a plastic power or fermenting fatty earth ? and the question assumed a more difficult character from the addition of another, whether, if they were genuine petrifactions, they were all deposited by the Noachian deluge ? In examining both of these points the Italian philosophers were by far the most conspicuous, and it is difficult to understand how the sound conclusion of Fracas- torio (1517), Scilla (1670),* Eamazzini,t and Vallisneri,J could fail to become the universal creed of geology. Palissy, the philosophic potter of France, published, in 1557, from his own experience, that fossil shells and other "figured stones" were the genuine exuviae of ancient marine animals. Yet, through all Europe, the majority of naturalists, " vulgi persuasione occupati,"|| believed these admirable and venerable records to be mere lusus nature, unworthy of serious investigation, as a basis of true and sound geology. The 17th cen- tury closed before the expiration of this absurd controversy ; but as truth infallibly gains strength by even the most unworthy contests, the strong interest attached to the solution of this problem spread universally among naturalists the conviction that great discoveries concerning the structure of the earth were to be accomplished,' and the mode of contemplating its connection with zoology received very capital improvements. Progress of Palaeontology in England. In England, especially, the superior interest which belonged to the thousands of fossil plants and animals, was fully understood by Plot, Llwyd, Kay, Lister, Woodward, and Moreton ; who by their rich collections, and splendid publications, and resolute though unsuccessful efforts to deduce the causes which had thus buried and preserved imperishable in their everlasting tombs the organic remains of a former world, undoubtedly kindled that ardent spirit of inquiry respecting the structure of the earth, for which the English philosophers of the 17th century were honourably distinguished. Nevertheless, the progress of geology in England was still retarded by the fettered condition of other sciences, and by a peculiarly un- happy conjunction of truth and fiction. The correct view of the original nature of "formed stones, or petrifactions," was coupled by Woodward and his numerous followers with the assertion, that all the strata superimposed on one another in the crust of the earth, with all their included myriads of fossil animals and plants, were deposited by one general flood, " the deluge !" Italy, again, vindicates her claim to be forward in teaching phy- * La vana speculazione disingannata, Napoli, 1670. t De font. Mutin. Scat., b. 1633, d. 1714. His observations are quoted by Vallisneri, Lazzaro Moro, Linnaeus, &c. J De corp. mar., and other works, b. 1661, d. 1730. Palissy's work was first printed at Lyons in 1557. The edition of 1580, usually referred to, was the third. || Baier. Oryclographia Norica. 12 PBOGrBESS OF THE SCIENCE. sical truth. Ramazzini, 16th century, thus corrects the prevalent error : Strata terrae varia, aquali ordine et distantia constanter ob- servantur, ideoque et haec soli accretio, tarn bene distincta, multorum seculorum potius, quam communis cataclysm! tumultuarium et tur- bulentum opus censeri debeat. The great Swede who quotes this passage, (Linnaeus, Syst. Nat., 1770,) gives an excellent sentence of the same kind : Cataclysrni universalis certa rudera ego noridum attigi ; quousque penetravi ; minus etiam veram terram adamiticam, sed ubique vidi factas ex sequore terras, et in his mera rudera sensim praeterlapsi aevi. Regn. lapid. By way of contrast take the follow- ing from Baier, (1708) : Quse quidem opinio tarn firmiter insita est animo meo, ut quotquot intueor testacea e marinis fossilia, totidem catholici illius cataclysmi monumenta videre me arbitrer, aureis velut inscripta litteris : MEMOE. TJNIVEESAL. DILTIYII. Even in 1740, we find the great Italian author Lazzaro Moro* the worthy precursor of Hutton, Playfair, Brocchi, and Lyell gathering all his strength against the Woodwardian hypothesis of the diluvial origin of the strata, and their regularly arranged and successively deposited fossils. This fatal error, the stumbling-block of the " theorists" of the 18th century, lay at the root of the brilliant hypotheses of Burnet, Wood- ward, and Whiston ; and now, though discarded by every sound geologist, it remains a serious impediment to the diffusion of correct general principles. One great merit, however, strikingly characterizes the early English school of geology, even in its greatest aberrations, a thorough conviction that the organic remains entombed in the earth were the surest evidence of the revolutions which it had undergone. Lister. In consequence, the whole island was filled with collections of fossils, which were compared with native and exotic living species, and almost every naturalist of note from the time of Lister contri- buted something to the stock of information respecting them. That distinguished man, equally industrious and fortunate, and in general free from theoretical prejudice, had the glory of perceiving and of recording in a single instance the principle of mutual dependence between the strata and their organic remains, which afterwards, generalized and promulgated by Smith, became the most important instrument of investigation which has ever been presented to geology. Speaking of a small species of belemnite, (B. Listen), which is figured in his Historia Animalium An g lice, he says it is found in all the cliffs as you ascend the wolds, for above a hundred miles in com- pass, at Speeton, Londesbro' and Caistor, but always in a red, ferru- ginous earth. This correct and remarkable result is a striking example of the possibility of even holding in the hands a brilliant discovery, without knowing its value, or taking any steps to ascer- tain its importance. * De Crostacei et degli altri marini Corpi che si truovano su' monti. Vonezia. 1740. LISTEE SMITH CFYIEB. 13 A century later, the perception of the same truth, in several in- stances near Bath, and the demonstration of its applicability to the whole secondary series of the strata of England, enabled Mr. Smith, by his own unaided efforts, to establish the geology of England on a basis from which it can never be shaken ; an accurate classification of the stratified rocks, in the order of their relative antiquity, accom- panied by catalogues of their organic contents, and a map of their ranges on the surface of the island in conformity with the section of the interior. To study the monuments of nature according to the principles developed by Mr. Smith ; to ascertain by the order of succession and by the organic remains what were the contemporaneous effects of the natural agents employed in the formation of the earth in all parts of the world ; is the great problem of modern geology. By the aid of zoological and botanical researches we determine the relative antiquity of every species of fossil plant and animal, and assign the relative period during which its existence was continued. Orthoceratites productae, trilobites, and many crinoidea, belong to the older and lower rocks ; certain species of echini and shells mark the oolitic strata ; while others belong to chalk ; and a series of plants, corals, shells, and vertebral remains, lies above the cha^k, but is not found below. Such inferences, drawn from observations in Europe, have been found constant even in the new world ; and the powerful in- strument of research thus placed in the hands of the observer, having been wielded with the caution requisite in questions of analogy, the time is arrived when the principles disclosed by Mr. Smith's researches near Bath, and illustrated by Cuvier's philosophical description of the environs of Paris, will be found universally applicable ; for already the distant slopes of the Himalayan and the Andes, and the shores of Australia and Greenland, are united in the mind of the geologist who contemplates their coeval stratification. Hypotheses. We shall here close our short account of the growth of geology into a science, without being tempted to indulge in the vain amusement of ridiculing those crude and visionary schemes which have too long been known by the misapplied title of theories of the earth. While the paths of observation, along which alone the foun- dations of the science are to be sought, were hard and difficult, those of hypotheses were easy, flowery, and inviting. The globular figure of our planet, the inequality of its surface, and the occurrence of marine shells in mountains far from the sea, have been thought suffi- cient data for rashness and speculation to construct detailed theories of the earth, to determine the constitution of its centre, and to de- scribe, as if they had actually beheld them, the successive revolutions which it had undergone. These unfortunate hypotheses were most numerous and discordant 14 MATERIALS IN THE EARTH. during the period when positive geology had made the least progress ; with the advancement of knowledge they diminished in number and improved in consistency, and at the present moment, though every professed theory has lost its power of fettering the mind, there is a tacit but almost universal agreement in those fundamental principles of structure, and circumstances of origin, by which not only every passing theory must be judged, but to which also all good observa- tions and sound inductions must be referred. To develop these principles in a settled order, to illustrate by their aid the geological structure of the British isles, and to connect the geology of Britain with that of Europe and the terraqueous globe at large, and thus to rise by a legitimate process to the most comprehensive inferences which the subject admits of, is the aim of the following pages. We shall not, at the outset of our inquiry, prejudge the important questions which will arise for discussion, by deciding between Hut- tonian and Wernerian, or any other hypotheses ; but allowing to their ingenious authors the merit of having really promoted geology by stimulating curiosity and by directing inquiry, we shall for the pre- sent neglect them altogether, except so far as they may assist us to read well and interpret aright the rich and impartial volume of nature. CHAPTEE II. ELEMENTARY VIEWS OF THE STRUCTURE AND COMPOSITION OF THE CRUST OF THE EARTH. Materials in the Earth. mean Density of the Earth. The first question which presents itself to the inquirer into the natural history of the earth is, what are the materials employed in its construction ? To answer this question fully, and in all its extent, is now, and will, probably, for ever remain impos- sible, because with respect to the interior of the globe we can learn nothing from direct observation, nor infer from astronomical researches anything more than that the materials, whatever they are which compose the central parts, must have there a specific gravity, very much greater than that of the rocks which appear near the surface. The mean density of the prevalent rocks hitherto discovered is about twice and a-half that of water ; but the mean density of the whole terraqueous mass is at least five times that of water. We may, there- fore, safely conclude that the central portions are much heavier than the external crust ; but beyond this, and the information yielded by deep-seated volcanic action, all is speculation. GEOLOGY DISTINCT FROM. COSMOGONY. 15 Specific Gravity of the Materials. It must not be concluded that because in the central parts the materials, whatever they are, have there a specific gravity greater than those near the surface, they would also remain heavier if brought to the surface, for the com- pressibility of matter under pressure would necessarily tend to the condensation of the internal nucleus of the earth, and that in so high a degree, if the internal substances be of the same compressibility as those in the crust of the earth, as to make the mean density of our planet very much higher than it is known to be. Putting out of view the question of the chemical relations of the internal substances of the globe, and confining ourselves to mechanical considerations alone, we should have, as conclusions of the greatest probability which the subject admits of: First, that the superior density of the internal parts of the globe is occasioned by the accumulated pressure which they have to sustain. Secondly, that the effects of this pressure in condensing the in- ternal parts of the globe would be far more considerable than they are, were they not resisted within by some general antagonist force ; such as the expansive power of heat, or an extraordinary want of compressibility among the particular substances operated on. Thirdly, that the earth's spheroidal figure has been attained in consequence of its having formerly been entirely fluid, during rota- tion on its axis, and is preserved because the internal arrangement of its materials, whether solid or fluid, is in equilibrio with the velocity of its rotatory movement. ^imitation of inquiry It cannot be too often or too early im- pressed upon the mind of the student that geology has no dependence on systems of cosmogony. The history of its successive systems of life can be investigated without entering on the question, whether the other planets are in- habited ; the revolutions which it has undergone, since it became a globe, may be subjects of successful inquiry, though we disclaim all attempt to determine from what real or fancied nebula it was con- densed, or by what creative process it acquired revolution round the sun, rotation on an axis, measured proportion of water, and limited tract of surrounding atmosphere. These, and many other great and noble problems, are interesting to geology ; the partial solution of them brings some useful help even to the interpretation of the earth's history ; geology sympathizes with and benefits by all the knowledge of nature ; but it has enough to do in its own peculiar field of research. It is wholly a science founded on observation and inferences, and limited to the phenomena presented within a small depth from the surface of the earth. The regular disposition of the materials of our planet does indeed permit us, in many cases, to infer, with the highest 16 MATERIALS IN THE EARTH. probability, what is the condition of its interior to a depth far be- yond that actually visible to human eye ; but still all the aids of inductive science are ineffectual to penetrate more than a few miles below the soil. It may, indeed, be the case, since the level from which volcanoes arise is uncertain, that the materials which they vomit have been derived from greater depths, but the improbability that these materials, after undergoing fusion, should be restored to their original condition, must make us hesitate to adopt volcanic products as evidence of the exact nature and condition of the sub- stances in the interior of the earth. Our observations are, therefore, nearly confined to what is technically called the crust of the earth, and our direct inferences descend no lower than the rocks which appear in this crust. Earthy Compounds. There is hardly any tract of country so limited as not to show a considerable diversity of earthy aggregates. Even in those districts which possess neither quarries, nor mines, nor cliffs, nor natural valleys, the surface of the land and the shores of the sea are generally strewed with fragments of different stones transported by some ancient powerful currents from regions in which nature is more prolific, or more clearly reveals her treasures. In the more level countries the principal varieties of the earthy compounds or aggregates are included in the terms limestone, sand- stone, and clay, of different colours, hardness, and fineness of grain. Each of these great divisions of rocks contains essentially a peculiar species of earth which imparts to the mass a particular derivative character. Thus Lime is the base of limestone. Silica of sandstone. Alumina of clays. Magnesia is an essential ingredient in certain limestones. Carbon is the characteristic element of coal. Soda is the basis of common salt. If we now turn our attention to the mountainous tracts, where crystallized minerals present themselves in an endless variety of com- bination, we shall, perhaps, be led to expect a corresponding abun- dance of primitive substances. But chemistry has taught us that all this seeming inexhaustible variety is occasioned by a few earths, metals, and combustibles, and some of these are so rare, and even solitary in their occurrence, as to be of little importance in this in- quiry. By far the greater number of earthy minerals are composed of the four substances, silica, alumina, lime, magnesia, variously combined with alkalies and acids, and differently coloured by metallic oxides, &c. A good general knowledge of siliceous, aluminous, calcareous, and magnesian minerals and rocks, is therefore the portion of miner- alogy most essential to a geologist. COMPOSITION OF GEANITE. 17 By way of marking the distinctions of geology, mineralogy, and chemistry, we may take three successive aspects of one rock, granite. The geologist considers the circumstances under which this rock is found whether in great mass or small veins ; in the axes of moun- tains, or in comparatively plain countries ; the peculiarities of its structure on a great scale ; the constituent minerals ; the associated strata ; the period of its fusion and eruption. He observes that it is composed of three minerals principally, so that it may be thus repre- sented : (Quartz, Granite composed of < Felspar, (Mica, &c. To the mineralogist granite is an object of study, because it is composed of certain minerals, whose constant characters it is a part of his science to determine. It is not granite which he studies, but the mineral constituents of it. These he examines separately by their geometrical forms their specific gravity, hardness, effects on light, electricity, magnetism, &c. The quartz is gray, or purely translucent, of crystalline external form, or adapted in form to the other minerals. The felspar is red, gray, green, white, &c., always of crystalline structure internally, often distinctly terminated by primary or secondary planes sometimes in detached large crystals. The mica is in brilliant plates ; when perfectly crystallized, they are six-sided ; the colours black, gray, white, &c. Finally, the chemist takes these separate minerals and analyzes them, resolves them into their several ingredients or chemical ele- ments examines the properties and proportions of these, and in- vestigates the laws of their combination. The result of the whole process may be thus represented : Qua rt , {^r-::-:;::::::::::::::::::::::::::::::::::::^ {gSS:::::::::::rSi (Potassium 81*5 Felspar. Mica. Potash A1 . /Aluminium 53-2 Alumma \0xygen 46-8 (Oxygen 18-5 /Aluminium 53-2 (Oxygen 46-8 (Silicium... 48-4 SUica .......................... lOxygen ................. 51-6 p . , /Potassium... ......... 81-5 Potash ......................... \0xygen ................ 18-5 /Magnesium ............ 61'4 ................. \Oxygen ............... 38-6 T . /Calcium ................ 71-3 Lime ........................... \0xygen ................ 28>7 18 MATERIALS IN THE EAETH. By such researches carefully conducted it appears that one-half of the ponderable matter near the earth's surface is composed of an ele- ment which, released from combination, expands 2000 times at or- dinary temperatures, and becomes oxygen gas, a constituent of our atmosphere. Elementary Substances. All the various aerial, liquid, and solid compounds which belong to this globe are reducible to about sixty- three ingredients, which are termed simple or primitive, because, in the present state of chemical science, they appear incapable of further decomposition. Of these Fifty-one are metallic bodies, brilliant, electropositive, and, with the exception of potassium and sodium, heavier than water. Ranged in the order of their affinity for oxygen we have the metals in the following three groups : First Group, Six absorb oxygen at all temperatures, and decompose water at all tem- peratures. Of these three are bases of the alkalies, those marked * being most abundant. Potassium,* sodium,* lithium. Three are bases of alkaline earths, that marked * being most abundant. Barium, strontium, calcium.* Second Group Thirty-six? absorb oxygen at high temperatures. Never decom- pose water at temperatures below 122 F. Of these the following seven are bases of earths, those marked * being most abun- dant. Magnesium,* aluminium,* thorium, glucinium, zirconium, yttrium (silicium*. This not always ranked as a metal). Another group consists of Manganese, zinc, iron, tin, cadmium, cobalt, nickel. Another of Arsenic, chromium, vanadium, molybdenum, tungsten, columbium, antimony, ura- nium, cerium, bismuth, titanium, tellurium, copper, lead. Of the following eight metals as yet little is determined: Erbium, terbium, didy- mium, lanthanium, niobium, norium, ilmenium, pelopium. Third Group. Nine part with oxygen at high temperatures: Mercury, silver, gold, platinum, palladium, rhodium, osmium, iridium, ruthenium. Eight non-metallic combustibles, Sulphur, Iodine, Carbon, Phosphorus, Bromine, Fluorine? Selenium, Boron. Four gases, Hydrogen, Oxygen, Azote, Chlorine. Every substance in this list is found in the mineral kingdom ; and while the chemist examines them separately in his closet, the min- eralogist studies their combinations in the field. minerals. It may, perhaps, be imagined that innumerable com- binations are derived from these sixty -three primary ingredients. But as many of them are excessively rare, as the remainder combine only SPECIES OF MINEKALS. 19 upon certain principles, the number of mineral species really deter- mined is, in fact, not large, perhaps hardly exceeding 500. Nor is the geologist always called upon to make himself acquainted with all even of this moderate number. Unless his labours are devoted to the detailed phenomena of volcanic productions, or of mineral veins, he will seldom have occasion to observe more than one-tenth of the number. The reason of this is that a large portion consists of rare and local species, and that, in combining to form rocks, the others are associated in families, and united into specific compounds without much permutation. Thus, quartz, felspar, hornblende, chlorite, and mica, frequently occur together in granitic rocks, but other minerals, as calcareous spar, &c., scarcely ever accompany them. In conse- quence, then, of the rarity of many minerals, and the uniformity of the assemblage of others, there is really much less difficulty than might be expected in recognizing and discriminating the rocks. To class and to describe them in a true natural order is difficult, to com- pare and to know them according to their mode of occurrence is easy. Supposing, then, that the student has already made himself ac- quainted, by examination of a few specimens properly labelled, with the more common and remarkable rocks, as limestone, sandstone, and clay, various kinds of slates, basaltic, porphyritic, and granite rocks, we shall now proceed to inquire in what manner they are arranged in the earth. Stratification. The best way of prosecuting this inquiry, is to begin at home, where precise information can be most easily acquired ; next to com- pare our own with neighbouring districts ; and, finally, extending our views over the whole surface of the globe, to class the pheno- mena, and deduce the general results. Arrangement of Rocks on the Surface. It might be very excusable before countries were cleared and cultivated, and before their various mineral productions were employed and understood, to imagine that the materials of the earth were heaped together in confusion, the result of a chaotic formation ; but at present, such a notion will not stand the test of a moment's reflection. One district has chalk be- neath the surface, another limestone, a third coal, and a fourth granite, and these are never mixed or confounded together ; so that the most careless observer must conclude that the different rocks are arranged after some ascertainable method. These different rocks are not mere insulated patches irregularly scattered through the country, but gen- erally connected on the surface in long ranges, which in all the eastern half of England have their prevailing direction from north- east to south-west. Thus the chalk of the Yorkshire wolds is 20 STEATIFICATION. prolonged (see the Map of the British Isles) through Lincolnshire, Norfolk, Suffolk, Bedfordshire, Wiltshire, Dorsetshire, &c. ; the oolitic limestones range through Lincolnshire, Northamptonshire, Gloucestershire, and Somersetshire ; and many other limestones and sandstones hold a parallel direction. Hence it happens, in proceed- ing from London toward the south-west, west, or north-west of England, that we cross so great a variety of rocks, and so many ranges of hills. A person proceeds from London to North Wales. After passing low, gravelly plains in the drainage of the Thames, he climbs, by a long slope, the chalk -hills of Oxfordshire ; crosses vales of clay and sandstone ; ascends a range of oolitic limestone ; traverses wide plains of blue and red marl ; arrives in districts where coal, iron, and lime- stone abound ; and, finally, sees Snowdon composed in great measure of slate. And if, in proceeding from London to the Cumberland Lakes, he finds the same succession of gravelly plains, chalk hills, clay vales, oolitic limestone ranges, blue arid red clays, coal, iron, and limestone tracts, succeeded by the slate rocks, which compose the well-known summit of Skiddaw, will he not conclude that something beyond mere chance has brought together these rocks in such ad- mirable harmony ? Will he not have reason to conjecture that in the interior of the earth regularity of structure must prevail ? internal Arrangement of Rocks. This conjecture becomes cer- tainty when we explore the relative position of rocks as it is dis- played in wells, pits, quarries, and mines, the works of human industry, or laid bare in cliffs and ravines by the hand of nature. Here we see the rocks formed in layers or tabular masses of various thickness, but always of very great superficial breadth or extent, and placed upon one another like the leaves of a book. These layers are called strata. Along the edges of hills, in the course of precipitous valleys, and by the margin of the sea, it not only is not difficult to recognize this truth, but it is almost impossible to avoid perceiving it. Many parts of the English coast present what is termed a natural section of the rocks, and accordingly, whoever visits the shores of Northumberland, Yorkshire, Kent, Hampshire, Cornwall, South Wales, or Cumberland, may easily satisfy himself of the stratification of most of the limestones, sandstones, clays, and slates of England. For most of the cliffs are composed of several distinct layers of rock, which are piled one upon another in a regular order, preserve a defi- nite thickness, and appear under the same circumstances in many distant places. In the interior of the country the same conclusion is to be drawn from examining precipitous hills and deep valleys ; and even in the flattest country, art supplies the means of investiga- tion which nature has denied. The wells, and pits, and mines, which have been found necessary for the comfort of civilized man, all dis- SUPERPOSITION INCLINATION. 21 play the same general truth, and lead us to conclude that the prin- ciple of stratification among rocks is confined to no particular country, but whether in the New or the Old World, in continents or in islands, it is so remarkable and so constant, that colliers sink deep pits, and miners undertake extensive levels, in full confidence that no exception to its generality will affect the result of their enterprises. It is not a speculative truth, but a practical law of nature, and is probably the fact of most extensive influence in the whole theory of geology. So many important facts respecting stratified rocks flow in toge- ther upon the observing mind, that it is not easy to analyze them in the exact order of their occurrence. A person attentive to the subject cannot fail to discover, even in a very limited district, that the different strata which appear above one another, like the leaves of a book, are also, like them, arranged in a certain constant order of succession. A stratum which in any one situation is found be- neath another will never, in any other situation, be found above it. Superposition of Strata. As a bookbinder sometimes neglects to bind in a particular leaf, so nature sometimes omits a particular rock ; but she never misplaces the rocks, as the careless workman sometimes misplaces his pages. Let us take, as an example, the cliffs on the coast of Yorkshire, between Flamborough Head and Robin Hood's Bay. Gristhorp Cliffs are crowned by calcareous sand- stone rocks, which rest on a thick, bluish, argillaceous bed ; under this is a brown, ferruginous sandstone, and, still lower, a thin, cal- careous layer full of fossil shells. In Scarborough Castle Hill, the same calcareous sandstone, argillaceous bed, brown ferruginous rock, and fossil bed, occur in the very same order of succession. Or let us station ourselves at Leeds, and examine the coal-pits of the neigh- bourhood, notice how many seams of coal are cut through, and what beds of sandstone and shale, and what layers of ironstone are met with. Then, inquiring of the workmen, we shall learn that the same "set of beds" is wrought at another pit. At this other pit we shall find the same beds of coal in the same order of succession, at nearly the same distances from one another, and of nearly the same qualities and thicknesses ; and this strict analogy will be found at several pits over a considerable extent of ground, and, therefore, here, as well as on the coast, we obtain proof that in a limited district the strata are arranged with respect to one another in a certain constant order of succession. inclination of Strata. Pursuing our investigation, we find that the strata are generally so disposed that their planes or broad sur- faces are not exactly level or parallel to the earth's spherical surface, but sloping in some one direction, so as, in that direction, to sink deeper and still deeper into the earth, and to be covered by other 22 STRATIFICATION. strata. This slope, this deviation from the horizontal position, is called the dip or inclination of the strata ; and the rocks are accor- dingly said to dip or incline to this or that part of the horizon. The different rocks which compose the interior to a considerable depth are, therefore, in consequence of this inclination, exhibited in succes- sion on the surface, and hence it is that mankind is furnished with a vast variety of mineral productions suitable to its numerous neces- sities. Continuity of strata. Any one thus far initiated in geology, and possessed of common powers of observation, will be able to compose a list or scale of the strata which occur in his own neighbourhood, naming them in the exact order of their succession or superposition, and thus will be furnished with the means of comparing his own district with others near and distant. The results of this compari- son are very important, for we thus learn that one general order of succession is observed among all the stratified rocks of England. Certain strata are locally deficient, but all those which do occur together are found invariably in the same relative position. The series of stratified rocks in the north of England, taken in a general way, is expressed by the following names : chalk, gault, Kimmeridge clay, coralline oolite and calcareous grit, Oxford clay and Hackness rock, cornbrash and Bath oolite rocks, lias shales, red marl and sand- stone, magnesian limestone, coal system, mountain limestone, slate. The series in the southern parts of England is precisely accordant, except that the magnesian limestone is there nearly deficient, and that the Kimmeridge clay is covered by some strata which do not pass the river Humber. Besides, we find the strata of the north of England actually connected by mutual extension with those of the same names in the south of England, so that we thus prove their continuity over large tracts, as well as the constancy of the order of their succession. By means of these comparative observations, begun by Mr. Smith in 1790, and continued with unabated zeal by his numerous disciples, the whole series of English stratified rocks has been ascertained, and arranged in tabular order ; and the geologists of England have, in consequence, furnished to the rest of the world a standard of com- parison, by which to determine how far the laws of stratification disclosed in this island are applicable to other countries. The following table, taken almost verbatim from Dr. Fitton's valuable notes on the History of English Geology, (Phil. Mag. 1832,) presents the list of English strata as published by Mr. Smith in 1815, and the corresponding arrangement admitted among geologists; and thus at one view may be seen the entire distinctness of Mr. Smith's whole system of classification and method of naming, from that of any earlier continental writer, and the almost perfect exact- SEEIES. 23 ness with which his views and names have been adopted by the modern school of English and European geology. stratification a General Principle. Considerable labours remain to be accomplished before even the stratified rocks of Europe can be 24 STBATIFIED AND TTNSTBATIFIED BOCKS. completely compared with those of England, and the want of evi- dence is still more severely felt with respect to the three other quarters of the globe. Nevertheless, the following important general results may be regarded as certain. The principle of stratification is found to be universal ; that is to say, in every country of sufficient- extent, various rocks are found to be superimposed on one another in a certain settled order of succession, and these rocks are not found only in insulated patches, but often hold their course across provinces and kingdoms. Throughout the whole area of Europe, from the Oural mountains to the Atlantic, and from Lapland to the Mediterranean, the strati- fied masses of the earth, taken in their generalities, are arranged upon the same principles, follow one another in the same exact order of succession, and, in fact, form parts of one vast system of rocks, once more perfectly connected than at present. What is known of the geology of North Africa, Egypt, Syria, the countries bordering on the Caspian, Siberia, and Hindustan, leads to a confident belief that the same general system, modified by local circumstances, will be found applicable to the greater portion of the surface of the Old Continent. Analogy of Distant Deposits. Important agreements between the strata of North America and New Holland and those of Europe, have been already determined, and the time will probably at last arrive, when, though it cannot be proved, as Werner perhaps ima- gined, that similar rocks were at the same time deposited in every part of the bed of the ancient sea, at least it will be possible to show that the same system of natural processes was everywhere in progress, contemporaneously or successively producing analogous effects ; and to ascertain the relative antiquity and accompanying circumstances of even the most distant deposits ; and thus to exhibit, in chronolo- gical order, a history of all the varied yet harmonious operations, by which, in regular gradation, this globe was filled with long-enduring monuments of the everlasting power and wisdom of its Creator, and made fit to be inhabited by a being capable of interpreting the con- ditional effects, recognizing the appointed agency, and venerating the universal cause. Distinction of Stratified and Unstratified Rocks. Relative Situation. Stratification is, therefore, the most general condition, or mode of arrangement of the rocks which appear in the crust of the earth ; and in the wide plains and gently undulated portions of the surface, it is often the only one discoverable. A per- son of good discernment, who should pass his whole life in investi- gating the south-eastern part of England, or the northern part of DISTINCTIVE CHAEACTEES. 25 France, might conclude, from every observation he could there make, that the external materials of the earth were universally stratified. On the other hand, the inhabitant of the mountains sees so many examples of granitic rocks, totally devoid of any appearance of strati- fication, and sometimes finds that structure in the slate rocks so dubious and inconclusive, that he is wholly unable to comprehend the magnificent chain of inductions derived from the study of strati- fied rocks. Unstratified rocks generally abound along mountain chains and groups, and very often form their axis or nucleus. Strati- fied rocks fill the plains, and form the encircling flanks of the moun- tains. When a vast mass of unstratified rock, as granite, forms the nucleus of a mountain group, the stratified materials which surround it generally slope away on all sides, as if the granite had been pro- truded from below these strata, and, during the act of its uplifting, had broken them, and caused them to assume their several inclina- tions. Other unstratified rocks, as basalt and porphyry, appear amongst the stratified rocks, sometimes in irregularly lenticular masses, as if they had been spread in a melted state around a com- mon centre, sometimes filling long vertical fissures in the strata, as if they had been injected from below. Mineral Characters' On comparing together the stratified and unstratified rocks, we find their mineralogical composition extremely different. The stratified rocks are earthy aggregates, as sandstones, clays, or simple chemical precipitates, as limestone ; such materials, in fact, as we know to be accumulated in the same mode of arrange- ment by modern waters. The unstratified rocks, on the other hand, are generally and evi- dently crystallized masses, often analogous to volcanic products, or compounds containing essentiaUy minerals which are not known to be producible from water, but in several instances are obtainable by artificial heat, or generated in the deep furnaces of which volcanic mountains are the vents. Stratified rocks have evidently been deposited successively from above ; the lowest first, the uppermost last, in obedience to the laws of gravity. Unstratified rocks, on the other hand, seem to be derived from the depths of the earth, and to have been ejected or uplifted from below the strata, as volcanic matter is protruded at the present day. Contents. Stratified rocks contain very generally the remains of the plants and animals which were in existence at the period of their formation, exactly as remains of the present races of plants and animals are found buried in the modern deposits of water. But unstratified rocks contain no such evidences of watery origin or mechanical aggregation. Origin. By all these characters, separately and comparatively 26 STRATIFICATION. considered, the two great divisions of materials which compose the external parts of our globe are proved to have been produced by entirely opposite causes. Stratified rocks are analogous to the mo- dern products of water, and are therefore called Neptunian, while unstratified rocks are analogous to the modern products of subter- raneous fire, and receive the names of Plutonic and Volcanic, accord- ing to the degree and circumstances of this analogy. There are some cases of the production of strata enveloping shells and plants, &c., by the action of wind Eolian strata, as Nelson calls them in his account of Bermuda.* Mode of study. The distinction now insisted upon between the Neptunian and Plutonic formations, between rocks of deposition and rocks of eruption, is of the highest importance, and deserves the first notice, even on the very opening of the subject of geology. For not only are these different classes of rocks distinguished by most impor- tant general characters, but even the methods by which they are to be investigated, and the preliminary knowledge required for this pur- pose, are entirely distinct. Amongst the stratified rocks a knowledge of zoology and botany is required to develop the past history of innumerable remains of plants and animals, which were buried at successive periods ; on the contrary, among the mountains associated with granite, where minerals of every hue and form appear in every different combination, scientific mineralogy is of much higher im- portance. In consequence, geology divides itself into two branches, one of which links itself with the natural history of modern plants and animals, and the other with chemistry and mathematics. And we have now, and have always had, two distinct groups of geologists, whose progress and discoveries have been as different as the pre- liminary knowledge which their different spheres of research required. A geologist of adequate attainments must indeed be supposed ac- quainted, at least generally, with both branches of this magnificent subject ; and therefore a person entirely ignorant either of mineralogy, on the one hand, or of zoology and botany on the other, must be considered as only half-educated. He may, indeed, be a very useful local observer, but he must be further instructed in his science before he can be sent to explore an unknown region, or permitted to give an opinion on the whole theory of geology. As much knowledge, therefore, as can be easily gained of the minerals which enter most frequently into the composition of rocks and veins, and of the natural history of the plants and animals whose remains lie buried in the strata, is absolutely necessary to every pro- fessed geologist. Yet on this account the student ought by no means to be discouraged ; for this preliminary knowledge will be quickly, * Nelson in Proc. of Geol. Society. STRATA DEPUTED. 27 though insensibly, acquired by an intelligent observer, in exact pro- portion to his need of it. In a level country composed of limestone, sandstone, and clay, the multitudes of organic remains which con- tinually meet his eye will infallibly procure him the power of dis- criminating their specific forms ; and among the mountains associated with crystalline granite, the endless repetition of the objects will generate a mineralogical tact in the eye, and a mechanical, if not mathematical, notion of the structure of crystals. The summary observations which will be introduced in this treatise on the preliminary sciences of zoology, botany, and mineralogy, will be placed with those divisions of the subject to which they respec- tively belong, and where they will be the most intelligible as well as the most useful. On Stratification in general. Strata, the term Denned. Strata, layers, and beds are synonymous terms. "Strata," says Professor Playfair, "can only be formed by seams which are parallel throughout the entire mass." This defini- tion, founded upon the supposition that loose materials deposited under water must be arranged in layers parallel to the surface of the water, undoubtedly contains the general or fundamental idea of strati- fication, but is often too abstract for practice. It includes too much, for slaty cleavage produces laminae more truly parallel than Nep- tunian strata ; and it excludes many layers produced under greatly agitated water, on lines of sea-coast, and in the direction of sea- currents. The most remarkably regular and parallel seams or divi- sions between strata happen in calcareous and argillaceous rocks ; but the partings in sandstone are much less uniform. A particular shelly bed of stone lies at the top of the coralline oolite of Yorkshire, and may be traced for a great distance ; a red band, long since noticed by Lister, lies at the base of the chalk of Yorkshire and Lincolnshire for sixty miles in compass ; the cornbrash limestone, seldom more than ten feet in thickness, is continuous from Dorsetshire nearly to the Humber. In these instances, therefore, Playfair's definition ap- plies very well. On the contrary, the beds of sandstone with coal which are interposed in the oolite system of Yorkshire, are altogether 00 feet thick near Robin Hood's Bay, but dwindle toward the south, and are entirely deficient before reaching the Derwent. Such beds are therefore wedge-shaped ; and cases _____ - _ - sometimes occur where, by attenuation in all direc- *"" ' tions from the centre, they become lenticular. See fig. 4 for these and other appearances. interposed Strata. The strata, therefore are not all co-extensive. Limestones and thick clays are probably the most persistent and 28 STEATIFICATION. regular, sandstones the most limited and local. Local or interposed beds cause the principal differences between distant portions of the same formation. The lias of England rest immediately upon red and bluish marly clays with white gypsum ; at Luxemburg they are separated by a thick Sandstone. In the north Lenticvlarinttrpoiedanddwtdtdbed,. of England, magnesian limestone separates the coal from the upper red sandstone ; but in other parts of the island these two formations are in contact. In the breast of Ingleborough, the limestone beds are aggregated into one vast mural 4 precipice or scar ; but as we proceed northwards this mass opens to admit layers of sandstone, shale, and coal, which gradually increase under Crossfell, and swell out to a vast thickness in Northumberland, so as to contain several valuable seams of coal, thick rocks of sand- stone, and abundance of shale, between the horizontally separated beds of limestone. The oolitic strata near Bath are composed of two portions the upper or great oolite, and the lower oolite and between them is a series of calcareous and argillaceous beds called fullers' earth beds, sometimes 150 feet thick. As we proceed northward into Lincoln- shire, the fullers' earth beds are excluded from the series ; still farther north the whole series is changed ; so that in Yorkshire it includes thick layers of sandstone, shale, and coal. On a first view the dis- tricts of Bath and Yorkshire are very unlike, but the contemporanity of their deposition is certain from the continuation of the same oolitic beds through both of them. Thickness. The thickness of the beds or strata varies exceedingly, and seems to have reference to the rapidity, regularity, and continuity of the deposition, and the rate of drying or consolidation of the materials. The chalk rock is about 500 feet thick, and in all this great mass we can scarcely trace any decided beds ; though the layers of flint at equal distances (four to eight feet,) and the difference of the organic remains at different depths, evidently prove a succession of stratified deposits. The great oolite near Bath is, on the contrary, divided into a certain number of beds, definite in quality, thickness, and order of position. j.amiiijr. A certain stratified rock, therefore, is composed of one or more layers of strata, but this is by no means the last term of the analysis. Each bed is often composed of many laminae, which are sometimes parallel to the plane of the bed itself, and sometimes lie OBLIQUE LAMINATION. 29 Parallel and oblique Jamination. in it at different angles. Thus micaceous laminated sandstones, and in particular the best flagstones of the coal districts, are composed of a multitude of thin layers parallel to the plane of the bed, and en- tirely covered by plates of mica, which probably cause the splitting of the stone. This appearance is very analogous to the laminated sand quietly left by the successive floods of a river. But the coarser flagstones of the same coal districts are often com- posed of laminae, laid at various angles to the plane of the bed, and in consequence producing a rough, uneven, shattery surface, and a ten- dency to oblique fractures ; thus, in fig. 5, a represents the regu- lar, and b the coarse, irregular flag- stones. 5 Such appearances of oblique lamination are occasionally found in the modern sediment of agitated waters, both in the banks of rivers and on the sea-shore. When these oblique laminae extend through thick beds, they some- times cause a slight difficulty in determining the dip of the strata, and are then called false bedding. Some of the coarse upper beds of the great oolite of Bath, Gloucestershire, Northamptonshire, and Lincolnshire, as well as of Normandy, are remarkable for this false bedding. But it is in the coarse sandstones that we see the most remarkable examples of this structure, as on the coast at Scarborough, and under Nottingham castle. The more violent the action of the water, the less regular is the internal constitution of the layers found beneath it. Let any one with this view compare the effects of the tide beating upon the sand and pebbles of the eastern coast, or the tumultuous products of a mountain river, with the tranquil deposit and sediment on the alluvial lands near Lynn and near Hull. In the former case the materials are frequently found heaped together in laminae, variously and con- fusedly inclined to one another ; in the latter they are all parallel to the horizon, and to the general plane of the surface. The former case is exactly analogous to the false bedding mentioned in a preced- ing section, so general in our sandstone conglomerates, and in shelly beds of oolite ; the latter is exactly like the regular lamination of clays and shales. Like effects flow from like causes, and thus we are enabled to frame very plausible conjectures concerning the condition of the waters under which the several strata were accu- mulated. General Terms. In the same way as a number of similar laminas are sometimes united into one bed of stone, so several similar beds of 30 SERIES OF STRATA TERTIARY OR CAINOZOIC. stone are sometimes associated into one rock, to which a specific name is applied, as the oolite, the lias limestone, &c. Sometimes several of these rocks are grouped under the title for- mation, as the Bath oolite for- ^ 0oUttformation mation. Thus the lias lime- stone beds, the lower lias clay, marlstone beds, and upper lias clay, as represented in fig. 6, are all included in the lias formation, which rests upon the red sandstone formation, and is covered by the Bath oolite for- mation. Htw tttd Sandstone formation. Series of British Strata. The 6 following table exhibits a complete view of the whole series of British strata, grouped, according to their relative antiquity, into three lead- ing divisions, the primary, or Hypozoic and Palaeozoic ; secondary, or Mesozoic ; and tertiary, or Cainozoic strata ; it being understood that such divisions are chiefly adopted for convenience, as expressing with considerable accuracy certain general analogies of origin, com- position, and organic contents, which prevail amongst the members of each division, but yet are not to be considered as exclusively belonging to them. Two of these divisions are again subdivided, upon exactly the same principles, into systems of strata, which are marked by certain re- current rocks, striking analogies of composition, organic reliquiaB of similar types, and positions derived from convulsions of the same epoch. The systems are again usefully divided into formations ; these into their several component rocks ; whose ultimate analysis gives the strata, beds, and laminae of composition. The superficial accumula- tions of gravel, sand, peat, &c., which are classed under the head of diluvial and alluvial deposits, are not included in this list of strata. For the sake of the student to whom the mode of considering the sequence of rocks may not be familiar, the strata are here placed in the same order as they would be found on proceeding from the sur- face downward ; but the numbers are placed in contrary order, to indicate succession of time, upward. This table should be compared with that of Smith, p. 23, and of Werner, p. 8. Tertiary or Cainozoic Series of Strata. Partly lacustrine, but principally marine, sandy, and argillaceous, and with some calcareous deposits, abounding in shells and other organic exuviae, closely analogous to existing species. SECONDARY OR MESOZOIC. 31 Formations. Subdivisions. T> , , . , /Mostly fresh water and estuary \ Historical. OStglacml t deposits / Prehistorical. GlaciaJ Mostly marine, deposits of clay, boulders, gravel, &c. Preglacial Fresh water estuary and littoral deposits. (Littoral, shelly, and coralline) Red crag, shelly. \ group / Coralline crag. f \ Hempstead series. . ,, . J Limestones, marls, sands, &c., f Bembridge series. me \ on the Isle of Wight [St. Helen's series. I J Head en series. C "^ Upper or Barton clay group. T , , ! Marine groups of clay, sand, v Middle or Bracklesham ^ \ &c i sands. J Lower or Bognor group. rlav (Group of clays, sands, lig-> Woolwich beds. \ uites / Thanet sands. Secondary or Mesozoic Series of Strata. Principally of marine origin, with rare and local estuary deposits ; consisting of repeated alternations of limestone, flint, sandstone, sand, clay, iron ore, coals, salt, &c. , with organic remains, generally very distinct from existing forms of animals and plants. Formations. Upper Mesozoic Strata. Subdivisions. ( ^ Upper chalk softer. Chalk ^Calcareous with flints > Middle chalk harder. ( ) Lower chalk marly. / Sands more or less coloured^ Upper green sands. Green sand < by silicate of iron, and > Gault clay. (^ clays ) Lower green sand. Lower Mesozoic Strata. fA fluviatfle and estnarv de- 6 * 1 . 4 ^ Middle oolite f i j Calcareous, with sands and Upper calcareous grit. Coralline oolite. ^ Lower calcareous grit, Oxford clay Hackness rock. Clay. Cornbrash. Hinton sands. Forest marble. Bradford clay. > Great oolite/ Lower oolite j clays I j Calcareous, with clays and 1 sands... ,. * Fullers' earth rock. Inferior oolite. Feruginous sand. f "I Upper lias shale. Ironstone and marlstone. Lias \ Limestone and clay or shale .. > Middle lias shale. I Lias limestone. [_ J Lower shales and bone be * This series is taken from the south of England. A different type appears in the north. 32 PALEOZOIC AND HTPOZOIC. Formations. Lower Mesozoic Strata. Poikilitic series. Variously coloured sands, &c clays, Subdivisions. Upper variegated marls, gypsum, salt. Keuper sandstone. > Lower variegated marls. Red and white sandstone. Red and white conglo- merate. Primary or Palaeozoic and Hypozoic Strata. The Palaeozoic rocks, containing organic remains, mostly of marine tribes, and gene- rally extinct ; the Hypozoic rocks deficient of fossils. Upper Palaeozoic Strata. IKnottingley limestone. Gypseous marls. Bolsover limestone. Marl slate. Rotheliegende. S| "I The subdivisions are of a Coal series \ Sandstones > cla y s > ironstones, I local character, millstone coal I 1 Mountain limestone... /... C .I j grit lying at the base in many districts. e subdivisions are of a local character. Middle Palaeozoic Strata* Old red or Devonian J Limestone, sandstone, "j shale or slate.. idstone, clay, \ ) The subdivisions are of a local character, consti- tuting two distinct types. Ludlow Lower Palceozoic Strata. ( ~\ Tilestone. ( Arenaceous and argillaceous... I Y Pper I Aymestry limestone. J Lower Ludlow. ~ Wenlock limestone. [_ Wenlock Caradoc.. Llandilo.. Calcareous ................... j Woolhope limestone. L j Mayhill sandstone. Sandstones, &c .................. Calcareous, &c ................... C } Arenig slate and porphyry. J Slates, &c ......................... J- Tremadoc slate. ( ) Lingula flags. f ^ Harlech grits. < Grits and Slates ................ > Llanberris slates. ( ) Longmynd slates. Hypozoic Strata. Mica schist, including chloritic schist, talc schist, quartz rock, granular limestone, &c. Gneiss, including limestone, hornblende, schist, &c. Granitic rocks, which are not stratified, usually form the basis of the strata, and are frequently, but not by any means universally, followed by the gneiss and mica slate system. Festiniog , Bangor... STKATIFICATIOtf. 33 * Disturbed Stratification. Strata originally i>v-i. All strata, says Cuvier, in his admirable Discourse+on the Revolutions of the Globe, must necessarily have been formed horizontal; and this opinion, founded upon the admission that rocks composed of regular layers, containing rounded pebbles and organic remains of water-animals, can only have been formed under water, is supported by observation. For not only do we see at the present day the deposits of water arranged in planes nearly or exactly horizontal, but we also find the ancient strata of the earth, where undisturbed by convulsions, very nearly level. In consequence of these disturbances the strata are seldom found to be perfectly hori- zontal, but are often inclined at high angles, and in a few instances stand directly vertical. Their planes are generally continuous over large spaces, but they are sometimes broken and dislocated by faults or dykes. It is now generally admitted that the usual horizontal disposition of the strata is derived from the action of the supernatant waters which accumulated them ; and that the irregular declinations and fractures which we sometimes behold are the effects of subter- ranean convulsions, chiefly occasioned by internal expansion. The truth of these opinions Will appear from a few plain considerations. Subsequently Disturbed. Earthy matter deposited from water by tranquil subsidence, as clay and limestone, or accumulated during periods of moderate agitation, as sand and sandstone, must in general be accumulated into layers or strata, proportioned to the intervals of deposition ; and these layers, in consequence of the fluctuation of the water and the influence of gravitation, will especially tend to be horizontal. Nevertheless they must, in a considerable degree, ac- commodate themselves to the surface on which they are deposited. If the bottom be level, so will be the deposit ; if sloping, the deposit will be inclined ; but if there be a perpendicular subaqueous cliff, no deposit can fall upon its face, nor any transported materials be accu- mulated parallel to it. An originally perpendicular layer or deposit of earthy materials is obviously impossible. Whenever, therefore, we behold vertical strata, we may be quite sure that they were not deposited in that form, but have been displaced by some internal movements of the earth. Vertical strata. Abundance of instances of this remarkable position of strata may be quoted in almost any part of the world. The Isle of Wight gives us a magnificent series of strata, 1100 feet in thick- ness, reared into an absolutely vertical position ; and this effect is the more remarkable, because the materials uplifted consist of many strata of loose sands and pebbles, which most certainly have been deposited nearly level. In the western borders of Yorkshire, vertical strata of limestone range for miles parallel to the edge of the Pennine 34 DISTFEBED STRATA. Contorted Strata. chain, and turn eastward through Craven, below Tngleborough and Pennyghent, to Settle. Magnificent examples of vertical strata are familiar to those who have visited the cliffs of Savoy, or who have perused the graphic descriptions of Saussure. Contorted Strata. There are some remarkable instances of con- torted stratification very difficult to be explained without supposing the strata to have been soft at the time of the flexure. Not to dwell on inferior examples, we shall quote the magnificent pheno- mena of this kind which are seen in the valleys of Charnouni and Lauterbrun, and along the shores of the Lake of Lucerne, near Fluellen. The stratified limestones of these localities are bent with such extraordinary re- troflexions, as to imply repeated or continual operations of the most violent mechanical agency, 7 producing displacements in dif- ferent directions ; and observations along the range of the Alps prove that the whole of this chain has been the theatre of enormous and reiterated convulsions. Faults. But the most remarkable case of disturbance is when strata, either horizontal or inclined, are broken, so that on one side of the line of fracture the rocks are much higher than on the other. This difference of level sometimes amounts to 100 or even 200 yards. The succession of strata is on each side the same, their thickness and qualities are the same, and it seems impossible to doubt that they were once connected in continuous planes, and have been forcibly and violently broken asunder. The plane of separation between the elevated and depressed por- tions of the strata is sometimes vertical, but generally sloping a little. In this case a peculiar general relation is observed be- tween the inclination of this plane and the effect of the dislocation. In fig. 8, for instance, the plane of separa- tion, z Zj slopes under the de- pressed, and over the elevated portions of the disrupted strata, making the alternate outer angles z z b, z' z' V acute. In Dislocation of Strata. AGE OP DISLOCATIONS. 35 several hundred examples of such dislocations which have come under the notice of the writer of this essay, he rarely found an excep- tion to this rule. A similar law is found to prevail very generally in the crossing of nearly vertical mineral veins ; for instance, in fig. 9, a a are two portions of a metallic vein, dislocated by another vein, b b. In this case the relation of the line b b to the lines a a, is 9 10 the same as that of z to the lines b b', &c. The contrary ap- pearances, had they occurred, would have been as represented in fig. 10, and such occur in the mining district of Cornwall, together with many other singular phenomena, apparently refer- able to subterranean disturbance, perhaps complicated with other causes, but which are with difficulty reducible to any simple mode of explanation. The line of dislocation is generally distinguished by a fissure, which is filled by fragments of the neighbouring rocks, or by basalt, and is then called a dyke, or by various sparry and metallic minerals, and is then called a mineral vein. Relative Age of the Dislocation. The irregular operations by which these disturbances and dislocations were occasioned, seem to have happened at various periods during the formation of the strata. We know, for in- stance, examples of hori- zontal strata, as in figure 11, resting upon other high- ly inclined strata, which must have been forced into their unnatural position be- fore the deposit of the level strata upon them. Such a case occurs in Somersetshire, where the coal measures lie at a steep slope beneath horizontal beds of red marl. These coal measures are also greatly broken by faults, which in some cases throw or elevate the beds on one side more than seventy fathoms above ty of 36 DISTTJEBED STEATA. those on the other side. But the beds of red marl above are alto- gether uninfluenced either by the steepness of the dip or the abrupt- ness of the dislocations. Therefore the convulsions by which these effects were occasioned, happened after the deposit of the coal seams, and before the deposit of the red marl. At Aberford in Yorkshire, and at many other points along the line of the magnesian limestone between Nottingham and Sunderland, similar examples occur. At Vallus Bottom, near Frome, the moun- tain limestone is found highly inclined, below level beds of oolite ; and the mollusca which lived in the oolitic sea have bored holes into the subjacent limestone. In such cases the discordance of inclination between the superior and inferior strata is expressed by the term unconformity, and the upper rock is said to lie unconformdblij upon the lower. Principal Epochs of Convulsion. By pursuing this investigation in different situations, we find that these internal movements or con- vulsions happened at intervals during the whole period of time occu- pied in the deposition of the strata. Some of the most prevalent and remarkable cases of dislocation and unconformity are, however, observable : 1, immediately after the deposition of the silurian series ; 2, after the accumulation of the coal system ; 3, after the deposition of the oolitic rocks ; 4, after the deposition of the chalk ; and, 5th, one of the most recent probably of all, after the completion of almost all the formations above the chalk. It is not to be supposed that all even of these principal cases of dislocation can be recognized in every country ; on the contrary, the subterranean forces appear frequently to have shifted their points of action. We shall have occasion to show, while speaking of the organic remains, that there is sometimes observed a singular harmony be- tween these periods of extraordinary internal disturbance and the several epochs when the different races of animals and plants came into existence ; and it is not unreasonable to suppose, that in this manner it may be hereafter found possible to establish such a relation between the internal and external conditions of the earth, as to afford the greatest assistance towards defining the agencies which have produced changes so extensive and repeated in both. Proximity of Mountains. At present, restricting ourselves to the phenomena of elevation and disruption of the strata, we shall carry our inductions one step farther, for the purpose of proving what was before announced, viz., that these disturbances were connected with the effects of internal heat. We shall assume, then, that granitic, and basaltic or trappean rocks, and others exhibiting the same phenomena, were crystallized from a state of igneous fusion, and were, sometimes in a fluid, and sometimes in a solid state, impelled upwards from the interior of the STEUCTURE OF MOUNTAINS. 37 earth, as analogous substances are now raised fluid through volcanos, or lifted solid by earthquakes. In proportion as we approach the mountains where the greatest violence was exerted to break up the strata, raise the granite, and inject the basaltic dykes, we find the dislocations increased in num- ber and importance, and the confusion of the stratification more prevalent. The central nucleus or axis of many mountain districts is a mass, or a series of masses of granite and other unstratified rocks, from which on all hands the strata are found dipping at high angles. In such cases there can be seldom room to doubt that the elevation of the moun- tain ranges and the disturb- 12 ance of the strata, was occasioned by the same violence which up- lifted the granite. The area of granite disclosed between the opposite slopes of strata is indefinite, sometimes very large, sometimes very small, sometimes it is entirely covered over by the rocks which it has uplifted, but not perforated. The general analogy in the composition of mountains, in the strata which surround them, and in the dislocations which abound in their vicinity, prove that one common cause, the force of subterranean fire, has produced all the phenomena in question. Basaltic rocks frequently, perhaps generally, show themselves in situations removed from the granitic regions, on the flanks of moun- tains and in lower ground. In numerous instances, basalt fills up the fissure between the elevated and depressed portions of dislocated strata, and as it cannot be doubted that such a fissure would soon have been filled up by other substances, it is clear that the melted basalt was injected nearly at the same time as the dislocation was produced ; that is, that both were local effects of disturbed internal heat. Analogy of Mineral Veins and Trap Dykes. So great a general ana- logy prevails between some mineral veins and basaltic dykes, that in almost all hypotheses their origin has been assumed to be the same. Both in the same manner divide the strata ; in both the materials are crystalline, generally such as are not known to be producible from water, and arranged according to entirely different laws from those which regulate deposits from water. It seems, besides, almost inconceivable that materials of such various specific gravity and chemical affinities should be either soluble at once in water or capable of being introduced by this process at different times ; on the contrary, * 1. Primary Strata. 2. Primary Strata, 3. Secondary Strata. 38 DISTURBED STRATA. all the circumstances agree in claiming for such mineral veins the same origin as basaltic dykes, the igneous origin of which is sup- ported by the strongest possible arguments. We shall, however, discuss the history and origin of mineral veins more at large in the chapter on Plutonic products, and we shall then notice a variety of phenomena concerning them which can with difficulty be explained in the present state of our knowledge of chemistry. That part of the history of mineral veins and metallic substances in general, which is inseparable from the consideration of the rocks in which they occur, will be treated of while speaking of the several strata in succession. Disruptions of Strain, a part of the general plan of Terrestrial Adap- tations. This elementary statement of the characteristic effects of subterranean convulsions, upon the preconsolidated strata, must not be closed without noticing an important beneficial result of them upon the condition of mankind. The frequent use of the terms con- vulsions, dislocations, and other such phrases in geological treatises, may, perhaps, lead the inattentive reader to imagine that geologists are of opinion that the laminated crust of the earth, which had been constructed with so great harmony and order, was afterwards sub- jected to accidental injury, left to the violence of forces not contem- plated in its formation, so that the original plan of its fabric was destroyed by unforeseen convulsions. How false a notion is this, and how unjustly would geologists be accused of ignorance in this respect ! They know well that without the effects, which are called convulsions and dislocations, the plan of the terrestrial creation would have been incomplete, the earth not adapted, as it is, for the residence of men and the exercise of human intellect, which in all this seeming confusion can discern the progress of an uninterrupted plan, and even trace special provisions in favour of mankind. Whether we regard the mere animal nature of man, or consider him with re- ference to those glorious endowments which lift him above the brute, and enable him to contemplate the past and anticipate the future, and thus to expand his intellectual existence through all periods and over all subjects, we shall find in the broken stratification of the earth the most remarkable attention to his physical and mental constitution. Elevation of Continents How universal are the benefits which are conferred on commerce and the arts of life, by the variety of sub- stances obtained from the animal kingdom, cannot require to be stated ; for without this variety, neither commerce nor the arts of life could exist. Some faint idea of the state of a globe which did not show this variety, may be conceived by viewing the condition of the sandy deserts of Africa, and abstracting from their solitary deso- lation the assistance rendered by more favourably situated countries. VARIETY OE THE EABTH's SURFACE. 39 Now all that variety of mineral products existing in the earth, stored up in that inexhaustible repository to supply many regions through many national revolutions, would have been made in vain, and for ever hidden from the eyes of men, but for these very convulsions and dislocations in the strata. What else has raised our mountains, divided our seas, and given currents to our rivers, and by so doing established upon the globe those varieties of soil, local climate, and other conditions to which the organic wonders of creation are most evidently adapted ? What other means have been employed to pro- duce the natural, harmonious, and mutually dependent relation of plants and animals on the land, in the streams, and in the sea ? Without these disruptions, the earth would still have been uniformly covered by shallow waters ; or if some part rose above it, that must have been a barren waste, or a monotonous surface on which the living wonders of nature, according to the actual plan of creation, could not have appeared. It is, therefore, evident, that as one of the means employed by the Creator in the accomplishment of his works, the agency concerned in producing the actual condition of the terra- queous surface, and thereby regulating the leading phenomena of organic and inorganic nature, is a fit object for the special study of geologists. Exhibition of Useful minerals. It is not only in the elevation of continents, the varying height of mountains, the division of the sea, and similar striking effects, that we see the utility of the combina- tion of subterranean igneous with superficial aqueous agency. Every coal-field in the known world proves distinctly the utility of even the minor dislocations, which in our imperfect language are called " faults" in the strata. The universal effect of these " faults " is to multiply the visible edges of the strata, by bringing them more fre- quently to the surface, in consequence of which there is, in the first place, the greater chance of discovering the materials of the earth ; and, secondly, the greater facility of working them. Other advan- tages of this kind will immediately suggest themselves to the atten- tive reader. But all advantages to commerce and the arts of life sink into nothing when compared with the effect which the human mind ex- periences from contemplating the monuments of past conditions of the globe, which the uplifting of the bed of the sea, and the disloca- tions of the strata, have brought to light. All nature is a glorious book, which men are incited to read, in order to know and communi- cate with its Author, a mirror in which the Almighty and the In- finite is faintly typified in the vast and the diversified ; and in this respect geological monuments are distinct, impressive, and, in refer- ence to the earlier epochs, unique. But, if we have been conducted by long labours to some real knowledge of the internal constitution 40 INTEENAL STETJCTUEE OF EOCKS. of the globe, and familiarized with the conception of many revolu- tions of created beings on its surface, in accordance with a long sequence of mechanical and chemical operations ; and if we have thus extended the conviction of the unceasing care and comprehensive benevolence of the Divine Being to the most remote epoch which our limited intellect can reach ; all this is owing, in a certain sense, to the convulsive movements originating below the crust of the earth. Let it not, therefore, be supposed, that, because of the contracted scale of the human mind, which can see only in succession what to a greater Intelligence is contemporaneously evident, geologists are obliged to speak of certain phenomena as accidents with reference to others, which are connected therewith by ways unknown to us, that they are so blind as not to see in all the diversified operations of nature, the effects of One predisposing and directing cause. Internal Structure of Rocks. Joints in Different Rocks. All rocks, whether stratified or not, are naturally divided by fissures, passing in various directions, indepen- dent of the strata, into masses, which are of different forms in dis- similar rocks, and are accompanied by circumstances deserving more attention than has yet been bestowed upon them. The fissures or planes of parting between these masses are called joints. Most fre- quently their direction is nearly vertical to the planes of stratification, where such exist, and they divide the rock into cubical, rhomboidal, or prismatic portions, blocks, pillars, or columns. It is owing to their various direction and frequency that different rocks assume such characteristic appearances, and may thus be often and readily distinguished when seen at a distance or shadowed in a drawing. Some rocks have very numerous, approximate, and closed joints, as shale, some kinds of slate, and laminated sandstones ; in others, as limestones, the joints are less frequent and more open. In coarse sandstones they are very irregular, so that quarries of this rock produce blocks of all sizes and forms. From this cause, coarse sandstone rocks show themselves against the sea, in precipitous valleys, or on the brow of hills, in rude and romantic grandeur. The wild scenery of the Peak of Derbyshire, Brimham Crags, and Ingle- borough in Yorkshire, derives attractive features from the enormous blocks of millstone grit ; and the magnificent rocks which stand upon the hills and overlook the Vale of Wye, are composed of a somewhat similar material. In clay, vertical joints are numerous, but small and confused, whereas in indurated shale they are of extraordinary length, very straight, and parallel, dividing the rock into rhomboidal masses. JOINTS AND ITSSUEES. 41 This may be well studied in the shale, which alternates with moun- tain limestone, at Aldstone Moor in Cumberland. Rhomboidal joints are frequent and very regular in coal. In limestone the vertical joints are generally regular, and arranged in two sets, which cross at nearly equal distances, and split the beds into equal-sized cuboidal blocks; and thus the mountain limestone is found to be divided into vast pillars, which range in long perpen- dicular scars down the mining dales of the north of England. In slate districts, the joints, more numerous and more regular, per- haps, than in any other known rock, have almost universally a ten- dency to intensect one another at acute and obtuse angles, and thus to dissect whole mountains into a multitude of angular solids, with rhomboidal or triangular faces, which strongly impress upon the be- holder the notion of an imperfect crystallization, produced on these argillaceous rocks since their deposition and consolidation, by some agency, such as heat, capable of partially or wholly obliterating the original marks of stratification. Vertical joints are frequent in granite, and appear to have definite directions. The trihedral and polyhedral vertical prisms of basalt, and some other igneous rocks, coupled with their regular transverse divisions, seem to give us the extreme effect of regularity in the division of rocks by the process of condensation, from the state of igneous or aqueous expansion. General Cause of Joints and Fissures. That contraction after par- tial consolidation of the mass is the general immediate cause of the numerous fissures of rocks, may easily be proved by a variety of facts observed in conglomerates, where pebbles, and in other rocks, where organic remains, are split by the joints. According to the circum- stances of the case, this process has produced in basalt, slate, and coal, fissures so regular as to give to the rock a largely crystalline structure, but left in sandstone mere irregular cracks. From Mr. Gregory Watt's experiments on fused basalt, and some other notices by different authors, we know that a continued appli- cation of even moderate heat to a previously solidified body, may be sufficient to develop in it new arrangements of the particles, new crystalline structures, new chemical combinations, and to cause a real transfer of some of the ingredients from one part of the mass to another ; from many independent facts it is inferred, as a matter of certainty, that all the strata have locally, and the lower ones perhaps universally, sustained the action of considerable heat, since their first deposition : we seem, therefore, to be possessed of the clue which is eventually to conduct us to a thorough knowledge of the cause of the different structures observable in rocks independent of their stratification. But though heat be taken as the leading cause of these effects, it 42 INTERNAL STETJCTTJEE OF EOCKS. is by no means inconsistent to suppose that some other independent agent, as, for example, electricity, might be concerned in modifying the result. From all the recent discoveries in electricity, it appears more and more certain, that this universal agent is excited in every case of disturbance of the chemical or mechanical equilibrium of natural bodies, and it is especially, and very sensibly, excited by un- equal distribution of heat. Professor Sedgwick's suggestion with reference to Mr. Fox's electro-magnetic experiments on the mineral veins of Cornwall, that electricity was probably concerned in the original production of those veins along which it now circulates, may be justly extended to the contents of the joints of rocks ; in the study of which the writer of these remarks has found abundant reason to believe that the theory of the production of mineral veins is inseparable from that of the joints and fissures, in some of which the metallic substances are deposited. Direction of Figures. In examining with attention a consider- able surface of rock, it will be found that amongst the joints are some more open, regular, and continuous than the others, which occasionally stop altogether the cross-joints, themselves ranging un- interruptedly for some hundreds of yards, or even far greater dis- tances. There may be more than one such set of long joints, and, indeed, this is commonly the case, yet, generally, there is one set more commanding than the others, more regular and determined in its direction, more completely dividing the strata from top to bottom, even through very great thicknesses, and through several alternations of strata. For example, there is a peculiar character of joints in each of the principal strata of the mountain limestone series, lime- stone, sandstone, shale, and also in the sandstones, shales, and coal of a coal district, yet, throughout the whole of Yorkshire, all these rocks are divided by the master-joints passing downward through them all in nearly the same direction north by west, and south by east. These master-joints, called slines, lacks, bcrds, &c., are perfectly well known to the workmen, as well as some other very important yet less certain and continuous fissures passing nearly east north-east and west south-west. It is according to such joints that the experi- enced collier arranges his workings, and the slater and quarryman conduct their excavations. Now, surely nothing can be more certain than the inference, that some very general and long-continued agency, pervading at once the whole mass of these dissimilar and successively deposited strata, was concerned in producing this remark- able constancy of direction in the fissures which divide them all. The deficiency of recorded observations prevents a general development of this important subject by reference to other districts, but it is obvious that a great principle in the construction of the earth is here indicated, which must eventually have an important influence CLEAVAGE. 43 Division of Strata by Master Joints. on geological theory. In the meantime we may remark, first, that these prevalent directions of north by west and east north- east, are those of the principal mineral veins and cross courses in the north of England, and that they are also admitted to be very pre- valent in the southern and western mining countries ; secondly, that these directions are wholly uninfluenced either by the declination of the strata, or by the numerous dislocations to which they are liable. Whatever be the direction of the dip, how frequent soever the faults, the lines of the great joints are the same. These lines are frequently the cause of particular courses in rivers, long scars on mountain sides, and subterranean channels for water. Faults, and dykes, and mineral veins very frequently pass along them, and there is little doubt that the diligent study of them will be found to throw a new light on some of the most mysterious phenomena of Limestone. Cleavage. There is yet another structure not common to all rocks nor confined to a given geological age. Though most frequently manifested among the primary strata, it is sometimes observable in others of a later date. This structure is called cleavage, and it con- sists in a peculiar fissility of the rocks which are affected by it, parallel to a certain plane, which almost always cuts at a considerable angle the plane or curved surfaces of the stratification. In fig. 14, which represents a mass of rocks in which this definite fissility is de- veloped, B B is the surface (curved in this instance) of one bed of the stratifica- tion; J is on the plane, here supposed vertical, of a joint ; c is one of the planes of cleavage, cutting the surface of stratification B B in s-s. Parallel to this plane c, the mass of rock here repre- sented is cleavable by art, and is often actually cleft by nature, into very thin and numerous plates, which, when of suitable quality and reduced to proper size, constitute the roofing slate of our houses. The edges of these plates may be traced with care on tha vertical surface of the joint J, and the sloping surface of the bed B, and are represented in the figure by fine lines. 14 44 INTERNAL STRTJCTUBE OF EOCKS. It will be observed that these lines do not cross the bed marked g. This is supposed to be a hard grit or conglomerate, and such rocks are sometimes only in a slight degree affected by the cleavage, which is perfect above and below them, in fine grained more argilla- ceous strata. Certain small joints, however, often, and, in other cases, numerous cleavage planes, do cross sandstone beds, and then it is worthy to be observed that the cleavage and joint planes in these beds are not parallel to the general cleavage, but meet the surfaces of stratification, as in this figure, at angles more nearly approaching to a right angle. At I the cleavage crosses nodular limestone or ironstone, and in these irregular layers it becomes irregular, curved, and confused. On the surfaces of stratification the cleavage structure is frequently traced in narrow interrupted hollows and ridges ; these surfaces have in fact been folded, or plaited, or puckered by the force which occa- sioned the cleavage ; and the little folds thus occasioned, are trace- able across shells, trilobites, &c., which are thus more or less altered in figure. On a careful scrutiny of these shells and trilobites, we find that they have been compressed in one direction, so that a semicircular shell (orthis), whose hinge line lies parallel to the cleavage edges on B, is found to be altered to the figure a ; another whose hinge line lies across these edges, assumes the shape of b ; and a third whose hinge line is oblique to the edges of cleavage becomes distorted as c. To make this more clear the letters B B are represented as having undergone the compression in question. When, as sometimes happens, there are on these surfaces shells and pebbles, too solid and firmly compacted to yield to the cleavage form, they are not altered in figure, but the cleavage laminae in the mass around them are altered a little in direction. It is observable, also, that some change of direction frequently occurs when the cleavage is passing from one bed to another of a different de- gree of solidity, though in the middle of each bed the cleavage-planes may be parallel. But it also happens, and in some tracts of country, (e.g., the district of Cork), it is a common occurrence, the cleavage planes are not parallel in contiguous beds, of unlike quality, but appear as in fig. 15. The cleavage plane being most oblique to the bedding is the softest and most argillaceous strata. One general relation appears between the stratification and the cleavage a relation arising from the displacement of the strata by axes of elevation and depression. Parallel to these axes is the " strike" CLEAYAGE. 45 or horizontal line in the surfaces of the strata ; if this be taken on a great scale and the " strike" of the cleavage (similarly denned) be compared with it, the direction of each is found to be the same, or nearly so ; in other words the cleavage edges on the surface of the strata are horizontal lines (s-s in fig. 14). The direction, then, of the cleavage in a given district is dependent in a general sense on that of the axes of movement in that district ; but the inclination of the cleavage has no necessary known relation to that of the i strata ; beyond this, that the dip of the strata being moder- ate, that of the cleavage is usually greater. In a coun- try where the strata are much undulated, the cleavage may be and mostly is in parallel planes. Thus in tig. 16 the strata are synclinally and an- ticlinally bent, but the cleav- age is vertical, or nearly so. Local Changes of Internal Structure. "VVe must defer till a later page the theoretical considerations which arise out of these,* and some other valuable data, which have been lately collected by Mr. Sharpe and Mr. Sorby, but though a little out of place we cannot forbear to add here a short notice of facts known in Swis- serland, which distinctly prove one of the effects of heat upon common argillaceous shales, to be the alteration of its structure, so as to give a real vertical cleavage to a mass of horizontal Iamina3 of clay, as well as that induration which belongs to slate. The has shales of the Alps are so altered by proximity to the igneous rocks of that region, that in several places in and near the Valley of Chamouni, they are commonly mistaken by modern tourists for genuine slates of the primary system, and were always described as such by the older writers. How plainly does this teach us that the joints, cleavages, and other peculiarities of their structure, not pro- duced in rocks by water, nor coeval with their deposition, have been occasioned chiefly by the agency of pressure, molecular rearrangement, or other secondary effect of disturbances generated by subterranean heat. What powerful aid does this generalization give toward explaining many phenomena heretofore despaired of in geology ! Mineral Composition of Strata. Formations in Water. Water is both a chemical and a mechanical * These observations on cleavage are all derived from personal observation, and have been mostly published, in earlier works by the author. Encyclo. Metrop. 1833. Guide to Geology, 1834-6-54. Treatise on Geology, 1853. Brit. Assoc. Report, 1813. 46 MIKEEAL COMPOSITION. agent, and a receptacle of life. Under different circumstances at certain temperatures, by the help of other ingredients, as acids or alkalies, various mineral substances are dissolved in it. When, by evaporation, loss of heat, or a change in the composition of the liquid, these substances are no longer capable of remaining in solution in it, they separate in a crystallized form, or fall down, and the sediment which they occasion is called a precipitate. By such processes lime, magnesia, and other earths and metallic oxides, are first dissolved in water, and afterwards separated from it. We find these processes in the present order of nature, chiefly con- cerned in producing calcareous marls and irregular accumulations of limestone, in lakes and in the course of certain streams and at the mouths of some rivers. So in more ancient times, the most abun- dant chemical deposit from water was limestone. The mechanical agency of water is manifest at the present day in removing materials from one place and depositing them in another. Thus pebbles and sand and clay are transported by the tides and by rivers, and accumulated in low situations in regular layers, minia- ture representations of those thicker strata of the same ingredients, which compose the crust of the earth. And as at the present day some materials are transported farther by water than others, and consequently more rounded by attrition, so the materials of the inte- rior strata are likewise more or less worn and rounded, in proportion to the distance they have travelled and the friction they have suffered. In many situations chemical and mechanical products are occa- sioned successively by the same waters, just as in the older strata limestones and sandstones alternately prevail. We see, therefore, that the ancient deposits from water, which form layers several miles thick around a great part of the globe, are not essentially different except in degree, from the lesser deposits now formed beneath the tides from the sea and the streams from the land. The chemical stratified deposits are principally limestones, com- posed of carbonates of lime and magnesia, arid salt rocks characterized by chloride of sodium. This is not the place to discuss points of theory, and we shall therefore speculate no further at present on the origin of these deposits than to say, that the quantity of lime now held in solution in sea water, is subject to daily waste by the pro- cesses of life, and to daily renewal by the afflux of streams from the land. The innumerable tribes of zoophyta, mollusca, and other ver- tebrata, obtain the carbonate and phosphate of lime necessary for their corals, shells, crusts, &c., from the salts of lime in the sea, and these salts are supplied by currents from the land, which have derived lime from the old calcareous rocks. These rocks are found to be almost wholly composed of shells, corals, crusts, &c., and thus we perceive as a very general fact, that it is less by direct chemical re- OF STEATA. 47 agencies, than by vital energy and the decay of organized fabrics that thick calcareous masses of every age have been and are formed in the sea. The mechanical deposits, or strata, composed of earthy materials, are distinguished by the coarseness or fineness of the ingredients and by the nature of these ingredients. When the materials "are of un- equal fineness, and some of them are large, rounded pieces, the rock is called a conglomerate : pieces not so large constitute a sandstone, very fine particles containing some alumina clay. The following scale will convey some notion of the gradations of size in the ingre- dients of mechanical deposits : Mixture of clay and sand .............................. Sandy clay. Sand with some clay .................................... Argillaceous sandstone. Small fragments of hard siliceous minerals ........... Sand, sandstone. Sandstone including pebbles .......................... Millstone grit. Large pebbles united by sandstone or clay ........... Conglomerate or puddingstone. Pebbles disunited ....................................... Gravel. Stony fragments reunited .............. ................. Breccia. ingredients of Mechanical strata. Considered with reference to the nature of the ingredients which compose them, mechanical strata form another scale. Thus gneiss, one of the oldest of these strata, is a compound of the same ingredients as granite quartz, felspar, and mica ; but these minerals, instead of being amalgamated (so to speak) together by crystallization, are accumulated in successive laminae more or less regular, and more or less soldered together. Some varieties of gneiss, therefore, differ from micaceous sandstone less than is commonly imagined, and often other varieties occur, which have so slight a lamination, and so much of crystallization, as to justly bear the name of granitic gneiss. Sandstone is generally an aggregate of small fragments, or worn crystals, of quartz, with or without any argillaceous, or calcareous or irony cement in the interstices, with or without any mica in the partings. Sometimes it very evidently contains rolled and broken pieces of crystallized felspar, such as that which fills the Pyramids around Mont Blanc, or the granite of Cumbria and Scotland. There is, therefore, every reason to conclude, that coarse sandstones like the millstone grit, have been derived from the waste of ancient tracts of granite. Some beds of sandstone at Oban in Argyleshire appear to have been formed from the granular fragments of disintegrated green- stones. Sandstones sometimes extend over vast districts, and during the whole range are characterized by some remarkable mineral ingre- 48 MINEKAL COMPOSITION. dient ; as for instance, the green sand of England, France, and Swis- serland, which is distinguished by the presence of glauconite, a pecu- liar green mineral, a silicate of iron. Conglomerates, on the other hand, are generally constituted of fragments from the neighbouring mountains. Thus the red sandstone of the Vosges mountains contains quartz pebbles derived from the slate rocks of the vicinity ; the old red conglomerate of England varies in its composition according to its locality ; that of Hereford- shire contains much quartz, that of Cumberland is filled with pebbles of slate. whole Series of Strata. The whole series of stratified rocks then consists of alternate deposits of limestone, sandstone, and clay, with few layers of coal, rock salt, flint, iron ore, &c. The modes of alter- nation are different in different parts of the series, and in different situations. Thus the Siberian limestones are sometimes enclosed between beds of slate, the carboniferous limestone alternates with sandstone and shale, the lias limestone lies in marly clays, the coral- line oolite is enveloped in calcareous sandstone. Generally, the differ- ent strata are distinguishable by their mineralogical characters ; but not always. When the circumstances of the deposit were nearly similar, as in the accumulation of the carboniferous limestone and some of the oolites, the strata are remarkably alike ; and often par- ticular beds of one rock are scarcely to be distinguished from beds of another rock. Thus some beds of lias are scarcely to be known from some calcareous layers connected with the Bath oolite, while other portions of the same rock strongly assimilate to the carboniferous limestone. The old red sandstone and the new red sandstone forma- tions are very much alike ; it would be difficult by mere mineralogi- cal methods to discriminate the clays which separate the oolites, and many sandstones of very different epochs are almost undistinguish- able. Hence we may infer that nearly the whole series of strata is the result of many repetitions of similar mechanical and chemical agencies operating in similar waters. Alternation of Beds. When sets of strata are in contact, as for instance limestone lying upon sandstone, it often happens that while L-^aw or agnation tf **. ^ Umestone above, and the sand- stone below, are unmixed with other matter, there is a middle set of beds composed of alternate lay- ers of the sandstone and limestone. Thus, let a be the coralline oolite caicartout Grit. of England, and b calcareous sand- stone beneath; the middle beds a' a" b' b" are alternately oolite and sandstone. In such a case, therefore, the two strata are said to exchange beds, BEDS AND DEPOSITS. 49 or to be subject to alternation at their junction, and the phenomenon seems to have been occasioned by temporary cessations of the depo- sit of sandstone during the commencement and progress of the deposit of limestone. Gradation of Beds. In other instances, the two strata pass into one another by imperceptible gradation ; as for instance, the Oxford clay of the Yorkshire coast graduates into the cal- careous grit above so com- pletely, that the bluish colour of the crumbling shale below is shaded off without any hard line into the yellow solid beds of grit above. See fig. 18. 18 In either case it seems quite evident that no considerable break or interval of time happened between the different contiguous depo- sists, one bed was no sooner formed than another was laid upon it ; and by careful study of these phenomena it appears that, bed by bed, and rock after rock, the whole series of strata, even to miles in thick- ness, were successively and almost unremittingly accumulated, and buried the shells and other organic beings, which were then living in the water, or drifted into it from the land ; such are, therefore, the best witnesses of the lapse of time, and of the changing condition of the land and water during the deposition of the strata. Proportions of Chemical, Vital, and Mechanical Deposits. Assum- ing limestones to be of chemical or vital origin, and sandstones, clays, &c. to be mechanical deposits, and putting for the present out of consideration the detached organic remains which so much abound, especially in calcareous strata, we shall be able by compari- son of the thickness of the several rocks to present a tolerably accu- rate notion of the relative proportions of chemical, vital, and mechanical deposits. The greatest obstacles to accuracy exist amongst the hypozoic strata, whose thickness is exceedingly uncertain, and the original condition of the rocks often hardly to be determined at all. If we take our examples of these strata from the Island of Great Britain, it may, perhaps, be found a sufficient approximation to the ratio now sought to say the mechanical to the chemical deposits of water are : In Hypozoic strata 100 to 1. In Palaeozoic strata 20 to 1. In Mesozoic strata 4 to 1. In Tertiary strata 10 to 1. In these comparisons regard is had to the different proportions which prevail in different districts. They would be very different E 50 MIKEBAL COMPOSITIONS. estimates for tertiary oolites in the Isle of Wight, and in the Basin of London, and for the oolites near Bath and near Whitby. From this comparison it would appear that the ratio of chemico- vital to mechanical strata is greatest amongst the secondary deposits, and least amongst those of the primary periods ; a circumstance on which depend principally the well-marked general characters of the secondary series of rocks. It should, besides, be observed, that cal- careous matter very finely divided exists in nearly all the sandstones and shales of that series, and sometimes so abundantly as to change, locally, lias shale into argillaceous limestone, and calcareous grit into arenaceous limestone, or coarse oolite. In secondary strata, the great and prominent masses of limestone almost invariably attract the attention and direct the classification, and thus it happens that while numerous layers of clay and sand pass nearly unobserved, or are merely noticed as interpolated beds, almost every calcareous bed has its characteristic local name. The almost universal diffusion of calcareous matter through the mechanical strata of this large class, combined with the greater regularity and persistence of the lime- stones, generally impresses on the attentive observer a peculiar theo- retical notion as to the cause. He soon learns to consider the operations by which sandstones and clays were accumulated as of short duration, and intermitting action, like the periodical floods of a river, or some less regular inundations ; while the production of limestone is regarded as the result of one continuous and almost un- interrupted series of chemical changes. This opinion, strengthened by the curious gradations between the calcareous and the sandy or argillaceous laminae, and by the frequent alternation amongst even their thinnest portions, derives very plausible arguments from the distribution of organic remains through the, several strata. In some cases these teach us plainly that sandstones, even of great thickness, were the products of temporary and often of very local floods, which swept down from the land the scattered spoils of the animals and plants then in existence ; but, tried by the same tests, the calcareous rocks appear to have been of slower and more equable production, in clearer and more tranquil waters. Is not this exactly in harmony with the present system of natural operations ? The pebble beaches of our actual shores and the gravel and sand banks of our shallow seas may be compared with the often narrow and irregular sandstones and conglomerates of every earlier age ; the finer clays which fill the broader and deeper hollows of our seas, because such fine sediments are held long in suspension by water, are quite similar in position to the older argillaceous deposits ; and our modern coral reefs and the shell beds which accompany them, produced in clear pelagic waters, unmixed with sediments from the land, are in many respects exactly the representations of the old limestones of Wenlock, Bakewell, Calne, and Orford. PEESEEYATION OF OEGAtfIC EEMAINS. 51 CHAPTER III. ELEMENTAEY YIEWS IN PALAEONTOLOGY. State of Preservation of Organic Remains. What Organic Remains occur in the Earth. The fossil remains of ancient plants and animals have been the theme of admiration for the learned and the vulgar in every historical age. The difficulty of understanding how the shells of the sea and the plants of the land could be enclosed in hard rocks, in prodigious abundance and of ex- quisite beauty, led Plot and Llwyd, and even partially Ray and Lister, together with some continental writers of eminence, to adopt strange hypotheses. Plot advanced the extreme absurdity that these beautiful monuments of the ancient condition of the earth had in fact never been shells or plants, but were merely lusus naturce, de- ceptive resemblances produced by some plastic power in the interior of the earth. Swift well ridicules this notion of lusus naturce in his Voyage to Brobdignag. This ridiculous fancy has long since become obsolete, and the " formed stones " dug out of the bowels of the earth are now recog- nized as the original inhabitants of its primeval land and water. The differences of condition between them and analogous living objects, the mode of their conservation, the manner of their distribu- tion in the earth, the relative periods of their existence and destruc- tion, constitute a vast and crowded field of research, through which many avenues are already traced toward the secret agencies which were employed in the formation of the earth. Terrestrial plants abound in certain strata, especially in the coal districts, where the seams of coal are nothing but vast layers of vegetables which grew on the marshy ground, or were swept down into estuaries or lakes, there covered by sand and clay, and changed by chemical decompositions. Zoophytes, both stony and flexible, many of them belonging to genera now in existence, fill our limestone rocks with their most delicate and beautiful organization; with them lie abundantly columns of crinoidal animals, and crusts and spines of echini. Molluscous animals are now the most numerous of all the tribes of beings which overspread the bed of the sea, and their shelly cover- ings are also the most abundant of all the organic fossils. Of the articulated animals, the most abundant remains are lob- sters and crabs, and other Crustacea, analogous to existing types ; besides trilobites and others to which nothing similar has yet been 5Z PRESERVATION OF ORGANIC REMAINS. found in the modern ocean. Fossil insects are rare ; but their num- ber has been much augmented of late years by the researches of Mr. Brodie. The valuable information which they yield concerning the ancient land, now includes the eras of the coal formation, the lias, oolites, wealden, and tertiary strata. What Portions of the Original Structures are Preserved. No one acquainted with the structure of the invertebral animals previously mentioned, can view their crusts, shells, and other hard appendages in the fossil state without being struck on the one hand with the wonderful perfection of all their minutest organization, and on the other with the uniform and almost total absence of their soft parts. The bodies found " petrified" in the rocks were for the most part originally durable. Similar substances are now capable of conserva- tion in our cabinets : but the softer animal parts which they pro- tected the muscles, the viscera, and even the ligaments have al- most uniformly disappeared. Hence it appears a just conclusion that the process of petrification, the substitution of mineral for animal matter, was slow and gradual. There is, however, some further information to be acquired by careful scrutiny. In argillaceous and finely arenaceous strata, we have the ligaments of veneridae, cardiacese, and unionidse preserved ; sometimes in the clay of Christian Malford, and the limestones of Franconia, we find the arms of cephalopoda ; in the chert of Tisbury Mr. Charlesworth finds the branchial struc- ture of trigonia. The same result follows a similar examination of the fossil reliquiae of vertebral animals. For though we find in tolerable plenty the bones, scales, scuta, and teeth of fishes and reptiles, the soft parts are usually deficient. In the chalk, Dr. Mantell found the swimming bladders of fishes. The bones of birds are excessively rare in mesozoic deposits ; only their footprints remain in older strata. Mammalia occur but rarely in mesozoic strata (Stonesfield, Purbeck), and are only plentiful in the later tertiary rocks. in what State Embedded. In consequence of the decay of the softer parts, many of the hard parts of animals are found disjointed and separate. Crusts of lobsters, bivalve shells, vertebral columns, origi- nally bound together by perishable ligaments, are very frequently found in detached portions, precisely as happens to similar objects at the present day ; and generally this is all the injury they have sus- tained. The delicate striae, sharp spines, and other ornaments, are usually so well preserved, that no one can believe that they were ever removed far from their native haunts. They were, in fact, quietly buried on the bed of the sea ; living or dead, entire or decom- posed, just as such beings are found at the present day, when by any method the bed of the sea can be examined. EMBEDDING SUBSEQUENT CHANGES. 53 And just as at the present day, where currents run strongly in the sea, shells are worn by friction in the sand, and by beating against one another, and trees carried down by rivers are scattered in frag- ments ; so in certain of the old strata we find similar proofs of rapid currents from the land, and temporary turbulence in the primeval ocean. All the accidents of imperfection and disunion of parts happened, of course, before the organic bodies were enveloped in the earthy deposits. Subsequent Changes of Composition. The changes by which they have been converted to petrifactions did not, probably, commence till after they were thus enclosed. These changes in the substance of the fossil reliquise are different according to the original nature of these bodies, the kind of matter in which they are enveloped, and the other circumstances by which they were surrounded. We shall make some remarks 011 the conservation of the principal classes of organic fossils in the different kinds of matter. in Plants. Dried vegetable substances may be considered as com- pounds of carbon, oxygen, and hydrogen, with small and variable proportions of other substances. Carbon (C) 40 to 55 percent. Oxygen,.... (0) 40 to 50 Hydrogen, (H) about 5 The carbon obtained from the carbonic acid of the atmosphere is combined in the living plant with oxygen and hydrogen, in such atomic proportions of these two gases as we find them in their most frequent combination water. Death releases the elements from this combination ; freely exposed to the atmosphere, woody fibre under- goes eremacausis,* gives off carbon and water, or the elements of water, and in such a manner that the relative proportion of water to carbon remaining in the wood diminishes, the carbon relatively increases. Two atoms of hydrogen and two of oxygen pass away for every atom of carbon. Thus, if oak wood consists of C 36 H 22 O 22 , it is changed by the process of decay to humus, which consists of C 35 H 20 O 20 ; and the change continuing, it becomes C 34 H 18 O 18 ; and by continuing the process, we may at last have C 25 H 0. The oxygen and hydrogen seem, in many cases, to have vanished, but the carbon generally remains, and is either almost pure, as in some kinds of anthracitic coal ; mixed with some residual oxygen and hydrogen, and containing some special oils and resins, in jet and most coals ; mixed with carbonate of lime, as in the remains * Destruction or decay by slow action of oxygen (?g/*<>f , gradual; *w British Fossils. Birds 8 | Mammalia 52 J British Fossil Species. Considered according to their situations of life, the British organic remains present the following results : fPlants 500 and more. I Shells 60 rr , i Insects 19 lerrestnal < -r, .., | Reptiles 15 Birds 8 Mammalia 52 fPlants 20 I Shells 120 Fresh Water and Estuary 1 Crustacea 14 I Fishes 10? ^Reptiles 12? Plants 10 ZoophytaandBryozoa... 370 Radiaria 260 Foraminifera 82 Shells 2380 Marine Crustacea 150 Annelida 79 Cirripeda 50 Fishes 526 Reptiles 66 Mammalia ? European Fossil Species. Such are the numerical relations result- ing from a comparison of the extinct British species of animals and plants on the one hand, with the recent organic beings of Britain, and universal living races of the globe on the other. These relations would doubtless have been considerably modified, had we found it possible to introduce accurately all the European species of fossils. But this task, owing to the still imperfect state of discovery on the subject, but far more to the unhappy confusion of synonyms, is at present hardly practicable. However, not wholly to neglect so im- portant a datum, we shall reprint, from information conveyed to us by Brongniart, Deshayes, Groldfuss, Dalman, and other writers, a numerical statement, drawn up in 1830, of the most remarkable and ascertained European fossils, and put them in comparison with a corresponding estimate, formed at the same time, of the ex- isting species. In each column the numbers are now greatly aug- mented : 62 DISTEIBUTION OF OEGATsIC BEMAINS. Remains of Animals. In the strata. Living estimated. Mammalia, including Cetacea... 152 1100 Birds few 5000 Eeptiles 71 2100 Fishes 183 5500 Insects 74 100,000 Crustacea 104 500 Annulosa 104 1000 Cephalopoda 788 100 Pteropoda 5 50? Gasteropoda, Zoophaga 107 1700 Phytophaga 773 1408 Conchifera, Brachiopoda 379 40 Mesomyona 515 350 Plagimyona 1132 1400 Tunicata ! Radiaria 278 1000 Polyparia 476 1000 6036 \ 22190 Plants 540 52000 Number in Different Rocks. The animal and vegetable fossils are very unequally distributed. For while some rocks are wholly filled with shells, others are absolutely devoid of them. Thus the forest marble and coarse upper beds of Bath oolite are composed of little else than shells, while the sandstones of a whole coal district may contain not one. This does not depend either on the absolute depth from the surface of the earth at which any rock may be found, nor yet upon its relative depth in the series of strata, but it is a circum- stance established by experience, and of which some of the causes remain to be determined. The following table exhibits the propor- tionate number of species of fossils in all the principal strata of Yorkshire, arranged according to their order of superposition : No. of fossil Ratio. Thickness Species. Species. Feet Chalk 500 43 1 to 12 Gault of Speeton ) -_ / 67) Kimmeridge clay ] 15U \ 5f Upper calc grit 60 5 1 to 12 Coralline oolite 60 125 2 to 1 Lower calc grit 80 48 1 to 2 Oxford clay 150 36 1 to 4 Kellowayrock 40 60 3 to 2 Cornbrash 5 37 7 to 1 Upper carbonaceous series 200 30 1 to 6 Forest marble slate \ Qn co Q i Bath oolite / Lower carbonaceous series .. ,500 21 1 to 24 NUMERICAL PEOPORTIONS. 63 No. of Fossil Ratio. Thickness. Species. Species. Feet Loweroolite 60 91 3 to 2 Lias and marlstone 850 115 1 to 7 New red sandstone 1000 none Magnesian limestone 215 30 1 to 7 Coal system 3000 100? 1 to 30 Mountain limestone .2500 400 1 to 16 Old red sandstone none Silurian and Cambrian system 6000 20 1 to 300 It is necessary to remark, that the proportions derived from the preceding table would apply only in a general way to the same strata in the south of England, for there the number of organic re- mains in the chalk is, at least, triple of that in the table, the thick- ness remaining the same, while the mountain limestone is consider- ably less rich in fossils. In the counties immediately to the north, the magnesian limestone is far richer in fossils ; to the southward it is less rich. Still less is such a table to be viewed as a representative of the results of researches on the continent, for there the new red sandstone formation contains a large suite of organic remains, both vegetable and animal, while neither have yet been found in this rock in England. Fossil and Recent Species Compared. We shall now Consider what are the kinds of fossils which are contained in these various strata ; in other words, in what order of distribution the fossils are arranged in the earth. A great difference between the present system of nature, and that of which the relics are preserved in the earth, is obvious to any one who considers the relative proportions of the different classes of each. But the most decisive proof of the enormous changes which have happened in this respect is found by a minute comparison of the families, genera, and species. For except in the superficial and com- paratively modern accumulations from fresh-water lakes, floods, or tides, and in the most recent of all the strata, scarcely one specimen of all the thousands of existing kinds of plants or animals is found buried in the earth. The earth contains the records of an ancient system of living nature, which in its great outlines was calculated much like that which we now see in operation ; but of which all the details were different. The ancient waters nourished saurians, but they were not our crocodiles ; fishes which are generally unlike the finny tribes of the existing era ; innumerable shells planned on the same general principles, but executed to different patterns. The plants and the animals of the ancient continents performed the same relative func- tions as the vegetable and animal races of to-day, and formed part of a similar combination, but, as the circumstances of the globe are now 64 DISTRIBUTION OF ORGANIC REMAINS. not the same as then, the forms and structures of its plants and its animals are adapted to the difference. Successive Eras of Fossil Tribes. But it must be obvious that to view the whole multitude of extinct animals and vegetables as the products of one ancient era, to confound together all the various different strata which were successively the beds of the ancient seas, would be to destroy the meaning of all the monuments which nature has preserved of the long periods and successive developments through which our planet passed before the completion of its present beautiful arrangement. Each stratum was successively the bed of some ancient ocean or lake, and the remains with which it is filled were the creatures then living in the waters or growing on the land. Each stratum, therefore, belongs to a particular period ; it is the museum or repository in which nature has preserved the plants and animals of that period ; and the geologist, no longer confined to the mere comparison of recent and extinct species, finds in the earth the proofs of many successive creations and abstractions of life, many systems of nature ; and by strict analogy and ample induction looks back through a long vista of revolutions, till the view is lost in the dimness and distance which hide the remote epoch, of which no evidence remains to show that the earth was then inhabited by living creatures. Terrestrial and Marine Fossils not usually abundant together. The organic monuments of ancient nature are either of marine, of fresh water, or of terrestrial origin. The corals, and by far the greater number of shells, are marine, certain strata are filled with lacustrine reliquiae, and others with the spoils of the land. There is in general the most remarkable and constant distinction and contrast between the rocks which are filled by marine remains, and those which enclose terrestrial productions. Calcareous strata generally are the most richly filled with the spoils of the sea, zoo- phytic, molluscous, and vertebrated animals ; but they rarely contain terrestrial plants. Sandstones and shales, on the other hand, are almost the exclusive repositories of terrestrial plants, but unless they are in some degree calcareous, they more rarely contain marine exuviae. The reason seems to be that the calcareous strata were deposited slowly and in tranquillity beneath the waters of the sea, and thus enveloped the dead and decaying animals of the ocean ; while, on the other hand, the sandstones and shales were more rapidly aggregated, in water too agitated to favour the accumulation of marine reliquiae. When we find in them few or no traces of land plants, we may perhaps presume that the currents to which they may owe their origin were marine, but when they are charged with ferns, equiseta, and other ter- restrial plants,and marked bybandsof cyprides,unionida3,andpaludinse, it seems evident that land-floods contributed to their accumulation. LIMESTONE, SANDSTONE, SHALE, ETC. 65 Oceanic Deposit of Limestone. The deposition of limestone by chemico-vital precipitation, would probably happen over a large portion of the bed of the sea, and be abundant in proportion to the depth, clearness, and tranquillity of the water ; hence the strata of limestone would thicken toward the centre of the oceanic basin. They would also be of more uniform texture, and perhaps of purer com- position, in that direction ; and since, from accurate observations of the habits of recent marine animals, it appears that they do not multiply so much in the darkness of very deep waters as nearer the shore, we may conclude that fewer marine shells and corals, &c., should be found near the central points of the basins of strata. How remarkably all these conditions agree in the limestones of the Alps, which appear to have been uplifted from deep water, needs only to be mentioned. There, the rocks corresponding to our oolite, are vastly thicker, more dense, and incomparably poorer in shells, than the same strata toward the borders of the European basin. And if, in proceeding through France to the Alps, we stop to consider the Jura, we shall find its oolites, in respect of thickness and hardness, and quantity of shells, of an intermediate character. Littoral Deposits of Sandstone, Shale, &c. On the other hand, sand- stones and clays, being mechanical deposits from agitated water, should of course be most abundant along the margins of the ancient sea, and at the mouths of ancient rivers, where the strongest move- ment of the waters happened. Sandstones are essentially littoral and shallow sea formations, and should be found thickest, and most numerous, and most varied in character, towards the borders of the basin, where the limestones are the thinnest. And as the forces of tides and currents, however powerful, are irregular and limited, the me- chanical aggregates which they occasion must be, and in general are, more confined and irregular than the wide chemical deposits of the sea. This supposition likewise agrees perfectly with what we observe in comparing the oolitic system of the Jura and the Alps with that of northern France and England ; for the clays and varied sandstones which diversify this system in the latter countries, and separate it into many distinct groups, are scarcely to be traced in the Alps, and only partially so in the Jura. Another case in point is furnished by the carboniferous limestone series of England. This limestone in the south of England is so little divided by mechanical strata, that in the Mendip hills, near Bristol, and around the forest of Dean, it is commonly supposed to be one thick rock. In the north of England it is much and evidently divided, and the number and thickness of the partings of shale and sandstone, and coal, increases continually northwards, while the total thickness of the limestone beds grows less and less. At the same time the 66 DISTRIBUTION OF OEGANIC EEMAINS. organic remains seem to become, if not more numerous (a point as yet difficult to be determined), certainly more varied in form. The oolitic system of England presents us with another valuable illustration of the same doctrines. The oolites of Somersetshire, Gloucestershire, and Lincolnshire form a long range of hills, and are only, and that not universally, divided by partings of clay and marly limestone. But as we advance into Yorkshire we find these spaces augment, and the widening in- tervals filled up by thick deposits of sandstone, shale, plants, and coal, which predominate so much in the section as almost to obli- terate the separated, attenuated, and deteriorated limestones. These, however, are filled perhaps even more than usually with marine exuviae. The concretionary or oolitic structure is, perhaps, more decided and constant toward the borders of the strata. It becomes irregular, and at length fails in proportion as the limestone is mixed with earthy impurities. At the extreme northern range of the degraded oolitic system in Sutherland, this structure is nearly lost ; it is irre- gular in the impure limestones of Yorkshire, becomes perfect in the homogeneous strata of Lincolnshire, Gloucestershire, and Somer- setshire, assumes more compactness in the Jura, and changes to dense limestone in the Alps. This is exactly what, a priori, would be expected to happen. Amidst the turbulence and admixture of the littoral deposits, a pro- cess so similar to crystallization could happen but seldom and un- equally, there would be a point at a certain distance from the shore at which the disturbance would prevent regular crystallization, and yet would permit of concretion through the calcareous sediment, and still further the limestone would be more compact and subcrystalline. Coarse conglomerates, for similar reasons, would be most abundant toward the shores and more local than the finer sandstones and clays, which also would be most likely to contain the remains of plants, as these might be long suspended in the unsettled water, and be trans- ported along with the finer matter. The distinction here insisted on between conchiferous and phyti- ferous rocks is so important, that we must, in speaking of the distri- bution of organic remains in the earth, consider them apart ; and while from the former we deduce the ancient condition of the sea at several epochs, the latter will furnish us with analogous data from which to reason on the state of the contemporaneous dry land. We shall commence with the Marine Fossils, and investigate the manner of their distribution under two general heads : 1st, their relation to the chemical and mineralogical composition of the strata ; 2dly, to their relative antiquity. Analogous Fossils in Similar Bocks. If the marine fossils are NATUEE AND AGE OF EOCKS. 67 distributed in the rocks according to their chemical nature, we shall find that similar rocks contain analogous fossils. This is certainly the case with respect to the zoophytic animals, for these are almost confined to the calcareous strata. Corals, and various animals of the class radiaria, abound in the silurian limestone, carboniferous lime- stone, oolites, and chalk. The remarkable brachiopodous bivalves, as spirifera, producta, pentamerus, terebratula, are also by far most abundant in the cal- careous rocks. Gryphsere and smooth oysters are found in the argil- laceous strata of the south of England, from the lias upwards to the chalk. The organic remains of the different limestones of the oolitic for- mations have very remarkable general analogies. Thus the inferior oolite and the coralline oolite, the fuller's earth rock, and the corn- brash, hold very many closely analogous species. In reasoning on this circumstance, it must be remembered that the distinctions of the oolitic system in England are in some degree local, and probably dependent on the littoral character of the deposits, and that in other parts all these subordinate strata coalesce together into one hardly divisible mass of oolitic limestone. Repetitions of similar groups of fossils indicate the recurrence of similar physical conditions, and teach us very curious truths regarding the old land and sea, and sometimes determine the continuity of river and estuary action through long geological periods. These are the most remarkable instances of the association of cer- tain organic forms with certain chemical compounds ; they are im- portant data to support the opinion that, generally, fossil remains lie near the places where the animals perished. But it is evident that these few analogies by no means establish a general law. On the contrary, when we proceed to consider in this point of view a large number of species, the resemblance between the organic contents of one limestone and those of another of considerably different age, is very slight and shadowy. And as no other strata than the lime- stones exhibit it in a striking degree, it is evident that some other cause than the chemical composition of their repositories has regu- lated the inhumation of fossils. Different Fossils in Strata of Different Age. That cause, the relative antiquity of the strata, is the subject of our next examination. That a strict connection does really obtain between the age of a rock and the organic remains which it contains, is made evident by comparing a few well ascertained facts. The mountain limestone of the north of England contains about 500 species of animal remains ; the lias, 120 ; and the chalk, 50. Now, of all the 670 species contained in the mountain limestone, lias, and chalk, respectively, there is not one which is found in two 68 DISTRIBUTION OF OEGANIC EEMAINS. of these rocks. Neither of these strata contains a single fossil which is found in either of the others. Between the era of the formation of the mountain limestone, and that of the lias, the whole animal population of the sea had been entirely changed ; and a similar com- plete renewal took place before the chalk was deposited. And in the southern parts of England the chalk is covered by other more recent strata, filled with shells and other marine animals, entirely different from all those which lived and died before. Identical Fossils in Rocks of the Same Age. Further investigation has demonstrated, that conclusions thus drawn from local researches apply with considerable accuracy in other situations, even at great distances, where the same strata occur. A catalogue of the corals, crinoidal remains, products, spiriferse, terebratulae, orthoceratites, and trilobites, of the mountain limestone in Yorkshire, may be em- ployed for labelling the fossils collected from the same rock at Namur and Liege ; the lias of Whitby contains many of the same ammonites, and the same saurian skeletons as the contemporaneous beds at Lyme, and in Westphalia and Wirtemberg ; and the remark- able echini and belemnites of the English chalk accompany that rock through France and Poland to the shores of the Baltic. The same observations have been made on the other conchiferous strata of England. Each has been traced through the island, and its organic treasures have been explored at every point, and in this manner satisfactory proof has been collected, that along its whole course the fossils which it contains are almost entirely the same. The researches of foreign geologists have demonstrated the truth of this law for the greater portion of the European basin of strata. The figures and descriptions of the English fossils are referred to by the geologists of France, Switzerland, and Germany, and no doubt remains that each extended stratum is the repository of the animals inhabiting the sea at a certain period in the earth's formation, exactly as the earthy bed of the present sea now envelopes the remains of its present corals, shells, echini, and fishes. General Principle of Smith. The general principle, therefore, which regulates the distribution of organic remains in the earth may be thus expressed. They are associated according to the periods at which they existed, and they are enclosed in the rocks which were at those times deposited by the water. And as in ancient times, much more than at present, the animal remains over considerable breadths of the bed of the Northern Sea were nearly identical, strata of the same age contain generally the same fossils. Also, because the inhabitants of the ocean were, in the course of time, completely changed, the old races having been extinguished and new ones brought forward to occupy their places, strata of dif- ferent ages contain generally different fossils. SMITH'S LAW DESHAYES' INVESTIGATION. 69 These important propositions form the groundwork of the history of the stratified rocks, and must be ever present in the mind of the modern geologist. The honour of their discovery belongs to Mr. William Smith, an engineer of eminence, who, being employed in 1790 and the following years in surveying colleries, and planning and executing a canal in Somersetshire, established the English system of geology upon the following enunciation : " That the strata are laid upon one another in a certain definite order of succession or superposition ; may be traced in continuity on the surface of the earth ; and may be discriminated when of different ages, and identified when of the same age, by their embedded organic contents." Oradual Changes in the Races of Organic Being. By comparing a sufficient number of fossils from all the several strata with analogous living tribes, we discover that those fossils which more nearly re- semble the living kinds belong to the strata which were deposited at the least ancient period ; as for example, the crag shells of Nor- folk and Suffolk, the London clay shells of Hampshire and Highgate, which are all more recent than the chalk. In these situations we find the families, genera, and even species of shells so similar to recent kinds existing somewhere or other in the ocean, that though they are often very different from the pro- ductions of our neighbouring seas, we not the less perceive that they belong to a system very like that now established. On the other hand, those fossils which present the least resem- blance to their successors in the modern system of nature, belong to the older, and especially the oldest of all the conchiferous strata. It is in the silurian and carboniferous limestones that the singular brachiopodous bivalves, producta, spirifera, pentamerus, the remark- able genus orthoceras, the zigzag goniatites, the still but half ex- plained tribes of trilobites, the beautiful crinoidea, chain corals, and favosites, compose a zoological suite, altogether unlike what now exists, a strange and antique order of beings adapted to the primeval deep. If we estimate the relative periods which intervened between the deposition of any given rocks by the variety and thickness of marine strata which separate them, we shall find that in proportion to the distance of the strata from each other, in proportion to the differ- ence of their ages, is the difference of their zoological contents. Thus the fossils of the mountain limestone are more different from those of the lias than from those of the magnesian limestone. The lias fossils are wholly different from those in the chalk, but partially similar to those in the Bath oolites. M. Deshayes* Results. The principle that the difference of the forms of ancient organic life from those of existing nature is directly proportionate to the difference of the epochs of their existence, was 70 DISTEIBUTION OF OEGANIC BEMAINS. put to a severe and curious test by one of the best conchologists of France, M. Deshayes. Passing over the primary and secondary rocks, in which no plant or animal has yet been found identical with a living species,* he analyzed the tertiary fossils according to their relative antiquity, and obtained the remarkable result, that the lowest and oldest of the tertiary strata contain three and a quarter per cent, of species identical with living types ; that a second and less ancient group of these strata holds eighteen per cent, of such analogues ; a third more recent group, forty -nine per cent. ; and the most recent of all these deposits contains little else than modern species. "When we recollect that all these strata are of a date probably anterior to the creation of man and the present races of quadrupeds, the results of M. Deshayes' investigation must be considered as highly valuable data towards forming a just notion of the great antiquity of the stratified rocks, the long periods passed through in their production, and in the accompanying changes of organic life, the gradual nature of these changes, and the correspondence of the general system of nature, at all epochs, even amidst the greatest particular diversity. Characteristic Fossils. Some fossils appear to have been in exis- tence only during the deposit of one particular group of strata, as, for example, certain products, spiriferse, trilobites, in the mountain limestone ; axinus obscurus, in the magnesian limestone ; am- monites Bucklandi, gryphaea incurva, in the lias ; ammonites calloviensis in the Kelloway rock ; hamites of many kinds in the Gault ; ananchytes, spatangi, belemnites mucronatus, in the chalk ; rostellaria macroptera in the London clay ; fusus contrarius in the crag. These are said to be " characteristic" fossils of the strata, and, in general, very great importance is justly attached to their recogni- tion ; but no geologist should permit himself to trust to them ex- clusively, for they are not always and invariably present, and he may be often called upon to fix the date of a rock by the help of other witnesses. Many fossils are found in more than one rock, and the number of these will probably be much increased by further inquiry. Thus, in the south of England, plagiostoma giganteum occurs in the lias and inferior oolite, terebratula intermedia belongs to the great oolite and cornbrash, pecten lens is found in the cornbrash, Kelloway, and coralline oolite, astacus rostratus and spatangus ovalis range through the Kelloway rock, calcareous grit and coralline oolite of Yorkshire ; and mya literata appears in nearly the whole range of con- chiferous strata from the marlstone to the coralline oolite inclusive. These facts entirely overthrow the notion favoured by some geolo- gists, that each rock contains the relics of a distinct creation of animals. They prove, on the contrary, that the changes were not * Terebratula striatula, fossil in the chalk, has teen thought to be identical with the recent shell, T. caput serpentis. GEADATIONS OE DEPOSITS AND FOSSILS, 71 sudden but gradual ; and suggest the hope that hereafter, when the laws of the distribution and transference of the existing marine races shall be better understood, and the history of the fossil species more complete, the phenomenon may be satisfactorily explained in accor- dance with the recognized laws of nature, " constant in her ceaseless change." Gradations of Deposits and of Fossils Coincident. It is generally observed that where the series of strata is complete, they are softened as it were one into another by an admixture or alternation of ingre- dients. Thus, for instance, in Somersetshire, the new red marl and lower lias clays are sometimes softened into one another ; and in Yorkshire, the Kelloway rock, Oxford clay, lower calcareous grit, coralline oolite, upper calcareous grit, and Kimmeridge clay are so blended at their junctions, as to render it difficult to draw any hard line of separation. In such cases it commonly happens that several fossils of the lower rock are continued into the next above, and thus the zoological change is as gradual as the mineralogical one. On the contrary, when two strata are separated by a hard and decided line, as, for instance, the coralline oolite and Kimmeridge clay near Oxford, we shall generally be justified in suspecting that the lower stratum is imperfect, in consequence of the removal of its upper beds before the next stratum covered it. In this case the zoological con- trast between the two rocks is as decided as the mineralogical one, and keeping in view the Linnsean adage, natura non facit saltus, we should be on the look-out for some intermediate beds in other places. Such are described near Weymouth, by Sedgwick ; and in Yorkshire, have been named the upper calcareous grit. The chalk in England contrasts so entirely with the tertiary for- mations above, that we naturally expect to find in some other coun- try beds of intermediate characters to connect them. These are found at Maestricht, where a sub-cretaceous, granular rock, interme- diate in composition between chalk and calcaire grossier, contains many fossils of the chalk, and several which strongly resemble those of the tertiary group. Probably more complete researches on this point will make known a greater number of such intermediate strata, soften the contrasts between contiguous rocks, and fill up all the blanks in the harmo- nious system of gradually changing marine deposits, characterized by corresponding transformations of marine exuviae. Terrestrial Animals and Plants. The remains of terrestrial animals embosomed in the earth are very few, and those of plants bear so inconsiderable a proportion to the flora of the present age of the world, as to give us much less information concerning the ancient, state of the land, than the marine exuviaB afl'ord of the former con- dition of the sea. 72 PEIMAEY BOOKS. But as far as they go they confirm in the most satisfactory man- ner the conclusions drawn from the consideration of marine remains, of the succession of systems of organic nature. The plants which sometimes alternate with, and which overlie in immense variety and abundance the mountain limestone, are a group eminently distin- guishable from those which belong to the oolitic coal beds. In the former deposit, lepidodendra, sigillarise, stigmariae ; in the latter, cycadeae and zamiae ; and the plants of the strata above the chalk, are still of a different type. It would thus appear that the same systems of calcareous rocks which contain the most remarkably different suites of zoological remains, likewise enclose in the alternating beds of sandstone and shale plants equally distinct. As amongst the marine, so amongst the terrestrial remains, those most decidedly unlike the modern productions of nature belong to the most ancient deposits. In the intermediate portion of strata the discrepancy diminishes, and in the most recent rocks, the plants strongly assimilate themselves to the genera and even species which now cover the surface. We might here examine the conditions of the land and sea as to climate during the several epochs of organic existence, a subject of the greatest curiosity and interest, and for which an immense mass of materials is already collected ; but this investigation requires the statement of details which cannot be here with propriety introduced. We must, therefore, postpone the discussion till we come to treat of the strata and their contents in the order of their successive depo- sition. We shall then also enter into the history of the fresh water for- mations which locally diversify the great mass of marine deposits, and contribute to elucidate the character of the ancient land and streams. CHAPTEE IV. PEIMAET EO C KS . Granitic Basis of the Crust of the Earth. Oeneral Basis of Plutonic Rocks Having now stated general principles, useful alike to the geologist who investigates in the field, and to the student who reads in his closet, we proceed to describe the successive systems of aqueous deposits, beginning with the lowest of all, viz., those which rest upon granite and other crystallized and PLUTONIC BOOKS. 73 unstratified rocks. That there is such a basis of crystallized rocks beneath all the strata, in all countries, cutting off and limiting our observations, and hiding whatever wonders are concealed below, is now universally admitted. The subjacent position of granite is so fully established by observation, that even when portions of it are clearly seen to be laid upon stratified rocks, no doubt is entertained of its having been in every case ejected from its true source below all the strata. But the same observations, which so clearly establish this important law, as certainly overthrow the dogma, once held incontrovertible, that granite is always the oldest of known rocks. They prove to a certainty that granite is of all ages, or, more pro- perly speaking, that its production has really no relation of age to the deposition of any particular set of aqueous strata ; but that it has been produced by agencies entirely independent of them, and only locally, and in one sense accidentally, brought into juxtaposition with them. This interesting discovery, from which we learn that the production of granite below the stratified rocks has been con- tinued, perhaps without intermission, during the whole period of the accumulation of the strata, has greatly changed and improved our conceptions of the whole system of geology, and is probably destined to clear still more the horizon of this science. But we must be care- ful not to be allured by this new light too far from those inferences concerning the age of granite which it so properly qualifies. It does not follow, because some granite is more recent than chalk, that therefore all granite is more recent than gneiss and mica slate. It does not follow, because when in contact with granite veins, gneiss may sometimes assume perhaps even more than even its usual grani- toid aspect, that therefore granite is merely fused gneiss, that gneiss and slate are incipient granite, and that common sandstone may in time become gneiss. But it does follow, as a matter of high probability, independent of further observation, that because granite has been formed at several periods during the deposition of strata, by agencies excited far beneath and independent of them ; and because, in some instances fragments, and universally what seem to be the disintegrated ingre- dients of granite, lie in the oldest strata, that the production of this rock was in progress before any of the strata were deposited ; whether those strata now rest upon that old granite or have been forced by subsequent convulsions into contact with newer portions of the same kind of rock. Whatever theory on the original formation of granite we choose to adopt, it must be allowed that the igneous action to which it owes its birth both preceded and succeeded the aqueous operations, which accumulated the lowest strata now observable. 74 PRIMABY STRATA. Primary Strata. This being admitted, two points of inquiry suggest themselves with respect to the age of the strata which have been called primary. First, are those strata really the altered deposits of one long period of aqueous action prior to all the secondary and tertiary strata, or have many repetitions of igneous action primarized, to use Mr. Conybeare's remarkable expression, strata of all ages, secondary and tertiary, which happened to be the lowest at the points of action ? Secondly, may we believe, as the title of primary seems to imply, that these are the oldest of all the strata, the first that were laid by water upon the consolidated igneous crust of the globe ? That these questions should be put at ah 1 will probably appear very surprising to those who have drawn all their notions on the subject from books of some date, without attending to the rapid progress of geological opinions. Primary Strata not to be known only by Mineral Characters, but by their Position. On the first question we may remark, that it must be allowed that subterranean heat, operating chiefly by the ejection of melted Plutonic rocks, has transformed to a certain degree and limited extent, strata of all ages which were exposed to this action, and thus made the lias shale of Savoy, for example, approximate to the character of clay slate. In such cases, there can be no objection, we conceive, on the part of any geologist to apply the same term to this change of the rock, which we may think fit to employ when treating of the analogous change presumed upon very good grounds to have affected in more ancient times the strata called primary. We may, therefore, adopt at once Lyell's term of metamorphic, and designate by it all those parts of certain aqueous strata which have been transformed in structure or appearance by subterranean heat applied since their deposition. All strata then may become metamorphic under given conditions, and may assume, locally, some of those appearances which belong, perhaps universally, to the primary strata ; but are we, therefore, to deny the antiquity of these latter ? or to group all such metamorphic strata together as of indefinite age, and merely characterized by proximity to igneous rocks ? Surely nothing could be more in contradiction with the principle of classi- fication of strata, the relative antiquity of their deposition. We cannot, therefore, agree to the term hypogene of Lyell as applied both to granite and the lowest of the strata usually called primary. When applied to granite it is synonymous with, and may perhaps be preferred to Plutonic ; when applied to stratified rocks, its mean- ing is better conveyed by the term metamorphic, which we shall apply to those portions of all strata, without regard to their age, which are in the altered condition implied. METAMOEPHIC STBATA. 75 The true conclusion on the subject of the first inquiry then ap- pears to be, that we are not to assume strata to be of the primary age merely because they appear to have undergone certain changes, analogous to those which gneiss or clay slate have sustained ; but we must determine their age by the very same methods as we use in any other case of stratified rocks, viz., by examination of their position relatively to other strata, their organic remains, and their original mineral composition and structure. Examined in this way, there can be no doubt, we conceive, that the use of the term primary, as applied to the extensive series of gneiss and mica slate rocks generally, defining them as a certain mass of strata anterior to most of the palaeozoic and all the secondary and tertiary rocks, is perfectly correct, because in all countries where these rocks occur together, the inferiority of their position is well proved ; and they have those general analogies of original composition, and those relations to organic remains, which would be satisfactory evidence in every other case. Those who reject the term primary, and yet retain the use of secondary and tertiary, have constructed a series wanting its first term. Are Primary Strata the Earliest Deposits from Water ? The answer to the second inquiry cannot, perhaps, in the present state of know- ledge on the subject, be given with the confidence of assured impar- tiality. It certainly does not follow that because gneiss, for ex- ample, is generally allowed to be the lowest of the stratified groups which we can trace, that there may not be other strata of a totally different nature below it, partially or wholly concealed by Plutonic rocks ; still less is it evident that such strata may not have existed, and been subsequently absorbed into the general mass of igneous rocks below. Geologists of eminence appear to think that granite itself is a derivative igneous, from an earlier stratified rock ; and that as gneiss is certainly in some respects to be compared to partially fused sandstone, so it may be supposed that while, above, the mass of strata was augmented by additions from water, it was diminished, below, by the transforming action of heat. Strange as this notion may appear, we certainly are not at present in possession of facts sufficient to wholly disprove it. But neither are there any facts to raise it above the rank of a general speculation grounded on particular and local alterations of stratified rocks. It can- not, therefore, be admitted for want of sufficient evidence, and, perhaps, the following considerations will justify us in rejecting it. The oldest of the primary strata undoubtedly differ from those of later date by the more decided appearances which they present of being derived from the disintegration of pre-existent granitic rocks. The character of the organic remains in the palaeozoic portion of the primary strata is in general so remarkably contrasted with those which at present 76 PEIMABY STRATA. exist, that, joined to the diminution and final extinction of their numbers as we descend in the series, and the almost perfect identity of their characters over immense geographical areas, we seem really to behold in them the first terms of organization, the earliest records of the establishment of life upon the consolidated crust which over- spread the fused matter within the globe. Conclusions Admitted. However, without plunging further into premature speculations of this nature, we shall content ourselves with the admitted conclusions. 1. That there is a sequence of age to be traced through all the stratified rocks, which may, therefore, be very justly grouped in any suitable number of successive divisions, as primary, secondary, and tertiary, and that these terms, if convenient, are not improper. 2. That the series of stratified deposits, whether we know their first terms or not, were laid upon a general basis or floor of Plutonic rocks. 3. That the term primitive, whether applied to igneous or to aqueous deposits, must be abandoned, as affirming what is not, and perhaps cannot be proved. 4. The alterations of strata, whether by general igneous agency, or by the local contact of melted rocks, being an effect wholly inde- pendent, both as to cause and to period, of the deposition of strata, must be treated in connection with the other effects of subterranean heat. Governed by these considerations, the descriptions in the succeed- ing part of the treatise will follow the order of time which is marked by the successively deposited strata. Exceptions to this rule will occasionally occur where it is neces- sary to notice the changes produced by igneous agency in the con- dition of the bed of the sea, and other circumstances which influ- enced the character and extent of the aqueous deposits. In the following description of strata, we shall retain the general titles of Primary, Secondary, and Tertiary Strata, combining with them a parallel set of names Hypozoic, Palaeozoic, Mesozoic, and Cainozoic strata and divide them into several systems and forma- tions according to certain properties, or in agreement with their elective associations. The reasons which have determined the mode of arrangement in each case will appear in the history of the several systems.* * The word " System," which was employed throughout the first edition of this work, 1832, et sea ann. has become the favourite mode of expression for the collective assemblages of strata which have or are assumed to have the requisite synthetic characters for " standing together," MOUNTAIN BANGKES. 77 Eange of the Primary Strata. Smdy of Mountains. At all periods in the history of geology, per- sons of enlarged views have passed over the limited areas of particu- lar islands and kingdoms, and have sought to connect the results of their local inquiries with those drawn from similar researches else- where. In this point of view the long chains and insulated groups of mountains become of the highest interest. Those peaks on which the snow rests for ever, whose rocks contain few or no vestiges of life, may be imagined to have stood up in ancient times above the level of the waters, dividing the primeval deep into seas very different from those which now branch off from the ocean. And though this supposition is probably inaccurate, though modern researches render it extremely credible, that, in fact, many of the mountain ranges, far from limiting the ancient sea, and altering the nature of its de- posits, were really raised out of its depths at periods comparatively recent, this does not diminish their geological importance. For if by means of this uplifting we are made acquainted with some of the materials which would otherwise have been concealed from the eye of philosophy, these mountain ranges must be studied as the basis of the whole system of geology. They form, so to speak, the skeleton of the earth, and are the marking features of its topography ; their insulated groups charac- terize kingdoms, their long connected chains divide the races of man- kind, and define the geographical limits of the distribution of land animals. To the geologist they have become still more interesting, in consequence of a remarkable general law of their physical struc- ture. For in all climates of the earth, under every conceivable variation of external circumstances, the principal ranges of moun- tains are everywhere composed of, or at least contain in their axes or nuclei, similar rocks, and those originally the lowest, and in part at least the oldest, with which we are acquainted. By what violence from below they have been uplifted to their present heights, so as to break through and rise from beneath the strata which were super- imposed upon them in succession, is a capital question in geology. These rocks are the primary strata of gneiss, mica schist, slate, and their many associated rocks, the deposits of water, resting upon and often pierced by granite and other crystallized compounds from fusion. An outline of the mountain groups and chains which diver- sify the face of our planet, seems, therefore, the best foundation for a systematic view of the strata which rest against these rocky barriers. Relations of Mountain Ranges and Groups. It has long been the fashion to attempt to establish certain geometrical relations among 78 BANGE OF THE PBIMAEY STRATA. the chains of mountains, to refer them to particular parallels and predominant directions, but this labour, unconnected with geological researches, seems to have been very fruitless. Perhaps it would be more correct to say the essence of the geographical relations amongst mountains is irregularity. For though we speak of long-continued chains and belts of mountains, it is very certain, in fact, that to be assembled in groups is the real character of mountain association, and that the chains and belts are nothing but approximated groups. A geological map is in this respect a most valuable instructor ; from it we see that, instead of the plains being insulated among the mountains, instead of the upper strata appearing in small contracted patches, like oases in a desert, they spread wide, and flow round the bases of the mountains., as the ocean encircles the islands and con- tinents. Among the few general remarks on this subject, we may observe that the most insulated and many of the loftiest emi- nences on the surface of the earth are the volcanic summits ; the most connected ranges of uniformly high ground are formed by the secondary limestones. Finally, that the general outline of countries is much influenced by the direction of their interior mountains. European Basin. The Scandinavian chain, commencing at the North Cape, runs parallel to the coast of Norway, and gives off branches to the east, which pass round the Gulf of Bothnia. The line of the Scandinavian chain may be imagined to cross the sea to Zetland, and from thence to proceed by the Hebridian Isles and the north-western half of Scotland to Ireland, where it is much broken into separate groups in the north, south-east, and south-west of the island. The Isle of Man, the south-western part of Scotland, the Cumbrian group, the broken mountains of Wales, and those of Devon and Cornwall, are so many separate protuberances of the in- terior rocks of the earth, which, with Bretagne and the north of Spain, compose the interrupted western border of Europe. The Pyrenees, ranging to the east, may be considered as carrying on the primary range toward the Alps, which hold so long a course from the shores of the Mediterranean in a winding direction to the Danube, and seem to prolong themselves in the inferior ridges of the Carpathians toward the Black Sea and the Caucasus. If, now, we consider Caucasus as continuing the Alpine line round the Caspian Sea to the lofty Paropamisan and Graur mountains, and from thence turn northward along the summit of drainage, including the Sea of Azof, we come to the Uralian chain, which leads us to Nova Zembla, and thus we find nearly all Europe, and a considerable tract in Asia, enclosed within this irregular circle of primary mountain groups ; and it may often hereafter be convenient to speak of this space as the European Basin. It is within this region that the greatest variety of stratification has been observed. ASIATIC BASINS. 79 Within this area are the primary elevations of the centre of France, the Ardennes, the Vosges, the Black Forest, the Thuringerwald, the Harz, and the Bohemian Circle ; south of it are the Sierras of the Spanish peninsula, Corsica, Sardinia, the Apennines, the Dalmatian ridges, and the mountains of Greece and Mount Haemus. Asiatic Basins. Another basin of about equal extent, but more perfectly denned in its boundaries, and more uniform in its interior composition, is that great Siberian tract which lies to the east of the Uralian, arid to the north of the Altaian, Yablonoy, Stanovoy, and Kamschatdale mountains. The vast empire of China and Tartary lying to the south of the Siberian basin, and to the north of the Indian empires, may be considered as a third great but divided basin between the Himalayan and Altaian heights. The peninsular Indian regions, with their islands stretching to- ward New Holland, Persia, and Arabia, derive their features from considerable primary mountains directed more parallel to the circles of longitude. Africa. The mountains of Africa are long, unconnected ranges. The southern part of Africa is similarly denned by the long ridges of mountains which run from Cape Guardafui in the east, and above the sources of the Congo on the west, to converge about the Cape of Good Hope ; while the greatest breadth of this pen- insulated continent, from Cape Yerde to Cape Guardafui, is coin- cident with the high mountains of Kong, Donga, and Southern Abyssinia, and the north-western projection is caused by the ele- vated Atlas. Principal Line of Mountains. The interrupted system of primary mountains which extends from the Pyrenees to Behring's Straits may be supposed to continue in the long and magnificent Cordillera parallel to the whole western coasts of America, while the north- eastern shore is parallel to the Alleghany and its northern connec- tions, and between these and the western Cordillera, the vast basin of the Mississippi pours its waters into the Gulf of Mexico. The eastern projections of the coast of South America, which t in a cer- tain degree correspond to those of Africa, are owing to lateral ex- tensions from.the great western Cordillera. Though the above enumeration and classification of mountains be extremely imperfect and subject to many objections, it answers the purpose intended, which was to show that the leading features of our continents, their geographical extent and connections, are depen- dent on the lines of mountainous land, and as these are for the most part constituted of the lowest and oldest stratified rocks, resting on, and uplifted with, granitic compounds, it generally happens, as Mitchell foresaw, that in every country the secondary strata are arranged with reference to the lines of mountains. 80 HTPOZOIC STRATA. Elie de Beaumont's Theory An entirely new kind of interest has lately been given to this subject in consequence of the researches of an eminent foreign geologist . Elie de Beaumont, from considerations of some observed accordances between the direction of mountain chains and the geological era of their uplifting, has advanced the hypothesis that these two circumstances are always mutually depen- dent ; and, in consequence, supposes that all ranges of mountains which were uplifted at the same period are parallel to one and the same great circle on the sphere. This is not the place to examine this curious question as fully as it deserves, and we shall, therefore, only mention some of the cases in which this ingenious geologist supposes that the truth of his doctrine may be recognized. If a great circle be conceived to pass round the earth through Natches and the mouth of the Persian Gulf, and the directions of mountain chains be compared with it, it will appear that the Pyre- nees, part of the Apennines, the Dalmatian and Croatian ranges, and part of the Carpathians, are parallel to it. Now, in accordance with some researches of geologists, M. de Beaumont supposes that all these mountain -chains were thrown up at the same geological epoch. Nearly parallel to the same circle are the Alleghanies of North America, the Gauts of India, and the Paropamisan heights; but in all cases very much information is required before we can be asked to admit that distant mountains may have been thrown up at the same epoch. Another circle may be traced on the sphere parallel to the Alps, from the Valais to Styria, and to this system we may refer the Atlas, the Caucasus, the Balkan, the Himalaya, &c. ; and, according to the hypothesis of M. de Beaumont, these must have been all raised at so late a period as since the deposit of the tertiary strata. This subject will again attract our attention. CHAPTER V. HTPO ZOIC STEAT A. These strata, which have the aspect of being derived from decom- posed granitic rocks, with several subordinate and associated strata all devoid of organic remains, constitute, according to the concurring testimony of geological observers, the lowest group of the whole series of Neptunian deposits. From the effects of heat upon these rocks, their natural analogy to granite is sometimes so much height- ened, as to cause some uncertainty in distinguishing between them. FOEMATION OP PErtfCIPAL EOCKS. 81 The rocks of this whole series might without impropriety be termed granitoid strata. Principal Rocks. These consist principally of the two following rocks : Gneiss, a rock composed of the same mineral ingredients as granite, but laminated and stratified ; Mica schist, composed generally of quartz and mica, in alternate layers. With these are associated, and often intermixed, Quartz rock, generally appearing like a semi-crystalline or imper- fectly granular mass of quartz, variously modified by small inter- spersed quantities of mica, felspar, &c., sometimes more compact, and resembling the quartz of veins, in other examples, mixed with clay slate. Crystallized limestone, mostly granular. Serpentine, a magnesian rock generally distinguishable by its soft- ness, smoothness, and bright mottled colours. Steatite, a still softer and smoother rock than serpentine, generally of whiter colour. Potstone, a soft, often grey or greenish magnesian rock. Hornblende schist, a laminated rock of hornblende, variously modi- fied by felspar, mica, and chlorite, generally in alternate laminae. Chlorite schist, a rock almost precisely similar to mica schist, with the exception of the difference between chlorite and mica. It is subject to the same contortions as mica schist, and passes like it by insensible gradations to gneiss and clay slate. Talc schist, mentioned by MacCulloch, is another of the fissile rocks which differ from mica schist only by the substitution of one mine- ral for another. It is rare. With respect to the order in which they succeed one another, nothing very definite can be advanced. The greater number of ob- servations concur in assigning to gneiss the lowest place in the system, a conclusion supported by its evident analogy to granite, and in the same general way we may, perhaps, place quartz rock and chlorite schist in the upper part of this system, and next to the clay slate, with which, indeed, they are often associated. Limestone and serpentine are so irregular and peculiar in their occurrence, that though, perhaps, their era is more definite than that of any other of these rocks, they can scarcely be employed to mark a geological date. In some district or other, nearly all these ancient rocks alter- nate with one another so variously and unequally, that what would be called the oldest rock in one region, may be the youngest in another, and, therefore, it is no wonder if the attempts which have been made to divide the gneiss and mica schist system into several distinct formations have wholly failed. It is not till zoological evi- 82 HYPOZOIC STBATA. dence is brought to bear on the subject that we are able to demon- strate completely the relative age of strata, by distinguishing differ- ent deposits and different ages of the same kind of rock. Gneiss, its Origin. That the materials of the mechanically aggre- gated gneiss rocks, of the whole series of hypozoic strata, in fact, except the calcareous rocks, are derived from the disintegration of more ancient granite and other crystallized compounds, is an opinion which is strongly impressed upon every geologist while examining the composition of gneiss. The ingredients of gneiss and granite are the same, quartz, felspar, and mica ; they are mixed with the like accidents and permutations, and occasional admixture of other minerals, and are subject in both to the same extreme variation of size. But these rocks differ in the most essential point of view under which they can be compared, viz., the mode of arrangement among their constituent masses. The ingredients of granite are so connected together by contemporaneous, or nearly contemporaneous crystallization, that one substance pene- trates and is united into another, and we are compelled to conclude that they were accumulated together not in distinct pieces ready formed, but that they actually never had a separate existence as solids until their different properties were developed by crystalliza- tion from a fused mass. On the contrary, gneiss well characterized suggests almost always, by some degree of imperfection of the edges and angles of the quartz and felspar, and much more decidedly by the laminar arrangement of the mica, and consequent minute stratification of the rock, that its materials, ready made and crystallized, were brought together and arranged by some mechanical agent, principally influenced by gravitation, in fact by water. Could any doubt remain on this sub- ject after a sufficient examination of gneiss strata, in all their grada- dations from a rock resembling granite to a fine grained fissile mass, hardly distinguishable from clay slate, it would surely be at once removed by comparing them with a suite of sandstones, many of which, like gneiss, are composed of granitic detritus, and strongly allied to it in structure, but not having undergone metamorphosis, show clearly that they were aggregated by water. In a great majority of instances, gneiss rocks immediately follow granite ; being then composed of the materials of that rock which had suffered the least degree of waste and abrasion, it is no wonder that on several occasions it should strongly resemble its parent. And if we allow, what may probably be true, that the heat of the granitic nucleus was then sufficient in some places materially to affect the consolidation of the strata on the bed of the sea, we shall perceive another cause why the most ancient mechanical strata ap- proach in character to the Plutonic rocks. STEATIFICATION OF GNEISS. 83 Though the disintegrated materials of granite compose almost universally the substance of gneiss, fragments of granite are most rarely discovered in it.* This circumstance, combined with its numerous laminse and crystalline aspect, seems to indicate that the aggregation of gneiss happened without any great degree of turbu- lence or lateral motion in the water. It may, perhaps, lead us to suppose that in those early periods the fluctuating temperature of the bed of the sea contributed sometimes to accelerate the aqueous decomposition of the granite, and afterwards at intervals to harden its stratified materials into gneiss. stratification of Oneiss. Gneiss beds are of extremely various thick- ness, and the laminse of which they consist are subject to such ex- traordinary curvatures, that it is often very difficult to trace them. Where other rocks alternate with gneiss, as hornblende, slate, quartz rock, limestone, or mica slate, the stratification is rendered very evident, but otherwise the beds are less regular, and are often discontinuous, as in micaceous sandstones and in argillaceous slates. The contortions of the laminse of gneiss are observed to be most numerous and surprising, where, as frequently happens, veins of granite, quartz, or felspar divide this rock. These veins cross the laminae at various angles, and generally cause some peculiar twists along their sides ; they not unfrequently insinuate themselves be- tween the laminse, and in this case, when thick and extensive, may be mistaken for alternating strata. It is probable that many cases of supposed alternation between gneiss and granite may be thus ex- plained, and that in other cases the rock called granite may be really a coarsely granular gneiss, whose particles have been very little moved by water, or unusually affected by subsequent application of heat. Mineral^. Gneiss being one of the most extensive stratified rocks, is a rich repository of minerals, both in the new and the old world. Garnets frequently, zircon, beryl, disthene, epidote, tourmaline, rutile, oxide of tin, oxide of iron, sulphuret of molybdena, more rarely, are disseminated in its laminse. The veins of quartz, cal- careous spar, carbonate of iron, and sulphate of barytes, which divide it, contain the sulphurets of lead, copper, and zinc, native silver, tin, &c. in Sweden, Germany, and Brazil ; and many other minerals occur in the calcareous strata which alternate with, or are enveloped by, the strata of gneiss. Rocks Associated with Gneiss. Gneiss alternates with granite in the Riesengebirge and in Quito, and in some cases graduates into the character of granite, as on the southern declivity of the Titlis * MacCulloch says that in certain varieties of mica schist, fragments of granite, of quartz rock, and of limestone, are embedded in it. Perhaps he may not always have been careful to avoid admitting conglomerates among mica schist and gneiss. 84 HTPOZOIO STKATA. and Jungfrau (the age of this gneiss, however, may be more recent) ; more frequently it exchanges beds with mica schist, hornblende schist, and granular limestone and clay slate. These rocks are some- times in such small quantity as merely to mark lines of division in the mass of gneiss, but at other times they swell out to great thick- ness. The limestone beds in particular are remarkably local and irregular in their occurrence, and instead of extending, like the more recent calcareous strata, through large tracts of country, appear in the form of large lenticular masses, enveloped on every side by the predominant rocks of gneiss. The term subordinate, on a great scale, is not improperly applied to these lenticular rocks, though in local geology their occasional great extent and comparative regularity may entitle them to be classed under an independent title. Thus Charpentier arranges the granular limestone of the Pyrenees. By the substitution of hornblende for mica, gneiss gradually changes to hornblende schist ; the loss of its felspar approximates it to mica schist, the diminution of its mica produces the resemblance of quartz rock. A finely granular slate, with more evidence than usually appears of watery friction among the particles, almost trans- forms gneiss to sandstone (Dalnacardoch) ; a more minute admixture of its ingredients, with a predominance of chlorite, gives it the aspect of argillaceous slate. In all these cases great caution is required, and its geological relations should always be consulted before de- ciding on the name of this Protean rock. These gradations happen most frequently at the junctions and alternations of the several rocks. mica Schist, its Origin Mica schist, like gneiss, appears to have derived its ingredients from the destruction of granitic rocks ; but it contains but little felspar. May we conjecture that a variety of this mineral, easily acted on by ordinary agents, was itself de- composed during the disintegration of the granite, and mostly dis- solved, leaving the quartz and the mica to be arranged by the water in the alternate layers which render this rock so remarkable ? The lamination of this rock is subject to much unevenness, in con- sequence of the irregular size and arrangement of the pieces of quartz, and the undulations thus occasioned on the micaceous surfaces, are often further modified by interspersed garnets, for these appear to have pushed aside the other ingredients. Besides this minute ine- quality, the laminae of mica slate are liable to the same contortions and curvatures as those of gneiss ; the same difficulty often occurs in tracing its beds, similar and very numerous veins of quartz tra- verse and mingle with its layers, and when in contact with granite it is locally penetrated by similar granite veins. Small cavities lined with crystals appear among the most contorted parts. The sketches presented below, (figs. 19, 20,) were taken with care DISSEMINATION OF MIKEKALS. 85 from the mica schist near the anticlinal axis of these beds, which crosses the upper part of Loch Lomond. On a great scale, the lami- nations of gneiss and mica schist are sufficiently parallel to give the idea of disturbed surfaces of deposition ; on a small scale, by close examination, innumerable centres of local forces, producing minute, recurring, and anastomozing curvatures appear. These minute flex- uosities are clearly due, not to general or external pressure of the whole mass, but to the mechanical displacements effected in the mass by the generation of new minerals (as garnet), the aggregation of others (as quartz, or felspar, or both). Thus the mica and chlorite which generally meet the surfaces of lamination, appear to have been shouldered about, without being fused, twisted in their struc- tural planes, and subject to that curious minute folding which is often observed as one of the effects of cleavage structure in delicate and pliable shells, in slates, for which the term " creep" was used by the author in 1843. See small figure 20 a. Minerals. Various minerals are similarly disseminated through it, as garnet, emerald, beryl, disthene, tourmaline, fel- spar, epidote, horn- blende, colum- bium, molybdena, rutile, oxide of tin, wolfram, oxide of iron, grey cobalt, native gold. Its metallic veins are of the same na- ture as those in gneiss : it alternates in the same way with quartz rock and the older slates, and encloses similar deposits of limestones. It seems, therefore, almost su- perfluous to say, that the line of rigid dis- tinction between the mica schist and gneiss can only be drawn in the closet. Yet, in fact, on a great scale, the two rocks retain their typical characters over large tracts of country, and must be considered apart. 86 HTPOZOIC STRATA. Quartz Rock. Quartz rock, in the greater number of instances, seems a more recent deposit than mica schist and gneiss, though, indeed, by an easy change of its composition, it becomes nearly iden- tical with them. This circumstance, combined with the internal evidence of texture, seems to decide the question of the origin of quartz rock, and to prove that, however altered by subsequent igne- ous action, it is originally a Neptunian and mechanical deposit. The degree of compactness which it exhibits varies through a large range, in some cases approaching the loose granular character of sandstone,* in others the density of the quartz of veins. In this latter case it seems that the mass is composed of fragments so firmly united as to suggest the idea of their having been soldered or fused together since their deposition from water. Perhaps, also, in some cases, what has been considered as quartz rock may be really an expanded or over- lying vein. Minerals. In South America, this rock is the repository of many rich ores and metals. Native gold is found in Brazil in a stratified rock of quartz, and micaceous iron ore, which is suspected by M. Eschwege to be the original repositoiy of diamonds, and appears to be intimately related to quartz rock. The flexible quartz of the same country is a granular rock with drusy cavities containing topaz and am ethyst . (Brongniart .) Crystalline Limestone, its Origin. Crystalline limestone is in gene- ral observed to be stratified, frequently to alternate with gneiss and mica schist, and sometimes to retain argillaceous partings ; it is therefore a Neptunian deposit. Its frequent high state of granular or saccharoid crystallization may perhaps be due to changes operated since its deposition, and partly occasioned by the action of subter- ranean heat, of course more sensible in the lower than in the upper calcareous deposits. It is difficult to imagine that such a rock could be formed by crystallization from water, often in laminae exceedingly thin and regular, and alternating with evidently mechanical deposits. That the calcareous matter of many rocks, at first precipitated in sedi- ment, has been since arranged in crystalline and concretionary masses, is certain. Thus the oolitic structure, thus the crystalline cement of the Lincolnshire oolites, has been occasioned. These effects, it is now known from artificial trials and from observations in nature, are more decisive when heat and pressure operate upon the particles. By this combination, the earthy sediment of chalk is condensed into crystalline limestone. * Some of the quartz rocks of Scotland and Anglesea have a conglomeriticc haracter. In Garveloch, Von Dechen noticed rounded masses of granite, quartz, and corneous limestone em- bedded in a basis of clay slate, passing to quartz or mica schist. Mr. Sharpe cautions us that some of the quartz rocks of MacCulloch are of later date. (Phil. Trans. 1 851.) CRYSTALLINE LIMESTONE. 87 The deposits of crystalline limestone, whether distinctly stratified or not, are in general detached and limited, and so entirely enve- loped in the strata of gneiss and mica slate, as to compose but a sub- ordinate member of those extended formations. This fact appears to indicate that in the earliest periods of Neptunian operations, the precipitation of calcareous matter was occasioned by agencies of a more local and limited nature than those which produced the broad strata of lias, oolite, and chalk. May we imagine that the accumulation of these nucular or lenti- cular masses was determined by local developments of subterranean heat, which, directly, by change of temperature, or by intermediate chemical agencies, might render the calcareous matter insoluble ? However we may seek to explain it, the fact is undoubted, that during the aggregation of the gneiss and mica slate systems, a large quantity of calcareous sediment was deposited, not in one uniformly extended stratum, but at scattered points, and in unequal quantity. And this irregularity of deposition continues to be observed in an inferior degree in the limestones of the lower palaeozoic system, which are often lenticular, but above this point, where the influence of the in- ternal heat must be supposed less intense and more equally diffused, the calcareous strata become at once more abundant, more regular, and more uniformly extensive. Minerals. Though primary limestone be, in fact, a simple rock, its aspect admits of many variations from the unequal admixture of other mineral substances. Of these the most frequent are mica, talc, and steatite, the latter of which often communicates a green or mottled colour to the whole rock. Crystals of augite (Tiree), gar- nets, and felspar (Col. de Bonhomme), occur in it in some places, and tremolite and argillaceous slate lie upon its laminae. It some- times assumes a brecciated character, as if composed of limestone fragments, and more rarely contains fragments of rocks of the gneiss and mica slate system. It is the fruitful source of statuary and architectural marble, con- tains a great variety of minerals, and is locally traversed by veins of quartz, felspar, and granite, and by veins of cobalt, galena, iron. Contains no Organic Remains. The limestone associated with the truly ancient gneiss and mica slate is destitute of organic remains. The gneiss and mica system may therefore be considered as hypozoic, or beneath the strata which contain reliquiae of palaeozoic life. But this distinction, when applied to such vast thicknesses of rock de- void of these remains, and variously alternating, acquires its just meaning only by adding other considerations which give it a theore- tical value. It has been said that if we suppose the crystalline lime- stones devoid of organic remains, to have derived their peculiar texture from changes subsequent to their deposition, under the influ- 88 HTPOZOIC STEATA. ence of subterraneous heat, it is possible that the absence of organic remains may be often a consequence of this change. This is pos- sible ; at the same time it will be shown by circumstances, hereafter to be mentioned concerning the slate system above, that there are strong grounds for believing that what we now call hypozoic strata were really formed when no organic life was manifested on the globe. To conclude this discussion, we may collect in a small compass the possible speculations of the origin of the gniess and mica schist. 1. That it is merely laminated or foliated granite, a rock of fusion ; the foliation being due to collection of the mica into certain lamina?, whether this be owing to an unexplained mode of segregation, or to internal motion in the mass during consolidation. This speculation fails, because of its being wholly inapplicable to the quartzitic, and chloritic, and talc schists, which certainly form a part of the gneiss- it e and micacite system. 2. That it is an originally semicrystalline, or confusedly crystalline deposit from thermic solution in water, a process by which many vein stones have been thought to be formed. This has been too little examined to allow of our pronouncing an absolute negative. Some- what in favour of it may be quoted, the minute and complicated con- tortions of the laminae analogous to what takes place in the deposits of steam boilers and apparently against it is the great prevalence of mica, which it is difficult to establish as originating from water. Mica, however, under the name of " peach," occurs in some of the Cornish veins, whose origin from mere dry heat is sometimes hard to conceive. 3. That the gneissic foliation is the original, or the remains of the original lamination imparted to the mass by the successive accumu- lation of its particles under water, and altered by subsequent action of heat. This heat is sufficient in some cases to modify the external texture, almost to obliterate the structure, and thus to reconvert the gneiss to granite, in other cases enough to solder the grains of quartz, felspar, and mica, and to generate new minerals of easier fusion as garnet and in other cases merely to impart a superior degree of coherence (as in quartzite). This view has the advantage of recon- ciling the diversity of the gneissic and schistose beds, with probable differences of mechanical origin and degrees of applied heat, and takes account of the general truth, that the foliation of the whole gneissite and micacite series is parallel to the great axis of move- ment, while the excessive abundance of minute flexures, the occur- rence of many cavities, and the frequency of intrusive quartz veins, are observed on and near to the summits of the arches of thelaminee. 4. That the irregular foliation of gneiss is in no degree original, but a case of superposed structure, produced in these granular rocks DISTRICTS OF GNEISS AND MICA SCHIST. 89 by the same general cause as that to which the regular cleavage of the fine grained clay slates is due ; that it is not stratification, due to successive aggregation of the parts, but a new crystalline arrange- ment of the particles. It appears a strong objection to this view, that the two phenomena here referred to one cause, have the oppo- site qualities of regularity and irregularity, on a small scale, while the conformity to one axis, which in this respect the formation of gneiss manifests with the cleavage of clay slate on a large scale, is unquestionably also shown by stratification. On the whole, we conclude in favour of the third hypothesis as most in harmony with the facts generally. Districts of Gneiss and Mica Schist. in England, &c. The extent of countries occupied by old gneiss and mica schist with their associated rocks is enormous ; and there are few districts of sufficient area where granite appears, without being followed by these deposits. But the order of their succession, and their relative thickness, are very uncertain. In some districts, gneiss, in others mica slate, in others quartz rock, make up the whole visible system, and are immediately succeeded by clay slates. There are even cases where the whole system is wanting, and large areas of granite are immediately invested by clay slates and limestones containing organic remains. In England, for example, gneiss and mica schist, and primary limestone, and quartz rocks, are almost unknown ; but in Ireland, and especially in Scotland, they are abun- dant, and include among them many gradations, chlorite slate, talc slate, hornblende slate, &c. In Cornwall and Wales the granitic rocks are almost universally succeeded by modifications of clay slate, Anglesea only exhibiting a quartzo-micaceous group below all the Cambrian slates ; and though in Cumberland the granite of the river Caldew is indeed covered by rocks, having the character of gneiss, mica schist, dark hornblende slate, (provincially called whintin.) and chiastolite slate, their area and thickness are inconsiderable, and the latter rock soon changes to clay slate. At a place called Martindale, at the eastern foot of Caldbeck Fells, is a fine-grained variety of gneiss in very thin, straight laminae. Granite veins are rarely known to divide any of the rocks of this region, except on a small scale between Skiddaw and Saddlebank. Gneiss occurs, sometimes exchanging its mica for hornblende, on the east flanks of the southern parts of the Mal- vern hills, much intermixed with trap. It may be regarded as older than the silurians of that region. The general order of succession among the older primary strata 90 DISTRICTS OF GNEISS AND MICA SCHIST. in Scotland may be represented in a diagram as in fig. 21, but it must be remembered that all the terms of the series are sel- dom coexistent in the same vicinity. Oneiss in Scotland. Gneiss is abundant in Scotland, par- ticularly in the northern and western parts, and being ex- ceedingly variable in compo- sition, is very often undis- tinguishable from mica schist, under which head apparently M. Bou has preferred to class many of its varieties. Gneiss constitutes almost the whole mass of lona, Tiree, Coll, Rona, and the Hebrides, and enters largely into the composition of the Zetland Isles, which are in some measure to be viewed as aprolongation of theHebridian group, as the Orkneys appear to be an extension of the eastern rocks of Caithness, Housa, Burra, Whalsay, Out Skerries, and Yell, and the western parts of Fetlar and Unst, and part of the mainland of Zet- land, are gneiss. The remainder of the mainland is principally mica slate, and the two rocks are partially separated from each other by an interrupted deposit of limestone. The gneiss is often porphyritic, as in Unst ; at Hagrasattervoe* it appears to contain masses of gra- nite as well as to be traversed by veins of syenite and talcose granite. Kaolin is derived from it in the mainland and in Fetlar. Gneiss exists likewise in the Orkneys around the granite of Stromness.f In the Hebrides, this rock changes often from the typical mixture of quartz, felspar, and mica, by the substitution of talcose minerals and hornblende for mica, by the omission of the quartz, and by the interl animation of argillaceous schist. Some varieties ace extremely slaty, and suffer rapid decomposition ; others approach nearer to granite, and present rude and naked surfaces and precipitous faces, with few brooks and little alluvium. The direction of the strata in the Hebrides is north-east and south-west, but the inclination is obscured by frequent contortions. These, in MacCulloch's opinion, are most frequent in the vicinity of the granitic veins which divide all the gneiss rocks, except those which are associated with clay slate. The drawing which he presents of the contorted laminae of gneiss and hornblende slate, in connection with ramifying granite veins, near Cape Wrath, seems to justify his views. The laminae of gneiss Hibbert, Edin. PhiL Jour. vol. ii. t Boud, Geologic de 1'Eccose. SCOTLAND. 91 are often peculiarly bent, or apparently dislocated along the line of the veins ; and sometimes masses of this rock are curiously enveloped in their substance. The veins are not often filled with granite of the ordinary kind, but with a compound rock, in which felspar highly predominates, so as to form in several places (Harris, South Uist, Rona, and Coll,) a real graphic granite, which in Coll contains garnets. Veins of quartz occasionally metalliferous, likewise traverse the gneiss of Coll and Tiree. Garnet, rose quartz, zircon, hornblende, epidote, fluor spar, iron pyrites, and sulphuret of molybdena, occur in the gneiss. Mica schist is not abundant in the Hebrides, but in Rona, Coll, and Tiree, it alternates universally with the gneiss. Gneiss occurs in many places, as round the granitic mountains of Braemar and Lachin y gair, at Kincardine in Ross-shire, and other points in the extreme north of Scotland ; but the most abundant and interesting deposit adjoins to the granite of Strontain. It forms the beautiful and picturesque region around Loch Sunart, which strongly resembles the Trosachs of Loch Katrine, being equally rich in wood, and remarkable for intricate confusion of rugged surface. The curvatures to which its laminae are here subject are very numerous and extraordinary ; veins of quartz, felspar, and granite are extremely common, garnets abound in it at certain points, and the metalliferous veins with carbonate of strontain, harmotome and re- markable calcareous spar are highly interesting. On the eastern side it is bounded by porphyritic masses, but in other directions appears to be overlaid by mica schist, to which its composition ap- proximates. Mica Schist in Scotland. But the principal part of the Highlands is occupied by the mica schist formation, whose strata range with more or less regularity north-east and south-west, notwithstanding the interruption to their continuity by the unstratih'ed rocks of the Brasmar mountains, and the groups of Ben Cruachan and Ben Nevis. The south-eastern limit of this vast deposit is the line of the foot of the Grampians from the Forth of Clyde to Stonehaven. Deposits of red sandstone, lias, and a carboniferous part of the oolites border the eastern coast from the River Spey to Duncansby Head, and extend through the Orkneys ; rocks of igneous origin, associated with the preceding, mostly occupy St. Kilda, Skye, Rum, Eigg, Mull, parts of Ardnamurchan and Morven. Within these limits, and with the exception of irregular masses of igneous rocks and of gneiss, the whole of the vast space belongs to the mica slate system, with its included quartz rocks, limestones, serpentines, potstones, its associated hornblende and talcose slates, and its overlying clay slates. 92 DISTRICTS OF GNEISS AND MICA SCHIST. The mountains of this system of rocks are formed into little groups separated by deep valleys and long lakes, and their bases being usually and thickly covered with birch, underwood, and sometimes with forests of oak, while their summits rise often more than 8000 feet above the lakes, the beauty of the scenery is admirable. Scenes, indeed, of a truly alpine character are very rare in Scotland, and, perhaps, nowhere occur except in the Cuchullin mountains of Skye, and the granite peaks of Arran ; but very grand and imposing effects are produced by the combination of narrow woody denies, precipitous slopes, and rocky crested summits. The general outline of the mountains is pyramidal, but this form, elegant at a distance, is broken on a near survey by fantastic projections, and bare cliffs, and by numerous channels, which after storms are changed into a multi- tude of waterfalls. The valleys destitute of lakes are usually wild and barren, and covered with scattered rocks. Several of the most remarkable valleys in the Highlands follow the ranges of the strata, as for example, the extraordinary valley of lakes which are united by the Caledonian Canal, whose highest sum- mit is but 90 feet above the sea, the valley of the Spey, Glen Tilt, Loch Tay, Loch Long, Loch Fyne, Loch Awe. M. Boue observes, that the longitudinal valleys are remarkably narrow, as if mere slits in the country, while the numerous transverse valleys are in general more widely expanded. One of the most interesting valleys in Scotland is Grlen Roy, ren- dered classical by MacCulloch's description in the Geological Trans- actions. Two narrow, parallel, contiguous terraces, perfectly level and continuous along the whole length of the glen, mark the higher part of its bordering slopes with a singular and most surprising character, the effect of ancient local operations of level water. It has been with probability conjectured that these lines are the traces of the ancient margin of the sea, left uninjured during a subsequent elevation of the whole country to the extent, perhaps, of 1500 feet. By the natives of these wild regions they have been traditionally supposed to be the works of man in the fabulous ages. As might be expected, the forms of the mountains, and especially the shape of their summits, is considerably characteristic of the kind of rock which constitutes them. Compare, for instance, the irregu- lar head and broken slopes of the Cobler and other mountains of mica slate, with the smoother sides and less angulated chloritic top of Ben Lomond, and the conical summits of quartz on Benan, Sche- hallion, and the Paps of Jura. Neither are the features of the valleys and waterfalls independent of the nature of the rocks which they traverse. The unequal hard- ness of mica slate, in particular, is often evident in the rapid streams, by singular hollows and pits in their course, and deep cavities under QTJAETZ BOCK TALCOSE SLATE. 93 the cascades. A waterfall near Loch Earn Head exhibits this fea- ture very remarkably. The most important point of view under which mica slate can be considered mineralogically, is the well-known variation and entire change of character to which it is subjected by alteration in the pro- portions and permutation in the nature of its ingredients. It can- not be thought surprising that a rock, constituted probably of the detritus of many granitic aggregates, should be extremely various in its composition. M. Boue is of opinion that we may observe on a great scale these variations to be dependent on the general prin- ciple, that in proportion to its antiquity or proximity to granite, mica schist becomes more felspathic and more quartzose, in fact, more like gneiss ; and on the contrary, that in proportion as it recedes from the fundamental rocks, it becomes more talcose, more chloritic, more argillaceous, in fact, more like clay slate. Examples of gneiss-like mica slate are found in Glen Tilt, Dalna- cardoch, and many other points of the Blair Atholl country, near Tyndrum, and sparingly around the granite mountains of Arran. In some specimens (Glen Roy) it appears composed of little else than mica folded and twisted round garnet crystals, in other cases (Ben Nevis) the garnets form almost distinct layers. In some cases (Glen Roy) the white mica and quartz form very smooth and atten- uated laminae, like those of cleavage, in others (Trosachs, Loch Earn) the quartz is in thick irregular plates, which mark one of the grada- tions to quartz rock. Quartz Rock in Scotland. Quartz rocks and quartzose mica slates are seen in the north of Scotland, in Moidart, along Loch Sheil and Loch Eil, and the eastern side of Loch Linnhe. Above the granite of Glen Tilt, quartz rocks abound in Ben y gloe, and several moun- tains round the granite of Braemar, and may be well studied in the valley of the Bruar, near Blair. They reappear in Mount Alexander, and on the sides of Loch Rannoch, constitute the pyramidal summit of Schehallion, and on the borders of the granitic desert of Rannoch Heath are traversed by granitic and porphyritic veins. Farther west the Island of Jura is distinguished by the obtusely conical quartzose mountains called the Paps of Jura, and the same rocks extend into Isla. Dr. Hibbert has described the quartz rocks in Zetland. Talcose Slates in Scotland. Talcose and chloritic slates, holding an intermediate mineralogical character between clay slates and mica schists, also for the most part occupy the intermediate geological position. They may be well studied on the banks of Loch Lomond and Loch Fyne, and several points on the south slope of the Gram- pians, where they are often rich in quartz, and remarkable for minute undulations and greater contortions. Chlorite slate is also found in 94 DISTEICTS OF GNEISS AIOD MICA SCHIST. the Long Island, and in Fetlar and Unst. The mica schist of the Highlands very generally contains garnets, which are of various size and occur under different circumstances. It seems difficult to ex- plain the very common association of garnets with mica schist and gneiss, except by admitting that this mineral is one of the effects of heat applied to those rocks since their deposition. Hornblende slate in Scotland. Hornblende rocks, especially horn- blende slate, occur in various combinations with mica slate. Horn- blende is seen plentifully in Glen Tilt, and is much traversed by granite veins, on both sides of the Pass of Killicrankie, south of Schehallion, north of Ben More, in the upper part of Loch Lomond, and under Ben Cruachan. Serpentine in Scotland. Serpentine, a rock whose geological rela- tions are very imperfectly understood, occurs in Scotland at many places, accompanied generally with talc or steatite, and diallage rock. It is said by Boue" to be most frequently placed among the upper beds of talcose slate, though occurrences of serpentine, in small quantities, accompany the limestones of lona, Glen Tilt, Harris, and Tiree.* On the south side of the Grampians it occurs only at Cor- tachie, on the North Esk, but through the north of Scotland its localities are more scattered. (Near Drimnadrochit, near Inverness.) The serpentine of Portsoy, said to be employed in some of the apart- ments at Versailles, forms " three vertical beds," one of them en- closed between hornblende rocks, another between hornblende rocks and primary limestone, and the third between quartzose talc slate and mica slate, which is covered by beds of limestone, hornblende slate, and talc slate, and the junction of all these rocks is softened by a mutual exchange of ingredients. In Scalpa, an irregular, highly inclined bed, one hundred yards thick, of serpentine traverses the gneiss promontory of the lighthouse, and exhibits at its boundaries against the gneiss abundance of hornblende crystals, layers of talc slate, and a sublaminated structure. It contains steatite, asbestus, &c. The granite veins here observed traverse both the gneiss and its included serpentine, and in the latter rock talc is superadded to the ingredients of the vein. Serpentine exists also in Lewis, and occurs in Zetland in consider- able abundance and beauty, both in the Mainland, in Fetlar, and at Brassa Sound in Unst, where it contains chromate of iron in suffi- cient abundance to be of considerable value in commerce. Potstone is found in Glen Elg, opposite to Skye, and in the ser- pentine of Scalpa. But the most remarkable rock of this kind is found at St. Catherine's, near Inverary, on the opposite side of Loch Fyne. It is imperfectly slaty, and has been employed in the erec- MacCulloch. BAFGE OF LIMESTONE ROCKS. 95 tion of the mansion of the Duke of Argyll. Boue also adds as localities, the districts of Strathearn and Breadalbane. Primary Limestone in Scotland Primary limestone. One of the most important of the subordinate or interrupted rocks which diver- sify the vast surfaces of gneiss and mica slate in Scotland remains to be noticed. So much has been before said on the composition of this rock, that we shall here dwell chiefly on the question of the relative ages of the different deposits. In the absence of organic remains, we can only examine the associated rocks, and the texture of the limestone itself. The white marbles of lona are found in a system of rocks by some referred to mica slate, but considered by MacCulloch to be gneiss. The variously coloured marble of Tiree, with its embedded augite and hornblende, lies in a system of alternat- ing gneiss and mica slate. That of Glen Tilt, characterized by its accompanying tremolites, lies in a quartzose mica slate, associated with hornblende slate. Notwithstanding the want of agreement in character between the limestones, and the more important differences between the rocks which enclose them, some geologists think these limestones are of the same age. Boue, following up the notices of MacCulloch, traces the line of the Glen Tilt limestones to the east and to the west. In the western direction they proceed from Gow's bridge, crossing the hills at Lude, and tending toward the south, pass through the Glen of Fincastle and across the valley of the Tumel. It is conjectured that limestone of the same range continues by Mount Alexander, and the base of Schehallion, from whence it proceeds through Glen Lyon to the side of Loch Tay, at the foot of Ben Lawers, reappears in Crien Larich, at the entry of Strath Fillan to the west of East Tarbet, in Knap- dale, and the head of the valley of Croe. Eastward from Glen Tilt, this limestone is traced in the course of the North Esk, and in the valley of the Dee, near Braemar, &c. So extensive a range of limestone rocks in the direction of the strata of mica slate, seems, indeed, to require little additional evi- dence of its being throughout a nearly contemporaneous deposit. The limestones on Loch Laggan and Loch Eil in Inverness, and at numerous other points in Aberdeenshire, are referred by Boue to the same era. Second Range of Primary limestone. A second range of lime- stones, lying chiefly in argillaceous and chloritic varieties of mica slate, is considered by the same author to be of more recent origin. The points are near Blairgowrie, at the foot of Ben Yorlich, on the north side of Loch Earn, Balquhidder, Inverary, Knapdale, and Lorn, and the limestones of Balahulish, Cairndow, and Dalmally, as well as those which run from Boharm to Bamff, are classed with these more recent limestones. 96 DISTRICTS OF GNEISS AND MICA SCHIST. Perhaps the relations between all these points may not have been correctly ascertained. In every attempt to trace a contemporaneous line through the older strata devoid of organic remains, much must be trusted to vague analogies ; but there seems excellent reasons for admitting that these calcareous rocks, like those which are more perfectly traced among the newer strata, were the produce of a few definite periods, and not mere irregular formations having no relation to each other in respect of time. The granite of the Isle of Man is followed by very little gneiss and mica slate, much Cambrian or Silurian schist (from which the mica schist and gneiss are metamorphic) , and quartz rock. The mica slate is traversed by veins of quartz and schorl.* North of Ireland The older strata of the north of Ireland may be considered as in part a prolongation of those of Scotland ; thus the extensive formation of mica slate in Londonderry and Donegal is on the line of the chain of the Grampians, continued through Jura and Isla ; and the clay slate ridges which border the Mourne mountains, run in the direction of the Mull of Galloway and the clay slate chain of the south of Scotland, while between these two systems of slates are carboniferous limestone, red sandstone, and other strata of newer origin, corresponding to those which separate the analogous chains in Scotland. The mica slate rocks are principally of the talcose varieties with- out garnets, but producing hornblende. Deposits of laminated primary limestone of different colours, containing talc, quartz, horn- blende, or pyrites, with veins of quartz, chlorite, and calcareous spar, occur in the mica slate, in many parts of Antrim and Londonderry. Hornblende slate likewise forms distinct beds in the mica slate of this region, and felspar porphyry is described as interposed under the same circumstances.f South of Ireland. In the south-eastern part of Ireland, granite is extensively seen, and mica slate forms two ranges along its eastern and western boundary, and wherever it occurs is in direct contact with the granite. On the eastern side of the granite it runs in a narrow course north-east and south-west, dipping steeply south-east, and consists of alternate layers of mica and quartz of extremely variable thickness. On the eastern brow of Rochetown Hill, mica slate runs into a natural hollow of the granite, still retaining the north-east and south-west direction of its strata. On Maulin Hill, it is singularly and fantastically contorted on the small scale. There is a prolongation of the body of mica slate at the head of Glenma- canass, gradually narrowed in its western progress, and constituting a wedge-like mass, inserted into the body of the granite, and en- closing a seeming bed of granite six to ten yards in width, besides * Henslow, in GeoL Trans. Cumming's Isle of Man. f Berger in Geol. Trans. BEITTANT PYEENEES. 97 irregular masses of granite incorporated with the slate. In the same vicinity, greenish, sectile, talc slate lies embedded in the mica slate, and is used for various purposes of architecture and sculpture. In Glenmalur occurs a remarkable instance of decided alternation of granite and mica slate, under circumstances very favourable for its display. In a space of 208 fathoms, no less than five distinct alter- nations of granitic beds, with as many layers of mica slate, are clearly traced, and several of these beds are compound, or really made up of similar alternations of granite and mica slate, or quartz and mica slate. The great mass of granite is below, and the great mass of mica slate above, constituting the hill called Lugduff. Grenatite abounds in this slate. Similar alternations occur in other neighbouring places, making a total thickness of one-third of a mile, and the whole system ranges north-east and south-west, and dips south-east. On the north-east they probably abut, and terminate against the granite. The mica slate on the summit of Lugnaquilla is likewise interstratified with granite. Clay slate bounds it on the east, and at length coming into contact with the granite cuts off its further progress to the south. On the western side of the granite the mica slate is still less ex- tensive. It is found to enclose beds and elliptical masses of granite in Grlenismaule ; and it is mentioned that a granite vein, four to eight inches wide, ranging 25 north of west, cuts off the mass of alternating strata, without occasioning any displacement. In the same valley are two distinct beds of compact greenstone porphyry in the mica slate, one four feet wide, the other two feet. Andalusite abounds in the mica slate of this country, and greenstones of various kinds alternate with it. The frequency of the phenomenon of alternation between mica slate and granite is a singular feature in the geology of this part of Ireland, for the full display of which we are indebted to Mr. Weaver.* in Brittany. The tract of old rocks in the north-western part of France is one of the most extensive in Europe. The granite, gene- rally the most elevated, is separated from the secondary strata by a system of gneiss and mica slate, and by another system, into which they pass almost indefinitely, of lower palaeozoic clay slates. In the departments of Calvados and La Manche, these two systems appear as zones around the granite, the gneiss being within the clay slate. Quartz rocks of blue colour, and pegmatites with tourmaline, are associated with them, and veins of quartz and granite traverse them.f in the Pyrenees. The granitic masses of the narrow chain of the Pyrenees having been uplifted in much confusion, are very irregularly Geol. Trans., vol. v. t De Caumont, Geol. du Cavaldos H 98 DISTRICT OF GNEISS AND MICA SCHIST. bordered ; in several places they are overlaid by gneiss and mica slate, but generally by the latter series. Charpentier, a disciple of Werner, thinks the gneiss of the mountains which border the valley of Soulan so intimately connected by gradation and alternation with the subjacent granite, as to be necessarily united therewith into one formation. In many instances gneiss and granite are described as alternating in very thin layers. In other cases, vast blocks of mica- ceous gneiss of 100 cubic fathoms' bulk are buried at intervals in granite, always preserving one constant relative position or direction of strata. These are thought by Charpentier to be of contempo- raneous origin with the granite, which passes into them at the sides, and thus interlaminates the gneiss. Mica slate, in the same manner, is intercalated with granite in a great many places, and quartz and felspar bands occur in the granite. In many places in the Pyrenees the * granite' contains beds of stratified granular limestone, (such as in other districts lies in the gneiss,) with graphite, talc, fluor spar, mica, hornblende, &c. The more modern view of these phenomena is that they are quite consistent with the doctrine that granite is an igneous, but gneiss and mica slate originally aqueous rocks, and that in some cases what is called granite, is in fact gneiss with the aspect of granite, derived from a more than usual condensation and greater effect of heat. Boue, Dufrenoy, and other writers, have proved beyond a doubt the powerful action of heat along the Pyrenean chain, as evinced not only by the usual subcrystalline character of the clay slates, but also by the metamorphism of the chalk into the characters of primary limestone, with abundance of metallic and granitic veins at the line of junction of the altered stratified and the igneous rock. The age of the eruption of granite along this chain is, by observations of Dufrenoy, determined to be, at least in part, posterior to the chalk. It is extremely probable that the same kind of explanation will be found to apply equally to the alternation of granite and slates in Ireland and Cornwall, and to the alternations of porphyry and slate in Cornwall, North Wales, and Cumbria. It is to be remembered, however, that the igneous theory, as it has been termed, does not by any means require that all these beds of seeming granite should be pronounced to be altered gneiss, nor that the beds of porphyry should be considered as altered clay slate. Alternating igneous and aqueous action is perfectly intelligible, and exemplified in modern operations of nature ; but certainly in many cases, both in Cornwall and Cumbria, it appears the more correct view to suppose a gradual and partial rearrangement of the materials of the rock, through the long action of heat. This would well agree with the indefinite boundaries of the porphyries of Cornwall and Cumbria, which often pass by insensible modifications into ordinary slate. FBAFCE, ETC. 99 in Central France. The great central plateau of old rocks in France from which the Loire, Vienne, Dordogne, &c. take their source, is chiefly a granitic and porphyritic tract, surrounded by oolitic and carboniferous rocks, but clay slates and gneiss rocks appear in the valley of the Vienne, and occupy a large part of the southern boun- dary. Near Limoges are alternating beds of granite and gneiss, and some subordinate beds of pegmatite and hornblende rock ; the gneiss passes by one variation to granite, by another to mica slate. The ranges of the strata near Limoges are north-east and south-west, and they are crossed by decomposing elvan courses to north north- east. Tin veins occur near Vaulry in gneiss as well as in granite. Towards the borders of the district the gneiss becomes less granitic, more associated with hornblende slate, and encloses deposits of mica- ceous limestone. Serpentine lies in this gneiss in many places, and M. Cordier appears disposed to refer them all to one contempora- neous, though interrupted deposit. The pegmatites and kaolins of St. Yrieux, which have resulted from them by decomposition, form numerous veins and strings in the gneiss and hornblende slates, which sometimes intercalate themselves between the laminae. Quartz rock of bluish colour exists likewise in the Black Mountain and elsewhere. Oxidulated iron abounds at many points in the gneiss ; galena, phos- phate of lead, carbonate of copper, antimony, and haematite, are the products of the veins.* The most remarkable alterations of secondary limestones take place, according to Dufrenoy, along the line of junction with the granitic and porphyritic masses. Thus the lias and oolite become metamorphic, and are traversed by metalliferous veins, as in Corn- wall and Brittany, where the slates are metalliferous principally in the same situation. Other localities in Europe. After these details of the circumstances attendant on gneiss and mica slate at so many interesting points, we shall only add some general observations on the range and extent of this system of rocks in other countries. Gneiss and mica slate in small quantity occur in the Vosges, and gneiss more abundantly in the Black Forest. The long irregular chain of the Alps contains a vast quantity of gneiss and mica slate, variously extended around the talcose granite cores of Mount Blanc and St. Gothard, from the Mediterranean almost to the Danube. The age of this gneiss may be matter of doubt. Deeply buried beneath the valley of the Danube, gneiss and mica slate do not reappear around the granitic origin of the Carpathians. Their place is supplied in this chain by a vast deposit of clay slate. The primary mountains which encircle Bohemia are, on all the southern half, granite. Gneiss and mica slate are superadded on the * Desnoyers 100 DISTEICT OF GNEISS AND MICA SCHIST. west, and the former rock in particular abounds in the Erzgebirge. The Riesengebirge granite is bordered on the north by gneiss, on the south and east by mica slate, and these rocks are associated with granite in the range which divides the drainage of the Oder and the Elbe. These rocks are most extensively spread over the northern parts of Europe, from Copenhagen round the Gulf of Bothnia, along the Uralian chain toward the Caspian Sea and the Caucasus. in America. In America, Humboldt describes gneiss as less abun- dant along the high chains of the Andes than along the inferior mountains of Caracas, in Oronoko, Brazil, New Spain. It is occa- sionally auriferous, and contains micaceous, primary limestone. The most considerable masses of mica slate mentioned by this distinguished traveller are those of the Cordillera of the shore of Venezuela. This formation in the Andes is less rare on the north than on the south of the Equator. Nowhere, perhaps, is the total suppression of mica slate formations more frequent than in the Cordilleras of Mexico and South America. The eastern primary range of North America passes through the United States from the St. Lawrence to the Mississippi in a direc- tion nearly parallel to the coast, and generally 100 miles distant from it. The prevailing and characteristic rock is a syenitic gneiss, in which the divisional planes are obscure, and frequently evanescent, when the rock is undistinguishable from the syenite which forms part of this great metamorphic group. Gneiss retains in general its place next the granite, which, however, is in small extent ; it is often succeeded by hornblendic, micaceous, and talcose schist, and granular, sometimes dolomitic limestone, seldom pure enough for fine statuary. It is traversed by granite veins at Haddam, in Connecticut. This is the principal metalliferous band in the United States, yielding magnetic iron ore in veins and beds, near Lake Champlain, in New York, New Jersey, Pennsylvania, and Maryland ; on the southern side of Lake Superior, in the vicinity of Montreal, in Wis- consin, in the Iron Mountain and Pilot Knob in Missouri, and in Arkansas. Copper ore occurs in Lake Huron, and on the northern shore of Lake Superior. Lead ore lies in these rocks in northern New York; lead and copper in Pennsylvania; zinc or red oxide, mixed with franklinite, occurs in New Jersey ; phosphate of lime has been found in New York and New Jersey ; kaolin marble, build- ing stone, firestones, hones, steatite, plumbago, and many fine crystallized minerals, as apatite, zircon, spinelle, sphene, augite, tourmaline, may be added to this list. The range of the rocks is from the high country north of the St. Lawrence, westward to the sources of the Mississippi, and south- AMEEICA. 101 ward along the elevated ports of Maine, New Hampshire, New York, New Jersey, Pennsylvania, Maryland, Virginia, and North Carolina, to Alabama, with isolated belts in Missouri, Arkansas, and Texas.* CHAPTER VI. LOWER PALEOZOIC STRATA. For the purpose of clearly unfolding the relations of the various argillaceous, arenaceous, conglorneritic and calcareous rocks which comprise the vast and variable series of the lower palaeozoic strata, it is desirable to fix our attention upon districts where the variety of the rocks is considerable, the section ample, and the order of suc- cession perfectly known. We commence with the districts of the English Lakes, and the picturesque valleys of Wales. As early as 1818, Mr. Jonathan Otley of Keswick had arrived at a general classification of the slate district of the lakes in three divisions. In 1821, Smith used this classification ; in 1822 I dis- covered upper silurian fossils, as they would now be called, near Kirkby Lonsdale.f In that year Professor Sedgwick obtained his best fossils from the same neighbourhood, under the guidance of Smith,;}; and in many succeeding years of toil he has followed out his admirable observations with unconquerable patience and perse- verance, and has, in fact, mastered all the difficulties of detail, in the beds above the green slate, which no one can over-estimate. The following is a transcript of his latest classification : 6. Group from Benson f Tilestone and red Calcare0 us flagstone. no , sou i en-- ft Q r - lis and coarse flagstone, without transverse cleavage. MooJ rfhe Lune^ " Coarse slates, &c, with occasional transverse cleavage, ii ^ T- i ^ ivT^fl north of Kendal Fell, forming a passage into the Ca.lJ.6Cl j\.lrK D y group d. Coarse striped slates alternating with beds of gritstone, much contorted and of great thickness, c. Great or Upper Ireleth slate ; no traces of Aymestry 5. Ireleth slate group. limestone. b. Ireleth limestone in a discontinuous and concretionary form, a. Lower Ireleth slate. 4. Coniston grit ( Coarse hard gritstone, conglomerate, and thin bands of (Transition group.) \ slate. Collectively of great thickness. * Lyell in Report on Industrial Exhibition of New York, 1854. Trans, of Geol. Society, 1829. \ See " Letters " in Wordsworth's Survey of the Lakes. Trans, of the British Association, Report for 1653. 102 LOWER PALAEOZOIC STKATA. 3. Coniston limestone (b. Coniston flagstone and calcareous slate. group \a. Coniston limestone and calcareous , slate. 2 p . , ( Great beds of roofing- slate, &c., alternating indefinitely a -c with porphyry, trappean conglomerate, trap-shale porpnyry ^ shaalstein, &c., collectively of enormous thickness.* PC. Masses of gritstone, rarely of coarse texture. b. Mountain masses of black slate, with veins of quartz, 1 Qv/q/i i t not en ervescm g with acids. ate | a. Beds of porphyritic chiastolite slate, passing (when near the granite) into chiastolite rock, and beds which L are entirely metamorphoic. Nearly all that is valuable in the geology of 'the slate system of Wales is due to Henslow's description of Anglesea, Sedgwick's labours in Snowdonia, and all its intricate dependencies, Murchison's detailed investigation of the south-east portion of the district from Shrewsbury to the mouth of the Towy, and the arduous labours of the geological survey. In the north-western district, the general inferiority of position of the chloritic and micaceous schists to the whole clay slate system of Wales is clearly proved ; the true place of the Snowdonian shells fixed in the parallel of Bala and Llandilo, the extent and effects of subterranean convulsion and intrusion of igneous rocks, very fully pointed out. The south-east border, de- scribed by Murchison, fortunately presents a series of phenomena, deficient or not clearly separated in the great slate district of Cum- bria a vast number of organic remains, lying in distinct groups, a series of distinct members of the formations which these fossils ap- pear to characterize, limestones of different ages which clear up the difficulty, always felt previously in fixing the true relations of the limestones of Dudley and Llandilo ; and finally, ancient Plutonic operations accompanied by elevations and alterations of the strata. We may now, upon sufficient data, affirm that the Welsh and Cum- brian series of slates presents a nearly complete record of all the principal deposits, with their characteristic organic remains from the gneiss and mica schist, upwards to the carboniferous system ; and thus to show a continuity of marine operations in a part of the geological scale of periods where, in the time of Smith, was an utter blank. In Wales, and on its eastern border, according to the now nearly united testimony of Sedgwick, Murchison, and De la Beche, (com- prising, under this last honoured name, Ramsay, Selwyn, and the staff of the geological survey,) we have the following clear general section : * Some rare examples, probably in the upper part of this great group, of black slate with fucoids and graptolites. AEEAKGEMENT WALES. 103 L O W E E PALEOZOIC. Mg ! O * 3 B 1 BB J??a^ il & i crq n CAMBRIAN. td SILURIAN. Lower No fossils Fossils Fossils known. few. abundant. e.fc-8 1 H. 5' 5 |i *l c q 5 s; | 8S || ! P : : : s. s. I I: F ? I Upper Fossils abundant, abundant. A ^ t A ^ m CD ,,j ( _. Bohemia. Under the lowest zone of primary strata yielding fossils, are thick masses of earlier sediments, conglomeritic, arenaceous, and argillaceous comparable to the " bottom zone" of North Wales like that more or less slaty, and banded with trap rocks. These rest upon gneiss and granite. The lowest fossiliferous zone is called by M. Barrande, the zealous and persevering explorer of the Bohemian Basin, the * primordial' ; it is an argillaceous series, comparable to the Festiniog or Lingula 104 LOWER PALAEOZOIC STEATA. zone of North Wales, and contains paradoxides, agnostas, &c. Igneous eruptions followed. The zone which follows is composed of conglomerates, sandstones, and schists, contains trinuclei, ogygiae, illa3nidas ; it is the typical zone of the lower silurians of Murchison, including some black shales, but without the calcareous elements of Bala and Llandilo. The fossils in these shales are partly upper silurian, and are regarded as early colonies from some other region, in which those zones prevailed. Black schists with graptolites succeed, enclosing interposed bands of greenstone and trap. (Transition group.) Next follow upper silurian grey argillaceous limestones, with car- ditse, phragmocerata, orthocerata, pentamerus knightii, rhynconella navicula, and many other Wenlock or Ludlow species. This stage contains no less than seventy-eight species the genera being mostly Wenlockian and Ludlovian. Two other bands of limestone ranging in great conformity succeed, and contain the same and analogous fossils. Grey shales form the highest observable silurian rock. The uppermost of the three limestones contains calymene, but also ex- hibits some Devonian affinities, by its included genus of goniatites, and some brachiopoda, which specifically are the same as Devonian forms. Remains of fishes He rarely in the uppermost grey shale.* On attentively considering the three complete sections now given of Cumbria, Wales, and Bohemia, complete because they begin above hypozoic and end below Devonian strata, and giving full weight to mineral as well as organic associations, the reader cannot fail to be struck with the essential accordance between them all. We have always two great zones, which may be thus defined. Upper Zone Contains limestones, and very numerous forms of invertebral marine life, trilobites, orthocerata, phragmocerata, crinoidea, cystidea, zoantharia, &c. Divisible into two parts, this is the original Silurian system of Murchison. The two parts connected by a transition band (upper caradoc). Lower Zone, without limestones, contains few forms of life, especially lingulae, para- doxides, conocephalus, of species perhaps entirely, and genera mostly distinct from those above. This zone divisable into two parts ; the upper having in certain parts a poor fauna ; the lower not yet found to yield any forms of animal life. The upper part is the primordial zone of M. Barrande, the lower part is the bottom zone of the government survey. Together they constitute what was formerly un- derstood or supposed to be the subject of Sedgwick's special inquiry in Wales, and called the Cambrian system. Finally, if we regard only the organic associations, the whole is but a great system of life, varying with time and local conditions, growing, expanding, and again contracting, to give place, at least * Tin's abstract is taken from 'Siluria,' Sir R. Hutchison's latest view of the system of strata with which his name is indissolubly linked. P. 340, et seq. HALL'S CLASSIFICATION. 105 Upper Silurian: many Fossils- Lower Silurian: many Fossils. Upper Cambrian: few Fossils. Lotver Cambrian: few or no Fossils. '.'\ f^-^Z'2 '-. Mayhill Sandstone. Upper Ludlmv. Aymestry Limestone, Lower Lwllow. Wenloek Limestone . Wenlock Shale. Woolhope Limestone, &e. Caradoc Sandstone. Upper Bala, Slates, Flags, &e. Bala Limestone. Lower Bala, Slates, Flags, &. OLENUS, 4 Ior4?. 3? , ';j. PARADOXIDES, 1 1 Phacops, 15 15 3 Proetus, 3 .... 1 3 Remopleurides, 7 7 Fphaerexochus, 1 .... 1 1 Staurocephalus, 2 2 Stygina, 2 2 Tiresias, 1 1 Trinucleus, 5 5 (OTHER ENTOMOSTRACA.) Beyrichia, 3 2 t Ceratiocaris, 3 3 Cythere, 1 1 . 126 LOWER PALEOZOIC. Dithyrocaris, Eurypterus, HTMENOCAKIS, Leptocheles, No. of Species. 1 2 1 2 1 Lower Stage, (Cambrian.) Middle Stage, Up. Stage, (L. Silurian.) (U. Silurian.) 1 2 Cellepora, Ceriopora, Diastopora, Discopora, Escharina, FENESTELLA, Glaitconone, Heteropora, Intricaria, OLDHAMIA, Polypora, Ptilodictya, Retepora, Aihyris, Atrypa, Chonetes, Crania, Cyrtia, Discina, Leptaena, LlNGULA, Obolus, ORTHIS, Orthisina, Pentamerus, Porambonites, Retzia, Rhynconella, Siphonotreta, Spirifera, Trematis, AmbonycWa, Avicula, Inoceramus ? Posidonomya, Pterinea, Anodontopsis, BRYOZOA. 1 ..... 5 2 3 1 1 6.1. 1 ... 1 1 2 . 1 1 8 1 6 1 BRACHIOPODA. 9 1 1 3 1 1 12 42 16 2 6 28 1 . 8 45 2 8 3 3 1 . 39 2 4 2 26 2 5 1 10 1 1 1 LAMELLIBRANCHIATA. MONOMYARIA. 6 16 2 1 10 DIMTAEIA. 7 6 8 1 2 1 6 17 6 2 11 "5 1 3 17 1 4 OEGANIC BEMAItfS. 127 Area, Cardiola, Cleidophorus, Conocardium, Cypricardia, Dolabra, Grammysia, Modiola, Modiolopsis, Mytilus, Nucula, Orthonota, Psammobia ? Sanguinolites, Tellina ? Conularia, Ecculiomphalus, Pterotheca, Theca, Capulus, Euomphalus, Helminthochiton, Holopea, Holopella, Loxonema, Maclurea, Macrocheilus, Murchisonia, Natica, Nerita, PateUa ? Phasianella, Pleurotomaria , Raphistoma, Trochus, Turbo, TurriteUa, No. of Lower Stage, Middle Stage, Up. Stage, Species, (Cambrian.) (L. Silurian.) (U. Silurian.) 4 2 6 1 1 2 4 2 4 5 6 3 1 10 1 12 3 7 3 2 2 8 1 1 2 1 4 2 6 i . 8 7 13 3 1 6 4 2 7 1 10 1 PTEROPODA. 3 3 . .. 2 3 GASTEROPODA. Actinoceras, Cyrtoceras, Lituites, Orthoceras, Phragmoceras, HETEROPODA. 13 CEPHALOPODA. 3 3 11 54 10 n, 2 16 1 2 9 2 1 10 1 ,. V 2 4 . 2 1 14 1 2 1 9 ., 1 1 1 10 2 8 10 4 ; TH rH CO rH CO CO TH ' -. 1 2 6 24 4 1 5 33 128 LOWEE PALEOZOIC. Onchus, Plectrodtis, Sphagodus, Thelodus, FISHES. No. of Lower Stage, Middle Stage, Up. Stage, (Cambrian.) (L. Silurian.) (U.Silurian.) Species. 2 3 1 1 On this list we may base some convenient numerical estimates. Assuming, as a general term of comparison, the number 1,000 to represent a total, we have the several groups of life represented in the Lower Palaeozoic strata by the following numbers : Mostly Marine. It is doubtful whether they be really such. Many more may be expected. Amorphozoa ? . A j- 4 Foraminifera, . 1 Zoophyta, . . 142 Echinodermata, 58 Annelida, . . 23 Cirripeda, . . ... Crustacea, . . 154* Insecta, . . , ... Tunicata, ... Bryozoa, . . 35 Brachiopoda, . 216* Monomyaria, 40 Dimyaria, . . 105 Pteropoda, . . 11 Gasteropoda, 100 Cephalopoda, . 93 Fishes, . . . 8 Reptilia Birds, . . . Mammalia, . And if, with the same assumed total (1,000), we count the species in the three several great groups, we have the subjoined result : In upper group (Upper Silurian), In middle group (Lower Silurian, In lower group (Cambrian), 496 485 19 Here we see numerically the most decided analogy between the upper and middle groups, the most positive contrast between them and the lower group. In regard to the former statement we may add that the numerical proportions for the different great groups of life are much alike through the upper and lower Silurians. Thus in each case the bulk of the species is made up of zoophyta, crus- tacea, brachiopoda, dimyaria, gasteropoda, and cephalopoda, the proportions running thus in the silurian groups of strata : Plants, . Amorphozoa, Foraminifera, Lower Silurian. O Upper Silurian. 1 1 1 CAMBRIAN FOSSILS. 129 Zoophyta, . . 62 Echinodermata, . 2 Annelida, 14 Crustacea, . 111 Bryozoa, . 10 Brachiopoda, 116 Monomyaria, . 20 Dimyaria, 37 Pteropoda, . 8 Gasteropoda, . 67 Cephalopoda, Fishes, 41 Lower Silurian. Upper Silurian. 85 11 47 24 101 19 63 5 48 52 10 The most obvious contrasts are in the relative superiority of Crustacea in the older group, and of echinodermata in the younger ; fishes being as yet confined to the upper. CAMBRIAN FOSSILS. 31 Oldhamia antique Brayheacl, Wicklow. 32 Hymenocaris vermicauda. Bangor, North Wales. 33 Olenus micrurus. North Wales. 34 Lingula Davisii. North Wales, 130 LOWEB, PALEOZOIC. LOWER SILURIAN FOSSILS. 40a 35 Halysites catenulata. 37 Diplograpsus pristis. 39 Echinosphaerites aurantinm. 36 Heiiolites inordinata. 38 Didymograpsus murchisoni. 40a Nereites cambrensis. LOWEE SILUKIAN FOSSILS. 131 406 41 42 43 47 40& Trinucleus ornatus. 41 Ogygia Buchii. 42 Agnostus pisiformisi 43 PtUodictya dichotomy 44 Orthisflabellum. 45 Siphonotreta micula. 46 Ambonychia triton. 47 Maclnrea LoganL 48 Lituites cornu arictis. 132 LOWER PALAEOZOIC. UPPER SILURIAN FOSSILS. 40 Arachn Arachnorliyllum typus. 51 Cyathophyllum truncatum. Cystiphyllum cyliniricnm (cut;. 52 Favosites gottlandica. TPPEE SILURIAN FOSSILS. 133 53 Eucalyptocrinus decorus. 55 Calymene BlumenbachiL 58 Rhynconella Wilsoni. 54 Tentaculites ornatus. 56 Phacops caudatus. 59 Spirifera plicatella. 54a Magnified view. 57 Orbicula Forbesii. 60 Atrypa reticularis. 61 Strophomena filosa. 62 Strophomena depressa. 134 LOWEE PALEOZOIC TJPPEE SILTJEIAN FOSSILS. K3 Pentamerus Kniglitii. (54 Pentamerus galeatus. 65 Euomphalus discors. 66 Conularia sowerbii. 69 Orthoceras aimulatum. 67 Phragmoceraspyriforme. 68 Phragmoceras ventricosuir PHYSICAL GEOGBAPHY. 135 CHAPTEE VII. MIDDLE PALAEOZOIC STRATA. Physical Geography of the Period. On passing to another great life period in the formation of the stratified crust of the earth, that dur- ing which the old red strata were deposited, the surface of the globe, as far as this can be known from observations so long posterior, was in a very different state from that which has been inferred to have been its condition before the deposit of the Lower Palaeozoic strata. Then it is probable that little dry land existed, and perhaps most of the mechanical aggregates of the Silurian series were produced by agitations of the comparatively shallow waters of the ocean ; but now many mountain ranges and groups may be traced dividing the ocean into seas and gulfs of various depths and unequal area, within which materials swept forcibly by inundations from the land were mingled with chemical precipitations and remains of life from the water. Thus the primary ranges of Scotland, England, Wales, and Ireland, the south of France, and the north of Germany, are in many parts enveloped in thick strata of conglomerates, sandstones, shales, coal, and limestone ; and these deposits begin to assume more local characters, dependent on the varying physical conditions of the par- ticular case. Even in the limited area of the British islands, to which we shall mostly confine our special illustrations, the Middle Palaeozoics ex- hibit two clearly marked types : one, the Scottish, Cumbrian, Eng- lish, and Welsh type, of old red sandstone and red marls, with local conglomerates and concretionary limestones, poorly fossiliferous ; a type found also in Man, and the north of Ireland ; and the other the Devonian and Cornish type, of slates, compact limestones, red and gray sandstones, some of them rich in organic remains. This type occurs in many parts of Europe, and may be pretty well identified in North America, in Africa, &c. Each of these groups of deposits is generally very distinguishable from those of the primary group ; most remarkably so, where, as is generally the case, their accumulation was preceded by a great eleva- tion of the older strata, but in several instances the change from the older rocks to the shales and sandstones of the superior group is very gradual (Herefordshire), and unaccompanied by violence, and the organic remains are often congeneric. It is not then a new creation, nor even a new system of nature, that we are called upon to examine, but another step in the scale of periodical operations, whereby the vacant planet was replenished with life, and fitted for the residence of man. 136 MIDDLE PALEOZOIC STRATA. Scotland. The old red sandstone is largely developed in Scotland, especially along the south-eastern edge of the Grampian mountains, and on the north-western side of the slate ranges of Lammermuir, from Dunbar to the coast of Ayrshire, as fully described by M. Boue. It appears in the valley of the Tweed, and about Jedburgh, Cold- stream, Melrose, and Dunse. It forms in Arran the lower portion of one vast red sandstone series, the upper portion of which, not very different in -any of its characters, is taken by Murchison and Sedgwick for the representative of the new red sandstone of England. On the western side of Scotland the old red sandstone is found at many scattered points in bays and hollows of the mountains, and has received very good illustration from MacCulloch and the geologists above named. Along Loch Ness ; about Inverness, Nairn, Forres, and Elgin ; in almost the whole circuit of the Moray Firth ; along the coast of Caithness, and occupying the whole of the north- eastern promontories to the Pentland Frith, strata of this age abound, and the Orkneys appear to consist chiefly of the same group of rocks, which also extend into Shetland along the coast from Sumburgh Head to Lerwick. In the Orkneys the principal members of the group are dark, car- bonaceous, and micaceous flagstones, with fishes of the genera dip- terus, osteolepis, cheirolepis, &c. In Caithness, the same strata recur, covered by red sandstones, and resting on conglomerates. Almost universally this red sandstone system, how various soever in thickness and in quality of composition, consists in all the lower portion, which rests upon the slate system, of a coarse conglomeritic sandstone, generally tinged red, full of fragments large and small, and rounded by attrition in water. This rock does not, like that of Cumberland, to which it is strongly analogous in composition, lie entirely in local hollows, but forms a continuous belt round nearly the whole primary district, where the border of this is distinctly seen, and rises into hills of considerable altitude, which are in this manner wholly composed of the ruins of the interior and still higher primary mountains. The contemplation of this remarkable rock in the vicinity of the beautiful lakes in the south-west part of the Grampians, can hardly fail to impress upon the attentive observer two propositions of the highest importance in geology. 1st, That the accumulation of these mountainous ruins of earlier rocks was caused by the violence of water, put into activity by the elevation of the primary rocks, and favoured in operation by the fractures which this operation produced in them. 2d, Tha't since all these effects, the whole region of primary and derivative rocks has been again elevated, perhaps by a more insensible process, so as to raise the con- glomerates to the height of 10,000 feet or more above the level of that sea in which they were formed. PHYSICAL aEOGBAPHY. 137 According to the nature of the primary rocks in its vicinity, as remarked by M. Boue, the red sandstone conglomerate varies in composition. The degree of attrition to which the fragmentary masses which it includes have been exposed, is here different in dif- ferent places ; without doubt according to the degree and continuity of the aqueous action accompanying the disruption of the primary strata. Thus, on the banks of Lochness, at the Fall of Foyers, we find it a sort of granitoid breccia, with fragments slightly rolled of quartz, mica slate, red granites, primary limestones, &c. We might easily admit that this granitoid breccia is in some degree meta- morphic, like certain breccias of Plutonic aspect in the slate district of Cumberland. The brecciated character, so remarkable at the Fall of Foyers, is speedily changed at a small distance into the usual aspect of a decided conglomerate. Along the south-eastern edge of the Grampians, the composition of the conglomerate appears dependent in a high degree on the nature of the primary series on which it reposes. Near the granitic and porphyritic region of Aberdeenshire, quartz, felspar, porphyry, granite, with garnets, syenite, hornblende, compact felspar, are men- tioned by Boue, with gneiss, mica slate, and clay slate. But in the district of Loch Katrine, where Plutonic rocks are less abundant in the slate system, the fragments consist almost wholly of mica slate and chlorite slate. In Oban we have observed that the rock contains not only masses of trap rocks, but that its base is in places almost wholly composed of the substance of those rocks reduced to sand. Along the Lammermuir ranges, which are composed of older slate and trap rocks, the conglomerates contain almost wholly slate fragments and boulders, and lie in hollows of the chain, very much as the contemporaneous deposits border the similar slates of Cumbria. The inclination of the conglomerate strata is dependent on the configuration of the primary mountains, and there is no doubt that the stratification is for great lengths of country in irregular accor- dance with that of the older rocks ; yet this dependence is chiefly observed along the lines parallel to the axis of elevation of the Grampians, and is even there liable to great exceptions. In the vicinity of Loch Lomond it succeeds clay slate ; generally along the Grampians it rests on mica slate or chlorite slate ; but along the Lammermuir hills on Cambrian and Silurian rocks. Receding from the border of the mountains, the upper strata of red sandstone are found nearly free from pebbles, composed of laminae of various quality, sandy or argillaceous ; and sometimes, as in Perth- shire, variously coloured. The Caithness graystones probably belong to this central division, or to a somewhat earlier date. To the upper part of the group belongs the remarkable series ^f^ lishes, and the solitary reptile of Elgin, named by 138 MIDDLE PALAEOZOIC STEATA. peton Elginense. Red sandstones accompany the coal of Dumfries- shire, and pass gradually into the limestone and coal series of the Lothians and Tweeddale, so that where, as in Arran, the limestone and coal are very thin, the whole has the air of a great continuous deposit, in which the carboniferous limestone and coal seams form merely the parting, not always traceable, between the old red and the new red sandstone systems. A geologist in the southern parts of Scotland, working without reference to other parts of the island, might think himself justified while including the carboniferous and saliferous systems in one general term, "the red sandstone system ;" having, as subordinate groups, the mountain limestone and coal strata. More extended research and a sound view of palaeontology would soon correct the error ; we must, however, remember that what has been sometimes called new red sandstone, has appeared to later observers a part of the Eotheliegende, the lowest member of the Permian system. Taking the most general view of the whole Scottish series of the old red, we find, with Miller,* in the north of the district, Upper Part Conglomerate sandstone, concretionary limestone. The principal and characteristic fish is Holoptychius nobilissimus. (Sil. Syst. pi. 2 bis.) (In other districts the conglomerate and limestone fail.) Middle Part. Gray sand and dark flagstone. The characteristic fish is Cephalaspis Lyellii. (Sil. Syst. pi. 1.) Loicer Part. Red and light coloured sandstone, (perhaps here also the calcareous schists of Caithness and Orkney.) Sandstone, clay, and calcareous nodules, with pterichthys, coccosteus, and other fishes. The basis of the series is generally a thick mass of rude conglomerate, in mountainous masses. Old Red Sandstone Formation in England. Origin of this Formation. Proceeding now to the district of the English Lakes, we arrive at a case where the production of this rock is evidently modified by the eifect of general convulsive movements. The slate rocks of Cumbria, exposed upon their recent elevation to enormous waste and degradation, were rolled to pebbles, which were collected into hollows or rude valleys, and reunited by a basis of red sandstone or red marl into vast irregular beds of coarse conglomerate. in the Cumbrian District. The limited tract of old red sandstone adjoining to the slate district of Cumberland and Westmoreland, lies principally on the eastern side, where it appears in patches, in Mell Fell, at Dacre Castle, Sedbergh, and Kirkby Lonsdale, and near Kendal. In all these situations it is a very coarse conglomerate, with a basis of red sandstone or red marl, filled with fragmentary * See his excellent volume entitled ' Old Red Sandstone.' OLD BED SANDSTONE FOEMATION. 139 masses, almost entirely derived from the neighbouring slate hills. Some of these fragments are quartz veinstone with micaceous iron ore ; others are derived from the Coniston limestone. Each little patch of conglomerate is nearly confined to a particular valley, and seems, in fact, to have been accumulated by currents which in the ancient times of disturbance passed down that hollow. No organic remains have ever been found in this rock around the district of the Lakes, except in the rolled pebbles of Silurian slate or limestone. In some places the quantity of pebbles is diminished, and the red sandstone forms separate beds (Shapwells) ; in other places the red clay, alternating with blue and white layers (as at Kirkby Lonsdale), I 1 a 70 a Silurian uncouformed to, b Old Red, and c Carboniferous. so closely resembles the new red marl, that nothing but the geolo- gical relations could determine the difference of the deposits. As might be expected in such a heterogeneous mixture, the beds and joints of the conglomerate are irregular, and it deserves atten- tion that hitherto no mineral veins have been found to traverse it. Veins of calcareous spar occasionally divide it, and, what is remark- able, the pebbles are often split by these veins, as they are in the contemporaneous conglomerate of Oban in Argyllshire, and the more recent Nagelflue of Swisserland. Above the conglomerate in the valley of the Lune and other places we have red clays, with concre- tionary limestone, neither in great thickness, apparently conformed in position to the limestone series above. It appears from these circumstances, that during the period of turbulence which succeeded the deposit of the slates in Cumberland, the waters of the sea had a particular tendency to deposit, near the shores, materials charged with red oxide of iron, and that the com- paratively quiet process by which sandstones and clays were thus pro- duced was liable to violent interruptions, and the products in conse- quence mixed with a vast quantity of fragments of the preconsoli- dated rocks, probably urged downwards to the sea along the lines of dislocated strata which had already begun to be excavated into valleys. Deviating a little to the east, we find under Ingleborough and Penyghent, an old elevated Silurian shore, worn smooth by the sea action, and covered, not by old red, but by mountain limestone. A similar deficiency of old red occurs round the Cambrian rocks of Charnwood, and the Silurians of Nuneaton. There is no old red 140 MIDDLE PALJEOZOIC STRATA. above the Silurian limestones of Dudley, and hardly more than a trace of it above the Silurians of North Wales and Salop, from Con- way to Coalbrook Dale. This absence may perhaps be in part due to unconformity ; there may be some old red beneath parts of the limestone and coal of this tract named, but on the whole we think there is ground to admit that a large area of the Midland counties and the north of Wales is deficient of these rocks, an opinion which their evidently local character confirms, and even renders necessary. in Wales. Along the south-eastern and southern border of the slate district of Wales, from Coalbrook Dale, through Herefordshire, Monmouthshire, Glamorganshire, and Pembrokeshire, the old red sandstone formation is of vast thickness, fully developed, extensively spread out, composed of various definite parts, and regularly trace- able through the country. Its boundary on the west is by Haver- ford-west, Caermarthen, Llandovery, Knighton and Ludlow. On the east it runs from near Cardiff, by the high district of Went wood, Trelech, and Craig y Dorth, and by the Forest of Dean, which it encircles with a high boundary edge, the west of Mayhill, the Malvern and Abberley hills, to the Severn near Bewdley. Its thick- ness in Monmouthshire and Breconshire can hardly be estimated at less than 5,000 to 8,000 feet, but its lower edge is not always clearly distinguishable from the Silurian strata beneath. In fact, about Pont ar y llechau, near Langaddoc, the marly beds of the old red alternate with true Silurian strata, containing characteristic fossils. From the mountain limestone series above it is in general sharply defined. In the district of Tortworth, a yellowish sandstone appears along the junction line. Monmouthshire, &c. One of the best sections of the old red sand- stone is afforded in the neighbourhood of Monmouth, beginning with the Kymin Hill, which is part of the lofty boundary of Dean Forest. Here we perceive that the thick conglomerate rocks, full of quartz pebbles, remarkably analogous to some varieties of millstone grit, form the very cap of the whole system, and crown the hills with magnificent precipices and solitary crags. Below is a series of red sandstone rocks, productive of excellent flagstone, with one, or per- haps two, beds of a singular limestone, mottled with red, blue, green, and yellow, sometimes much mixed with clays, and always irregular. Though of argillaceous aspect, it is so nearly pure as to be burned to lime ; and though apparently fragmentary, is really a very hard stone, fit for the roads. It contains no organic remains in this vicinity, but elsewhere few remains of Cephalaspis and other fishes occur in it. The lowest part of the section exhibits an extreme abundance of red marls with white and green bands, hardly distin- guishable from those of the new red marl. OLD BED SANDSTONE FORMATION. 141 These characters accompany the range of the old red sandstone through the lower parts of Monmouthshire, and through Hereford- shire, and part of Worcestershire, where the upper conglomerates are used as cyder millstones, and the limestone (called cornstone) is often employed on the roads. This limestone, indeed, notwithstanding its apparently irregular and fragmentary character, is one of the most persistent layers that we are acquainted with, for it accompanies and characterizes the old red sandstone along nearly its whole course. In Caermarthenshire, it is particularly remarkable in the cliffs near Laugharne, from which specimens may be obtained not distinguishable from the ' goose- berry' stone of Monmouth. Comparing these enormous masses of conglomeritic arenaceous and argiUaceous rock, and this included limestone, with the older Silurian series, we find the main mineral distinction to be in the state of the iron which colours the rocks. Protoxide of iron is common in the older series, peroxide is prevalent in the newer group. As in many other cases, the gray oxide is accompanied by many, the red oxide by few remains of life. If life had been more abundant, the now irregular cornstones might have assumed the aspect of Wenlock or a 71 a SUurian conformed to, b Old Red, and c Carboniferous. Aymestry limestone. We shall find as we proceed, an exact verifi- cation of this suggestion in the Devonian type of the Middle Palae- ozoics. On the whole the older red series of Wales, and the course of the Wye and Severn, may be thus expressed in general terms : Upper Group. Conglomerates, and sandstones of red, purple, and green hue, the pebbles, scattered in layers through masses of considerable thickness, are mostly of quartz, such as occurs abundantly in veins in the mica schist and gneissose rocks. The magnitude of the pebbles varies from an inch or two across to small white grains. Holoptychius nobilissimus occurs in this series. Middle Group. Flagstone series, in great thickness, with partings of red shale and some irregular calcareous cornstones. In the country about Milford Haven this series is usually traversed by nearly vertical slaty cleavage. Cephalaspis is met with in this series. Lower Group. Marl series, mostly red, with pale and greenish bands, and irregu- lar cornstone layers. White, dark gray, and yellowish sandstones appear in the lower part of the series, especially round the Mayhill district. (There is no coarse conglomerate hi this part of the series comparable with that of the Cumbrian and Grampian chains.) 142 MIDDLE PALEOZOIC STEATA. Passing from the districts of Mayhill and the Forest of Dean to the southward, we find the same general type of the old red in the country of Tort worth, on the banks of the Avon, below Bristol,* and in the anticlinal axis of the Mendip, near Banwell. But on the reappearance of the group in North Devon, it has a different aspect and composition. North Devonian Type. We are indebted to Sir H. T. de la Bechef for the first clear view of the succession of beds in the district of North Devon. The country is greatly contorted the strata rising and falling in many steep anticlinals and deep synclinals, which run mostly from west to east. (See fig. 72.) In a survey which was made by the author 72 in 1839, he found the advantage of studying the great North Devon series in several groups as under J : Uppermost Group of Pilton. This is a series of flaggy sandstones and shales, with interrupted and nodular deposits of limestone, full of fishes, much analogous to those found in the lowest part of the mountain limestone series, (to be noticed hereafter,) with which it might without much inconvenience be classed. The group below undoubtedly belongs to the old red series. Morthoe Group. Purple and gray schistose series, with interstratified gritstones, (slaty cleavage). No fossils. Ilfracombe Group. Gray argillaceous series, with limestone bands containing corals and shells, (slaty cleavage). Martinhoe Group. Red, claret-coloured, gray, and brown grits, with schists, &c., (slaty cleavage). No fossils. Linton Group. (1,000 feet thick,) mostly gray laminated grits and shales, with many fossils distributed in the mass, and collected in partially calcareous bands, (slaty cleavage occurs). Foreland Group. Red, gray, and claret-coloured grits and shales, (with slaty cleavage). No fossils. Passing from North and South Devon, we cross wide regions of (peculiar) carboniferous rocks ; granitic and porphyritic erup- tions have much dislocated the strata, and it becomes difficult to * See on these points De la Beche in Memoirs of Geological Survey, vol. i. 1846. t Geological Report on Cornwall, Devon, and West Somerset 1839. t Palaeozoic Fossils of Devon and Cornwall 1841. NOETH DEYOINTAN TYPE. 143 draw lines of exact contemporaneity in the rocks on the opposite sides of this one county. The following, which appeared to be the best section, was written down in Plymouth Sound, 1839, dip southerly. Group of red sandstone, and shales, with gray and purple shales (traversed more or less by slaty cleavage). In the gray shales and slates, corals, encrinites, and brachiopoda, are frequent. Group of gray schists and subcalcareous beds, interstratified with what seem to be ash beds (thrown out by ancient volcanos), and recomposed traps. Fossils nearly as in the strata above. Group of limestones, abundant at Plymouth, Torquay, &c. It is quite irregular, sometimes like a huge coral reef, in other places divided by shale partings, and toward the west thinning off to subcalcareous shales. Abundance of corals, brachiopoda, gasteropoda, cephalopoda, &c. Very slight trace of fishes. Group of purple slaty rocks, some ash beds, the original lamination discoverable. No fossils yet observed. If we class, as appears most advisable, the Plymouth limestone with that of Ilfracombe, we shall find the higher beds of South Devon by no means unlike the lower beds of North Devon. On the whole, the red element is diminished, animal life more widely dif- fused. The Plymouth limestone contains many Eifel fossils, and may be regarded as typical of the Middle Palaeozoic system in Britain. We omit the as yet unfinished survey of the Devonian beds through Cornwall, where it appears that some traces of Silurian strata below them are satisfactory to Murchison.* The old red series occurs in the Island of Arran, north of Brodick Bay, conglomeritic and arenaceous, accompanied by thin red lime- stone, with the usual crinoidea and brachiopoda of the mountain limestone, and thin gritstone and shale (coal measures) accompanied by stigmaria. (See Eamsay's Guide to Arran.) In the Isle of Man, we see the same formation principally in steep cliffs north of Peel and about Castleton ; in the latter case resting on Silurian or Cambrian schists, overlaid by limestone, and traversed by trap dykes. Ireland offers what seems to be a large development of brownish old red sandstone in the district east of Lough Erne, and south of Omagh, where it is arenaceous and conglomeritic, and rests on lower Silurian and Cambrian. About Castlebar, and extending from New- port to Lough Conn in Mayo, is a large tract of brown red sand- stone and conglomerate, said to be unconformdbly below the mountain limestone. f In the central tracts of Ireland, Mr. Griffith mentions and maps old red sandstone in the elevated tracts of Slieve Bloom, * Siluria. t Griffith in Reports of British Association, 1843, p. 48. 144 MIDDLE PALAEOZOIC STRATA. the Inchiquin, Beruagh, Keeper, and Galtee mountains. Other tracts occur in the promontory of Dingle, and the vicinity of Kil- larney and Bantry. But the largest area, and probably the most certainly ascertained to belong to the old red, is that which surrounds Cork, Youghal, Dungarvan, and Waterford, everywhere covered by the lower members of the great limestone series everywhere ex- tremely similar to the old red sandstones and marls of Pembroke- shire, and like them traversed by slaty cleavage, the angle of inclina- tion of the cleavage to the plane of the strata often varying from bed to bed.* The middle Palaeozoic series, considered with reference to the two types now described, appears to have assignable geographical charac- ters. The "old red sandstone" type prevails everywhere in the British Isles north of the Bristol Channel ; the Devonian type spreads farther southward and eastward in Europe, being recognized in Brit- tany, between lower Silurian and carboniferous rocks ; in the district of Boulogne, which appears to have the upper parts of the series only, and on the E-hine and Moselle, where the whole series of North Devon appears to be almost exactly represented by parallel According to Murchison's latest view,f we may group the Khenish and Belgian type of the old red series in the following manner : Upper Devonian. A series of schists characterized very extensively by the presence of a bivalvular crustacean (cypridina), and when limestones interlaminate the schist, by goniatites and clymeniae. It prevails in Nassau, in Saxony, and Thuringia. It may be paralleled by the clvmenian limestone of Pctherwin, and the upper beds of North Devon. Eifel Limestone. The great central calcareous mass, equivalent to that of Ply- mouth, and probably to that of Ilfracombe, full of corals, crinoidea, brachio- poda, gasteropoda, cephalopoda, and trilobites, and some of the old red fishes. Stringocephalus Burtini belongs to this rock. Middle Devonian Schists, with sandstones and some lenticular limestones. Cal- ceola sandalina belongs to this group. Lower Devonian. Sandstones with slaty schists, and some impure limestone. This contains large spiriferse, some species of phacops, and the curious pleurodictyum problematicum. On the whole, the resemblance of this series to that of Devonshire is very satisfactory. Parting from the mountainous regions of the Taurus and the Hundsruck, and the streams of the Lahn, Rhine, and Moselle, we find in the old volcanic region of the Eifel, the Devonian strata much disturbed and even inverted, and this character, which is con- tinued in Belgium, has caused much difficulty to M. Dumont. * This observation was reported to the British Association Meeting in Cork, 1843. t Siluria, p. 367 NOETH DEYOKLAN TYPE. 145 Two-thirds of the area of the chain of the Pyrenees is composed of clay slate, which appears to exhibit many varieties of texture and aggregation, the coarser kinds being dark green, micaceous, or gran- ular, aluminous or siliceous. It appears to be mainly of the Devonian age. Frequently these slates alternate in very thin layers with limestone, in which case a number of calcareous fibres crossing the slate, but not the limestone, give the mass the peculiar appearance of schiste rubanne ; limestone abounds with this slate series, and is either compact, slaty, or granular, always more or less metamorphic. It contains crinoidal and zoophytic fossils, " goniatites," and a few other shells, and some are found in the alternating slates. Anthra- cite in small quantities is mixed with the slates ; quartzose, felspathic, and greenstone rocks alternate with them. Most of the metallic products of the Pyrenees are found in the slaty system. (Char- pentier.) Spain possesses in the Sierra Morena, the Asturias, Sierra Canta- brica, sandstones, shales, and limestones, red and gray, and richly fossiliferous, as Mr. Pratt and De Yerneuil have proved. In Germany, the Devonian rocks are, on the whole, more extended than the Silurian. The Hartz limestones and slates, described by M. Bonnard, Roemer, and others, appear to be of Devonian age. Devonian forms appear in calcareous rocks in the Thuringerald, Franconia, and Yoigtland. In Franconia, especially at Elbersreuth, we have Devonian limestones, with many clymenise and goniatites, comparable to those of Petherwin, near Launceston. The basin of Bohemia, with Prague for its centre, affords a com- plete Silurian series, the uppermost form offering some marked De- vonian analogies. In the Riesengebirge, south of Breslau, a Devonian limestone occurs with fossils ; the same is observable in Moravia. Near Warsaw, a small tract of Devonian rocks with fossils occur. In Russia, though not of great thickness, the Devonian beds spread very widely in a country of moderate undulation. Here we have the interesting and important fact of the occurrence together of the ichthyoid life of the old red type, Asterolepis, Grlyptosteus, Dendrodus, Holoptychius, Pterichthys, with the molluscous life of the Devonian type.* From the Valdai hills and the Baltic pro- vinces to the White Sea, these rocks offer many interesting points of study, the sandy rocks more particularly yielding fishes, the argillaceous and calcareous bands being more prolific of orthides, rhynconella, atrypse, &c. In the very lowest beds, goniatites occur. It appears to be unconfirmed to the Silurian rocks,t and to be free from Plutonic irruptions, except on the flanks of the Uralian chain. * Austen in Geological Proceedings, t Murchison, Geology of Kussia, Siluria, chap. xiv. L 146 MIDDLE PALEOZOIC STEATA. In the Strensfiord, west of Christiania, the old red sandstone has the character of conglomerate.* The upper groups of the series of New York State and Canada, given by Mr. Hall, are now generally admitted to belong to the Devonian age. They are in perfect conformity, both to the Silurian below, and to the Carboniferous rocks above. They contain many Devonian fossils. A similar succession has been recognized in South America, by D'Orbigny.f Perhaps the Falkland Isles contain such fossils. J The Cape of Good Hope yields Devonian fossils : they have been collected in Central Africa by Dr. Overweg. In Asia, the Himalaya, and perhaps most of the great chains, contain Silurian and probably Devonian representatives, and charac- teristic fossils of the latter groups have come to Europe from Ke- vangsi, south of Shanghai, and from Itier, north of Canton. Finally, Australia gave to Count Strzelecki, Devonian, as well as other Palaeozoic forms. Metallic veins are rare in the old red sand- stone rocks, but veins of crystallized earthy substances occur fre- quently. Carbonate of lime traverses it at Kirkby Lonsdale ; sulphate of barytes near Monmouth and South Sannox in Arran ; sulphate of strontian occurs in it, near Inverness : and asbestus in Kincardine- shire. (Boue\) PLANTS. FILIC IN^E . Cyclopteris Hibernicus, . 1 S th. of Ireland Actinophyllum plicatum, || 1 Woolhope district, Lepidostrobus ? || . . 1 Woolhope district, AMORPHOZOA. Scyphia turbinata, . . 1 South Devon, Steganodictyum, . . 2 Cornwall, FORAMINIFERA. Occur in the limestones of Cannington Park and South Devon. ZOOPHYTA. ZOANTHARIA. Acervularia, . . 5 South Devon, Alveolites, ... 4 Do. Amplexus, ... 1 Do. Arachnophyllum, . . 2 Do. * Murchison, Siluria, p. 319. t Voyage dens I'Amerique Maridionate, 1842. t Darwin. Bain in Geol. Proceedings. || These two plants are found at the very base of the old red, or on the very top of the Silurian. OEGAKIC EEMAINS. 147 Battersbya, 1 Do. Sth. of Ireland. C am pophyllum 1 Do. C toropli vllum 1 Do. C yathoph yll um , 8 Do. C vstiph vllutn 2 Do. Emmonsia . 1 Do. JS n dophy Hum 2 Do. Favosites, 3 /North and (South Devon, Hallia, 1 South Devon. Heliolites, 2 Do. Metriophyllum, 1 Do. Pachyphyllum, 1 Do. Petraia, . 4 (North and (South Devon, Pleurodictyuui. 1 South Devon Sarcinula, 1 Do. Smithia, 1 Do. Sponsrophyllutn, 1 Do. ^F^ o r J * Ai * Lli j Strephodes, 3 Do. Stromatopora (Caunopora) 5 Do. ECHINODERMAT. /L CKINOIDEA. Actinocrinus, 1 South Devon. Adelocrinus, . 1 Brushford,ND. Cupressocrinus, 1 South Devon. Cyathocrinus, 8 4 S. Devon, 4 N. Devon. Hexacrinus, 3 South Devon. Taxocrinus, , . . 1 North Devon. BLASTOIDEA. Pentremites, 1 North Devon. CTSTOIDEA. Echinosphaerites, 1 South Devon. ARTICULATA. ANNELIDA. Tentaculites, . 1 /South Devon, \ (Salter). CRUSTACEA. Bronteus, 1 South Devon. Cheimrus, . . : . 1 South Devon. Harpes, 1 South Devon. Homalonotus, 1 Do. Calymene, . . . .-, . 4 2 So. Devon, /I Petherwin, \1 Croyde, &c. Phillipsia, . . . 1 South Devon. Trimerocephalus, 1 South Devon. Cypridina, 1 Petherwin* Pterygotus, . 1 Forfarshire. 148 MIDDLE PALEOZOIC STKATA. Ceriopora, Fenestella, Glauconome, Hemitrypa, Ptilopora, Retepora, 3 So. Devon, Barton, S.D. ( Plymouth. (Barton. MaidstoneBay. (Pilton, (Brushford. 1 Petherwin. Croyde, Pilton. BRACHIOPODA. Athyris, Atrypa, Calceola, Chonetes, Cyrtia, Leptaena ? Orthis, Pentamerus, Producta, Retzia, Rhynconella, Spirifera, Strophalosia, Terebratula, 4 1 4 1 8 12 3 4 1 19 27 2 3 f Merton, Ogwell"! \ Sft'St }>* ^ ten, Torquay J South Devon, Petherwin. South Devon. o it. -rk fLinton, South Devon, { ,, , ,,' , ' \Brushford. South Devon. (South Devon. (Cornwall. South Devon, South Devon. Plymouth, South Devon, South Devon, Pilton, Brushf. Crode. South Devon, {^^on. Plymouth, Petherwin, &c. South Devon. Avicula, Aviculopecten, Pterinea, MONOMYARIA. 1 So. Devon, /4 Petherwin, lj \ Polter, &c. 1 So. Devon, 7 No. Devon. 1 So. Devon, 2 No. Devon. DIMYARIA. Anodonta ? Axinus, Cleidophorus, Conocardium, Corbula, Cucullsea, Cyclas, Cypricardia, Leptodmus, Megalodon, Modiola, 1 Torquay. South Devon. South Devon. Scotland. South Devon. South Devon, 1 Ireland. 1 No. Devon. North Devon. North Devon. North Devon. Petherwin. OBGAHTC BEMAINS. 149 Mytilus, Nucula, Pullastra? Sanguinolaria ? Sanguinolites, South Devon. North Devon. South Devon, North Devon. ("North Devon, \Cambria, &c. North Devon. GASTEROPODA. Capulus, Euomphalus, . Loxonema, Macrocheilus, Murchisonia, . Natica, Nerita, Pleurotomaria, Turbo, South Devon. 4 So. Devon, Newt. Bartn. South Devon, South Devon, South Devon. South Devon, South Devon. 1 N. Devon. Petherwin. 1 N. Devon. Peth. Brushf. N. Dev., &c. North Devon. Bellerophon, Porcellia, HETEROPODA. South Devon, North Devon. Petherw., &c. CEPHALOPODA. Clymenia, Cyrtoceras, Goniatites, Nautilus, Orthoceras, 11 13 9 2 10 South Devon, North Devon. South Devon, North Devon. South Devon, Petherwin. South Devon, N. Devon, &c. Acanthodes, Actinolepis, Asterolepis, Bothriolepis, . Byssacanthus, Cephalaspis, . Cheiracanthus, Cheirolepis, . Climatius, Coccosteus, Conchodus, Cosmacanthus, Ctenacanthus, Ctenoptychius, Dendrodus, Diplocanthus, Diplopterus, Dipterus, Glyptolepis, . Glyptopomus, Gyroptychius, FISHES. 1 Elgin, Gordon Castle. 1 Elgin. 3 Elgin, Caithness. 2 Elgin, Nairn. 1 Herefordshire. 4 Herefordshire, Forfarshire. 5 Orkney, Gamrie, &c. 6 Orkney, Cromarty. 1 Balruddery. 7 Orkney, Cromarty. 1 Scat Craig. 1 Elgin. 1 Abergavenny. 1 Scotland. 4 Morayshire. 6 Morayshire, Orkney. 4 Orkney, Caithness, Gamrie. 1 Orkney, Caithness. 3 Elgin, Gamrie. 1 Perthshire. 2 Orkney. 150 MIDDLE PALEOZOIC STKATA. Holoptychius, Homothorax, Lamnodus, Onchus, Osteolepis, Pamphractus, Parexus, Phyllolepis, Placothorax r Platygnathus, Pterichthys, Ptycacanthus, Stagonolepis, Tripterus, Telerpeton Elginense, 7 Orkney, Elgin, Perthsh., Brecon. 1 Perthshire. 3 Elgin. 2 Herefordshire. 5 Orkney, Caithness. 1 Perthshire. 1 Balruddery. 1 Clashbinnie. 1 Elgin. 2 Orkney, Perthshire. 10 Orkney, Cromarty, Gamrie. 2 Herefordshire, Monmouthshire. 1 Elgin. 1 Orkney. REPTILIA. 1 Elgin, Analyzing the middle Palaeozoic groups of life on the same plan as that used for the Silurian, we have the following proportions to 1000. Plants, Amorphozoa ? Foraminifera, Zoophyta, Echinodermata, Annelida, Cirripedia, Crustacea, Insecta, Tunicata, Prop, to 1000. 7 Bryozoa, 7 Brachiopoda, . . . 2 Monomyaria, .123 Dimyaria, > , 40 Gasteropoda, ; . 2 Cephalopoda, ..* . o Fishes, ; * . 28 Reptilia, Aves, Mammalia, Prop, to 1000. . 22 . 225* . 40 . 71 . 104 . 106 . 221* 2 NOTE. Comparing this with the tables for the Lower Palasozoic^strata, we perceive the same general abundance of zoophyta, brachiopoda, gasteropoda, and cephalopoda ; but the Crustacea which had begun to diminish in upper Silurians are here still more reduced ; fishes, which in those deposits were few, are here extremely numerous, and reptiles for the first tune come into notice. The brachiopoda still retain then: abso- lute numerical superiority. (See for comparison, page 128.) FOSSILS. MIDDLE PALAEOZOIC FOSSILS. 151 76a 73 Arachnophyllum Hennahii, natural surface. 74 Variety of the same cut across. 75 Cystiphyllum vesiculosum, cut to show the structure. 76 Heliolites pyriformis. 76a Magnified section. 152 MIDDLE PALEOZOIC FOSSILS. 79 78a 79a 77 Hemitrypa oculata. a Small specimen. 6 External face of a magnified, c Centre of a large specimen. d External face of c. e Internal face of c. 78 Stromatopora polymorpha. 78a Magnified section. 79 Hexacrinus interscapularis 79a The apex. MIDDLE PALEOZOIC FOSSILS. 153 80 Calceola sandalina. ' 81 Producta caperata. 82 Rhynconella cuboides. 83 ^pirifera gigantea. 84 Striiigocephalus Burtiui. 154 MIDDLE PALEOZOIC FOSSILS. 85 Avicula spinosa. 86 Cucullsea ? trapezium. 87 Murchisonia spinosu. 88a Pleurotomaria aspera (6) magnified. 88c Pleurotomaria aspera, variety d magnified. 89 Cyrtoceras tredecimale. MIDDLE PALEOZOIC FOSSILS. 155 1)0 90 Clymenia tevigata. (a) Cross section. (6) Edge of a septum. 156 MIDDLE PALAEOZOIC FOSSILS. 91 Goniatites insignis. (6) Edge of a septum. 92 Cephalaspis Lyellii. 93 Pterichthys Milleri. CAEBONIFEBOT7S SYSTEM. 157 CHAPTEE VIII. UPPER PALEOZOIC STBATA. Carboniferous System. Divisions of the System. In England the carboniferous system, when fully expanded, admits of division into the following groups, which, however, are not to be found together in every district : e. Coal formation (upper group). d. Millstone grit (supramedial group), c. Yoredale Rocks (medial group). b. Scar limestone (submedial group), a. Shales, &c. (lower group). The five groups here admitted easily and naturally collect them- selves into two greater assemblages, the upper one specially carboni- ferous, the lower one specially calcareous, but in each of the many districts of Britain where these valuable strata occur, some local peculiarity is observable which often disturbs the classification. The millstone grit connects itself by marine fossils with the Yoredale rocks in the north of England, and with the coal measures by its plants, and thus has the air of a transition group, which may for convenience be sometimes joined to the lower, sometimes to the upper series, and occasionally be treated alone, and the lowest mem- ber, in some places calcareous, in others argillaceous, or arenaceous, varies much in its affinities to the limestone. It has sometimes been referred to the red sandstone series below. In Yorkshire, the limestone series begins to be intermingled with coal, sandstones, and shales ; in the northern parts of Northumberland these two series are intimately blended. The millstone grit is 800 feet thick in Yorkshire and Derbyshire, but dwindles away to a mere band in many parts of the south of England. There is nothing peculiar in this : we shall find exactly similar phenomena among the superior formations. In fact, it is certain that among all the formations, the minute distinctions of strata are mostly local, and even the formations themselves, however extensive, are limited within the circuit of the anciently elevated mountains. The whole series is in Britain conformable to the red sandstone below, and was united to that rock by Mr. Conybeare.* In describing this series, we shall confine ourselves principally to the British Isles. * Geology of England and Wales. 158 UPPEE PALAEOZOIC STEATA. Carboniferous System Its Geographical distribution in England and Wales. Passing over the anticlinal ridges of the Lammermuirs, we come to the great connected carboniferous system of Tweeddale, Northum- berland, Durham, Yorkshire, Derbyshire, and Nottinghamshire, which spreads westward to Cheshire, and Lancashire, Westmoreland, Cumberland, and Dumfriesshire ; a district 200 miles in length and on the average 60 miles in breadth. Berwick, Kelso, Langholm, Ecclefechan, Brampton, Brough, Shap, Cockermouth, Whitehaven, Dent, Kendal, Ulverstone, Lancaster, Preston, Liverpool, Manches- ter, Newcastle-under-Lyne, Cheadle, Nottingham, Bolsover, Conis- borough, Aberford, Kipon, Eichmond, Ferryhill, and Tynemouth may be noted as on or near to the border of this great field. In it all the five divisions already stated may be recognized. A long but narrow and broken band of the carboniferous system is traced from Anglesea, by the Orme's Head, the sides of the Yale of Clwyd, and the country of Halkin, Mold, Wrexham, to Oswestry, and from hence we may pass by the detached coal fields of Shrews- bury, Coalbrook Dale, Billingsley, the Clee Hills, Dudley, Coventry, to the Ashby de la Zouch field, which is not far distant from Not- tingham, on the great northern run of coal. These coal fields ap- pear now separated at the surface by new red sandstone, but they may be, and probably will be, hereafter in some degree connected by subterranean operations, by perforations through the new red, of which Lord Dartmouth's trial near Birmingham is a successful pre- cursor. In none of these districts is the series of rocks so thick or so varied as in the larger tract to the north. The fullest develop- ment is in Flintshire, where limestone (6) is succeeded by a repre- sentation of millstone grit (d), and the coal series (e). This may be seen again in less compass in the Clee Hills. Farther south we have the great range of carboniferous rocks in South Wales, extending about 90 miles from St. Bride's Bay in the west, to Pontypool in the east, but interrupted by old red sandstone (on which the whole rests), at the mouth of the Towy. The breadth, at a maximum, is about 20 miles. The series consists of the following parts in the extreme west of the district : e Coal measures, . . . 11,000 feet thick! d Millstone grit, . . . 300 feet. c? b Scar limestone, * . . . 1,900 feet. a Lower shales, &c.,* . . ^ . 500 to 800 feet. Separated by old red sandstone, about 20 miles, we have the coal * I recall with much pleasure the measuring of this and many other sections in South Wales, with H. T. De la Beche, in 1841. CABBONIFEKOTJS LIMESTONE FOBMATION. 159 field of Dean Forest resting on carboniferous limestone. The series has the same terms as that of South Wales, but is not so thick in any part. e Coal, 270 146 480 165 Similar remarks apply to the small coal tract of Newent, and the more considerable field of Kingswood, both in Gloucestershire, the latter area continued across the Avon into Somerset. The section at Bristol following the Avon gives us the following general terms : e Coal, d Millstone grit, . . . 950 feet. c? ... 400 ... 6? Carboniferous limestone, . . 1438 ... a Lower shales, &c., . . . 500 ... We can give no accurately measured section of the peculiar car- boniferous system of Devon, where in general terms we have most frequently, "\ Culm and sandstones. Thick shales and thin dark limestones. The district stretches from east to west 50, and from north to south 35 miles, occupying on the whole a great broad, much undu- lated and contorted synclinal. Carboniferous System of England. The carboniferous limestone series (and millstone grit where the association is useful to the description) . Mountain or Carboniferous Limestone Formation. The carboniferous limestone is a rock of which the history must principally be studied within the limits of the British Islands, for it is nowhere else so much or so variously developed. Its romantic rocks border many of the most beautiful valleys of the south-west of Scotland, northern and central England, and encircle the wide primary regions of Wales. In Ireland, as Mr. Weaver observed, this limestone is the prevalent and characteristic rock in most of the counties, except Derry, Antrim, and Wicklow. (See Griffith's Map.) The romantic channel of the Meuse runs for a considerable dis- 160 TIPPER PALJ20ZOIC STEATA. tance about Namur and Liege, in a very remarkable range of car- boniferous limestone, along the northern side of the primary slates of the Ardennes, and is prolonged eastward to the German side of the Rhine, near Dusseldorf, and continued westward (beneath a wide deposit of chalk) to the neighbourhood of Boulogne. The coal de- posits of Poland are based upon dark limestones of the same age as the carboniferous limestone of England, but in general the coal fields of the centre anjl south of France, of Saarbruck, of Saxony, Silesia, &c., appear to be devoid of this rock ; but Murchison mentions its occurrence in the north-east of Bavaria and in Bohemia. It abounds in North America, supporting coal and anthracite. It has been before remarked, that the carboniferous limestone pre- sents itself with a very different aspect in the northern and southern counties of England. In Somersetshire, Gloucestershire, Shropshire, South Wales, North Wales, Derbyshire, and Leicestershire, this rock appears an immense, nearly undivided, calcareous mass, perfectly de- fined below by a hard contrast with the old red sandstones or Silu- rian strata which support it, and as distinct above by the abrupt covering of sandstones and shales which accompany the coal. Very rarely indeed in the southern counties, as in the eastern edge of the Forest of Dean, are any beds of sandstone interpolated among the lowest strata of limestone ; and it is only by a few unimportant partings of shale that the upper portion is at all assimilated to the incumbent series. The toadstones which irregularly interlaminate the thick limestones of Derbyshire are of igneous origin, and it is not, in proceeding northward, till we arrive in the valley of the Eibble, that any decided alternation of mechanical deposits breaks into distinct groups the strata of carboniferous limestone. From this point northward, almost in the ratio of distance, to the banks of the Tweed, the limestone becomes more and more divided by beds of sandstone and shale, accompanied by ironstone, fossil plants, and coal ; and thus, under Ingleborough we have a nearly undivided cal- careous mass 400 or 500 feet thick ; but at Aldstone Moor no less than twenty different limestones, amounting altogether to 470 feet, obscured by the interposition of no less than 1,686 feet of sediment- ary strata. Farther north these mechanical admixtures increase in amount, while the calcareous strata diminish, and at length, in the northern parts of Northumberland, the limestone district has become a valu- able coal field. To embrace the subject in its most interesting point of view, we shall commence our account of the carboniferous limestone with a description of its characters in the " Penine Alps," which border the western parts of Yorkshire and Durham, and the eastern parts of Cumberland and Westmoreland, and we shall connect therewith DISLOCATED CARBONIFEROUS LIMESTONE. 161 the analogous arches of limestone, which begird the primary district of the Cumbrian lakes. Taking this as a type of the formation, we shall be able to compare with it the other localities in the British Isles and on the continent of Europe. This tract of country has been, for different objects, partially de- scribed by Professor Sedgwick and other geologists, and their views, whether published or not, will be recognized in the following sum- mary. The Cumbrian slates are surrounded for three quarters of a circle, from Egremont to Ulverston, by a belt of limestone, which reposes indiscriminately upon the lower slate near Loweswater, the middle slates near Ulswater, the upper slates from Shap to Ulverston, and the old red conglomerate at the several points of Dacre, Sed- bergh, Barbon, Kirkby Lonsdale, and Ulverston The south-eastern part of this circular belt forms part of a long range of limestone cliffs facing the west from Ingleborough to Tindal Fell, defined by one continuous line of elevation nearly 1,000 yards in height. Prodigious transverse dislocations occur at these points ; that at the northern end ranges east and west, and causes an im- mense depression to the north, after which the limestones range north-east through Northumberland ; that at the southern end ranges west-south-west and east-south-east, and causes an equally striking depression to the south, after which the limestones show themselves locally, and in much disturbance, as far south as Clithero. 94 Dislocated limestones at the edge of the Pennine chain. 6 Scar limestones on the east. * Silurian on the west. From the high western escarpment before mentioned, the strata sink with a very regular inclination eastward or south-eastward, and are exposed in the valleys of the South Tyne, Derwent, Wear, Tees, Greta, Swale, Yore, Ribble, Wharfe, Nid, and Aire, bordering those streams with some of the boldest and most picturesque rock scenery in England. The grand natural section of Ingleborough and Penyghent pre- sents us with the following series of rocks belonging to the carboni- ferous formations, to which letters are affixed in the order already assigned : Vtone.... ...lMain N > 78 Feet. 200 162 TTPPEE PALEOZOIC STEATA. Feet. d Group above the lime-~] Alternations of sandstone and shale, with bad stone, commonly! coal on Penyghent 100 called millstone grit ( Millstone grit of In gleborough 60 series J Alternations of sandstone and shale 100 t Thin limestone 8 feet "| Shale 10 Main ") ,. ~ .> limestone... 60 Great/ ^Alternations principally of shales and sandstones, some of them flag- stones, with thin limestones, 300 b Great scar limestones with calcareous conglomerate beds at bottom 400 This series rests on slate rocks (Lower Silurian). Proceeding northward from Ingleborough we arrive in Wensley- dale or Yoredale, and find the section modified as under : f Coarse and fine sandstones, shales, and COAL Millstone grit series. I Coarse ' fine ' and slaty sandstones > shales > Cnert 7 ct Above the limestone, i **,-, ' -r"", /'"i"i Millstone grit of Ingleborough, shales, cherts, and L COAL (Thin limestone, sandstone, shale. f Upper limestone belt. < Main or twelve fathom limestone (Shales, sandstones, and COAL, underset limestone., f Alternations of flagstones of various quality, inl great abundance, with shales, COAL, hard grit- | Flagstone series \ stones, and three or four strata of limestone, V 500 from 6 to 30 feet thick. The black marble of | (^ Dent is nearly a t the base of this group J b Scar limestones /Limestones of 'great thickness, with partings prin-) \ cipally of shale > The series is incomplete, other limestones existing below. Here it will be perceived the group d has become divided into dis- tinct parts ; and the calcareous portions of c are also more defined and more important } the upper part, >, has assumed that character of a decidedly double belt, which henceforward distinguishes it for a great distance to the northward. Our next station will be taken in Swaledale. f Coarse gritstones, shales, finer sandstones,) Q Feet. j shales, and COAL > ) d Millstone grit series.. \ Variable series of thick shales, with sand-S r 800 | stones and COAL, and local interpolations > 200 ) I of limestone and chert ) Limestone 3^1 Shale, &c 63 Main or twelve fathom lime 72 > 252 Grit, chert, shale, and COAL 96 [ Underset lime 1 8 J Variable alternations of gritstone, flagstone, and) f Upper limestone belt. [_ Flagstone series plate, with three or four limestones from 6 to 30- 340 feet thick , J Scar limestones ? Of great thickness, but only partially exposed in S I the bottom of Swaledale j FOESTEE'S MINING SECTION. 163 The groups c and d have now become more complicated, and re- quire further division as compared with the Ingleborough section, and thus we are gradually conducted to the still more developed series of Teesdale and Aldstone Moor, as described by Forster : Mm- r rm P o*ri f. I stone grit f Upper limestone belt. L Flag- stone system. Scar lime- stones. Calcareous Other de- beds, posits, yds. ft. in. yds. ft. in. Alternations of sandstone (coarse and fine), and shale 25 1 1. FeUtoplime 116 Alternations of laminated and other sand- stones, shales, ironstone, and COAL... 109 2 8 2. Limestone 300 Alternations, plate, &c., with COAL 16 2 Limestone 21 3. Parting 10 4. Limestone 016 Sandstone, and shale, and COAL 5. Underset limestone 800 Sandstone and shale (Nattriss Gill Hazle) 6. Limestone 300 Sandstone and shale '. 7. Limestone (5 yards) 216 Sandstone and shale 8. Scar limestone 10 Thin alternations 9. Cockleshell limestone 020 Alternations 10. Limestone (single post) 200 Alternations.... 2)5 17 1 15 1 6 10 15 526 20 11. Tyne bottom limestone 800 Alternations in the upper part of which the " Whin sill " (igneous) occurs, (20 to 40 yards thick) 24 2 6 12. Jew lime 800 Alternations 826 13. Little lime 600 Alternations, 30 14. Smiddy lime 10 1 6 Sandstone, 15. Limestone 816 Alternations 16. Robinson's lime 700 Alternations 17. Great limestone, Melmerby scar 44 Alternations and COAL ; 18. Limestone 400 Alternations 55 19. Limestone 216 Alternations and COAL 73 2 20. Limestones 600 Alternations 78 156 2 562 2 400 706 400 800 164 UPPER PALEOZOIC STRATA. It is probable that even this section does not show us the full depth of the series. 05 High Force, Teesdale. A waterfall in prismatic " whin sill " over limestone. 96 Caldron Snout, Teesdale. A waterfall in subprismatic whin sill. SECTION IN THE NOETHEEN DALES. 165 We were some time occupied in endeavours to ascertain exactly the line which in the Aldstone section separates the groups b and c of Yorkshire, and the above result is very near the truth. Combining together the preceding statements, we have the fol- lowing results in total thickness ; the sign + signifies that the thick- ness is incomplete : Group. Penyghent. Wensleydale. Swaledale. Aldstone Moor. d Millstone grit series (incomplete series). 260-(- 700 800 409 f Upper limestone belt. 80 200 250 247 c -(Alternations, or flag- ( stone system 300 400 250 304 b Scar limestones 400 250+ 120+ 1196 In the following table the relative proportions of the calcareous and other deposits are estimated : a Penyghent. Wensleydale. Swaledale. Aldstone Moor. o Lime- Other de- Lime- Other de- Lime- Other de- Lime- Other de- stones. posits. stones. posits. stones. posits. stones. posirs. d j> 260 p 700 10 790 4 405 f 70 10 100 100 93 157 97 150 C ( 30 270 50 350 40 210 54 250 b 400 150+ -100 80+ - 40 313 883 500 540 300+ 1250+ 223+ 1197+ 468 1688 We must remark that this comparison is imperfect, because the sections are not in each case defined above or below by the same beds ; in order to obtain a fairer numerical comparison, we may omit altogether the beds above the upper limestone belt, and, on account of its incompleteness, the fourth group in Wensleydale and Swale- dale. We shall then have the following corrected scale : Penyghent. Wensleydale. Swaledale. Aldstone Moor. Lime- Other de> Lime- Other de- Lime- Other de- Lime- Other de- stones, posits, stones, posits, stones, posits, stones, posits. Upper limestone belt.... 70 10 100 100 93 157 97 150 Flagstone series 30 270 50 350 40 210) 54 250 Scar limestones 400 / 313 883 500 280 464 1283 Had we, instead of Penyghent, chosen Great Whernside for our section, we should have had the limestone of these groups about 1,000 feet, and the other deposits less than 200 feet : and if we had taken a section in Northumberland, instead of Aldstone Moor, the lime- stones would have been less than 200 feet, and the other deposits probably nearer 1,000 feet. The principal changes, as we proceed northward, appear to happen in the lower part of the limestone group, which loses its individuality, by admitting between its beds a constantly increasing quantity of mechanical admixtures, and at 166 UPPEE PALAEOZOIC STEATA. length becomes a subordinate feature in a country which has the characters of a coal field. We shall now trace the course of the car- boniferous limestone round the Cumbrian mountains, and through other parts of England. Range of the Mountain limestone. The submedial, or as we also name it "scar limestone" group, passes westward from Ingleborough by Kirkby Lonsdale, Burton, and Cartmell to Ulverstone and Dalton ; extending northward to Kendal. (See Smith, Geological County Maps.) This group everywhere possesses the almost wholly calca- reous character which it bears in Ingleborough. On the south of Ulverstone, it is covered by the intermediate grit and plate series, with traces of coal, and a more extensive deposit of this kind south of Kirkby Lonsdale, yielding useful coal and flagstone, is again over- laid by the upper belt of limestone and afterwards by the millstone grit series towards Lancaster. 97 Gordale Scar, near Settle. In scar limestone. Under Wild Boar Fell, on the borders of Yorkshire and West- moreland, the scar limestones begin to exhibit, in consequence of dis- locations, a double escarpment, the western branch passes off by CABBONLEEKOUS LIMESTONE NORTH OF ENGLAND. 167 Ashfell, Orton, Shap, and Lowther, to the Eamont, and continues by Grey stoke Park, Hesket, Ireby, and Cockermouth to Egremont. These limestones alternate in their lower parts with red sandstone, by some geologists referred to the old red, and diminish in thickness westward. These alternations are referred to the lower group (a). They are overlaid by deposits of the grit and shale series near Shap, Hesket, Newmarket, and Bolton, but from Workington to White- haven the thick and abundant coal seams probably belong to the ordinary coal series (e) above the millstone grit. There is perhaps unconformity here between the coal measures and the limestone, a case very rarely observed in England. Agreeably to what has been said before, the scar limestones, in passing through Northumberland, become continually more and more subdivided by interpolations of sandstone, shale, and coal, till on the sea-coast north of Belford, a part of this series contains no less than thirteen bands of limestone, (121 feet in total thickness,) separated by many times their thickness of sandstone and shale, and under the whole lie workable seams of coal. The .character of the surface of all the western and north-western part of Northumberland corresponds to this change of the component strata. Instead of the beautiful green pastures which delight our eyes amidst the calcareous dales of Derbyshire and Yorkshire, wide, heathy, and boggy moorlands overspread the surface of sandstones and shales, and we seem to wander in a region of barren coal measures rather than on the range of the thickest carboniferous limestones. This may serve to explain the seeming anomaly in Mr. Greenough's map, where this unquestionably carboniferous tract was formerly represented as distinct from any of the strata in the British section. Mr. Smith coloured the whole space as a coal tract. On the contrary, in proceeding southward along the Kibble, we find the scar limestones in great force about Clithero, surmounted by a considerable mass of shales and sandstones, corresponding to the shale and grit series of Ingleborough ; above these, in Pendle Hill, appears the diminished upper belt of limestone, and, over ah 1 , the millstone grit series, here also occasionally yielding coal. Hence to Derbyshire the scar limestones lie too deep to be seen, and the upper belt of limestone appears to be extinguished ; so that this part of the western boundary of Yorkshire is occupied by a vast thickness of the millstone grit series and the medial flagstone series, without any disclosure of the sub- jacent limestones, even in the deeply excavated valley of Todmorden. In Derbyshire, putting out of the question the irregular interpo- lations of igneous rocks, called toadstone, we have the scar limestones more than 750 feet thick, surmounted by shale, with their alternations of sandstone, limestone, ironstone, &c., 500 feet, and the hills are crowned by bold ranges of millstone grit, and its accompanying sandstones, 360 feet in thickness. 168 UPPER PALEOZOIC STRATA. See fig. 98, which expresses in general terms the method of variation of the carboniferous limestone and millstone grit series of the grand Pennine chain. Section of the lower and middle parts of the Carboniferous system in the Pennine chain. d Millstone grit. c Yoredale series. 6 Scar limestone. 5 Silurian. South of Derbyshire we have no longer the same remarkable masses of strata (c, d) interposed between the scar limestones and, the pro- per carboniferous sandstones and shales. The limestone occurs in North Wales, as in Anglesea, across the centre and on the northern coast, about Beaumaris, and on the Menai Strait. It forms the con- spicuous promontory of Orme's Head, runs under Denbigh and Ruthin on the western side of the vale of Clwyd, shows in limited and disturbed patches on the east of that vale, forms the picturesque and elevated country west of Holywell, Mold, and Wrexham, turns round the magnificent cliffs of Eglwyseg to overlook the beautiful Vale of Llangollen, and continues its course southward to an almost sudden termination at Llanymynach, near Oswestry. In this range there is only a narrow trace of old red sandstone below it, as in the cliffs of Eglwyseg. This whole range represents the scar limestone or submedial group of the system (6). Slightly exhibited under the coal of the Glee Hills, it resumes its grandeur on the edge of the Forest of Dean, and there discloses, from beneath, the lower group (a) in sections above Mitchell Dean, as well as the supermedial group {d) all round the forest. De la Beche* has given the materials for the short summary which follows : e Coal above all. d Millstone grit, consisting of sandstone, shale, and conglomerate. {Gray and red limestones and marls 25 feet"] c Medial band < Red sandstone, with thin shales and marls, ( some haematite veins 176 b Scar limestone, red, gray, and blue, with haematite 480 a Lower group of shales and limestones, mostly dark, with remains of fishes 165 * Memoirs of Geological Survey, vol. i., p. 127. 201 feet. CABBOtflFEBOUS LIMESTONE WALES. 169 The upper part of the old red series, containing gray, yellow, and red sandstones and marls, with scatterings of quartz pebbles, &c. Plants analogous to some in North Devon occur in this series. On the Avon it is thicker. Round a great part of the South Wales coal field, we find the lower series (a) rising to importance, and con- tinually thickening to the westward; so that, in the district of Grower, a part of Pembrokeshire, its thick shales and thin limestones constitute great cliffs and scars, full of fossils having analogies to those of the Upper Devonian series. In Ireland, especially in the southern parts, this analogy is still more apparent and extensive. The limestone tract along the Meuse is evidently of the same era as the limestone of Derbyshire and Monmouthshire, and continually recalls to the delighted voyager the beauties of the Derwent and the Wye, but the strata above it are with difficulty compared in detail with those of any part of the English basins. In still greater thickness we find the carboniferous limestone groups pass round the " basin " of the South Wales coal field, under " millstone grit," and over the old red sandstone. At the western extremity of the range, and on the south side (West Angle Bay), we find by the measures of the Geological Survey, 1841, the lower series of shales, limestones, and sandstones reddish and yellowish, in many alternations, 584 feet thick. The whole group is marked at frequent intervals by beds of coprolites and fish remains, and al- most at the bottom are remains of plants. In Caldy Island, also on the south side of the "basin," the scar limestone (6), the lower shales and old red sandstone appear in magnificent cliffs, and disclose the whole series of life, and mechanical and chemico-vital deposits. The scar limestone almost unmixed with any sedimentary matter is 1,895 feet thick, the lower beds from 400 or 500 feet, being literally full of crinoidea and strophomenae, and the upper 1,400 or 1,500 feet, yielding, besides other fossils, distinct coral bands. The lower series (a) is here about 400 feet thick, and as in the previous example, very rich in fish remains, crinoidea, strophomense, and spiriferse.* If we now add to these sections the known thicknesses of the super- incumbent strata corresponding to the millstone grit and coal mea- sures, we shall have the following general section of the carboniferous system in South Wales : e Coal formation no limestone (plants) 11,000 feet. d Millstone grit (called Farewell Rock), &c. (plants) 300 c Yoreclale rock ? (Gower shales). b Scar limestones (corals, &c.) 1,900 a Lower shales, limestones (fish beds, &c.) (a few plants) 400 14,000 Or more than two and a-half miles in thickness. * De la Beche in Memoirs of the Geological Survey, vol. L 170 UPPEE PALJEOZOIC STEATA. The thickness here assigned, however, is not attained by any one member of the group in all parts of the basin or its borders. The limestone series (a, b) in particular, is reduced to far smaller thickness in the north side of the basin, and as a whole, the series grows thinner toward the east. Perhaps it is thickest in almost all particulars about Swansea, and in the picturesque district of Grower, where in a limited tract, the Yoredale shales (c) appear to have a thickness of 1,600 feet ! * The section of lower carboniferous strata on the Avon, near Bris- tol, has been long known as the best in the south of England, and has been often copied and described, and more than once measured. The most detailed account of the thicknesses is contained in the Geological Survey's Memoirs.f In general terms it may be thus collected : d Millstone grit here mostly a hard reddish gritstone, the grain often almost confluent as in what are called quartzites and quartz rocks 950 feet. c Alternations of limestone, red or gray, compact or granular, with shales, red, dark, or gray, and sandstones, red or gray. Fos- sils through a great part of the mass. Producta gigantea abundant near the base about 400 6 Scar limestones gray, reddish, mottled, brown and black, com- pact, shelly, crinoidal, and oolitic, in beds varying in thick- ness, and partially divided by shales 1,438 a Lower series, enclosing many alternations of limestones and shales, the former often black, brown, yellowish, sometimes impure, and in one part charged with fish remains and cyprides in abundance (" the bone bed") 500 The upper part of the old red series shows yellow and gray sand- stones and marls. Proceeding southward from the Bristol district, we may notice the sections of the limestone series in Mendip, raised on an anticlinal axis, which displays the old red sandstone. The upper part of the series not being well seen, we have the following general view : b Scar limestone, in many parts very cherty, the chert being in nodules of irregu- lar forms, and lying in the midst of the beds of limestone, which have various colours, and are, as at Bristol, often oolitic. Corals often cherty. Haematite occurs as in the limestone of Bristol and Dean Forest. a Lower series of shales with thin limestones. Thus, from the Tweed and the mountains of Northumberland, to the precipices of the Avon arid Mendip, we have traced the course of the five-parted carboniferous system, and have acquired a knowledge of the much varying bed of the sea in that large space. South of the Mendips we enter a quite different local series of these beds, * De la Beche. Mem. of Geol. Survey, vol. i. fVol. i., p. 113. CAEBONLFEROUS LIMESTONE DEYONSHIEE. 171 with little coal, and little limestone ; a series as unlike the great car- boniferous groups of the other side of the Bristol Channel as is the old red sandstone of Devon from the old red of Breconshire and Scotland. The series of carboniferous deposits in North Devon has the following general aspect about Barnstaple and Bampton (no slaty cleavage) : e, d Upper part, anthracitiferous, and containing ironstone, and by these charac- ters agreeing with the coal deposits of Pembrokeshire. This is in general a gritstone series, with plants of the coal formation. c ? Coddon Hill cherts, black, and shales of considerable but variable thickness. b Limestone and black shale, with posidoniae, goniatites, &c. a Black shale group. Similar in general character is the series of South Devon strata about Trescott and Lew Trenchard : d The gritstone group of Central Devon. c ? Upper shale group dark shales, carbonaceous grits and shales, equal to the Coddon Hill series. * b Calcareous group limestone of dark colour, and irregular bedding with shales. (Posidoniae). a Lower shale group, with few fossils. (No slaty cleavage). It appears then, on the whole, that the main conditions of the five divisions of the carboniferous system tfan still be recognized in the at first view anomalous groups of Devonshire, their special analogy pointing clearly to the extreme west of South Wales, where, as in Devonshire, the old red series is subject to slaty cleavage, and in one part, about Haverford-west, the diminished limestone is barely recognizable. Having thus compared in the most general point of view the com- ponent groups of the carboniferous limestone and millstone grit series in different localities, and ascertained the method of variation which they observe, we shall endeavour to describe some of the principal characters of these several groups. Scar Limestones. The carboniferous limestone, though by no means of one uniform aspect or chemical composition, possesses, nevertheless, a certain range of mineralogical characters which are scarcely to be recognized in any of the other secondary calcareous deposits. It is usually a nearly pure carbonate of lime, of a grayish or even very blue tint, of considerable hardness, and imperfect conchoidal fracture. Some of the varieties are very dark coloured, and even quite black (Swansea, Abergavenny, Kilkenny, Derbyshire, Yorkshire), but the latter com- monly contain a minute admixture of argillaceous and bituminous 172 T7PPEB PALEOZOIC STKATA. matter. Many varieties exhale a fetid odour on being rubbed or bruised. In Derbyshire, and generally along the Yorkshire and Westmoreland ranges, the scar limestones contain considerable beds of a granular and even brecciated limestone capable of being em- ployed as good freestone, and some layers in Derbyshire and West- moreland appear almost wholly composed of crystalline grains, and contain magnesia. A crystalline variety in Derbyshire is mixed with red oxide of iron. In the country about Burton in Kendal, and Clifton, near Bristol, the stone is often decidedly oolitic, and even exhibits considerable variety in this respect. The lower layers which rest upon the slate in the Craven mountains, at Kendal, and near Penrith, are filled with large and small boulders of the slate, so as to become a real conglomerate. But the most decided characters of these rocks are the organic remains, all of which are different from those of the strata above. The prodigious abundance of productse, spiriferse, terebratulse, and other shells, of lamellated corals, and above all, of crinoidal remains, will almost always enable even the tyro to pronounce on the identity of the mountain limestone. Crinoidal remains, in particular, are so excessively abundant in certain parts as to constitute fully three- fourths of the mass of the rock. Chert Beds and Nodules. A remarkable character is imparted to vertical sections of this rock in the Mendip hills, in several parts of Derbyshire, and the neighbourhood of Clithero, by nodules of chert embedded in the limestone, often at regular distances, like the flints in chalk. A very striking section of this kind is seen in Vallus Bot- tom, near Wells. This chert is usually of a dark gray, or even black colour, but occasionally it is white, and in general its colour corres- ponds to that of the limestone beds which contain it. It rarely contains any organic nucleus, and thus differs from a large proportion of the flint nodules in chalk, with which, in the manner of its pro- duction, and in its relations to the calcareous rocks, it seems other- wise very analogous. The cherty layers in green sand and coralline oolite are also analogous instances, and we have hereafter to notice a similar character in a certain portion of the magnesian limestone. Proceeding northward, as the limestones are divided, these chert nodules are less plentiful, though in Coverdale, in Yorkshire, they abound, and at G-lenwhelt, on the Roman wall, shells of the genus Bellerophon have been detected in a very dark chert embedded in the limestone there. Chert Beds. The curious circumstance of conversion, as the miners say, or rather substitution of beds of chert for beds of limestone, generally at the top of the rock, is noticed in most parts of the lime- stone tract in England and Wales ; and very often it happens, as in Westmoreland, that the corals are converted to siliceous matter in the THE SCAB LIMESTONE. 173 midst of a block of limestone. It is probable that the rottenstone of Dentdale, Swaledale, Aldstone Moor, and Derbyshire may be occa- sioned by decomposition of the shale limestone near the surface. (Farey and Johnston.) A specimen collected by the author at Aid- stone Moor in 1820, which as to substance is a kind of rottenstone, contains several fossils of the limestone series, especially a very small species of trilobite. Similar facts are common in Derbyshire and the Yorkshire dales. Bitumen in solid masses lies very frequently in the beds of the scar limestone, and enters the cavities of productse, orthocerata, &c. ; as at Castleton, and near Clithero. In a liquid as well as solid state it will be noticed under the next division of the carboniferous strata. Physical Geography The surface of the country which is occupied by this rock in England is remarkably characteristic. Having been exposed to many repeated convulsions, it is thrown up to considerable altitudes, and placed in a great variety of positions favourable for the exhibition of the changes wrought on it by the atmosphere and streams. It is principally to the hardness and comparative durability of this rock, conjoined with its stratification and extensive system of joints, that we owe the grand ranges of vertical escarpments, which begir,d with a perpetual fortification the sides of the dales of York- shire and Derbyshire. Often, indeed, the wasting effect of the ele- ments is sufficient to excavate vertical rents and to insulate the great prisms of the rock which, especially in Dovedale and other parts ot Derbyshire, give the most romantic features to the valleys, while the same effects upon the high scars in Yorkshire and Westmoreland show like towers and bastions projecting from the wall of rocks or among the green herbage which has spread around them. Swallow Holes Frequently upon broad surfaces of limestone, espe- cially where it alternates with shale, we find ourselves suddenly stopped by a deep vertical pit in the rocks, worked by some little rill, or even by the mere gathering of rains, an effect more frequently observed in the course of streams, which, like the Calder in Cumber- land, traverse the ranges of this rock. These "swallow holes," as they are justly called, often serve to mark out uninterruptedly for miles the lines of limestones, whose actual edges may be obscured by the sliding of other matter over them. Swallow holes sometimes communicate downwards with internal caverns, which are nowhere so abundant as in the lower or scar lime- stones. It is to them we must refer the numerous caverns of Mendip Hills, in Somersetshire, the rocks of Clifton, the Forest of Dean, the celebrated caverns of Staffordshire and Derbyshire, and those beneath Ingleborough and Penyghent, in Yorkshire. Farther north, along the Pennine chain, where these limestones grow thinner, the caverns become less numerous, and in the same proportion the phenomenon 174 TJPPEE PALEOZOIC STEATA. of underground streams is rarely observed. This remarkable pheno- menon is evidently dependent on the thickness, as well as on the open joints and absorbent surface of the rock, and examples of the same kind occur in various other thick calcareous strata of England, as the oolites and chalk, as well as in the Jura limestone or oolite of Germany and France. It is to the same causes that we must ascribe the extraordinary strength of the springs which issue as clear as crystal from the openings of this rock ; but, being highly charged with carbonate of lime, soon deposit along their channel abundance of tufa. The herbage upon this limestonais usually short, elastic, and nutritious, and of a lovely green, which contrasts strongly with the bluish aspect of the moist surfaces of the shales, and the brown tints of the heathy moorlands of millstone grit. Toredale Series Lower Part. in Derbyshire. The shale and grit, or flagstone series above the scar limestone, is called in Derbyshire the limestone shale. It is about 500 feet thick, and consists principally of black or brown rather durable shale, forming a very wet soil, and causing land slips of great extent beneath the millstone grit summits. Mam Tor, the " Shiver- ing Mountain," near Castleton, exhibits these characters very de- cidedly. The shale, however, is interstratified to a great extent, and with a considerable regularity, with thick rocks of fine-grained mica- ceous gritstone, of excellent quality for building, and, as we have observed, generally at the bottom of this rock, with good durable micaceous flagstone, very similar to that in the more recent coal strata. Some less regular sandstone beds, called "cankstone," ap- proach very nearly to the nature of the ganister or calliard rocks of the coal strata. Mr. Farey, who considers these interpolations as anomalies, calls by the same name the very characteristic beds of black argillaceous limestone which lie in this shale, at Ashford, near Bake well, and near Ashborne, and produce lime fit for water cement. The frequent contortions of the limestone and shale are noticed by Mr. Farey as very remarkable. Ironstone balls He in bands in this shale, a few impressions of fossil plants have been collected, and very thin coal seams observed, not worth the expense of the fruitless trials in search of them. Liquid bitumen is mentioned at several points in connection with the limestones in this shale. in Yorkshire. This description of the Derbyshire limestone shale would apply with scarcely a varying sentence to the broad argillaceous strata which cover the thick limestones of Craven. The same abun- dance of shale, occasional interpolations of sandstone, ironstone, and laminated beds of dark limestone, the same traces of coal and liquid bitumen, the same contortions, may be traced in Craven and in Wharf- THE YOKEDALE LIMESTONE. 175 dale. More divided by sandstones and limestones, the same shale is recognized in Pendle Hill, Ingleborough, and Penyghent. The locality most remarkable for the abundance of liquid bitumen is at Flashy in Craven, where Mr. Preston has excavated a considerable quantity of the black argillaceous limestone, and found it associated with abundance of goniatites sphericus, besides large orthocerata and the curious bivalves, now known by the name of Posidonia. The nautili are generally inverted or have their cavities filled with liquid bitumen, and small solid lumps of the same substance are likewise met with. This, amongst others, is one strong reason for believing that the darkness of colour of these limestones and shales is due to the admixture of carbonaceous matter. 99 MiUgill Force, near Askrigg. A waterfall in Yoredale Rocks, the upper part limestone, the lower part shale. By a communication of Sir Philip Egerton and Lord Enniskillen, to the Geological Society, we have learned that the lower coal shale, as it has been termed in the western Irish coal fields, is precisely 176 TJPPEE PALEOZOIC STEATA. analogous, not only in mineralogical characters, and in its geological position between the mountain limestone and the true coal measures, but also in its organic remains, to the " limestone shale " of Derbyshire and Craven. The same goniatites, the same posidonise, (Bronn,) and other characteristic fossils occur in these far separated districts ; and in general, so strict is the accordance in all respects, that no geologist accustomed to the strata of the north of England could fail to recognize in the mountains above Enniskillen an exact analogy with Ingleborough and Great Whernside. 100 Gale Force, near Hawes. A waterfall in Yoredale Rocks, the upper part limestone, the lower part shale. Pennine Chain. In the further continuation northward of this series of shales, sandstones, and limestones, the limestones, as before observed, thicken, the alternations of sandstone and shale therefore become more frequent and decided, coal seams intervene, and the whole assumes the character of a complicated coal and limestone de- posit. It is possible, in tracing the different limestones enumerated in this series, to assign characters of local permanence. Thus the beds most remarkably stored with crinoidal reliquia3 are those of the " main lime," in Pendle Hill, Ingleborough, Cam Fell, &c. ; the black limestone of Whalley, Kirkby Lonsdale, and Dent is almost wholly deprived of them, like the same beds in Derbyshire ; productae abound on the top of the main lime, lithodendra are often plentiful in the beds below it, and one thin bed of limestone, at Aldstone PEITNTITB CHAUST YOREDALE SERIES. 177 Moor, receives, in consequence of the nature of its organic contents, the name of cockleshell lime. Chert lies frequently on the top of the main lime and underset or four fathom lime beneath it, as well as on the top of the little lime or crow lime above it. Slaty sandstone yielding flagstone occurs both in the alternations under the main line, and in those still lower between the underset and scar limestones. In one or other of these places in the section, flagstones are dug in Swaledale and Yoredale, in Graygarth Fell, near Kirkby Lonsdale, and Garstang, and it is probable that the flagstones of the north of Derbyshire belong to the same epoch. In some of the very hard sandstones which occur in this series in Swaledale, (like the cankstone of Derbyshire,) stigmariaB and other fossil plants occur, but in general the coal seams are not accompanied by many vegetable remains. A kind of rottenstone, as before mentioned, occurs in this series in Dentdale and at Aldstone Moor, and probably in many other places is produced from the decomposition of the limestone. The shales of this tract are usually dark, close, and fissile, and traversed by extremely long straight joints ranging north by west and south by east, east-north-east and west-south-west, dividing the rock into rhomboidal prisms. They often contain nodules of ironstone. A very remarkably indurated flinty shale, fit for use on the roads, which occurs in Swaledale and Yoredale above the main limestone, is called "black beds." The sandstones vary as to fineness of grain, and some of them, in their progress through Northumberland, assume such a coarseness of aspect, as to be in fact undistinguishable from the "millstone grit " of the next group. The marine fossil remains are almost wholly confined to the limestones and the cherts which sometimes replace them and the shales, but the few vegetable remains belong wholly to the sandstones and to the coal. Yoredale Series Upper Limestone Belt. The only additional remarks which we shall make on this portion ot the strata refer to the remarkable variation of character by which the limestone in several places is gradually changed to or suddenly replaced by chert. Thus in Swaledale the united thickness of the underset chert and underset lime (the former being uppermost) is nearly constant, but the thickness of each is extremely variable. In like manner in Wharfdale, about Kettlewell, the underset lime, just before it expires entirely under Great Whernside, is represented only by hard chert, and the main lime of the same district, before it thins out and dies away, becomes remarkably cherty, both by the change of whole beds N 178 TJPPEB PALAEOZOIC STEATA. and the introduction of chert nodules. There appears some reason to attribute this effect, in one case, to the operation of a vein, while in others it may, perhaps, be properly viewed as indicating merely the suppression of the calcareous deposit, independently of the siliceous. It must be owned, however, that the notion of miners, and that first suggested to the geologist, agree in assigning the effect in some in- stances, even independent of dykes or veins, to a real chemical con- version of the nature of the rock since its deposition. Millstone Grit Series. Mineral Composition. The difference of composition between the coarse sandstones which abound in this part of the series, and those of finer grain which alternate with the limestones below and the coals above, is rather apparent than essential. That all these sand- stones are composed of the broken and triturated ingredients of older crystalline, generally granitic compounds, is evident upon inspection. Their most abundant ingredient, sand, is plainly in the state of minute pebbles, and the size of these grains is sometimes so very small, that their coherent mass assumes almost a crystalline aspect, as, for example, in the calliard stones. On the other hand, in mill- 101 Millstone Grit. Carboniferous System, Yorkshire. stone grit they are of all sizes under an egg, though pieces of greater size than this are sometimes seen. These are evidently quartz pebbles of different kinds, corresponding to the quartz of veins and of COAL FOBMATION. 179 granites. Rose quartz has also been observed. The next abundant ingredient is felspar, which is probably present in all these sandstones. In the millstone grit this mineral occurs in rounded pebbles, whose internal structure is perfectly crystalline, like the large rhomboidal crystals in the porphyritic granites. Hence we learn clearly the history of such a sandstone deposit. The materials were derived from crystallized rocks, and were subsequently more or less rolled about and deposited in water. Mica, the third ingredient of granitic rocks, is less abundant in millstone grit, except in certain layers where it is occasionally very plentiful. It is usually of a pale silvery colour, and is hi very thin fragmentary scales. The decomposition of the felspar leaves a white, soft, unctuous substance, analogous to the kaolin of decomposed granite, and this forms a feeble cement for the grains of sand and mica. Occasionally in millstone grit, as in the other sandstones of the carboniferous system, we find oxidulous iron, and some other mineral substances not easily recognized, and in Lanca- shire, frequently fragments of shale, coal, &c. Everything, therefore, concurs to prove the mechanical watery origin of millstone grit, and by consequence of all the other sandstones associated with it, the differ- ences between them being only of degree. In the same manner nearly a gradual series of changes assimilates sandstone and shale, and it is sufficiently proved that the only really chemical aqueous deposit of this whole system is the limestone. The millstone grit of the southern coal fields is usually a much harder and more compact and cherty rock than the coarse pebbly strata which bear this name in the north of England. Finally, we must repeat the remark previously made, that this series is limited in ex- tent, not being of much importance or really characteristic of a cer- tain period except between the Trent and the Tyne. Through the remainder of Northumberland it is less remarkable than several other equally coarse grit rocks, called crag grits in Mr. Smith's map of Northumberland, which lie in the limestone series, considerably below the upper limestone belt. Excellent building stone is furnished by this rock in Yorkshire, Lancashire, and Derbyshire, and by its representative, the "Farewell Rock" of Dean Forest and South Wales, which have the valuable property of standing great heat, and are therefore employed in certain parts of the iron furnaces. The Coal Formation (or Coal Measures) consists of alternating strata of sandstone, shale, and coal, with courses of nodular ironstone, layers of bivalve shells, and, in a certain part, argillo-calcareous balls and nodules generally enclosing gonia- tites, pectens, &c. None of these strata differ individually in any essential points from 180 UPPER PALEOZOIC STRATA. the analogous deposits in the millstone grit, or limestone series beneath; their characteristic features are derived from their com- bination. It is, indeed, generally true, that the sandstones of the coal measures are softer and more argillaceous than those of the series below, that the coal shales are less indurated and less fissile than the " plates " of the limestone group, and the coal generally of better quality. But it is by the greater abundance of the coal seams, and by the absence of limestone beds that the upper part of the car- boniferous system is to be distinguished from the lower. It is, there- fore, perfectly conceivable, that cases may occur when the lower or calcareo-carboniferous group may, by the attenuation of its limestones and the thickening of its coals, become so similar to the upper group or true coal measures, that their relative ages can be only determined by collateral evidence. This extreme case has, indeed, hardly yet been observed in any of the known coal districts of the New or Old World, but the approaches to it in Northumberland and Scotland are sufficient to show that the coal measures have no other real differ- ence from the lower parts of the carboniferous system, than the total absence of the oceanic deposit of limestone. In many coal fields the reason of this difference is easily determined by the abundance of fresh water shells, beds of shale, and of ironstone, alternating with the coal. We have seen with what certainty the range of the mountain limestone can be followed through Great Britain, and its detached portions referred to their true place in the series of its beds, and thus geological parallels be established between the Mendip Hills, Derby- shire. Yorkshire, and Northumberland. The coal measures of Great Britain cover quite as large a surface, and are, perhaps, quite as well identified in mass ; but the details of the several coal fields are too discordant to permit many of these parallels to be drawn, without which the method of variation by which one such coal field becomes different from another cannot be determined. This is so entirely well known, that often in the same coal field the differences are so considerable as to render it difficult to identify the beds of the two extremes. It must be owned, however, that this is partly owing to the confusion of nomenclature amongst the workmen, though prin- cipally to the sudden changes of chemical quality to which the coal seams are liable. The extent of the coal fields of England and Wales may be seen upon Mr. Smith's and Mr. Greenough's Geological Maps ; those of Scotland also are sketched upon Mr. Smith's Map ; Mr. Griffith's Surveys and Mr. Weaver's observations have contributed much in- formation on the coal measures of Ireland, and many valuable notices in the " Annales des Mines, Annales des Sciences Naturelles," &c., make us acquainted with the same series in France. For the COAL FORMATION. 181 Netherlands the same journals and the Memoirs of Omalius d'Halloy, and for the German and Transylvanian coal fields the works of Villefosse, Freisleben, Hoffman, Sternberg, and others may be con- sulted. Mr. Conybeare has given a general view of these foreign coal tracts in the Geology of England and Wales. English oai Fields. -We shall consider the characters of the principal English coal fields in the following order : 1. The great northern coal fields of Northumberland and Durham, Yorkshire, Derbyshire, and Nottinghamshire, and the scarcely separ- ated fields of Cumberland, Lancashire, and Cheshire. 2. The south-western coal fields of South Wales, Dean Forest, Somersetshire, and Kings wood. 3. The coal fields of North Wales and Shropshire. 4. The central English coal fields. That the great northern coal fields of Northumberland and Dur- ham, and of Yorkshire and Derby shire, were formed under very simi- lar circumstances, probably connected towards the borders, and united in the deeper parts of the deposit, will appear from the following comparisons. The northern and southern portions of this great tract, though now separated sixty miles, agree in being formed within a belt of coarse pebbly sandstones (millstone grit), associated with thin coals, which overlie the mountain limestone, and in being covered unconformedly by the magnesian limestone. Coals of like quality are worked in these coal fields in the same parts of the series, bitu- minous coals of excellent quality in the lower part, quick burning coals in the upper part. Ironstone courses are most plentiful in the middle and lower part, where also lie the " mussel bands," of which regular layers have been some time known in the coal field of York- shire and Derbyshire, and are not without representation in that of Newcastle. This latter analogy is very remarkable, and the occur- rence of these mussel bands is almost a peculiar character of the great northern coal fields. A comparison of the details of these coal fields would afford an excellent test of the points of analogy, and the extent of varia- tion which may be expected to occur in neighbouring carboniferous deposits. The broadest part of the whole tract is between Halifax and Ferrybridge, or rather Went Bridge, in Yorkshire, where the dip is moderate and regularly to the south-east, the stratification not sub- ject to more than usual disturbance, and the greater part of the coal seams are worked to supply the wide-spreading industry of the West Riding. The whole coal system of the country is thus unfolded, all its products are employed, and the ranges of most of the beds per- fectly known. In addition it happens fortunately, that not only the millstone grit is remarkably distinct, and the series immediately 182 UPPER PALEOZOIC STEATA. above it, the lowest part of " the coalfield," unusually developed, and rich in organic remains, both animal and vegetable, but the upper- most part of the system beneath the magnesian limestone is also fully exhibited. There is therefore on all accounts one of the most com* plete coal fields in the island, and the fittest to serve as a type of comparison for the others. Yorkshire Coal Field. The following mode of classification of the Yorkshire coal seams will be found very natural and convenient, for the several groups of coals here assumed have certain collective characters derived from this combination, and occupy distinguish- able ranges of mostly argillaceous country between lines of sandstone hills. Magnesian limestone unconformedly covers the coal seams. /'Shales and Badsworth coal. Upper coals < Ackworth rock. vWragby and Sharlston coals. Red rock of Woolley, Hooton Roberts, over one particular thin bed of coal, and in no other part of the coal strata, is one of the most curious pheno- mena yet observed concerning the distribution of organic remains, and will undoubtedly be found of the highest importance in all infer- ences concerning the circumstances which attended the production of coal. In this part of the coal system we may observe, besides the very remarkable layer of marine shells, several occurrences of a peculiarly hard siliceous sandstone, called galliard, ganister, seatstone, &c., which, in fact, is the same thing as the crowstone of the mountain limestone series in Swaledale. This stone in some cases forms the floor or sill of the coal, a circumstance never observed in the upper coal strata of Yorkshire, which, indeed, always rest on a peculiar fine clay or seat earth, full of stigmaria roots, but in these upper strata galliard never occurs in its true character; Hence this whole group of strata of group may be appropriately termed the ganister coal series. The goniatites, nautili, and pectens which lie above one of the seams of coal, and still more the orthocerata which sometimes accompany them, are remarkably analogous, and, indeed, in part identical with fossils of the mountain limestone. The galliard is likewise to be compared with similar stones in the mountain lime- stone series, and therefore the ganister coal series might be with much propriety associated with the upper mountain limestone series of the Pennine chain, or with the millstone grit series of Derbyshire, and thus the flagstone would appear to be the lower limit of the true coal measures. But an examination of the neighbourhood of Halifax has shown another order of phenomena and another set of shells, which connect this same series with the upper or true coal measures. 184 UPPER PALEOZOIC STEATA. In the upper coal series of Northumberland, Derbyshire, and York- shire, are several layers of bivalve shells, commonly referred to the genus unio, from which the fresh water origin of these coal deposits has been inferred. In the midst of this series of ganister coals two layers of these shells occur, one of them about the middle of the series, considerably above the pecten coal, the other near the bottom, and considerably below that coal. No shells of this kind have ever been met with in the mountain limestone group, which there is every reason to consider as of decidedly marine origin ; not one of all the zoophytic, testaceous, or crustaceous reliquiae of this limestone has ever been found in the upper coal series. This opposition of zoological characters would appear to be fully explained if the coal deposits were admitted to have been accumulated in fresh water, or at the mouth of an estuary. And this opinion is perhaps generally adopted. We find then in the lowest coal series, which is placed on the line of transition between the marine and fresh water deposits, zoological and mineralogical characters common to both. Examined in detail we find these characters not mixed, but alternating in such a manner as if there had been one periodical return of the marine element into its ancient receptacle, after that had been for some time occupied by fresh water and its few inhabitants. The effects of this irruption having as it were worn out, the zoological characters of fresh water deposits are again manifested at intervals, in the upper system of coal beds, till this series is finally ended, and marine exuviae reappear in the magnesian limestone. If, from whatever cause, we could witness the effects of a general irruption of sea water into a modern lake of great extent and con- siderable depth, it is probable that the resulting phenomenon would be perfectly analogous in kind to those described above. But this irruption of the ancient ocean into the coal basin of Yorkshire, was probably not produced by any violent convulsion in that basin, (for there is no unconformity between the supposed fresh water and sup- posed marine deposits,) but by some disturbing causes of a more general character, or else originating at a distance. Similar occur- rences of marine shells in the same part of this coal series have been noticed in Lancashire ; they are in fact the same phenomena, and have been repeated there more than once in the lower coal measures or " mountain mine" group. It is easy to conceive that in the course of a gradual depression of the whole tract, by which successive beds of vegetables were accumulated, particular combinations might arise, which should admit for a time, and then again exclude the sea water with its characteristic form of life. The periodical revolution in the nature of the waters which operated the deposition of the lowest coal strata in Yorkshire, bears so remarkable an analogy to some of the FLAGSTONE BOCK. 185 phenomena of the marino-lacustrine tertiary deposits, that the same principles will probably serve as a basis for the explanation of both cases. In both cases we have a decidedly marine deposit below, and a decidedly fresh water deposit above ; the intermediate ground is not exactly neutral, but sometimes shows gradations from one to the other, and sometimes periodical alternations, accompanied, however, by so entire a parallelism of strata, that in seeking for the cause of these changes, we are compelled to have recourse to general subter- ranean depression, rather than to the blocking up of the outlet of an estuary, or to irruptions of the sea, arising from violent subterranean disturbances in a different quarter. Flagstone Rock. The lower coal series of Yorkshire is terminated above by a thick deposit of sandstone, which is never so coarse as the millstone grit, and generally appears to be more argillaceous. Its degree of consolidation varies according to localities and circumstances of drainage, but there is hardly a single point in its whole range, from the vicinity of Leeds to beyond Sheffield, where the title of flagstone rock is not eminently applicable to it. Along this whole range, by the valley of the Aire to Bradford, over the hills to Halifax and Elland on the Calder, and by Huddersfield and Peniston to Sheffield, it is the grand repository from which the immense demand for Yorkshire flagstone, both within the county and for all the Eastern and Southern coasts, is supplied. In particular situations, especially near the surface, it is often so thinly laminated as to pro- duce good roofing slate, while the deeper parts of the quarries produce capital building stone. This diversity of qualities is consistent with great simplicity in structure. It is a finely laminated stone, having its beds in general very parallel, and thus, according as the whole mass of a bed is employed, or as it is split into portions or resolved into its component plates by the action of natural causes, wallstone, flagstone, and slate result. The micaceous surfaces of every common flagstone immediately disclose to us the cause of its natural partings ; and further examination shows the whole thickness to be divided by other layers of mica into a number of parallel plates, which sometimes separate by the mere influence of the air, but generally, after being once dried, cohere together with considerable force. In this case it is difficult to say what technical use should be made of the term strata, which may with equal verbal accuracy be applied to the micaceous lamina, or the plates of slate or flagstone, to the beds of the rock singly, or the whole united mass of sandstone layers. In Mr. Smith's nomenclature the whole flagstone, rock is one stratum. However this may be determined, there can be no doubt that even the least and thinnest of the micaceous layers owes its origin to a particular operation of water, and required the intervention of a 186 TIPPER PALAEOZOIC STEATA. certain interval of time, to permit the separation of the grains oi sand and the scales of mica, It has been said above that the micaceous laminae, plates of flag- stone and beds of the rock, were all parallel. This is usually and very exactly the case, but in certain places while the beds and flag- stones, which are only lesser beds, are parallel to one another, the micaceous layers which make up the mass of the beds, form consider- able angles with the plane of their surfaces. Thus in fig. 5, p. 29, the upper part of the diagram shows all the part- ings parallel ; and this is the ordinary case of the flagstone rock, but in the lower part of the diagram the micaceous laminae are inclined to the other surfaces of parting. Such flagstones have generally a rough or ragged surface, and are much liable to scale off in irregular " shells," which disfigure the beauty of the stone. This oblique lamination of the mica strongly reminds us of the " false bedding" of millstone grit, and of the shelly beds of oolite, which probably were formed in the currents of slightly agitated water. The surface of the rougher flagstone beds is also liable to other peculiarities, as waves or undulations, like the ripple marks on a sandy shore, little hard knobs on one face corresponding to depressions on another, and sometimes a vermicular marking, which sometimes resembles the arrangement which semifluid matter assumes on smooth surfaces of stone, when these, after having been laid together, are forcibly pulled asunder, but in other cases indicates the trail, or pre- serves the form of free annelida. The micaceous layers are not unfrequently coloured with a mixture of carbonaceous particles. Vegetable remains lie in this rock in many places, and in consider- able plenty. Equisetiform plants in particular are abundant in it about Leeds, accompanied by trihedral fruits. Lepidodendra, sigillaria, &c. occur in it less plentifully. In general, what is said of the accidents of structure of the flag- stone rock of the Yorkshire coal fields applies to the laminated sand- stone rocks of the mountain limestone, and even to the analogous but more recent layers in the oolitic coal system on the coast of Yorkshire. muddle Coal Series. This is the most valuable part of the York- shire coal field, and includes as many as ten workable seams of coal, of various quality, with several layers of ironstone bands, one of them full of fresh water shells. The flagstone rocks define the series below, and the coarse, often iron-stained sandstones of Newmiller Dam, Woolley Edge, and Kawmarsh form its upper boundary. It may be convenient to divide this great group into three por- tions, thus : COMPAEISONS WlTfi O^HER COAL FIELDS. 187 Red rock of Woolley Edge. Furnace coals of Barnsley, &c., including the eight or ten feet seam. Eock of Horbury and Wentworth House. (Swift burning coals of Middleton, Dewsbury, &c., with bands Ironstone coals < of " mussels." ^Bituminous coals of Silkstone and Low Moor. Flagstone rocks beneath. Upper Coal Series. Upon the coarse rocks of Woolley Edge lies the upper series of coal measures in Yorkshire, which exhibits alter- nations of sandstones and shales very much like those of the middle and lower groups, but without the layers of mussels, and generally without the presence of productive ironstone bands. The reliquiae of plants are more rare in these strata, and the coal is of inferior quality, more earthy and less bituminous. Two considerable seams of coal near the bottom, worked at Wragby, Sharleston, &c., and one or two thinner seams nearer the top of this series, appear to be the last of the formation, and are unconformably covered, as are all the others in their turn, by the magnesian limestone, against which deposit the line of separation is hard and distinct. There are no trap dikes in this coal field, but many faults, passing nearly E.N.E. and W.N.W., and others nearly N.N.W. and S.S.E. The "cleat" of this coal is from N.W. or N.N.W. to S.E. or S.S.E. The cross cleat is sometimes hardly traceable. The small coal field of Ingleton and Black Burton in Lonsdale is thrown down on the south side of the great Craven fault. Comparisons with other Coal Fields. We are now in a condition to institute a comparison between the results of observation on the strata of the Yorkshire coal fields, and those which had been drawn from similar researches on the other coal districts of Britain and the continent. For this purpose it will be of little use to take into account the number or thickness, or chemical quality of the beds of coal, since these characters, however important locally, are too variable to guide us across even the whole extent of a single coal basin, and vanish altogether upon distant points. We must, there- fore, restrict ourselves to the most general divisions of the carboni- ferous series, and compare the coal fields with reference to the strata which separate the coal from the mountain limestone beneath, the occurrence of bands of ironstone and mussel-shells, the nature of the rocks and shales, and the distribution of organic remains. Notwithstanding the great interval in the superficial range of the coal strata between Aberford and Cockfield Fell, the series in the Durham and Newcastle coal fields is very analogous to that of Yorkshire. But hitherto, no layer of marine shells has been noticed in the lower part of the Newcastle coal fields, and, therefore, the inference 188 TJPPEE PALEOZOIC STRATA. of alternate inundations of the sea and fresh water cannot be applied to this coal field, though the general conclusion of marine deposits below, and fresh water deposits above, remains unimpaired. The total thickness of the coal measures is about 1,600 feet, the number of distinct layers or beds as usually noted by the miners about 600, the total thickness of the beds of coal rarely exceeds does not on an average equal sixty feet. No bed of coal is of greater thickness, even for a short distance, than six or seven feet several are so thin as to be of no value at present the total thick- ness of "workable coal," supposing all the beds to be found in a given tract, is not to be estimated at above twenty or thirty feet. The most part of the coal in this great district is of the coking quality, but in this respect there is much variation. The best coke, for locomotive engines, is now made from the lower coals in the Auckland district of Durham, and Shotley Bridge district of Northum- berland. The best " steam coal" is obtained from the north side of the Tyne and the Blyth district. The best "house coal" still comes from the remains of the " High Main" on the Tyne, and from the " Hutton Seam" on the Wear ; but the collieries north of the Tees have acquired a high reputation. As a general view of the groups of strata the following summaries may suffice : * Feet. Upper group of coal measures, including chiefly thin seams of small value (eight or more) in a vast mass of sandstones and shales, with some ironstone. At the base is a mussel band ; we estimate this at 900 (ON THE TYNE.) f HIGH MAIN coal.... often Strata and thin coals Metal coal... 6 feet. 60 1 6 30 3 (ON TH E WEAR AND TYNE.) Unknown. Five quarter coal 3 9 to 6 9 Main coal. 5 6 to 6 Strata and thin coals Stone coal Strata 83 Yard coal 3 Strata 90 BENSHAM SEAM 3 Strata with several vari-^ able beds and some> 150 layers of mussels ) Low MAIN COAL 6 Strata 200 HERVEY'SSEAM 3 Strata 300 BROCKWELL SEAM 3 Strata above millstone grit 200 The field is traversed by great dislocations, the most remarkable being the ninety fathom dike which throws down to the north, and * See Forster's Mining Section. Winch, in Trans, of Nat. Hist. Soc. of Newcastle, and Buddie in the same, Q QQQ u beds, 26 beds of coal / : Central series (Townhill sandstones of Swansea Pennant grit\ Q 2 46 " of the Bristol field) 62 beds, and 16 beds of coal / Lower shales, coals, and ironstones, (Merthyr,) 266 beds ; 34\ ^^ u beds of coal ) Abundance of ironstone beds and unionidae occur. Farewell rock and Gower shales, above the carboniferous limestone below. The coal on the north-eastern side of the basin is of a coking quality, excellent for the iron manufacture ; on the north-western it contains little or no bitumen, being what is called stone coal or culm ; on the south side, from Pontypool to Caermarthen Bay, it is of a bituminous or binding quality. The cause of these extreme differences in the quality of the coal is not known, and, indeed, the subject of the varying quality of a coal bed has never yet been adequately investigated. Many analogous though less striking examples are familiar to every coal-worker of sufficient observation and experience. The numerous excavations along the northern border of the South "Wales coal district, for the purposes of the iron manufacture, present us with a complete section of the middle and lower parts of the coal measures, the limestone series beneath, and the general base of old red sandstone. The lowest part of the coal measures consists of alternations of sandstone and shale ; the lowest bed (in the place of millstone grit) being a siliceous or sometimes a conglomerate sandstone. Above this series, two or three thin seams of coal occur, and these are followed by an argillaceous series, containing many thick and valuable beds of coal, and sixteen distinctly characterized layers of ironstone in thin beds and nodules. The general analogy of arrangement of the coals and ironstones to that which has been described in the northern coal fields, will be immediately obvious. It appears that the middle part of the coal strata is characterized by the predominance of coarse sandstone with carbonaceous specks, like that called Pennant in Somersetshire, and that a considerable thickness of such rocks intervenes between the upper and lower series of coal seams. This sandstone is occasionally highly micaceous and fissile, and yields very good flagstone and even roofing slate. There are no trap dikes in this great basin ; no considerable mass of trap enters it in any form ; though in Pembrokeshire the syenitic rocks adjoin it ; the change to anthracite which its beds undergo in proceeding westward, does not admit of explanation by the presumed 202 UPPER PALAEOZOIC STRATA. agency of heat depending on the local proximity of igneous rock. Nor is it proved or very probable that it is the effect of pressure, great as that has been in the anthracitiferous region. Carboniferous System of Scotland. In proceeding from the northward, we first meet the carboniferous system of the British Isles on the borders of the great synclinal hollow along which runs the valley of the Forth and Clyde. This great structural hollow, which is parallel to the chains of the Gram- pians and Lammermuirs, is filled in its central parts with a coal field, about one hundred miles long, from St. Andrews to near Greenock, and from Dalkeith to Ayr, and fifty miles broad, much interrupted by large trap masses rising through it, and sometimes interpolated between its strata. In general, the section shows, above the old red sandstone, a great variety of shales, and some thin limestones, con- taining products, spirifera, orthocratites, &c. At Burdie House, in the vicinity of Edinburgh and Dalkeith, the limestones yielded to Dr. Hibbert many land plants (lepidodendron, sphenopteris, &c.), and some bivalvular Crustacea, besides plenty of the great fossil fishes called megalicthys and holoptychius. At Carluke, near Glasgow, very beautiful fossils of the mountain limestone type occur. In general these coal fields appear to be older than those of the central parts of England, and, at least *in all the lower parts, to belong to the Berwickshire series, or submedial carboniferous groups. De- tached portions occur at Sanquhar and in the Isle of Arran, and we may join to the same local system the coal of Ballycastle in Antrim. Coal Field of Midlothian In the Midlothian coal field, in the counties of Edinburgh, Haddington, and Peebles, Mr. Farey, sen., in 1816, ascertained 337 principal alternations of strata between the surface in the town of Fisherrow on the banks of the Frith of Forth, (where the highest of these strata occur,) the commencement of the basaltic rocks forming the general floor and border of this important coal field. These strata lie internally in the form of a lengthened basin or trough, and consist of sandstone, shale, coal, limestone, ironstone, &c. ; 66 seams of coal, counting the double seams as one ; 7 limestones ; 72 assemblages of stone and other sinkings ; in all 5000 feet in thickness. Mr. David Milne* has published elaborate and well arranged details regarding the eastern part of the Scottish coal field a district of about fifteen to seventeen miles square, resting partly on trap rocks, and old red sandstone and conglomerate, and partly on Silurian and Cambrian strata. The coal series appears conformed to the old red ; * Memoir on the Midlothian and East Lothian Coal Fields, 1839. CARBONIFEROUS SYSTEM OF SCOTLAND. 203 and that is, on the Pentlands and Lammermuirs, unconformed to the older primaries. Two movements of elevation are inferred, one be- fore the old red, a second after the deposit of the coal, both very ex- tensive in their effects. The total thickness of the strata is 1000 to 1050 fathoms (6000 to 6300 feet). In 534 fathoms, it is known that Sandstone occupies 286 fathoms. Shale 188 Limestone 27 " Coal 21 Clay 12 " And computing the whole, we have as a probable summary : Sandstone 550 fathoms. Shale 360 " Limestone 51 " Coal 30 " Clay 22 " 1,013 fathoms. The number of the component strata is thus given : Sandstone strata above 4 feet thick 47, (the thickest mass, 200 feet.) Shale " 2 " 52, (the thickest mass, 130 ) Limestone " 2^ " 9, (the thickest mass, 40 ") Clay " 3 " 8, (the thickest mass, 28 ' ) (50 to 60, (the greatest thickness Coal seams " 1 " -c of a coal seam, 13 feet; ave- { rage, 3 j feet.) The limestones are situated in the lower half of the basin, thick- ening toward the south-east, in which direction the coal measures grow thinner. It is in the lower limestone strata that the plants and fish remains were found at Burdie House by Hibbert. In the upper series of coals unionidce occur. The shales contain continuously stratified ironstone (" black band"), and interrupted courses of nodular ironstone, each nodule generally containing organic matter as the nucleus of aggregation. The district is greatly traversed by faults or "slips;" 120 are mentioned ; 110 marked on the map ; one affecting the level of the beds 400 to 500 feet. Of 109 slips, 94 range between the north and west points of the compass ; 7 run due west ; the total effect, of 78 slips, being 35 downthrows to the south, 385 fathoms, and 43 down- throws to the north, 754 fathoms. The slips do not range parallel to the outcrop. The district is surrounded but not penetrated by large trap bosses ; the coal seams rise sharply toward them, as if to pass over having been uplifted with them, rather than by them. Greenstone dikes 204 TJPPEE PALAEOZOIC STEATA. of considerable breadth divide the coal. Along these, and espe- cially along the Niddry dike, which runs east and west, nine or ten miles, the usual hardening of sandstone and shale, carbonization of coal, &c., occur ; but there is usually no dislocation of the strata on the line of the trap dike. The coal seams, on the average, thicken toward the north. The lower limestones thicken toward the south. On the whole, allowing for waste, unattainable portions, and other circumstances, this one district may be admitted as likely to yield to the miner, for actual use, 2,250 millions of tons of coal the annual home consumption of Great Britain being (1839) estimated at thirty millions. The coal is partly "splint," partly "rough" or "'cheery," partly of the "cannel" or "parrot" variety the first containing most oxygen ; the last most hydrogen and nitrogen, and the least carbon. The splint has a long slaty structure ; the cheery coal is more cubical ; the cannel coal is of more compact and uniform texture, and still more nearly cubical. In .Fife, one of the coal seams at Dysart is 21 feet thick, and there are three others which exceed 10 feet. In the western part of the Scottish coal basin we may notice two main working districts in Lanarkshire and Ayrshire. Mr. Craig* has presented us with a useful summary of some of the phenomena. He classes the strata in the following order : Upper Red Sandstone series. Upper or Freshwater Coal series. Upper Marine Limestone series. Lower Coal series. Lower Marine Limestone series. Old Red Sandstone. The upper red sandstone group, consisting of red and variegated sandstones, shales, and thin coal seams, is supposed to be somewhat unconformed to the subjacent group. It spreads extensively in Lanarkshire and Ayrshire. In the upper or fresh water coal series, which is often tinged red, lie about thirty seams of coal, of which seven or eight are workable, from two-and-a-half to ten feet thick, in an area extending from Glasgow to Carluke, twenty miles long, and from six to fifteen broad. This district yields splint and cannel coal, but the greater part of the seams is of the more cubical varieties. Ironstones of the black band variety occur in three parts of this section, from fourteen to twenty- two inches thick. UnionidaB occur abundantly ; megalichthys Hib- berti, and gyracanthus, with the usual plants of the coal formation ; lepidodendron, sigillaria, stigmaria, asterophyllites, sternbergia, &c. Trees occur in situ. In the parish of Cambuslang, the following section occurs : * Reports of British Association for 1840. CAEBONIFEROTJS SYSTEM OF IRELAND. 205 Feet Inches. To the first coal 85 Soft coal 4 6 To the second coal 26 6 Soft coal 3 6 To the third coal 63 6 Shaft coal 5 To the fourth coal 65 2 (Ironstone here.) Soft coal 6 To the fifth coal , 83 Soft coal 3 To the sixth coal 10 (Ironstone here), Hard coal 3 6 Parting 1 6 Soft coal I 6 Beds below explored , 84 445 8 The upper marine limestone series, about two hundred yards thick, contains only two or three thin seams of coal, and three or four limestones, with shales, which yield crinoidea, nuculidse, euomphali, bellerophontidse, orthoceratidsD, &c. The lower coal series contains no limestone, but several coals, the lowest being a cannel coal two to three feet thick, above which, fifteen fathoms, is the main coal. Black band ironstones, from ten to sixteen inches, lie in this group, At the bottom of this series are many courses of ironstone nodules, with separating sandstones, and occasional thin limestones. The lower limestone series contains, besides the limestones, alumi- nous shales, and a sulphurous coal seam the whole resting on the old red sandstone. This series is found again in Ayrshire, yielding six or seven work- able coals, from two-and-a-half to seven feet thick a black band of ironstone, and several courses of nodular ironstone. Marine lime- stone underlie these coal measures. Fresh water shells, accompanied by nodular ironstones, and numer- ous reliquiae of equisetiform and filicoid plants occur without limestone beds in the coal fields of Clackmannanshire, Falkirk, and St. Andrews, but most of the Scotch coal fields, like that of the north and west of Northumberland, are 'formed by a development of the carboniferous limestone group of Yorkshire and Durham, and contain marine shells. Carboniferous System of Ireland. We now pass to Ireland, in which about half the whole area is occupied by rocks of the carboniferous system, which, if viewed on 206 UPPER PALEOZOIC STRATA. the great scale, offer the same general associations as the great Eng- lish and Welsh groups. The south of Ireland, as about Cork, shows almost the same sections as those of the western extremity of South Wales ; the north of Ireland offers more analogy to the coeval beds in the north of England. The great area of the Irish carboniferous system unfortunately yields but little coal, the upper and more generally productive portion (e) being perhaps only recognizable about Dungannon and Ballycastle. Most of the coal about the source of the Shannon, near Kilkenny and Newcastle, is of the age of the millstone grit (d), or of the lowest part of (e). The greater part of the area is occupied by limestones and shales of the groups cr, 6, c. Occupying the picturesque coast of Donegal Bay, Sligo Bay, and Killala Bay, and skirting the mountains of Connemara, the carboni- ferous system recovers the coast at Galway, and keeps it nearly to Dingle Bay. From this point, retiring inland, westward by Killarney to Mallow and Fermoy, it throws out branches and outliers to Ken- mare, Clonakilty, Kinsale, Cork, Rathcormack, Dungarvan, Water- ford, and Wexford, but the main outline turns again northward, skirting the mountains of Wicklow and Dubh'n, to the sea coast near the capital. It leaves the coast again near Drogheda, turning inland to Slane, Cavan, Monaghan, Armagh, and Donegal, and throwing off long digitations to Omagh, Maghera, and Lough Foyle, and outliers to Strangford Lough, Dundalk Bay, and Kingscourt. This immense field is broken by the older ridges of the G-altees, Tipperary, and other inland mountains. It is about 150 miles square ! The result of Mr. Griffith's long labour on the carboniferous system of Ireland is indicated by the following summary : e The coal series, but slightly represented. d Millstone grit series. It occupies a large space about the source of the Shannon, crowning with its huge blocks and crags the heights of Kul- keagh, and yielding coal, ironstone, and furnace grits to the iron- works on the western side. 500 feet. c Great shale series of Kulkeagh, with goniatites, posidonise, orthoceratites, bellerophontidae, &c. 600 feet. Upper limestone, cavernous, with coral bands in several stages. The calp series, gray and dark limestone, with shale and sandstone inter- posed in some districts. |^ Lower limestone. ( Carboniferous shale, locally rich in spirifera, strophomenae, fish re- a < mains, &c. (^ Yellow sandstone, with shale and occasionally limestone. The upper parts of the series (e d) are most conspicuous in the country about Lough Erne, and the sources of the Shannon ; about Kilkenny and Castle Conner ; and in the elevated country on each side of the estuary of the Shannon. The true limestone series is of CAEBONIFEKOTJS SYSTEM OF lEELAND. 207 amazing extent in the central parts of Ireland ; and the lower series arrives at its greatest importance in the southern tracts about Cork and Kinsale. Mr. Jukes has published* collective sections of this lower series, which show great variations in thickness, and great changes in the mineral aggregation. In Kilkenny county, at Knock- topher, the limestone rests on dark shale and yellow and brown sand- stone, 150 feet thick. (Below these are red slates, and red and green argillaceous sandstone, with ferns of the genus sphenopteris and an ancodon ?) Near Carrick-on-Suir we have, below the limestone, thin bedded yellow sandstone, and green and yellow shales, 150 feet ; (then alter- nations of yellow sandstone and hard red shale, 350 feet, unequivocal old red sandstone, &c., below 1800 feet.) Farther west, in the same county, the upper beds of yellow sand- stones and red shales thicken to 900 feet (the whole series, in- cluding old red, 4500 feet.) In the northern part of the county of Cork, we have yellow sandstones alternating with red shales and slates, 500 feet. (Eed shales and sandstones 400, and other red sandstones, &c., 2500.) South of Cork the series is thicker and more varied. Here we have Feet. Dark gray shales and slates, with occasional bands of greenish-gray grit 400 Brown sandstone, sometimes calcareous, and containing carts of Cucultea? 50 Dark green shales and slates, weathering brown or yellowish, with occasional bands of hard sandstone, all more or less affected by slaty cleavage 600 to 1000 Eed and green slates alternating 300 Red slates, with occasional yellow sandstone 500 Eed slates, with gray or purple sandstones 2000 and the bottom not reached. Again at Kinsale, Blue calcareous shales, with occasional thin bands of limestone and blue slates, with a few grit beds 2100 Blue strata, with greenish-gray grits predominating below 1700 Yellow sandstones, with shale partings 800 Eed and green slates passing down into red slates and sandstones... 1500 (base not seen.) The three upper masses correspond to Mr. Griffith's carboniferous slate and yellow sandstone, and the whole suggests a strong analogy to the series of strata in the west of Pembrokeshire, already de- scribed : in fact, my own observations in this part of the country (1843) assure me of the affinity of the two districts. Mr. Jukes is desirous of referring all these groups to the Devonian system. * Reports of the British Association, 1852. 208 UPPER PALAEOZOIC STRATA. The coal fields of Ireland, if we include in this term the mill- stone grit, occupy large tracts in that country, and are upon the whole analogous in general mineral characters and organic con- tents to those of England. The same absence of limestone, the same kind of succession of sandstones and shales, is remarked in them. Anthracite or stone coal, like that of South Wales, abounds in the Leinster and Munster districts ; bituminous coal occurs in Con- naught and Ulster. In Ulster the principal collieries are at Coal Island and Dungannon. The Munster coal district is stated by Mr. Griffith to be of greater extent than any English coal field, but it is much less productive. At Ballycastle the coal is found in connection with basalt. Carboniferous System in Foreign Countries. The carboniferous system of England and Wales is probably con- tinuous under a part of the Channel, and connected underground with the northern range of coal deposits in France and Belgium. From Hardinghen, near Boulogne, this range may be admitted to pass under the secondary and tertiary strata of France, to Valenciennes, Mons, Charleroi, Liege, and Eschweiler ; while frequently, from be- neath, thick limestones show themselves, having the same organic remains as the mountain limestone of England and Wales, and stand in similar picturesque cliffs on the Meuse, about Namur and Huy. This valuable and extended but narrow field is folded in sudden anti- clinals and synclinals. In the north-western, central, and southern parts of France, we have many spots of coal measures collected round or resting upon the tracts of older rocks, in Brittany, the Bourbonnais, Auvergne, and the Limousin. Near St. Lo, Quimper, and Laval ; at Vouvan and Chantonnay, in Poitou ; about Avallon, Decize, Autun, and Epinac ; about Roanne and Lyons, the most productive being at St. Etienne and Hive de Gier. Again about Aubenas and Alais, on the right bank of the Rhone ; and farther to the west, about Breves, Aubin, Rodez, Carmeaux, and near Perpignan ; finally, about Toulon and Frejus, small coal tracts are known and partially worked. In general, the French coal fields, though they show below the true coal measures some beds analogous to our millstone grit and shales, only in a few places exhibit the mountain limestone. The strata are in fact often found in discordant repose on much older rocks. Spain has also its detached coal fields in Catalonia, Arragon, and New Castile. Mr. Pratt has presented sections of these and older stratifications in the Asturias. Mr. Sharpe has noticed the coal of Portugal. Returning to the Rhine, we find the Vosges to yield some traces CARBONIFEROUS SYSTEM IN FOREIGN COUNTRIES. 209 of coal near Colmar ; and larger deposits at the foot of the Hunds- rlick, stretching from the Sarre at Sarrebriick nearly to the Rhine at Bingen and Mayence. Limestone is not here the general basis. Altogether, France may count about forty mostly small patches of coal, but according to Beudant,* whose summary we have given, only l-200th of the whole surface is occupied by this precious group of strata. Germany possesses several valuable coal fields. That on the river Ruhr, near Essen and Werden, (north of Elberfeld,) may be regarded as the eastern continuation of the Belgian deposit, emerging from beneath the very broad tertiary valley of the Rhine. It reposes on a valuable series of shaly or crinoidal limestones. In Bohemia, south of the Erzegebirge and Riesengebirge, is a large and valuable coal field, from which Count Sternberg extracted many beautiful plants. It is said to contain more than forty beds of workable coal. It extends eastward into Silesia, between Landshut and Silberberg. On the north-east and south-east of the Harz mountains detached coal fields occur ; more valuable tracts are worked on the north side of the Erzegebirge, near Zwickau and Dresden. The extreme northern parts of continental Europe contain little that is important in regard to coal, of any age, and scarcely a trace of the true coal formation. In Russia Sir R. Murchison admits, at Koula and other places, only feeble and scattered developments of a true coal formation above the wide mountain limestone of that great country. Farther to the east and south, Asia yields coal east of Heraclea, on the coast of the Black Sea ; on the borders of the Persian Gulf ; in China and India. The Indian coal fields of Cutch and Bundel- kund ; and on the Hooghly, at Merzipore and Burdwan ; and on the Ganges at Bhangulpoor, will be of great importance when opened by railways. On Mr. Greenough's lately prepared geological map of India, many other patches of coal are marked, but their geological date is still in some cases undetermined. Some are apparently of the mesozoic era. Borneo possesses coal, and the Birman territory yields it of good quality, if not of great extent. It is abundant in Australia, on the Hunter River, and is not absent from Van Die- men's Land. But it is in the northern parts of the American world that the most concentrated masses of coal occur on a scale, indeed, corres- ponding to the other physical facts of that wonderful region. Nova Scotia and New Brunswick have a considerable quantity of coal, and of various quality, some, as that of the Albert mine, having little of the structure or appearance of coal, and being anthracitic. In several places the beds are thick (ten to forty feet) . In the vast basin west of the Alleghany Mountains are very rich deposits of coal, anthracitic near * Cours Elementaire, 1851. P 210 TIPPER PALJEOZOIC STRATA. the primary rocks and metamorphic ridges, bituminous at a distance from them. " The bituminous coal field, embracing the western part of Pennsylvania and a part of Ohio, extends over an area of 24,000 square miles, the largest accumulation of carbonaceous matter in the world. In fact, the bituminous coal measures can probably be traced almost continuously from Pennsylvania to the Mississippi, and even intp Missouri, two hundred miles west of that river !" * Coal exists on the eastern slope of the Rocky Mountains : perhaps also on the western side of that great range. In some instances a single seam of coal is sixty feet thick, and near the middle of the basin sixty-five seams have been counted. These vast coal fields, " extending from the north-eastern counties of Pennsylvania to the northern part of Alabama, and from the great Appalachian valley westward into the interior of Ohio and Kentucky, include only a portion of the original formation, immense tracts having been destroyed by denudation ." t Upon a moderate estimate, its superficial area amounts to 63,000 square miles, fully ten times as great a space as all the productive coal fields of Britain ! Wide coal basins of equivalent age, the same authority tells us, lie remote from the Appalachian chain, far to the north-west, viz., that in the state of Michigan, and that which occupies a part of Indiana, Illinois, and Missouri. Beneath a great part of the North American coal fields limestone is extensively spread, comparable in a remarkable degree to that of the British Isles, and containing many of its best known organic remains. Thus viewed on a great scale, the carbo- naceous system is one of the most extensive, and furnishes very good evidence of the land and sea toward the close of the Palaeozoic period. General View of Circumstances under which the Coal Beds were deposited. Few subjects in geology have been examined under more various points of view than the question of the origin of coal, and the cir- cumstances under which it was deposited. We may wonder at the philosophical blindness which would permit in the last century pro- tracted disputes concerning the vegetable basis of coal, when so many thousand plants converted into that substance were found in the shales and sandstones of every coal district. But in those days this kind of evidence was so little understood, that the inimitable impressions of ferns and other plants from which we are now accus- tomed to reason concerning the climate and other conditions of the ancient world, were not even admitted to be reliquia3 of the vegetable kingdom. * Hitchcock's Elementary Geology. t Rogers (Prof. H. D.) in Transactions of American Naturalists, 1843. COAL BEDS. 211 There is no necessity to enlarge upon the proofs of the origin of coal from vegetables, drawn from an examination of its chemical con- stitution as compared with vegetable products, and the composition of the ligneous parts of plants, and from the unanswerable identity of the carbonaceous substance, into which a vast multitude of fossil plants have been converted. The chemical constitution of this carbonaceous product of the individual vegetables, is exactly analogous to the chemical constitution of coal ; and it is quite probable that hereafter the reason of the variations to which both are subject, v whether dependent on the original nature of the plant or produced by unequal exposure to decay before inhumation or metamorphic subsequent operations, will be as apparent as that of the general agreement arising from a common vegetable origin. Admitting then the vegetable origin of coal, the next question relates to the situation where the plants grew from which the vast mass of the coal seams was derived. Many of the plants accompanying coal are of unknown types, and some are too imperfect to permit any botanical deductions ; but the researches of naturalists have nevertheless been successful in deter- mining some general characters of this ancient flora. The greater number of these plants were decidedly terrestrial. They appear to be often analogous to tropical tribes of vascular cryptogamic, and coniferous plants. They grew then on the land, and it is probable from Brongniart's researches, that this land was in a high degree subject to heat and moisture, more so than perhaps even the coasts and islands of tropical seas, to the flora of which situations the coal plants present remark- able general approximations. We may now venture upon the main part of the inquiry which relates to the origin of coal, viz. whether the plants from which coal was produced grew in their present situations, and were there sub- merged and buried beneath marine or fluviatile deposits, or were swept down to their present repositories from distant situations by land floods and other causes. To guide us in this inquiry the follow- ing data may be premised : The generally uniform, or gradually varying, thickness of the several coal seams over a very large area ; and the many laminae which compose them. The peculiar kind of rock, usually indurated fire clay, below each bed of coal ; with roots of trees (stigmaria) . The broken and fragmentary condition and confused intermixture of the plants which accompany coal strata, and their being frequently without roots attached. The occurrence of the same species of plants in strata so dissimilar as shales, ironstones, and sandstones. 212 UPPEE PALAEOZOIC STRATA. The fact that in some districts only land plants and fresh water shells and fishes occur in the coal strata ; that in others very few plants and many marine shells occur, especially if limestone beds be present in the section. The occasional vertical position of broken stems of large trees and reed-like plants (fig. 105). The parallelism or con- formity of the several beds of coal. The extreme differences in the thickness of the seve- ral seams, and the occurrence of many very thin plates of coal through many of the coal shales. The occasional occurrence in a coal seam of large quartzose boulders, uncon- nected with any other mark of agitated water. Peat Bogs. De Luc and several eminent geologists, especially Adolphe Brong- niart, have supposed coal beds to have been originally a sort of peat bogs, or masses of vegetable reliquiae accumulated round the place of their growth, upon which other vegetables grew, and that subsequently these tracts of country during some extensive convulsions subsided below their former level, and were covered by various mechanical deposits. This hypothesis seems to have been suggested by the seeming analogy in some respects between the chemical changes which have happened to the vegetable matter of peat bogs and of coal, by the occurrence of stems of plants vertically in the coal strata, and by the supposed difficulty of otherwise explain- ing the acknowledged regularity of the coal beds. These circumstances certainly favour the hypothesis of De Luc, but they must make us overlook some difficulties in the way of adopting it. The formation of peat bogs is, as far as we know, not always of the kind here supposed. There are indeed two principal modes by which the carbonaceous mass called peat is aggregated. It is not by frag- ments of trees and herbaceous plants accumulated round the place of their growth, but of a variety of successively dying mosses and other * T Stems of sigillaria erect in (s") sandstone, shale, &c., above (R) roof of coal, with plants &c., but not entering (c'-') top coal. p Parting of shale (no marks of upright stems). cj Bottom coal, u Under-clay with stigmarian roots. s Sandstone, shale, &c. VEGETABLE DEPOSITS. 213 moisture-loving plants that the peat bogs grow up to the extent which they occupy on the high cold hills of the north of England. Subterranean Forests. There is, however, another kind of vegetable accumulation which may be thought to throw more light on the origin of coal. The turf or peat moors, as they are called in the north of England, which occur in low ground toward the estuaries of rivers, and along the margin of the sea, in many parts of England, contain a mass of vegetable matter, composed of mosses and other humid plants, roots of ling, &c., and envelop trunks of trees, some- times prostrated in particular directions, apparently cut by art or decayed by time. The roots are often seen in attitude of growth. In some places are oak, in others birch or fir, according, as William Smith has observed, to the nature of the soil below, which is sand, marl, or clay. With them often lie the remains of terrestrial quadrupeds, land shells, &c. The marls sometimes contain fresh water shells, but never, in the English levels, marine exuviae. In many places these accumulations of vegetable reliquiae are below the level of the sea, sometimes greatly so, and covered by various alternations of mechanical deposits, sands, and clays brought down by the rivers or deposited by the tide. These phenomena appear to admit of an easy explanation, if we allow that the relative level of the sea and land has been locally subject to variation, and thus the drainage of the country deranged. The greatest part of the vegetable mass grew in its present situa- tion ; it was a humid forest where the leaves and branches of the trees, mingling with the herbaceous covering at their base, formed an extensive carbonaceous mass, which enveloped the trees when they fell by any great violence of wind or flood, perished by natural decay near the base, or yielded to the axe of the old inhabitant. In cases where the situation was elevated, or otherwise removed from the action of the tide, the ancient forest has been sometimes converted to a lake, or overwhelmed with the ruins brought by a land-flood. Along the side of great rivers, where the level was permanently below the floods or tides, many successions of sandy and argillaceous deposits have taken place, and sometimes a second accumulation of vegetables ; and thus the whole alluvial sediment and subterranean forest resembles in some important respects the alternations of earthy deposits and carbonaceous layers which compose the ancient coal strata. i extent. This is a larger area than that of Scotland or Ireland.* In this immense area, the coal seam is not a simple mass, but divided into three main parts, the lowest is a pure coal, the middle is a bed of fine clay, and the roof coal is composed of alternating layers of coal and fine clay. This kind of formation is very common in all coal fields, and we learn from it that each coal bed is the fruit of interrupted and renewed accumulations of vegetables, the inter- ruptions being marked by fine sediments, implying distant agitation of water. Finally, in all coal beds, are very many thin alternations of pure coal and impure coal, with not seldom thin laminae of clay, impressed with the surfaces of plants above and below, and in some cannel coal beds are layers of fresh water shells. Then followed the drifting of sands and finer sediments, over the same area watery action of some kind occasioned, to speak in harmony with other geological facts, by local subsidence of that land. This ceasing, forests again overspread the same area, to be again covered up by watery action bringing sediments, in consequence of further subsi- dence. Nor must we limit this explanation to the examples in which the trunks of trees are found standing in sites above coal ; the same conclusion may be admitted where the clays under a bed of coal contain roots of the same sorts of trees. Now, this has been shown by Mr. Loganf and others to be a very frequent, almost strictly general phenomenon in the true coal measures, above the millstone grit of South Wales, Nova Scotia, Derbyshire, Staffordshire, &c. .Even where these are absent, or infrequent, the conformity of coal seams to a general type, in respect of the peculiar subjacent clays, makes it probable that similar causes are concerned in the production of them. If we attempt to trace the process by which the great result was attained, it will soon appear that enormous periods of time must have elapsed during even the aggregation of one coal seam, if all the plants in its mass grew on the spot. Assuming, with Liebig, that plants, deriving their carbonaceous elements from the air, fix annu- ally in their substance 1 Ib. English for 24'4 square feet surface of * H. D. Rogers in Trans, of American Geologists, 1840-2. He supposes the full original area to have equalled 90,000 square miles, t Geological Proceedings, 1840, 1842. 218 UPPER PALEOZOIC STRATA. ground, and further, that all this was preserved in a peaty deposit, growing up from them and under them, it would require 170 years to gather one inch of anthracite coal, and the enormous period of 122,400 years to accumulate 60 feet of the same. In the earlier ages of the world, the growth of plants in northern zones may be supposed to have been of tropical luxuriance, and thus the period be shortened ; and we may admit that some of the plants were drifted, and that would further contract the time ; but under any aspect, it must be concluded to have been very long. The substance of coal, examined by the microscope,* shows often the characteristic structure of coniferous wood, also the textures of other trees and plants. The ashes disclose similar woody textures, and if we mistake not, much merely cellular tissue in the Stafford- shire and Midland counties coal. Bowman, Hawkshaw, Buckland, Lyell, and Rogers, to name no more, have signalized themselves in late years by attempts to com- bine the large series of data now collected regarding coal into a clear view of its physical history. In the following sketch we present only the salient features of the subject, as they stand at present : 1. Conceive, toward the mouth of some great primeval river, or in some inland lake, or along some part of the sea shore, an area which is undergoing accretion of sediment, by periodical rather than gradual watery action. 2. Let the violent period of these accretions have passed, and let the area have received a general and nearly level deposit of the latest and finest sediments ; this is the under-day the-stigmarian bed mostly without shells, fishes, or ferns, not laminated, and rich in fine silica. 3. If it be a great inundation, which is now supposed to be passing away, from the river mouth or the lake, the clay might be so nearly drained and otherwise so circumstanced as to support superficial aquatic plants (Rogers), or to allow the growth of land trees, and be penetrated by their roots (Bowman) . In the former case, in a moist tropical climate, marshy or peaty plants, (as Rogers, following Buck- Ian d,f supposed the stigmaria to be) the plants might be conceived to have grown quickly over an immense area, as the Anacaris Alsin- astrum is doing in our modern canals and rivers. The parts of them more or less mixed with fine sediments, might be continually gathered in a peaty mass over the area, and from time to time op- pressed by thin laminae of such sediments, furnished by agitation of the water. 4. Trees might grow on the peaty mass and be thrown down, partly in it, but more especially on the top of it, with ferns and * Htitton, Fossil Flora of Great Britain, confirmed by Quekett, and other authors of later date. f Address to GeoL Society, 1811. FORMATION OF COAL. 219 many other plants, the latest growth of the marsh, pressed flat and enveloped in laminated shale, or retaining their figure in nodules of ironstone. This is the roof of the coal, and in it not unfreqtiently lie unionidse, cyprides, and fish remains, indicating the presence of water, under different conditions from those which accompanied the stigmarian under-clay. It is, in fact, the commencement of a series of deposits, which mark a subsidence of the area. 5. This subsidence brings in stronger currents of water, and their direct consequents, beds of sandstone, coarse or fine grained, with parallel or oblique lamina- tion, and in these a few scat- tered plants, especially stems more or less fragmentary, ir- regularly placed, of sigillaria, lepidodendron, or coniferous trees. But sometimes the stems are in their place and attitude of growth, over thick coal seams, and sinking into them, or even passing through them, if thin, to the stigmaria, which are their roots, below. These were enveloped and sus- tained by the sediments, and the scattered and fragmentary plants brought with them by the force of water. 6. This period of watery agitation and accumulation of sediments passed, the surface is again in the condition first assumed, subaqueous, or partially dried, the uppermost bed being the almost uniform under-clay, on which, and in which, vegetation is re-estab- lished. When sigillaria (represented by these roots called stig- maria) grew on the under-clay, we may believe it to have been nearly or within a few feet or inches of the surface. If the vegetable accumulation round them is thin, that is, occupied a short period of time, the stems sometimes remain attached to the root ; but if the accumulation is great, that is, occupied a long period of time, the stems do not penetrate the coal, and do not remain attached to their roots, except these roots be above or in the uppermost part of the coal. 7. When in the course of these changes the materials furnished 106 * T Stems of Lepidodendron and Sigillaria erect in (s") sandstone, shale, &c., and spreading roots in and under the thin coal c. v Under-clay with rootlets. s' Sandstone, shale, &c. 220 TJPPEB PALEOZOIC STRATA. by vegetation were slowly, but completely disintegrated in water, by eremacausis, without being pressed by incumbent earth, fishes and shells might leave their remains in the coal, as happens in the cannel of Wigan, which, however excellent as fuel, is rather a fine carbonaceous mud, than a truly laminated coal. 8. The under-clay is usually of a white or pale bluish colour, and contains little or no peroxide of iron, a circumstance now understood to be the effect of deoxidation, by decaying vegetable matter. The reader may consult for further details on this subject the in- teresting papers on the South Joggins coal deposit, by Logan, Lyell, and Dawson, in the Proceedings of the Geological Society. He will remark as an essential, indeed the fundamental point in the explana- tion, the frequently repeated subsidence of the area ; this, as being a well established and ordinary geological event, proved by many examples, may be at once accepted as true. As a necessary result, drifting of earthy and vegetable materials from the land follows. Thus, in some particular cases where the coal beds are the least regular, and have no true stigmarian under-clays (as in some of the coals of the millstone grit and mountain limestone), we may rather believe, with Sedgwick, that the coal bed is a drifted mass than the accumu- lation from growth in situ. In all cases we must attribute to this cause the scattered plants in the coal strata, and some share in modi- fying the aggregation of the plants which really did grow on the spot. One curious proof of the action of such currents has been already noticed, the occurrence of rounded boulders of quartz rock or hard sandstone. This appears in the coal of Newcastle, and in that of Norbury, near Stockport. There being no other indication of violent currents which might drift such large masses, this has been found somewhat hard of explanation. Perhaps the following simple obser- vation may meet the case. Trees with branching roots sometimes pick up and entangle in their growth large and small stones and other objects in the ground. These are to be seen where trees grow by watersides, or from other causes have their roots exposed. Con- ceive such a tree drifted, and deposited, and decomposed, the stones floating and carried along with it would be enveloped in the mass of matter formed by and around the tree. This implies, perhaps proves, in the case even of pure coal, resting on stigmaria clay, some influence of drifting for the accumulation of the mass. It is probable that in lakes which receive floods overcharged with sediment, and which in consequence are frequently muddy, few kinds of mollusca, or fishes, or other animals would live, and that the mol- luscous remains would be such only as belonged to bivalves, like unio and anodon, or univalves, like paludina, which never come to the surface for respiration, but remain at the bottom of the waters. The DISTURBANCES OF THE CARBONIFEROUS SYSTEM. 221 shells found in coal tracts, supposed to be of fresh water origin, are principally unionidse and anodontidaD. It is also probable, for the same reason, that only a small number of the animals or plants actually existing in the sea at any one time would be found within the area of a very muddy estuary, and thus we see the reason why the coal basins which contain no fresh water shells, and are from other circumstances presumed to be of marine origin, are most frequently devoid of animal remains, except in the cal- careous layers or nodules which may occur in them. These calcareous deposits evidently mark periods during which the chemical precipi- tations from the sea were little or not at all troubled by the mechani- cal aggregations from the floods of the land. As many basins of fresh water, estuaries, or seas, as received the vegetables and sediment brought down by the floods, so many dis- tinct series of carbonaceous and argillo-arenaceous deposits would be produced ; there would be no particular agreement between them in the number, thickness, quality, and arrangement of the coal seams, rocks, or shales, or ironstone, but a general agreement, depending on the common physical conditions of the region. But in the same basin, even over very large areas, there would frequently occur par- ticular agreements, in many respects ; coals of particular quality, rocks of certain kinds, beds of ironstone, and layers of shells, may be traced over large tracts and assigned to definite places in the. general section. Convulsive Movements of the Carboniferous System. Nothing appears more clear in geology than that the same parts of the globe have been alternately subject to gradual alteration, through the slow and equal action of the ordinary system of nature, and to sudden extreme changes induced by the shorter dominion of violent disturbing forces. The preceding descriptions sufficiently show how regular was the action of the causes which permitted the immense accumulations of chemical deposits, earthy sediment, and vegetable reliquiae, on the beds of ancient lakes or estuaries, and for how long a period this pro- cess continued, the prodigious number of alternations in the deposits sufficiently attests. It was, indeed, compared to the present state of things, a period of remarkable excitement as to the vigour of vegetation, and perhaps also as to the abundance and force of inun- dations ; but the parts of this series, compared with one another, and with analogous strata of different ages, furnish proof that the whole was the result of what may be termed the then ordinary course of natural operations. Extern of these Disturbances. But this long period appears to have 222 TTPPEK PALEOZOIC STRATA. come suddenly to an end, and the characteristic regularity of its de- posits to have been interrupted by a general eruption of disturbing forces which have left the traces of their power and extent in all the coal fields of Europe and America. As after the deposit of the slates violent dislocations happened and were succeeded by the old red conglomerate, so after the deposit of the coal, similar and equally extensive interruptions of the planes and courses of strata were fol- lowed by the analogous deposit of lower Red sandstone. In the course of these operations, the whole thickness of at least the stratified mass of the crust of the globe appears to have been broken in many direc- tions, so that the divided portions were raised or depressed a few inches, many yards, or hundreds of fathoms from their former level, and placed in new situations, with various angles of inclination to the horizon and in various directions. Scarcely a mine or colliery is worked in strata of this era in any part of the world which is not crossed by several faults or dislocations of this nature, and it is al- ways found that they divide and displace in the same direction the whole series of the strata to the greatest depths which man has reached. That these dislocations happened after the complete deposit and induration of the coal strata is evident ; that they followed almost immediately, and happened nearly at the same period of time, in almost all the coal tracts, appears certain from the general fact, that the disturbances of the coal seams rarely extend into the newer strata of magnesian lime and Red sandstone. There was, therefore, a general disturbing agency employed to break up the consolidated planes of the carboniferous strata ; and from the occasional filling of the dislocations with basalt, various crystallized minerals, and other igneous products, no doubt can remain that the principal agent was that general source of heat which is included within our planet, and which finds vent for its energies in different places at different times. To particularize all, or even the most remarkable of the faults of the carboniferous systems of different countries, and to notice all the variations of their appearance, would be entirely foreign to the inten- tion of this treatise ; such details must be sought in special descrip- tions of the several mining districts and coal fields. But we shall notice some of the most predominant of these dislocations, which appear to have caused the most extensive alterations in the level of the strata, and to have been most efficient in uplifting particular ranges of land, and giving new boundaries to the ocean. That most of the carboniferous deposits were originally limited in area, has been already stated, and therefore we must be cautious not to infer the violent separation of two coal tracts from the mere fact of their disunion, without reference to the connecting inferior strata. DISTUEBANCES IN THE CAEBOKEFEEOTTS SYSTEM. 223 Thus the coal fields of the Forth and the Clyde were probably limited by the previous elevation of the ranges of the Grampians and the Lammermuir, and though presenting strong analogies with the northern coal fields of Northumberland, there is no reason to affirm that they were ever joined to them. Keeping this in view, and guided by a knowledge of the characteristic points of the several systems of strata, we shall be able, with more or less facility, to de- termine the amount of the disturbance of position induced on any given coal tract, and thus to restore in imagination the original con- dition of the strata. The separation of the great coal fields of North- umberland and Durham on the one hand from those of Yorkshire and Derbyshire on the other, appears to have been caused by a general elevation in an eastern and western range of the whole of the tract intervening between Wharfdale and Teesdale. In consequence of this and the waste of the elevated surface, it hap- pens that while the lower parts of the carboniferous system are con- nected, the upper parts are entirely divided, and the magnesian lime- stone lies level on the coal of Durham, and millstone grit of Nidder- dale, and again covers coal in Airedale. Pennine Chain. Again, all the great northern carboniferous tracts are arranged with relation to an almost continuous northern and southern axis of elevation, from the mountains round the source of the South Tyne to Ingleborough, through Bolland forest, by Pendle Hill and the western border of Yorkshire, to the limestone district of Derbyshire, while the particular fields of Hartley Burn and Black Burton, depend upon two cross lines of dislocation or fault, the former passing eastward under the name of the main, or 90 fathom dike, from near Brampton to the sea side near Tynemouth, and depressing the strata to the north, while the latter ranges east-south-east by a remarkable line of slate rocks from Kirkby Lonsdale to near Grassing- ton, and throws down to the south. The carboniferous rocks which surround the lake mountains have certainly been affected by eleva- tions subsequent to those which in that district followed the deposit of slate, and anterior to the deposit of the superincumbent Bed sand- stone. A large proportion of the mineral veins which divide the carboni- ferous limestone series of Aldstone Moor, and the mining dales of Durham and Yorkshire, range east and west, and may be reasonably viewed as lateral fissures proceeding from the main axis of elevation which they join nearly at right angles. The same direction at right angles to the continuation of the same principal axis of elevation is recognized in the veins of Derbyshire, some of which range to the north-east and others to the south-east, and, though with consider- able variations, appears to prevail amongst the numerous faults or slips of the coal field of Yorkshire. 224 TJPPEB, PALAEOZOIC STRATA. The great northern and southern axis of elevation of the carboni ferous series in Derbyshire is broken across on the north, near Castle- ton, and appears to be terminated on the south, near Bradbourn, by great cross faults ; and the whole of the coal measures of Notting- hamshire and Derbyshire, on the east, and of Staffordshire on the west of the axis, are cut off by rapid dip or sudden depression to the south. It may be conjectured that the line of this depression is pro- longed beneath the red rocks of Cheshire to the estuary of the Dee, and it is, perhaps, not improbable that the red marl and sandstone which fills the drainage of the Mersey covers a large extent of de- pressed coal strata. Further researches may very probably ascertain the existence ot several other buried coal tracts in the midland parts of England near the detached coal fields of Leicestershire, Warwickshire, and Staffordshire. Forest of Dean. The Forest of Dean is a singular basin of coal strata with a belt of mountain limestone and old Red sandstone, rising from a plain of new Red sandstone, and looking over the vales of Wye and Usk to the similar but more extensive district of South Wales. The general line of elevation in this immense coal field is east and west, and the strata dip from both the north and the south toward the middle ; but Mr. Conybeare has shown that along the middle runs an internal axis of elevation, so that the coal field is a double trough. The elevation of the Mendip Hills, and other tracts of carbonifer- ous limestone in Somersetshire and Gloucestershire, as well as the curious faults in the collieries near Bath and Bristol, must be re- ferred to the same epoch, for the superior strata of red marl and the oolites are unaffected by them. This short review shows us what extensive changes in the relative level and area of land and water were effected in these regions imme- diately after the deposition of the coal strata, and similar results have been obtained from researches in various parts of Scotland, Arran, and other islands, and in the large coal tracts in Ireland. Ardennc*. In extending our researches to foreign countries, we must remember that the exact date of the disruption of the strata is determined by limiting the epoch between the date of the formation of the strata broken, and that of the unconformed stratum next in- cumbent or adjacent. Thus on passing from the Ardennes moun- tains to Luxemburg, we descend from the elevated slate range to a horizontal mass of new Red sandstone, followed by lias and oolites ; and in this case it is clear that the elevation of the Ardennes pre- ceded the deposition of new Red sandstone ; but where that stratum is absent (the general case along the border of these mountains,) we must be content with inferring that the epoch of the disturbance was DISTURBANCES OF THE CARBONIFEROUS SYSTEM. 225 older than the oolites. On this account it is not easy to fix the date of the disturbances of the coal series of Belgium and the north of France more precisely than by saying, it was anterior to the oolites, since these are the oldest strata lying unconformedly over the coal. The slips and dislocations of the carboniferous system almost in- variably agree as to the direction of their slope, compared to the level of the strata, with the general law stated before ; but there are a few cases of such extraordinary dislocation, as at Valenciennes and in Somersetshire, that the beds of coal and accompanying strata are bent into a sigmoidal flexure, and in part turned completely upside down. Lesser cases of flexure of beds are not unfrequent. With respect to the degree of distinctness of the planes of the slip, we may remark that this depends very much upon the consolidation of the strata divided. Thus while in limestone and solid sandstone the planes or cheeks of the slip are clearly traced, they are almost obliterated in shales and thin bedded sandstones, either by a bending at the surface of a fracture, or by a filling up of the chasm irregularly with fragments from the sides. This applies even to the case of a mineral vein which crosses alternating strata of three different kinds, as in the mines of Aldstone Moor and Swaledale, where the metallic and sparry substances are crystallized in abundance in the open space between the hard cheeks of limestone and gritstone, but are far less plentiful in the obscure and contracted interval between faces of shale. In districts which appear to have been once remarkably subject to igne- ous eruptions, the fissures of the dislocations are often filled by basalt, both in the subjacent limestone and superior coal tracts, as in the counties of Durham and Northumberland ; but the metallic ores and spars which properly constitute a mineral vein, and which abound so much in the limestone as to give it the name of metalliferous, are very sparingly found in the fissures of the coal tract. Affinity between Veins and Rocks. However it is to be explained, there certainly appears to be some affinity between the metallic matter of the vein and the nature of the strata which it traverses ; and though no doubt can be entertained that the veins are posterior to their including rocks, the frequent passage of strings of ore into the neighbouring strata, occasional nidiform masses, and solitary crystals of the metallic substances embedded in the interior of the rocks, besides the very remarkable examples of crystals of blende, galena, &c., in the interior of brachiopodous bivalves, seem to prove that the metallic matter has been in these cases deposited by a kind of secretion. Nor is this supposition, which is strongly confirmed by observations in the slate districts of Cornwall, in the least inconsistent with what is known of the diffusion of metallic substances by gradual heat much below their melting points. Breislac and Henry mention cases of the transference and collection of metallic matter (copper) Q 226 UPPER PALEOZOIC STRATA. at an ordinary roasting heat, and the well known example of titanium extricated from the melted iron of our furnaces leads to analogous conclusions. We may, therefore, very consistently maintain, that mineral veins are posterior to the strata which they divide, and yet allow that the transference of metallic substances may have been effected by the ordinary agency of heat, or the influence of electricity, so as to impregnate the strata under particular circumstances with the contents of the neighbouring veins. Such secretions of metallic substances then do not require us to admit the contradictory dogma that the veins occupying fissures are contemporaneous with the strata which have been split by these fissures. The metallic substances usually yielded by the carboniferous lime- stone are most of the ores of lead, zinc, and copper, with oxides and carbonate of iron, and the vein-stuff, or matrix, is calcareous spar, fluor spar, sulphate and carbonate of barytes, strontianite, quartz, &c. ORGANIC REMAINS CARBONIFEROUS SYSTEM. (Genera supposed to be confined to this system in Capitals.) PLANTS. ADTANTITES, 2 Newcastle. Alethopteris, . 7 Newcastle, Wales. ANABATHRA, 1 Berwickshire. ANNULARIA, 2 Somersetshire. ANTHOLITHES, 2 Salop, Newcastle. APHLEBIA, . 1 Newcastle. ASPIDIARIA, 5 Somerset, Yorkshire. ASTEROPHYLLITE Calamites, 12 17 Newcastle, Salop. Yorkshire, Lancashire, &c. CARDIOCARPON, 2 Newcastle. Carpolithes, 5 Jarrow, near Newcastle. CAULOPTERIS, 3 Somerset. Chondrites, 1 Salop. CREPIDOPTERIS, 1 Newcastle. CYCLOCLADIA, 1 Newcastle. Cyclopteris, CYPERITES, 8 1 Yorkshire, Salop, Newcastle. Leebotwood, Salop. DADOXYLON, 2 Newcastle. DIPLOXYLON, 1 Yorkshire. Endogenites, Equisetites? . 1 1 Salop. Lancashire. Flabellaria, . 1 Cumberland, Salop. HALONIA. 5 Yorkshire, Salop. HIPPURITES, 2 Newcastle, Dean Forest. HYDATICA, . 2 Yorkshire. Hymenophyllites, 2 Newcastle. KNORRIA, 3 Newcastle, Salop. LEPIDODENDRON 19 England, Wales, Scotland. LEPIDOPHYLLUM 4 Somerset, Newcastle. LEPIDOSTROBUS, 4 Newcastle, Salop. OBGANIC BEMAINS CAEBONIFEROUS SYSTEM. 227 LOMATOPHLOYOS, 1 Edinburgh. LYCHNOPHORITES 1 Yorkshire. Lycopodites, 2 Newcastle, Durham. LYGINODENDRON, 1 Ayrshire. MEGAPHYTUM, 3 Newcastle, Scotland. MUSOCARPUM, 1 Lancashire. MYRIOPHYLLJTES, 2 Yorkshire, Durham. Neuropteris, NOEGGERATHIA, 23 2 England, Wales. Newcastle, Lancashire. Odontopteris, Otopteris? 4 1 Yorkshire, Staffordshire. Glee Hills. PALMACITES, 1 Salop. Pecopteris, 27 England, Wales, Scotland. Peuce, . 1 Durham. PlCEA, 1 Durham. Pinites, 5 Newcastle, Berwickshire. PlNNULARIA 1 Salop. PlTUS, 2 Berwickshire. POACITES, 2 Devon, Lancashire. POTHOCITES, 1 Near Edinburgh. PROTOPTERIS, 1 Whitehaven. RHABDOCARPUS, 1 Newcastle. SAGENARIA, 6 Yorkshire, Newcastle. SELAGINITES, 1 Edinburgh. SIGILLARIA, 22 Newcastle, Wales, &c. SPHENOPHYLLUM 6 Somerset, Newcastle, &c. Sphenopteris, STERNBERGIA, 31 1 England, Wales, Scotland. Scotland, England, Wales. STIGMARIA, Trigonocarpon, 3 6 England, Wales, Scotland. Lancashire, Salop, Somerset. Ulodendron, ..- * 7 Edinburgh, Newcastle. Tragos? semicirculare, . AMOKPHOZOA. 1 Ireland. ENDOTHYRA, Nodosaria, Textularia, . FOEAMINIFERA. -, / Beetham Fell, Westmoreland, near White- \ well, &c. 1 Tyrone. 1 Yorkshire. ZOOPHYTA. Amplexus, ASTR.EOPORA, Aulopora, Campophyllum, 5 1 3 2 4 Cladochonus, Clisiophyllum, COLUMNARIA, Cyathaxonia, Cyathophyllum, CYATHOPSIS, 5 8 2 2 11 2 South of Ireland. Yorkshire, Derbyshire. Northumberland, South of Ireland. South of Ireland. Bristol. Yorkshire, Bristol, &c. Derbyshire, Yorkshire. Kendal, Derbyshire, Wales. Derbyshire, Fermanagh. Kendal, Derbyshire. Yorkshire, Derbyshire, Somerset Isle of Man, Scotland. 228 TJPPEE PALJEOZOIC STRATA. I Diphyphyllum, Favosites, Fistulipora, Gorgonia ? HETEROPHYLLIA, LlTHODENDRON, . LlTHOSTROTION, . ,. v " 3 3 2 2 2 7 8 4 MlCHELINIA, . 'V '"'* - ! MORTIERIA, NEMATOPHYLLUM, PETALAXIS, . . . ^ + Sarcinula, 6 1 4 1 3 3 Strephodes, . Strombodes, . Syringopora, 1 3 5 8 Derbyshire. Northumberland, North Wales. Yorkshire, North of Ireland. Derbyshire. Ireland. Derbyshire. Yorkshire, Derbyshire, &c. Bristol, Salop, Wales, Ireland. Derbyshire, North Wales. England, Wales, Ireland. Derbyshire. Derbyshire. Ireland. Derbyshire, Wales. Yorkshire, South Wales. North Wales, Bristol. Derbyshire, Yorkshire. England, Wales, Ireland. England, Wales, Scotland. ECHINODERMATA. CODONASTER, Pentremites, PENTREMITID^E. Yorkshire, Derbyshire. England, Wales ; Ireland. Archaeocidaris, Palaechinus, PERISCHODOMUS, FAL^ECHINID^E. 5 Yorkshire, Derbyshire, Ireland. 5 Yorkshire, Ireland. 1 Wexford. Actinocrinus, ASTROCRINUS, ATOCRINUS, Cupressocrinus, Cyathocrinus, DlCHOCRINUS, EURYOCRINUS, MESPILOCRINUS, PLATYCRINUS, POTERIOCRINUS, KHODOCRINUS, SYCOCRINUS, SYNBATHOCRINUS Taxocrinus, CRINOIDEA. 23 England, Wales, Ireland. 1 Yorkshire. 1 Ireland. 2 Derbyshire. 10 Yorkshire, Derbyshire. 3 Yorkshire, Somerset. 1 Yorkshire. 1 Yorkshire. 25 England, Wales, Ireland. 20 England, Wales, Ireland. 9 Yorkshire, Bristol. 3 Yorkshire. 1 Yorkshire, Bristol. 3 Fermanagh, Yorkshire. Arenicola, Sabella, Serpula, Serpulites, SPIROGLYPHUS, Spirorbis, ANNELIDA. 1 Lancashire. 1 Ireland. 6 Manchester, Salop, &c. 3 Lancashire, Ireland. 1 Ireland. 4 Ireland. ORGANIC REMAINS CABBONIFEBOTTS SYSTEM. 229 Bairdia, . . 2 Cypridina, 2 Cypris, Dithyrocaris, ENTOMOCONCHUS, 4 6 1 Eurypterus, 1 Limulus, 3 CRUSTACEA. ENTOMOSTRACA. 2 Ireland. Ireland, near Edinburgh. Newcastle, Lancashire. 6 Tyrone, Glasgow. Yorkshire, Ireland. Near Glasgow. Salop, Deny. BRACHYMETOPUS, Cyclus? GRIFFITHIDES, PHILLIPSIA, TRILOBITID^B. 3 Ireland, Derbyshire. 1 Yorkshire. 5 Ireland, Northumberland. 7 Yorkshire, Derbyshire, Ireland. Macrura ? MACRURA. 1 Salop, near Birmingham. Corydalis, (Neuropt.) Curculionides, INSECTA. 1 Coalbrook Dale. 2 Coalbrook Dale. Ceriopora, Diastopora, Fenestella, Glauconome, Hemitrypa, ICHTHYORACHIS, ORBICULITES, Polypora, Ptilopora, Pustulopora, Retepora, SULCORETEPORA, Vincularia, BRYOZOA. 6 Yorkshire, Ireland. 1 Wexford. 19 England, Ireland, Scotland. 5 Yorkshire, Ireland. 1 South of Ireland. 1 Clare. 1 Ireland. 8 Yorkshire, Ireland. 2 Yorkshire, Ireland. 2 Yorkshire, Ireland. 2 Lanarkshire, Ireland. 2 Yorkshire, Ireland. 3 Ireland. Athyris, Camerophoria, Chonetes, Discina, . HYPODEMA, Hepta3na, &c., BRACHIOPODA. 12 Northumberland, Derbyshire, Ireland. 3 Derbyshire. 1r (Northumberland, Westmoreland, York- lb t shire, Wales, Ireland. 6 Ireland, Yorkshire. 1 Derbyshire. 7 Yorkshire, Ireland. 230 UPPEE PALJEOZOIC STEATA. Lingula, Orthis, 6 12 Yorkshire, Derbyshire, Ireland. Ireland, Yorkshire. Pentamerus, 1 Ireland, Kendal. Productus, . 43 England, Scotland, Ireland. 1 Yorkshire, South Wales. % Rhynchonella, Spirifera, 22 57 England, Scotland, Ireland. The British Islands. Strophalosia? 1 Yorkshire. Terebratula, 3 Yorkshire, Ireland. MONOMYARL4. Avicula, . 20 Yorkshire, Ireland. Ireland, Yorkshire, &c. Yorkshire, Fermanagh. . 72 Gervillia? . 2 luoceramus ? 4 Ireland. 1 Ireland. Pecten, 3 Yorkshire, Ireland. Posidonomya, 8 Fermanagh, Derbyshire. Pterinea ? 1 Tyrone. PTEKONITES, 5 Ireland. DLMYARIA. Anatina ? 2 Ireland. Anodontopsis, 1 Ireland. Area, . . 7 Ireland, Derbyshire. Cardmia (unio), Cardiomorpha, 5 4 England, Wales, Scotland. Ireland, Yorkshire. Conocardium (Pleuroi hynchus), . 9 Ireland, Yorkshire, Derbyshire. Corbis? . . . . 1 Ireland. Corbula? . 1 Scotland. 3 Yorkshire, Ireland. Cypricardia, 9 1 Ireland, Yorkshire, Northumberland. Ireland. Dolabra ? 6 Ireland. Donax ? 1 Ireland. Edmondia, . . 13 Ireland, Yorkshire. Leda, Leptodomus, 8 3 Ireland, Derbyshire, Northumberland. Ireland, Yorkshire, Lanarkshire. 2 Derbyshire, Northumberland. Yorkshire, Ireland. Lucina ? 3 Lutraria ? 1 Ireland. Mactra? 2 Ireland. . 16 Ireland, Yorkshire. Myacites, 7 6 Ireland, Derbyshire. Lanarkshire, Salop. Mytilus, 3 Ireland. Nucula, . 14 Armagh, Northumberland, Salop. Pandora ? . 1 Ireland. Pleurophorus, 1 Weardale, Durham. Psammobia ? 1 Ireland. Pullastra ? . 2 Ireland. Sanguinolites, . 15 Ireland, Northumberland. SEDGWICKIA, 7 Ireland. Solemya, 1 Northumberland, Ireland. Teredo ? 1 Ireland. OEGAKEC EEMAINS CAEBONIFEEOUS SYSTEM. 231 Unio, Venus? Salop, near Edinburgh. Northumberland, Yorkshire. Conularia, PTEROPODA. 1 Lanarkshire, Bristol. GASTEROPODA. Capulus, . . 9 Ireland, Yorkshire. Cylindrites ? 1 Derbyshire. Dentalium, . , 2 Ireland, Westmoreland. DIRINUS, t 1 Ireland. Euomphalus, j 21 England, Wales, Ireland. Lacuna ? 1 Ireland. Littorina, 1 Ireland. Loxonema, . ( 14 Ireland, Derbyshire, Yorkshire. Macrocheilus, . 16 Ireland, Yorkshire, Derbyshire. Melania ? ' 1 Kendal. METOPTOMA, 5 Derbyshire, Yorkshire. Murchisonia, 9 Ireland, Yorkshire, Derbyshire. Natica, t 14 Northumberland, Yorkshire, Ireland, Salop. Nerita, . 2 Bristol, Ireland. Patella, , 8 Yorkshire, Ireland. PHANEROTLNUS, ( 3 Yorkshire, Ireland. PLATYSCHISMA, Pleurotomaria, Trochus, - 7 38 2 Ireland, Derbyshire. Yorkshire, Ireland, Derbyshire. Yorkshire, Derbyshire. Turbo, 4 Yorkshire, Ireland. Turritella, 8 Lanarkshire, Westmoreland. SaloD. NUCLEOBKANCHIATA. Bellerophon, 23 Porcellia, 4 Yorkshire, Ireland, Derbyshire, Lanarkshire, Yorkshire. CEPHALOPODA. Actinoceras, . 1 Cryptoceras, 2 Goniatites, 56 Dumfriesshire, Ireland. Derbyshire, Yorkshire. Yorkshire, Ireland, Derbyshire. Nautilus, 40 Orthoceras, 33 Ireland, Dumfriesshire, Derbyshire. Yorkshire, Ireland. POTERIOCERAS, Dumfriesshire, Yorkshire. TRIGONOCERAS, 2 Ireland. FISHES. Acanthodes, Amblypterus, . 4 Asterolepis, . 1 Near Edinburgh. Near Edinburgh, Ireland. Armagh. ASTEROPHTYCHIUS, 3 Armagh. Carcharopsis, . 1 CENTRODUS, . 1 Armagh. Lanarkshire. 232 UPPEE PALEOZOIC STEATA. CHEIRODUS, 1 Derbyshire. Chelyophorus, 1 Ireland. CHOMATODUS, 5 Armagh, Bristol. CLADACANTHUS, 1 Armagh. CLADODUS, 10 Armagh, Bristol. CLIMAXODUS, 1 Derbyshire. Coccosteus, 1 Armagh. Cochliodus, 5 Armagh, Bristol. Coilacanthus, 1 Halifax. Colonodus, 1 Armagh. Cosmocanthus, 1 Armagh. Cricacanthus, 1 Armagh. Ctenacanthus, 10 Armagh, Bristol, Dalkeith. Ctenodus, 3 Yorkshire, Manchester. Ctenoptychius, 8 Armagh, Glasgow, Manchester. DIPLODUS, 2 Lancashire, near Edinburgh. Diplopterus, 1 Yorkshire. Dipriacanthus, 2 Armagh. Eurynotus, 2 Near Edinburgh. Glossodus, 2 Armagh. Gyracanthus, 5 Scotland, Yorkshire, Wales, Ireland. Gyrolepis, 1 Lanarkshire. HELODUS, 11 Armagh, Bristol, Lanarkshire. Holoptychius, Homacanthus, 9 2 Near Edinburgh, near Glasgow. Armagh. 1 Draperstown, Ireland. Lepracanthus, 1 North Wales. Leptacanthus, 2 Armagh, Derbyshire. Megalichthys, 2 Leeds, Glasgow. Nemacanthns, 1 Armagh. Onchus, 6 Armagh, Bristol. ORACANTHUS, 4 Armagh, Bristol. 9 Armagh Bristol. Orthacanthus, 1 Leeds. Osteoplax, 1 Ireland. Palaeoniscus, PETALODUS, PETRODUS, 7 1 Near Manchester, near Edinburgh. Armagh, Derbyshire. Derbyshire. PHYSONEMUS, 2 Armagh. PLATYCANTHUS, 1 Armagh. Platysomus, PLECTROLEPIS, 2 1 Near Edinburgh, Leeds. Lanarkshire. PLEURACANTHUS 2 Leeds, Dudley. PLEURODUS, 2 Lanarkshire, Reeabore. PtECILODUS, 8 Armagh, Lanarkshire. POLYRHIZODUS, 2 Armagh. PSAMMODUS, 4 Armagh, Bristol. PSAMMOSTEUS, 2 Ireland. Ptycacanthus, Pygopterus, 1 3 Near Edinburgh. Near Edinburgh. RHIZODUS, SPHENACANTHUS 1 1 Near Edinburgh. Near Edinburgh. TRISTYCHIUS, 2 Lanarkshire, i ermanagh. URONEMUS, 1 Near Edinburgh. PARABATRAOHUS, REPTILIA. 1 Lanarkshire ? OEGANIC EEMAINS CAEBONirEEOIJS SYSTEM. 233 The carboniferous system may now be compared in respect of its various groups of life with the older groups of the palaeozoic strata. Taking 1,000 for the general numerical term of comparison, we find the following proportional numbers of species in the several groups : Proportion to Proportion to 1,000. 1,000 Plants. Plants 286 176* omitted. Amorphozoa 1 1 Foraminifera 3 3 2 Zoophyta 114 70 85 Echinodennata 127 79 96* Annelida 169 11 Cirripedia Crustacea 36 22 27 Insecta 32 2 Bryozoa 53 33 41 Brachiopoda 191 117 143 Monomyaria 116 71 86 Dimyaria 166 102 124 Pteropoda 1 1 1 Gasteropoda 197 121 147* Cephalopoda 137 85 103 Fishes 174 107 130 Eeptilia 1 1 1 Aves Mammalia Here we find, in accordance with the preceding groups, zoophyta", brachiopoda, gasteropoda, and cephalopoda numerous ; but Crustacea have lost their importance, brachiopoda and fishes are at least rivalled by the gasteropoda, while echinodermata have sprung up to over- match the zoophyta, and dimyaria become numerous. The largest group of all is formed of land plants. If these be omitted, the numbers for the other classes may be more fairly compared with those given in preceding tables. 234 TIPPEE PALEOZOIC STRATA. CARBONIFEROUS SYSTEM. 109 107 Pecopteris aquilina. 109 Neuropteris Loshii. 108 Sphenopteris HseninghausiL 110 SphenophyUum dentatum. Ill Annularia brevifolia. CAEBONIFEBOTTS FOSSILS. 235 112 Calamites Suckovii. 113 Calaraites cannseformis. 114 Lepidodendron crenatum. 115 Lepidodendron elegans. 236 UPPER PALAEOZOIC STRATA. 118 116 Walchia SchlotheimiL 117 Walchia hypnoides. 118 Sigillaria pachj' derma. 119 Stigmaria ficoides. CABBOKIPEBOTTS FOSSILS. 237 125 120 Amplexus coralloides. 122 Cyathophyllura regium. 123a Cross section of a cell- 121 Clisiophyllum turbinatum. 123 Lithostrotion basaltiforme. 124 Chaetites depressus. - * Q_, : ,^- 125 Cyathocrinus planus> 124 124aSyringoporageniculata. 238 UPPER PALEOZOIC STBATA. 128 132 126 Platycrinus laevis. 128a To show the plates. 131 Phillipsia pustulata. 127 Taxocrinus nobilis. 129 Actinocrinus polydactylus. 132 Limulus rotundatus. 128 Taxocrinus egertoni. 130 Pentremites ellipticus. 133 Limulus anthrax. CAEBOFIFEEOTJS FOSSILS. 239 136 134 Fenestella membranacea. 134 abcde Magnified view. 135 Ptilopora flustriformis. 135 a Magnified view. 136 Producta gigantea. 137 Producta pugiUs. 240 UPPEB PALAEOZOIC STBATA. 138 Producta punctata. 14 Spirifera glabra. 143 Spirifera striata. 139 Producta martini. Jg tS^rSdatt 144 Orthis resupinata. CABBONIFEROUS FOSSILS. 241 145 148 149 145 Terebratula eacculus. 147 Rhynconella pleurodon. 146 Rhynconella acuminata. 148 Pleurorhynclius minax. 149Posidonialateralis. K 242 UPPEE PALEOZOIC STEATA. 150 Edmondia snlcata. 152 Phanerotinus cristatus. 151 Euomphalus pentangulatus. 153 Natica ampliata. 154 Pleurotomaria flammigera. 155 Bellerophon hiulcus. CARBONIFEROUS FOSSILS. 243 156 157 159 156 Bellerophon Urii. 157 Bellerophon costatus. 158 Orthoceras gesneri. 159 Orthoceras rugosum. 162 Goniatites listeri. 160 Orthoceras laterale. 161 Goniatites evolutus. 244 UPPER PALEOZOIC STEATA. 163 Goniatites striatus. 165 Ctenacanthus tenuistriatus. 167 Tooth of Megalichtliys Hibberti. lt>4 Nautilus sulcatulus. 106 Holoptychius Hibberti. 168 Ichthyocoprolites. PEEMIAN SYSTEM. 245 PERMIAN SYSTEM. It has been shown that the consolidated deposit of coal was subject to the effects of a very general disturbance of igneous agency from beneath, and that in this manner the whole arrangement of those deposits was altered, many parts of the bed of the sea being uplifted to form dry land. In the large but very irregular area left between these islands of carboniferous strata, the sea began to deposit lime- stones commonly charged with magnesia, sandstones remarkably coloured with red oxide of iron, and clays and marls of red, blue, and white colours ; the whole series being, in general, far from rich in organic remains, seldom traversed by metallic veins, and not so much dislocated by faults as the older strata. Generally, its stratification is unconformed to that of the subjacent coal measures, on whose ele- vated edges, faults, and dikes, its planes rest level and undisturbed. In the composition of this group we find traces of all the various operations of the sea; limestones crystallized, compact, brecciated, conglomerated, and earthy, full of magnesia, or containing carbonate of lime with little or no admixture, locally rich in organic remains, but frequently devoid of them ; sandstones coloured red, blue, or white, in stripes and spots, fine grained, coarse grained, or full of innumer- able pebbles, derived from primary rocks ; clays and marls of many various hues; the limestones locally productive of the remains of saurians, fishes and shells, the sandstones and clays occasionally containing plants, but over large tracts wholly destitute of them. These organic remains are principally analogous to those of the carboniferous system, but partly to those which occur in the more recent deposits, and the whole series, though separated from both, offers by many resemblances besides its intermediate position, a natural transition from the one to the other. In England, supposing all the limestones and red sediments mineralogically related to them to be present in one section, we should have, reposing unconformably on the coal strata, the following classification, beginning from above: f Purple coloured marls below the lias, j Alternations of red and bluish white marls, 4. Series of coloured I . with layers and nodules of gypsum. M an mn J mar l s I Thin layers of argillo- calcareous stone. IC ) | Red and bluish marls with gypsum and beds L of rock salt. I 3. Variegated red and {Red and white sandstone, mostly fine grained, ^ white sandstone -. and often impregnated with salt. (Poikilite of Conybeare.) (^Red conglomerate, full of pebbles of older rocks. 246 TIPPER PALEOZOIC STRATA. "2. Magnesian limestone. PALEOZOIC Red and white marls. Thin bedded compact limestone, with very little magnesia and few organic remains. Red and white marls and gypsum. White, yellow, or reddish magnesian lime- stone in thick beds, crystallized, compact, or earthy, often full of sparry cavities, and containing marine organic remains. Marl slate, in thin layers, occasionally en- 1. Yellow or purple sand j and sandstone and-! marl f closing fishes. [An extremely variable series of sandstones, sands, and clays, of various colours, ir- regular thickness, and much local diver- sity of character. Plants like those of the coal measures. In the former edition of this treatise, the composition of which was begun in 1830, all these strata were, in conformity with the views of Conybeare and Buckland, treated as one "system," called from its productiveness in salt the " saliferous," from its peroxidated aspect the "red sandstone," and from its variable tints the "poikilitic" system. The common characters by which it was so The Permian strata superposed and unconformed to the coal measures (Yorkshire). e Red marls. d Upper (non-magnesian) limestone. c Gypseous red and pale marls. b Lower (magnesian) limestone. a Lower red sandstone (Rotheliegende). united were mineral affinity, interlamination and mutual conformity of the strata, dissociation from the strata below and from those above. These characters still retain their force, but others have been placed in strong light, which render it desirable to divide this great red series PEBMIAtf SYSTEM. 247 into two parts, the lower of which presents more of palaeozoic, the upper more of mesozoic affinity. In fact, the study of their organic remains has made great progress since, in the former edition, we remarked the superior resemblance of the fauna and flora of the lower part of the series of strata to the corresponding tribes of the subjacent coal measures, and the greater analogy in this respect between the upper parts and the oolitic series. " The general result of an examination of the conchifera of the saliferous system, is that in the upper strata a general analogy to the oolitic strata can be recognized by tne trigoniae, plagiostomata, ostrseae, &c., and in their producta? and spiriferse the lower strata as distinctly claim affinity with the carboniferous limestone."* The view thus announced became more clear with time. The consequences of it on the classifications of English strata were ex- pressed cautiously in 1837,t and positively affirmed in 1840J and 1841 as part of a general scheme. After some hesitation, || Sir E. Murchison's investigations satisfied him of the truth of this view : and while registering the results of his great survey of Russia, founded, in harmony with it, the "Permian system,"!" now universally accepted as the uppermost member of that great Paleozoic series, which owes to the same hand many of its foundation stones. By this consent of geologists to an important change of classification, they have in fact affirmed as a principle, that it is by groups of associated organic forms, indicating life periods, that the chronology of the ancient world is to be measured and arranged. The collective character of the Permian system, then, is in its organic remains ; the plants which occur in its lower red sandstone are analogous to, if not identical with, those of the coal strata ; the shells and radiaria and bryozoa of the calcareous beds resemble those of the mountain lime- stone. But when, as often, indeed frequently, happens, these fossils are few and rarely to be seen, it is difficult to separate the sandstones of the Permian from those of the Triassic group a difficulty which is even now meeting the government geological survey on the borders of Derbyshire and Cheshire, and in the interior of Warwickshire. This difficulty will probably be overcome by the untiring zeal of the excellent field geologists who have been trained on this survey. But it deserves to be pointed out as an example of what frequently occurs an example of some want of exact contemporaneity in the marked changes of mineral deposits, and the marked changes of organic life. We have already seen, in the case of the transition from Silurian to old red deposits, that bands of this red deposit are interposed among * Encyclop. Metrop. Geology, ch. ii. p. 615, et seq , published 1833. t Treatise on Geology Cabinet Cyclop., vol. i., p. 189. See also Brown's Lethsea Geol. of the same year. t Penny Cyclop "Palaeozoic." Paleozoic Fossils of Devon and Cornwall. || Address to the Geol. Soc., 1842. f Geological Proceedings, 1842 ; and Geology of Russia, 1844. 248 TJPPEB PALAEOZOIC STKATA. the groups of upper Silurian life. In the case now before us, bands of red and blue trias-like sandstones and clays, with gypsum, are interposed among the strata which yield the Permian forms of life. In each case the change in mineral sediments is manifested in a given area of the ancient sea, before, in that sea, the great and characteristic changes of marine life occurred. But in the still earlier case noticed on the western flank of the Malverns, we found sediments of a lower Silurian type poured into a sea rich in forms of the upper Silurian age a return of the old sediments to a basin which it seemed they had deserted. It is, however, merely a want of exact contemporaneity which is remarked ; on a great scale, it cannot be doubted that there is some real mutual dependence, some real coincidence not indeed of epochs, but certainly of periods between the changes of physical condition and the revolutions of organic nature. Range of the Permian System in England. Of the beds included in this arrangement, the calcareous strata are perhaps the least extensive, yet, as usually happens, they are most regular and continuous in their ranges, and most consistent in characters, and afford the best data for the classification of the others. By looking at a geological map of England, the extent of the range of magnesian limestone may be observed from the north side of the Tyne uninterruptedly to the Tees, between which river and a place called Thornton Watlas, it is known only in a few points, though probably it exists continuously beneath the superficial accumulations of gravel. From this point to Bilborough, near Nottingham, its course is un- interrupted. Below it, in a narrow irregularly parallel tract on the west, repos- ing on all the members of the coal formation indiscriminately, runs the lower series of sandstones and marls ; above on the east, through Yorkshire and Nottinghamshire, ranges the conglomerate red sandstone, and upon this lies, through Durham, Yorkshire, and Nottinghamshire, the Mesozoic series of upper coloured marls and gypsum. Cumbrian District. On the western side of the summit ridge of the north of England, the vale of the Eden is filled by the new red sandstone formation, consisting principally of coarse or fine grained red sandstone, and red marl above, with, in one place, a remarkable series of conglomerate, or rather brecciated beds at the bottom, and in another a distinct deposit of magnesian limestone. The former is seen at Kirkby Stephen, in the angle between two lines of dislocation, and affords a very instructive point of comparison with an analogous deposit in Somersetshire, known by the name of millstone. It has a PEBMIAtf SYSTEM ENGLAND. 249 basis of red sandstone almost entirely filled with angular fragments of the neighbouring limestone strata ; it is disposed in vast unequal beds, with large distant joints almost invariably ranging north and south, lies with a dip to the east between the lines of two dislocations of the carboniferous limestones, to the violence accompanying which its own production was probably owing. It is not in general mag- nesian, yet some yellow beds contain that substance, and^hus we are led to refer its" production to the date of the lower parts: of the magnesian limestone. No further trace of beds analogous to the magnesian series of Yorkshire and Durham occurs, in the westward extSision of the new red sandstone group, round the Cumbrian mountains, till we reach Whitehaven, where magnesian limestone and conglomerate, lying in red sandstone, are sunk through in the coal pits, and seen in the high cliffs against the sea towards St. Bee's Head. From Professor Sedg- wick's examination of this district we learn that the section here presented is more closely similar to that of Yorkshire than was pre- viously supposed, and that the following groups are uniformly laid upon the coal system : 3. Variegated red sandstone of St. Bee's Head. !Red marl and gypsum. Magnesian limestone, sometimes replaced by or alternating with magnesian conglomerate. Magnesian conglomerates, analogous to those in the vale of Eden and varkms parts of Yorkshire. /'Coarse reddish sandstone of great thickness on the whole unconformed 1. < to the coal measures, but also in part unconformed to the rocks I. above, which lie in its hollows. In their northward extension beyond the Solway Frith to Dum- friesshire and Galloway, the red sandstone strata do not exhibit any traces of magnesian limestone. Midland Counties. Beyond the southern termination of that rock, near Nottingham, the variegated red sandstones and coloured marls spread themselves over the whole area between Leicester, Warwick, and' Worcester, on the one side, and Shrewsbury, Chester, Liverpool, on the other, and extend northwards to Manchester, Leek, and Ash- bourn. Yet in all this immense area, except near Manchester, we nowhere find any deposits strictly analogous to the magnesian lime- stone. The South Lancashire coal field is bordered in places by magnesian limestone and red marls, containing axinus and other Permian shells. In this neighbourhood also, as at Worsley collieries, we appear to recognize the lower red sandstone of Yorkshire, in several places overlying the coal beds, and it is probable that further ex- amination may extend these points of agreement. Near Shrewsbury, likewise, the coal strata are succeeded by what appears to correspond 20 UPPER PALEOZOIC STRATA. to the lower red sandstone, and upon this lies an often trappoid or magnesian conglomerate. The South Staffordshire field certainly, the North Staffordshire probably, is margined by Permian con- glomerate. Continuing our survey down the Yale of Severn, we find reason to reckon the trappoid conglomerate which overlies the coal of Abberley, and abuts against the syenite of Malvern as of the same Palaeozoic age, as suggested in our survey of that district (1842 et seq).* South of England. South of the Malvern hills, the variegated sandstones and marls, the latter predominating, pass down the Vale of the Severn, fill up the winding intervals of the dislocated carboni- ferous limestone, partly cover the coal basins of Somersetshire, spread in the vales of the Parret and the Exe, and reach the sea at Exmouth. The only parts of this extensive range where magnesian rocks ap- pear distinctly, is amongst the limestone and coal tracts of Somerset- shire, and South Gloucestershire. Along the sides of Mendip mag- nesian conglomerates of considerable extent separate the limestone from the red sandstone, and produce the ores of zinc ; a similar de- posit, in similar relation to the older limestone, appears along the Avon below Clifton, and at Radstock and other places it is pierced in the collieries, at or near the bottom of the new red sandstone, and receives the name of millstone. Conglomerates of a very singular, even por- phyritic, character occur near Exeter, in the lower part of the varie- gated sandstone and marls ; and from a general review of the whole subject, Professor Sedgwick classes the conglomerates of Exeter, Somersetshire, and Shropshire, with the lower or conglomerate por- tion of the magnesian limestone of the north of England. The red conglomerate of Exeter is by De la Beche ranked with the rothe- todteliegende. From this view of the subject, which is usually adopted, it would appear that the difference of the Permian system in different parts of England, arises rather from the limited continuity of the beds, than from any great variation in their quality or relations. The series is perhaps nowhere more complete than in the interval between the Wharfe and the Dun, yet even here several beds are deficient. The marl slate and conglomerate limestones are better studied in Durham, the upper limestone in Yorkshire and Derbyshire ; the lower red has the largest range, and is in fact, in England, accompanied by magnesian conglomerate, the most extensively distributed deposit. Ireland. In Ireland the Permian beds are very limited; but about the Lough of Belfast they are well exhibited, magnesiferous and calcareous, with a few Permian fossils. * Memoirs of Geol. Survey, vol. ii., part 1. Ramsay (1854) has suggested that the singular phenomena noticed in this rock may be best met by supposing its masses to have been transfixed by ice. PEEMIAN SYSTEM EUEOPE. 251 Permian System of Europe. General View. We are now at liberty to consider the characters of the Permian system as they appear in the other parts of Europe, which have been accurately examined by geologists. This compari- son is much facilitated by the mutual understanding now so general between English and foreign observers, and the subject is made fa- miliar to our countrymen by the published inferences of Sedgwick and Murchison. In the greater part of the region on either side of the Rhine, beds corresponding to the magnesian limestone of Eng- land are entirely unknown. It is chiefly along the line of the south- western face of the Thuringerwald, prolonged to the north-west as far as Miiriden, in the drainage of the Weser, along the southern and eastern borders of the Harz, and on the north-west side of the slate formation connected with the Erzgebirge, in the drainage of the Elster, that the zechstein and rauchwacke represent on a greater scale the yellow magnesian and upper laminated limestone of the north of England. They have been thus placed in apposition by King* Thuringian Permians. Stinkstein. Rauchwacke. Dolomit. Zechstein. Mergel-schiefer or Kupfer Schiefer. Todte-liegende. North of England Permians. Crystalline and other limestone. Brecciated limestone. Fossiliferous limestone. Compact limestone. Marl slate. Lower sandstone. This table, however, is deficient of the upper members. In the great Permian region of Russia, Murchison has had ample opportunity of studying this remarkable group of strata. It is there apparently, or for the most part, conformable to the older carbonifer- ous system ; contains gypsum, salt, and copper ; consists of grit, sandstones, marls, conglomerates, and limestones ; and contains one group of animal and vegetable life, the past and feeble, but still real representative of palaeozoic periods. Amidst the many varieties of sequence amongst the redder rocks, it appears to be recognized that " limestones, often interstratified with much gypsum, prevail toward the base of the Russian deposit. f" The forms of Permian life extend upwards above these calcareous portions, so that in completing the system, some part or the whole of the superincumbent red sandstones or conglomerates may properly be included. This inference has a bearing on Germany and England ; in both countries the red sandstones and conglomerates above the magnesian limestones may perhaps be divisible indeed this has been already * Permian Fossils, 1850. t Murchison, Siluria, p. 295. 252 UPPER PALAEOZOIC STRATA. done by Murchison into upper Bunter, belonging to mesozoic, and lower Bunter, containing sometimes plants of the palaeozoic age. This adds another illustration of the caution required in employing and weighing the relative value of mineral and organic analogies. Remarks on certain Members of the Permian System in England. Tariegated Sandstones and Clays. It will be useful to describe more particularly the general characters of the terrace of magnesian limestone, and its associated strata, which occupies so remarkable a range in the north of England. The table already given will explain the relation of the several members of this group, and we shall at present confine our attention to the calcareous portions. The most ample details on every point will be found in Professor Sedg wick's paper in the Geological Transactions. Marl Slates. Immediately above the lower red sandstone in the excavation for the Stockton Railroad, were found in ascending order, (1.) thirty feet of light-coloured siliceous sandstone in thin beds, alter- nating at the top with blue calcareous slate ; (2.) nine feet of yellow calcareous shale and marl slate, some of the beds incoherent and sandy. In this marl slate, about two feet above the sandstone, were found many impressions of vegetables (ferns) and fishes of the genus pal- seothrissum. The higher and more compact beds also contained pro- duetae, spiriferae, and terebratulse. The shales or marls of this series are sometimes highly bituminous. (3.) Twenty feet of thin calcare- ous beds with marly partings. These slaty marls and limestones have a very irregular extent even in Durham, and are imperfectly trace- able in Yorkshire. They are perhaps best exhibited about Kip- pax, (very thin), at Garforth Cliff, on the road from Leeds to Selby, where they are full of axinus obscurus, and contain a spinose species of monotis. Deposits somewhat analogous are described by Professor Sedgwick near Bolsover. Little or no magnesia is found in this part of the series. 170* (2), Yellow magnesian limestone resting on worn surface of (l)the Rotheliegende. 170* Section at Knaresborough. BEMABKS ON PERMIAN SYSTEM IN ENGLAND. 253 Yellow magnesian x,imest however, is that among the older of the primary strata the remains of plants and animals do not occur ; and it is probable that the living wonders of nature were not then in existence. It is, indeed, maintained that such remains would be wholly destroyed in the rocks by the operation of such a heat, and this opinion may be supported by many strong analogies. But as marine organic remains do occur, though rarely, in the midst of the Cambrian group, (Llanberris,) and become numerous in and near the calcareous bands of the upper portion of that series, it appears safer to admit that the heat, or some other unknown condition of this early period, was unfavourable to organic existence in the sea. It seems almost demonstrated that at this period there was very little dry land raised to the surface of the globe ; for all the present continents were certainly uplifted at sub- sequent and successive epochs, and therefore land plants could not be abundant. Become Frequent in the Upper. But in proportion as the igneous agency found vent, in the same ratio as the mountains were uplifted, we find the organic reliquiae of the sea and of the land embedded in greater abundance. Objections to this Hypothesis Considered. It may be objected by those who see in the ancient effects of nature nothing but the result of the present measure of natural operations, that three-fourths of the globe are now covered by water, and that the depression of one large tract may have corresponded to the elevation of a smaller; and that remains of plants and animals may occur in the submerged portion of the crust of the earth, of higher antiquity than any of our elevated strata. This may be true ; and it may also be true, as some persons suppose, that stratified rocks full of organic remains occur beneath the granitic floor ; but as neither of these hypotheses can be proved or even examined, they must remain as mere speculation. Nor is it a probable speculation. For certainly the continually diminishing number of species, genera, families, and even classes of animals, as we retrace the series of Palaeozoic creations, leads us naturally and forcibly to the conviction that we are approaching at once to the earliest traces of life, as well as to the earliest traces of watery action. We cannot avoid the conclusion that the earth has 262 UPPEE PALAEOZOIC STEATA. passed through great physical changes, and that the present measures of physical effect are not directly applicable to the epochs of earlier nature. From such differentials we cannot obtain the integrals of the periods which have gone by. General Ground of Argument. In maintaining i\iQuni form character of the natural terraqueous agencies, and the constancy of their mode of action, all philosophers are agreed ; but, as in every other problem submitted to investigation, experiment, or observation, the conditions are to be determined before the rate and measure of geological results can be expressed on a scale of magnitude or number. In a science founded on observation, these conditions cannot be known beforehand, they are the very objects of which we are in quest, and our only mode of approaching them is by analyzing the effects which have been produced by the known laws of nature, operating under these, at first unknown, conditions. What is the object of an experimental investigation, in which first the law is given, and next the conditions are assumed, the result of their combined operation having been pre- viously defined? Greater E fleets of Heal in the Older Epochs. A history of the SUC- cessive revolutions in the state of the globe must indeed be founded on a survey of the chemical, mechanical, and vital phenomena, now pro- duced by the atmosphere, rivers, the sea, and volcanoes ; and all con- clusions concerning the intensity, duration, and extent of igneous and aqueous agencies, in past geological periods, must proceed upon an examination and estimate of these agencies in the existing periods ; but the ratio of their effects at different periods is to be determined by evidence, not assumed by conjecture. The results of examination of the organic remains in the several stjfata, and of the character and condition of these strata, according to their relative antiquity, leave no doubt of the vastly greater and more general influence which, in the older geological periods, the proper heat of the earth had upon all the operations of nature in the sea and on the land, an influence far more equable as well as more intense than that exerted by the solar rays, independent of the seasons, and coextensive with the globe. Surely, then, under these peculiar conditions, the laws of nature which are concerned in the operation, themselves invariable, must have operated on a greater scale, and perhaps with higher intensity, than that which now characterizes their effects. All the results depending directly on the quantity of communicated heat, as, for instance, most of the phenomena connected with the decomposition, reconstruction, and consolidation of rocks, must have been vastly increased in amount, and proportioned in extent to the universal diffusion of heat ; while the arrangements of organic life which we know to be adjusted to a certain limited range of temperature. EANGE AND PHYSICAL FEATUBES. 263 must have been proportionately affected . Until the mean temperature of the sea was reduced to a certain standard, the physical conditions to which organic life is restricted on our globe were not established ; but during these periods the inorganic forces of nature must have been especially active, and on a very great scale. Hence the vast thick- ness, the great degree of consolidation, the crystalline character, the almost universal extent of the primary strata ; hence the rarity of organic remains, until, by the accumulation of considerable thick- nesses of nonconducting earthy materials upon the bed of the ocean, the communication of heat from the interior of the globe was retarded, so as to be counterbalanced by that constant radiation from its surface, which is one of the conditions whereto the organization of plants and animals is adjusted. CHAPTER IX. LOWEB MESOZOIC STEATA. Range and Physical Features. We now enter, by an easy mineral gradation from the Permian rocks, the next great division of the strata the Mesozoic scries, which includes a large part of the group formerly called "Secondary." In the British islands, this mass of per- oxidated sandstones and clays shows itself a little on the north-east of Ireland, by the Lough of Belfast, on the coast of Antrim, and west of Lough Neagh, unconformed to the previously dislocated coal, limestone, and other older strata. The Marquis of Down- shire, searching for coal beneath it and the Permian strata, sunk near Carrickfergus through the new Red, and found it, as in Cheshire, productive of rock salt. It is in some places covered by green sand, but liassic strata appear on the Antrim coast. In Scotland, Red sandstones overlie the coal of Arran, and were thought by Murchison and Sedgwick to be of this age. More surely the sandstones of Dumfriesshire, on some of which, at Lochmaben, are the footprints of vertebrata, belong to the lower part of the Trias, and are continuous with the much broader area of new Red sandstones and marls, which fill the Vale of Eden, in Cumberland, sweep in a crescent round the coal and limestone of Allenby, Hesket, Lowther, and Shap, and lie on the depressed side of the great Craven fault, under the great escarpment of Cross Pell. On the opposite 264 LOWEB MESOZOIO STEATA. side of the Cumbrian mountains, from St. Bee's Head by Bavenglass and Dalton in Furness, this series of beds recovers its course, and, interrupted by the Bay of Morecambe, reappears in the low part of Lancashire, by Poulton, Preston, Ormskirk, and Liverpool. Here it expands so as to occupy a large breadth in the midland counties, from Chester and Shrewsbury on the west, to Manchester, Congleton, Newcastle-under-Lyne, Cheadle, Ashbourn, and Nottingham, on the east. From Nottingham a long continuous belt of these red rocks runs northward, resting nearly or quite in conformity on the Permian, which overlies unconformably the coal, millstone grit, and mountain limestone. This band, including the Vale of the Trent, and the vales of York and Mowbray, expires in the broad estuary of the Tees. Resuming our survey at Nottingham, we find the great area between that town, Leicester, Coventry, Warwick, Worcester, and Shrewsbury, filled with new Bed sandstone and marls, except where the subjacent coal measures stand up through them, nearly as they did stand up in the sea which receive the red sediments. (See p. 191.) From Worcester southwards, the Severn Vale is chiefly in new Bed, which, after winding round many sinuosities of the coal measures about Bristol, and the mountain limestone of Mendip, spreads in the rich vales of Taunton and Exeter, and occupies a great breadth of sea cliff in the mouths of the Teign, Exe, Sid, and Axe. Expanding from the main mass, patches of new Bed appear in the interior of Devonshire, in Barnstaple Bay ; in the cliffs of West Somerset and North Devon ; on the south side of the Welsh coal field about Bridgend ; in the Vale of Clwyd and Anglesea. In this long range, and in this large area, the new Bed sandstone is everywhere marked by comparatively gentle features, easily swell- ing undulations, relieved here and there by picturesque cliffs of sandstone, over a pleasant river, such as the Mersey above Stock- port, the Dee about Chester, the Don about Ashbourn, the Avon at Warwick. In no part of the island does the sandstone of this series make hills more than 1,000 feet above the sea, the more conspicuous in feature being the Hawkstone ridges of Cheshire and Nottingham Castle ; if, indeed, these be not really composed of Permian rocks, as the cliffs about Warwick have been conjectured to be. The marly parts of the new Bed are generally fertile, the sandy and pebbly parts less so, or even barren, as in some parts of Sherwood Forest. Types of the Series. Having inspected almost every part of this Poikilitic series, it appears to us that the best general type is to be found in the Vale of the Severn, where between Tewkesbury and Newent, in a breadth of 10 miles, we have the subjoined general series, with a total thickness of about 450 yards.* * * Memoirs of the Geological Survey of Great Britain, vol. ii., part 1. KAtfGE OF THE SEEIES. In a vertical section the beds may be thus separated 265 185 (ii Pale gray or greenish n?cf*J. 1 Red marl. k White sandy lamina. i 11 fl. marl. h KKUPKR SANDSTOKE. J?*d marl with gypsum. f H'/ute sandy layers. L; e lied marl. d 7?d onci white marls and sa.idstonet. C White sandstone. b /2^-i sandstones, marls, and conglo- viz '>; f3'at3. a Red conglomerate, full of f rap, old rocls-Cferuviun t) The several beds may be thus described in the order of their suc- cessive depositions : ra Pale greenish marls, differing only by the colour from the red series below. Above is the regular series of bone beds and lias. I Red marls. To Thin laminae and white sandstone, and greenish marls. Here not seldom are cubical sandstone casts, in cavities once occupied, it is probable, by rock salt crystals. i Red marls. h Sandstone, white, yellowish, or brownish, generally full of oblique lamination, indicating shallow water and currents, with fish teeth and bone, bits of coal, stems of plants. Alternating with these are pale blue shales, much resembling those of the lias, with small bivalve shells. This fossiliferous series makes a traceable band in the Red series ; its protoxidated sediments being derived from another direction possibly from the quarter which afterwards yielded the lias. g Red marls, with gypsum in the upper part. f Thin cellular quartz on beds and sandy marls. e Thick red marls. This is the main part of the series. (Calamites.) b LOWER MESOZOIC STRATA. d Several beds of thin White and Red sandstone, alternating with the argilla- ceous strata. c White sandstones, sometimes firm, but often soft, and in a peculiarly concre- tionary or lumpy state no fossils. b Sandstones and conglomerates, 200 to 400 feet. Red sandstones, often con- glomeritic with quartz pebbles, and interstratified with red sandy shales a fossil found at Broomsgrove. a Peculiar pebbly Permian conglomerate, of limited extent, on the eastern side of the Abberley and Malvern Hills, remarkable for the abundance of trap- pean masses included, (whence its title of trappoid conglomerate) especially in the Abberley district It is not specially allied to the beds above; may be thought unconformed to them ; perhaps may really be a Permian rock, of the age of the magnesian and trappoid conglomerates which oc- cur against the coal fields of Shropshire and South Staffordshire. It rises to the height of 985 feet in the Abberley Hills. Thickness, to 200 feet no fossils, except such as occur in the pebbles. In all other districts of England we find the Poikilitic series to consist, in the same manner, of thick red marls (d to m) above, often embodying gypsum, and thin laminated, whitish or greenish sand- stones (waterstone) and white and Red sandstones, generally resting on conglomerates (6 to c) below. The Keuper is not yet traced with certainty north of Warwickshire. The uppermost bed (m) is gene- rally found below the lias. The peculiar conglomerate (a) fails in the north of England, unless it be represented by magnesian conglo- merate, or Rotheliegende (Permian). The only district where de- tails of importance are added to the section in the Vale of Severn is the salt region of Cheshire. Mr. Ormerod finds in that district the total thickness of Red sandstones and marls to be at least 1,700 feet, of which the upper group, including the salt and gypsum, takes about 700 feet ; the middle group, containing laminated sandstones, called waterstone, 400 feet ; and the subjacent sandstones, mostly red, and partially conglomeritic, believed to correspond with the " Bunter sandstone " of Germany, 600 feet. Rock Sail. Mr. Holland's paper in the Geological Transactions, vol. i., describes the situation and mode of deposition of the rock salt in Cheshire. Cheshire unites with the southern part of Lan- cashire and the northern part of Shropshire into a great plain, fifty miles long from north to south, and about twenty-five or thirty wide. It is bounded on the east and on the west, and interruptedly on the south, by carboniferous ranges of hills ; and the internal area is divided by two ranges of rising ground into three minor plains, which serve to conduct the Dee, the Weaver, and the Mersey to the Irish Channel. The range of Delamere Forest on the west, and an undulated tract ranging nearly westward to Halton and Runcorn, define the drainage of the Weaver, and include the most abundant sources of salt. Scarcely any rock salt is found except in this limited OEIGIN OP THE SALIFEEOT7S SYSTEM. 267 tract. On approaching the estuary of the Mersey, the ridges which bound the plain approach one another at two points, and suggest the idea of the included plain having heen once a lake. The salt which lies under this plain is found to thicken, at least partially, toward the contraction of the valley ; it does not, however, lie beneath the whole surface of the low ground, nor indeed in one connected mass, but occurs in detached flattened masses of limited area. The rock salt of Northwich ranges north-east and south-west, and its breadth is about three-quarters of a mile. The upper bed is thickest on the north-west, and thins off towards the south-east. Two beds of salt at Northwich, &c. Three beds at Lawton. Rock salt, 84 to 90 feet. 42 yards marl, &c. Parting of \ R0 f 4 feet salt, marls, &c.j" 10 yards marl, &c. 12 feet salt. Rock salt, 96 to 117 feet, and more. 15 yards marl, &c. 24 yards salt. The upper bed has been worked through only at Northwich and Lawton. No marine exuvia3 occur over the salt, or in any way as- sociated with it. The purest part of the salt in the upper bed is about three or four yards above the bottom of the bed, and about four feet in thickness ; the purest part of the lower bed is twenty or twenty- five yards deep in it, and five or six yards thick, below which the salt becomes earthy as above. This is the part worked. The salt is not stratified, but divided into vertical prisms of various polyhedral forms, and different magnitudes, sometimes a yard or more in diameter. The sides of these prisms consist of pure white salt. Gypsum abounds in the marls associated with the salt, the most abundant variety being the fibrous kind. Mr. Holland supposes that what is now the salt field was once a salt water lake, separated from the sea by a natural dam ; that the evaporation of the water caused the precipitation of the salt, and that ifc was afterwards covered with the laminated marls. To ac- count for so much salt, he imagines that the sea might often over- pass the dam. Perhaps we may say that there was here a lake of salt water, whether left as a lagoon by the retirement of the sea, or by the ele- vation of the land, or formed by the influx, of streams which had no outlet ; that in this lake the deposit of salt went on gradually, and that at intervals violent floods filling it with muddy matter, this was precipitated with gypsum, but without salt, but that afterwards the water again subsiding, salt fell as before. If the floods came in from the sea, this might explain the correspondence in character of these gypseous marls, and those which elsewhere belong to the Keuper era. 268 LOWER MESOZOIC STRATA. Section at IVorthwich. No. yds. ft. in. 1 500 Calcareous marl. 2 *1 1 6 Indurated red clay. 3 210 * Indurated blue clay. 4 120 Argillaceous marl. 5 010 *Indurated blue clay. 6 *1 1 Red clay, with sulphate of lime irregularly intersecting it. 7 110 *Indurated blue and brown clay, with grains of sulphate of lime interspersed. 8 400 Indurated brown clay, with much sulphate of lime crystallized in irregular masses. 9 116 *Indurated blue clay laminated with sulphate of lime. 10 110 Argillaceous marl. 11 100 Indurated brown clay laminated with sulphate of lime. 12 100 *Indurated blue clay laminated with sulphate of lime. 13 *4 *Indurated red and blue clay. 14 400 Indurated brown clay, with sand and sulphate of lime irregu- larly interspersed through it. The fresh water (360 gallons per minute) finds its way through holes in this stratum, and has its level at 16 yards from the surface. 15 120 Argillaceous marl. 16 109 *Indurated blue clay with sand and grains of sulphate of lime. 17 500 Indurated brown clay with a little sulphate of lime. 18 016 * Indurated blue clay with grains of sulphate of lime. 19 210 Indurated brown clay with sulphate of lime. 20 25 ROCK SALT. 21 10 1 6 Layers of indurated clay with veins of rock salt (occasioned by water filtering) running through them. 76 1 9 22 36 ROCK SALT sunk into 35 or 36 yards. Rock salt is a frequent but not an exclusive production of the red marl and Red sandstone ; the mines of Wielitzka are in tertiary green sand, those in the Salzburg Alps in limestone of the oolitic period. By far the larger proportion of ordinary springs, from whatever strata they issue, yield chloride of sodium, sometimes in very large quantity, and it is important to know that bromine and iodine, which are stated to be always existent in the actual sea water, very gene- rally accompany the muriatic salts in common springs. This is most remarkably the case with bromine. (See Phil. Trans. 1830.) The rock salt of Cheshire is perhaps entirely devoid of bromine and iodine, though the brine springs of the same district are found to contain both. The reason of this may be, that the hydrobromic and hydriodic salts have not the same ratio of solubility as the chloride of sodium. Foreign localities. The distribution of the Poikilitic series in foreign countries is extensive, especially in France and Germany, where, mantling round, or resting against the mountain tracts of the Vosges, Schwartzwald, Odenwald, Spessart, Thuringerwald, and FOEEIGN LOCALITIES. 269 Hartz, the sandstones and marls contain a calcareous rock at present unknown in England, called the muschelkalk, which in some of its external characters, particularly its smoke-gray colour and association with marls, bears a considerable analogy to the upper layers of the magnesian limestones of England, but by the occasional abundance and general character of its organic remains, is strongly assimilated to our lias. In several districts, especially in Wurtemburg, the sandstones and marls contain organic remains, both animal and vegetable, which are entirely distinct from those yet known to belong to the older formations, but greatly resembling those of the has and oolites, so that the foreign localities supply us with links in the chain of geolo- gical facts which were wanting in England, and which were neces- sary to a true estimate of the relation of the saliferous system to earlier and later deposits. Salt which, as above explained, occurs in England in beds only in the variegated marls, is found on one or other side of the Rhine in every bed of the system. From these remarks it is evident that there is a great general re- semblance between the characters of the saliferous formation as it exists in Germany, France, and England ; but to make the differ- ences equally apparent, it will only be necessary to fix our attention upon two districts in particular, viz., the Vosges mountains, which range to the north-east parallel to the Rhine, and the district in the north-east of Upper Germany, adjoining the Thuringerwald and the Hartz mountains. The general succession of strata in the saliferous system round the Vosges mountains may be well seen on the road from Metz to Stras- burg ; and the minuter details of the beds have been ascertained by those eminent geologists, Voltz and Elie de Beaumont ; to the for- mer of whom we owe the discovery of most of the vegetable fossils of these rocks, and to the latter a valuable discussion of the relations of the formations. Between the bottom of the oolitic system and the top of the sali- ferous system occurs, about Luxemburg especially, a peculiar sand- stone, which has hardly been distinctly recognized in any other situation. Below this, in descending order, is the following series of strata : Section of the Vosges. 4. Variegated marls, Keuper of Germany, marnes irisees of France. Red, pale blue, greenish, &c., with gypsum occasionally interstratified, especially near the top, with beds of sand- stone of different kinds, containing plants of the families calamites, equisetaceas, lycopodiacese, coniferse, cycadese, &c., univalve and bivalve shells, remains of saurians and chelonida. In these coloured marls, above the middle, lies a regular bed (six 270 LOWEB MESOZOIC STEATA. to ten feet thick) of extremely compact magnesian, yellow limestone, without fossils, and under it, in several places, black schistose marls ; in this part, also, gypsum is especially abundant. In several situa- tions, thin bands of reddish limestone occur, alternating with anhy- drite. 3. Muschelkalk. Limestone, generally compact, of a light gray or smoky colour, with partings of marl, containing peculiar encrinites, with ceratites, plagiostomata, and other shells analogous to those of the oolitic system, and remains of reptiles. Near Luxemburg it is very thin, and may easily be mistaken for lias ; near Saverne it is much thicker, and more characteristic. Afc Bourbonne les Bains it is a true magnesian limestone. As before observed, it does not exist in England. 2. Variegated red sandstone. (Banter sandstein of Germany, gres bigarre' of France.) Extremely similar to the new Bed sandstone of England. This also contains, locally, abundance of organic remains, both animal and vegetable. 1. The strata above named rest, in some places unconformably, upon a vast thickness of Red sandstone, in general much coarser, and more like a conglomerate than the variegated Bed sandstone ; the pebbles of quartz, which it contains in abundance, appearing to be derived from the ruins of portions of the primary rocks of the range of the Vosges. The magnificent precipices down which the road descends to Saverne, among grand old woods and torrents, are formed by this rock ; and the resemblance which it bears to the old Bed sandstone conglomerate of Monmouthshire, is such as to bias the English geologist strongly in favour of that approximation. In other cases, and especially in hand specimens, this rock appears to resemble the coarse Bed sandstone of Dumfriesshire and of Penrith Beacon, and as these rocks certainly overlie the carboniferous series, this comparison may, perhaps, be exact. The northern part of the Vosges mountains being wholly composed of these grit rocks, and coal beds being found at many points in the same vicinity, the incumbency of the Bed sandstone upon the coal is satisfactorily proved. The lower part of this thick arenaceous group, which rests upon the coal series, is usually of a friable and fragmentary nature, con- taining admixtures of porphyritic masses, which strongly assimilate it to the Bed sandstone conglomerate of Exeter, and the Bed sand- stone, expressly so called, of the north of Germany. The upper part, also, gradually becomes finer grained, and more like the ordi- nary variegated Bed sandstone ; but as in several places this latter rock rests unconformably upon the other, we are justified in adopting the opinion of Voltz and De Beaumont, that it is a portion of the Bed sandstone series, almost peculiar to the Vosges mountains, and FOBEIQN LOCALITIES. 271 may, therefore, be characterized as the gres des Vosges. The lower part of it is regarded by Murchison as " Permian*." North-East of Germany. The north-east of Germany gives us the following section of the saliferous system : 3. Variegated marls (Keuper, marnes iristes) with gypsum, and the usual characters of the strata. 2. The muschelkalk, much as it occurs about the Vosges. It admits of subdivision into two, or, perhaps, three parts, which accord- ing to Hoffman, may be distinguished by their respective types of organic remains. 1. Variegated sandstone. (Bunter sandstein, gres ligarre'.) Below are zechstein and rothetodteliegende. The following table will show the relations of the three tracts : England. France. Germany. Variegated marls. Marnes irisees. Keuper. Muschelkalk. Muschelkalk. Variegated sandstone. Gres bigarre. Bunter sandstein. Gres des Vosges. With respect to organic remains, it may be sufficient to remark generally that they are found locally in abundance in all the members of the saliferous series in Germany and France, while hitherto they have scarcely appeared in England. Salt. It appears that the greater part of the salt beds of Germany occur in the muschelkalk, between Magdeburg and Osnabruck, and in the Valley of the Neckar in Wurtemberg. At Vic, Baden, and Lons le Saulnier, salt lies in red marl, along the north side of the Tyrolean Alps, in Red sandstone (Altenau, Berchtolgaden), and it is possible that the abundant salt-works on both sides of the Carpa- thians in Transylvania and Moldavia may be established on this series. The salt of European Russia (Strangways, in Geol. Trans.) is connected with the new Eed and Permian sandstone ; so most probably the salt amongst the sands (said to be red) of Persia, and in India between the Indus and Chellum, but regarding the deposits in Africa, New Holland, and North America, we desire further infor- mation. The salt of Cordova, in Spain, and various points along the line of the Pyrenees, appears to lie in green sand ; that of the Salz- burg Alps belongs to alpine limestone of the oolitic area, while in Sicily salt is found in sulphureous tertiary marl, and at Wielitzka it lies in tertiary strata containing a few shells. Circumstances attending the Origin of the Saliferous System. its Marine Origin. From the preceding statement we may confi- dently decide that the whole of the strata belonging to the saliferous 272 LOWER MESOZOIO STRATA. system were deposited in the sea around the previously elevated lines of older rocks. The mechanical aggregates of sandstone, and clays, and marls, do not in general show us those exceedingly fine lamina- tions and indefinitely numerous alternations of different materials which mark the coal deposits, they do not abound in such a multi- tude of spoils of the land, nor contain extended layers of the reliquiae of fresh water. Had he never known of the local accumulations of fossil plants in the Keuper, and variegated sandstones of the conti- nent of Europe, the English geologist might have consistently doubted whether inundations from the land had ever disturbed the regular operations of the sea during this period. To explain this irregularity of distribution of terrestrial plants, it may be supposed that inundations of the land happened only in particular places along the margin of that ancient sea, or it may be said that the inundations being general, the growth of plants was limited. With respect to the accumulations of the rocks themselves, equal difference of opinion may be indulged ; for if the remarkable absence, from the greater part of the area of the saliferous system, of any marine exuviae in the mechanical aggregates might favour the notion of the materials being wholly derived from the land, yet the mere fact of the extraordinary and connected extent, the remarkable uniformity of character of these extensive deposits, even where the more anciently elevated strata round which they were evidently formed are of en- tirely different nature, and their apparent independence of these boundaries of their surface, seem to prove either 1, that the mate- rials were collected by the action of the sea itself; or 2, that when brought into it by other agents, they were for very long times ex- posed to its equalizing action. This long action of the waves upon the particles of the siliceous and aluminous rocks and minerals which compose the mechanical aggregates and sedimentary deposits of the saliferous system, is also suggested by the amazing prevalence of the colour of peroxide of iron, which covers as a varnish so many of the particles ; and it is confirmed by the discoveries of the organic remains, since these are of such a nature as to prove that during the period when peroxides were so prevalent, the last types of the living creation of the carbo- niferous period came to an end, and were replaced by other tribes, which likewise finished their career and yielded to the more nume- rous races which fill the oolitic rocks. Salt and Gypsum. The salt and gypsum usually associated in this remarkable system present also their difficulties. Not that it is hard to suppose the waters of the ancient sea to have been so evaporated as to permit first the crystallization of sulphate of lime, and finally of muriate of soda. But in this case we should expect to find almost uniformly over the whole area regular strata of gypsum ORGANIC REMAINS. 273 below, and regular layers of salt above, while, in fact, we more com- monly find salt in great broad masses rather than beds below, and gypsum in scattered masses above. A general drying of the waters in which the saliferous system was deposited is plainly inconsistent with probability ; and we must have recourse to local causes, some- thing analogous perhaps to those which influenced the deposit of primary limestone. It may be conceivable that the solubility of muriate of soda in water is capable of diminution through the admix- ture of other substances in the liquid, or through the effects of great pressure, or of pressure and heat combined ; it may be maintained that the limited deposits of salt happened in separated lagoons of the sea, exposed to local desiccation, as perhaps in Cheshire. Lyell has still a different and less probable view of the subject. All these explanations assume that the salt was produced directly by mere crystallization, from waters almost perfectly analogous to those of the actual seas ; an assumption strongly confirmed by the recent discoveries connected with bromine and iodine. Further researches, both chemical and geological, must determine between these and other theories, and, in particular, we must be more exactly informed of the ancient hydrography of the salt dis- tricts, which, in almost every instance, must have been very different from their present topographical features. Organic Remains. The Poikilitic group yields in the British Isles very few fossils. In the sandy beds to which specially the name of Keuper was given, we find a few plants, shells, and remains of fishes ; and this small catalogue is augmented by the reptiles of Warwickshire and perhaps of Bristol (unless one of these localities belong to the Permian group). The sandstones of Dumfriesshire, Liverpool, &c., have yielded to Sir W. Jardine and others a large series of footprints of reptiles.* The bone beds of Aust lie at the base of the lias ; but Sir P. Egerton regards the organic remains in them as really Keuperian. PLANTS, . . Dictyophyllum crassinervium, near Liverpool. Echinostachys oblongus, Bromsgrove. Walchia hypnoides, Convallarites, MONOMYARIA, . Posidonomya minuta, DIMYARIA, . Pullastra arenicola, . FISHES, . . Dipteronotus cyphus,f Hybodus Keuperi, Warwickshire. Do. Shrewsbury Common, Salop, near Pendock. Near Pendock. Bromsgrove, inBunter Sandstein. Pendock, Burgehill, &c. * Ichno. Annan. t This is a homocercal fish, and thus contrasted with the Palaeozoic races, tut allied to the Mesozoic forms. 274 LOWEE MESOZOIC STEATA. The following are from the bone bed : Acrodus minutus. Ceratodus altus. curvus. daedaleus. disouris. emarginatus. gibbus. latissimus. obtusus. parvus. planus. REPTILIA, . Cladyodon Lloydii, . Labyrinthodon Bucklandi, . giganteus, . leptognathus, scutulatus, . ventricosus, Rhynohosaurus articeps, Thecodontosaurus, sp. . . Gyrolepis Alberti. tenuistriatus. Hybodus laeviusculus. minor. plicatilis. Nemacanthus filifer. monilifer. Saurichthys apicalis. near Warwick, near Leamington, Warwickshire. Guy's Cliff. near Warwick, Cullington. Leamington. near Warwick. Grinsill, Warwickshire. Rutland, Bristol. Leamington. The following are from the bone bed : Plesiosaurus costatus, Aust. Hawkinsii, Do. trigonus ? Do. Rysosteus, Do. ICHNITES,* . Actibatus Triassae, . Corncockle Muir, Dumfries. Batrichnis Lyellii, Green Mill, near Dumfries. Stricklandi, Dumfries. Cheirotherium Hercules, Tarporley, Cheshire. Kaupii, Lymm, Cheshire. Storeton Cheshire. Lymm. Annan. Chelaspodos Jardinii, . Dumfries. Chelichnis ambiguus, . Corncockle Muir. Duncani, . Do. gigas, Do. obliguus, . Do. plagiostopus, Do. plancus, Do. Titan, Do. Weston, near Runcorn. Herpetichnis Bucklandi, Corncockle Muir. Sauroplesius, Do. Saurichnis acutus, Dumfries. Beyond the British dominions, Europe yields a much larger, but still a limited series of life in the Triassic strata, none of the ' Jardine, Ichnology of Annandale. ORGANIC REMAINS SALIFEROTJS SYSTEM. 275 members of the group being absolutely void of organic remains. The following lists, drawn up in 1833, will furnish a general idea of this comparatively small flora and fauna : Table of the Organic Remains of the Saliferous System. The asterisk distinguishes such as are known to occur in other s PLANTS. Family and Name. Locality in Keuper. j^Jelkal ' Equisetum Meriani, . Neue Welt, near Basle, columnare, . . Wurtemberg, platyodon, . . Franken, in Wurtem. Calamites arenaceus, , Do., .... Mougeottii,. t'''' 1 ''* 1' ' ; ' ' ; ; ; -" '. ;/ '. rstems of strata. i Locality in Bunter E. Sandstone. Sulzbad, or Soultz. Wasselone, Mar- moutier. Marmoutier. Wasselone. Soultz, Wasselone. Soultz. Do. Do. Do. Do. Pecopteris Meriani, . Neue Welt. Taeniopteris vittata, . Neue Welt, Stuttgart. Anomopteris Mougeotti, . . . Neuropteris Voltzii, . . .... elegans, . Gaillardoti, ..... Luneville. Sphaenopteris myriophyl- lum, .... ..... palmetta, . . ..... Filicites Stuttgartensis, . Stuttgart, lanceolata, . . Do. scolopendrioides, . ..... f Pterophyllum longifolium, Neue Welt. Meriani, . . Do. -( Jaegeri, . . Franken, Stuttgart. enerve, . . Neue Welt. [ Mantellia cylindrica, .... Do. Convallarites erecta, nutans, . . . . . . Palaeoxyris regularis, ..... Echinostachys oblongus, ..... jEthophyllum stipulare, ..... Marantoidea arenacea, Stuttgart. Voltzia brevifolia, . elegans, rigida, acutifolia, . pterophylla, Do. Do. Do. Do. Do. Do. Do. Do. Do. Do. The names in this list are taken from M. Brongniart, who supposes the flora of the variegated sandstone system to be of a peculiar type. It is certainly very analogous to that of the succeeding or oolitic epoch, by its pterophylla and equiseta, but the genus Voltzia is perhaps peculiar to it. 276 LOWER MESOZOIC STBATA. FOLYPARIA. The absence of polyparia from the muschelkalk is one of the cha- racters by which it approximates to the lias. RADIARIA. Locality in Keuper. Locality in Muschelkalk. ains . Baireuth. Name. Ophiura prisca, Mun., . . Vosges Mountains, loricata, G., . . . Schwenningen. Asterias obtusa, G., ...... Marbach. Encrinus moniliformis, Mil., ..... General in this rock. Pentacrinus dubius, Gold., . . . . . ? Rudersdorf. ANNULOSA. Name. Serpula valvata, G., colubrina Locality in Muschelkalk. Baireuth. ? By its radiaria, amongst which no echinus is mentioned, the mus- chelkalk resembles the lias. Family and Name. CONCHIFERA. Locality in Keuper. Cardium pectinatum, v. Alberti, . . . Wurtemberg, striatum, Schl., ... Trigonia vulgaris, Schl., . Ludwigsburg, curvirostris, Schl., . Do., Schwenningen, sulcata, G., . . Villingen. pes anseris, Schl., .... Locality in Locality in Muschelkalk . Bunter Sandstone. Wurtemberg. Do., Gottingen. Weimar, Gottin- gen, JJCST berg, Baireuth, Wurtemberg. ~ ., fl2S? Gottingen, Mors- bach, Luneville. Wurtemberg. Marbach. Do. ' cardissoi'des, G., . . Isevigata, G., . . . . Goldfussii, v. Alberti, . . Mya musculoides, Schl., . Sultz on the Neckar, Weimar, Wurtem- berg, Upper Sile- sia, Poland, . Sulzbad. elongata, Schl., . Do., . . Wurtemberg, near Waldshut, Upper Silesia, Poland, Sulzbad. ventricosa, Schl., .... Wurtem., Luneville. mactroides, Schl., .... Marbach, Upper Si- rugosa, v. Alberti, Modiola minuta, G., lesia, Poland. Rottweil. Rottweil. Venericardia Goldfussi v. Alberti, . . . Rottweil. Saxicava Blainvillii, Hsen, ? Venus nuda, G., . . Mactra ? trigona, G., .. Area inaequivalvis, G., . Cucullaea minuta, G., . fGottinge n, Wur- 1 D ^ Marbach. Do. Freudenstadt. Villingen. OEGANIC EEMAINS SALIFEEOrS SYSTEM. 277 Family and Name. Plagiostoma lineatum, Schl., striatum, Schl., Locality in Locality in Keuper. Locality in Muschelkalk. Poikilitic Sandstone. TMorsbach, Michel- }w urt e m berg,. **$ 1^ reuth, Weimar. Very common. laevigatum, Schl., punctatum, Schl., . Avicula socialis, SchL, . subcostata, G., > lineata, G., Morsbach. . . . Gottingen, Gotha, Weimar, Baireuth, Toulon. Sulz on the Neckar, Very generally) Sulzbad, distributed, ) Domptail. Do., . . Wurtemb.jBaireuth. Do. Mesomyona. Bronnii, v. Alberti, . costata, . Posidonia Keuperiana, Voltz, minuta, v. Alberti, . Ostrea placunoides, Mun., subanomia, M., Villingen. Sulzbad. Swabia, Hall. Rottweil. Baireuth. Do. Do. difFormis, Schl., multicostata, M., complicata, G., decemcostata, M., . spondyloides, Schl., . Wurtemberg. Wurzburg. Baireuth, Villingen. Baireuth. Very general. Rottweil. pleuronectites, Schl., Bourbonne les Bains, Luneville. Pecten reticulatus, Schl., Alberti, G., . Gottingen, Gotha. Villin., Rudersdorf. Isevigatus, G., . Wurtemberg, Bai- reuth, Gotha. Brachiopoda. L Perna vetusta, G., . r Lingulatenuissima, Bronn, Terebratula communis,) Bosc., . . [i vulg.et subrot.Schl.) perovalis, Schl., sufflata, Schl., orbiculata, Schl., Spirifer, Sow, semicircu- laris, G., .. len, &c. Durrheim. Rottweil, . . Rottweil. f Gottingen, Wurtem- j berg, Luneville, | Bourbonne les l_ Bains, Toulon. Jena. Do. Near Jena. 278 LOWEB MESOZOIC STEATA. GASTEROPODA. Locality in Family and Name. Locality in Keuper. Locality in Muschelkalk. Poikilitic Sandstone. Calyptraea discoides, Schl., . . . Villengen. Capulus, or Pileopsis mi- tratus, G., . . . . . .Do. Dentaliumtorquatum,Schl. . . . Gottingen. laeve, Schl., . . $ . .Do., Alpirsbach, Bai- reuth. Trochus albertinus, G., . . .Rottweil. Turbo? dubius, Mun., . . - . Seewangen, Riedern, near Waldshut. ? giganteus, Schl., . ; . . Seewangen. Turritella obsoleta, Schl., . . . Weimar, Gottingen. deperdita, G., . . . . . Weimar. detrita, G., . Culmbach. scalata, Schl., . . . . Wurtemberg, Ruders- dorf. ? terebralis, Schl., .... Weimar, . . . Domptail, Sulzbad. Schoteri, Sulzbad. TBuccinum turbilinum, . Sulz on the Neckar, Wurtemberg, Seewan- gen, Rudersdorf. gregarium, Schl., . , . Rudersdorf. antiquum, G., . Sulzbad. CEPHALOPODA. Name. Locality in Muschelkalk. Nautilus bidorsatus, Schl., . Weimar, Rudersdorf, Gottingen, Wurtemberg, Lune- ville. nodosus, Mun., . . Franken. Ammonites, nodosus, Schl., . Weimar, Gottingen, Wurtemberg, Lorraine, Toulon, Tarnowitz. bipartitus, Gaill., . \ Luneville semipartitus, Schl., f L [villers. RhyncholitesGaillardotid'Orb., Jena, Gottingen, Wurtemberg, Luneville, Rehain- hirundo, Fauv., . . Wurtemberg, Luneville. These cephalopoda are characteristic of the muschelkalk. The ammonites belong to a section of that numerous genus, distinguished by peculiar sutures, and called Ceratites. See Von Buch's Essay on the subject of the sutures of ammonites. (Ann. des Sci. Nat.) CRUSTACEA. Name. Locality in Muschelkalk. Palinurus Suerii, Desm., . . Villingen, near Saarbruck. VERTEBRATA. Name. Locality in Keuper. Locality in Muschelkalk. SeidmannsdorfjNeuses, Sei- dingstadt, near Coburg, Baireuth. Teeth of Sharks, &c., . Wurtemberg, . . Wurtemberg, Rudersdorf. Phytosaurus cylindricon, Jaeg., cubicodon, Jseg., . Mastodonsaurus Jaegeri, Holl., Ichthyosaurus Lunevillensis, Plesiosaurus, . Boll. Do. Gaildorf. Wurtemberg, . . Luneville, Wurtemberg. Durrheim, . . . Wurtemberg, Baireuth, Rudersdorf. SALIFEKOUS SYSTEM FOSSILS. 279 Crocodilus, Rudersdorf. Large saurian, Luneville. Chelonia, Do., Bindlocher, and Lei- neckerburg. It is unnecessary to point out the obvious and almost universal difference between this last and any of those which represent the earlier Palseozoic life. Like the oldest of those rocks, so this the first of the Mesozoic groups is poor in all the forms of life. Those which do appear are generally analogous to, and often congeneric with, the more numerous groups of middle Mesozoic plants and animals. SALIFEROUS FOSSILS. 186 Ammonites (Ceratites) nodosus. 187 Avicula socialis. 188 Posidonia minuta. 189 Encrinites monilifoimis. 190 Trigonia vulgaris. 280 SALIPEEOUS SYSTEM FOSSILS. 191 192 191 Pterophyllum HeiningeriL 192 Voltzia heterophylla. MIDDLE HESOZOIC STEATA NEW BED SEEIES. 281 CHAPTEE X. MIDDLE MESOZOIC STEATA. Disturbances of the New Red Series. In England dislocations on a very extensive scale are but rarely exemplified in strata more recent than the coal measures. Several upward and downward movements of the land, and consequent great changes of level, certainly occurred. One long axis of movement is traceable in the Wealds of Sussex, another in the Isles of Wight and Purbeck ; but it appears that this part of the surface of the globe enjoyed a long and rarely interrupted immunity from those violent agencies which had previously shaken its strata into such disturbed positions. A few faults in the magnesian limestone range of Durham and Yorkshire, as along the line of the great whin dike through those counties, in the country between Doncaster and Ferry bridge, and south of Doncaster, may be mentioned rather as exceptions to the general rule, effected in some indefinite portion of the long period succeeding the deposit of coal ; and the curious parallel faults of Aust cliff on the Severn, which affect both the lias and red marl, deserve attention, in connection with the law formerly laid down of faults underlying depressed portions of strata. Neither on the continent of Europe are the dislocations of the saliferous system so remarkable as those of the older strata. In the Vosges mountains we have, however, a splendid example of a dislo- cation on a great scale, by which, in a direction north-east and south- west, the lower strata of this system (gres des Vosges) are thrown up into bold mountains, while the upper beds of the same system (muschelkalk and keuper) are left several hundred feet below the magnificent escarpment. In fact, it appears that this eruption hap- pened after the date of the gres des Vosges, and before the muschel- kalk and keuper were deposited. Unconformity and interruption of continuity between the varie- gated marls and the oolitic formation above are but local effects; parallelism of strata generally prevails between these contiguous systems, indicating freedom from general disturbance, and in some instances, especially in Somersetshire, the frequent changes of colour in the upper red marls, and finally the interposition of a purple or black marl, which is not more related to the lias than to the subjacent system, appear to show that even in the nature of the deposits there is no more decided difference between them than between any other successions of strata. 282 MIDDLE MESOZOIC STKATA. Oolitic System. The oolitic system of strata has for the most part its ranges parallel, and its declinations accordant to the saliferous rocks, and was deposited in the same marine basins. The general character of the rocks, and the nature of the organic remains are, however, extremely different, but the change from the one system to the other, though seldom to be called gradual, is accomplished by remarkable repeti- tions. In particular, the muschelkalk of Germany and France repre- sents or anticipates, even in mineralogical characters, but more de- cidedly in its suite of organic exuviae, the lias, which is at the base of the oolitic system. Through all the mass of the oolitic system, consisting of various limestones, clays, and sands, the most remark- able repetitions occur. The mass of lias contains beds very nearly approaching to the ferruginous inferior oolite; three or four separate beds of very similar oolite, several beds of sand and sandstone also remarkably analogous, and many thick strata of clay hardly distin- guishable except by their organic reliquiae, make up this vast argillo- arenaceo-calcareous mass, of which the top changes, by repeated introductions of green sand layers, to the real cretaceous system, as the bottom has been before shown to be partially connected with the saliferous group. The composition of this system varies much in different countries of Europe, according, probably, to the differences of depth of the original waters, proximity to land, to mouths of ancient rivers, &c. In consequence, while on the border of Switzerland it is almost wholly calcareous, in Westphalia and in England its limestones are much intercalated with clay, and occasionally with carboniferous sandstones and shales, hardly to be distinguished from those of the older coal strata. A remarkable absence of metallic substances is a character of the calcareous portions of this system (excepting the lias) in all its extent. The most distinct classification of the oolitic system will be ob- tained from the combined section of the English series ; for though the total thickness of the deposit is perhaps greater in the south-east of France and in Switzerland, the number of divisions is there less, the mass more uniformly calcareous, and the parts less characteristic. The oolitic system of England everywhere admits of the following mode of subdivision, though in some tracts particular groups are concealed by unconformity or entirely wanting. The groups are placed as they occur in nature, or the series is descending; the num- bers indicate the order of time : OOLITIC SYSTEM. 283 5. Wealden formation. 4. Upper or Portland oolite formation. 3. Middle oolite or co- ralline formation 2. Lower or Bath oolite formation. 1. Lias formation. A series of clays, sandstones, and limestones, mostly of fluviatile origin, and containing remains of land and fresh water animals and plants, deposited in estuaries or other local hollows of the really marine portion of the oolitic system. Calcareous, sometimes oolitic rocks, associated with green and irony sands, resting on blue clay, altogether marine deposits. When the Wealden formation is absent (as happens in the greater number of instances) this termi- nates the whole system, and graduates into the cretaceous rocks above. Consisting of oolite and other limestone strata, included in calcareous gritstones, and resting on blue clay and cal- careous gritstone: altogether marine deposits. Consisting of two or more strata of oolite, with other cal- careous beds, and alternations of sands and clays, which in particular districts enlarge themselves into real coal tracts. Altogether marine and littoral deposits. Consisting principally of argillaceous clays, more or less laminated, and including, especially in the lower part, layers and nodules of generally argillaceous limestone, and in the upper part bands and strata ferruginous, cal- careous, and arenaceous, which strongly resemble the bottom of the lower oolite formation. 5. Wealden formation of Kent, Sussex, and Hampshire. 4. Upper oolite forma- tion of Portland, Wilts, Bucks, Berks, &c. 3. Middle oolite | formation of ^ Oxford, g Berkshire, ^ Yorkshire, &c. A further analysis of these formations presents us with the follow- ing details : Weald clay. Thick blue clays, generally destitute of or- ganic remains, except in certain calcareous beds, which contain fresh water shells. Hastings' sands. Thick series of sandstones, with partings of clay, and subordinate beds of limestone, with bones of saurians, fluviatile shells, and land plants. Purleck beds. Blue clays and laminated limestones with fresh water and estuary shells. Portland oolite Oolite and earthy and compact lime- stones with marine shells, and layers of nodular chert. Shotover sand. Calcareous sand and concretions. Kimmeridge clay. Thick blue clay, bituminous, with sep- taria and marine remains, and especially in the lower part, bands of sandy concretions, thus establishing a gradation to the next system. Upper calcareous grit, with marine fossils. Coralline oolite, so named from two or three separate beds of irregular occurrence, rich in zoophytic exuviae. In the lower part the beds alternate with those of the next rock; all of them contain marine remains. Lower calcareous grit, with marine shells, graduating be- low into the Oxford clay. Oxford clay, with septaria, fossils, &c. ; the lower part a subordinate bed, called Kelloway rock, which is a calcareous grit, (rarely oolitic,) very rich in fossils. Blue clay dividing Kelloway rock from the cornbrash. A II 284 MIDDLE MESOZOIC STRATA. 2. Lower oolite -g "G formation in * ^ Gloucester- -0 'g shire, Ox- *S * fordshire, & g . Northamp- ^jg tonshke. ^ fc H ri 05 8 ^1 8 Forest marble group. Great oolite. Cornbrash limestone, a coarse, shelly rock of variable and small thickness, but remarkable continuity. Sand with concretions of sandstone and nodules of fissile arenaceous limestone. Coarse shelly oolite, in some places slaty. 1 Sandy clay or grit. I Blue clay of Bradford. {A calcareous and mostly oolitic rock, of variable thickness and changeable nature, the upper beds shelly, the lower sometimes laminated. Fuller's f A series of marls and clays with included earth < beds of soft marly or sandy limestones and group. I shells. f A coarse, often very shelly rock of limestone, T / irregularly oolitic, occasionally interlaminated n erior _| ^.^ ^^ especially in the lower part. I Ferruginous sand with concretionary masses of I sandy limestone and shells. Upper lias clay or shale, full of belemnites and other fossils, intercalated with or graduating to the sand above, and in some cases containing nodules and bands of limestone. Marlstone. A suite of calcareous, sandy, and irony beds, very rich in fossils, and much analogous to the lowest beds of the lower oolite formation. Lower lias clay or shale, full of fossil remains, interlami- nated with bands and nodules of limestone, especially in the lower part, where a collection of these layers consti- tutes the lias rock. Lias rock. A suite of laminated limestones, with partings of clay, blue, gray, and white, the former in particular containing gryphites and other shells; the latter usually devoid of organic remains. This rock is sometimes con- solidated into a united mass, and sometimes divided into separate portions. Bone bed, and blue, black, or purple marls, which cover the new red formation in the south of England. Range of Lias. The lias formation is observed on the southern coas't of England, at Lyme Regis, from whence, passing under the unconformable green sand of Blackdown, and surrounding the irre- gular elevations of carboniferous limestone in Somersetshire, it ranges uninterruptedly by Bath, Gloucester, Leicester, Newark, and Gains- borough, to the Humber. At this point the course of the oolitic system is very much narrowed by the over-extension of the chalk ; and at Bishop Wilton the chalk rests on the lowest part of the lias formation, which has a superficial breadth of only a few yards. It, however, expands again towards the north, and shows itself very completely developed on the coast of Yorkshire. Detached portions of this formation accompany the new red and Permian systems in Glamorganshire, and lie unconformably in the hollows amongst ele- vated ridges of carboniferous limestone. Through the whole of this range some general physical features, Lias formation in Yorkshire, North- amptonshire, and Somersetshire. LIAS RANGE YORKSHIRE AND LINCOLNSHIRE, 285 almost constant mineralogical qualities, and prevalent species of organic reliquiae, fix such a decided character upon the lias formation as to establish a good geological horizon for the guidance of the English observer. The country which it occupies is in general a broad vale at the foot of the escarpments of oolite, and terminating towards the red marl by a very connected range of uniform low hills. A considerable portion of the steep slope of the oolite escarpments is occupied by the lias; and in the Midland Counties, particularly, owing to the action of currents of water, detached portions of oolite crown the summits of many insulated masses of the upper lias shales. From the coldness and stiifness of the soil, much of the surface of the lias clays remains in pasture, for which it is well adapted ; and where the plough has in former times been employed, the land is thrown up into very high ridges for the sake of surface drainage. Water is scarce in this tract, and, because of the abundance of py- rites, often sulphureous or ferruginous, or impregnated with purga- tive muriates and sulphates. A general tendency to an argillaceous type belongs even to the limestones of the lias formation, and its clays more frequently exhibit a schistose structure than the other clays of the oolitic system. Layers and masses of jet are frequent in it, especially in the northern part of its course ; pyrites is one of its most abundant productions, especially in connection with ammonites and other shells, and sulphur in some parts is so prevalent as to furnish a valuable manufacture of alum. Many fruitless trials for coal along the line of the lias clays are upon record, to serve as a warning to those unacquainted with geology. Very remarkable organic exuviaa belong almost equally to every part of the English lias. Skeletons of saurian and chelonian reptiles, several species of scaly fishes, abundance of ammonites and belem- nites, plagiostomata, gryphaeae, &c., and considerable quantities of the wood of coniferous trees, enable the naturalist to form very reasonable views of the state of the ancient land and sea when this formation was in progress, and serve not only to identify it in all parts of Eng- land, but even over a large part of its extent in France and G-ermany. Nevertheless, there are important geographical peculiarities con- nected with the lias of England, which deserve a short analysis, the better to enable us to perceive the circumstances under which the ancient sedimentary deposits of the sea took place. IJa* in Yorkshire and Lincolnshire. The section of the lias, as it exists in Yorkshire and Lincolnshire, is peculiarly instructive and complete, and forms an excellent type with which to compare the detached portions of the formation in north Britain and the south of England. We shall take the groups in the ascending order of their antiquity. 286 MIDDLE MESOZOIC STKATA. Lias limestone. The calcareous beds included in this division are in the north of England very distinctly divided into two or more portions separated by a considerable thickness of clay. 1. The lower limestone, 10 to 20 feet thick, is not traced farther north than the Humber. It consists of compact blue or gray lime- stone, generally laminated and shelly, with partings of whitish clay or marl. It rests immediately upon the red marl and gypsum. 2. Clay, 50 to 100 feet, with layers of nodules, often septariate, full of pentacrinites, ammonites, plagiostomata, &c. 3. Upper lias or gryphite limestone, 12 to 20 feet, in rough, shelly, coarsely laminated beds, separated by partings of clay. The colour usually brown, but in wet pits and before exposure to the air inter- nally blue. But the most remarkable character of these beds is the astonishing abundance of gryphaBa incurva which they contain, or rather of which they almost wholly consist. In several parts of Lincolnshire the roads are mended with the most beautiful specimens of this fossil, and for miles together hardly any other shells can be collected from this part of the lias. Lower lias clay or shale, 300 to 500 feet thick, a dark homogene- ous clay or shale, with many layers of argillo-calcareous nodules, sel- dom containing shells, and in the lower part rough sandy beds. Coniferous wood, pentacrinites, plicatulse, gryphaea MacCullochii, pinna folium, and several ammonites, &c., occur in this stratum, but in it organic remains are not particularly abundant, and neither belemnites, terebratulse, nor saurians are so plentiful as in the beds above. No alum is made from this part of the lias shale. Marlstone series, 100 to 150 feet, consisting of highly arenaceous shales, and laminated sandy limestones of brown, greenish, or gray colour, succeeded above by several bands of nodular and stratified ironstone, of immense commercial value, the whole series particularly abundant in shells, besides producing beautiful asteroidea, annulosa, and fishes. Several species of terebratula3, cardium truncatum, deri- talium giganteum, &c., appear almost confined to these strata, which likewise contain gryphseaB, pectines, plagiostomata, terebratula?, and modiolae, not distinguishable from the ordinary fossils of the oolite. The marlstone beds are in fact the first term of the oolitic deposits, interpolated among the last terms of the lias, and, according as the clay above them is attenuated or developed, they may be ranked with the oolitic, or the Has formation. In the north of England, the former mode of arrangement must be adopted, but in the south, the latter has been often followed. The upper lias clay or shale, 50 to 200 feet in thickness, is the aluminous rock of Yorkshire, and passes by intermixture into the ironstone and marlstone series below, and by a gradual change into the analogous sandy beds of the oolites above. LIAS BANGE MIDLAND COUNTIES. 287 It contains a multitude of layers of argillo-calcareous nodules, mostly aggregated round ammonites and other organic bodies, and these are particularly remarkable and of larger size in the lower part of the shale, which also is much harder than the rest. A profusion of ammonites, belemnites, and nautili, accompanied by aviculae, ino- cerami, amphidesmata, &c., besides abundance of ichthyosauri, and plesiosauri, jet, and coniferous wood, enrich this interesting rock. Its thickness is variable, amounting to 200 feet on the coast, but diminished to 50 feet, or even less, in some of the southern Cleve- land hills, where also the usual smooth homogeneous texture of alu- minous shale is changed to a decidedly sandy composition. Uas in the Midland Counties. Proceeding to the south, we find the characters of the lias formation of Yorkshire maintained with con- siderable exactness through the counties of Nottingham, Lincoln, Leicester, and Rutland, into Oxfordshire. The section from Lincoln to Gainsborough shows clearly the upper lias clay, marlstone group, lower lias clay, gryphite limestone, and laminated limestone, all superimposed on gypseous red marl. In the vale of Belvoir, like- wise, through Rutland, and as far as the centre of Oxfordshire, we have the lower laminated limestone (1) surmounted by a thick clay, (2) in which lie gryphitic beds peculiarly shelly, which Mr. Cony- beare calls upper lias beds, and which correspond to the gryphitic beds of Lincolnshire. Still higher, are beds of green or brown marly sandstone, with terebratulsB, pectines, belemnites, and other shells, which are always ferruginous, and, in Rutland particularly, laminated and entirely similar to some of the marlstone beds of Yorkshire. Above these, in the same tracts, lie 100 or even more feet of clay, often forming insular hills between valleys of marlstone, and upon the whole the ferruginous sand of the inferior oolite. If any doubt has at any time been raised as to the real distinction in this country of upper lias clay, marlstone, lower lias clay, and double course of lias limestone, it has probably arisen from the ex- treme resemblance of the ferruginous marlstone of the Vale of Bel- voir, which divides the upper from the lower lias clay to the ferrugi- nous sandstone, which is the general floor of the oolitic rocks. In Rutland, however, the distinction is perfectly evident. Uas of the Cottswoid Through Oxfordshire and Gloucestershire the upper lias clay continually becomes thinner, and the marlstone beds in consequence approach nearer to the sand of the inferior oolite. It is no wonder, therefore, that they should be in these countries sometimes confounded. But the section of Painswick Hill, near Stroud, adduced by Conybeare,* sufficiently proves that the same principle of classification applies to the lias below the Cottswolds, as well as to the north-east moorlands of Yorkshire. In fact, by * Geology of England and Wales, p. 252. 288 MIDDLE MESOZOIC STKATA. merely taking the argillaceous beds which in this section separate the sands of the oolite from those of the marlstone, and calling them upper lias clay, the accordance with the Yorkshire section is per- fectly evident. This question was, indeed, effectually settled by Lonsdale's valuable investigation of the Cottswolds. That excellent observer clearly established the identity of the lias system of Glou- cestershire with that of Yorkshire, in general terms ; at the same time denning the amount of topographical difference which princi- pally affects the upper lias shale. In the southern parts of Gloucestershire, and in the vicinity of Bath, the upper lias clay becomes still more attenuated, and the marlstone beds more divided and mixed with the clay. Smith gave the name of marlstone to the laminated stony beds full of pectines and other shells which are found in the Somerset canal and other places, twenty feet or less below the sand of the inferior oolite, as may be noticed in his sections. In several places, these beds, from the deficiency of the clay above, are brought nearly into close contact with the sand of the inferior oolite. This distinction of marlstone beds can be carried farther south, to and beyond Ilminster. From Lonsdale's Essay in the Geological Transactions, we find the lias limestones to be thus arranged in the descending order : Feet. Blue lias. Consisting of beds of grayish argillaceous limestone, vary- ing in thickness from 2 to 1 8 inches, and separated by others of blue marl, which are generally less than 6 inches thick, but sometimes more than 2 feet ". 50 to 60 "White lias. Thin strata of yellowish white argillaceous limestone, with partings of pale brownish clay 10 Lower lias marl. Dark marl with calcareous concretions 20 Organic remains of ammonites, belemnites, pectens, oysters, &c., though most abundant in the blue Has, are more or less diffused through all the beds. Combining the section of the north of England with Lonsdale's and De la Beche's sections of the lias in the vicinity of Bath and Lyme, we shall have the following general table of the complete type of the English lias : 1. Upper lias clay, marl, or shale. " Upper lias shale." (Phillips.) 2. Marlstone beds. Q n/r-jji v i (Upper lias marl. (Lonsdale.) 3 Middle has clay jj^ ^ shale> fawytf f Gryphitic and laminated lias of north 4. Lias limestones and marls < of England. (Blue and white lias of Bath. 5. Lower lias marls and bone bed of Lyme Regis and Bath. These lower marls are thus described by De la Beche, at Culver- hole near Lyme, (section descending): LIAS RANGE COTTSWOLD. 289 Ft. In. Dark marl 3 Earthy dark gray limestone 10 Dark gray slaty marl 5 Irregular light gray limestone 10 Dark slaty marl 1 4 Compact gray limestone 10 Dark slaty marl, which rests on the light bluish-green beds belonging to the upper part of the new red sandstone system 7 Total 18 10 More detailed sections of the bone beds at Aust Passage and Wainlode, and Westbury Cliff, have the further advantage of disclos- ing the "bone bed" full of reptilian and ichthyan remains, and the limestone richly charged with insects. The interest of these situ- ations is augmented by marks of wave action on some of the beds.* The following is the section at Wainlode, as given by Brodie : Ft. In. Bluish clay 3 Hard blue limestone, (" bottom bed") with ostrea, modiola minima, and other shells 4 Yellow shale, with traces of fucoids 10 Gray and blue limestone "insect limestone" 5 Marly clay 5 3 Hard yellow nodular limestone, " cypris limestone," with small shells, like cyclas, a species of unio, plants. (Naiadaceae ?) Cypris, and very rarely scales of fish (analogue of the Gotham or landscape lias of Somersetshire) 8 Yellow clay 9 Black shale 3 Hard gray (sandy) stone with impressions of fucoids on the upper sur- face, with scales and teeth of fish, viz., gyrolepis, hybodus, acrodus, and saurichthys, which also occurs in the true ' ' bone bed " 1 Black slaty clay 1 6 "Pecten" bed hard pyritous sandy stone 4 Black shale 8 u Bone bed," here hard and pyritous, composed of bones, scales, and teeth of fishes ; connected with this is a white and yellow sandstone, full of casts of pullastra arenicola 3 Black shale 2 34 8 The shore of the sea, and the vicinity of land, are clearly indi- cated by these deposits, which apparently change their characters or vanish in the north of England. Insects have been found by the same observer in other and higher parts of the section of the lias ; as at Dumbleton, in the " fish beds " of upper lias, above the marl- * Strickland, Geol. Proceedings. Brodie, Mem. on Fossil Insects. De la Beche, Memoirs of Geol. Survey, vol. i. U 290 MIDDLE MESOZOIC STKATA. stone. Fruits have been found in the upper lias of Lincolnshire, (Morris.) ijias in North Britain. Murchison's Memoir s on the Oolitic Deposits of North Britain most clearly prove the existence of well-character- ized lias shales, much like those of the Yorkshire coast, in Pabba, Skye, and other of the Western Isles, and the organic remains which he collected there are of the usual English types. Lias occurs also on the north-east coast of Ireland, as at the Giant's Causeway, with ammonites and belemnites. The lias in South Wales is a singular extension of the formation among the dislocations of the older carboniferous system, nearly analogous to its appearance among the sandstones and slates of Scot- land. The valley of the Ely, in South Glamorganshire, exhibits several upfillings of lias, commencing about five miles west of Llan- daff, whence, with some interruptions, they accompany the Ely to its junction with the Channel near Penarth Point. It again appears in Barry Island, and continues to skirt the coast in a westerly direction nearly to the mouth of the Ogmore river, forming a range of bold cliffs, among which is the little harbour of Aberthaw, celebrated for the lime which it exports. (Conybeare, Geology of England.) JLisut in France and Germany. We may now turn Our attention to the general types of lias presented in the north and south-east of France, and in various parts of Germany. As hi England, so generally in these countries, the lias is depo- sited conformably to the saliferous system, but in Brittany and around the plateau of primary rocks in central France, especially about Autun, the oolitic system often touches the granitic series without any interposition of red sandstones. In the district which borders that plateau on the east, between Chalons and Autun, the oolitic rocks are considerably developed with lias at the bottom, and all based upon gypseous red marl ; but the lias clays are here almost wholly deficient, and the formation consists only of the gryphitic limestone, with its partings of clay. The abundance of gryphsea in- curva, and other characters of the stone, strongly remind the travel- ler of the analogous beds in Lincolnshire. The lias and oolites are so closely allied that Desnoyers, in his description of this tract, hesi- tates even to distinguish the former as a fourth stage of the calcare- ous or oolitic system. South of the Ardennes mountains by Luxemburg, Metz, and Nancy, the lias exhibits more developed characters. Immediately upon the Keuper marls rests a considerable bed of sandstone, white, yellow, or rarely brown, sometimes solid, and sometimes friable; gradually passing into the lias beds above. From its abundance under and around the fortress of Luxemburg, it receives in that country the name of gres de Luxemburg. LIAS BANGE SWITZERLAND. 291 The proper gryphitic lias limestones succeed and cap most of the plateaux of grit. The beds are bluish and compact, and alternate with gray friable marls. Above are gray marls and marly grits, which correspond to the lias clays and marlstone of England ; and these are followed by the ferruginous sandstones which form the general floor of the oolitic system. In Wurtemberg, and, perhaps, generally on the German side of the Rhine, the lias has more of the character of the English series both as to mineralogical composition and organic remains. In par- ticular, the saurian reliquiae, so abundant in the lias clays of England, are all found in those of Boll and other parts of Wurtemberg, and with some additional species have been described by M. Jager of Stuttgart. Fine specimens of saurian animals occur in many of the museums along the Rhine. But perhaps the most remarkable accordance between the series of Germany and that of England is ob- served at Banz, near Coburg, where the Maine crosses the northern extremity of the Franeonian range of oolites. Here Murchison has observed the following section : Sandstone cap of the lias 300 feet thick. Upper lias shale of Yorkshire 40 Marls and marlstones 150 Lower lias shale, with compact lias and ammonites Hawskerensis, near the top 300 Gryphite limestone Gritstone Keuper formation At this place the most astonishing profusion of saurians, fishes, Crustacea, ammonites, nautili, and belemnites, as well as pentacrini, gryphites, and other fossils, occur ; and many of them remarkably agree as to their place in the strata with the arrangement of the same species in the beds of the coast of Yorkshire. Switzerland. Lias shales occur below the Alpine or Jura limestone of Switzerland and Savoy, and occasionally, as at Meyringen, Bex, the Mont Joux, produce some of the characteristic ammonites and be- lemnites of the English lias. In the Valley of the Arve, in particular, the argillaceous beds of lias are immensely thick, and, owing to the igneous agency, once so powerfully excited beneath the Alps, have a schistose character strongly assimilating them to the primary slates. If the slates of the Valorsine belong to the same era, as their belem- nitic reliquia? indicate, the vegetable remains which they contain, being identical with those of the carboniferous epoch, would indicate that these regions enjoyed a particular immunity from the causes which, in all other instances yet examined, had wholly destroyed the plants which grew in the carboniferous epoch, and covered the earth 292 MIDDLE MESOZOIC STRATA. with cycadeae and other entirely new types of vegetable life*. The beds yielding belemnites and those containing plants seem to be in alternation. The whole series seems, at least in some localities, to dip under (or rather toward, for actual contact is rarely reported) the gneissic ridges of Mont Blanc, which also seem to dip under their sovereign, so as to make the whole structure "fan-shaped." This subject has provoked very many examinations and discussions. Sharpe, the latest observer, has detected the existence of several anticlinal and synclinal axes, both of " foliation" and stratification. The former structure (analogous to or identical with cleavage), being generally the most apparent, has, perhaps, most frequently caught the attention of travellers, and raised that impression, so general among the Alpine geologists, of the peculiar "fan-shaped" structure which has been found so embarrassing.* Lower Oolite Formation. The uninterrupted range of this formation through Dorset, Somer- set, Gloucestershire, Oxon, Northamptonshire, Rutland, and Lincoln, to the banks of the Humber, may be seen on the maps of Smith or Grreenough. Beyond the Humber it is concealed for a short dis- tance beneath the overlying chalk, but emerges again, and occupies a vast breadth in the eastern part of Yorkshire. In Sutherland, and in some of the Hebrides, and particularly in Skye, it has been traced by Murchison. It occupies, through all its course in England, an elevated range of hills with bold escarpments to the west or north-west, a gentle slope to the east or south-east, and deep valleys of denudation which often, by descending to the lias clays, furnish most complete infor- mation as to the relations of the two formations. The surface of the calcareous portions is dry and bare of trees, and wells sunk therein often reach a very considerable depth, while upon the alternating clays the soil is cold or wet, and, in general, much covered by woods. The fertility of the district is below the average of the secondary strata. The highest point of the range in the south of England is Cleeve Pipard Hill, near Cheltenham, 1,134 feet above the sea ; and in the north of England, Burton Head, near Ingleby in Yorkshire, 1,485 feet ; but in these cases about two-thirds of the height consists of the lias clays. The more ordinary altitudes of the oolitic range in England are 700, 800, and 900 feet, varying according to the westward extension of the hill, the thickness of the base of lias, and the pile of incum- bent strata. * GeoL Proceedings, 1855. LOWEE OOLITE FOBMATIOff. 293 Escarpments. Certainly this regular and continuous range of oolites, with so nearly uniform an elevation of escarpment, is one of the most characteristic features of English geology, and furnishes matter for profound reflection. For, like the parallel, equally continuous and regular, and but slightly lower range of chalk, its elevation seems not at all due to local disturbances, but rather appears to indicate a general intumescence of the land in the direction of these ranges. The low vales of lias, Oxford clay, and Kimmeridge clay, which in- tervene between the lower, middle, and superior oolite ranges, have undoubtedly been caused, at least in part, by the erosive action of water ; but to whatever extent we apply this principle in explaining the present inequality of the earth's surface, and whatever aid we receive from the established data of local elevation, these limited agencies always leave unexplained the general fact, viz., the regular altitude of continuous ranges of hills with uniformly declining planes, and no particular marks of convulsion, which overlook exten- sive undisturbed plains of older strata. The vicinity of Bath, where Smith began his important researches, furnishes the general type of the lower oolite formation ; and, with some modifications, the series of strata here presented, as detailed by Smith and Lonsdale, is found to be almost universally reconcilable with the phenomena of the other oolitic districts. The variations observed are principally caused by the interpolations of a larger pro- portion of arenaceous, argillaceous, and carbonaceous beds, so as in extreme cases to change the calcareous section of Bath into a coal field, with subordinate beds of limestone. Such is especially the case in the eastern moorlands of Yorkshire, at Brora in the Hebrides, and in the gorge of the Weser at Minden, as observed by Murchison. The table of classification given above will make known the order of succession of groups recognized in this formation, and we shall now proceed to point out their characters and notice their variations more exactly. inferior Oolite Group. The sand which is the base of the inferior oolite group in the vicinity of Bath possesses, in general, only a slight degree of cohesiveness, but in places passes into a friable sandstone. It is micaceous, of a yellow colour, and contains irregular courses of calcareous concretions called sand burrs. These nodules are often aggregated round ammonites and other organic bodies. The thickness of this bed sometimes amounts to 70 feet. The inferior oolite varies in thickness, in some places being 60 feet, in others considerably less. The rock, according to Lonsdale, admits of being characterized in three portions. The lower one, 6 feet, hard, of a brown colour, abounds in casts of trigonise, lima?, trochi, &c., and is seen in many sections reposing immediately on the sand. The coated mussels, as they are termed, are found in this bed, which, in 294 MIDDLE MESOZOIC STEATA. the quarries near Bath, yields an immense abundance of species. The middle division, 10 feet, is a rubbly stone ; principally consisting of crystallized carbonate of lime, through which the organization of astrsesB may be clearly traced. It is, therefore, a coral bed, and, as might be supposed, is of irregular occurrence. The upper portion of the rock, 40 to 50 feet at the utmost, con- tains the workable freestone or oolite of this rock. The upper part, in particular, cannot be distinguished in specimens from the great oolite above. The lower beds are more sandy, browner, and less oolitic. The Fuller's Earth Group. The Fuller's earth group, so named from the occurrence in it of limited beds of that substance, is a thick argillaceous deposit with a few layers of nodular limestone and in- durated marl, occurring on the hill sides of Bath, and distinctly sepa- rating the inferior from the great oolite. The following is Lons- dale's summary of these beds : Feet. 4. Blue and yellow clay with nodules of indurated marl 30 to 40 3. Bad Fuller's earth 3 to 5 2. Good Fuller's earth, brown or blue 2| to 3 1. Clay containing beds of bad Fuller's earth and layers of nodular limestone (Fuller's earth rock) and indurated marl 100 The Great Oolite Rock. The great oolite rock contains, besides the more perfectly oolitic parts, which hold few shells and furnish the best freestone, a great number of beds, in which the oolitic structure is less evident or even wanting, and which are more or less filled with remains of shells, corallines, &c. These coarser portions of the rock lie at the top and bottom, and enclose the purer oolite between them. The lower rags consist of several beds of coarse shelly limestones, 10 to 40 feet. The lowest bed of it which rests on the Fuller's earth group is fine grained and scarcely oolitic. The oolitic beds in the middle are very variable in thickness and quality. On Combe Down the thickness sometimes amounts to 30 feet. The stone when taken from the quarry is quite soft, and holds so much water as to be beaten to a pulp by the hammer. After being thoroughly dried, it will absorb more than one-seventh of its weight of water, but by long exposure it grows harder and less ab- sorbent. It will not stand the sea air, though in the neighbourhood of the quarries it is very durable. The upper rags, 20 to 55 feet, consist of alternating beds of coarse shelly limestones, tolerably fine oolite sand, tough, brown, argilla- ceous limestone. The shelly beds were used by the Romans in their buildings at Bath, and are thought to be very durable, but are diffi- cult to work. Some of these beds are full of millepores and other polyparia and species of echini, and a profusion of minute univalve LOWEE OOLITE TOEKSHIEE. 295 and bivalve shells. They often exhibit that peculiarity of internal lamination called false bedding, when the ingredients of the stone form layers inclined to the plane of stratification. The Forest Marble Group. The forest marble group admits of the following subdivisions in a descending order : 6. Clay with occasional laminae of grit 15 Feet. And at Norton St. Philip a layer of rubbly indurated marl abounds with fragments of a small oyster and terebratula. 5. Sand and nodules, or beds of calcareous gritstone 40 The sand is reddish-yellow or white, pure or mixed with clay, or lime. The gritstone, usually of a brown but sometimes of a blue colour, exists in spheroidal masses which have a laminated structure parallel to the stratification, and occasion- ally can be split into flags. The fracture often shows shining facets of interposed carbonate of lime. Organic remains are generally rare in these beds, some- times particularly abundant. 4. Clay with thin slabs of stone and laminae of grit 10 3. Coarse oolite, or shelly limestone (forest marble) full of fragments of wood and shells, especially ostreae and plagiostomata, bones, teeth, &c. The majority of the beds have a fissile structure, and can often be split into thin flags, or tiles, oblique to the plane of stratification. Thin partings of clay generally divide the beds. 2. Sand, or sandy clay and grit 10 1. Pale blue or gray clay, enclosing thin slabs of tough brownish limestone and laminae of calcareous sandstone or grit. Thick- ness variable 5 to 40 The Cornbrash. The cornbrash consists of numerous rubbly beds of coarse limestone, mixed with clay, altogether 10 to 15 feet thick. The beds or rather nodules are extremely irregular, and of different colours, but they are pretty uniformly composed of tough granular limestone, and abound with terebratula?, avicula echinata, isocardia, amphidesmata, &c. In tracing the lower oolite formation to the south from the Bath district, the inferior oolite is found to become more ferruginous (Sherborne), and with its subjacent sand to cap the lias as far as Bridport, but the great oolite soon "thins out," while the forest marble group thickens and becomes predominant. The cornbrash retains its usual characters and fossils. Yorkshire. In the district lying north of the Humber the lower oolitic system assumes entirely new characters, which will require se- parate consideration. The beds seen in the imperfect exhibition of these oolites near Cave, where they divide the lias from the Oxford clay, are the sand of the inferior oolite covered by shelly and oolitic beds, a continuation of the oolite of Lincolnshire, and above them a thin bed of pale blue clay. They are here much diminished in thick- ness, and, though burnt to lime, somewhat debased in purity. On 296 MIDDLE MESOZOIC STRATA. the banks of the Derwent, the lias is surmounted by the same simple series, with the addition of beds of calcareous flagstone above. Far- ther along the range, at Brandsby and Wiganthorpe, the series is expanded by the interposition of beds of sandstone and shale, with a thin band of coal between the sand which caps the Has and the shelly limestone which here represents the oolite of Lincolnshire. Above the limestone runs a band of pale blue clay ; and upon this rests a succession of beds of sand and sandstone, enclosing spheroidal con- cretions of calcareous sandstone with glistening facets, often blue in the centre and full of shells, some of which resemble those of Stones- field. Beds of sandstone, shale, and carbonaceous matter are also interpolated above this slaty rock. The oolite here is hardly de- serving of that name from its lithological character ; for though this appearance sometimes presents itself, the greater part of the stone is a coarse, granular, shelly limestone, with embedded shells, &c. It is, in fact, the oolite of Cave still more degenerated. The series of sandstones and shales with coal which here overlies the sandstone cap of the lias, has been supposed analogous in position to the Fuller's earth group of Bath (the similar series which overlies the limestone beds corresponds to the interval between great oolite and cornbrash), and as we proceed northwards both series increase immensely in thickness, so that the lower one reaches 500 feet, and the upper one 200 ; and as, from local circumstances, the coal, though never more than 16 inches thick, is worth working, these moorlands assume the appearance of a true coal field, with subordinate beds of very coarse shelly limestone. It requires, indeed, very close observation to trace the thin limestone beds across these vast moors, and amidst such a number of sandstone beds. They are best studied on the coast, and in the fronts of the bold hills over Thirsk and the vales of Mowbray and Cleveland. The coast section admits of the following summary : Feet. e Shelly cornbrash limestone of Gristhorp and Scarborough 5 to 10 d Sandstones, shales, ironstones, and coal, of Gristhorp, Scarborough, and Scalby, enclosing some calcareous shelly bands 200 c Shelly oolite of Cloughton and White Nab with clays 30 to 60 & Sandstones, shales, ironstones, and workable coal, of the Peak, Stainton Dale, Haiburn Wylie 500 a Irony sandstone and subcalcareous beds, with bands of shells and plants 10 to 60 The irony sandstone (a) upon the lias is a variable rock, often coarse and fragmentary, sometimes with the characters of ordi- nary sandstone, but generally subcalcareous, ochraceous, and full of shells and casts. At Blue Wick, near Robin Hood's Bay, it presents a double band of fossil-bearing beds, the lower ones gra- dually passing to the subjacent lias. The limestone (c) appears LOWEE OOLITE YOEKSHIEE. 297 with different aspects at different points. Under Gristhorp cliffs it recalls pretty exactly the oolite of Cave; but at Scarborough, Cloughton, Hawsker, Sneaton, &c., it is a very different rock, coarse, fragmentary, and mixed with veins of earthy, ferruginous, and argillaceous oolite, so as to be scarcely fit to be burned to lime. In the Stainton Dale cliffs it is a double band ; at White Nab it is covered by variable sandstones, in which glistening facets, like those in the stone of Brandsby and Wittering, occur. Only one seam of coal is worked in the district, and that lies about 100 feet or more beneath the limestone. The cornbrash (e) appears on the coast, also, in a debased but recognizable form. The fossil plants which accompany the coal seams and sandstones (b, d) may also be detected in the limestones and calcareous slates both on the coast and at Brandsby ; and it is worthy of particular attention, that both at Collywestori and at Stonesfield several of such plants occur in the slate, as brachyphylla, ferns, and cycadites. No marine exuviaB have yet been found in these coal grits or shales, but some bivalves resembling anodon, and a crustacean like cypris, which per- haps were swept down with the ferns, equiseta and eycadea?, are found at Gristhorp. In several places a particular part of the section of lower carboniferous sandstones (Ji) exhibits the remarkable phe- nomenon of equiseta standing irregularly erect over considerable areas in a bed of sandstone which rests upon shale.* This is, therefore, truly a coal field of the oolitic era, produced by the interposition of vast quantities of sedimentary deposits brought down by floods from the land, between the more exclusively marine strata of the ordinary oolitic type. We may believe this to be a case of a littoral deposit of oolite, and should naturally derive from that supposition, the debasement of quality and attenuation of thick- ness of the shelly limestone, in proportion as the spoils of the land brought down into the sea were more abundant. Whatever the causes were which produced these effects, they were not entirely local. The Yorkshire oolitic district is indeed the only tract yet investigated in England which exhibits these effects in a striking manner ; but attentive consideration of the phenomena presented by the rag beds of oolite and coarse shelly beds of forest marble near Bath, and still more the wavy surface and vegetable fossils of some kinds of the sandstone slate of Stonesfield, and Collyweston, will lead to the conclusion that these portions of the oolitic formation were deposited within the influence of the littoral agitation of the sea, or in lagoons enjoying greater tranquillity. Morris has lately proved that the series of argillaceous beds with plants and cyrenaB, which lie over the great oolite of Lincolnshire, are coeval with the plant beds (d) of Gristhorp, and like them * Geology of Yorkshire, vol. L, 1829. 298 MIDDLE MESOZOIC STBATA. covered by the cornbrash (e)* This littoral or lagoon deposit is traceable in Oxfordshire, above the oolite which covers the Stonesfield slate. The extensive additions of terrestrial plants and sediment are con- fined to the intervals between the sand which is the base, and the cornbrash which is the cap of the lower oolite formation. The bands of ironstone on the Yorkshire coast have, for many years, yielded small supplies, chiefly gathered from the shore, to the furnaces of Northumberland. The lias bands above the ironstone, and those immediately above the oolite of White Nab, were found the most valuable. Within the last few years the lias band, often sixteen feet thick, and of good quality, has been worked with great advantage at Eston and other points in Cleveland, as well as at Gromont Bridge, in Eskdale. The area under which this bed may be worked measures some hundreds of square miles, with an average produce of 20,000 to 50,000 tons per acre. It dies out southwards, and vanishes about Thirsk ; but there other ironstones acquire value in the oolitic series above. The section of the strata of the Bath or lower oolite series in the Thirsk district presents the following general type : (Above are the Coralline oolite, calcareous grit, Oxford clay, and Kelloways rock.) e Cornbrash, barely traceable. d Sandstones, shales, ironstones, and carbonaceous bands, 250 feet, one layer of iron- stone nodules very rich, no coal bed visible. Plants in some of the layers ; fine white arenaceous freestone. cf Calcareous oolitic and shaly beds, with layers of shells, and irony bands of different degrees of richness, not here workable, about 30 feet in all. The calcareous parts are often found to be minutely oolitic, some layers are penetrated by a calcareous crystallization, giving the "glance" aspect. b Sandstones, shales, ironstones, one 3 feet bed, and several bands of nodules, all good in quality, and mostly workable, bands of cement nodules, one bed of coal, occasionally worked. 320 feet. a Calcareous shelly partly oolitic ironstone, 7 to 12 feet thick, 20,000 tons per acre, of good quality, over it in some places shale, with a band of ironstone nodules. This is the cap of the upper lias. About 100 feet lower is a poor representative of the Eston band of ironstone, in the lias. Scotland Murchison's examination of Brora and other points in Sutherland, and of the western coast of Scotland, has proved the ex- tension of the carboniferous system of Yorkshire oolites into these northern regions, and it is interesting to observe that there, as well as in Yorkshire, the interpolations occupy the same limited space in the section. * Geol. Proceedings, 1853. f This group somewhat resembles cornbrash, and contains ostrea marshii, but the facts gathered in a recent survey, 1854, being carefully considered, I have no doubt of its representing the rocks of White Nab. LOWER OOLITE MIDLAND COUNTIES. 299 The following short summary of the beds in these counties will prove this point : Section of Brora. Lower oolite formation consisting of. ' Shelly limestones representing cornbrash and forest marble. Alternations of sandstones, shales, and ironstones with plants. Ferruginous limestones, blue in the interior, with frag- ments of carbonized wood and abundance of shells. Sandstones and shales of great thickness in frequent alter- nations with plants, having in the upper part two beds of coal, of which the upper one is 3 ft. 8 in. thick, the lower one, not worked, 1 ft. 4 in. Lias formation with fossils of the Yorkshire lias. North-East Coast, Isle of Skye. Sandstone series. Shelly limestone. Sandstones and shales of great thickness, with obscure impressions of plants and abundance of carbonaceous matter. Calciferous sandstone beds, with small nodules of indurated limestone grit, with fossils and thin layers of shale with belemnites. Blue shale (upper lias shale of the Yorkshire coast) with small blue calcareous concre- tions, belemnites, &c. Sandstone with concretionary nodules and fossils of the marlstone series. Lias shale. Geological Transactions, Neio Series. The same geologist has found a considerable analogy to these phenomena in the section presented by the gorge of the Weser, where that river escapes through the Porta Westphalica into the plains of Northern Germany. How unlike to the general type of the oolitic formation of the German and Swiss Jura. Midland Counties. Having thus produced the two most contrasted types yet discovered of the oolite formation, and by their comparison put a severe check upon the doctrine of universal formation (if such was ever entertained) among the secondary strata, it will be useful to state a few more sections of this formation in the intermediate parts of its range in England, especially of the parts which are most subject to variation. The curious fact of the continuity of the cornbrash above, and of the lower oolite sand below, from one end of England to the other, by furnishing everywhere exact limits to the formation, very much abridges the inquiry into these variations, and diminishes the chances of error. In the long range from the coast of Dorsetshire to the coast of Whitby, the character of the lower sand varies, yet not so much as is common to sandstones, the principal difference consisting in the colour which is occasioned by the degree of oxidation of the iron. Through Oxfordshire, Rutland, Lincoln, and the southern 300 MIDDLE MESOZOIC STEATA. part of Yorkshire, it is a very dark brown ferruginous rock, whence it is often called "gingerbread stone," frequently enclosing shelly concretions (Banbury), occasionally enveloping beds of limestone, and sometimes (Northampton, Kockingham) interlaminated by white beds of oolite. The quantity of oxide of iron is sometimes so con- siderable as to divide the mass of the rock into a multitude of ochra- ceous cells or "iron boxes." In some places, especially in Lincoln- shire, it consists of an alternating series of white and brown sand. Ironstone (sometimes other iron ore) occurs in Northamptonshire and Oxfordshire, not only in the lias but also in the oolitic series as in Yorkshire. With respect to the cornbrash it is sufficient to say, that though so unimportant a rock in other respects, it is probably more conti- nuous, and more uniform in its character from Dorsetshire to the Humber, as may be seen in Smith's maps, than any other member of the oolitic formation except the sand of the inferior oolite. Lincolnshire. Lincolnshire presents the following section of this formation (observations made in 1821) : Cornbrash full of its usual fossils. relay thin, j Thin shelly beds in one locality, somewhat resembling the blue beds of Farley near dl Bath> I A considerable thickness of clay forest marble system of Wiltshire. [_ Sandy laminated stone, in a few localities south of Lincoln. c Thick, apparently undivided, oolite rock, very productive of organic remains, with polypiferous beds on the top. In the upper parts of this rock, false bedding is frequent, coarse shelly rags abound, good oolite is dug at Ancaster. This is undoubtedly the same rock as that of Cave in Yorkshire, and it is continuous with the same general character as far as Grantham, between which place and Stamford there appears to be some change. a Inferior oolite sand. On the line from Wandsford, through Weldon to Buckingham (1821) : Cornbrash very distinct. Clay of some thickness, nothing else observed. Weldon oolite or rag, the same as the Barnack rag. Interval, presumed to be clay, under some breadth of Rockingham forest. Brown sand of Rockingham Hill, with interlaminated white limestones. It might appear from these statements that the slates of Witter- ing and Collyweston are near the northern end of these deposits ; they are unknown at present in a distinct form north of the Welland, LOWEE OOLITE STOKE SFIELD. 301 The following interesting table by Morris* exhibits the varying thickness of the clays, in the group between the corribrash and great oolite of the southern part of Lancashire : Essendine. Aunby. Dane's Little Creeton. Counthorpe. Hill. Bytham. Oyster bed and marly rock 11 16 8\ 1fi (5 Clays ". 9 20 6 10/ \4 Stem-bed 2i 3 2 l 5 Clays 4 7 15 10 10 14 Iron band present 1111 Oolitic rock... 10 8 13 The main features of this table are recognized in all the railway cuttings north and south-west of Oxford (1854). Collyweston slates The slate of Collyweston is associated with beds of oolite and compact limestone, and presented to Murchison and the author (1831) the following detailed section : Local Names. Ft. In. Description. Rubble 4 Imperfectly bedded oolite. Cale 4 Irregular and broken beds of oolite. ( Fine yellow sand indurated at top and at bottom into Bedding sand 1 3J co ie ti onary and slaty layers. -rj _ /Brown hard oolite graduating upwards to the sandy )aa 4 u \ layers above. Thin beds, not burnt to lime. ("Hard, compact, not oolitic, containing brachyphyllum, Limestone 1 6 { ferns, and trigonellites. Betch 1 3 Irregular sandstone. ( Masses irregularly spheroidal flattened, very fissile, hi Slate 2 to 4 < general calcareous grit not at all oolitic, but shelly, ( with littoral and terrestrial plants. Fine sand Of a yellowish colour. The slate is quarried only in winter, for if dried by the summer sun and wind, it hardens and will not split. The holes are blocked up in spring, and the quarrymen only employed in preparation of slate. It is, in general, very equally laminated. The splitting is caused by organic exuvise. Stonesfield Slates. The Stonesfield slates near Oxford have been almost universally esteemed to be of nearly the same age as these Collyweston rocks. Both are below the mass of great oolite (usually separated from it by clay), and both are above the inferior oolite. The Stonesfield slate is often assumed to be above the Fuller's earth, the Collyweston slate below it. At Stonesfield two beds of concretionary masses, capable of being easily (with the assistance of frost) split into slate parallel to the stratification, compose with sand and friable sandstones a group five or six feet thick, under fifty feet of alternations of laminated * Geol. Proceedings, 1853, p. 338. 302 MIDDLE MESOZOIC STEATA. shelly oolite and thin blue clay. The following is Dr. Fitton's ac- count of the section (Zool. Journal, vol. iii.) : Rubbly limestone. ~] Clay with terebratulites. I Limestone. 1 32 feet Blue clay. Oolite. Blue clay. " Rag," consisting of shelly oolite, with casts of bivalves and univalves. r " Soft stuff," 6 in. yellowish sandy clay with thin courses of fibrous transparent gypsum. " Upper Head," 1 ft. 3 in. to 1 ft. 6 in. sand enveloping a course of spheroidal laminated calcareous gritstones which produce the slate. These are called " Pot-lids" from their figure, and receive The slate beds consisting of The slate beds with the other slaty bed the name of Pendle, as characteristic of the workable stone. The stone is partially oolitic and shelly, sometimes full of small fragmentary masses. " Manure or Race," 1 ft. slaty friable grit rock. Lower Head, 1 ft. 6 in. to 2 ft. sand and grit, including a course of spheroidal concretions of slate like that described above. consisting of j Bottom stuff, 1 ft. sandy and calcareous grit with admixture of (__ oolitic grains. The floor of the slate beds is rag like the oolite above. Most of the Stonesfield fossils, and in particular the jaws of mam- malia, have been extracted from one or other of the courses of slate. We may now return to the Bath series of oolites, and accompany Lonsdale in his survey of their extension to the northwards. Lower Oolites of Gloucestershire. The inferior oolite in the south of Gloucestershire consists of nearly equal divisions of soft oolite and slightly calcareous sand ; but in the northern division of the county the latter, for the greatest part, is replaced by a yellow sandy lime- stone. The freestone beds, which are not to be lithologically distin- guished from those of the great oolite, gradually increase in number and thickness from the neighbourhood of Bath to the Cotteswold, east of Cheltenham, where they constitute the whole of the escarp- ment. Murchison* gives to this rock at Leck-hampton, above Chel- tenham, a thickness of 150 feet. At Lincover the beds have the under-mentioned local names : Ft. In. f Trigonia grit, named from the prevalent shells 4 Upper part. < Argillaceous parting, Trigonia speciosa 4 ( Gryphite grit contains Gry phaea, Lima, Terebratulae 10 Oolitic marlstone (Terebratula fimbria) 8 Freestone 30 Lower ragstoneor roestone (shelly) 6 Pisolite or pea grit (shelly) 4 This vertical importance is retained through the north of the country examined ; but to the eastward of the valley, ranging from * Geology of Cheltenham. LOWEB OOLITE GLOTJCESTEESHIEE. 303 Stow on the Wold to Barrington, near Burford, a change takes place both in the structure and thickness of the formation. The freestone beds are there replaced by strata of nodular coarse oolite, containing numerous impressions of clypeus sinuatus, the sandy por- tion consists of only a thin bed, and the thickness of the whole of the inferior oolite group is diminished from 150 to about 50 feet. The Fuller's earth loses its importance in proceeding northward, yet it was traced as a parting between the great oolite and the inferior oolite, as far as a line passing from the neighbourhood of Winchcomb to Burford, but to the north-east of this line it thins out. Great oolite. The threefold arrangement of upper rags, fine free- stone, and lower rags, into which this rock is naturally divided near Bath, does not prevail uniformly in our progress northward. The upper rags, consisting of soft freestone and hard shelly oolite, were traced to Cirencester ; but to the north-east of that town they are replaced by a rubbly, white, argillaceous limestone. The beds of the middle division become chiefly a hard oolitic limestone. At Wotton under Edge the lower rags are replaced by beds of fissile, calcareous sandstone, which run through the whole of Gloucester- shire to the neighbourhood of Burford. They are extensively worked as a tile stone, possess the lithological character of the Stonesfield slate, have their fissile property in the same way developed by ex- posure to atmospheric agency ; contain trigonia impressa, the charac- teristic fossil of Stonesfield ; and on comparing the strata of Burford with those which rest at Stonesfield on the slaty beds, it was found that an almost perfect identity of character and order of position prevailed at the two localities. The Windrush quarries near Burford give the following section for comparison with that of Stonesfield previously detailed : Top. Rubbly limestone 1 Foot. Brownish marlstone 6 Rubbly limestone 4 Pale sandy marl 3 Rubbly limestone Light-coloured clay .... Rag and freestome 15 Sandy laminated grit Lonsdale has thus corrected the almost universal error of English geologists in classing Stonesfield slate with the forest marble, and has assigned its true place at the base of the great oolite ; a most important alteration in every point of view. The forest marble was found to possess the same characters as near Bath, consisting of a thick stratum of laminated shelly oolite, interposed between beds of sandy clay, containing laminae of grit ; and to have, from Bath to near Fairford, for its uppermost stratum, a deposit of loose sand, containing large masses of calcareous grit. 304 MIDDLE MESOZOIC STRATA. It is hardly to be doubted that the slate of Collyweston is nearly coeval with that of Stonesfield ; the thick oolites of Lincolnshire comprise characters both of the great and inferior oolite of Bath. It is now ascertained that there are calcareous slaty beds above and below the great oolite ; or in other words, in two or perhaps three points of the series between the cornbrash and the inferior oolite ; it is known that both the great oolite and inferior oolite are subject to great variation of lithological character and thickness, and that the Fuller's earth which distinguishes these rocks at Bath is extinct, or nearly so, north of Burford. The littoral conditions indicated by these slaty beds with their included plants and insects, are now traced very far from Brora, Skye, and Yorkshire, into the midland and southern counties, and both in the northern and midland localities traces of fresh water action occur in the carbonaceous clays which lie in the same parts of the series. Perhaps by further search in them we may yet hope to add a fourth mammalian genus to those now recognized as the oldest insectivora in the British strata. Middle Oolite Formation. General Description. Very strong analogies accompany all the leading divisions of the oolitic system, and mark them as the pro- ducts of a succession of similar causes. As the oolites of Bath lie enclosed between strata of calcareous sand, so those of the middle division are embedded between strata of calcareous sand and sand- stone, and the association of the upper oolite with green sands at Swindon and Thame, is probably of the same intimate description. The organic fossils of all the divisions have a striking general re- semblance, and the composition of the rocks is liable to similar variations. The physical features impressed on the geography of the country which they traverse are also very similar. As the consolidated strata of the lower oolite formation form a high escarpment, which over- looks the plains of argillaceous lias ; so the limestones and sandstones of this middle group rest on a bold edge, above the vales of Oxford clay, and the upper oolite rocks in the few places where they occur domineer in the same manner over the vales of Kimmeridge clay. It might have been attended with some convenience to have con- sidered these thick clays in formations apart from the rocks, as the lias has been separated from the lower oolite, but they are from various causes so connected with them that it would have injured the practical utility of the classification. The general characters of the surface of the middle oolite forma- tion, are a moist valley of Oxford clay below a dry range of hills, MIDDLE OOLITE FORMATION. 305 furnishing copious springs from the calcareous grits and oolite. Dry valleys, deep wells, narrow dells, washed by the rapid streams, occur, especially in the districts of greatest altitude, and one un- acquainted with the series of formations might recognize in the general aspect of this, the description usually given of the lower oolite range. Outliers of the oolites and sandstones occasionally cover insulated hills of the subjacent clay, and prove the denudating power of ancient floods. The altitude of this range of oolite nowhere equals that of the lower oolite in the same region. Thus while in Yorkshire the older rocks rise in Burton Head to 1,485 feet above the sea, the later deposits reach on Black Hambleton 1,240 feet. In Oxfordshire and Gloucestershire 800 or 900 feet is the height of the lower oolite, but 400 or 500 feet that of the middle oolite. Range and Extent. This formation is upon the whole less conti- nuous than the one described before, yet the discontinuity is not of the whole mass, but chiefly of the group of oolites and sandstones. These have a considerable development in Dorsetshire ; first on the coast at Weymouth, and secondly, from near Sturminster to beyond Wincanton, where they produce oolitic freestone. Hence to Long- leat Park they are unknown. From Longleat their range is unbro- ken by Westbury, Calne, Wootton Basset, Highworth, Farringdon, and Abingdon, to the banks of the Thames below Oxford. They can be traced under Shotover, and towards Brill, a few miles, but their farther course is unknown, till we arrive at the Fens, where a single point of coral rag peers up between Cambridge and Ely. From this place they are again unknown till we cross the Humber, and see the oolite and calcareous grit under the Wolds of Yorkshire near Acklam. At this point emerging from beneath the chalk, they encircle the vale of Pickering by Malton, Helmsley, Pickering and Scarborough, increase greatly in importance, and assume more com- pletely than in any other part of England, excepting perhaps Wey- mouth, the full characters of their formation. But while the oolitic group is thus dismembered into four widely detached regions, the Oxford clay beneath is as remarkably connected from the north side of the Dorsetshire downs, by Wincanton, Melksham, the Yale of the Isis, Ottmoor, the Yale of Bedford, Huntingdon, the western border of the Fens, and the vale between the Cliff and Wold ranges of Lin- colnshire to the banks of the Humber. Beyond the unconformity of the chalk wolds, which here conceals all the oolites, its course is narrow, but undivided, beneath the slope of the calcareous grit round the Yale of Pickering to Scarborough. We shall now offer a few details of the internal structure and variations of these rocks. The clay below the Kelloway rock has been very little noticed, and is indeed not very important. It occasionally contains phola- x 306 MIDDLE MESOZOIC STRATA. domyae and shells near Bath, and more frequently abundance of selenite, and on the coast of Yorkshire has yielded some curious re- mains of Crustacea. As for the greater part of the range of the Oxford clay the Kelloway rock is unknown, this clay can seldom be distinguished. In Yorkshire it seldom exceeds a few yards, and generally is less than three feet in thickness. Kelloway Rock. The Kelloway rock, so named by Smith from Kelloway Bridge in Wiltshire, which is one of the few places where it occurs in the south of England, is in that county more re- markable for the beauty, peculiarity, and abundance of ammonites, gryphseae, and other organic remains which it produces, than for either its thickness or continuity. It is there a calcareous sandstone, appearing, when devoid of organic remains, very similar to those which accompany the coralline oolite, externally brown, internally gray or blue, of a rubbly nodular structure, altogether less than twelve feet thick. From Wiltshire to Northamptonshire no men- tion is made of this rock, but it was found with its usual fossils at Boziate Hill, near Wellingborough, by the writer of this volume, in company with Mr. Smith, in 1820. In 1821, the same observers established the occurrence of the Kelloway rock at Hackness and Scarborough on the sea-coast of Yorkshire. It is coextensive in that county with the range of the Oxford clay, from under which it rises into an escarpment. It ar- rives sometimes at a thickness of sixty feet, and is then locally dis- tinguishable into several portions. It is, however, altogether a mass of sand and calcareous sandstone, with or without organic remains ; the upper beds very thick, indurated by admixture of oxide of iron, and multitudes of gryphsese, belemnites, ammonites, and aviculae, and other fossils. Not unfrequently in the vicinity of the shells it becomes sufficiently calcareous to assume the character of a sandy oolite, sometimes ferruginous like that of Dundry. The sandy parts of the mass are often variously stained brown, reddish, yellow, or remain perfectly white, in layers or irregular stripes, and traversed by dissepiments of oxide of iron. In a very few places it is useful as a building stone. There is perhaps no more curious fact on record than the occur- rence of this apparently indefinite rock, with almost identical characters, after so great an interruption of continuity. Oxford Clay. The Oxford clay (clunch clay of Smith) appears, in the whole of its range south of the Humber, a pale blue clay, turn- ing yellow on the surface, with large sparry septaria, and some layers of chocolate-coloured shale (Tytherton), with ammonites and other fossils. In Yorkshire, it is less tough, and more generally arenaceous, gradually changing in quality to the Kelloway rock below, and the calcareous grit above. Most of the organic remains which it yields MIDDLE OOLITE COBALLIKE GEOUP. 307 belong to the lower part of the stratum, and are in general identical with, or very similar to, those of the Kelloway rock. Taken in general terms, the suite of fossils at Weymouth belonging to the Oxford clay is considerably allied to that of the Kelloway rock and Oxford clay of Yorkshire, but further comparison of the species of ammonites is yet needed. In the Museum at Strasburg fossils of the Kelloway rock, as well as of the Oxford clay, are recognized. It is painful to observe the dreadful waste of money in ill-advised trials for coal along the line of the Oxford clay. The least fragment of jet or morsel of bituminous shale, especially if accompanied by " blue metal," is enough to make a credulous proprietor listen to an ignorant collier, and throw away the value of his solid land in sinking for the imaginary treasures beneath it. Coralline Oolite Group. Lower Calc Grit, Wilt*, &c. The lower calcareous grit should be carefully distinguished from the iron sand, with which Smith has occasionally confounded it, nor is the distinction difficult, for, independent of its geological position, the calcareous grit is not particularly ochraceous, except in a single bed or so, as at Hackness and Scarborough, and never assumes that dark ferruginous aspect so remarkable in the other rock. In Wilt- shire, where it was first observed, it appears as a thick stratum of sand, enclosing irregular beds of sandstone, or of calcareous grit, which assumes the aspect of coarse limestone. These sandstones are brown externally, but gray or blue within. Irregular layers of clay occur in places, and friable beds of decomposed shells. The prevailing colour of the sand is yellow, but sometimes it is ash- coloured. At Studley, near Oxford, Dr. Bucklarid detected a pecu- liar bed of clouded gray colour, and very tough and dense texture, a sort of argillaceous chert, rich in pinna3, ammonites, and othei organic remains. It probably belongs to the lower part of the rock. The calcareous grit of Heddington, also rich in organic remains, ammonites, belemnites, plagiostomata, pectines, &c., is a very coarse rock, with an abundant admixture of quartz pebbles, chiefly of small size, and fragments of shells. It forms irregular beds and concre- tions in beds of quartzose sand, mixed with calcareous matter. Professor Sedgwick's description of the calcareous grit of Wey- mouth makes us acquainted with a more complete series than that of Wiltshire and Oxfordshire. The following statement of beds there is in the descending order : e Yellow sand like &, with beds of calcareous grit in the upper part. Beds of oolite succeed. d Blue argillaceous beds, alternating with hard compact beds with an even fracture. c Strong ferruginous jointed beds of calcareous grit. b Thin beds of yellow sand and sandstone. a The lowest beds upon the Oxford clay are black, and meagre to the touch, filled with irregular branching stems like alcyonia. 308 MIDDLE MESOZOIC STEATA. Lowr Caic Grit, Yorkshire, &c. The section of the lower calcareous grit on the Yorkshire coast between Filey and Scarborough has a striking resemblance to that of Wey mouth. Immediately on the Oxford clay rests a series of gray marly sandstones, 70 feet thick, gradually becoming more yellow and more consolidated upwards, till they assume the harshness which belongs to stones usually called cherty. This cherty bed appears to correspond with that mentioned before at Studley. It continues across the moors to Hambleton. Above these runs a band of yellow sand, 9 feet thick, enclosing large spheroidal highly indurated calcareous balls. This band is traceable through the interior, where it forms rabbit-warrens, as far as White- stone Cliff, and there the balls are of immense size. When they fall out, the rock looks cavernous. The upper part of the rock consists of strong beds of calcareous sandstone, very remarkably covered on the surface, and also penetrated by branching cylindrical bodies, which continually remind us of sponges or fucoids. The upper beds of this series are of a redder colour, and more calcareous than the others, remarkably full of shells, and in some places alternate with two or three beds of oolitic limestone also shelly. In the interior of the moors, they are often used for wallstone. It is not always quite easy to draw the line between them and the oolite above, especially when the latter is unusually shelly, and no coral bed intervenes. According to Lonsdale, there is in Wiltshire a pale blue clay, 10 feet thick, interposed between the lower calcareous grit and the coralline oolite. The coralline oolite, or coral rag group, as described by Smith, Conybeare, and Lonsdale, near Oxford, Wootton Basset, and Bath, seems not so complete a series as that described by Professor Sedg- wick at Weymouth, and by other authors in Yorkshire. Weymouth. The thickness of the whole group is greater in York- shire than elsewhere, but nowhere in that country exceeds 80 feet. The section at Weymouth gives above the calcareous grit the four following groups : Thick limestone series, at the bottom of which lie masses of coral rag, containing thecosmilia annulata, astraeae, &c. with innumerable fragments of trigonia cla- vellata. In the higher portion are many meagre sandy beds, nearly resembling the lower calcareous grit, but more calcareous, and with a finer suite of organic remains. h Beds of impure sandy oolite, containing besides other fossils, a few specimens of ostrea deltoidea. g Thin beds of oolitic marl, containing innumerable specimens of the small clypeus clunicularis. casts of melanise, &c. f Many beds of pure oolite with beds of argillaceous partings, alternating with other shelly oolitic beds, somewhat resembling forest marble. In some of these beds the oolitic particles are associated with a variety of marl, and are incoherent. Coralline Oolite, Wiltshire. Lonsdale describes the Wiltshire coral MIDDLE OOLITE YOBKSHIEE. 309 rag in three divisions, which do not succeed one another in any cer- tain order, but rather intermix with and replace one another. One of them, from which the formation takes its name, is an irregular mass of nodules mostly crystallized, but sometimes earthy, and con- nected together by pale bluish clay. These nodules consist of little else but corals of the genera isastraea, thecosmilia, and comoseris, especially the former, which sometimes separately compose the whole mass. The lower part of this bed sometimes affords a dark blue crystalline limestone. Another form of the rock is found in the oolite of Calne, which consists of alternations of hard shelly oolite used for flags, and soft, perishable, scarcely oolitic, limestone, workable by sawing parallel to the beds. This form of the rock passes into the third or rubbly oolite, which is the most abundant variety in Wiltshire. This is a nodular rock with very indistinct stratification and much irregularity of texture, occasionally with ova three-tenths of an inch in diameter, consti- tuting what is called pisolite. In the deep pit through Kimmeridge clay on the line of the Wilts and Berks Canal, this rock was very thin, scarcely oolitic, but chiefly a cellular mass of caryophyllise and astraase, and a similar character prevails in some quarries in the neighbourhood of Wootton Basset. Below it the lower calcareous grit was in the state of loose sand. Oxfordshire. Conybeare divides the coralline oolite near Oxford into two parts, of which the upper is a calcareous freestone of close texture, full of comminuted shells, and irregularly oolitic or pisolitic. The beds are very thick, and the stone has been much used in build- ings at Oxford, but is not found to be durable. The lower part is the true coral rag, consisting of two or three courses of nodular rubbly rock, very crystalline in aspect, and composed of masses of isastrsesB and thecosmiliae, with admixture of echinital and shelly fragments. Yorkshire. In Yorkshire the lower beds of the coralline oolite are in general exceedingly shelly, and full of clypeus dimidiatus, clunicularis, &c., and on the north side of the Vale of Pickering, at Hackness, Ebberston, &c., are marked by an irregular bed of coral (isastraese) and sponges. The middle part of the rock is regularly bedded with thin partings of clay and very large vertical joints. The different beds vary much in the same quarry, from a soft, loose, whitish oolite to a solid rock with blue centres and large pisolitic spherules. At Malton it is more uniformly oolitic, and very full of chemnitzise, trigonise, plagiostomata, &c., and organic remains of all kinds. Near the upper part in the Ay ton quarries is a bed of the- cosmiliae and echini ; and the rock is crowned at Sinnington, Helms- ley, &c., by a bed filled to excess with turritellae and chemnitzise. 310 MIDDLE MESOZOIC STKATA. Chemnitzia striata and turritellse occur near the top of the rock about Brompton and Hackness, but at Malton they lie indiscrimi- nately. Ammonites chiefly belong to the lower beds. About Kirk- dale and Helmsley layers of obscurely denned nodules of bluish - gray chert, having the texture of sponges, lie in the lower part of the rock, and remind us of the siliceous sponges of the Portland oolite. These sections will show at once the general accordance of the characters of this irregular oolite, its variable thickness, and indefi- nite order of succession, circumstances which belong indeed more or less to all the oolitic formations. The corals which characterize the rock lie very unequally, yet perhaps we may perceive a tendency to form two layers, one near the top, the other at the bottom of the rock. The Oxford series seems imperfect by the deficiency of the upper members, a circumstance probably connected with ancient denudations, by which also this rock has been greatly affected in different parts of Yorkshire. Upper Caic Orit The upper calcareous grit, obscurely indicated at Weymouth, and very thin and unimportant in Wiltshire (where it appears separated from the oolite by ferruginous clay), is of con- siderable note along the north side of the Vale of Pickering, espe- cially about Helmsley and Hackness. It then reaches even a thickness of 60 feet, and by intercalating its upper part with the Kimmeridge clay establishes a transition from the middle to the upper oolite formation. It is in general more ferruginous and less cherty than the lower calc grit, and in Yorkshire contains apparently fewer organic remains, but of the same kinds. It has been entirely removed by denudation from the oolite cliffs of the coast. At Wey- mouth its fossils are numerous and fine. Upper Oolite Formation. The upper or Portland oolite formation, consisting of limestone above and clay below, might be expected to occupy a country whose physical geography should strongly resemble that of the district of coralline oolite. The area occupied by the calcareous group is in- deed so very small in England, that little can be said on this point concerning it. Its commanding appearance in Portland Isle, in the Vale of Pewsey, at Swindon, and in the Vale of Aylesbury, is ana- logous to that of the oolitic rocks in general, and the sands with which it is in some places associated, increase this resemblance. Kimmeridge Clay. The Kimmeridge clay in its much longer and more connected range in Dorsetshire, Wiltshire, Berkshire, and Buckinghamshire (where, though growing thinner, and with dimi- nishing area, it can be traced at least as far as Little Brickhill), and TJPPEE OOLITE EOEMATION. 311 beneath the wolds of Lincolnshire, and through the Yale of Pick- ering in Yorkshire, presents the usual characters of a thick clay deposit, broad vales with a cold, stiff soil, without springs. The Kimmeridge clay, at its typical locality in the Isle of Pur- beck, appears in the cliffs as a laminated clay, bluish or grayish- yellow, dividing spontaneously like other shales into large tabular masses, the joints often lined by calcareous spar. Layers of small argillaceous nodules occur. It passes gradually into a bituminous shale, imperfectly combustible, and finally into layers of brown shaly coal, of specific gravity only 1'319, which burns with a smoky yel- lowish flame. Alum was formerly manufactured from these shales. The group is supposed to equal 600 feet in thickness. (Geology of England.) Insects have been found by Brodie in Kimmeridge clay. In the Vale of White Horse at Even Swindon, it was penetrated by a well to the depth of 233 feet, and the additional thickness of the incumbent beds in Swindon Hill being taken at only 70 feet, the stratum will appear 300 feet thick. Near Oxford it is only 100, and at Bagley Wood was found only 70. In Lincolnshire and Yorkshire its thickness generally appears much less through the unconformity of the chalk strata. Near the bottom of the Kimmeridge clay in the Yale of White Horse, below the layers of ostrea delta, was found a band of coarse oolitic ironstone with fossils, and besides this occurred laj'ers of sep- taria, with ammonites, trochi, and many other fossils much allied to those of the coralline oolite. Shale and bituminized wood were found at about the middle of the clay, and above this a course of thin balls of stone with mineral water. Near Weymouth the lower part of the clay contains, above large beds of ostrea delta, beds of ferruginous impure calcareous grit, partially oolitic, and alternating with beds of red and green sand and blue clay containing ostrea delta. Small bands of calcareous grit may be seen in the lower part of the Kimmeridge clay of Yorkshire, below layers of ostrea delta. It thus appears that the remarkable species of oyster so named by Mr. Sowerby is a very characteristic fossil of the lower parts of this clay group, and its manner of occurrence is equally so. For whether in Yorkshire, at Helmsley, Kirkby Moorside, Ellough- ton, &c., in Lincolnshire at Market Rasin, at Little Brickhill in Buckinghamshire, at Heddington near Oxford, at Even Swindon and Pewsey Yale in Wilts, or at Weymouth, and we may add, from per- sonal observation in 1829, at Havre, it always appears in broad con- tinuous floors, parallel to the planes of stratification, the valves usually together, with young ones occasionally adherent to them, and entirely embedded in clay, without nodules or stones of any kind, and without any other organic remains in the layers. Portland Oolite, &c.The upper oolite group consists, like those 312 MIDDLE MESOZOIC STEATA. previously described, of a variable mass of sand and sandstone con- cretions, surmounted by a partially oolitic, shelly limestone. Were the rock to be seen more completely, it is probable that it would also show a less definite arenaceous zone above. In Purbeck it is covered by the fresh water or Wealden formation, and in Wiltshire, Berkshire, and Buckinghamshire by a feeble representative of the Wealden, or by the lower green sand. The varieties of composition in the limestone are such as have been noticed for the other oolites, viz. fine grained white oolite, loose granular limestone of earthy aspect, and compact cretaceous lime- stone with conchoidal fracture. In the Island of Portland the groups present, according to Web- ster (Geological Transactions), the following characters : {Stone brash, a cream-coloured limestone 3 Feet. Upper beds 4 Parting of the same with black clay 1 " f Cap stone, in three layers with partings of clay cream- l_ coloured and hard, so as to turn the points of the tools. 10 I Roach, a rock composed of fragments of oyster shells ce- mented together 6 White beds, marketable stone 5 Layers of flint and stony rubbish 6 Middle beds... Middle bed, marketable stone, with few marine im- pressions 5 Parting stone with shells of no value 2 Third bed with few shells, generally the most saleable freestone ." 7 to 14 Lower beds ~Many layers of flints and of unserviceable stone 50 to 60 Still lower, according to Buckland and De la Beche, is a bed of sand and sandstone 80 feet thick, with green grains, and very like to the lower green sand. At Chicksgrove, in the Vale of Tisbury, Wilts, the series of lime- stones, more or less associated with sand, especially in the lower part, reaches more than 60 feet in thickness. Miss Benett, who has extracted so many treasures from those quarries, has given a minute section of the beds. The five upper beds, amounting to 29 feet, consist of white limestone, locally called chalk, with one interposed layer of bad shelly stone, and a band of cherty flint 4 inches thick. The middle bed of this limestone, 2 feet thick, is excessively rich in shells, but the thicker beds above and below contain none. The next three beds of the quarry, amounting to 10 feet, consist of sandy limestones, with fragments of shells. Five beds below consist of sandy limestone, mostly compact and shelly, with grains of green sand in greater or less abundance. The three lowest beds are composed of loose sandy limestone, with more or less of the green grams before noticed, shells and fragments of shells. The shells most abundant at Chicksgrove are trigonise, pectines, ammonites, cardia, trochi, &c. WEALDEN FOEMATIOtf. 313 &c. The imperfect sections at Brill Hill and Garsington present several points of analogy with the above section, especially in the presence of the cretaceous bed, and the quantity of sand below the calcareous part of the rock is well seen here and at Shotover, where it encloses in the lower part large, grotesque, concretionary blocks of sandstone, sometimes full of shells, and generally abundant in green grains. Abundance of green grains accompany these lower beds in their course through the vale of Aylesbury, and are also recognized at Swindon. The height of the ground occupied by the detached portions of the upper oolite group is considerable in Brill Hill, (780 feet,) in Shotover amounts to 583 feet, at Swindon probably 400 feet, in Portland 300 feet, but in the Vale of Pewsey it is very low. irt Bed of Portland. One of the most interesting observations concerning the circumstances which intervened between the marine deposits of oolite and the fresh water or estuary deposits of the Purbeck clays and limestones, is that of Buckland and De la Beche on the dirt bed which lies between these groups of strata in the Isle of Portland. This bed is compared by those acute geologists to black vegetable mould. The stems of cycadese and larger coniferse, which are found in this bed, often " stand erect, and have their roots attached to the black soil in which they grow ;" thus presenting us with an ancient submerged forest, for comparison with the more modern submarine forests which in so many points margin the English, Welsh, Scotch, and Irish coasts. It is concluded by these authors that the Portland rock, whereon these plants are stated to be in the place and attitude of growth, had been raised to become dry land, and then sunk again, under such circumstances as to become covered by fresh water, which produced the Purbeck limestones and clays; and it appears a matter of probable inference that at the same periods the whole Wealden district was submerged under nearly the same circumstances. The absence of conglomerates and dislocations appears to prove that these submersions were effected quietly and gradually: certain beds of oysters show that the waters were at least occasionally brackish, the sea again regained its dominion, and deposited the cretaceous rocks and marine testacea, and finally yielded place again to a lacustrine deposit. Wealden Formation. Until the appearance of Mantell's excellent works on the geology of Sussex, the peculiar relations of the vast thickness of sandstones and clays of the interior of Kent, Sussex, and Hampshire, were mis- 314 MIDDLE MESOZOIC STEATA. understood. No one supposed that these immense strata were alto- gether of a peculiar type, and interpolated amidst the rest of the marine formations, as a local estuary formation, of which only very faint traces can be perceived in other parts of England. Always striving to make particular results harmonize into one general system, Smith and other geologists at one time referred the interior sand- stones to the "iron sand," and the Weald clay to one of two beds, confused under the title of oak-tree clays. This mode of classification seemed, indeed, tolerably consistent with the mineralogical characters of the formations, but was found wholly at variance with their animal and vegetable remains. For these, instead of being fossils of the iron sand and Kimmeridge clay or gault, were really a peculiar suite of terrestrial and fluviatile exuviae of which very few traces have been perceived elsewhere. Man tell 's publications, followed by many other writings, have clearly shown that the true place of the strictly Wealden formations is below the iron sand or lower green sand, and immediately above the Purbeck limestones, which overlie the Portland oolite. The only places in England where analogous beds are known to occur, are at the back of the Isle of Wight, in the Isle of Purbeck, along the south side of the Dorset Downs, in the Vale of Tisbury in Wilts, and below the range of the chalk hills of Berkshire and Buck- inghamshire. Groups. The Wealden formation naturally divides itself into two groups, which give distinct physical features to the countries which they occupy : and if to these we add the Purbeck limestones below, we have the following order of succession : ,, f Pale blue clay, of considerable but variable thickness, having in w^u ^T U P* -s the upper part septaria of argillaceous ironstone, and in the ( lower part beds of the shelly limestone, called Sussex marble. ' Fawn-coloured sand and friable sandstone. (Horsham beds.) Calciferous sandstones, alternating with friable and conglomerate grits, resting on blue clay. (Tilgate beds.) Middle group, i White sand and friable sandstone, alternating with clay. (Worth Hastings sands. \ sandstone.) Bluish-gray limestone alternating with blue clay and sandstone shale, and some beds of calciferous sandstone. (Ashburnham beds.) , (The Purbeck beds, consisting of shelly limestones alternating with The Weald clay forms one general valley, most conspicuous on the northern side, between the elevated central ridges of the Hastings sands, and the chalk downs of Kent, Surrey, Hampshire, and Sussex, from Hythe by Tunbridge, Hartingcombe, Hailsham, to Pevensey. The Hastings sands distinguish themselves by forming a central axis of elevation along what is called the Forest ridge, by Battle, WEALDEN FORMATION. 315 Crowborough, and Tilgate Forest to Horsham : Crowborough, the highest point, is 804 feet above the sea. This arrangement may be studied on Mantell's and Smith's sections, but the general axis of elevation is so confused by a number of local disturbances, and is, moreover, so broad a ridge, that its character is often overlooked. Those who suppose the chalk of the northern and southern escarp- ments to have once extended over all the area of the Wealden forma- tion, and to have been subsequently removed by watery violence, have rightly applied to this devastated region the name of the great denudation. A decided analogy prevails between the upper part of the Purbeck series and the marble beds of the Weald clay. We shall now add a few details on these groups in succession, beginning with the Purbeck beds. Purbeck Beds. These consist of many thin strata of argillaceous limestone, alternating with slaty marls, and form an aggregate of 300 feet in thickness. Webster describes the beds of stone as con- sisting chiefly of shells, usually, and with much probability, referred to the fresh water genus paludina. A small portion of these calcareous beds is fit for columns, chimney-pieces, and other architectural uses, for which the " Purbeck marble " is celebrated. Our cathedrals were formerly supplied from quarries in the very highest part of the series, which are now extinct. The shells in this stone are usually small paludiniform shells. According to Mr. Middleton three veins of good stone, not exceeding altogether 17 feet, lie in the midst of alternations of other stone compact or shelly, and black slaty clay, more than 270 feet thick. We are indebted to many geologists, following the indications of Webster, for notices of the strata of Purbeck, and the district has now been surveyed by the geologists who follow the standard of De la Beche. To Dr. Fitton's enumeration of the fossils of the fresh water beds, Professor Forbes added a large series of newly discovered forms, and described the curious circumstances by which they are accompanied. The lowest Purbeck fresh water beds, 8 feet thick, appear suddenly upon the Portland marine beds. They contain Cyprides, Valvata, and Limncea. Above these is the great dirt bed, with stools of Cycadece ; another dirt bed occurs above ; cypridiferous shales follow. Twenty or thirty feet of shales, laminated marls and limestones, with occasionally siliceous bands, follow, filled with Eipoae and small Cardia, the denizens of brackish water. Purelv fresh water marls come on above with the same groups of fossils as those below. Greenish shales with Zosteracese and marine shells succeed. New fresh water beds succeed, with Cypris, Valvata, Paludina, Planorbis, Limncea, Physa, and Cyclas, all different from what were seen below. Gyrogonites occur here in cherty stone. 816 MIDDLE MESOZOIC STEATA. Next above is the cinder bed, full of Ostrea distorta; here occurred Hemicidaris Pur- beckensis, and a Perna. Mixed marine and fresh water beds succeed, with fishes, reptiles, &c. Then followed a more decided sea inroad, with Pectens, Modiolce, Aviculce, and Thracice, all undescribed forms. Brackish water strata full of Cyrence, with bands of Corbulce and Melanice, are next in order; cyprides, turtles, and fish, crown these bands. Lastly, a third series of fresh water strata commence with a new series of fossils, Cyprides, Paludince, Physa, Limncece, Planorbes, Valvatce, Cyclades, Uniones, and fish. These continue till they merge into the base of the Hastings sands. So similar to living species are the fresh water shells of Purbeck, as to be hardly distinguishable from them. The whole series is about 155 feet thick.* These deposits have yielded many insects, fishes, and reptiles, and one mammal, Spalacotherium.^ Ashbin itiiaiu Beds. The Ashburnham beds, above 100 feet thick, consist of shelly limestone and shale, alternating with blue clay, and containing subordinate beds of ironstone and sandstone. Limestone, of a dark bluish-gray colour, full of immense quantities of bivalve shells, more or less spathose, is the most characteristic deposit of the group. The shale which is associated with this limestone, sometimes contains the same shells in a white friable state. In ancient times the rich ironstone accompanying this limestone was, through the use of the latter as a flux, converted into iron by wood fires, and thus, in part, have the vast forests of Sussex been diminished. The shells are usually supposed to belong to cyrena or cyclas, in accor- dance with the opinion that the whole Wealden formation is of fluviatile'or estuary origin At Poundsford a bed of calciferous Til- gate sandstone is found under a bed of the Ashburnham limestone, and the same was found in some of the limestone pits of Lord Ash- burnham. worih Sands. The Worth sands and sandstones afford a fine soft building-stone, extensively dug at Worth, near Crawley. The sand- stone is for the most part of a white or pale fawn or yellow colour, and occasionally contains leaves and stems of ferns, arundinaceous plants, and other vegetable reliquiae. They may be well studied in the cliffs near Hastings. Tiigate Beds. The Tilgate beds consist of three divisions. The lower one is clay or marl, of a bluish-gray colour, alternating with sand, sandstone, and shale, and containing stems of vegetables, and very rarely bones and shells. The middle division consists principally of large concretional or lenticular masses of a compact calciferous grit, or sandstone lying in sand. The stone is fine grained, of a light gray colour, inclining to blue or green, and is composed of sand, cemented together by about * Forbes in Reports of British Association, 1850, pp. 79-81. f Owen in Geological Journal, 1854. WEALDEN FOBMATION. 317 25 per cent, of crystallized carbonate of lirne. Its fractures frequently show glistening faces. The lower portions of this bed form a con- glomerate, and contain pebbles of quartz and jasper, sometimes evidently water-worn. (Of this stone are three or four layers, from 2 or 3 inches to 1J or 2 feet, associated with sand.) The surface of the blocks is often covered with mammillary concretions. These are the strata from which Mr. Mantell has drawn the astonishing pro- fusion of animal and vegetable remains. The vegetables are wholly of terrestrial origin, mostly of cryptogamous and gymnospermous structure. There are probably no zoophytic remains. The testacea (mostly casts) much resemble the lacustrine genera, paludina, unio, cyrena. Fish teeth and scales abound, with remains of a land tortoise, a fresh water and a marine turtle, plesiosaurus, crocodile, megalosaurus, hylseosaurus, iguanodon, and some kinds of aquatic birds. Irregular alternations of sand and sandstone, of various shades of green, yellow, and ferruginous, the surface often furrowed like the sand on the sea shore, cover the whole group. Horsham Beds. The Horsham beds of sand and friable sandstone, gray, yellow, or ferruginous, with occasional interspersions of iron- stone, and a very large proportion of disseminated small linear por- tions of lignite, form the upper division of the Hastings group, and encircle the immense Tilgate beds. The sandstone is micaceous and ferruginous, and sometimes holds a considerable proportion of cal- careous matter. These beds alternate with a stiff gray loam or marl. The lignite is conjectured to have been derived from carbonized ferns. Weald Clay Group. The Weald clay group, besides its general physical features already mentioned, has little to detain us. The septaria of this clay are composed of a deep red, argillaceous ironstone, and with remains of fishes and cyprides, occur in layers of two or three feet in thickness in the upper divisions of the clay. The shelly limestones, so well known by the name of Sussex marble, appear to occupy chiefly the middle beds of the Weald clay. They occur in layers of a few inches or a foot in thickness, separated from each other by seams of clay or coarse friable limestone. The compact varieties, when polished, exhibit sections of the enclosed shells. These are usually referred to paludina, and have been compared to the recent paludina vivipara, and they are associated with the shelly remains of a minute branchiopode, (cypris,) from which circumstance it is inferred that the Weald clay is a lacustrine deposit. This shelly marble occurs all along the line of the Weald clay from Leighton to Petworth, Newdigate, South of Tilvester hill, and Bethersden in Kent : potamida ? and cyrenae have been collected from this clay. Insects have been found in it by Messrs. Binfield. 318 MIDDLE MESOZOIC STKATA. Fresh Water, Origin of. The evidence upon which it is now very generally admitted that the Wealden formation was a fresh water or estuary deposit, is founded upon a contemplation of the organic remains, and this subject admits of three general observations. First. There is in all the strata of the Wealden formation, whether sandy, argillaceous, or calcareous, an almost entire absence of decided marine genera of shells and zoophyta. In particular, the numerous and characteristic tribes of ammonites and belemnites, of trigonise, terebratulae, and ostreae, of echinida, stellerida, and polyparia, are entirely absent from almost every bed, a circumstance certainly unparalleled in any section of equal variety among marine strata. Secondly. What shells there are have most generally the forms of fresh water or littoral genera, and it may be remarked especially that this kind of evidence bears with equal force upon all the groups. Thirdly. The plants which abound in this middle group are of terrestrial, or marshy, and not of marine origin, and the saurian remains also indicate the littoral or marshy life of those monstrous animals. The recently discovered land mammal, Spalacotherium, cannot be admitted in evidence. We may therefore confidently adopt MantelTs conclusion of the fresh water origin of the materials of the Tilgate beds, and suppose these materials to have been deposited in an estuary by one or many rivers ; the lower beds of limestone and clay, and the upper group or Weald clay appear to demand partly limestone and partly brackish, rather than marine conditions. The materials of these argillo- calcareous deposits were also derived from the land, but not by the same processes or in the same manner as the arenaceo-calcareous deposits of the forest ridge. Whatever may have been the causes, it is probable that the change from the truly marine Portland oolite to the partially lacustrine Purbeck beds was not the fruit of a violent convulsion, but the result of easy and even intermittent operations, such as general vertical movements of the sea bed might bring about. In a great part of the oolite deposits we find traces of a neighbouring land ; in several the phenomena of fresh water lagoons, opened at intervals to the sea, in others, the deposits of great rivers filling up an estuary. We require nearly all the varieties of alternating sea and fresh water action to understand the great Wealden forma- tion. Oolitic System. Foreign Localities. Range and Extent. The oolitic system is so largely developed in England as to form a very conspicuous, if not the principal feature in its physical geography, and its extreme ramifications reach the northern and western coasts of Scotland and the eastern shore of OOLITIC RANGE FOREIGN LOCALITIES. 319 Ireland. But the range of these rocks is still more extensive on the continent of Europe, and indications of the continuation of the lower formation of lias occur in North America and are repeated in India. In France a broad belt of oolitic rocks borders on the east the primary rocks of Brittany and La Vendee, and sweeps round the basin of Paris from the coast of Normandy (Calvados), by Falaise, Alen9on, Lemans, Saumur, Poitiers, Chateauroux, and Nevers, and through Burgundy, Franche-Comte, and Lorraine, till, along a line from Avesnes to Luxemburg, it abuts against the slate mountains of the Ardennes. From Poitiers the oolites continue themselves west- ward to La Eochelle, southward to Angouleme, Perigueux, Cahors, and the vicinity of Montauban. A little discontinuity here occurs ; but the oolites of Rhodes and the Cevennes mountains, by prolong- ing themselves south-westward to Montpelier, Carcassone, and Foix, along the northern slope of the Pyrenees to Fontarabia, and north- eastward to Montelimart and Grenoble, and so to the Jura, and south-eastward to Marseilles and Nice, unite into one irregular mass the whole area of the French oolite. These formations are largely developed in Spain, and, in particular, form a band on the slope of the Pyrenees. Along the Swiss border of France runs the long calcareous chain of the Jura, and this whole mountain region is a mass of the oolitic rocks. It is therefore generally assumed on the continent as a type of the system ; and the terms Jura-kalk, Jura formation, are exactly equivalent to our oolitic system. This is connected below the allu- vial valley of the Saone with the oolites of Burgundy. In its con- tinuation northward, the Jura ranges pass in a broad belt through Wurtemberg, Bavaria, and Franconia, and reach the Maine as it issues from the Bohemian mountains. The Jura is also connected, by crossing the Rhone below Geneva, with the limestone which follows the range of the Western Alps from Provence through the Tarentaise and Savoy into the Valais, and continues along the Oberland mountains, across the Lakes of Thun, Brieritz, Lucerne, and Wallenstadt, and then beneath the Tyrolese and Styrian Alps, by Inspruck and Salzburg to the neigh- bourhood of Vienna. Nor is this the end of the enormous range, for the northern border of the Carpathians about Cracow and Dynow is denned by vast breadths of compact oolite. On the southern side of the Alps the same limestones appear in great force, and stretch through Illyria and Carniola to Trent, and the Lakes Guarda, Iseo, Como, Lugano, and Maggiore. Besides these immense ranges of rocks of the oolitic era, many smaller detached portions may be seen upon Von Buch's and other maps, and one in the northern part of France, around Boulogne, is of particular interest, in connection with our Wealden. 320 MIDDLE MESOZOIC STRATA. It appears, then, that the sea which deposited the oolites floated round, or perhaps covered the spaces where now rise 011 high the Alps, the Carpathians, the Pyrenees, Auvergne, the Vosges, the Black Forest, and Bohemian mountains, in general corresponding to the basin in which the saliferous system was formed. The original arrangement of the rocks has been in places immensely disturbed, and vast regions have been devastated by floods, yet no doubt the general geographical outlines of the system are nearly what they always were. It may not be easy always, in the present state of knowledge concerning the extent of subterranean movements, to say what were the depths and the shallows of this great ocean ; but even toward this very considerable approximations may be made by com- paring the mineral, and zoological, and botanical characters of the deposits in different places. Divisions of the System. Notwithstanding their vast extent, it does not appear that the continental oolites are anywhere subject to greater variation of composition than the English series. In the north of France most of the groups acknowledged by the English geologists may be recognized, as the lias, inferior oolite, Bath oolite, forest marble, Oxford clay, coralline oolite, Kimmeridge clay, and even the Portland oolite and Wealden (De la Beche, Geol. Trans.), and the organic remains are either very similar or identical. But in the vicinity of the granites of Auvergne, it is difficult to dis- tinguish more than the lias, and one great overlying mass of oolites indistinctly divided, except by having in the lower part a ferruginous bed sometimes accompanied by ferruginous sand probably corres- ponding to that of the inferior oolite. The Jura shows us distinctly the lias, and a mass of calcareous rocks, sometimes perfectly oolitic, in other places earthy or compact, occasionally interlaminated with clays, but hardly capable of any clear and satisfactory divisions. The lower parts are often ferruginous and sandy, and clearly represent the inferior oolite. The upper parts, nevertheless, by admixture of chloritic grains and beds of green sand, appear to represent the upper oolite series of England, until, as may be particularly observed in the Sale^ve, it is difficult not to allow that some characters of the oolitic and cretaceous systems are united in the cap beds of the Jura-kalk. This should be compared with the previous notices of green sand below the Portland oolite, and remem- bered in discussing the "neocomian" system. The fucoid grits along the line of the Eastern Alps clearly belong to the green sand. The relations of the hippurite limestone, which is at the top of the Alpine kalkstein, show that the causes which in England and the north of France have occasioned such decided differences in the oolitic series, and established so many groups, did not obtain in these parts. It is extremely probable that this is merely the difference between DIVISIONS OP THE OOLITIC SYSTEM. 321 littoral and pelagian deposits. In England, generally, the distur- bance of a shore is indicated by the more numerous alternations, beds of clay and sandstone, rolled shells, ripple marks, and land plants ; and, where these characters go to extreme, the whole forma- tion appears changed to a coal system. Something like this hap- pens, as before mentioned, at the Porta Westphalica ; but the greater part of the oolitic limestone of France, Germany, and the Alps appears to have been deposited in deeper and more quiet waters. Through all these countries the proportion of limestone to the more mechanical deposits is much greater than the average of the English series, the marks of disturbance are mostly wanting, the lines of division are obliterated, and the products of the land infrequent. Perhaps we may in this way account for the smaller number of organic remains belonging to the Alpine limestones ; for if these were eminently pelagian, they should probably contain fewer marine exu- viae ; since we have good reason to believe that the deepest parts of the sea, where light can hardly penetrate, and all is dull repose, are almost devoid of organic life. As the borders of a desert are rich in every vegetable hue, and resonant with all the voices of animals, so are the borders of the sea prolific of existence, but the Sahara and the ocean are equally dead at their centre. The oolitic texture seems to lose itself in the same manner toward the Alps, amongst which it can be seldom seen ; and in general the paucity of organic remains is greatest in the most compact or most crystalline of the varieties of these limestones. The Jura, through its whole range in Wurtemberg and Bavaria, uniformly shows upon the lias a cap of rocks associated with sand, and often passing up- wards into ferruginous oolite, and the same thing happens above the lias of Hanover and Westphalia. Soienhofen Beds. In the centre of the German Jura, at Solenho- fen and Eichstadt, occur beds of white fissile limestone, now univer- sally employed in lithography, which abound in organic remains, and have been long supposed to be much related to the Stonesfield slates. This relation is, perhaps, not supported by their geological position ; for this is certainly above not only the inferior oolite pre- viously described, but also above a considerable thickness of Jura- kalk and a variable mass of dolomite. M. Von Dechen appears to think these beds of an anomalous character, as indeed their organic remains testify. The whole of this slaty group is seen to thin out near the mouth of the Altmiihl between masses of dolomite, being entirely surmounted by green sand and cretaceous deposits. (Mur- chison, Geol. Proceedings) The author just quoted inclined to the opinion that the higher members of the oolitic groups of England had not been satisfactorily denned in any part of central Germany. T 322 MIDDLE MESOZOIC STRATA. Disturbances of the Oolitic System. The parallelism of beds over large regions, the repetitions of similar rocks at frequent intervals, and the gradual change of the species of organic remains through the whole series, appear to indicate that the long period when the oolitic system was deposited was one in which the ordinary operations of nature were uninterrupted by pa- roxysms of igneous violence. On viewing the whole series of these strata, and considering the manner in which their outcrops follow one another, it appears that only a very few instances can be pointed out where any beds of the oolitic system are really unconformed to others of the same system below them. Apparent exceptions to this 1 law are indeed presented by every detailed geological map, particu- . larly in the case of the coralline oolite, but this rock appears to have been an irregular and limited deposit. It is, perhaps, hardly enough ; to justify the term unconformity, to show that some of the upper ^ beds of this system have probably been removed by wasting effects I of water before the deposit of the incumbent clay, as at Heddington. 1 One case, however, may be mentioned, at Cave, in Yorkshire, where, 1 amidst the more striking phenomena of unconformity between the I oolitic system and the chalk, there appears reason to believe that I the deficiency in cornbrash and forest marble systems may be ascribed $ to a local unconformity of the stratification of the Kelloway rock. | Other instances will no doubt be discovered, but they will probably 1 be found equally unimportant. The case, however, is entirely different, when we transport our- 1 selves to the period immediately following the deposit of the oolites. Through a large part of England the line of the outcrop of the chalk, green sand, &c., follows pretty exactly the range of the oolitic sys- tem ; and of course we must infer that for all those districts the bed and boundary of the sea were not materially changed, except by gra- dual purely vertical movement of the earth's crust in the interval between the two systems of strata. But at either extremity of the range the plane of the cretaceous system is carried over the edges of the oolites from the upper to the lower part of the system, so that at Bishop Wilton, in Yorkshire, it rests within 25 feet of the top of the red marl. In Dorsetshire, the chalk and green sand, by over-extension, rest on all the members of the oolite in succession, and at length, in Haldon, actually touch the red marl. Murchison, from his interesting observations on the Ord of Caith- ness, inferred that this granitic mass had been upheaved in a solid forrrt, and thus that the contiguous or neighbouring oolitic strata DISTUEBANCES OF THE OOLITIC SYSTEM. 323 were broken up. The brecciated character so frequent in these lime- stones is referred to a subsequent recomposition of the fragmented parts. Without dwelling on other cases in the British dominions, we may fairly infer from this important observation, coupled with the former cases, that there was an extensive disturbance and angular movement in the interior of the earth beneath the sea in which the oolites had been deposited. Considerable faults, ranging E.S.E. and N.N.W., accompany the elevation of the oolites in Yorkshire. On the continent very extensive disturbances, happening at the same era, show that this was indeed a period when the convulsive energies of the subterranean regions were strongly and extensively exerted. To this period M. Elie de Beaumont refers a very extensive line of dislocations, connected with the elevation of Mont Pilat near Lyons, the C6te d'Or, and the Erzgebirge. It is observed that all these axes of elevation range north-eastward and south-westward, and in the regions intermediate between these, marking ridges and lines of undulated stratification may be traced in the same north- eastern and south-western direction, particularly on the broad belt of the Jura. Without insisting upon the exact parallelism ascribed by M. de Beaumont to these lines of disturbance, we are warranted in admit- ting that to the convulsions at this period the long range of oolites connected with the ridges of the Jura both in France and Germany, and with the line of the Erzgebirge, owe, if not their actual height above the sea, some of their peculiar physical features. The creta- ceous system in the vicinity of these lines of disturbance appears to be unaffected by them, except by the new outlines which were then given to the embosoming ocean within which at a later period the chalk, green sand, &c., were deposited. The oolites which pass north-westward from Lorraine are probably continuous under the whole of the chalky plains of Picardy, but their superficial outcrop is extinguished by the over-extension of the chalk to contact with the slates of the Ardennes, nor is it renewed on the northern side of those mountains. Yet this case may not happen through any unconformity, but be a consequence of the irre- gular bed of the ancient sea. Thus, the red sandstone may be covered and concealed by the oolite, and the latter may be hidden below the chalk, and yet there may be no unconformity. This view is supported by the successive coming out in proceeding to the south-east from Avesnes, first of the oolite, then of the keuper, muschelkalk, and red sandstone, from their abutments against the older strata. 324 MIDDLE MESOZOIC STEATA. ORGANIC REMAINS MIDDLE MESOZOIC SYSTEM. [The genera supposed to be confined to Mesozoic strata are in small capitals. Foraminifera and Insecta are excepted from this rule.] PLANTS. HALYMENITES, No. of Species. 2 Lias. L. Oolite. M. Oolite. ACROSTICHITES, Alethopteris, BAIERA, CTENIS, Cyclopteris, Dictyophyllum, . Hymenophyllites, LONCHOPTERIS, OTOPTERIS, PACHYPTEKIS, . Pecopteris, PHLEBOPTERIS, . POLYPODITES, POLYSTICHITES, . SAGENOPTERIS, . SCHIZOPTERIS, . Sphenopteris, TJENIOPTERIS, 1 1 1 1 3 1 2 2 3 2 14 2 2 1 2 1 12 5 1 1 8 1 2 1 2 2 (4 2 2 1 2 1 8 5 Equisetites, . Lycopodites, EQU1SETACEJS. 512 LYCOPODIACE^E. 1 1 Endogenites, Lilia, MONOCOTYLEDONE^E. 1 1 1 ARAUCARITES, . BRACHYPHYLLUM, CRYPTOMERITES, Cupressus, . DAMMARITES, Peuce, Pinites, TAXITES, . THUYTES, . CONIFERS. 1 1 ... 1 ... 1 1 ... 1 1 1 ... 1 ... ... 3 2 1 1 ... 1 1 ... 1 5 ... 4 GENERA OF ORGANIC REMAINS. 325 Walchia, (Wood), No. of Species. Lias. L. Oolite. M. Oolite. U. Oolite. Wealden. 1 1 BUCKLANDIA, CLATHRARIA, CYCADEOIDEA, . PAJ^EOZAMIA, PODOCARYA, PTEROPHYLLUM, . ZAMIOSTROBUS, . ZAMITES, . (c) Carpolithus, . (c) Strobilites, . Chara, TYMPANOPHORA, SPH^EROCOCCITES, SPH^REDA, . BENSONIA, . STRICKLANDIA, . Calamites ? NAIADITES, SALICITES, SOLENITES, MANON, Scyphia, Spongia, TALPINA, 1 ... 1 1 ... ... 3 i ... 9 2 "7 1 ... 1 5 ... 4 3 "3 7 ... 4 1 1 ... CHARACE^E. 2 ... ... 2 ... "2 2 1 1 1 ... 1 1 ... 1 1 ... 1 1 ... 1 4 2 2 1 ... 1 2 ... 2 AMORPHOZOA. 1 ... ... 1 ... ... 5 ... "i 1 ... 1 FORAMINIFERA. Bulimina, . Cristellaria, Flabellaria, Frondicularia, Gaudrj T ina, . Lituola, Marginulina, Nodosaria, . Polymorphina, Rotalina, Spirolina, . Vulvulina, . Webbina, . ZOOPHYTA. ANABACIA, . AXOSMILIA, ZOANTHARIA. 326 MIDDLE MESOZOIC STRATA. No. of Species. Lias. L. Oolite. 31. Doli CALAMOPHYLLIA , 1 1 CLADOPHYLLIA, . 2 2 ... CLAUSASTRJSA, . 1 1 ... COMOSERIS, ; 2 1 1 C ON VEXASTR.E A , .1 1 ... CYATHOPHORA, . 2 2 ... DlSCOCYATHUS, . 1 1 ... EUNOMIA, . 1 1 GONIOCORA, 1 1 IsASTRjEA, . 12 "s 8 LATOMEANDRA, . 2 2 MlCROSOLENA, 3 3 ... Millepora, 1 1 MONTLIVALTIA, . . 12 11 1 PRIONASTR^EA, . 1 1 ... PROTOSERIS, 1 1 RHABDOPHYLLIA , 1 ... 1 STYLINA, . 5 3 2 THAMNASTR^EA, . . 15 12 8 THECOSMILIA, 2 1 1 Trochocyathus, . 3 2 1 ... Zaphrentis, . 1 1 ... ECHINODERMATA. ECHINOIDEA. ACROSALENIA, Cidaris, Diadema, . DISASTER, . Echinopsis, Echinus, GONIOPYGUS, HEMICIDARIS, HOLECTYPUS, HYBOCLYPUS, NUCLEOLITES, PYGASTER, PYGURUS, . 8 12 8 4 2 6 1 8 2 4 12 7 6 4 8 2 5 1 6 2 3 10 2 2 Astropecten, LUIDIA, SOLASTER, . TROPIDASTER, Uraster, ASTEROIDEA. 6 3 1 1 1 1 1 1 1 AMPHIURA, ASPIDURA, OPHIODERMA , Ophiura, OPHIUROIDEA. *1 8 1 GENEKA OF ORGANIC EEMAINS. 327 CRINOIDEA. No. of Species. Lias. APIOCRINUS, . . 4 BOURGUETICRINUS? . 1 EXTRACRINUS, 2 2 MlLLERICRINUS, . 2 Pentacrinus, 9 5 L. Oolite. M. Oolite. U. Oolite. Wealden. 4 1 Serpula, Vermicularia, Vermilia, . ANNEMDA. 2 16 2 1 Pollicipes, . CIRRIFEDA. ARCH./EONISCUS, Astacus, COLEIA, CYPRIDEA, Cypris, ESTHERIA, . GLYPHIA, . MECOCHEIRUS, CRUSTACEA. 1 2 1 1 I IN SECT A. Berosus, Carabus, Cerylon, Coccinella, . Colymbetes, Curculionides, Cyplion, Elaterium, . Gyrinus, Helophorus, Laccophilus, Limnius, Melolontha, Prionus, Rhyncophora, Curculiuin, Buprestium, Blapsium, . Harpalidium, Tentyridium, Agrillium, . Helopidium, Telephorium, Ctenicerium, COLEOPTERA. 1 1 ... 2 ... ... 1 ... ... 1 ... 1 1 ... i ... 1 i ... ... 4 1 ... 1 1 ... 1 ... ... 1 1 ... 1 ... ... 1 1 ... 1 ... 1 1 ... .. i 1 ... ... 7 ... ... 1 ... 1 2 ... ... 1 ... ... 4 ... ... 2 ... 1 ... ... 2 ... ... 328 MIDDLE MESOZOIC STRATA. NEUROPTERA. No. of Species. Lias. Agrionidium, Chauliodes, . Corydalis, . Hemerobioides, Leptocera, . Libellulium, Lindenia, . Orthophlebia, Phryganea, Termitidium, Panorpidium, Phryganidium, Raphidium, Sialium, . Asilum, Chironomum, Corethrium, Simulidium, Tanypium, Cecidomidiura, Culicium, . Empidium, Macrocercium, Macropezium, Platyura, . Rhyphus, . Sciophila, . Aphidium, Cercopidium, Asiracum, Cicadellium, Cixium, Cimilidium, Delphax, Nepadeum, Kleidocerys, Ricania, Blattidium, Gryllidium, Achitidium, Myrmecium, 4 2 2 1 1 1 1 ... 1 i 2 i i 1 ... S 2 1 ... 1 1 1 ... 2 ... 1 ... ... 1 ... 1 ... ... 1 DIPTERA. 1 1 2 ... ... 1 ... 2 ... 1 ... ... 1 ... 1 ... . . 1 ... 1 ... . . 1 ... . . 1 ... 1 ... ... 1 HOMOPTERA. 2 5 ... ... 1 3 1 1 ... 2 1 1 ... . . 1 . . 1 ... . . 2 1 ORTHOPTERA. G 1 2 1 1 HYMENOPTERA. 1 ... 1 ... .. L. Oolite. M. Oolite. U. Oolite. Wealden. 2 1 GENERA OE ORGANIC REMAINS. 329 Cyllonium, LEPIDOPTERA. No. of Species. 2 Lias. L. Oolite. M. Oolite. U. Oolite. Wealden. 2 BRYOZOA. Alecto, ASPENDESIA, Ceriopora, . CHRYSAORA, CRICOPORA, Diastopora, Heteropora, Hippothoa, . Idmonea, Intricaria, . TEREBELLARIA, Theonoa, 1 1 1 1 3 3 3 3 4 ... 4 1 3 3 1 1 1 1 1 1 1 2 1 1 1 1 Crania, Discina, Leptaena, Lingula, Rhynconella, Spkifera, . TEREBRATELLA ? Terebratula, THECIDIUM, BRACHIOPODA. ! 1 1 ! 2 1 5 2 30 5 1 42 5 5 1 9 5 12 1 19 1 28 2 MONOMYARIA. Anomia, Avicula, Crenatula, . EXOGYRA, . GERVILLIA, Gryphaea, . Hinnites, Inoceramus, Lima, . LIMEA, Ostrea, Pecten, PLCUNOPSIS, Pinna, Plicatula, . PTEROPERNA, TRICHITES, Anatina, Area, . 2 ... 1 1 ... 18 5 8 5 ... 3 1 1 1 ... 4 ... 1 2 "3 16 2 13 2 1 14 5 3 5 1 3 ... 3 ... ... 5 1 4 ... ... 25 6 16 7 1 1 ... 1 ... ... 21 ... 11 7 5 34 3 24 9 4 6 ... 6 ... 7 1 4 2 1 4 2 2 ... ... 4 ... 4 ... ... 2 ... 1 1 DIMYARIA. 330 MIDDLE MESOZOIC STRATA. No. of Species. Lias. L. Oolite. M. Oolite. U. Oolite. Wcalden. Astarte, 23 ... 14 6 4 Cardinia, 11 9 3 1 Cardium, . 20 1 15 1 4 CEROMYA, . 5 ... 5 ... ... Corbis, 5 1 2 2 ... Corbula, . . 3 .. 2 1 ... Cucullsea, . . 17 13 6 Cypricardia, 4 .. 4 ... ... Cyprina, . . 1 .. 1 ... ... Cyrena, . . 12 .. 4 ... Cytherea, . . ". 1 .. 1 ... ... GONIOMYA, , . '. 4 1 3 2 ... GRESSLYA, 6 1 5 ... ... HIPPOPODIUM, . 1 1 ... ... ... Isocardia, . 9 ... 7 3 .. Leda, .... 5 2 2 1 ... Limopsis, 1 ... 1 ... ... Lithodomus, 4 ... 3 2 Lucina, 6 ... 4 2 1 Lutraria, 1 ... 1 ... ... Mactra, 1 ... 1 ... ... Modiola, . 25 6 15 4 1 Mya, . . . 1 ... 1 ... ... Myacites, . 21 2 16 3 1 MYOCONCHA, 3 ... 1 ... ... Mytilus, 4 ... 2 ... 1 Neaera, 1 ... 1 ... ... Nucula, 7 1 5 2 ... OPIS, . 6 ... 5 1 ... PACHYRISMA, 1 ... 1 ... ... Pectunculus ? 1 1 Pholadomya, 24 "5 14 4 1 Pholas, 2 ... ... 1 1 Potamomya, 2 4> 2 ... ... Psammobia, 2 ... 1 ... ... Pullastra, . 2 ... 2 ... Sanguinolaria, 2 1 1 ... SPH-ERA, . 1 ... 1 ... ... TANCREDIA, 6 6 1 Tellina, 1 ... ... 1 ... Thracia, 2 1 1 ... Trigonia, . 30 "i 25 2 4 UNICARDIUM, 5 i 4 ... . .. Unio, . 12 ... 2 ... ... 1 1 10 No Pteropods known. Acteeon, ACT^EONINA, ALARIA, Brachytrema, Buccinum? 5 7 15 2 1 GASTEROPODA. 3 7 13 2 GENERA OF OKGANIC BEMAINS. 331 No. of Species. Lias. L. Oolite. M. Oolite. U. Bulk, 4 2 1 Ceritella, . 9 9 ... Ceritbium, . . 15 11 1 Chemnitzia, . 15 12 2 Cirrus, 3 2 1 Cylindrites. 11 11 ... Delphinula, 6 6 ... DESLONGCHAJIPIA, I . 1 1 ... Emarginula, ,8 3 ... Eulima, 4 4 . . Euomphalus ? 1 1 ... Fissurella, . 1 1 ... Fusus, . 3 3 ... Hydrobia, . 1 1 ... Littorina, . 2 2 1 Monodonta, 7 7 Murex, 1 ... 1 Natica, . 11 .!. 8 3 NERIN^EA, . 17 14 3 Nerita, 5 5 ... Neritina, 2 1 NERITOMA, 1 ... ... NERITOPSIS, 3 3 Paludina, . 4 ... Patella, . 14 .'.. 13 Phasianella, 11 11 1 Physa, 1 ... ... PlLEOLUS, . 2 2 ... Planorbis, . 1 ... Pleurotomaria, . 24 3 16 4 Pterocera, . 3 3 ... Purpurina, . 3 3 1 RlMULA, 3 3 Rissoina, 6 6 ... Solarium, . 4 4 ... SPINIGERA, 2 1 1 Stomatia, . 1 1 TROCHOTOMA, 9 9 ... Trochus, . . 23 1 20 2 Turbo, . 13 1 10 2 Turritella, . 4 1 2 CEPHALOPODA. ACANTHOTETJTHIS, 1 ... 1 AMMONITES, . 209 123 34 45 ANCYLOCERAS, . 2 1 1 BELEMNITES, 27 13 6 7 Nautilus, . . 16 8 8 1 PISCES. PLACOID FISHES. Hybodontidte. HYBODUS, . 24 10 9 1 Oolite. Wealden. 1 332 MIDDLE MESOZOIC STBATA. No. of Species. Lias. L. Oolite. Sphenonchus, 3 1 1 Ceslraciontidce. ACRODUS, 8 5 2 ASTERACANTHUS, - . 8 1 3 CERATODUS, 1 ... 1 Leptacanthus, 3 1 2 Nemacanthus, 1 ... 1 STROPHODUS, 6 ... 4 Lamnidce. OXYRHINA, 1 ... ... THYELLINA, 1 1 ... Eaiidce. ARTHROPTERUS, 1 1 ... CYCLARTHRUS, . 1 1 ... MYRIACANTHUS, 3 3 ... SQUALORAIA, 1 1 ... Edaphodontidce. GANODUS, . . 10 ... 10 ISCHYODUS, 3 1 ... M. Oolite. U. Oolite. Wealden. 1 GANOID FISHES. Sauroidce. ASPIDORHYNCHUS, 3 1 BELENOSTOMUS, . 3 2 1 CATURUS, . 3 1 1 CENTROLEPIS, 1 CONODUS, . . 1 COSMOLEPIS, , 1 EUGNATHUS, 1 13 LEPTOLEPIS, . 5 MACROSEMIUS, . . 1 OXYGNATHUS, . 1 OXYGONUS, ... . . PACHYCORMUS, . .' 10 10 PTYCHOLEPIS, . 3 3 SAUROPSIS, 1 1 THRISSONOTUS, . 1 1 Pycnodontidce. GYRODUS, . 5 2 GYRONCHUS, 1 1 MICRODON, 1 ... ... PYCNODUS, 14 1 12 SCAPHODUS, 1 1 SPILERODTJS, 1 ... TETRAGONOLEPIS, 1 1 Lepidoidece. ^ECHMODUS, . 12 11 AMBLYURUS, 1 1 DAPEDIUS, . 8 8 HISTIONOTUS, 1 ... ... LEPIDOTUS, 12 6 2 Nothosomus, 1 1 1 2 GENEEA OF OEGAKIC EEMAINS. 33? No. of Species. Lias. L. ( M OPHIOPSIS, 3 .. PHOLIDOPHORUS, 15 11 2 PLEUROPHOLIS, . 1 SEMIONOTUS, 1 1 Coilacanthidce. CTENOLEPIS, 1 1 REPTILIA. Dinosauria. CARDIODON, 1 1 HYI^EOSAURUS, . 1 ... IGUANODON, 1 ... MEGALOSAURUS, 1 1 REGNOSAURUS, . 1 , STENEOSAURUS, . 1 'i Crocodilia. CETIOSAURUS, 4 2 Crocodilus, . 1 .. GONIOPHOLIS, 1 .. M ACRORHYNCH US, 1 .. PELOROSAURUS, . 2 POIKILOPLEURON, 1 .. STREPTOSPONDYLUS, 4 1 2 SUCHOSAURUS, . 1 .. TELEOSAURUS, . 3 1 1 Lacertilia. Lacerta, 1 1 MACELLODUS, 1 .. NOTHETES, 1 Enaliosauria. ICHTHYOSAURUS, 10 9 .. PLESIOSAURUS, . . 12 9 PLIOSAURUS, 3 Chelonida. Chelone, 3 M Platemys, . 3 PLEUROSTERNON, 4 M Testudo, 1 1 TRETOSTERNON, . 1 > Trionyx, 1 1 Pterodactylida. PTERODACTYLUS, 3 1 1 MAMMALIA. AjVIPHITHERIUM, 2 2 PHASCOLOTHERIUM, 1 1 SPALACOTHERIUM, 1 .. STEREOGNATHUS, 1 1 L. Oolite. M. Oolite. U. Oolite. Wealden. 3 2 1 BIRDS. 334 MIDDLE MESOZOIC STKATA. LIAS FOSSILS. 196 197 193 Ophiura miller!. 194 Diadema seriale. 195 Rhynconella acuta. 196 Spirifer WalcottiL 197 Avicula cygnipes. LIAS FOSSILS. 335 200 199 203 198 Avicula inequivalvis. 199 Pccten lugdunensis. 200 Plagiostoma giganteum. 201 Plicatula spinosa. 202 Gryphea Incurva. Trigonia literata. MIDDLE MESOZOIC STEATA. 204 207 204 Corbula cardioides. 205 Modiola scalprum. 206 Cardium truncatum. 207 Ammonites crassus. LIAS FOSSILS. 33V 210 208 Ammonites Clevelandicus. 209 Ammonites. 210 Ammonites Bncklandi. 211 Ammonites Walcottii. 212 Belemnites pistiliformis. 213 Ink bag of a cephalopod. 338 MIDDLE MESOZOIC STBATA. 214 216 214 Ichthyosaurus communis. 215 Plesiosaurus dolichodeirus. 216 Pterodactylus longirostris (w, probable edge of the wing). LOWEE OOLITE FOSSILS. LOWER OOLITE FOSSILS. 339 219 21 7 Tseniopteris vittata. 218 Equisettun colimmare. 219 Pterophyllum comptum. 220 Bracliypliyllum mammillare. 340 MIDDLE MESOZOIC STEATA. 226 225 227 221 Apiocrinus rotundus. 223 Rhyncon. spinosa. 223 Terebratula digona. 222 Nucleolites clunicularis. 224 Terebratula globosa. 226 Perna quadrata (a, the hinge). 227 Gervillia lanceolata. LOWER OOLITE FOSSILS. 341 228 Ostrea Marshii. 229 Ostrea Sowerbii. 232 Pholadomya acuticosta. Gryphaea cymbi Pholadomya Mu urn. omya Murchisoni. 342 MIDDLE MESOZOIC STRATA. 233 Trigonia costata. 234 Isocardia concentrica. 235 Astarte minima. 236 Astarte elegans. 233 Ammonites striatulus. 237 Pleurotomaria conoidea. 238 Ammonites Brongniarti. LOWEE OOLITE FOSSILS. 343 240 240 Phascolotherium Bucklandi. MIDDLE OOLITE FOSSILS. 243 244 241 Cidaris coronata. 242 Cidaris florigemma. 243 Disaster ovalis. 244 Nucleolites dimidiatus. 344 MIDDLE MESOZOIC STBATA. 246 246 246 Clypeus semisulcatus. 246 Disaster bicordatus. 249 Gryphsea dilatata. 247 Serpula squamosa. 248 Pecten inaequisulcatus. MIDDLE OOLITE FOSSILS. 345 250 Trigonia clavellata. 252 Isocardia rhomboidalis. 254 Turbo muricatus. 251 Modiola bisulcata. 253 Nerinasa Goodhallii. 255 Ammonites calloviensis. 256 Belemnites sulcatus. 346 MIDDLE MESOZOIC STRATA. UPPER OOLITE FOSSILS. 257 257 Pecten lamellosus. 258 Ostrea dcltoidea. 200 Exogyra virgula. TJPPEE OOLITE FOSSILS. 347 264 261 Cast of Trigonia. 2G3 Thracia depressa. 262 Cardium dissimile (cast). 264 Terebra Portlandica (cast). 265 Nerita angulata (cast). MIDDLE MESOZOIC STRATA. WEALDEN FOSSILS. 266 Mantellia nidiformis. 268 C. Purbechensis (lower Purbeck). 267 Hemicidaris Purbechensis (middle Pur- 269 Cypridina fasciculata (middle Purbeck). beck). 270 Cypridina tuberculata (upper Purbeck). WEALDEN FOSSILS. 349 271 273 275 276 271 Cypridina Valdensis (Wealden). 274 Modiola Fittoni (Purbeck). 272 ArchaeoniscusBrodise (middle Purbeck). 275 Cyrena Media (Wealden). 273 Uno Valdensis. 276 Paludina fluviorum (Wealden). 277 Physa Bristovii (middle Purbeck). 350 TJPPEE MESOZOIC STEATA. CHAPTER XI. UPPEE MESOZOIC STEATA. Cretaceous System. mineral Character. That a peculiar type of mineralogical charac- ter belongs to each system of formations must have been sufficiently evident through the whole course of our investigation. The gneiss and mica slate system, the Cambrian and Silurian systems, the lime- stones of the carboniferous system, the coloured marls and magne- sian limestones of the Permian and saliferous systems, the oolites, are all resting points for the mind, and amidst a multitude of shades and gradations, strongly impress upon us the distinctive features of the several periods of time at which these so different rocks were in a predominant degree produced. Mineral characters alone, when rightly used, are in many instances sufficient to determine the geological relations of even distant re- gions ; and when conjoined with the evidence of organic remains, and controlled by careful survey of the strata above and below, they form a secure groundwork for topographical geology. The cretaceous system is equally definite as any of the others with respect to the distinctness of its prevailing mineral ingredients, and not less characteristically marked by peculiar marine exuviae. Chalk and green sands are terms understood by all the geologists of northern Europe ; and even on the southern side of the Alps their representatives may be recognized. Surface of Country. Through England the ranges of chalk hills form a geographical feature even more important than that of the oolites ; for though in general not so elevated, they are less inter- rupted and more extensive, more uniform in composition, and therefore more characteristic in aspect. The chalk hills form the first great ridge which is to be crossed from the eastern side of the island, and nothing can be more remarkable or instructive than such a journey. On approaching these broad hills from the level or gently undulated plains of the eastern counties, or the clay vales of the oolite system, the country changes entirely. The streams run in smoothly sloping valleys, the hills rise with beautiful swells into a long waving out- line, seldom broken by a tree, but often capped by an ancient tumu- lus. Arrived on the summit, we behold a mighty extent of broadly undulated land with abundance of depasturing cattle, but few habi- tations of men. Plants, eminently characteristic of calcareous soil, force themselves on the attention ; flints abound in the fields, chalk CEETACEOUS SYSTEM STJEFACE OE COUNTEY. 351 is cut through in the roads, the soil is thin, the herbage short, the surface dry, and we feel ourselves in a new physical region. This impression is confirmed when we observe more carefully the numerous undulations upon the surface of the "wolds ;" for all these may be traced into connection as so many ramifications of greater valleys, which themselves often unite, and pursue a considerable course without enclosing even the smallest rill, or showing even the mark of a watercourse. These dry valleys descend from their origin in regular slopes, and are clearly the work of water, operating with great force, and for some time, but in the present system of nature the watery agent has wholly disappeared. The rains are absorbed as fast as they fall upon this dry surface, and sink to considerable depths in the rock, where they are treasured up in reservoirs to supply the deep wells and the constant springs which issue at lower levels. In a word, broad, swelling hills, smooth, winding, often dry val- leys, and a bare, dry, grassy surface are the general features of the chalky districts. This character of surface belongs, as Dr. Lister remarked long ago, to the chalk wolds of Yorkshire, Lincolnshire, Norfolk, Suffolk, Berks, Wilts, Dorset, Hampshire, Surrey, Kent, and Sussex. Groups of the System. The cretaceous system forms conveniently two formations. Supposing the whole to be present in a single sec- tion, we should have the following general series : (f Upper chalk, with abundance of flints in layers and nodules. Chalk formation. < e Middle part (usually called lower) chalk, with fewer flints. (d Lower part (usually called chalk marl, or malm.) P, , ( c Upper green sand, malm rock, or firestone. i.nTG6n Scind 1 7 /-* ti_ t * < b Gault clay. (a Lower green sand or iron sand. d and c are sometimes undistinguishable. The lower green sand gene- rally forms a distinct ridge, which may even exceed the chalk in height. The complete system here presented occurs in many parts of Kent, Sussex, and Hampshire ; but generally in other parts of England the sections are modified, so as to present only partial assemblages of the beds, sometimes one, sometimes another being deficient ; and with respect to the malm rock, great differences are observable. Thus, in Wiltshire, where Smith took the type of this formation, we have the upper green sand remarkably developed ; the lower one and the gault are contracted. d Chalkmarl ........................................................... 100 c Green, gray, and yellow sand ...................................... 120 b Gault ................................................ - .................. 50 a Lower green sand .................................................... 30 352 UPPER MESOZOIC STRATA. Along the line of chalk hills from the valley of the Thames to Lynn, the upper green sand is almost lost in the chalk marl and gault ; green grains being mixed with the former, and still more in the upper layers of the latter. In Bedfordshire, the chalk marl pro- duces a bed of siliceous, chalky stone, which may probably be analo- gous to the firestone of Mesterham in Surrey, which is determined to belong to the upper green sand series. Indeed the sections along this part of the chalk range are very similar to those of Sussex and Kent. In Lincolnshire we meet with a new feature, a band of red chalk, at the base of the white rock ; under this no upper green sand, and generally no gault, but the red chalk rests upon a thick series of greenish and ferruginous sands, with included beds of sandy limestone, full of fossils resembling those of the lower green sand of Kent. This county has been very badly represented in most of our maps. In Yorkshire the cretaceous system consists of- Upper chalk. Lower chalk and traces of chalk and marl. Red band of chalk. Gault with green grains passing downwards into Kimmeridge clay, without the intervention of the lower green sand. From several researches abroad it has been thought that the chalk group of England and France is imperfect in the upper terms, and that the well-known Maestricht beds, and the more recently investi- gated Grosau beds, appear to soften the transition from the chalk to the true tertiary strata. We shall now briefly trace the history of these several members of the green sand and chalk groups, beginning as usual with the lowest. We are indebted to Dr. Fitton for a very laborious collection of the natural sections which many parts of England offer, to illustrate this series of strata. He has also tabulated the organic remains, and thus honourably connected his name with the " green sand." * The Lower Green Sand. (Syn. Iron Sand, Shanklin Sands, &c.) In Lincolnshire the lower green sand is a considerable mass of yel- low, often very irony sand, forming, toward the west, poor heaths upon the Kimmeridge clay, exactly like those about Lynn, Ampt- hill, and Grodstone. It contains a good deal of bad ochre, very simi- lar to that of Shotover Hill, and fines of oxide of iron like that of Eyegate. Beds of gray stone, blue within, flat-bedded, sandy, and full of fossils, lie in it, and afford excellent road materials. These are dug at Tealby, Market Stainton, Ludford, Cawkwell, Bluestone Heath, Stainton in the Hole, &c. It has considerable resemblance to the Kentish rag, and contains exogyra sinuosa, pecten cinctus, plagiostomata, serpulse, ammonites, alcyoniform bodies, small corals, and many other fossils ; but echini and belemnites appear unknown Geological Transactions, 2d series, vol. iv.. and GeoL Journal for 1847. THE LOWER GffiEEN SAND. 353 in it. From these details it is evident that the stratum has the most decided characters of lower green sand. It is exposed by denu- dations in the chalk, and also ranges on the west of the wolds for a great length by Rasen, Lessington, Linwood, &c., to Louth. The whole thickness is probably 100 feet. These notices are partly derived from personal observations in 1821, but principally from a special visit to the district in 1833 with two friends, Mr. W. H. Dikes and Mr. J. E. Lee, who have fully explored it. Mr. Lee made an excellent model of it. As usual in coloured sands, this stratum often contains veins of perfectly white sand. At Lynn this has been found of value for the glass-houses. In Cambridgeshire and through Huntingdonshire, the iron sand forms a narrow course of low hills ; but through Bedfordshire and Buckinghamshire it takes a commanding station, forming heathy ridges from Potton to Woburn, and through Buck- inghamshire and Oxfordshire, capping Brickhill and Brill Hills, Shotover Hill, Cumnor Hurst, and Faringdon Clump. In Wilt- shire, Spy Park, Bowood, Seend Hill, are capped by these beds ; but they are supposed to thin out to the south, and to be lost, until in Blackdown they are probably associated with the upper green sand. In the Isle of Purbeck and the Isle of Wight it is an important rock, and, as observed before, encircles the whole of the Wealden formation of Kent and Sussex. Through the whole of its range from Cambridgeshire into Wilt- shire it is a highly ferruginous sand, with spheroidal or merely irre- gular concretions of oxide of iron, frequently enclosing a coarse brown ochre. At Shotover, the fine yellow ochre forms two irregu- lar beds, separated \)j a thin parting of clay. Fuller's earth also occurs in it in layers in Bedfordshire, especially at Woburn. Grains of green sand abound in some layers of these beds in Bedfordshire and Buckinghamshire, and constitute it a real green sand. Chert layers also are formed in it, and many of the beds assume the aspect of coarse conglomerate, used by the ancient Britons for the making of quern stones or carstones, whence Smith gave this name as a synonym of the iron sand. Fossil wood is frequent in these beds. In Bedfordshire its thickness may be stated at 100 feet ; in Wilt- shire Lonsdale finds it 30. In the Isle of Purbeck, the iron sand consists of many beds of quartzose conglomerate, and of coarse and fine grained sandstones, containing beds of wood coal. In the Isle of Wight, dark red ferru- ginous sandstones in the upper part, and alternations of red and yel- low ferruginous sands and clays in the lower part, form the substance of all the southern half of the island, and contribute much to the beauty of the scenery of the Undercliff. In its long course around the Wealds of Kent and Sussex, the 2A 354 UPPEE MESOZOIC STEATA. lower green sand presents, with the general characters noticed above, some local peculiarities of interest. In Leith Hill, its extended pla- teau makes a commanding feature, and shows a great thickness of brown sands, with abundance of chert, with confluent grains passing into chalcedony, and some alcyonites like those of the Isle of Wight, The importance of the lower green sand as a geographical feature diminishes as it proceeds round the south side of the Weald, but the northern range is generally elevated and remarkably continuous by Ryegate, Nutfield, and Maidstone to Hythe and Folkstone. At Byegate it is almost exactly like the ferruginous rock of Woburn ; at Nutfield it produces beds of Fuller's earth ; from Maidstone to Hythe and Folkstone the sands are in general remarkably, and even excessively rich in green grains and nodules, and contain beds of whitish limestone, sometimes chalky and often cherty, with green grains, considerably rich in ammonites, trochi, cardia, pectens, lutra- rise, exogyra, echinites, and other fossils. These beds may be gene- rally called Kentish rag. Some of them are of a dark gray colour, very hard, full of green grains, and rich in many fossils, some of which are usually found in the upper green sand. The cherty beds of Leith Hill and Haslemere are probably the representatives of these calcareo-siliceous layers. Some of the beds of lower green sand about Folkstone are exces- sively coarse in the grain, and absolutely crammed with green grains and nodules. The large species of exogyra is very frequent, and appears characteristic. The blue marl or gault rests immediately on the sandy beds. Dr. Fitton presents the following detailed sections of the lower green sand at Atherfield, Isle of Wight, where, and between this place and Blackgang, the whole series is seen from the Wealden for- mation below to the gault above.* The thickness here is 808 feet ; at Hythe, near Folkstone, according to Mr. Simms, 406J feet. Ft In. 49 to 55 Various clays and sands 118 4 46 to 48 Upper clays and sand rock 118 45 Ferruginous bands of Blackgang above 20 6 41 to 44 Sands of Walpen, under cliff 97 40 Foliated clay and sand 25 38,39 Cliff-end sands 19 3 36,37 Second Gryphsea beds 16 35 Walpen and Ladder sands 42 26 to 34 Upper Crioceras group 46 2 24,25 Walpen clay and sands 57 17 to 23 Lower Crioceras group 16 3 14 to 16 Scaphites group 50 4 11 to 13 Lower Gryphsea beds 32 4 to 10 The 'Crackers' 85 3 Atherfield clay 60 1,2 Pernabeds 5 3 * Geological Journal, 1847. ATHERFIELD SECTION. 355 In the 55 groups thus placed the distribution of 155 species of fossils is carefully traced. The general result is as under : No. of fossils. No. of groups. 55 54 to 50 49 , 48 47 , 46 45 b .. 44 43 42 41 40 39 38 37 36 35 ? 01 r No. of groups. No. t 34 b ffoss 9 ] Is. No. of groups. 16 No. of fossils 7) 33 13 15 . , 7 L 32 3 14 ::::::: 4> 31 2 13 19^ 30 L 12 si 29 3 11 4J 28 10 12^1 27 3 9 27 26 9 8 . . . 19 25 in 7 .. 27 24 *> 1 6 5 23 r f... 2 22 o 10 21 <> 5 | 1 20 11 1 43 19 6 . . 13 18 8 4 32 17 10 3 . 23 2 .. 53) 1 ., ..46} The relative abundance of life in the lower part of this great series of sands and clays is remarkable. If we range the sixteen larger groups in succession, and count the species in the several beds (in- cluding repetitions"), we have the following result : No. of distinct No. of species Repetitions in fossil species in Larger groups. including repetitions. each group. each large group. 16 2 35 4 1 6 4 6 5 13 2 10 76 11 80 The total number of species in these groups (excluding all repe- titions) is 155. The occurrences being 254, we have repetitions between group and group 99 out of 155 ; and, there being 16 groups, the average 99 value of the fraction of distributiveness * -,^ Kxyng - loo X lb * See Palaeozoic Fossils of Devon, and Memoirs of Geological Survey, vol. ii., for example of this and other calculations. 15 1 1 14 . 46 11 13 12 8 12 ... 11 5 4 10 .. . . 15 ... 9 9 18 14 8 28 23 7 16 11 6 39 24 5 18 ... 16 4 , 26 , 16 3 , 191 115 2 23 , 12 1 .. , 99 .. 19 .. 356 TTPPEB MESOZOIC STEATA. Nearly all the species make their first appearance in one or other of the six lower groups (1 to 23 smaller groups). In the 14th great group 31 of the species are disappearing. The C*ault or Oolt. (Syn. Blue Marl of Tetsworth and Folkslonc, micaceous Brick-earth, Smith.) The gault or golt is an argillaceous member of the green sand group, of great interest to the concholo- gist ; since in Kent, Surrey, Sussex, Wiltshire, Cambridgeshire, and Yorkshire it yields a most rich supply of molluscous remains, many of them minute and of the greatest beauty. It accompanies the lower green sand around the whole district of the Weald, separates the upper and lower green sand in the Isles of Wight and Purbeck, and follows with the same relations the range of the green iron sand through Wilts and Berks, Buckinghamshire and Bedfordshire, and Cambridgeshire ; and appears in Yorkshire without either upper or lower green sands immediately below the chalk. Its average thick- ness may be fairly estimated at 100 feet, and it universally forms a characteristic narrow valley under the chalk. No remarkable pecu- liarity of mineralogical aspect or chemical composition distinguishes the gault, except a general tendency to admit green grains into its more sandy portions. It produces a capital brick-earth, fit for white bricks, in the midland counties. It is often of a very dark blue, but sometimes of a light gray colour. Near Folkstone it contains in the lower part a remarkable layer of small, irregular, ironstone nodules, every one of which is formed round an ammonite. A similar layer contains similar ammonites at Steppingley Park, Bedfordshire. At Speeton in Yorkshire oval nodules of similar nature generally enclose small specimens of astacida?. Small belemnites, crioceratites, ammo- nites, nuculae, striated terebratulae, serpulas, &c., abound in this gault, and serve admirably to complete the catalogues of fossils of the cretaceous sj^stem. The Speeton clay is found immediately below the "red chalk," as that is covered by "white chalk." Neither upper nor lower green sand can be traced here. It does not appear distinctly divisible into two parts ; yet the lower part, towards the coralline oolite, yields some Kimmeridge clay fossils. The upper part affords crioceratites, nuculadse, and belemnites of the cretaceous group. The analogy of the upper part of this clay to the gault of Folkstone is admitted ; but we think it also allied to the gryphitic and crioceratitic groups of the lower green sand in Dr. Fit-ton's section. In the catalogue of genera which follows, the Speeton clay is classed with the gault. The Upper Green Sand. The upper green sand was first examined in Wiltshire, where it consists of green, gray, and irony sands, im- mediately subjacent to the chalk, and affording passages for the col- lected water of that thick deposit downward to the gault. The green grains there assumed to be characteristic of these strata are UPPER, GREEN SAND LOWER CHALK, ETC. 357 now known to occur in older sands (in calcareous grit, for instance), and in much more recent beds (as above the chalk frequently), yet still the greenness of the sands immediately below chalk is a curious general fact. They are, however, quite as often gray or even whitish, with a remarkable tendency in the grains to coalesce into meagre sandstone, sandy chert, and at length semi-transparent and chalce- donic chert. These effects are particularly to be observed among specimens of the sponges, and so called alcyonia, which abound in the green sand group. It is easy to understand how so variable a mass of sands placed immediately below the chalk, and clearly in many places (as at Havre) graduating into that calcareous rock, should in several instances become so cretaceous as to be hardly dis- tinguishable from the chalk itself. This happens in Bedfordshire, where the Tattenhoe stone appears to be the representative of the upper green sand, in Surrey at Merstham, in Dorsetshire at Beer. Hound the Weald of Surrey and Sussex, the malm rock, which is certainly coeval with the Wiltshire green sand (Murchison), and also with the Merstham firestone, occasionally shows many green grains, and at Beechy Head (Mantell) changes to nearly the ordi- nary type of the green sand of Wiltshire. From these considera- tions we are fully justified in regarding the upper green sand as intimately connected with the lower commonly argillaceous part of the chalk, just as the calcareous grit is with the coralline oolite, and the calciferous sand with the inferior oolite. In particular places, mechanical causes gave a predominance to its sandy character, and in others the abundance of organic exuvia3 impressed it with a parti- cular zoological type. This mode of viewing it exactly accords with its general character through France, where it is associated with the lower argillaceous chalk under the title of glauconie crayeuse. According to this classification, the upper green sand or firestone beds form a nearly continuous base for the chalk from Lynn to Dorsetshire, and round the whole of the Weald of Kent arid Sussex, yielding organic remains at intervals. The thickness of this mass of sand is quite irregular, from a few feet near Cambridge to some- thing about 100 feet in Blackdown. Lower Chalk, or Chalk Marl. Chalk marl may be viewed as the next step in the gradation of changes by which we are conducted from the green sand system to the true cretaceous type. It is, in fact, an argillaceous chalk, holding variable quantities of clay and sand, superimposed upon the green sand or malm rock, and gradually changing upwards to the lower chalk. It is, perhaps, observable on the western slopes of the Yorkshire wolds above the red chalk, but is distinctly traceable below nearly the whole range of the chalk hills from Lynn to Dorsetshire, and round the whole of the Weald, everywhere closely associated with, and indeed hardly separable from, 358 UPPER MESOZOIC STRATA. the malm rock or firestone, and often enclosing, as near Woburn and Folkstone, green grains and fossils of the true upper green sand. Middle (or Lower) Chalk. In England, generally, the lower half of the thick mass of chalk is harder, more jointed, and less divided by layers of flint nodules than the upper part. It is often of a grayer colour, and, to a certain extent, distinguishable by a different suite of organic remains. In particular, it appears to contain very few of the asteroidea, crinoidea, or echinoidea, not so many belem- nites or terebratulse, but, on the contrary, yields more ammonites, some hamites, trochites, and other fossils approaching to those of the green sand group below. But the mineralogical character of the lower part of the chalk is liable to great variations. In York- shire, three-fourths of the whole mass are hard, and the lower por- tions are as much traversed by layers of flint nodules, at pretty regular distances, as the upper parts. In the Dover cliffs, beds of soft cretaceous marl divide the chalk without flints into two portions, the upper one yellowish, hard, and containing numerous thin beds of organic remains, the lower one whiter, softer, often gritty at the top, enclosing masses of pyrites, but few organic remains. (W. Phil- lips, in Geology of England and Wales) The Upper Chalk. The upper chalk is usually recognized in Eng- land by its whiteness, softness, numerous layers of flints at intervals of four to six feet, and abundance of zoophytic remains. Sponges of many kinds, small lamelliferous corals, millepores, crinoidea, asteroi- dea, echinoidea of very remarkable form, large inocerami, belemnites, and abundance of terebratula3 are the most frequent of its numerous fossils. The layers of flint nodules are exceedingly interesting, and throw light upon the mode of formation of the chalk. They are always found in the planes of stratification, generally irregular in figure, black or gray within, with traces of spongiferous bodies, shells, echini, or other organic bodies. The external crust is usually white and siliceous. The sponges also are often quite white and siliceous, and lodged in a cavity, left by the decay of part of their substance. The crusts of echini are usually, even when enveloped in flint, converted to calcareous spar, and belemnites retain their original radiated structure. Occasionally, as at Sudbury, the flint occurs in thin layers parallel to the stratification. It seems probable that in the formation of the chalk from the decomposition of the sea water then holding lime and silica in solu- tion, the carbonate of lime and silica fell to the bottom together, in quantities sufficient on each occasion to constitute a bed of chalk and flint, and that the latter substance was especially attracted by the organic remains then lying on or beneath the beds, so as to col- lect round the sponges, echini, &c., exactly as the oolitic matter has been collected round shells, the lias limestone round ammonites, the CEETACEOTJS SYSTEM IBELAKD. 359 carbonate of iron round ferns, &c. Analogous cases occur in the spongiferous cherts of the Portland oolite and coralline oolite ; and we might perhaps venture to extend the same mode of reasoning to the case of chert nodules in carboniferous limestone, for these often (not so generally as in the case of flint) contain organic remains. Pyrites is generally plentiful in the upper chalk, variously crystal- lized, and is not unfrequently associated with silica in the sponges which lie in chalk. It is in these cases generally decomposed near the surface into brown oxide of iron. Flints are very often split or cracked in their native repositories, as if by contraction of the mass ; and this sometimes, but less fre- quently, happens, when organic remains of a solid kind are enclosed in them. The most remarkable cases of this nature are described by Mr. Webster, in the dislocated upper strata of chalk in the Isle of Wight. All the flints in the layers which alternate with chalk are found broken in every direction into pieces of every size, which re- main in their relative places enclosed within the cell of chalk, and showing no other signs of fracture than a fine line, as in shivered glass. On being removed from their place, the flints fall into many pieces. This singular fact seems connected with the disturbances of the chalk, and may, perhaps, be due to the violence of the tremor then impressed upon the mass, a tremor which might shiver elastic flint (especially if, like, a Rupert's drop, its particles had been pre- viously in a state of tension), but leave the chalk unaffected. The thickness of the chalk in England is seldom less than 500 feet, and rarely so much as 1,000 feet. In the Isle of Wight, how- ever, the section at Culver cliff seems to give as much as 1,200 feet. It has been estimated indeed by Mr. Greenough at 1,300 feet. The ammonites, turrilites, scaphites, crioceratites, &c., which abound in the lower parts, scarcely reach the upper part ; while belemnites mucronatus, and ananchytes ovata, scarcely appear in the middle and lower groups. Range of the Cretaceous System out of England. The principal range of the cretaceous rocks is included within the general boundaries of the European basin, and it is probably not at all less extensive than the oolitic system, though by the diffusion of tertiary rocks above it, its course in large tracts of country is wholly subterranean. Ireland. The cretaceous system of Ireland is in a depression, on the western side of what is usually understood by the basin of Europe. It consists of chalk 200 or 300 feet thick, harder than is common in England, but with a similar though less extensive suite of organic remains, and rests on green sand, there called mulatto, with the usual characters of that group in England. Lias is found 360 TTPPEE MESOZOIC STRATA. beneath at the Giant's Causeway. In Scotland, only a dubious indi- cation of the former extent of the cretaceous system is afforded by the flints which rest upon primary rocks near Peterhead. Within the natural modern boundaries of the principal basin of European secondary strata the primary rocks of Scotland, Cumber- land, Wales, Cornwall, and Brittany, on the west ; the Pyrenees, the Alps, and the Carpathians, on the south ; Caucasus and Oural on the east ; Finland and Scandinavia on the north the cretaceous system, chalky, marly, or sandy, is very largely developed. The type of the formation may be taken in Southern England or Northern France indifferently. In the latter country its extent on the surface is pro- bably equal to the whole superficial area which it occupies elsewhere in Europe. It encircles with a broad belt the basin of Paris, and passes off on the north-eastern side into Belgium, which whole coun- try it probably underlies, though the tertiary deposits conceal it, except along the sides of the Meuse. At Maestricht the upper beds of the cretaceous formation have, in many respects, mineralogical and organic, a remarkable analogy to the calcaire grossier, which is the lowest really marine tertiary rock in the vicinity. These beds, however, by their principal character really belong to the cretaceous system, of which they may be considered the highest terms at pre- sent known. A little appearance of the chalk is observable north of the coal of Elberfeld, to which it is unconformed, as well as to that of Namur and Liege. The chalk system most probably underlies the whole region of Northern Germany, from the point last men- tioned north of the oolite and lias of Westphalia. The green sand is remarkably well exhibited with characteristic fossils in the roman- tic tract of Saxony, north of the Erzegebirge (there called quader- sandstein), as well as an upper calcareous portion supposed equiva- lent to the chalk and called planerkalk. North of the Carpathians both chalk and green sand occur in long ranges of hills, passing from Poland by Lemberg into Podolia and the south of Russia. It reaches the Dniester, and extends to the plains of Volhynia. It forms con- siderable eminences around Grodno in Lithuania. " Farther south, in the plains of Moldavia, Podolia, and Bessarabia, it appears only in detached portions. Chalk is found on the southern side of the gra- nitic steppe in the Crimea, and on the borders of the Sea of Azof, between the Berda and the Don. In the country of the Don Cos- sacks, in the governments of Woronack, Koursk, and Toula, it appears in hills and on the banks of rivers, and probably constitutes the base of that great and fertile plain." (Pusch, quoted by De'la Beche, Manual of Geology.) In Pomerania and Mecklenburg, and the Island of Rugen, cliffs of chalk occur with the usual fossils of England, and in Sweden it rests upon rocks of gneiss and greywacke, and only in one instance, at CEETA.CEOUS SYSTEM FOREIGN LOCALITIES. 361 Limhamm in Scania, upon rocks of the oolitic era. In the north of Germany it appears at intervals, near Lurieburg, and on the borders of the Harz mountains (at Quedlinburg) ; and there seems no reason to doubt that the whole vast plain of Northern Germany, from the Rhine to the Vistula, rests upon the cretaceous system. What re- mains of the Island of Heligoland consists of green sand. The whole line of the Alps from the Saleve to Vienna is bordered upon the northern side by rocks of the cretaceous system, which are closely associated in character both with the oolites beneath and with the tertiaries which lie above. A similar observation applies to the south side of these mountains. Rocks of this era range down the Apennines, and occur abundantly in the Maritime Alps, there, as well as about Geneva, intimately associated with the upper oolitic beds. Deposits of this age also lie in old valleys of the Jura moun- tains, which range in a north-eastern and south-western direction. The Pyrenees are bordered on both sides by green sand and sandy and calcareous beds, containing with many chalk fossils some of ter- tiary types. Over this extensive area the mineralogical characters of the system are tolerably uniform, except in the vicinity of the Alps, where the violent disturbances to which that mountain range has been subjected appear to have entirely altered the aspect of these beds, so as to per- mit authors to speak of black chalk, which, however, is really a portion of the green sand group. Over all the region already men- tioned in France, in Belgium, at all the points in Northern Ger- many, in Poland, in Russia, Pomerania, Denmark, and Sweden, the chalk has its usual characters and appearance, and contains anan- chytes and spatangi, belemnites, terebratulsB, inocerami, &c. The green sand in France, near Aix-la-Chapelle, along the Erzgebirge, in Poland, along the Carpathians, in Heligoland, has its usual cha- racters. Indeed, even along the Eastern Alps, but especially in the Swiss and Savoy Alps, and the Jura, the green sand group retains nearly its usual aspect, and exhibits its usual fossils ; and an English geologist placed at the Perte du Rhone, or amidst the relics of the Montagne de Fiz, is at once introduced to the geology of the vici- nity. Green sand layers alternate with the upper part of the Jura oolites in the Saleve, and the same phenomenon appears to happen along the Eastern Alps (Murchison's and Sedgwick's Memoirs, Geo- logical Transactions), where some parts of this group contain fuci so as to be characterized thereby. In the Maritime Alps the lower beds of the cretaceous formation consist of light coloured limestone charged with green grains, and full of belemnites, ammonites, nau- tili, and pectines, and appear intimately connected with the top of the Jura limestone deposit.* * De la Beche, Manual, 259. 362 TJPPEE MESOZOIC STEATA. On the southern side of the Alps the beds of the cretaceous era, which descend to the plains of Lombardy, are principally composed of white, greenish, and reddish beds, and it appears that a gradation of character may be traced through the oolitic, cretaceous, and ter- tiary strata here uplifted. (Murchison.) Some of the light coloured limestones referred to the chalk are called scaglia, and the mountain of the Yoirons near Geneva yields a rock of similar nature. Dislocations of the Cretaceous System. Like the oolitic era, the cretaceous period appears to have been one of regular action, perhaps still more uniform than that, but not of so long duration. For we do not find its deposits to contain so many distinct suites of organic remains, nor so many remarkable repetitions of analogous rocks as occur in the oolitic system. The lower sandy beds of the system, indeed, may be thought to have been influenced by the convulsions which upheaved the oolites, but we cannot assent to the notion that the whole cretaceous system is derived from the mechanical movements thus impressed upon the waters. The organic remains of the system sufficiently disprove this, and the great extent and uniformity of the deposit of chalk is no otherwise to be explained than by general laws applicable to all the older and more recent calcareous strata. That disturbances of great extent happened somewhere after the deposit of the chalk in England, is evident from the extraordinary abundance of sandy and gravelly accumulations, sometimes resting in hollows of the chalk, which immediately cover that stratum. A great part of the plastic clay group is of this fragmentary and tumul- tuary origin, and its black flint pebbles are only water-worn chalk flints. But England does not appear to have been the centre of these convulsions, nor to have been much moved by them unless bodily, and without local and violent fracture of strata. It is, indeed, very probable, that parts of the chalk formation, originally deposited in deeper seas, were at this time brought up and made to constitute a shore and to be liable to all the waste of the waves. And some portions might be, and probably were, raised to dry land, and exposed to the weather and the wearing of streams. But we can seldom at present undertake to say where such a shore occurred, or in what part exactly the chalk was raised into hills. In Ireland, at this period, great eruptions of basalt happened, and broad lakes of lava covered the chalk of that country. In France the chalk was wasted as in England, and its flints rolled to pebbles, to constitute the pebbly beds of the plastic clay group ; and this seems to have been chiefly effected by fresh water streams, for we find in the plastic clay of France few organic remains besides DISLOCATIONS OF THE CEETACEOTJS SYSTEM. 363 terrestrial and fresh, water productions. Yet here, we believe, it is equally difficult to say what portions of the chalk were thus raised and exposed. The surface of the chalk in France appears to have been even more wasted, furrowed, and pitted than in England. To this period Elie de Beaumont ascribes the dislocations which in the French Alps and the south-western extremity of the Jura, from the environs of Antibes to those of Pont d'Ain and Lons le Saulnier, present a series of dislocations in a direction north north- west. The primary mass of Mont Viso is traversed by this system of faults. The eastern crests of the Devolny, on the north of Gap, are formed of the oldest beds of the green sand and chalk, thrown up in the direction north north-west, and raised more than 4,700 English feet above the sea, while at their feet, and 2,000 feet lower, the upper portion of the cretaceous system remains horizontal and entirely undisturbed. Everything belonging to this particular epoch, that is calculated to throw light on the changes then operated on the external features of the globe is of the highest curiosity and importance, since the probability is great that very violent and extensive convulsions, pro- ducing most remarkable alterations in physical geography and in other conditions of organic life, must have happened to occasion so entire and rapid a change of plants, shells, and vertebrated animals, as, notwithstanding recent discoveries of supposed intermediate strata, is admitted to have taken place after the deposition of the cretaceous system. Some time after the above remarks were written, the third volume of the Principles of Geology (1st edit.) appeared, in which the able author ventured to do what we then thought too difficult to attempt, and define in one instance what part of the ancient bed of the sea was raised at the commencement and during the continuance of the tertiary period. Combining his own observations on tertiary strata with Mantell's discoveries, he proposed the theory that the elevation of the Wealden district of Sussex and Kent was contem- poraneous with, or only immediately antecedent to, the deposition of the tertiaries in those parts of the sea which are now become the basins of London and Hampshire ; that the elevation of the second- ary, as well as the deposition of the tertiary rocks, was produced by long continued operations of the same kind ; and that as different strata were raised in the Weald, to be wasted away by the sea and atmospheric action, the tertiary deposits, thence carried to the depths of the sea, were proportionately varied. We cannot now discuss this ingenious theory, because it is connected with a very extensive argument, involving many of the fundamental views of this author, Elie de Beaumont, and Von Buch, but the subject will be examined in its proper place. 364 UPPEB, MESOZOIC STEATA. ORGANIC REMAINS OF THE UPPER MESOZOIC STRATA. PLANTS. Confervites, Chondritcs, ALG^E. No. of Species. L. Green. Gault. U. Green. L. Chalk. U. Chalk. 3 3 2 2 Lonchopteris, Dracaena, . FILICIN^E. 1 1 LILIACE^E. Zamiostrobus, Clathraria, . Abietites, . Strobilites, . CYCADE^E. 1 CONIFERS. 2 1 1 AMORPHOZOA. Achilleum, Brachiolites, Cephalites, . Chenendopora, Choanites, . Cliona, Cnemidium, Coeloptychiutn, Conis, Coscinopora, Guettardia, Hippalimus, lerea, Manon, Paramoudra, Plocoscyphia, Polypothecia, Scyphia, Siphonia, Spongia, Talpina, Udotea, 1 10 12 7 1 3 2 1 1 5 1 2 4 6 1 3 5 10 8 11 GEtfEEA OF OBGAOTC EEMAINS. 365 No. of Species. L. Green. Gaul Ventriculites, . .13 ... Verticillites, . . 2 Xanthidium? . . 14 ... FORAMINIFERA. Bulimina, . 8 1 Cristellaria, 6 3 Dentalina, . 13 3 Flabellina, . 8 ... Frondicularia, 7 3 Gaudryina, . 3 2 Globigerina, 3 ... Guttulina, . 1 ... Lingulina, . 1 ... Lituola, 1 ... Margin ularia, 6 1 Nodosaria, . 7 2 Orbitolina, . 2 Flanulina, . 1 ... Pyrulina, 1 ... Quinqueloculina, . 1 1 Eosalina, 8 2 Rotalina, 11 3 Sagrena, 1 ... Spirillina, . 2 Spirolina, 2 1 Textularia, 10 1 Truncatulina, 1 ... Vaginulina, 3 2 Verneuillina, 2 1 Webbina, . . 1 ... ZOOPHYTA. Axogaster, . . 1 ... Bathycyathus, 1 1 Coelosmilia, 1 Cyathina, . 1 1 Diblasus, 1 .. Epiphaxum, 1 .. Holocystis, . 1 1 Micrabacia, 1 ... Parasmilia, 6 ... Parastraea, . 1 Peplosmilia, 1 ... Siphodictyum, 1 1 Smilotrochus, 1 ... Spinopora, . 1 Stephanophyllia, . 3 ... Synhelia, . 1 ... Trochocyathus, . 4 4 Trochosmilia, 2 1 Gault. U. Green. L. Chalk. U. Chalk. 13 1 ... 1 14 1 1 1 8 3 1 1 6 3 1 12 "3 ... 2 ..'. 2 ... I 1 2 1 ... ... ... ... 1 1 1 5 2 1 7 2 ... ... ... 1 ... 1 1 1 2 1 8 3 1 11 ... 1 2 1 ... 1 1 1 ... 1 10 ... 1 1 2 ... 3 1 1 2 ... ... 1 366 UPPER MESOZOIC STRATA. ECHINODERMATA. Ananchytes, Caratomus, Cardiaster, . Catopygus, . Cidaris, Cyphosoma, Diadema, . Discoidea, . Echinopsis, . Echinus, Galerites, . Goniopygus, Hemiaster, . Hemipneustes, Holaster, Micraster, . Nucleolites, Pygurus, . Pyrina, Salenia, Arthraster, , Goniaster, . Oreaster, ECHINOIDEA. No. of Species. L. Green. Gault. U. Green. L. Chalk. U. Chalk. . 1 ... ... ... ... 1 ' m 1 ... 1 ... ... 9 "l "l 3 ... 5 . 1 ... 1 1 ... . 12 2 1 1 8 7 ... ... ... 7 , 16 3 10 5 ... , 5 1 2 3 2 , 1 ... ... ... 1 m 3 1 2 , 6 ... 1 2 *4 , 1 ... ... 1 ... . 5 3 1 1 ... , 2 1 1 ... ... < 5 ... 1 4 1 . 4 ... ... 2 3 5 2 3 1 ... ... I ... , 2 ... ... ... 2 12 1 5 6 1 ASTEROIDEA. 1 ... ... ... 1 17 ... "2 "5 11 , 7 ... ... 1 6 Ophiura, OPHIURIDEA. Bourguetocrinus, Glenotremites, Marsupites, Pentacrinus, CRINOIDEA. 1 1 Serpula, Vermicularia, Vermilia, . 24 5 4 ANNELIDA. 1 2 Loricula, Pollicipes, Scalpellum, Verruca, 1 9 10 1 CIRRIPEDA. GEKEEA OF OEGANIO EEMAINS. 367 CRUSTACEA. ENTOMOSTRACA. No. of Species. L. Green. Gault. U. Green. L. Chalk. U. Chalk. Bairdia, . 6 1 2 2 1 4 Cythere, 4 1 1 1 2 3 Cythereis, . 8 2 6 2 7 Cytherella, 6 ... 3 ... 3 5 Cytheridea, 1 ... 1 1 1 1 Enoploclytia, 4 Etyus, 1 Grapsus, 1 Holoparia, . 1 Mesostylus, 1 Meyeria, 3 Notocorystes, 4 Pagurus, 1 Palinurus, . 1 Platypodia, 1 Podopilumnus, 1 Actinopora, Alecto, Atagma, Cellepora, Ceriocava, . Ceriopora, . Clypeina, . Cricopora, . Desmeopora, Diastopora, Discopora, . Domopora, . Entalophora, Eschara, Escharina, . Flustra, Heteropora, Hippothoa, Holostoma, Homoeosolen, Hornera, Idmonea, Lunulites, . Marginaria, Multicrescis, Petalopora, Proboscina, Pustulopora, MALACOSTRACA. BRYOZOA. 1 i ... ... 1 3 i .. ... 1 1 ... ... ... ,, 1 i i 4 ... 2 I .. 2 * 2 i i 1 . 1 2 ... 1 4 5 . ... 2 5 ;; ;;; ... 4 ... 2 ... 4 1 2 , ... 1 ... 1 , 1 ... 1 t 5 ... 1 1 i 2 2 .. >4 1 3 368 UPPER MESOZOIC STRATA. Kadiopora, . Reptocea, . Reptomulticava, Reptotubigera, Retepora, Siphoniotyphlus, Vincularia, . Zonopora, . No. of Species. L. Green. Gt 1 1 3 2 2 P? . 1 1 1 lult. U. Green. 1 1 3 2 1 L. Chalk. U. Chalk. BRACHIOPODA. Argiope, . Crania, Discina, Lingula, Magas, Rhynconella, Terebratella, Terebratula, Terebratulina, Tkecidiuin, . 2 4 1 2 1 19 7 28 2 1 MONOMYARIA. Anomia, 4 4 ... ... Avicula, 7 4 ... 3 ... ... Exogyra, . 9 3 4 4 2 4 Gervillia, . 5 4 1 1 1 ... Gryphjea, 1 ... ... 1 1 Inoceramus, 21 1 2 5 10 7 Lima, 26 7 2 11 8 2 Ostrea, 17 3 1 5 3 11 Pecten, 28 7 1 12 9 8 Perna, 4 2 1 1 ... ... Pinna, 8 2 1 3 ... 2 Spondvlus, . 8 1 ... 2 2 4 Vulsella, . 1 ... ... ... ... 1 DIMYARIA. Amphidesma, Anatina, Area, . Astarte, Cardita, Cardium, Corbis, Corbula, Crassatella, Cryptodon, 1 2 ... 1 8 4 ... 11 4 1 3 2 1 14 10 ... 1 1 ... 4 1 1 1 1 1 1 GENEBA OF OBGANIC BEMAINS. 369 No. of Species. L. Green. Gault. U. Green. L. Chalk. U. Chalk. Cucullaea, . 6 2 1 4 Cypricardia, 1 1 ... ... Cyprina, 5 1 ... 5 Cytherea, . 6 1 1 5 Diceras, 1 ... ... 1 Gastrochaena, 2 1 1 ... Isocardia, 3 2 1 ... ... Leda, .-, . 4 2 ... 1 . 1 Lithodomus, 2 2 ... ... ... Lucina, 6 3 1 2 Lutraria, 2 ... ... 1 1 Mactra, 1 ... 1 Modiola, 7 "5 ... 1 1 Mya, . . 2 ... 1 1 Myacites, . 8 6 1 2 Mytilus, 6 1 1 4 Neaera, 1 ... 1 ... Nucula, 11 4 5 4 Opis, . .. 1 ... ... 1 Pachyma, . 1 ... ... 1 Pectunculus, 2 ... 1 2 Petricola, . 2 ... 2 Pholadomya, 5 3 ... 1 1 Pholas, 2 1 1 ... Psammobia, 1 ... ... 1 Radiolites, . 2 ... ... 1 1 Solecurtus, . 1 1 Sphasra, 4 1 ... ... Tellina, 4 2 2 Teredo, 2 ... ... 1 Thetis, 4 i ... 3 Thracia, 2 i 1 Trigonia, 15 6 ... 11 Venus, 10 6 1 3 GASTEROPODA. Actaeon, Avellana, Cassidaria ? Cerithium, . Delphinula, Dentalium, Dolium? . Emarginula, Eulima, Fusus, Hipponyx, . Littorina, . Murex, Nassa, Katica, Nerinaea, Fhasianella, 5 2 2 1 6 ... 3 1 1 1 ... ... 1 7 6 1 ... ... 1 1 ... ... 6 1 3 3 "i 1 ... ... ... i 3 1 ... ... 2 2 1 ... ... 1 4 ... ... 4 ... 1 ... ... 7 2 7 1 ... 1 1 ... 1 ... ... 1 8 2 3 4 ... 1 ... ... 1 4 ... ... 4 ... 2B 370 UPPER HESOZOIC STRATA. Pleurotomaria, Pterocera, . Pterodonta, Pyrula, . Rostellaria, Solarium, . Trochus, . Turbo, Turritella, . Tylostoma, Bellerophina, No. of Species. L. Green. Gault. U. Green. L. Chalk. U. Chalk. Ill 1 1 2 6 2 1 4 3 ... 1 ... 3 ... 1 9 2 6 7 2 3 3 2 ... 6 2 1 5 1 1 1 ... 1 1 CEPHALOPODA. Ammonites, Ancyloceras, Baculites, . Belemnitella, Belemnites, Crioceras, . Hamites, Helicoceras, Nautilus, Ptychoceras, Scaphites, . Turrilites, . 71 7 29 20 24 3 8 4 4 ... 3 ... 1 2 4 ... 2 3 5 ... 5 ... 2 ... 3 1 2 ... ... ... 15 1 11 2 4 ... 1 ... 1 ... ... ... 17 7 1 3 11 1 1 ... 1 ... ... 2 ... ... 1 2 11 ... 4 ... 7 ... Hybodus, PISCES. PLACOIDEI. HYBODONTID^E. 3 1 CESTRAC1ONTID.E. Acrodus, Aulodus, Cestracion, Plethodus, Ptychodus, Strophodus, 1 1 2 16 2 LAMNUXE. Lamna, Odontaspis, Oxyrhina, Scylliodus, Corax, NICTIT ANTES. In Ireland. GENERA OF ORGANIC REMAINS. 371 EDAPHODONTID^E. No. of Species. L. Green. Gault U. Green. L. Chalk. U. Chalk. Edaphodon, 3 ... ... 1 2 Ischyodon, . 2 ... 1 1 NOTANUXE. Notidanus, . 2 2 SQUALID^. Orodus, . i . .2 2 GANOIDEI. SAUROIDEI. Lophiostomus, 1 1 Belonostomus, 2 2 Caturus, 1 1 Pomognathus, 1 i PYCNODONTIIXE. Pycnodus, . 4 1 3 Acrotemnus, 1 1 Gyrodus, 5 ... 1 4 Microdon, 2 2 Phacodus, . 2 2 LEPIDODEI. Lepidotus, . 1 1 COILACANTHI. Macropoma, 3 ... ... 1 2 PLECTOGNATHI. Dercetis, 1 1 G YMNODON TIME . Orthagoriscus, 1 1 CYCL01DEI. SALMONID.E, Acrognathus, 1 1 SCOPELIDJE. Osmeroides, 4 4 Tomognathus, 2 2 372 UPPER MESOZOIC STRATA. SCOMBERID.E. No. of Species. L. Green. Gault. U. Green. L. Chalk. U. Chalk. Coelorhynchus, . 1 1 Enchodus, . .... 1 1 Tetrapterus, 1 1 MUGILID.E. Calamopleurus, . 1 1 SPHYRENID^:. Cladocyclus, 1 1 Hypsodon, . 2 2 Saurodon, . 1 1 Pachyrhizodus, . 1 1 Saurocephalus, 2 2 CTENOIDEI. PERCID^E. Berycopsis, . 1 1 Beryx, 4 4 Stenostoma, 1 1 Homonotus, 1 1 REPTILIA. DINOSAURIA. Iguanodon, . 1 ... CROCODILIA. Polyptychodon, . 2 1 ... 1 1 1 LACERTILIA. Coniosaurus, 1 1 Dolichosaurus, 1 ... ... ... 1 ... Leiodon, 1 1 Mosasaurus, 1 1 Raphiosaurus, 2 ... ... ... 1 1 ENALIOSAURIA. Plesiosaurus, 4 1 ... 1 2 ... Ichthyosaurus, 1 ... 1 ... PTEROSAURIA. Pterodactylus, 4 ... ... ... 4 ... CHELONIDA. Chelone, 4 1 1 2 Protetnys, . 1 1 ... LOWER GEEEN SASD FOSSILS. 373 LOWER GREEN SAND FOSSILS. 281 278 Spatangus retusus. 279 Exogyra subplicata, 280 Lima elegans. 281 Requienia (Diceras) ammonia. 282 Crioceratites Duvallii. 283 Ancyloceras. 374 UPPER MESOZOIC STRATA. 285 286 284 1'tychoceras. 285 Hamites. 286 Trigonia caudata. 287 Exogyra sinuuta. GATJLT AND UPPEE GREEN SAND FOSSILS. 375 GAULT FOSSILS. 290 Inoceramus sulcatus. 289 Inoceramus concentricus. 290 Nucula pectin ata. UPPER GREEN SAND FOSSILS. 291 Pecten quinquesulcatus. 292 Plicatnla placunea. 293 Ostrea carinata, 294 Trigonia alajformis. 376 TJPPEE MESOZOIC STEATA. CHALK FOSSILS. 297 295 Spongia cribrosa. 297 Marsupites ornatus. 296 Apiocrinus ellipticus. 298 Ananchytes ovatus. 299 Spatangus coranguinum. CHALK FOSSILS. 377 301 302 304 SCO Terebratula Defrancii. 302 Exogyra coltimba. 304 Plagiostoma spinosum. 301 Rhynconella octoplicata. 303 Ostrea vesicularis. 305 Inoceramus Cuvierii. 306 Hippurites organisans. 378 UPPER MESOZOIC STEATA. 307 Spherulites ventricosa or Radiolites turbinata. 308 Hippurites bioculata. 310 Ammonites varians. 309 Ammonites monilis. 311 Ammonites rothomagcnsis. CHALK FOSSILS. 379 12 Belemnites rnucronatus. 314 Turrilites costatns. iJo Baculites Faujasii. 315 Scaphites aequalis. 310 Head of Mosasaurus of Maastricht. 380 CAINOZOTC STRATA. CHAPTER XII. CAINOZOIO STEATA. We have now arrived at the last system of strata deposited in the sea and in lakes ; before, as is usually stated, the present races of land animals and plants were called into existence. It is usually stated to be limited as to time between the era of the chalk and the beginning of the modern zoological period ; but this definition is something arbitrary in application. As we have seen, on previous occasions, the several systems of strata, however distinct in the great mass, gradually soften into each other at the lines of junction, and sometimes exchange beds, so as to form the whole into a natural and connected series, so it may be with the present set of deposits in relation to the chalk. In England, indeed, as already remarked, this kind of transition from the chalk to the tertiaries, is nowhere distinct, nor are we entitled to say decidedly that at any point on the Con- tinent of Europe it is completely ascertained. The blending, however, of tertiary and cretaceous rocks would, if established at many points, occasion no peculiar difficulty in their arrangement, nor alter one just inference o!rawn from previous obser- vations. It is to be expected, from everything that is known of similar cases, that the great and abrupt change between the chalk and tertiaries in England and in France will be in some other countries divided into easier gradations, and thus the maxim natura nonfacit saltus, will be found to prevail in this case as in all others. A greater difficulty, however, occurs when we attempt to mark the modern limit of the tertiary system of strata, arising out of several circumstances important in their history, which scarcely required notice amongst the older deposits. The ancient systems of strata were for the most part marine ; but the tertiary system includes many estuary and lacustrine deposits, which sometimes alternate with the marine strata, sometimes appear unconnected with them, and in several instances were evidently altogether independent of them and of each other, being formed separately upon the elevated lands under the influence of the ordinary processes of drainage. Now as similar causes have been in operation long since the tertiary era, and are in operation at present, it is often for this reason very difficult to say what is really the geological antiquity of a lacustrine deposit, whether it be of the present period, or belonging to the tertiary or some intermediate system. Within the tertiary era a variety of land mammalia came into existence which are now extinct, and which it appears had become GENERAL CONSIDERATIONS. 381 extinct before the. glacial detritus was scattered, and the elephant and hysena were destroyed in northern climes. Taken in order of time, we may mark with some confidence, at least two characteristic groups of terrestrial life, by the older Palaeotherian and the less ancient Mastodontoidal or Elephant oidal races. The former belong to the lower groups of tertiary strata, those called by Lyell Eocene, as formed at the dawn of the recent period. The latter occur in his Meiocene and Pleiocene groups, in which the analogy to existing nature grows stronger and stronger till it becomes a real and intimate affinity in the Pleistocene deposits. In a few cases palaeotherian and masto- dontic remains occur together, and help to prove that the changes from the earlier to the latter system of organic nature were, like all the preceding, gradually accomplished ; that before the palseotheria had become extinct, the ox, mastodon, and rhinoceros had begun to exist. The tertiary class is often stated to include only the deposits which happened before the present system of organic nature was established. But do geologists really admit what these words imply ? We who have used these terms, and have come to reflect on their meaning, answer certainly not, either in theory or in practice. For the present system of organic nature is most certainly recognized in nearly all the marine tertiary strata, if we trust to the evidence which in every other such case has been thought the best : viz. the marine shells. The shells of all the tertiary marine strata are proved by various degrees of evidence to belong to the present system of organic nature, for the genera are almost universally the same, though the numerical analogy of the species is very unequal in different deposits. Neither is it true, that what are called lacustrine tertiaries can in all cases be pronounced to contain exuviaB of another system of organic nature : for if this could hardly be asserted of the basin of Paris, what is to be said of Aix and (Eningen ? It can hardly be doubted that the land accumulations are capable of being classed by the reliquiae of land animals which they contain ; and this classification is helped in northern zones by the striking phenomena of the glacial era, which separate into two groups the more recent postglacial, from the more ancient preglacial quadrupeds. As these remains lie often in lacustrine, and sometimes in marine sediments, which contain shells and other forms of life, the pheno- mena of land-life became comparable with those of the waters, and thus with proper caution the laws of succession of life forms become of general application. To be consistent, however, we must certainly allow that the races of land animals might be altogether changed without any correspond- ing change of lacustrine or marine shells, and we must limit our classifications to their just application. We must judge of the age 382 CAINOZOIC STRATA. and other characters of supracretaceous marine strata by comparison with what is known of the modern condition of the sea ; the lacus- trine deposits of the same era must be compared to the standard of the modern lakes; and the terrestrial accumulations will derive illustration from comparison with the modern state of the land, and the aqueous agencies upon it. In some instances at present, and it is to be expected that hereafter many more will be established, the relative epochs of certain terrestrial, lacustrine, and marine phenomena have been determined, but it is not the less certain that these phenomena belong to three independent series, which must be studied apart before they can be understood together. It must be evident, from what has been said before, that a consider- able proportion of the old strata had at the commencement of the tertiary system been raised above the sea, some parts by violent, others by gentle and continued elevation. In the latter way, we imagine, the chalk and oolites of England to have been a little raised above the sea at this period, so as to leave broad planes of the chalk rising gradually from the sea, and, of course, exposed to the violence of its waves, and other parts dry and fit for the growth of plants and the residence of animals. In France the same effects may be sup- posed to have happened round the greater part of the basin of Paris, while the old granitic rocks of central France had some time before raised themselves to nearly their present altitude, and constituted a shore for the oolites and the chalk. The mountains of Brittany, the chains of the Cevennes, the Jura, and the Vosges were also con- spicuous in France, while the Black Forest, Odenwald, Harz, Erzgebirge, and Bohemian mountains generally had assumed their present relative heights. Also all the primary tracts of Britain, Scandinavia, Finland, and the Ural had long since circumscribed the ancient sea, or basin of Europe. But as yet the Pyrenees and Apennines, the Alps and Carpathians, had been only partially raised from the deep sea, though enough it would appear to divide the ocean into limited seas, gulfs, and bays, in which the tertiary strata were to be deposited. This brief sketch will convey a tolerable notion of the observed extent of the tertiary deposits in Europe. The eastern and south- eastern parts of England, a large tract round Paris, another equally large area in the south-west of France, detached deposits in the Loire and the Allier, the valley of the Rhone, the valley of the Ehine from Basle to Mayence ; the great hollow between the Jura and the Alps, the plains of the Danube and the Po, the subapennine region, many points in southern Spain, the central basin of Bohemia, these are the tracts at present best known, but they are not the most extensive. From the Ardennes, Harz, Biesengebirge, Carpathians, and Caucasus, great part of the space north-eastward to the CAINOZOIC PEBIODS. 383 primary rocks of the Ural and Finland is composed of a variable mass of tertiary rocks resting on secondary and primary formations. The eastern coasts of North America, large areas in Northern Africa and in the region south of the Himalaya, are covered by tertiary rocks. As far as appears at present, the marine parts of these deposits were formed beneath waters, some of which were connected with the German Ocean, as the eastern parts of England, the northern parts of Germany, &c., others with the English Channel and the Atlantic Ocean, as the south of England, Paris, Bourdeaux, and the remainder branched off from the Mediterranean, the Black Sea, the Sea of Azof, the Caspian, &c. As in the present day the molluscous productions of one sea are distinguishable from those of another, by differing according to latitude and local circumstances, according to the nature of the coasts, influx of rivers, and many other causes, so we may expect the case to have been formerly. This is found to be the fact. The tertiary strata have several common and characteristic features, but they show differences of great importance, both mineralogical and organic, which clearly indicate the difference of circumstances of their production. In the following tabular view, an attempt is made to fill with British phenomena the interval between the age of the chalk and the present period, and thus to place in one succession, geological, pre- historical, and historical time. In all that relates to the older marine portions of the tertiaries, we are specially indebted to Prestwich ; the late Professor Forbes corrected our notions in regard to the lacustrine groups ; Charlesworth, Wood, and Lyell, have cleared the horizon of the crag ; Trimmer, Smith, Morris, and almost all English geologists have contributed to the illustrations of those later glacial and postglacial deposits, on whose animal contents, Buck- land, Cuvier, and Owen have bestowed such successful attention.* HISTORICAL, PERIOD. Coins, constructions of civilized f Fens, marshes, and river deposits f man, with remains of domesticated j Cambridgeshire, Lincolnshire, Yorkshire, animals, and races extinct in com- j Lancashire, and many parts of Britain paratively late periods. ^_and Ireland. PREHISTORICAL PERIOD. Rude instruments, marks of f Broad gravel beds, deposited in valleys uncivilized structures, earliest | by fresh water as in the Upper Thames kinds of burials, remains of red<( and Cherwell Valleys lacustrine depo- deer, long-fronted ox, common ox. | sits, &c., the level of the land nearly as it * This method of classification is exemplified in my recent work, entitled " Rivers, Mountains, and Sea Coast of Yorkshire." t Geologists should be careful to remember that man is of more recent date in the western than in the eastern part of the world. 384 CAINOZOIO STRATA. POSTGLACIAL, PERIOD. The red deer, long-fronted ox, f Shell marls under peat and other the Irish elk, Urus priscus, hippo- j lacustrine and marine deposits, with living potamus, elephant ; forests of <{ species of shells and insects, the level of modern trees. | the land somewhat variable, but for a time ^higher than now. GLACIAL PERIOD. (Sea.) Marine shells of arctic type. f The northern drift of gravel, clay, sand, &c., and erratic blocks transported by \ floating ice, and urged by currents of the | sea; the land being much depressed in l^ northern zones. PREGLACIAL PERIOD. Forests of modern trees ; Irish f Lacustrine and peaty deposits, local elk, elephant, hippopotamus, ! gravels, under glacial detritus, bone hysena, Felis spelsea, cavern bear, j caverns ; land higher than its present &c. (Jevel. CRAG PERIOD. (Sea.) Cetacea, mastodon, rhinoceros, f Littoral deposits on the shores of the Felis lutra ; shells numerous, of | German Ocean, when the land was at a existing genera, frequently of { somewhat lower level than now (mam- existing species. I malia plentiful). Coralline and shell [_ deposits farther from shore. DISCONTINUITY OF SUCCESSION HERE. MEIOCENE STRATA WANTING IN BRITAIN. UPPER MARINO-LACUSTRINE PERIOD. Palseotherium, anoplotherium ( Fresh water and marine deposits of chaeropotamus, &c.; shells of exist- < Hempstead and Bembridge in the Isle of ing genera. (Wight. LOWER MARINO- LACUSTRINE PERIOD. Shells of existing genera. ( Fresh water and marine deposits of 1 Headen Hill. BARTON PERIOD. Shells, numerous, mostly of ( Marfne ar ^ llaceous ^ arenace ous g existing genera, but not often of 4 depositg> I existing species. (. * BRACKLESHAM SERIES Arenaceous, argillaceous, and lignitic BOGNOR PERIOD. deposits. Shells, numerous, mostly of f existing genera, rarely of existing J ^^ ^^^ and arenaceous species; land animals mostly of { g ^ extinct genera Coryphodon, hy- racotherium, didelphys, macacus. [_ THANET PERIOD. Shells, few, analogous to those f Marfne and fluviatile d j shelk'btlow meSOZ 1C | pebbles ' C loured dayS ^ ' ands: We must here observe that there is no case where the crag over- lies the fresh water beds, they being found only in separate districts belonging to different basins of the tertiary area. Notwithstanding PLASTIC CLAY GKOUP. 385 the want of direct sections, comparisons with the tertiary strata of other districts warrant us in classing the crag as a more recent deposit than the lacustrine heds. EOCENE DEPOSITS consist of several principal groups which are in many cases very distinctly characterized, and always appear to indicate considerable difference in the state of the waters which produced them. The plastic clay group consists, generally, of green, yellow, and white sands, with or without marine shells, layers of rolled flints, occasionally furnishing attachment to oysters, clays and marls of a yellowish or bluish colour with shells, and sometimes of many various tints, and then mostly devoid of shells. Beds of lignite also occur in the sands of this group. The sections of the plastic clay group are usually considered to be very irregular and confused, and so, indeed, they are, and mark, upon the whole, a turbulent period and varying velocities of water. Prestwich classes them in three groups, thus placed in descending order : Upper part (basement bed of the London clay) pebbly. Middle part consisting of blue clay, or marl, with cerithia, and other shells, or mottled plastic clays, sometimes alternating with sands, with or without shells (Wool- wich and Reading series). Lower part containing green sands often associated with flints and pebbles, and occa- sionally full of oyster shells, sharks' teeth, &c. (Thanet sands.) The following section of Loam Pit Hill, near Lewisham in Kent, by Dr. Buckland, will serve to convey a good notion of the general characters of the plastic clay and Thanet sands group near London, except that the quantity of rolled pebbles is smaller than usual : London Clay above. Feet. Striped sand, yellow, fine, and iron-shot 10 Striped loam and plastic clay, containing a few pyritical casts of shells, and some thin leaves of carbonaceous matter 10 Yellow sands 3 Plastic clay , Lead-coloured clay containing impressions of leaves 2 group. ' Brownish clay containing cythereae, estimated at 6 Three thin beds of clay, of which the upper and lower con- tain cytherese and the middle oysters 3 Loam and sand, in its upper part cream-coloured, and con- taining nodules of friable marl, in its lower part sandy and iron-shot 4 B ed of ferruginous sand containing flint pebbles 12 Coarse green sand, containing pebbles 5 Thanet sands Ash-coloured sand, slightly micaceous, without pebbles or S I H U I S ..... O j Green sand identical with the Reading oyster beds, contain- ^ ing green-coated chalk flints, but no organic remains... 1 Chalk with beds and nodules of black flint. 2c 386 EOCENE STEATA. The green sandy lower part of the group, with or without pebbles, oysters, and other shells, and sharks' teeth, appears to be nearly con- stant and very characteristic, being found at Sudbury, Beading, Woolwich, &c. ; scarcely occurs in the Isle of Wight. The blue shelly clays of the middle part are well developed and rich in fossils, about Woolwich and other parts of Kent ; in the Isle of Wight mottled clays of greater thickness (100 feet and more) appear, arid constitute nearly the whole deposit between the shelly London clay and the chalk. At Newhaven, they much resemble the Woolwich beds in their zoological contents, and contain Websterite. The range of the middle or truly plastic clay group, appears to be greater than of those immediately above or below. Prestwich's elaborate sections trace it from Kent to the Isle of Wight. In the eastern part of this range a marine character prevails among the organic remains ; in the middle part they have a fluviatile and estuary character, (e.g., Woolwich,) and in the western part the strata are mostly unfossiliferous, (ostrea bellovacina, however, is found there.) The organic remains are enumerated by Prestwich.* They consist of two bryozoa, five genera of foraminifera, seven species of entomostraca, two species of monomyaria, twenty-eight species of dimyaria, (no brachiopod,) one annelid, twenty-seven species of gasteropoda, four or more fishes, a chelonia, a coryphodon, and phalangal bone of a bird. In the western district are layers of leaves. Prestwich is of opinion that the ' Druid sandstone' called also ' grey weathers,' and ' Sarsen stone' which lies on the chalk hills of Wilts and Dorset, is an exceptional product of this series. The London Clay is a very simple argillaceous deposit, of considerable but variable thickness, usually from 300 to 400 feet about London, and reaching 480 feet in Sheppey. It thins from this point in all deviations, gradually, and still retains in the Isle of Wight, where it was till lately included in the plastic clay series, a thickness of 200 feet to 300 feet. It is usually of a lead-gray, or blue colour, but dull brown and red clays occur in it, perhaps most usually in the lower part. Green grains are often observable in it, a few sandy layers occur, and these, usually containing green sand, are indurated at Bognor and Selsea into a considerable rock. Sept aria abound in it, and some imperfect laminae of marly limestone have been noticed. It lies upon the plastic clay group over considerable tracts in Essex, Berks, Hertfordshire, Middlesex, Hampshire, Surrey and Kent, on the northern side of the Wealden ridge, borders the southern coast from * Geol. Journal, vol. x., p. 117. BAGSHOT SAND AND BRACKLESHAM BEDS. 387 Worthing to Hordwell, and separates the lower coloured clays of the Isle of Wight from the Bracklesham sands and clays and Barton clays and fresh water deposits above. It is chiefly interesting for the number, beauty, and variety of its organic remains, of which the cliffs at Sheppey are rich repositories. Considerable quantities were also obtained in cutting for the Archway at Highgate. There appear to be as many as four zones of organic remains in this clay, in the eastern district. The contents of each were given by Prest- wich, in the Geol. Journal, 1854. Having been much exposed to watery action, which it could ill resist, it is often left in insulated hills, upon the substrata of sands and clays. Mineral springs, so common to blue clays, rise in con- siderable number from the London clay near the metropolis. The most remarkable are those of Epsom, famous for their sulphate of magnesia, Bagnige Wells, and Acton. It yields little water to the well-sinker, but on being pierced to the sands below, or, as circumstances may require, to the chalk, great streams of water rush up, and may even overflow the surface if the chalk hills which gather and transmit the water be sufficiently elevated. This is the case about London, under which subterranean streams flow from the chalk of Surrey on one side, and that of Hert- fordshire on the other. The London clay possesses all the characters of a very quiet and continuous deposit, perhaps in deep water, yet not far from shore, since many vegetable seeds, wood, and other considerable remains of land and littoral productions occur in it, as wood, turtles, and crocodiles, but no pebbles nor coarse sands. The temporary turbulence of the plastic clay period had wholly passed away, and only finer sediment in great quantities found its way to the sea. Shells of the most delicate and fragile forms are perfectly uninjured in this clay, except in the rare case of its being laminated. Bagshot Sand and Bracklesham Beds, The Bagshot sand was described by Warburton. Its place is above the London clay, on which it rests in the only districts in which as yet it has been much noticed. Bagshot Heath and Hamp- stead are the principal localities near London. Its fossils are few and imperfect, but are thought by Warburton to resemble some of those found in the upper marine formation of the Paris basin. Prestwich has examined the characters and geographical range of this thick and variable group. In the Isle of Wight, it was long included in the plastic clay and sand group, the true London clay in the cliffs there being insufficiently valued. According to Webster's 388 EOCENE STKA.TA. measure, these beds, vertical at Alum Bay, are there 864 feet thick, the lower part consisting of yellow irony sands, and thin alternating clays are supposed to correspond with the lower Bagshot sands near London. The upper part, a mass of alternating sands, variously and brilliantly tinted red, orange, yellow, green, black, white, with some dark and light clays and layers of lignite, is the series of Bracklesham Bay. It is in Alum Bay poor in fossils, but elsewhere that is not the case ; for in this group many species occur in Whitecliff Bay (Isle of Wight), at Southampton, and Bracklesham. Barton Clay Group. This body of uniform dark clay, with scattered green grains, is conspicuous in vertical strata at the north end of Alum Bay Cliff, and again in the steep beds at Whitecliff Bay. In its thickness of 250 feet, are many layers of shells which, running up the cliff in parallel lines, offer the most unequivocal proof of the upturning of the strata through an arc of 90 ; to this group belong most of the shells of Hordwell Cliff. Headen Hill Group. Above the Barton clay we find in the Isle of Wight about 100 feet of white and yellow sand, without organic remains, in beds much less inclined than those already noticed. These Headen sands are the base of the well-known fresh water marls and limestones of Headen Hill. These fresh water beds are in two groups, " upper " and " lower," parted by 36 feet of layers of purple and green marls, full to admiration of estuary and marine shells, distinct from those of the subjacent tertiary clays. Among them are potamida, by myriads, natica, neritina, voluta, fusus, ancilla, cyclas, venus, eythersea, ostrea, &c. The "lower fresh water" beds, 63 feet, including some sands below, of Headen hill, are formed in many layers of marly and sub- calcareous bands, containing Limnsese, planorbes, &c., with slight partings of an estuary character. The " upper fresh water " beds are on the whole more stony, and more calcareous than the lower series, the total thickness, including some clays at the top of the hill, is above 70 feet. In several respects the section at the east end of the Isle of Wight is more satisfactory than that which the well-known and famous cliffs of Alum Bay have yielded. It has been somewhat misunder- stood; but Forbes's latest researches* have satisfactorily shown the occurrence on White Cliff Bay, of an upper fresh water group, * Geological Journal, 1853. DISLOCATION OF THE ISLE OF WIGHT. 389 (that of Bembridge,) separated by 100 feet of other strata from the lower one of Headen hill. The latter is here more marly than at Alum Bay. The series of fresh water beds is even here not complete, there being a still higher group at Hempstead, between Newtown and Yarmouth. At Whitecliff Bay, the beds above the Headen fresh water group, called St. Helen's Beds, consist of a marine lacustrine series, 100 feet thick. Above the calcareous beds, about 30 feet deposited from fresh water and brackish water, and then the Bembridge Beds, 80 feet thick, consisting of marls, sands, and limestones, partly marine or brackish, with an oyster bed and cerithia, but mostly of fresh water origin. The Binstead quarries belong to this group, and yield palseotheria and anoplotheria, with some land shells. Finally comes the uppermost group of the island, the Hempstead Beds, 170 feet thick, consisting of fresh water and estuary marls, carbon- aceous clays, and marine sands and clays. These are the latest of the tertiary strata in the south of England, and of very limited extent, being confined, as far as at present known, to a hill on the coast between Yarmouth and Newtown, and a tract inland, near Newport, called Parkhurst Forest. Professor Forbes regards the whole series as "Eocene," but the upper part may perhaps be com- parable with strata, which on the continent receive the designation of " Meiocene." Dislocation of the isle of wight. For our knowledge of the fresh water tertiary strata of England, we are indebted to Webster. They exist only along the northern side of the Isle of Wight, and on the opposite coast of Hampshire. The chalk and older strata, with the plastic clay and sands, and the London and Barton clays of the Isle of Wight, they were subject to convulsive movements. At Headen Hill the fresh water strata seem at first sight to have been deposited horizontally after great disturbance. They were not really inde- pendent of that great movement : at White Cliff Bay they are obviously and greatly elevated by it. There one might at first suppose the still higher fresh water strata of Bembridge to have been deposited level after the disturbance ; but that is not the case. The great convulsion of the Isle of Wight bears a date later than that of the highest strata there anywhere visible. 390 EOCENE STEATA. ORGANIC REMAINS. PLANTS. PHANEROGAMIA. MONOCOTYLEDONEA. Flabellaria, . 1 POLYCOTYLEDONEA. Callitrites, . 4 Frenellites, . 4 Solenostrobus, 5 DICOTYLEDONEA. Amentaceae, . 1 3 1 1 Cupanoides, . 8 Faboidea, . . 25 Hightea, 10 Lauraceaa, 1 Leguminosites, . 18 1 Nipadites, 12 Petrophylloides, 7 Tricarpellites, 7 Wetherellia, 1 Xulionosprionites, 2 FORAMINIFERA. 1 Anomalina, . 1 1 Cristellaria, . 2 2 6 Frondicularia, 1 Globigerina, . 1 2 1 Marginulina, 1 Nodosaria, 6 1 CRYPTOGAMIA. No. of Species. L. Eocene. M. Eocene. U. Eocene. 1 1 1 1 1 8 25 10 1 18 1 12 7 7 1 2 OEQANIC EEMAINS. 391 Nummulites, 4 Operculina, . 1 Polymorphina, 1 Quinqueloculina, . 3 Robulina, 2 Rosalina, . 2 Rotalina, 2 Textularia, 2 Triloculina, 1 Truncatulina, 1 ZOOPHYTA. ALCYONABIA. Graphularia, 1 1 Websteria, . 1 ZOANTHARIA. Astrocasnia, . 1 Balanophyllia, 1 Dasmia, 1 Dendrophyllia, 2 Diphelia, 1 Holaraea, 1 Litharaea, 1 Paracyathus, 3 2 Turbinolia, . 8 ECHINODERMATA. ECHIXOIDEA. Cidaris, 1 1 Echinopsis, . 1 Echinus, 1 Hemiaster, 3 Schizaster, . 1 Spatangus, . 1 ASTEEOIDEA. Astropecten, . 3 Goniaster, 3 Ophiura, 1 CRINOtDEA. Bourguetocrinus, . 1 Cainocrinus, . 1 Pentacrinus, 3 No. of Species. L. Eocene. M. Eocene. U. Eocene. 4 1 1 3 2 1 2 2 1 1 392 EOCENE STBATA. ANNELIDA. No. of Species. L. Eocene. M. Eocene. U. Eocene. Ditrupa, . . . ' 2 ... 2 Serpula, . .... 5 ... 5 Vermicularia, .... 1 ... 1 Vermilia, 1 ... 1 CIRRIPEDIA. Balanus, 1 ... 1 Pollicipes, 2 ... 2 Scalpellum, 1 ... 1 CRUSTACEA. BKACHYUKA. Xanthopsis, .... 4 ... 4 MACRUBA. Archseocarabus, .... 1 ... 1 Basintopus, 1 ... 1 Hoploparia, 1 ... 2 ENTOMOSTRACA. Cythere, 1 ... 1 Cytherella 2 ... 2 BRYOZOA. Cellepora, 1 ... 1 Eschara, 1 ... 1 Flustra, 1 ... 1 Idmonea, 1 ... 1 Lunulites, 1 ... 1 BRACHIOPODA. Terebratula, .... 1 ... 1 Terebratulina, .... 1 ... 1 MONOMYARIA. Anomia, 1 ... 1 Avicula, 3 ... 3 Lima, 2 ... 2 Ostrea, 18 4 14 Pecten, 10 1 9 Pinna, 3 ... 3 Spondylus, 1 ... 1 Area, . . 11 Astarte, 3 Cardita, 8 . 11 Chama, . ... 1 Corbula, . 13 Crassatella, . 4 Cryptodon, . 2 Cucullaea, 1 Cyclas, 1 Cypricardia, . 2 Cyprina, 3 Cyrena, . 12 Cytherea, . . 17 Diplodonta, . 1 Dreissena, 1 Gastrochsena, 3 Glycimeris, . 1 Isocardia, 1 Leda, . 3 Limopsis, 2 Lucina, . 12 Mactra, 2 Modiola, 8 Mya, . . 1 Mytilus, 1 Neaera, 3 Nucula, 11 Panopaea, 5 Pectunculus, 6 Pholadomya, 5 Pholas, ' . 2 Potamomya, . 2 Psammobia, . 3 Sanguinolaria, 2 Solecurtus, . 1 Solen, . 5 Syndesraya, . 1 Tellina, . 24 Teredina, 1 Teredo, 1 Thracia, 3 Unio, . 2 Venus, . 1 PTEROPODA. GASTEROPODA. Achatina, 1 Actaeon, 4 OEGANIC EEMAINS. 393 DIMYARIA. No. of Species. L. Eocene. M. Eocene. U. Eocene. 341 2 1 8 2 9 2 1 2 1 2 444 3 13 1 1 1 3 1 1 111 2 11 1 2 161 1 1 3 11 1 131 1 5 2 3 2 2 1 2 2 1 5 1 24 1 1 1 2 1 1 1 394 EOCEITE STRATA. Adeorbis, 'No. of Species. 1 Ancillaria, . . 4 Ancylus, * . . 2 Aporrhais, . . . 1 Auricula, 1 Bifrontia, 5 Buccinum, . 5 2 Bulla, . . 12 Calyptrsea, . 2 Cancellaria, . 6 Cassidaria, . 5 Cerithium, . . 32 Chemnitzia, . 1 Clausilia, 1 9 Craspedopoma, 1 Crepidula, 1 ( 'uina. . 1 Cyclostoma, . 1 Cyclotus, 2 Cypraea, 9 Delphinula, . 1 Dentalium, . 6 Emarginula, . 1 Eulima, 4 Fasciolaria, . 3 Fissurella, . 1 Fusus, . . 31 Helix, . 9 Hipponyx, . 2 Hydrobia, 5 Limnsea, 21 Littorina, 1 Marginella, . 8 Melampus, . 1 Melania, 9 Melanopsis, . 6 Mitra, . 7 Murex, . 12 Nassa, . 1 Natica, . 23 Nematura, 1 Nerita, 3 Neritina, 4 Odostomia, . 2 Oliva, . 3 Ovula, 1 Paludina, 5 Parmophorus, 1 Pedipes, 1 2 Planorbis, ... 14 Pleurotoma, . . . . 31 L. Eocene. M. Eocene. U. Eocene. 1 4 1 1 1 1 5 5 1 2 12 1 2 6 5 4 26 2 1 1 1 1 2 1 4 3 1 3 28 1 1 2 2 2 21 1 8 1 1 6 1 2 7 12 1 1 22 1 3 2 2 3 1 1 2 1 1 2 1 8 31 ORGANIC BEMAINS. 395 Potamidum, . No. of Species. L. Eoc 8 Pseudoliva, . 4 Pupa, . ... 2 Pvramidella, 1 Pyrula, 4 Ringuicula, . 3 RosteUaria, . 5 Rotella, 1 Scalaria, 8 Sigaretus, 1 9 Strombus, 1 Succinea, 2 Terebellum, . 2 Terebra, 1 Triton, 3 Trochus, 1 Turbo, 1 Turritella, . . 15 Typhis, 3 Voluta, . 31 Volvaria, 1 CEPHALOPODA. Belemnosis, . 1 2 Belosepia, 3 Nautilus, 6 PISCES. PLACOroEI. Myliobatidoe. Myliobatis, . 18 Actobatis, 6 Pristidce. Pristis, 4 Lamnidce. Carcharodon, 2 Lamna, 6 Nictitantes. Galeocerdo, . 1 Glyphis, 1 Naisia, 1 Notidanidce. 1 Chimceridce. Psaliodus, . 1 Edaphontidce. Edaphodon, . 3 M. Eocene. 8 4 1 4 3 5 1 8 1 9 1 1 2 1 3 1 1 15 3 30 1 U. Eocene. 396 EOCENE STKATA. Elasmodus, Otodus, Spinax, No. of Species. L. Eocene. M. Eocene. U. Eocene. 1 ... 1 Sturionidce. GANOroEI. 1 Salamandroidei. Lepidosteus, Pycnodontidce. Gyrodus, 2 1 Periodus, Pycnodus, Phyllodus, . 1 1 6 Pisodus, Gymnodontidce. Teratichthys, 1 1 Lophiidce. Loxostomus, Bknniidce. Liparus, Scomberidce. Acestrus, Bothrosteus, . Coelocephalus, Coelopoma, . Coelorhynchus, Cybium, Echenus, Naupygus, . Phalacrus, . Phasganus, . Rhonchus, Scombrinus, Tetrapterus, . Gadidce. Ampheristus, Goniognathus, Merlinus, Ebinocephalus, Schomberesocidce. Hypsodon, Labrophagus, Platylaemus, . Sphyrsenodus, CYCLOIDEI. 1 OBGAffIC EEMAINS. 397 No. of Species. L. Eocene. M. Eocene. U. Eocene. ClupddcB. Megalops, 1 ... 1 1 ... 1 Murcenidce. Rhynchorhinus, . . , 1 ... 1 Dubice,} Pachycephalus, ... 1 ... 1 fam.j Rhypidolepis, ... 1 ... 1 Glyptocephalus, .... 1 ... 1 Gadopsis, ..... 1 ... 1 Characidce. Brychsetus, 1 ... 1 Siluridce. SUurus, ..... 1 ... 1 CTENOIDEI. Percidce. Brachygnathus, .... 1 ... 1 Coeloperca, 1 ... 1 Eurygnathus, .... 1 ... 1 Myripristis, 1 ... 1 Percostoma, ..... 1 ... 1 Podocephalus, .... 1 ... 1 Synophrys, 1 ... 1 Scienuridce. Sciaenurus, 2 ... 2 Labroidce. Auchenilabrus, .... 1 ... 1 Theutyidce. Calopomus, ..... 1 ... 1 Pomophractus, .... 1 ... 1 Ptychocephalus, .... 1 ... 1 REPTILIA. Crocodilida. Alligator, 1 ... 1 Crocodilus, 3 ... 3 Gavialis, 1 ... 1 Lacertida. Lacertse, 1 ... 1 Ophidida. Palseophis, 4 ... 4 Paleryx, 2 ... 2 Chelonida. Chelone, 13 ... 13 Emys, 6 ... 6 398 EOCENE STEATA. AVES. No. of Species. L. Eocene. M. Eocene. U. Eocene. Platemys, 2 ... 2 Trionyx, . . ."' 10 ... 9 1 Halcyornis, ...'.. 1 ... 1 Lithornis, ....... 1 ... 1 Genus? ... 2 MAMMALIA. Pachydermata. Anoplotherium, .... 2 ... ... 2 Chseropotamus, .... 1 ... ... 1 Coryphodon, .... 2 ... 2 Dichobune, 1 ... ... 1 Dichodon, 1 ... 1 Hyopotamus, .... 2 ... ... 2 Hyracotherium, .... 2 ... 2 Lophiodon, 1 ... 1 Microchaerus, .... 1 ... 1 Palaeotherium, .... 5 ... ... 5 Paloplotherium, .... 1 ... ... 1 CETACEA. Balama, 1 MARSUPIALIA. Didelphys, 1 INSECTIVORA. Spalacodon, 1 CHEIROPTERA. Vespertilio, 1 QUADRUMANA. Macacus, NOTE. In the preceding lists, L. Eocene includes the Cainozoic strata below London clay ; M. Eocene, the London clay, Bracklesham beds, Barton clay, and Headen beds ; U. Eocene, the strata of Bembridge and Hempstead. EOCENE FOSSILS. 399 317 Nummulite in limestone. 318 Cerithium giganteum. 319 Tumtella imbricataria. 320 Arapullaria acuta. 323 Crassatella sulcata. 318 ?2l Terebellum fusifonne. 322 Mitra scabra. 400 EOCENE STRATA. 324 Cardium porulosum. 325 Skeleton of the common anoplotherium. 326 Skeleton of the great palasotherium. 327 Limnaea longiscata. 328 Planorbis eaomphalus. 329 Chara medicaginula. 401 MEIOCENE STRATA ARE BELIEVED NOT TO OCCUR IN THE BRITISH ISLES. 2 I) 402 PLEIOCENE STRATA. CHAPTEE XIII. PLEIOCENE STBATA. Crag. Range and Characters. The most recent of all the marine stratified deposits, is also one of the most irregular. It occurs only in the eastern part of England over a narrow space of little elevation from the cliffs of Walton in Essex to beyond Aldborough in Suffolk. It is also known to some extent in Norfolk, particularly at Bramerton near Norwich, and has been found at Bridlington. . In this short course the crag is found to rest on the London clay at Walton and Bawdsey, and on chalk at Bramerton, being evidently a much later deposit than either, and wholly independent of them. It exhibits also considerable variation of character. Its general aspect in numerous pits in Suffolk is a ferruginous mass of shells, dark pebbles, and bones and teeth of fishes and reptiles, mixed up in a confused mass of sand, sometimes grouped into beds, and sometimes exhibiting oblique and disordered laminae, very much resembling the general character of a modern very shelly beach. And from the manner in which it lies in the country about Ipswich and at Bramerton, there can be little doubt that it is really an ancient beach of the Grerman Ocean. But about Aldborough and Orford the crag assumes a totally different character, becoming, in fact, a zoophytic limestone, an accretionary rock, formed by the cementation of coralline reliquia3, shells, and calcareous sand, probably after the manner of the Guadeloupe accretionary limestone, and a similar littoral formation on the coast of the Isle of Ascension. This coralline limestone contains some of the most characteristic shells of the ordinary crag, and is clearly of the same era, or only one stage earlier than that heterogeneous deposit. Charlesworth was led by his study of the crag deposits to consider them in three groups, thus placed and named : Upper group or Fluvio-marine Crag of the vicinity of Norwich, &c. Mammalia, littoral shells. Middle group or Red Crag of Suffolk. Mammalia, reptiles, fish, and multitudes of invertebrata, often much waterworn. Lower group or Coralline Crag of Suffolk. Few or no mammalia, abundance of invertebrata, not waterworn. shells of the Crag. The quantity of shells contained in the ordinary red pebbly crag of Suffolk is beyond all calculation. The name of crag is, we believe, derived from a British word (cragen) signifying SHELLS OF THE CEAG. 403 shell, and the Suffolk pits have been for a long time in work solely to manure the ground with the calcareous exuviae. Lately, taught by Henslow their value, the farmers have extracted from the lower part of the Ked Crag abundance of bones, and coprolites, rich in phosphate of lime, and very valuable for manure. The bones are mostly rolled, and it has been supposed that some are derived from London clay drifted, in fact, from that older deposit. The number of species here buried is also very great. Upon comparing them with recent kinds we are presented with very curious and striking results. There are several of the crag shells so exceedingly similar to recent shells of the German Ocean, that it is impossible to distin- guish them. Turbo littoreus retains its colour, many others are with difficulty separated by minute discrimination ; but some, as the corals of Orford, pecten princeps, terebratula Dalei, and others, are evidently unlike anything now existing in the G-erman Ocean, and indeed not now to be paralleled in any part of the world. A small number of the crag shells appear very similar to some in the Eocene clay, but in general they have few common analogies, and the most cursory observer must be struck by the total difference of general aspect. The London clay shells recall to our memory the shores of a tropical climate, the crag fossils speak to us of an ancient race of shells more resembling those of our own seas. But the corals are sui generis, and upon the whole, those geologists who are most desirous of uniting the crag deposit to the present system of Nature, must acknowledge that it bears the stamp of an ancient and peculiar era. In Smith's work, (Strata Identified,) the tooth of a mastodon is figured from a noble specimen now, with this original collection, deposited in the British Museum, but without mention of locality. According to my recollection of what was stated to me by Smith, when his specimens were removed to the museum, and at other times, it was picked up under the diluvial cliff at Happisburgh, from which so many elephantoidal teeth and bones have fallen into the sea. The late Mr. Woodward (Syn. Table, 1830,) referred it to Whitlingham, near Newark, where such teeth in the same state of preservation have been found. And Mr. Woodward, now of the British Museum, states that Mr. Smith, in 1836, confirmed that reference. A very unexpected addition to the list of organic remains of the crag, is the badger, (probably undistinguishable from the common European species,) of which good specimens of the skull and leg bones are in the Yorkshire Museum. It may, however, be a case of later burrowing into the crag deposit. The bones usually dug at the base of the red crag belong to whales, mastodon, hippopo- tamus, deer, &c. It must evidently be of little use to give sections of such a deposit as the ordinary crag. We shall therefore subjoin only Mr. E. Taylor's 404 PLEIOCENE STEATA. account of the Bramerton pit, and mention that, in general its thick- ness is about 30 feet, and its greatest height above the sea, in Walton le Naze, 50 or 60 feet. Feet 1. Sand without organic remains 5 2. Gravel 1 3. Loamy earth 4 4. Red ferruginous sand, containing occasionally hollow ochreous nodules 1* 5. Coarse white sand, with a vast number of crag shells If 6. Gravel with fragments of shells l| 7. Brown sand, in which is a seam of minute fragments of shells 6 inches thick 15 8. Coarse white sand with crag shells, similar to No. 5, tellinae and murices most abundant 3 9. Red sand, without organic remains 15 10. Loamy earth, with large stones and crag shells 1 Total 49 Large irregular black flints crowded together in situ in the chalk. Attached to these flints are echini, terebratulae, inocerami, and belemnites 1 Chalk to the bed of the river 15 PLANTS. Nullipora, FORAMINIFERA. Amphistegina, Anomalina, Biloculina, Dentalina, Glandulina, Globigerina, Globulina, Guttulina, Nodosaria, Nonionina, Operculina, Planorbulina, Polymorphina, , Polystomella, Quinqueloculina, Robulina, . Rotalina, . Spiroloculina, Textularia, Triloculina, Truncatulina, 3RGANIC REMAINS. x of Species. ZOOPHYTA. 1 Alcyonium, Flabellum, 1 Sphenotrochus, 1 ECHINOIDEA. 5 Amphidetus, 2 Brissus, 1 Echinocyamus, 2 Echinus, . 2 Spatangus, 5 Temnechinus, 3 ASTEROIDEA. 1 2 Uraster, . 1 CRINOIDEA. 1 Comatula, . 5 ANNELIDA. 2 g Cyclogyra, 2 Ditrupa, 5"" Serpula, 9 Spirorbis, . 4 Vermilia, . 3 CIRRIPEDA. 4 Acasta, No. of Species. 1 1 1 ORGANIC EEMAINS. 405 Balanus, . Coronula, . Pyrgoma, . Verruca, . CRUSTACEA. Atelecyclus, Cancer, Ebalia, Fortunus, . Pagurus, . Alecto, Cellaria, . Cellepora, . Crisia, Diastopora, Discopora, Eschara, . Fascicularia, Filicella, . Flustra, Hippo thoa, Honiera, . Lepralia, . Lunulites, . Melicertina, Membranipora, Eetepora, . Theonoa, . Tubulipora, BRACHIOPODA. Argiope, . Discina, Rhynconella, Terebratula, Terebratulina, MONOMYARIA. Anomia, . Avicula, . Lima, Ostrea, Pecten, Pinna, DIMYARIA. Area, Artemis, . Astarte, . Cardita, Cardium, . Chama, No. of Species. No. of Species. 9 Cochleodesma, , Coralliophaga, 1 ( Corbula, . 2 m Cryptodon, 2 Cyamium, . 1 Cyclas, . 1 . Cyprina, . 2 . Cyrena, 1 . Cytherea, . 3 . Diplodonta, 3 . Donax, 3 Erycinella, 1 Gastrochsena, 2 $ 1 Glycimeris, I .-. 2 Isocardia, . 1 5 Kellia, 9 . 2 Leda, 6 . 1 4 . . 1 Limopsis, . 2 . 6 Lucina, ! 4 . 1 Lucinopsis, 1 . 1 Lutraria, . - 2 . 5 Mactra, 7 . 1 Modiola, . 9 . 2 Montacuta, 5 9 Mya, 4 2 Mytilns, . 4 . 1 Nesera, 2 2 Nucinella, . 1 . 1 Nucula, 5 1 Pandora, . 1 . 8 Panopsea, . 3 Pectunculus, 3 Petricola, . 1 i' 1 Pholadomya, 1 2 Pholas, 4 . 1 Psammobia, 2 1 Saxicava, . 1 . 1 Scrobicularia, 1 Solecurtus, 3 Solen, 3 5 Sphenia, 1 1 Syndesmya, 2 Tapes, 4 2 Tellina, 10 10 Teredo, 1 1 Thetis, 1 Thracia, . 5 Venerupis, 1 * 2 Venus, 6 ; 20 Venericardia, 1 t 6 . 11 PTEROPODA. 1 Cleodora, .... 1 406 PLEIOCETTE STEATA. GASTEROPODA. Aclis, Actseon, Adeorbis, . Aporrhais, Buccinum, . Bulla, Calyptraea, Cancellaria, Capulus, . Cassidaria, Cerithium, Chemnitzia, Columbella, Conovulus, Cypraea, . Dentalium, Emarginula, Erato, Eulima, Fissurella, . Fossarus, . Fusus, Helix, Hydrobia, Limnsea, Litiopa, Littorina, . Margarita, Marsenia, . Mitra, Murex, Nassa, Natica, Odostomia, Ovula, Paludina, . PateUa, . >. of Species. No. of Species. Planorbis, . 4 1 Pleurotomaria, 19 4 Purpura, . 2 5 Pyramidella, 2 I Pyrula, 1 2 Einguicula, 1 9 Rissoa, 12 1 Scalaria, 13 ,.: 4 Scissurella, 1 2 Sigaretus, . 1 . 1 1 Succinea, . 2 8 Terebra, . 2 11 Trichotropis, 1 1 Triton, 1 2 Trochus, . 17 5 Turritella, . 7 3 Valvata, . 1 2 Velutina, . 3 2 Vermetus, 1 3 Voluta, 1 1 1 CEPHALOPODA None mentioned. 12 5 PISCES. 4 3 Carcharodon, ... 1 1 KEPTILIA? 2 3 Otodus, .... 1 BIRDS ? 1 2 MAMMALIA. 13 Mastodon, . 11 Rhinoceros, 4 Asinus, 1 Felis, 3 Lutra, 4 Balsenodon, PLEIOCENE FOSSILS. 407 330 Balanus crassus. 331 Rosteliaria pes pelecani. 332 Pecten pleuronectes. 333 Teeth of Mastodon. 334 Pleurotoma rotata, 335 Buccinum prismaticum. 339 Cypraea coccinelloides. 336 Voluta Lamberti. 337 Murex alveolatus. 338 Astarte Basteroti. 408 PLEISTOCENE DEPOSITS. CHAPTER XIV. PLEISTOCENE DEPOSITS. The uppermost group of the crag deposits, with its mastodon, rhinoceros, &c., may perhaps be nearly the fluvio-marine equivalent of the ferruginous gravel and irregular lacustrine deposits, under glacial drift, of the Happisburgh Cliff, or have immediately preceded it. In this deposit at Happisburgh lie bones of elephant and hippo- potamus, ox, deer, and other animals, some of which also occur in the lower part of the glacial drift. A gravel deposit of corresponding age is found under glacial drift at Hessle, near Hull, and there yields bones of elephant, horse, ox. Probably to this date we may refer many of the most celebrated bone-caves, as those of Kirkdale and Kent's Hole in England, the bear caves of Grailenreuth, &c. In this period the old sea bed was enough raised to constitute dry land, probably continuous land, from Britain to the Continent. Following this condition of things came a great depression of the northern zones in Europe and America. By this operation, the land sinking to form again the bed of the sea, we have acquired those great masses of "diluvial," or "detrital," or "glacial" clays and boulders which are so striking a part of the superficial deposits of Britain. This was succeeded by a farther elevation of the sea bed, whose effects are continued in part to this day. Thus three main divisions of the pleistocene deposits of Britain come strongly into notice. Preglacial land and fresh water deposits, glacial marine deposits, postglacial land and fresh water deposits. For the purpose of placing these phenomena in a steady light, we shall first treat of them in a district where the whole series is well represented, and continued to the modern epochs. Such a district is found in the eastern parts of England, as in Norfolk and York- shire. We take the latter tract for our type, according to the sub- joined general scale : c POSTGLACIAL PERIOD. Peat deposits, lacustrine deposits, river deposits, sea beaches. b GLACIAL PERIOD. Marine deposits, clay with irregular stones drifted from a distance, partially worn, or rolled pebbles, or erratic blocks, gravel beds, sand beds, shell beds interspersed. a PREGLACIAL PERIOD. Local drifts of gravel and sand, lacustrine marls, bone deposits in caves. Preglacial deposits of gravel occur at Hessle, near Hull, and on the cliffs north of Bridlington, in each case resting upon the chalk. The gravel is composed of chalk and flint fragments, but DESCRIPTION AND VARIETIES OF. 409 little worn ; it is accumulated to the depth of a few feet or a few yards in thickness, sometimes aggregated into a sort of breccia. It seems to have been collected by local watery actions of no great violence, or of long duration, for the bones of quadrupeds which it contains are little or not at all water worn. These bones belong to elephant, a small species or variety of horse, ox, deer, and they have as yet only been found at Hessle. At Bielbecks, near Market Weighton, the new red marl is excavated into little hollows, a few hundred yards in length ; these hollows are partly filled with gravel, sands, and clays ; the mode of aggregation varying from place to place. In one of these hollows the red marl was first covered by alternating argillaceous marls and local flint gravel, a few feet in thickness, without any organic remains. Over these lay about 12 feet of black marl, containing minute pebbles of chalk and a few small plants, and at the bottom two or three pieces of fine grained sandstone. In this marl were thirteen species of land and fresh water shells, viz., three land shells, Helex nemoralis, Helix caperata, Pupa marginata; one swamp shell, viz., Succinea amphibia; nine fresh water shells, viz., Limnsea limosa, Limnaea palustris, many specimens, Planorbis complanatus, many specimens, P. vortex, P. contortus, P. nitidus, P. spirorbis, Valvata cristata, Pisidium amnicum ; with them occurred remains of Elephas primi- genius, Rhinoceros tichorhinus, Bos urus, antiquus, large Cervus (probably C. megaceros), large horse. Felis spelsea, wolf, bones of a duck, an elytron of chrysomela, and a seed-vessel of some umbel- late plant complete this catalogue of early terrestrial life. Above the black marl was found gray marl with rolled pebbles of quartz, mountain limestone, and sandstone of the carboniferous series, with chalk and flint 5| feet thick. Here also occurred bones of elephant, horse, rhinoceros, and deer, but no shells or vegetable matter. Gravel and yellow sand, with chalk and flints, pebbles of quartz and sandstone, four feet and a-half thick, covered the whole, making a perfectly even surface, but sinking irregularly into the subjacent gray marl.* The operations whose traces are thus disclosed appear to have begun with local action of water drifting materials from the foot of the neighbouring wolds of chalk and flint, which rest on blue clays. In a comparatively quiet period the nearer stratified deposits, (lias clays,) seem to have furnished the whole matter for the de- posit, which, doubtless, was collected beneath the waters of a marshy pool, which nourished planorbes and IhnnsesB, and received, by occa- sional currents, helices and succinsee from the adjacent plants. The gray marls above contain evidence of greater currents of water flow- * Harcourt, Phil. Mag., 1830. Phillips's GeoL of Yorkshire, vol. i., p. 140. 1836. 410 PLEISTOCENE DEPOSITS. ing from greater distances, bringing fragments from the western borders of Yorkshire, as well as others from the neighbouring hills ; but the greater mass is still marly clay. The top is again the effect of local watery action. Nothing appears in any part of the excava- tion to indicate watery action, from beyond the drainage of what is near Yorkshire. Such gravelly deposits as those here described were covered in some neighbouring parts of Yorkshire by the ordinary 1 1 1 1 .v, * * boulder clay.* A deposit of perhaps the same age as that of Bielbecks, was opened in the valley of the Aire, near Leeds,t in a sort of bay, of the old boundary of the valley. In the clay which here occurred, at a depth of nine feet, (20 feet above the river,) remains of hippopotamus major were found in admirable perfection ; the tusks, teeth, cranium, examined by Mr. Denny, indicated several individuals. In this valley deposit, parts of Elephas primigenius, horse, stag, Bos primi- genius, Bos latifrons, Cervus elaphus, and goat, have been found associated with hippopotamus. Trunks of trees, as oak, and fir, and hazel nuts, occur with them. Whether we should refer to the same period the bones of hippo- potamus and other animals found by Strickland, with 24 species of land and fresh water shells, in the valley of the Avon at Cropthorn, near Evesham ; J the hippopotamus figured by Lee, from the marls of north Lancashire, under peat ; the hippopotamus from the fresh water beds of Brentford, described by Trimmer, 1813 ; the elephant, beaver, and other mammals of Copford, recorded by Brown, || may be somewhat doubtful. It is remarkable how often the remains of the old river horse have been found in lacustrine and marsh deposits, and how nearly perfect his skeletons have been. In the case near Evesham, the bones were drifted, perhaps from still earlier lacustrine sediments, higher up the valley of the Avon. Two of the shells there found in fine sand under the bones are said to be of extinct species. At Copford, in the lowest bed of gray sandy gravel, occur 7 land and fresh water shells. Above this is a blue boulder clay, 11 feet thick, with fragments of stone, and many fossils derived from Yorkshire, Lincolnshire, and other localities. It contains 9 fresh water shells, and 3 entomostraca ; and bones of elephant, urus, stag, bear, and beaver. On this blue clay is a layer of vegetable matter in a wedge-shaped mass, from 3 inches to 7 feet thick, an argillaceous peat, containing Valvata piscinalis, and Cyclas rivicola, in groups. Over this a white shell marl, 1 to 6 feet thick, with 48 land shells, two of them (Helix incarnata, H. ruderata) of extinct species ; and 22 swamp and fresh water shells. Here occur bones of ox, stag, * Mr. Trimmer regards the deposit here described as of later (postglacial) date. Geological Journal, 1851. t Denny in Eep. Brit. Assoc., 1853. J Geol. Proceedings, ii., 111. Phil. Trans. || Geol. Journal, 1852. OSSIFEEOTJS CAVERNS SITUATION OF. 411 and elephant. Over all is a continuous widely spread reddish-brown clay, 1 to 6 feet thick, with chalk, flint, sandstone, limestone, con- flomerate, and porphyry fragments a tooth of horse occurred in it. n one locality this is covered by peat, with shells of recent species. Between the reddish-brown boulder clay above, and the reddish and gray gravel below, the shelly clays, peats, &c., are found in basins of limited extent, ancient lacustrine sediments. In the preglacial de- posit at Happisburgh, already noticed, we have the further informa- tion of the condition of the surface, which fir trees rooted on the fluvio-marine crag, leaves, and seed vessels may give. The remains of elephant are here very numerous, and associated with bones of ox, deer, and horse. The deposit seems to have extended far to the east, many hundred molar teeth of the elephant having been dredged up by the fishermen from the oyster beds out at sea. The deposits in Yal d'Arno, which yield elephant and mastodon the elephant supposed by Nesti to be of a different species (Elephas meridionalis) from that most usual in Europe (E. primi- genius) may be of the same age as these preglacial accumulations of the Norfolk coast. The elephantine remains of Happisburgh have been sometimes referred to the Tuscan species or variety. The old lacustrine deposits on the east flank of the Ural which contains mammoth bones and gold, may belong to the same period, and doubtless many of the localities in Germany and France, which yield elephants' bones and land and fresh water shells, should be placed in the same part of the scale of geological time. To the preglacial era belong, we think, the greater number of ossiferous caves and fissures, containing elephant, hippopotamus, hya3na, and other extinct species of animals. Those who desire to follow at length the detailed history of caves and osseous breccia must be referred to the luminous pages of Buckland (Reliquiae Dilu- viance), and that imperishable monument of genius, the Ossemens Fossiles of Cuvier. We shall here present a simple analysis of the leading results of their inquiries bearing on the subject before us. Caverns and fissures containing bones, however preserved, and of whatever kinds these are, present some important characters in common. (1.) Ossiferous Caverns, how situated. In the first place they are, we believe, always situated in limestone, very generally in stratified limestone, though this character is sometimes denied to the dolo- mitic limestone of the Mediterranean shores. This circumstance has, however, apparently no relation whatever to the accident of the caves containing bones, but is merely a general fact characteristic of limestone ; for in this kind of rock nearly all the caverns, grottos, and remarkable natural fissures in the world are situated. And as far as we have observed, there is no reason whatever in speculations 412 PLEISTOCENE DEPOSITS. on the origin of the bone caverns and fissures to exclude those of similar forms in which no bones occur. (2.) This being the case, we may remark further, that though in some cases the existence of the cavern may be thought to be con- nected with dislocations of the strata, as at Grreenhow Hill, in York- shire, yet this is rather the rare exception than the general rule. The carboniferous limestone is full of caverns, yet not more so where numerous slips and veins divide it than in other places. Veins of lead ore hardly ever lead to these caverns, and it is a matter of general remark, that though the strata may be disturbed near them, the disturbance has little to do with the caverns. (3.) Most caverns, whatever be the character of their floor, as- sume at intervals along their length, the appearances of a great fissure in the rocks. This circumstance must have been often observed by those familiar with the caves of Somersetshire, Derbyshire, and Yorkshire, and is recognized even in that least favourable example, Kirkdale Cave, which in its nearly level course keeps its floor nearly on one particular bed of the rock, but occasionally opens upwards into narrow irregular expansions or fissures. The fissures filled with breccia may, in fact, be often regarded as exposed caves, and re- semble them in all essential circumstances. (4.) Very few of these cavities in the rocks are entirely free on their sides and roof from remarkable depressions and cavities, like those produced on limestone by currents of water, or the slow consuming agency of the atmosphere. Many of them which now convey water, and are not inerusted with stalagmite, as the Peak Cavern in Derbyshire, show this sort of watery erosion so strongly as to impress most beholders with a conviction that the whole was excavated by the running stream. (5.) Several writers, in particular Brongniart, have attempted to show that mere water has no effect in eroding rocks. This may, perhaps, be true of the oxyde of hydrogen, but is certainly not a cor- rect account of the effect of common water, and particularly of water containing carbonic acid, and traversing limestone rocks. The innu- merable petrifying springs of limestone countries at once demon- strate the inaccuracy of this reasoning. The very rain from the heavens eats away these stones rapidly. The springs which issue from limestone generally contain carbonate of lime, and most of them yield a large quantity of free carbonic acid upon exposure to the air. (6.) How Formed. Those accustomed to underground works know it as a familiar fact, that the water which is absorbed by dry limestone land, takes particular channels through the rocks, down the joints, and along certain fissures. Every limestone hill in the carboniferous district of the north of England, shows in its swallows and moor pits the OSSIFEEOTJS CAVERNS HOW FORMED. 413 erosive power of the atmospheric water. We shall, therefore, venture from all these considerations to maintain the enlargement or excava- tion of these caverns to be principally owing to the subterranean passage of water charged with carbonic acid, the direction of this water, and its power of erosion, being favoured by fissures and other causes. If the altered drainage and other circumstances of a country so far change the course of the water as to leave these subterranean channels almost dry, the small quantity of moisture continuing to arrive, may slowly deposit stalagmite over the surfaces formerly eroded, and the cave change its appearance altogether. An acci- dental inrush of water from another source may deposit mud or pebbles, and this be also covered up by another layer of stalagmite. It is no great objection to this view, that the cavities are some- times exceedingly irregular, for water in its subterranean course must follow the original cracks of the rocks. Indeed, upon a review of this matter, that very irregularity may perhaps be thought an argu- ment in favour of the mode of origin here suggested. The most remarkable ossiferous caverns in England are Kirkdale Cave near Kirkby Moorside in Yorkshire, the Dream cavern near Wirksworth in Derbyshire, Banwell Cave in the Mendip Hills, Kent's Hole near Torquay, Oreston near Plymouth, Cefn near Denbigh, and Paviland near Swansea; in Germany, the slopes of the Harz moun- tains give us the caves of Baumann, of Biel, and of Schwarzfeld. Between the Harz and Franconia is the Bear Cavern of Glucksbrunn ; the Jura formation near Baireuth is celebrated for the rich associated caverns of Gailenreuth, Schoanestein, Brunnenstein, Holeberg, Wieserloch, Geissloch, Wunderhohle, Kabenstein, Kuhloch, Zahnloch, Schneiderloch, Rewig, &c. In Westphalia the same oolitic forma- tion has the caves of Kluterhohle, and Sundwich. The Caves of Adelsberg in Carniola and the Dragons' Caves in Hungary have also yielded bones. In France, instructed by Dr. Buckland's researches, two caverns, rich with bones, have been described by M. Thirria near Vesoul, and several others near Montpellier and Narbonne by Marcel de Serres, Tournal, Christol, &c., and one near Miremont by M. de la Noue. Osseous breccia appears singularly connected with the coasts of the Mediterranean. It occurs at Gibraltar, in Languedoc, and at several other points in the south of France, at Antibes, Nice, Pisa, Cape Palinurus, North of Bastia, (Corsica,) Cagliari, (Sardinia,) Maridolce, (Sicily,) in Dalmatia, Aragon, &c. Ferruginous breccia, in which bones are associated with pisolitic iron ore, occurs in Wur- temberg, and in Carniola, in Jura limestone. low filled with Bones. In some of these caves hyaenas lived and dragged into them for food the bones of other animals existing in the vicinity ; bears died in others ; some were filled by the accidental 414 PLEISTOCENE DEPOSITS. falling in of browsing quadrupeds, and others heaped with a mixture of bones, mud, and pebbles brought by general or local floods on the surface. We shall give an abstract of the characteristic facts attend- ing each of these cases. Kirkdaie Cave is one of the most remarkable instances of ossiferous cavities known in England, both from the number of species and abundance of the bones of quadrupeds found there, their state of conservation, and other attendant circumstances. The entrance of this cave is on the side of a narrow valley 30 feet above the stream, in a nearly level and perfectly undisturbed bed of coralline oolite. It had a sort of vestibule, much larger than the interior windings of the cave, and in this, according to Salmond, lay a considerable proportion of the large bones of elephant, rhinoceros, &c. Beyond this was a STEP in the floor, of the thickness of one bed of limestone, leading to the interior recesses, which follow an irregular line, occa- sionally rising to the height of 14 feet, but generally under 4 feet, and about the same breadth, but liable to contractions in both their measures. The floor was generally overspread and its inequalities filled up by a layer of mud, of calcareo-argillaceous substance, such as might be supposed derivable from the joints and partings of the limestone. In some places the mud was more coarse and sandy. Stalagmite in considerable quantity had dripped from the roof, in- crusted the sides, and covered like a sheet the layer of mud rising upon its surface into mammillary tubercles. In the mud, and protruding occasionally through its stalagmitic covering, lay the bones of six or seven carnivora, hyaena, tiger, or lion, bear, wolf, fox, and weasel ; three pachydermata, viz. elephant, rhinoceros, hippopotamus, the horse ; four ruminantia, ox, and three kinds of deer ; four rodentia, hare, rabbit, water rat, mouse ; besides five birds, raven, pigeon, lark, duck, and a bird of the size of a thrush. The bones were scattered over this long area, "as over a dog kennel," almost universally broken to pieces, not as if by common fracture, but by violent biting and gnawing : marks of teeth are discernible on many, exactly like those left by living hyaanas on similar bones submitted to their jaws. Hyenas' teeth in great numbers, of ah 1 ages, milk teeth, shed teeth, and worn to stumps in the jaws of the animal, abounded in the cave, besides a considerable quantity of osseous fa3cal matter, like that of the modern hyasna. From these data, most of which may be verified on the numerous specimens extracted from the cave, Dr. Buckland infers, that hyenas were for a long period the undisputed tenants of this den, lived in it for many generations, dragged into it for food, piecemeal, the bodies of animals then living in the neighbourhood, and were finally dis- possessed of their hold by an irruption of water which let fall the muddy sediment now enveloping the bones. The ordinary action of KTJHLOCH CAYE. 415 the water passing through the calcareous rock then covered the whole with stalagmite, and closed up the bones from the destructive agency of moisture and air. This accounts for the conservation of their gelatine. Few conclusions of this precise nature appear better supported by the facts of the case, and when we reflect on the re- markable analogy, in almost all points concerning the state and con- servation of the bones, of the cavern at Torquay called Kent's Hole, and contrast these particulars of the hycena dens with those of the ox caves in Mendip, we shall feel a full conviction that Dr. Buckland's bold theory is a true interpretation of nature. Cave of Kuhioch. The caves of Franconia appeared to Dr. Buck- land to have been tenanted by bears which died in the retired parts, and were there mixed more or less with sediment and pebbles brought by subsequent diluvial floods, and the whole covered over by a sta- lagmitic crust formed in the usual way. The cavern of Gailenreuth is perhaps the most magnificent example of this doctrine ; but that at Kuhioch presents some peculiarities of a very interesting kind. " It is literally true that in this single cavern (the size and propor- tions of which are nearly equal to the interior of a large church) there are hundreds of cart-loads of black animal dust entirely cover- ing the whole floor, to a depth which must average at least six feet, and which, if we multiply this depth by the length and breadth of the cavern, will be found to exceed 5,000 cubic feet. The whole of this mass has been again and again dug over in search of teeth and bones, which it still contains abundantly, though in broken frag- ments. The state of these is very different from that of the bones we find in any other caverns, being of a black or more properly speaking dark umber colour throughout, and many of them readily crumbling under the finger into a soft dark powder resembling mummy powder, and being of the same nature with the black earth in which they are embedded. The quantity of animal earth accu- mulated on this floor," continues Dr. Buckland, "is the most sur- prising and the only thing of the kind I ever witnessed ; and many hundred, I may say thousand individuals must have contributed their remains to make up this appalling mass of death. It seems in great part to be derived from comminuted and pulverized bones ; for the fleshy parts of animals produce by decomposition so small a quantity of permanent earthy residuum, that we must seek for the origin of this mass principally in decayed bones. The cave is so dry that the black earth lies in the state of loose powder and rises in dust under the feet. It also retains so large a proportion of its original animal matter that it is occasionally used by the peasants as an enriching manure for the adjacent meadows." This cave is entered by a lofty arch, above the river Erbach, expands within both in height and breadth, and terminates in two chambers closed at the end. No 416 PLEISTOCENE DEPOSITS. fissures enter this cave ; and it has no other exit than the entrance above named, except a very small passage to the same valley. These circumstances are considered by Dr. Buckland to explain the absence of diluvial accumulations in this cave. There is no appearance of either stalagmite or stalactite having ever existed in this cavern. Ittendip Cares. Dr. Buckland's views concerning the ancient occu- pation of hyaenas and bears of the caves of Kirkdale and Franconia derive much elucidation from the discoveries of other caverns in which the animal remains appear to have been accumulated in a dif- ferent manner. We shall mention those of Hutton in the Mendip Hills, and of Oreston near Plymouth ; the former disclosed by ochre works, the latter by quarrying for limestone. The ochre of Mendip Hills appears, in some cases, to be derived from the decomposed strata of the vicinity, and deposited in caves and fissures of the lime- stone, either by water continually passing downwards by filtration, or by some more transient and violent operation. In pursuing one of these mines of ochre near the village of Hutton, bones of many animals were discovered ; and the circumstances were examined by the Rev. Mr. Catcott, from whose manuscript Conybeare has drawn up a clear account of this remarkable occurrence. The elevation of the ochre pit was 300 to 400 feet above the sea. " The ochre was pursued through fissures in the limestone, occasionally expanding into large cavernous chambers, their range being in a steep descent and almost perpendicular. In opening the pits the workmen, after removing 18 inches of vegetable mould and 4 feet of rubbly ochre, came to a fissure in the limestone rock, about 18 inches broad and 4 feet long. This was filled with good ochre, but contained no bones. It continued to the depth of 8 yards, and then opened into a cavern about 20 feet square and 4 high. The floor of this cave consisted of good ochre, strewed on the surface of which were multi- tudes of white bones, which were also found dispersed through the interior of the ochreous mass. In the centre of this chamber a large stalactite was suspended from the roof, and beneath a similar mass rose from the floor almost touching it. In one of the side walls was an opening about 3 feet square, which conducted, through a passage, 18 yards in length, to a second cavern, 10 yards in length and 5 in breadth, both the passage and cavern being filled with ochre and bones. Another passage, about 6 feet square, branched off laterally from this chamber about 4 yards below its entrance. This continued nearly on the same level for 18 yards. It was filled by rubbly ochre, fragments of limestone, and lead ore confusedly mixed together ; many large bones occurring in the mass, among which four magnificent teeth of an elephant were found. In the second chamber, immediately beyond the entrance of the branch just described, there appeared a large deep opening, tending perpendicularly downwards, filled with OBESTON CAVES. 417 the same congeries 6f rubble, ochre, bones, &c. This was cleared to the depth of 5 yards. This point, being the deepest part of the workings, was estimated at about 36 yards beneath the surface of the hill." * The bones found in Hutton Hole belong to elephant, rhinoceros, ox, horse, deer, hyaena, bear, a nearly complete skeleton of a fox, hog, and some gnawing animal. Orcston Caves. Three deposits of bones at Oreston, near Ply- mouth, have been detected by Mr. Whidby during the removal of the entire mass of a hill of Devonian limestone for the construction of the Breakwater. The first deposit (1817) lay in a cavern 15 feet wide, 12 high, and 45 long, and about 4 feet above high-water mark. This cavern was filled with solid clay, in which teeth and bones of rhinoceros were embedded. The second discovery (1820) was of a smaller cavern, distant 120 yards from the former, 1 foot high, 18 wide, and 20 long, and 8 feet above high-water mark. But the greatest extent of subterranean cavities was exposed in 1822, by the intersection of apertures in the middle of the limestone, containing an immense deposit of bones and teeth embedded in clay. Dr. Buck- land describes in a very graphic manner the irregular branching or insulated fissures and caverns which were at this time laid open in an artificial cliff 90 feet high, their various direction, loamy contents, and relation to similar cavities not containing bones in the neigh- bouring limestone cliffs. He remarks that the fissures and caverns are so connected, so often confluent and inosculating with each other, and so identical in their contents, that there appears to be no differ- ence as to the time and manner in which they were filled. In many of those which are nearly vertical, the communication is obvious, but those which pass obliquely, and consequently seldom lie in the plane of the cliff, may appear to close upwards. In almost all the cavities there occurs a deposit of mud and sand, and angular frag- ments of limestone ; these substances sometimes entirely fill up the lower chambers, and are lodged in various proportions on the shelves and ledges and in lateral hollows of the middle and upper regions. In one large vault it is sorted into laminae ; sometimes it is inter- spersed with extraneous fragments of quartz and clay slate ; stalag- mite sometimes invests it ; in some few spots were balls of ironstone, and concretions of ochre formed in the clay ; in others was a con- siderable quantity of manganese ore, sometimes in concentrically coated balls. The bones collected in the Oreston caverns and fissures belong to hyaena, tiger, wolf, fox, horse, ox, deer. The bones of the horse predominated ; those of ox and deer were also abundant. We may admit, without hesitation, that these caverns and fissures at Oreston were filled with this mingled mass of earthy, stony, bony, * Reliq. Diluv. 2E 418 PLEISTOCENE DEPOSITS. and metallic matters, by aqueous action ; and there seems no good reason to doubt that partly in this manner, and partly by the accidental falling of quadrupeds into open fissures of the limestone, many other caves in Somersetshire, Derbyshire, &c., have been stored with their animal remains. Osseous Breccia of the mediterranean. Prom such cavernous fis- sures, filled with mingled fragmentary masses, as those of Oreston, there is hardly a step to the fissures or caves containing ossiferous breccia at so many points around the Mediterranean Sea. Almost every limestone rock, wherever its interior structure can be seen on the sea coast, in ravines, in mines, is found to be traversed by fissures and excavated in caverns: it was therefore to be expected that such should be exposed in abundance in the calcareous precipices of the northern shore of the Mediterranean. But it is very remarkable that they should be in those regions so generally productive of bones ; that these should so generally be found in a reddish coloured loamy breccia, holding fragments of the neighbouring rock, helices, and other spoils of the land ; and that no marine production whatever should be found mingled with the mass, though, as at Santo Giro, near Palermo, (Geological Proceedings, 1833,) there be proofs of the marine submersion of the actual cave, before the introduction of the bony breccia. There is clearly no necessary relation between the existence of these ossiferous cavities and the proximity of the sea ; in many cases their exposure may be owing to the waste of the coast, but in others it must be mainly ascribed to the convulsive elevation of the land at some ancient period. In all cases the production of caverns and fissures in the rocks is the work of causes acting during periods long anterior to those when the animal remains were intro- duced. Thousands of cavities have been produced in the rocks, and filled with mineral treasures, and buried beneath vast depths of con- solidated strata, of very high antiquity ; such of them as were by any causes exposed at the surface, have been filled with clay, or heaped with fragments of rock, and in the great majority of instances lined with calcareous spar, and in countries which were then in- habited by quadrupeds some have been partly filled by bones. The geological era, when the latter occurrence happened, is rendered de- finite only by a rigid anatomical examination of the bones ; and by this Cuvier has taught us that we may confidently refer the great majority of the quadrupedal remains, whether found in gravel on the surface, in the mud, gravel, breccia, or stalagmite, or on the naked floor of subterranean caverns, to one zoological period. In general, the most abundant remains in the ossiferous breccia of the Mediter- ranean shores belong to the orders ruminantia and rodentia ; bones of ursine, feline, and canine animals, as well as those of hippopotamus and elephant, are rare. This is exactly what should happen upon GLACIAL DEPOSITS. 419 the supposition that the bones in the fissures were derived chiefly from animals which fell into them, for these naturally should consist principally of herbivorous tribes. The presence of land shells, of fragments of the neighbouring rocks, the abundant interlacement of stalagmitical carbonate of lime, tends exactly to the same conclusion ; and even the redness of the breccia of Gibraltar, Cette, &c., is pro- bably owing to .the ferruginous nature of the neighbouring rocks. The influence of local causes is thus clearly indicated, and in the opinion of Cuvier, these have operated through considerable periods, so that the bones and fragments of rocks fell successively into the cavity, and the calcareous cement was gradually accumulated. If, in addition, we suppose, with Dr. Buckland, that these same cavities have since undergone the action of moving water, which might drift in heaps the fragmented bones and stones, and mix with them loam and occasionally pebbles, all the phenomena seem naturally explained, and the theory of the ossiferous breccia becomes connected with that of the proper cavern deposits. For particulars respecting the ossiferous breccia of Gibraltar, Cette, Antibes, Nice, Pisa, Cape Palinurus, Corsica, Sardinia, Sicily, Dalmatia, Cerigo, Aragon, and the Veronese, we must refer to Cuvier's admirable Ossemens Fossiles, torn. iv. Glacial Deposits. We have now passed through a long history of the deposits formed i on the beds of the ancient sea, in its depths, along its shores, and in : its estuaries, and we have noticed its contemporaneous or alternating accumulations from the fresh waters which then flowed upon the earth. The tertiary system of strata, by showing us remarkable | alternations of fresh water and marine deposits, appears to establish a connection between the ancient and the modern world, between the j subaqueous and the elevated land. The whole of that system presents us with strong analogies to j the present order of things, in its races of animals and plants; and ( its fresh water deposits have often a clear relation to the present j level of the continents, and on this account might be viewed as the I oldest of the modern formations. Yet upon closer inquiry it will be found that in many cases a very j strong line of distinction is drawn between the tertiary formations ( and the accumulations from actual seas, rivers, and lakes, by the in- \ tervention of an irregular mass of deposits, evidently produced by j inundations of extraordinary height and powerful action upon the 1 face of the dried and inhabited earth. These deposits are so ex- j: tensive, and over large tracts of the earth's surface have so much of a common character, that they have very generally been classed 420 PLEISTOCENE DEPOSITS. as the productions of one turbulent period in the process of the for- mation of the globe, and termed the diluvial deposits. Origin and Use of the Term. This term was first employed by Smith, and when subsequently adopted by the English School of Geology, it was often understood to refer to the effects of the No- achian deluge; and though on this point opinions are now more unsettled and various, the term may still be very properly em- ployed by geologists of every school to mark the effects of turbulent inundations upon limited tracts of the inhabited land, happening within a particular period in the history of the globe. But its effects are not traceable universally ; they are perhaps limited to the north circumpolar and temperate zones ; and thus the term cannot be used with advantage in the sense generally assigned to it. Without entering upon the unprofitable history of the delusions in which geologists have involved themselves on the subject of the Noachian deluge, it will be proper to remark that all discussions of this nature are useful or injurious according as they are carried on independently of or in connection with theology. Burnet and Woodward, by mixing up false hypotheses with scriptural history, retarded the progress of geological science, and sanctioned a perverse and uncritical application of the Mosaic narrative to support every new, fanciful, and unsubstantial theory. We must bear in mind that it does not follow that all deluges must be referred to the Noachian flood ; certainly many turbulent waves have traversed parts of the globe before the creation of man ; some local deluges have happened since the days of Noah. The tur- bulent waters of which we are now to trace the effects upon the surface of the earth, may be quite independent of the deluge of Scripture ; we have no right to assume any connection between them ; and it will be prudent, before entangling ourselves in fetters which it may be difficult to unclasp, to wait for a full investigation of the subject. Many curious questions of time and circumstance are involved in such a comparison, on which a prudent philosophy especially Christian philosophy will be slow to pronounce a decision. There is nothing in geology less improbable than the occurrence of a period of violent watery action, for in the course of our survey of the stratified rocks, we perceived clearly that, during their pro- duction, long periods of regular and ordinary action have been fre- quently succeeded by temporary disturbance. The epochs of these disturbances relatively to other phenomena are precisely assignable. They differ in importance, and while some are so great and extensive as to afford means of classifying the strata over large surfaces of the globe, others seem to have happened locally and irregularly. The present system of nature may be considered as one of the periods of regular action, and the effects now produced upon the land DBIFT FROM MOUNTAINS. 421 and in the sea are of the same kind as those occasioned during the comparatively tranquil periods of older nature, because upon the whole the levels of sea and land are constant. But the deposits called diluvial are characteristic of a period of watery tumult and disturbance of the most extensive kind, and are to be associated mentally with other great epochs of disturbance which mark tem- porary convulsions in the ancient system of nature. This watery tumult differs, however, from all anterior deluges, by the circumstance that we are looking upon the land and reading there the traces left by violent waves, while those of ancient times are, for the most part, known to us only by the effects they produced in the sea. Proofs. We shall now present the proofs of such a system of tur- bulent waters having passed over large portions of the surface' of the inhabited earth, since the formation of all or nearly all of the strati- fied rocks now visible above the ocean, and since the present conti- nents were dried, elevated, and inhabited. Detritus from the Cumbrian mountains. Without venturing to assert that every region of the earth's surface is covered by the water-moved ruins of rocks, and waste of distant mountains, in situa- tions to which existing streams could not carry them, we may state that observations of this nature are general for all parts of the con- tinent of Europe, and frequent in Northern America, countries which have been, better than any other, explored by geologists. In all these regions, great deposits of gravel, sand, and clay, containing in more or less abundance portions of all the known rocks and strata, lie spread over formations of every age, primary, secondary, and tertiary. There is no order in the arrangement of these heteroge- neous materials, no constant series or succession of deposits, but the utmost confusion and irregularity. The materials lie sometimes in valleys, often on hills, crossing in their course both hills and valleys, and appearing to have little relation to the track of the existing streams, though sometimes evidently influenced by the great physical features of the districts. Though the subject of the direction of diluvial currents, with reference to local geography, has not been sufficiently attended to, even in England, we are able to bring forward some striking instances in support of the preceding statements. It is well known that the mountain group of Cumbria encloses remark- able kinds of granite, syenite, and other rocks, and that they are separated from the eastern parts of the island by a long unbroken range of carboniferous limestone stretching from the Tyne to the Aire. A considerable hollow everywhere divides these ranges ; and in some parts, as in the vale of Eden, the hollow is from 1,000 to 2,000 feet, or more, below the summits on either hand. The lowest point in the whole line of carboniferous limestone, which offers itself directly to the west, is on Stainmoor, about 1,440 feet above the sea. Now, 422 PLEISTOCENE DEPOSITS. by the force of the currents of water alluded to, blocks of the curious porphyritic granite of Shap Pells have been removed from their original sites, (1,500 feet above the sea,) swept over a ridge of lime- stone rocks about Orton, into the red sandstone vale of Eden, 500 feet above the sea, and from this deep and ancient vale lifted up the steeps of Stainmoor to the very summits of the pass. From thence they have been urged forward as from a new centre, and spread in a radiating manner over the south of Durham, and the whole extent of the vales of York and Cleveland, to the foot of the Hambleton hills and the Wolds. Against these great barriers, considerable quantities of the rocks of Cumberland, and likewise of the carboni- ferous system of Yorkshire, are collected, but a large portion of the debris has also travelled over and beyond parts of these high districts and reached the sea side, where many of the cliffs are covered by blocks swept from Cumberland and North-Western Yorkshire. In passing from Shap Fells to Holderness, the granitic boulders have been transported across two deep vales, and over two elevated ranges of hills. In passing over these hills, we clearly perceive that the blocks were wafted by the easiest ascents. This is remarkably the case at Stainmoor, not the lowest point in the long carboniferous summit, but the one which directly faced the mountains from which the blocks started, and the only one crossed by the diluvial boulders. It is therefore evident that at the period when these violent waters flowed over the north of England, the land had assumed its present general shape and altitude ; it is also clear that the floods were in- fluenced in their direction by the great physical features of the country, but that at particular points they were of height and volume enough to overcome these natural obstacles. Besides the porphyritic granite of Shap, other remarkable rocks of the eastern part of the Cumbrian mountains have followed the same course. The hypersthenic and syenitic rocks of Carrock Fell, the brecciated and amygdaloidal slates of Grasmere, Ulswater, &c. may be often recognized in the same situations. Perhaps the most instructive of all examples derived from this country is that furnished by the red "brockram" of Kirkby Stephen. This member of the saliferous formation is easily known by its fragments of carboniferous limestone embedded in red sandstone, and its native site is in the depth of the vale of the Eden. From this deep repository it has been lifted by the diluvial currents over Stainmoor, and thence carried with the granites and other rocks of the Cumbrian group. The rocks in several parts of the Cumberland and Westmoreland moun- tains are scratched and grooved as by the passage of heavy bodies. This occurs on Windermere, about Kendal, and near Ulswater. The currents to which these effects are ascribed, must have flowed from the north-west. From the western part of the Cumbrian group BOULDEB DEPOSITS. 423 of mountains, currents flowing nearly from north to south have carried the granite of Ravenglass and Muncaster along the low ground west of the carboniferous chain of Yorkshire and Lancashire to the vicinity of Manchester, and through a great part of Staffordshire ; hut this sort of granite has scarcely anywhere crossed the carboniferous chain, to spread down the valleys of the Aire, Dun, Derwent, or Dove.* In this case, as in the former, it is evident that the current was directed by the great physical features of the country, which were the same then as now. In the vicinity of Ingleborough and Peny- ghent, blocks of slaty rocks have been lifted and carried several miles to the tops of limestone hills, and sometimes 200 feet higher than any part of the ranges of the slate. f From the lackey Hill. The quartz pebbles of the Lickey have been widely diffused over the plains of Warwickshire and Gloucestershire to the foot of the Cotswold hills, but on arriving at this barrier they are stopped, except at two low points, the summits of the valleys of the Cherwell and the Evenload. Down these valleys, and along their borders, the pebbles hold separate courses till the streams unite near Oxford, after which the general course of the valley of the Thames is the track of the diluvial deposits. A tendency to be arranged in narrow, longitudinal spaces is some- times observable in the diluvial accumulations. In Lincolnshire a long narrow ridge of diluvial chalk runs out in a south-westward direction by Faldingworth. In Yorkshire the lias boulders from Robin Hood's Bay keep nearly parallel to the present north and south line of coast, and extend into Norfolk and Suffolk ; and the flinty gravel from the Wolds runs north and south from Pocklington to Cave. These observations will probably be much extended hereafter. Scotland. The valley of the Forth and Clyde is filled at intervals by abundant deposits of the glacial period, filled, as those of England are, with rock masses from the north and neighbouring parts. In several districts round Glasgow, in Lanark, Renfrew, and Dumbarton, marine shells have been found in the drift, under it, and above it, and the general character of this deposit is the same as in England, the drift shells also indicating arctic analogies. J Pecten islandicus, and Cyprina islandica are among the most common of these shells. Ireland. The central area of Ireland, comparatively depressed in level, is very full of detrital deposits of the glacial era. The eastern and western counties are equally marked by such deposits. South of Dublin they spread to the foot of the mountains, and yield marine shells ; in Mayo and the country farther north, they lie in great abundance, and show clearly prevalent currents from the north, and * Glacial deposits occur in the valleys of Aire, Calder, Ac., but they may have been placed there by currents returning from the east f Phillips's Rivers and Mountains of Yorkshire, t J. Smith, in Wernerian Trans. 1839. 424 PLEISTOCENE DEPOSITS. yield examples of perched erratic blocks. On the flanks of the Mourne Mountains, on the shores of the Lakes of Killarney, and on the sloping steeps which margin the bays of Dublin and Killiney, scratched rocks indicate the movement of heavy masses over the subaqueous or subaerial surfaces. Russia in Europe. Murchison* assures us that, from the German Ocean and Hamburg on the west, to the White Sea on the east, a vast range of country, having a length of nearly 2,000 miles, and a width varying from 400 to 800 miles, is more or less covered by loose detritus, including erratic blocks of colossal size, the whole of which is derived from the Scandinavian chain. There is often to be traced a certain arrangement or method of definition in these accu- mulations ; they commonly appear in long zones, separated from each other by large breadths of depressed space clear from blocks. The accumulations are remarkable on plateaux and high grounds, and specially abundant on the southern slopes, the northern sides being often clear of detritus, and exhibiting marks of having sustained watery pressure. The rocks under and in the vicinity of these de- posits are often striated. On Lake Onega, at Salomenskikamen, striae appear on the north side of a hill, on the hill top, and below the lake surface, but not on the south side. Angular blocks some- times lie quite distinct from other boulders The detritus, speaking generally, does not follow the descent of the surface, or the course of streams ; but keeps in nearly straight courses, as for 700 or 800 miles, from Russian Lapland to Noroneje and Putievil, south and south-east of the place from which they started. The Ural chain and immediate slopes are free from detritus of this order. North America. In examining the surface of the North American continent, over a breadth of longitude of 2,000 miles, namely, from Nova Scotia, through New England, New York, the Canadas, Ohio, Michigan, Illinois, and the region west of the Lakes, nearly to the Rocky Mountains, it is certain that the general direction in which the boulders have been carried is south-easterly. The greatest part of the force by which they have been transported, has been con- fined between a south and south-east direction. This appears both by the distribution of the masses, and the scratching and furrowing of the rocks, which are recorded in very many localities, and in very striking forms. Exceptions, indeed, occur directions to the west of South, for instance on the St. Lawrence, in the western part of New York, New England, and Vermont, where furrows run S.W. or S.S.W. The boulders do not appear to radiate from particular mountain centres, but to have crossed the high ridges and deep valleys. The lines on which their dispersion is noted are approximately parallel, * See Geological Survey of Russia, chap, xx., for the following and other data, and excellent general and special reasonings. EBKATIC BLOCKS. 425 the boulders grow less and less in size as we recede from their points of origin, except that often the huge rocks are perched on rocky hills and mounds of drifted material. Boulders have been lifted from lower to higher ground, even to a thousand feet and more, as where the blocks of quartz and silurian rock lie on the highlands of New York and Jersey. Striations are remarked on slopes and hill tops, even to a height of 2,300 feet above the sea, as on Mount Everett, and other high points in the hilly region of Massachussets.* They sometimes follow the course of valleys. From the Alps The most extraordinary effects of tumultuous waters upon the surface of the land, appear sometimes to surround lofty ranges and groups of mountains. Thus the Mont Blanc group of primary mountains has been rent to pieces by some violent convulsion, and its mingled fragments transported along the lines rather than in the actual channels of the Rhone and the Arve into the Valais, along the Lake of Geneva, and up the slopes and through the valleys of the Jura even far into France. By this extraordinary course, blocks of enormous magnitude have been drifted in great numbers on to the tops of mountains, even to the height of 2,000 or 3,000 feet above the Lake of Geneva, and left there in such abundance as to encumber the land with thousands of extraneous masses. There appears in these collections of blocks a very singular tendency to association in groups and lines, (De Luc) and many striations and groovings on the rocks, under and near to the dispersed blocks, attest the force which accompanied the drift. It is particularly to be remarked that no ordinary action whatever could possibly cover the abrupt mountains of the Saleve and Mont Sion with such immense and numerous masses of these rocks, or transport them across the deep and wide valley of the Ehone to the steep slopes of the Jura. For such powerful effects it will be difficult to assign an adequate cause, and however much influence we may ascribe to the impetuosity even of an uplifted sea possibly co-operating with the disruption of glacier- covered mountains, the phenomenon must ever appear of the most remarkable kind. We seem to perceive, on a general view of the dispersion of these erratic blocks from the Alps, a remarkable relation to the existing valleys. While the Mont Blanc group has yielded fragments to the Rhone and the Arve, the Bernese Oberland has supplied the basin of the Aar and the neighbouring part of the Jura ; the valley of the Reuss has conveyed the waste of the mountains at its source ; blocks from Glaris lie by the Lake of Zurich, and the valley of the Rhine holds the rocks of the Grisons. The great range of the Jura, opposed to the Alps, and separated Hitchcock in Trans. Americ. Assoc. of Naturalists, p. 184 ; Ropers, Locke, Couthony, and other geologists, have expressed their views in the same valuable volumes. 426 PLEISTOCENE DEPOSITS. from them by the long and wide valley of the Aar prolonged into the Lake of Geneva, has furnished the best opportunity of determin- ing the geographical and other data belonging to the curious problem of the dispersion of these blocks. It is certain that in their course from the Alps the blocks have principally followed the line of the present valleys, since they are found along their sides in greatest plenty, and are collected in most abundance, and lie at the greatest heights, on those parts of the Jura chain which directly face the embouchures of the valleys. Yet this relation to the valleys is of such a kind, that the blocks, instead of being limited to their beds, lie perhaps more plentifully on the hill sides, and intimate a totally different kind of watery action from that of the running streams. One of the grandest examples of the force and continuity of diluvial currents is the dispersion to the southward, across the Baltic, of the primary and transition rocks of Sweden and Norway. Brongniart (Tableau des Terrains) has given an excellent view of these phenomena. From Scandinavia. The sandy plains of Westphalia, Hanover, Holstein, Zealand, Mecklenburg, Brandenburg, the coasts and plains of Pomerania, Prussia, and part of Poland far inland between Warsaw and Grodno, and consequently all the low, generally flat and sandy countries which border the Baltic and German Ocean from the Ems and the Weser to the Dwina, and even the Neva, are covered at intervals by these blocks. They are not uniformly dispersed, but collected in particular spaces, and form in the midst of these vast sandy wastes distinct groups, generally elliptical in outline, with the longer axis directed north and south, or toward the Baltic Sea. Bruckner mentions a trainee of these blocks in the northern part of Mecklenburg-Strelitz, which runs from west north-west to east south- east. They are more abundant on hills than in valleys. The largest blocks are most superficial and nearest the tops of the hills. They consist of granites, syenites, silurian limestone with trilobites, &c., and other rocks which have the greatest resemblance to the rocks of Sweden ; they contain the same peculiar minerals, and the same peculiar organic remains. Their course from the Scandinavian penin- sula is generally from north-east to south-west. On approaching the mountains whence they were dislodged, we find the number of the blocks to increase considerably, and on crossing the Sound to Scania, they appear at every step, but the size of the blocks is not greater. The mountains of Sweden are not more burdened bj r loose blocks than is common to such tracts, but the faces of the rocks there appear furrowed and rubbed by the drifting of heavy bodies southward. The Baltic Sea, which crosses the line of these trainees of rocks, appears to have interposed no obstacle to their movement, since the heaps of blocks lie in the same direction on both sides of the water, and the quantities carried over are immense. GEAVEL DEPOSITS. 427 Some of the granitic boulders on the coasts of Yorkshire and Nor- folk are thought to have come from the same Scandinavian moun- tains. From observations in England, Dr. Buckland inferred that the general direction of the diluvial currents was from the north-west. In North America, Dr. Bigsby and other observers have observed the prevalent direction to be from the north-west or north-east. The Scandinavian blocks have travelled over a tract widening to the southward. But the waste of the Alps has gone nearly as the valleys run, in all directions ; southward to Italy, westward to France, north- ward to the Rhine, and generally we may be assured that the preva- lent direction in any country has a very close relation to the physical geography of the region near the origin of the boulders. The degree of attrition of the erratic blocks is various, and gene- rally not so considerable as that of the smaller pebbles which compose the greater part of the diluvial masses. The great blocks are fre- quently found on the tops of the hills composed of gravel and clay. inferences. From the preceding data we are warranted in con- cluding that since the deposition of all or nearly all the marine strata which are seen in our continents, and since the actual land was up- lifted from the sea, and shaped into its present leading physical features, large parts of the earth's northern surface have been deluged by floods passing in various directions, which removed large quanti- ties of the preconsolidated rocks, and dispersed them over distant countries, in such abundance, of such magnitude, to such distances, in such directions, and to such altitudes, as to preclude the possibility of explaining the phenomenon by the action of actual streams, flow- ing in the ordinary course of nature, or deviating in any possible manner over the surface of the earth, or by the bursting of lakes, how- ever situated or circumstanced. For neither streams nor bursting lakes could possibly transport the Shap Fell granite to Flamborough Head, nor drive the syenites of Sweden into the heart of Poland. Gravel Deposits. For the sake of exhibiting decided proofs of the powerful action of the diluvial waters, we have insisted much on the transport of large blocks of recognizable rocks ; but it must not be imagined that blocks of such magnitude compose the whole or the greater part of the diluvial deposits. These consist, in fact, of the detritus and fragments of every sort of rock, and of all sizes, from the giant blocks on the Jura to the finest sand and sediment. The eastern coasts of England, in Essex, Norfolk, and Yorkshire, are principally occupied by diluvial cliffs of clay, with interspersed pebbles and blocks, and irregular layers of gravel and sand. These deposits cover large tracts in Yorkshire, Lincolnshire, Norfolk, Suf- folk, Essex, &c. In the Midland counties, gravel, containing in some places abundance of chalk flints, and in other situations pebbles from the Lickey Hill, is very common, and in particular valleys quantities 428 PLEISTOCENE DEPOSITS. of oolitic gravel. It is generally observable that tbe most abundant por- tions of the deposits may be traced to the neighbouring ranges of hills, as the chalk of Holderness, Faldingworth, and Huntingdon, to the neighbouring wolds, the sandstones of the vale of York to the Western moorlands, and the quartz pebbles of Warwickshire to the Lickey Hill, but with them generally lie fragments from more distant sources. In these gravelly deposits we not unfrequently find many marine shells, often littoral shells, and thus acquire a power of inferring the least depth at which the ocean stood upon the land. One of the best known cases is that brought forward by Trimmer, who, by examinations of Moel Tryfan, in North Wales, discovered littoral shells in drift about 1,500 feet above the actual sea level. This may be regarded as a fair general measure of the former elevation of the sea, or as all geologists now prefer to phrase it, the former depression of the land during the period of boulder dispersion. To this same height the distribution of blocks in Craven, and over Stainmoor in Yorkshire, and the parallel roads of Glen Roy, appear to conduct us. It is not necessary to suppose a greater, probably not so great a submersion for the lands in European Russia ; but a greater depth is claimed for the depression in North America. Theory. In any attempt to connect the results by theoretical bonds, we must take into account several classes of phenomena which only long-continued attention has brought together in a form suited to the inductive philosophy. 1. The deposits are marine ; they contain sea shells ; they show in- some parts local agitation such as belongs to shallow seas ; in others, a confused aggregation, not to be so explained, and often are capped by blocks so vast as to defy explanation by any conceivable action of water. 2. The physical features of the country over which the detrital masses passed, were nearly as they are now; but large regions being submerged, it is clear that these physical features have had little effect in directing the main flow of cur- rents, though some such influence can be traced on modifying the amount and arrangement of deposits. 3. The most general directions yet traced are from north to south, or from north-west to south-east in which directions, seas as well as valleys have been crossed. 4. If watery forces may be supposed to be generated by violent convulsions, adequate to transport the huge blocks of rock, sometimes observed, these forces soon weakened by proceeding from their source, must further be supposed to be renewed from point to point, even when the slope of ground is favourable, and fail entirely, even with this help, to explain the drifting for hundreds of miles, across hills and valleys, and broad tracts of ocean. 5. For these cases, an obvious, and apparently adequate power, is recognized in modern icebergs, which, broken off from glaciers, at the edge of the sea, and bearing away whatever rocky materials may have fallen on those streams of ice, are delivered to the sea currents, and transported by them into lower latitudes and warmer climates, to melt, founder, or be overturned, and. in either case, to drop their far-travelled rocks and finer matters on the bed of a distant sea. Thus annually travel southward into the Atlantic the icebergs from the northern seas, and others northward from Victoria Land. In the former case, they melt GLACIAL DEPOSITS THEORY OF. away, for the most part, in solitary masses, in the deeper parts of the Atlantic ; in the latter example they congregate, in great numbers, along a zone of the sea 700 miles from their source, and there make a collected, and, probably, very large deposit, like the Osar of Norway, and Escars of Ireland. Such materials" would be, in the main, a very confused mass; but yet, as the depth of the ocean varied, at first shallow, then greatly deepened, and finally reduced to nothing as the land rose again, the ordinary action of moving water must appear in them more or less. Shells appear in them, and it is curious to notice in these, among the drift masses of the northern zones, the only contemporary witnesses of the operations, a certain arctic character, suited to the probabilities of the case. 6. But, further, we find, on the most careful study, reason to think these icebergs, partially arrested in shallow water, and dragging on the sea bed, where that was covered with gravel, might so press on the rocks below, and so urge the grinding of them by the movement of the gravel, as to scratch, and groove, and polish them. This appeared probable to Lyell, and was confirmed by Murchison after his study of Russia. Rogers and Hitchcock, after considering the worn lime- 1 stones, gneiss, and other rocks of North America, and examining largely the whole subject, ascribe a great proportion of the drift phenomena to the same cause. Miller believes in the same agency for Scotland: it appears to us appli- cable to the phenomena over a great part of England and the borders of Wales. 7. Icebergs are not formed except at the edge of ice-covered land: they float away in masses of incredible size even half, or two-thirds of a mile in length (American Naturalist's Transactions) and sink into the sea 1,000, 1,500, or 2,000 feet! Tracing back the erratic blocks to their source the track of the iceberg we arrive at mountain summits like the Snowdonian range, the Cumbrian moun- tains, the Grampian range, the Alpine peaks, and the Scandinavian Fields. These tracts, then, were covered with glaciers down to the level of the sea, and, perhaps, to some considerable depth in it as in Spitzbergen the slowly, but perpetually descending streams of ice, carried on their surface, trainees of rocks, and at their extremity ploughed up the sea bed, leaving subaqueous moraines there, to be redistributed by the sea, according as the vertical movement of the' land brought them under its influence. The sea round them was chilled by icebergs, drifting southward with return currents from the north ; arctic shells- appeared in the sea. Floating and melting, through enormous periods of time, the ice-rafts overturned, deposited, and sometimes mingled their spoils; and often dragged and agitated those of earlier date, and left them in forms to which no other explanation applies. 8. In order to account for the prevalent direction to the south, recognized in the boulder deposits and the structures of the rocks, we must suppose some consider- able local displacements, or some general changes of level in the northern zones, by which the reciprocal currents from the equator and the arctic basin may have been turned quite into different channels from those which they now occupy. Such an hypothesis is required by the arctic shells in the old sea: it is equally required by the prevalence of glaciers on the northern lands ; how these lands should be covered with glaciers, while, as the other phenomena prove, they were certainly at a lower level than now, and more completely bathed in the sea, is to be considered hereafter. 9. These inferences have then* application from the Uralian chain to the Rocky Mountains, through half the circle of the 60th and 50th degree of latitude, and reach southward as far as the 40th. We must regard all this area, and pro- bably large tracts beyond, as subject to the great vertical movements alluded to ; it may not be necessary to suppose a strictly simultaneous depression of all that area, still less to regard it as a convulsive, sudden, or cataclysmal character, but it can only be viewed as one great operation, connected with one great physi- cal cause, operating through one long geological period. 430 PLEISTOCENE DEPOSITS. Postglacial Deposits. Continuing our survey of Pleistocene deposits, we next behold the glacial sea bed uplifted, and the former relative levels of land and sea restored, or nearly so ; for, in fact, many cases appear to show that the level of the land was somewhat more than regained. The cases of postglacial accumulations are to be considered chiefly with reference to the evidence they give of the state of the land : and this evidence consists in the remains of terrestrial animals and plants buried for the most part in lacustrine and fluviatile sedi- ments. The marine postglacial phenomena are, obviously, for the most part, beyond our reach, covered by the waters of the actual ocean. In the low district of Holderness, in East Yorkshire, the glacial sea bed is found elevated, and appears in ground about 160 feet, at a maximum, above the sea. The surface is very unequal, and ex- hibits a winding and complicated variety of levels, probably due, in parts, to the original irregularity of glacial deposits, but also to the action of waves upon them as they rose through the sea. In these hollows we find many lacustrine deposits of limited extent, and of extremely various elevations above the sea. They are sometimes detected under the sea level, a fact on which probably we found the best evidence for the partial subsidence of land during the post- glacial era. The lacustrine deposits alluded to, have frequently shell marl or a coarser clay as their bed ; over this peat layers and the surface soil if any. There is sometimes more than one succes- sion of the peat and marls. If all the varieties which I have ob- served at different places existed together, the sections would be nearly as under : 7. Clay, generally of blue colour and fine texture. 6. Peat, with various roots and plants, and in large deposits, abundance of trees, nuts, horns of deer, bones of oxen, &c. *5. Clay of different colours, with fresh water limnaeae. 4. Peat as above. 3. Clay, with fresh water cyclades, and blue phosphate of iron. *2. Shaly curled bituminous clay. *1. Sandy coarse laminated clay, filling hollows in the diluvium. The most constant beds appear to be 1, 2, and 5. The peat varies in thickness from five feet to a few inches. The most re- markable fossil animal in the marls under peat is the Irish elk. No case is known of elephant, hippopotamus, rhinoceros, felis, or hysena in these deposits. Lancashire, in the northern parts about Silverdale, Garstang, and other parts, discloses similar phenomena. Ireland produces them in abundance, the remains of the great elk being there almost ex- ORGANIC REMAINS. 431 clusively found in such deposits the bones of this animal being commonly found in shell marl under peat, or partly in the marl and partly in the peat. The bones in peat are tanned brown. The Isle of Man, the Isle of Arran, and many other localities, give similar results, which it is unnecessary to particularize since, by easy steps, they conduct us to the pre-historical and modern deposits of rivers and lakes, and are in fact only the earlier terms of the same series. Organic Remains of the Pleistocene Period. Animal Population at the time. The land over which the glacial currents flowed was inhabited, and very extensively so, in many districts wasted by these floods. This is evident from the really immense quantity and variety of bones of quadrupeds lying in gravel pits, clay cliffs, and other diluvial accumulations, or buried in caverns during and previous to that period of convulsion. To mention all the known localities for diluvial masses from which bones of elephant, rhinoceros, horse, ox, deer, and a variety of other quadrupeds have been obtained, would be to form a gazetteer of Europe, Siberia, and North America. There is hardly a county in England where some remains of this kind have not been obtained at many places, and they are equally abundant in France, Germany, Italy, Eussia in Europe, North Asia, &c. Exactly as at the present day the bed of a river envelops the shells that perish in the waters, with the bones of animals accidentally lodged there, so the pleistocene floods buried in the detritus of the land remains of the then existing organized creation. These remains enable us to say what races of animals were living upon the earth at and previous to the time when those parts of it were over- whelmed ; and if upon examination it be found that these animals were of peculiar types of conformation, that they did not begin to exist till a certain epoch, nor continue to live after another epoch, the period of their existence is a zoological era as distinct as any other disclosed to us by examination into the long series of periods during which organic beings have existed upon the earth. inference. In illustrating this magnificent subject from the mate- rials furnished by the researches of Cuvier and Buckland, we shall first present the evidence furnished by diluvial gravel, clay, sand, and other unquestionable deposits of the turbulent era alluded to, and afterwards add some results deducible from examination of caverns, the period of the occupation of which will be naturally determined by comparing their zoological contents with those of gravel pits, &c. " The following are some of the mammalia that have been discovered in these diluvial and preglacial deposits : 432 PLEISTOCENE DEPOSITS. PACHYDERMATA. Elephas primigenius, Mastodon augustidens, &c., Hippopotamus major, Choeropotamus, Rhinoceros tichorhinus, &c., Tapir giganteus, Sus fossilis. SOLIPEDA. Equus fossilis. RUMINASTIA. Cervus megaceros, &c., Bos, Urus, Mericotherium Sibericum. CARNIVORA. Felis spelaea, &c., Hyaena spelaea, &c., Wolf, Vulpes speluncarum, Machairodus cultridens, Ursus spelaeus. RODENTIA. Porcupine, Beaver, Arvicola. EDENTATA Megalonyx, Megatherium, two species, Manis giganteus. Mostly congenerous with those now living. The most striking gen- eral inference derivable from inspection of the preceding and more extended lists, as contrasted with all the catalogues of the earlier animals, is the almost complete identity of the genera with some of those which now exist. Even in the tertiary system, though the quadrupedal population of Europe had become considerable, and the circumstances of their existence in several respects closely analogous to what obtain at present, the genera were for the most part wholly different. Here they are for the most part the same. The species, however, of the zoological era under consideration were mostly different from the existing races, some of greater mag- nitude, others of different proportions, all distinguishable by more or less remarkable peculiarities of their bony remains. These distinctions are often minute, and to those who estimate largely the amount of possible change induced on the animal frame by long time and varying circumstances, it may perhaps be conceded to preserve a slight doubt whether the distinctions alluded to be absolutely and always character- istic of the species of animals, or be modifications suited to the circum- stances of their existence. However, for all the purposes of geological induction, the distinctions being constant are assumed to be specific, and in most cases we believe them to be so. Among the species found in caves, fissures, and breccia, referred to the same era, are the following : PACHYDERMATA. Elephas primigenius, &c., Hippopotamus major, Rhinoceros tichorhinus, &c., Choeropotamus, Sus fossilis. SOLIPEDA. Equus fossilis. RUMINANTIA. Cervus megaceros, &c., Bos, Urus, Antilope. CARNIVORA. Felis spelaea, &c., Hyaena spelaea, &c., Polecat, Weasel, Gulo spelaeus, Wolf, Fox, Ursus spelaeus, Ursus cultridens, &c. RODENTIA. Arvicola fossilis media, Arvicola fossilis minor, Rat, Lagomys, &c., Hare, Rabbit, &c., Beaver. From the general analogy between these two lists, from the pre- valence in each of elephants, rhinoceros, hippopotamus, felis, hyaena, and bears, in countries where at present not a single animal of such genera is known to exist, there seems very good reason to admit them as belonging to the same zoological era, which M. Omalius D'Halloy has, not inconveniently, called the mastozootic era. But all investigations concerning gravel and other diluvial deposits prove ELEPHANTOIDAL EEA. 433 indubitably that this era is exactly that which ended with the dilu- vial system of deposits. We may, therefore, venture in the following investigations to class together the remains of mammalia found in caves, fissures, breccia, gravel, clay, &c., as characteristic of a period of some duration, terminated in each district by great inundations, and equally capable of furnishing evidence concerning the then state of the earth. It is not meant by this arrangement to pronounce at all concerning the question, yet very insufficiently examined, of the partial contemporaneity of the palseotherian and mastozootic races of animals in Europe. Lived in Countries where their Bones are found. The first general result which we shall venture to draw from this combined evidence is, that the animals whose remains are found in diluvial gravel and other superficial accumulations, or in limestone caves and fissures, or in ferruginous breccia, lived near or on the spots where their bones are found. This important inference might be safely deduced from the ordinary circumstances under which fossil bones are found in superficial gravel, &c. ; since in these cases they are little worn, though lying amongst fragments of rocks rounded to pebbles, and often remain entire, or with no other injury than that occasioned by the effects of the atmosphere. Thus the horns of a stag, scarcely in the smallest degree injured, have been obtained from the diluvium of the vale of Pickering, the long tusks of an elephant from that of Holderness and Essex. This conclusion might, perhaps, with equal certainty be rested upon the occasional finding of the bones of ele- phants and rhinoceros, and other " antediluvian" species, in marl pits under gravel, in company with shells now existing in the neigh- bourhood, of which some indications occur in Cuvier's celebrated work, the Ossemens Fossiles, and a more distinct case has been re- corded at Market Weighton in Yorkshire. For in this case the bones of extinct and the shells of existing species of animals lay pellmell together, and the native locality of one must inevitably be ascribed to the other. But the case becomes certainly stronger, when we take into view the history of the caverns, fissures, and breccia, containing bones ; for these afford us not only reason to conclude that certain animals lived in definite regions at a particular era, but display many of their habits of life and accidents to which the nature of the country exposed them. Climate of the Northern Regions in the Elephantoidal Era. As no doubt whatever remains that in the " diluvial" period, and for a long time previous, there existed in Europe elephants, rhinoceros, hippopotamus, lions, and hyaenas, besides bears, the glutton, wolves, foxes, the horse, oxen, the urus, deer, beavers, hares, rabbits, water- rats, &c., we are presented with a problem of considerable interest 434 PLEISTOCENE DEPOSITS. relating to the state of the climate at that period. The most abun- dant, perhaps, and most generally diffused of all these remains are those of the elephant and rhinoceros ; though in particular cases bears or hyaenas fill whole caves, and the horse, ox, and urus are very plentiful in gravel and marl. So many animal remains of genera now exclusively confined to hot climates have induced many geolo- gists to conclude that the northern regions of the globe were at that time much hotter, and that their total extinction was occasioned by a sudden refrigeration of the climate. On the other hand, the glut- ton, the urus, wolves, foxes, bears, horses, and large horned deer, and beavers, appear as characteristic of cold or temperate climates, and furnish arguments for the doctrine that the animals resembling those now living in tropical regions were fitted by some peculiarity of con- stitution to support the rigours of the northern zone. These state- ments are so equally balanced, and the authors who support them so respectable, that no impartial inquirer can pronounce between them without further evidence. This evidence must be of a parti- cular kind. It will be of little use to add to the number of animals on either list ; and as the species are different from those now in existence, the relative power of adaptation to climate of their several living analogues will not be sufficient to settle the point. We must find the remains of some of these animals in such condition, or accom- panied by such collateral circumstances, as to characterize the climate independently of the generic relations of the animals. Evidence on chis subject. Two cases coming within these condi- tions are known to geologists, of so distinct a kind, and leading so positively to the same conclusion, as to leave little room for further discussion. The first is the instance of an elephant, of the same species precisely as that usual in diluvial accumulations, being found in 1804, enclosed in solid ice, at the mouth of the Lena, where that Siberian river flows into the Arctic Sea. It was a perfect animal, with tusks in the jaws, and had evidently been entombed in its icy sepulchre immediately after death, for the flesh of its huge body was not decayed, but actually furnished a feast to the wolves and bears of the coast ; the skin remained entire, and its whole surface was covered with hair of two kinds, one shorter and finer near the body, the other coarse and bristly, and even sixteen inches long. It is to be regretted that the difficult circumstances of the country did not permit Mr. Adams to examine minutely the anatomy of this specimen, thus wonderfully preserved through the fluctuations of ages ; but the skeleton, mounted at St. Petersburg, furnishes sufficient characters to prove its perfect agreement with the fossil, and its distinctness from either of the living elephants. Here then is a plain proof that the fossil elephant was fitted, by an appropriate clothing, to withstand the occasional cold of a high northern latitude, GEOLOGICAL EXISTENCE OP MAN. 435 not perhaps to exist on the shores of the icy sea, but to inhabit about the sources of the Siberian rivers, and over the whole extent of Europe and a part of North America. The north coast of America, as well as that of Siberia, encloses abundance of the remains of these elephants in cliffs of frozen mud. (Captain Beechey.) The conclusion from this fact is rendered still more decisive by the discovery, in 1770, of the fossil rhinoceros tichorhinus, under the same extraordinary circumstances of preservation of flesh, on the banks of the Wiluji, which falls into the Lena below Jakoutsk, and its body was likewise covered with hair. Dr. Buckland's conclusion of some remarkable catastrophe and sudden refrigeration of the Siberian regions and the borders of North America, near Behring's Straits, seems to offer a reasonable explanation of the extraordinary preservation of these remains, which besides may have been drifted from their original seats northwards. The second case is the discovery together in the same marl pit connected with gravel deposits, near Market Weighton, in Yorkshire, of the remains of elephant, rhinoceros, lion, wolf, horse, urus, ox, deer, &c., species all or nearly all extinct, with thirteen species of land, marsh, and fresh water shells now living in the neighbourhood. Now, as hardly any animals are more remarkably limited in climate, and restrained by local circumstances, than the molluscous tribes of the land and fresh waters, as the number of the species here dis- covered is considerable, and their identity altogether certain, without a single extraneous species, it is a safe conclusion, that the climate in which they lived was that which England and the central parts of Europe now enjoy ; for such mollusca become mixed with other races on approaching the Mediterranean, and many of them cease to exist in the colder latitudes of northern Europe. The same conclusion results from the examination of that remarkable deposit called " Loess," in the valley of the Ehine, where the extinct elephants and rhinoceros He with many existing land shells. (Horner.) Hence we conclude, with confidence, that the antediluvian ch'mate of the northern parts of the globe was nearly the same that it is at pre- sent ; and it is no great objection to this view, that the banks of the Frozen sea will not now feed an elephant, because, in the first place, it is not yet proved that the elephants were not drifted by the long Siberian rivers to their frozen mouths ; and secondly, our conclusion is for a temperate or cold, not frigid climate, as distinguished from the torrid climate, to which some geologists would unmercifully subject these animals in their warm winter dress. Geological Monuments of the Existence of Man. In all the periods of time which elapsed during the formation of the stratified rocks, there is no evidence that man was a dweller on this globe. Not in the most recent of the eocene strata, neither in the littoral nor in 436 PLEISTQCETsTJ DEPOSITS. the lacustrine deposits of that period, have any traces of man or his works been perceived. This ought in no degree to surprise us, for all the animals and plants of that and earlier periods were parts of an earlier system of organized nature. But it appears something extra- ordinary that bones of men and vestiges of human art should have been so rarely found in any of the ascertained deposits of the diluvial era, except under dubious or explanatory circumstances, since at that time the earth had assumed its present form and appearance, and was inhabited by races of quadrupeds which, if not specifically the same, were, for the most part, closely analogous to those which now live ; in particular, the horse and domestic cattle, animals so singularly serviceable to and dependent on man, existed in great plenty in the northern zones, and, therefore, the present system of organized nature, of which man is the head, may be said to have commenced. That the bones of men are as durable as those of quadrupeds, is established by comparisons made on fields of battle, and, therefore, if he lived with the mastozootic quadrupeds, his remains should, under some circumstances or other, be found mixed with theirs. Dragged into a den by the prowling hysena, or accidentally lost in a fissure, or overwhelmed by waves and buried in diluvium, we should occasionally meet with the bones of our ancestors. Old writers, who saw in everything only the traces of a general deluge, are full of dis- coveries of the bones of men ; but modern anatomy has assigned them to their true analogies, the elephant, salamander, and saurian. In modern times a few examples of bones of men, found under circum- stances arguing great antiquity, have been recorded. Upon strict examination it appears that in most cases these remains belong to a later epoch than the diluvial convulsions : the petrified bodies of the coast of Gruadaloupe are enveloped in comparatively recent accretions ; the human remains of the valley of the Elster, near Leipzig, appear to have been inhumed since the general dispersion of diluvium ; the woman found in Paviland cave was of an early British era. The only cases remaining for further examination are some caves in the south of France, where the remains of man and rude pottery are found mixed with a quantity of bones belonging to extinct species of animals of the mastozootic era ; superficial deposits in Baden and in Austria, where remains of men with depressed skulls (as if occa- sioned by unnatural bandages) are found ; and the remarkable notices by Boue of mingled human and animal remains in the breccia of Nice and Dalmatia. in South of France. Without stopping to discuss the yet imper- fect evidence concerning the antiquity of these remains in the breccia and superficial accumulations, we shall pass to the consideration of the caves in the south of France. From, the examinations of Tour- nal, Christol, and Marcel de Serres, a considerable body of evidence CAVES IX SOUTH OF FRANCE. 437 has been collected concerning the caverns of Bize, (Aude,) Durfort, Pondres, Souvignargues, (Gard,) and from the similar state of con- servation as well as mixture of the bones of men and animals in the caverns of Bize, M. Tournal decides positively that their age is the same. These animals are stag, chamois, roebuck, antelope, and bear, which hardly require to be considered of the mastozootic era. The same conclusion was drawn by M. Christol, from subsequent researches in the caverns of Gard, in which the animal remains were decidedly of the same era as the fossil elephant and rhinoceros. But the most instructive, probably, of all these discoveries, is that of the cavern of Miallet, near Anduze, (Gard,) completely investigated by M. Teissier. This grotto, situated on the banks of the Garden, is opened in a dolomitic rock subordinate to the lias, on a steep slope, thirty metres above the valley. The lower layer of the interior of the grotto is dolomitic sand, irregularly overspread by a thin stalagmitic crust, and in places by an argillo-ferruginous mud, more than a metre thick, and adhering in several places to the roof and sides. In this bed were discovered in great abundance, and excellent preservation, bones and teeth of large bears, and with them a few bones of hyaena, ruminantia, and birds ; under the stalagmite, and under a bed of loamy sand from two to four decimetres, a great number of human remains was found in various parts of the grotto. In the depth of the cavern they are unquestionably mixed with the bones of bears, which predominate ; towards the entrance, on the contrary, human remains are most abundant, and appear of less antiquity. Upon the ossiferous loam, under a little projection of rock, was discovered a human skeleton nearly entire, near it a lamp and small figure in earthenware ; farther off bracelets of copper ; in other situations coarse pottery, wrought bones, and edge tools of flint, indicative of ruder industry. The human skulls were depressed from above, ap- parently by artificial means, thus presenting a deceptive resemblance to the negro, though really belonging to the Caucasian race of men. M. Teissier infers from these data that the accumulation of dis- tinct periods can be traced in this cave : 1. The mastozootic or antediluvian era of the bears, with whose remains those of men are mixed, perhaps by subsequent natural or artificial means. 2. The era of rude civilization (probably Celtic,) when the coarse pottery, Hint tools, &c. were introduced, perhaps, to grace the sepulture of individuals. 3. The era of Roman arts. There is no necessity for hazarding a definite conclusion on the antiquity of these human remains, because there is very great proba- bility of gathering much additional information by the discovery of new caves under different circumstances. In the meantime we may remark that the principal arguments for the coeval existence of men, and extinct pachydermata and carnivora in the south of France, is the 438 PLEISTOCENE DEPOSITS. intimate mixture and equal conservation of the bones ; and these argu- ments should not be slighted, for they would, probably, not have been resisted in any case of the mixture of quadrupedal remains. On the other hand, the known facts that parts of the Mediter- ranean shores were anciently possessed by Troglodytic nations, and that the custom of burying in caves, as well as retiring to them for safety, was very general in these countries, adds great force to the opinion of M. Desnoyers, that, in most cases, the human remains are of no greater antiquity than the early Celtic ages, in which similar works of art were executed. (See Desnoyers, Rapport a la Soc. Geol. de la France, 1831.) It is clear that ossiferous caves have received their contents, some at one period, and some at another, and that in others operations of the same kind, repeated at very different periods, have consigned to our investigation monuments of all the great zoological changes which have happened on the dry land, since it first became tenanted by mammalia. The whole subject must yet receive a great accession of well-observed facts. One remark, concerning the excessive rarity or non-existence of human remains in diluvium, and in caves of the elephantoidal era, may be of considerable importance. Those parts of the earth's surface to which traditions and, perhaps, general rea- soning, seem to point as the first sites of the human race, the central regions of Asia, have been as yet little examined with reference to this question. It may be very possible yet to discover them there even in abundance, though in the high northern regions men may not have existed till much later periods. It is a singular fact that the Quadrumana or monkey tribes, which so nearly approach to the bodily organization of man, are almost equally absent from the deposits of which we are speaking. Upon the whole, the evidence yet obtained concerning the geolo- gical period when the human race began to exist on the globe, is very imperfect, and we may, perhaps, wait long for more full infor- mation. In the meantime, it may be stated as a general admission, that man did not exist on the globe during the secondary, and, pro- bably, not during the epoch of eocene and pleiocene formations, and that sufficient evidence for his coexistence in Northern climes with the mammoths and hippopotami is yet wanting ; but as the races of oxen, horses, camels, &c., had then begun to exist, it is not, perhaps, an unreasonable expectation that, eventually, this question will be decided in the affirmative. OEG ATTIC BEMAItfS. 439 GENERA OF PLEISTOCENE BRITISH FOSSILS. PLANTS. Filicites, . Chara, Pinus, Strobilites, Taxoxylon, Alnites, Ceratophyllum, Rhamnites, AMORPHOZOA. Halichondria, FORAMINIFERA. Rosalina, . ZOOPHYTA. Sertularia, . Balanophyllia, Millepora, . ANNELIDA. Spirorbis, . CIRRIPEDIA. Balanus, . ENTOMOSTRACA. Bairdia, Candona, . Cypris, Cythere, . BRYOZOA. Tubulipora, BRACHIOPODA. Discina, MONOMYARIA, Anomia, Ostrea, Pecten, DIMYARIA. Anodonta, . Area, . Artemis, . Astarte, Cardium, Corbula, Cyclas, Cyprina, . Cyrena, Lucina, cies. Mactra, 1 Modiola, ; 2 Mya, 2 Nucula, 1 Panopaea, . 1 PectunculuSj 1 Pholas, 1 Saxicava, . 3 Scrobicularia, Solen, Syndesmya, I Tellina, Thracia, 1 Unio, Venus, 1 GASTEROPODA. 1 Achatina, . 1 Auricula, . Ancylus, 2 Assiminia, . Azeca, Balsea, 3 Buccinum, . Bulimus, Bulla, 1 Carychium, Cemoria, 5 Clausilia, . 1 Cyclostoma^ Dentalium, 1 Fusus, Helix, Limax, 1 Limnsea, Littorina, . 4 Margarita, 1 Nassa, 3 Natica, Paludina, . Patella, 1 Phasianella, 1 Physa, 1 Planorbis, . 5 Pupa, 3 Rissoa, 1 Succinea, . 6 Trochus, . 1 Turritella, . 2 Valvata, . 1 Velutina, . No. of Species. 1 1 1 1 1 2 1 .. 1 3 1 4 1 4 5 1 1 2 1 1 1 2 3 1 1 1 4 1 1 g 24 1 5 2 1 3 3 3 3 1 2 9 9 7 3 1 1 3 2 440 PLEISTOCENE DEPOSITS. BIRDS. Anas, Alauda, . Columba, . Corvus, Perdix, MAMMALIA. PACHYDERMATA. Elephas, Hippopotamus, Rhinoceros, Sus, . SOLIPEDIA. Equus, Asinus, RUMINANTIA. Urus, Bos, Capra, Cervus, Megaceros, . Strongyloceros, RODENTIA. Arvicola, . Lagomys, . Lepus, No. of Species. Urus, , 1 Sorex, . 1 Trogontherium, 1 CARNIVORA. ".; , 1 Canis, * -L Felis, Hyaena, Machairodus, 1 Meles, 1 Putorius, . 2 Ursus, . 1 Vulpes, . CETACEA. o Balaena, * 2 I Balaenoptera, JL Monodon, . Phocaena, . . 2 Physeter, . 2 QUADRUMANA. 5 Macacus, . 1 INSECnVORA. . 1 Paleospalax, Talpa, , 3 CHEIROPTERA. 1 Rhinolophus, - 2 Vespertilio, No. of Species. 1 3 1 2 . . 4 . . 1 2 . 1 2 3 1 1 1 1 1 1 340 Skeleton of Megatherium, Paraguay. OEGANIC EEMAINS. 441 342 Skeleton of the Irish Elk. 442 PLEISTOCENE DEPOSITS. TABLE OF REMAINS OF MAMMALIA IN CAVERNS AND SUPERFICIAL DEPOSITS OF THE PLEISTOCENE PERIOD GENERALLY. N.B. Extinct genera are marked with an asterisk. Caverns marked with c. Breccia with b. Name. In caverns and breccia of all ages. In diluvial and earlier accumulations. ( c. Gailenreuth, Zahnloch, Pavi-) KKllMt .- phinpValw Anotri^ Remains of men .......... ! land, Bize, Durfort, Pondres, V Ko ? iz ^ Rhme valley, Austria. (. Souvignargues, Sicily ........ ) 6. Nice, Dalmatia. Vespertilio ................. c. Franconia, France ............ Kostritz. 6. Cagliari, Antibes. Sorex ...................... c. Avison. 6. Sardinia, Dalmatia ............. Ditto. Talpa ...................... c. Avison ........................ Ditto. Ursus spelaeus, Blum ....... c. Germany, France, England. . > , ...,,.._ 6. Krain, near Krembs, Munsterf Chatillon. arctoideus, Blum. ..... c ' onia ' Bize ' Sallfele8> Lunel otherspecies .......... Machairodus cultridens, Cuv. c. Sundwich, Kent's Hole ............ Val' d'Arno, Puy de Dome. 6. Perpignan .................... Puy de Dome. Nasua, Cuv. ................ ft.Nice Meles vulgaris .............. b. Lunel Vieil, Salleles. Gulo spelseus ............... c. Gailenreuth, Sundwich. Viverra, Clift ............... c. and b. Australia. CanisspeUeus,(Wolf.)....{ fc SS^..^?...??!!^} Yorkshire. 6. Sardinia. famUiaris (dog) ......... c. Lunel Vieil. other species ........... c. Franconia, Bize, Salleles ....... Val ' d'Arno, Avaray. Vulpes vulgaris ? ............ 6. Sardinia ; c. Kirkdale .......... Perrierburg. ( c.Kirkdale,Plymouth, Swansea, 1 Paviland, Muggendorf, Harz, Kostritz, Canstadt, Eichstadt, Fouvent, Sundwich, Lunel \ Val' d'Arno, Herzburg, Ab- Vieil, Pondres, Kent's Hole, beville, Lawford. other species, Goldf. .. -j ^^SK Puy de Dome, Velay. ( c. Kirkdale, Plymouth, Gailen-l K - K . f _. f _ Va v fl'Amn rcu.i Felis spetea, Goldf ....... \ reuth, Baumann's Hohle, J ^"t 2 '. ^al d Arno, Biel- 1 Sundwich, Lunel Vieil ....... J becks m Yorkshire. antiqua, Cuv. ... ........ c. Gailenreuth ; 6. Nice. other species ........................................... Upper Italy, Puy deDome. Mustela (polecat) ........... c. Lunel Vieil, Gailenreuth ...... (weasel) ................. c. Kirkdale ...................... Lutra antiqua, M. de S ...... c. LunelVieil ................... otherspecies ............................................. Puy deDome. Dasyurus, Hypsiprymnus. . "J Castor ...................... c. LunelVieil ................... Val 1 d'Arno, Puy de Dome. * T TF?sch e ) ri " m ... C ^ U .l ................................ Taganrog, near the Sea of Azof. Werneri, Cuv ........................................... Jaroslav. * ( S Ha rian) ..^^f!?} ................................ Near the Delaware. Mns "( c. Kirkdale, Salleles ............ > Lawford Mus ...................... | b. Gibraltar, Sardinia .......... f Lawford. f c. Kirkdale, Gailenreuth, Sund- Arvicola ................... 1 wich, Gibraltar, Nice, Cette, ( Corsica, Sardinia. Hystrix .................................................... Val' d'Arno. Lepus diluvianus and) *J^ 2~ S Puy de Dome. others .................. 6. Cette. Corsica, Nice ......... j Lagomys corsicanus, Brurdet d. Sardinia, Gibraltar, Cette, Nice. Chloromys .................................................. Ditto. ORGANIC REMAINS OF THE PLEISTOCEKE PERIOD. 443 Name. In caverns and breccia of all ages. In diluvial and earlier accumulations. *Megatherium Cuvierii ...................................... North and South America. *Megalonyx Jefferson! ...................................... Ditto. Dasypus, Bravard ........................................... Puy deDome. ( c. Kirkdale, Warksworth, Men-) Elephas P rimigenius,Blumj dip^Swansea, Muggendorf,j meridionalis, Nesti .................. .*.*...... ............ Upper Italy, Puy de Dome. angustidens, Cuv. andium, Cuv. ........................................... Andes. (Humboldt) Humboldtii, Cuv. ........................................ Chili. elephantoides, Clift. ..................................... Irawadi in the Birman Empire. latidens, Clift ........................................... Ditto. arvernensis, C. and J .................................... Puy de Dome. Hippopotamus ma ]or, CUT. ................................ { undetermined. ....... c. Palermo, Australia ............ Irawadi. 6. Nice leptorhinus .............. c. Lunel Vieil ................... Cussac. minutus Cuv. ......... ] * %***> P ndl * S UVign - elatus, C. and J ..... ................................ Puy de Dome. undetermined. .......... ................................ St. Privat d'AUier. "ElasmotheriumFischeri.... ................................ Siberia. {c. Bize, Salleles, Argou, Pondres, "] Lunel Vieil, Fouvent, Kirk- | Kostritz, Brunswick, Canstadt, dale, Mendip, Clifton, Ply- I Val' d'Arno, Oxford, Essex, mouth, Swansea ............ [ Yorkshire (frequent) , Law- 6. Nice, Antibes, Gibraltar, Dal- ford, &c. matia, Arragon .............. j Sns ......................... c. Mendip, Bize, Franconia ...... Oxford, Val' d'Arno. other species ............ c- Sandwich ..................... Puy de Dome. *Cho3ropotamus ............. 6. Villefranche-Lauraguais ...... Irawadi. *MericotheriumSibericum.. ................................ Siberia. {Very general in lacustrine de- CnNrSUf^S England, France, Ireland. tarandus priscus ........ Breugue ....................... Europe. tarandus ................................................ Kostritz. dama giganteus ......................................... Abbeville. polignacus ............................................... Cussac. elaphus ................. In English caverns generally .... Frequent in England. Eeboullii, Christol ...... c. Bize, Salleles. several others ........... c. Ditto, ditto. ................... Cussac, Puy de Dome. 6. Gibraltar, Cette, Nice, Antibes, Pisa. Antilope Christollii, M. de S.. c. Bize, Salleles. other species ............. 6. Nice, Arragon ................ Irawadi, Kostritz. Ovis... .. 6. Villefranche-Lauraguais. t c. Salelles, Bize, Lunel Vieil, Bos primigenius, Bojanus..< Argou, Pondres, Souvignar- L gues. bombifrons, Harl ......................................... Bigbone Lick, &c. trochocerus, Von Meyer ................................. Upper Italy. Pallasii, Dekay .......................................... Siberia, New Madrid. Velaunus ............................................... Cussac. undetermined ........... Kirkdale, Mendip, Plymouth, &c. In various parts of England. ( c. Bize, ^Souvignargues, Lunel") Siberia, North America? York- perus priscus, Boj ..... < Vieil, Pondres, Argou, Sal- V shire, and various parts of 1 teles ........................ j Europe. We have not ventured to admit into the preceding list, the numerous remains found in the irony sands of Eppelsheim, which are stated to be related to the tertiary limestones of that vicinity, in 444 DISLOCATIONS or TERTIARY STRATA. which also (see Meyer's Palceologica) bones of rhinoceros, &c. occur. These remains consist of species of gulo, felis, (not those of the caverns,) several small rodentia, cricetus vulgaris ? moschus antiquus, five species of cervus, (not those of the diluvium,) rhinoceros Schleier- macheri, (Kaup,) mastodon angustidens, m. arvernensis, three species of equus, tapirus priscus, lophiodon Groldfussi, sus antiquus, s. palaeochserus, dinotherium giganteum, d. bavaricum, manis gigantea. It may be remarked that in the valley of Khine, and in some other parts of the continent of Europe, where local tertiary seas have left agitated deposits along their shores, and in the line of their currents, it requires extreme caution to apply with propriety the term diluvial. By an appeal to the organic exuviae, where these are sufficiently plentiful, it may often be possible to resolve the doubt, especially where remains of the pachydermata are numerous. Thus elephants, hippopotami, rhinoceros tichorhinus, and certain bovine and cervine remains on the one hand, and, on the other, palaeotheri, lophiodontum, &c. offer strong contrasts. But this test cannot always be applied, and it then becomes difficult to rely on the minute distinctions which probably almost always exist between the tertiary and diluvial species of the same genus. In this research much yet remains to be effected. Cases like those of Eppelsheim and G-eorgesgemund become in this point of view exceedingly important ; for, by a comparison of many such instances, the series of zoological changes on the land, between the beginning of the tertiary and the end of the diluvial periods, may perhaps be eventually determined. At present we can only perceive that in general the palaeotherian inhabitants of Europe had mostly ceased to exist in these limited districts before the elephantoidal races had spread themselves so widely over the northern zones ; and can clearly show that the proportion of species belonging to extinct genera in the older tertiary deposits, was at least half, while in the preglacial deposits and caverns of the same date, it was about one- fifth. The remarkable extinct genus mastodon is common to the pleiocene and diluvial periods, and there may be reason to think that in some of the localities in North America, remains of these animals lie in postglacial lakes, like those which contain in Ireland and Yorkshire the bones of the cervus megaceros. Dislocations of the Tertiary /Strata. After the deposit of the chalk and the plastic clay strata, and after the accumulation upon it of several regular marine and fresh water tertiary strata, extensive disturbances happened, by which the chalk and all the older strata were thrown into new positions, and the whole configuration of the land in the northern zones was greatly changed. SOUTH OE ENGLAND. 445 South of England. In England, the effects of general convulsions at this epoch are very striking in the southern counties, and chiefly referable to two nearly parallel great undulations of the strata, of a peculiar character, ranging east and west. These undulations are of such a kind, that there are two imperfect axes of elevation and two parallel troughs. The northern trough is nearly in the line of the Thames from London to Beading, beyond which it appears to end ; the southern trough is directed along the Solent, towards the extension of the chalk beyond Dorchester, beyond which it also appears to end. The northern line of steep dips passes through the Weald of Kent and Sussex, south of Guilford to Highclere in Hampshire, and is continued along the Vale of Pewsey, but ends towards Devizes. The southern ridge of strata passes through the Isles of Wight and Purbeck, and between Weymouth and Bridport, and ends at some point in the Channel before arriving at Torbay. These great undulations appear evidently caused by violent eleva- tion of the strata, affecting aU the country between and beyond the two lines described ; and it is exceedingly remarkable that the effect of the convulsion is such, that in each case the declination of the strata on the north side is generally very steep or even vertical, as at Guilford on the one ridge, and in the Isles of Wight and Purbeck on the other, while on the south side the chalk in Hampshire, and the green sand and oolitic groups in the Isles of Wight and Purbeck, are nearly level or slope gently to the south. It is further observable, that for a certain length in the middle of each of these ridges the strata are vertical or nearly so, on the north side, but on each side of this length the inclination becomes less and less violent, and at considerable distances, in one of the ridges, is reduced to a gentle slope. Thus, on the northern ridge, the strata are violently inclined along the line by Highclere in Hampshire, (where the chalk attains its greatest elevation in England,) and at Guilford, but both westward toward Devizes, and eastward toward Kent, the slopes become gentle. Also on the southern ridge, the strata are highly inclined north of Weymouth, nearly vertical in the Isle of Purbeck, but absolutely vertical at the western end of the Isle of Wight, and in Culver cliffs (eastern end of the Isle of Wight) instead of being vertical are inclined 70 north. The broad elevation of the weald of Sussex, between these lines, is part of the same From these data we may infer confidently that the disturbing force acted from below large regions, but was determined by local peculiarities and lines of weakness, particular lines, and most violently to certain points in these lines ; and because of the unequal declinations of the strata on the opposite sides of the ridges, we may perhaps admit the force to have been exerted in an oblique direction. This 446 FOEEIGN TEETIAEIES. latter conclusion has often been suggested to us while considering the ordinary phenomena of faults. Foreign Tertiary System. Under what circumstances deposited. The disturbances which pre- ceded the deposit of the whole or the greater part of the tertiary strata, were very extensive, and appear to have operated considerable changes in the configuration of the land, and to have left the European seas, certainly expanded much beyond their present limits, but yet pretty evidently related to the present depths of the Atlantic, Baltic, and Mediterranean. It has long been the custom to speak of tertiary strata as being particularly deposited in basins ; an inaccurate use of this term, for the tertiary strata are not more, nor perhaps so much, separated into basins as many of the older strata. We recognize, indeed, in them a greater local diversity, such as at present obtains, both with respect to the materials deposited and the organic remains entombed, in separate branches of the same sea, or at distant and dissimilar parts of the same coast. The true way of considering the tertiary strata is, to view them as the varied deposits of one long period, produced chiefly in branches of one great ocean, variously divided by the elevated lands. Some particular deposits may perhaps be best explained by allowing the existence of Mediterranean seas, or even salt water lakes. Cases in which fresh water and marine shells alternate must be examined upon their own evidence, to learn whether such alternations were produced in a lake, or at an estuary ; and finally, the true fresh water strata of the tertiary period must be separately treated, having such relations to the marine tertiary accumulations as the fresh water formations of the present day have to the deposits now in progress below the sea. Thus we shall have purely marine strata, marino-fluviatile, or marino-lacustrine strata, and lacustrine strata all referable to the tertiary period, the relative eras of which can sometimes be correctly determined, sometimes satisfactorily inferred, and in other cases only conjectured. The relative age of strata which were deposited in the same branch of the sea, can be determined by observation, even though subsequent convulsions may since have separated the deposit into detached portions, as for instance, the Hampshire and the London marine tertiaries. It can be inferred satisfactorily, even for originally distant deposits, when large suites of organic remains, not differing more than we may expect to happen in such cases, concur with a general analogy of geolgical position ; and in this case, the inference is the stronger, if the data analyzed and referred in portions to successive periods, apply in a similar manner to the two localities. The mineralogical character of the strata is of importance in EUEOPE. 447 proportion as the deposits happened in the same branch of the sea, along the same line of coast, parallel to the same range of moun- tains, or to similar ranges of analogous rocks. In short, tertiary strata may be expected to show close agreement, considerable resem- blance or general analogy, according to the local circumstances of their production, and it is perfectly consistent with geological expe- rience and sound theory, that the clay of Barton Cliff, the calcaire grossier of Paris, and the lower subapennine marls, may be contem- poraneous deposits, deriving their peculiar character from the pecu- liar circumstances of their localities. If we do not so often find in the older systems of strata these great mineralogical contrasts be- tween exactly contemporaneous strata, we must remember that the circumstances of land and sea, when the earlier deposits happened, were more uniform, and that by a long succession of convulsions the tertiary sea was made to flow round islands and promontories, con- taining a vast variety of rocks, reared in deep or shallow waters, and exposed in various degrees to the process of disintegration. We may venture by the aid of what is known of the effect of for- mer convulsions, and the help of the characters furnished by the newer strata, to describe the hydrography of the great European sea in which tertiary strata were accumulated. Extent of the Tertiary Sea of Europe, &c. It may perhaps be described as an immense inland sea, bounded on the west by a broken line of elevated land in Spain, Auvergne, Brittany, England, Scotland ; on the north by the Scandinavian peninsula, Finland ; on the east by part of Russia, the Ural, the mountain circle which encloses the Aral, the Caspian, and the Black Sea, and a line pro- longed through Syria toward the Bed Sea ; on the south by a line including the present Mediterranean, part of the Lybian Sands, and Egypt. This ancient Mediterranean appears to have been connected with the Bay of Biscay and the Atlantic by shallow channels between Angers and Poitiers, and by the line of the Canal of Languedoc. It embraced the North Sea, and so probably communicated with the Northern Ocean, included a part of the Baltic, and was open to the Indian Ocean through the Red Sea. In this vast area rose at that time irregular tracts of land, forming upon the whole two islands. The northern island, stretching in a sweep from the Cevennes to the Carpathians, and including the great plateau of central France, the Jura, Vosges, Schwartzwald, Ardennes, Taunus, Westerwald, Teutoburger Wald, Harz, Erzgebirge, the circle of Bohemian and Moravian mountains, and the long range of the Carpathians. In the southern island rose in partial peaks, and with small surface, the Alps of that epoch, connecting themselves with the Apennines and the mountains of Dalmatia, Croatia, and Greece. The ancient sea of Bohemia and the sea of the Eheinland were 448 FOKEIGN TEETIAEIES. entirely or nearly surrounded by land ; the seas of Switzerland and Hungary expanded into the Black Sea, and contracted their waters into a narrow channel along the line of the Rhone, there to unite with the Mediterranean ; and the basin of Paris appears to have been only partially connected by shallow channels with the North Sea or the Bay of Biscay. its Relation to the Existing Seas. Viewed, then, in connection with existing seas, we may consider the inland tertiary sea in several portions. 1. The arms and branches of the Mediterranean, stretching up the extended Gulf of Lyons, the Sea of Switzerland and Hungary and the extended Adriatic Gulf, washing the eastern part of Spain, Libya, and Egypt, and joining the Red Sea. 2. The dependencies of the Atlantic and North Sea, as the Bordeaux basin, which was also connected with the Mediterranean, the basin of Paris, the great Sea of England and the Netherlands. To these may be joined the area of Northern Germany, Russia, and the countries bordering on the Black Sea and the Caspian. We might perhaps be justified in making a separate division for the latter surfaces, could we appeal to any satisfactory account of the organic reliquiae of countries which as yet are very imperfectly known, For comparison with the English series, we shall first take the example afforded by the basin of Paris, so admirably described by Brongniart and Cuvier, and on that account frequently appealed to as the general type of tertiary formations. Following the general classification of Brongniart and Cuvier, we shall divide the Parisian marino-lacustrine strata into five groups, in the order of their eras : 5. Upper fresh water or epilimnic group. 4. Upper marine (sands and marls.) 3. Lower fresh water or palaeotherian group. 2. Lower marine (calcaire grossier.) 1. Plastic clay group, subdivided by M. Brongniart into three parts. Plastic Clay Group. Our remarks on these deposits will be as concise as the great interest attached to a right understanding of the mode of their formation will allow. The idea we form to ourselves from a consideration of the plastic clay group of England, is that of a varied series of deposits, consequent upon some considerable con- vulsions, partly derived from the waste of the cretaceous system, and accumulated in a sort of estuary of that system. Pebbles and sands, with or without shells in confusion, a few bands of clay with shells, and beds of lignite, layers of pipe-clay, and plastic-clay, lying in sand, compose the rather heterogeneous group, which ends upwards with the abundant tranquil deposit of London clay. On the great scale, the plastic clay group of the basin of Paris presents very analogous characters. It rests on the irregular and worn surface of the chalk, contains accumulations of pebbles, beds of PAEIS BASIN. 449 lignite, layers of coloured plastic clay, and by occasionally including beds of calcaire grossier, analogous to the shelly layers of the English group, appears to leave hardly any important point of resemblance unsatisfied. On a careful review, however, some differences arise. The order of succession of the several parts is not exactly similar. The French series taken generally may be thus expressed : Upper part consisting of potter's clay, marls, sands, and much lignite, the clay con- taining many lacustrine shells, as cyrenae and melanopsides, alternating with a few marine shells, as ostrese and cerithia; the lignites containing remains of mammalia and fresh water reptiles. Middle part or plastic clay and sands, sometimes alternating, the former generally beneath, of very uncertain thickness, indistinctly stratified and devoid of shells. Lower part very local, consisting of fragments of chalk, flints, &c. These deposits are very unequally spread in the basin of Paris, and the lignite with shelly clays and marls belongs principally to the vicinity of Soissons. We may draw the following inferences. (1.) That the convulsive movements which wasted the chalk of England, and raised its originally deep strata to a littoral and estuary situation, were also experienced in the basin of Paris. (2.) That in this estuary irregular deposits happened, both marine and fresh water, the latter prevailing in particular places more than in the correspond- ing basins of England, and recognized by distinct layers of fluviatile mollusca, sometimes alternating with deposits containing a few marine shells. The basin of Paris seems therefore to have been at first an estuary, admitting into it considerable currents of fresh water from rivers or lakes, containing shells, crocodiles, and turtles, and transporting vegetables ; but the deposits were generally more tran- quil than the contemporaneous, or rather somewhat earlier, products of England. The " lower marine" group, or calcaire grossier, and its coeval and associated sandstones, form the principal and characteristic rock of the Paris basin, in which the vast number of marine shells occur. The calcaire grossier is a granular, sedimentary, sandy, yellowish- white limestone of considerable thickness, regularly bedded and jointed, with partings of a marly nature, including occasional beds of sand, and in some cases lignite and marls. The lowest part of the rock is usually filled with green silicate of iron, and can hardly be distinguished from some kinds of marly green sand. It contains hardly the least trace of metallic substances, but encloses a few com- pact siliceous beds, some cubic fluor, quartz, and calcareous spar. It is the building stone of Paris. In some parts, it is replaced by a develop- ment of sandy beds, which often exhibit glistening fractures. Pebbles lie in it, chiefly at the top and the bottom. Upwards of 1,500 species of marine shells belong to this group, and only a very few land or fresh water species, rarely brought down with vegetables, diversify 2 Or 450 FOEEIGN TEKTIAEIES. the character of the deposit. A great proportion of the shells of the Barton clay are recognized among the more numerous reliquiae of the Paris basin. The lignite and marls occasionally included near the top of the calcaire grossier (Brongniart,) remind us that the action of the fresh waters, though nearly unobserved during this long period of depositions in quiet sea, might easily be recalled to the basin of Paris by a change of local circumstances. Such a change occurring, a part of the basin of Paris was sur- rendered for a time to the undisputed possession of fresh water, and the following group was deposited. Palaeotherian, or Lower Fresh Water Group. The palaeotherian, or lower fresh water group, is principally, says M. Brongniart, a che- mical deposit from water, or at least this mode of origin is very frequently to be traced in it. Coarse mechanical aggregates, the result of violent currents, are unknown in it ; while gypsum, sili- ceous nodules, and agates are frequent, and sulphate of strontia, carbonate of lime, and silicate of magnesia occur in the marls which compose a large part of the mass of the formation. But it is from the remains of terrestrial and fresh water plants, and the exuviae of land and fresh water animals, that this group of strata receives its most exact as well as most interesting characters. In the interior of its mass no marine bodies of any kind have been found, but several plants and shells of the land and fresh water, generically identical with existing tribes, as well as land quadrupeds belonging to genera now extinct. The study of these quadrupeds first awakened in Cuvier that indefatigable zeal in the examination of fossil animals, which has established the permanent union of the highest branches of geology and zoology. Argillaceous and calcareous marls with limnseae, frequently alter- nating in very thin laminae, (a common character of lacustrine deposits of all ages,) constitute the mass of this palaeotherian group; gypsum in broad crystallized masses, of a vertically prismatic struc- ture,* not stratified, is frequently associated with them, as in the basin of Paris, at Puy en Velay, and at Aix en Provence, siliceous limestone locally diversifies them, and yields agates, menilites, nectic quartz, &c. To this group M. Brongniart also refers the lignites which lie in the molasse of Switzerland. The quadrupedal reliquiae are, perhaps exclusively, found in the gypsuni, and few other organic bodies accompany them. This evidently fresh water group occurs in many parts of France, sometimes, as in Auvergne and Cantal, without the least trace of a * Mr. Chantrey, whose unrivalled eminence in his profession was united with very extensive and accurate information on other subjects, observed in the interior of plaster casts of larpe Btatues, which had been subjected to a drying heat of 350, an irregularly prismatic structure, comparable to that of the gypsum of Montmartre. FEA^CE. 451 genuine marine tertiary basis. About Montpellier it is found in combination with marine deposits nearly as in the Paris basin, and there appears good reason to believe that the causes which repelled the sea from that basin were extensively at work in other parts of Europe. This indeed is not a very difficult part of the problem. The expulsion of the sea may easily be imagined to have happened by the elevation of new land, or by a great local dislocation, such as we know to have often occurred ; and thus a fresh water deposit in the basin of Paris might be laid on a basis of immediately antece- dent marine tertiary strata, at the same epoch that in other parts of France elevated above the sea before the tertiary period, these depo- sits were laid on any of the older rocks. From the estuary or lake which we now call the basin of Paris, to the mountains of Auvergne, there might be formed, contemporaneously (that is, in a given geo- logical period), many fresh water deposits of varying character, under varying conditions, which are to be ascertained by special investi- gation of each case. But after the completion of this lower fresh water deposit, subterranean movements brought back the sea into the basins of Paris and Montpellier, at the same time that marine exuviae were introduced into the basin of Hampshire. It does not follow, as a necessary inference from the data before us, that this subterranean movement was centred below the basins of Paris, Montpellier, and Hampshire. It is only certain that subterranean movements must have occurred in such a manner as to interrupt and restore at intervals the connection of these districts with the ancient sea. In what respect is this different from the case of the Weald of Sussex and the ancient coal basin of Yorkshire ? Upper Marine Oroup. The "upper marine" group, produced in the basin of Paris by the marine irruption which covered the palaeo- therian gypseous marls, is composed chiefly of sands of many colours, occasionally indurated to stone, with fewer shells than in the lower marine group. The base of the group is, at Montmartre, a mass of calcareo-argillaceous marls, greatly analogous to those of the fresh water group below, a gradation of character very much to be ex- pected. Conglomerates lie on the coloured sands in the northern and eastern parts of the Paris basin. A sandy, shelly limestone, containing bones of the paleeotherian, and also of the subsequent diluvian era, called cakaire moellon by M. de Serres, abounds at Montpellier and Narbonne. The molasse of Switzerland, a very complex and disturbed deposit, is referred to this era. Upper Fresh Water and Epilimnic Groups. The parallel between the three basins of Hampshire, Paris, and the south of France, is drawn still closer by the occurrence in all three of " upper fresh water " beds. It must in some cases be doubtful whether the upper fresh water deposit recognized . in a tertiary district be of the anti- 452 FOBEIGN TEBTIABIES. quity of this Parisian epilimnic group, and it is highly prohable that lacustrine deposits will be found of all intermediate ages from the date of the uppermost tertiaries of the Paris basin to the deposits of the modern era. Such, perhaps, are the lacustrine groups of (Enin- gen and Georgesgemund, which have become better known to the English reader in consequence of Murchison's descriptions. But, in the case of the localities 'mentioned above, this doubt is not to be entertained. The most characteristic rock of this group in the basin of Paris is the millstone, a siliceous rock full of cells and tubular sinuosities, attributed to the extrication of gas from the bed of the lake, as is known to happen in ordinary cases, and some fresh water shells and seeds of chara. (Gyrogonites.) In other districts, espe- cially in Italy, a marly limestone, analogous to the travertine which is daily formed there by carbonated springs, is considered by Brong- niart the representative of this group, but it is obvious that this tufaceous deposit may be of all ages. The upper fresh water deposit, with, probably, other recent deposits of the same nature, is recog- nized in Auvergne and Cantal, on the Loire, Allier, and Cher, in the department of Gard, in Switzerland, Austria, and Hungary. Faluns of Tom-nine. To these characters of the strata in the Paris basin, described by MM. Brongniart and Cuvier, must be added a notice of a set of gravelly sands in the Faluns of Touraine, long celebrated for abundance of shells and other organic remains, but which were first examined with attention by M. J. Desnoyers. Along the line of the Loire valley at several points, as well as at Rennes, shelly and gravelly deposits occur, which, from Desnoyers' investigation, appear certainly to be of a posterior date to the whole Parisian formation, and to contain not only a variety of shells and corals distinct for the most part from those of the Parisian tertiaries, but also a mixture of quadrupedal remains, both of the palseotherian and mastozootic era. Besides palaeotherium, lophiodon, and a species of anthracotherium, which would generally be referred to the era of lacustrine tertiaries, there are bones of mastodon, hippopotamus, rhinoceros, tapir, horse, and deer. These, the most recent, probably, of all the deposits connected with the Parisian series, were compared by M. Desnoyers with the English crag ; but the propriety of this reference was denied by Lyell, on the ground that their suites of organic remains have not the same ratio of analogy to existing tribes. The Faluns are taken by this geologist as typical of Meiocene de- posits. The affinity of the deposits of Touraine and Suffolk is, how- ever, remarkable, and is admitted by D'Orbigny. Thus a sequence of tertiary deposits of the same general characters appears to be clearly ascertained in the southern parts of England and the northern parts of France, and the beds in the two localities indeed the same, or nearly the same geological period. ENGLISH AND FOREIGN TERTIARIES COMPARED. 453 a Cf 111 II II II s s* S-s I! II 05 1-3 s (-< -3 -2 2*8 11 454 rOEEIGOT TEBTIARIES. This agreement is very interesting. Yet it is not to be thought that in other parts of Europe, which have not been subjected to the same repeated convulsions, a similar sequence of marine with similar interpolations of lacustrine deposits should often be met with. On the contrary, it ought to be expected that when the tertiary deposits are wholly marine, the triple character, which in France and Eng- land they derive from definite periods of convulsion, should be con- founded into a general series of many graduated or alternating terms, as happens to the oolitic and other extended marine systems. The further descriptions of tertiary strata, introduced for comparison with those of England, will be divided into marine and lacustrine ; the former will be first noticed. South of France. The tertiary strata of the south of France are generally coeval with the upper groups of those of Paris, and the greatest assemblage of shells and other marine remains lies in sandy and subcalcareous beds, thought by M. Brongniart to be of the same age as the interlacustrine sands of Paris. In the districts of Bor- deaux and Dax, 600 species of shells have been collected from these strata, which Lyell arranges in four divisions thus : 4. Siliceous sand without shells. 3. Gravel. 2. Sand and marl with shells. 1. Blue marl with shells, sometimes 200 feet thick. Below all these calcareous strata occur with shells of the Paris basin. M. de Serres has shown the much greater accordance which the Bordeaux and Montpellier shells bear to those of the subapennine formation of Italy than to the strata of the basin of Paris, and it is from comparison of the organic remains that Lyell ranks together the Bordeaux and Touraine shells, and puts them above all the Parisian beds. It is desirable to attain an accordance of opinion in the relative age of these strata, because they furnish common ground of comparison for the deposits which border the Apennines, the Alps, and the Carpathians. North of the Alps. The most complete section of tertiary strata along the Alps has been furnished by the researches of Murchison and Sedgwick in Lower Styria. Uppermost group, calcareo-arenaceous. Calcareous sands and pebble beds, calcareous grits and oolitic limestones, containing many shells, some of these of existing species. White and blue marl, calcareous grit, white marlstone, and concretionary white limestone with shells. Middle group, calcareous. Below this is a coralline limestone with shells, in one place 400 feet thick, associated with marls. GEBMANY. 455 Lowest group observed. Conglomerate with micaceo-calcareous sand, and millstone conglomerate. Blue marly shale and sand, with shells analogous to those of the calcaire grossier and London clay. Shale and sandstone with beds of lignite, accompanied by fluviatile and terres- trial exuviae. Conglomerates, grits, and micaceous sandstones. The coralline limestone here mentioned serves as a good line to connect the sections along the line of the Carpathians. At Vienna, Murchison and Sedgwick give the following series : Alluvial beds? of loss and gravel, the latter containing bones of mastodon, tapir, anthracotherium, &c. Fresh water limestone. Leithakalk or coralline limestone and calcareous conglomerate. Lower group. Upper blue marls and sands, very rich in shells, yellow sand and shells. Lower blue marls 300 feet, compared to London clay. Transylvania, & c . In Transylvania, Boue gives the series thus : Upper group shelly sands, marine and fresh water. Sandy coarse limestone, equivalent of the Leithakalk. Molasse. Clay and marls blue and yellow. And this applies to Moravia and the west of Hungary, where the lower beds are inclined toward the Carpathians. Gosau Beds. Below all these tertiary strata, in geological position, but raised to a great height in the Alpine region by powerful dislo- cations, occur those shelly marls and sands with conglomerates and traces of lignite, which have acquired celebrity from the researches of Murchison, Sedgwick, Boue, Von Lilienbach, and other geologists. The discussions on their relative age are even yet unsettled, because no sections can be obtained, under the difficult circumstances of the case, which put in a clear order of uninterrupted succession the whole mass of tertiaries, or allow a very confident deduction concerning the relation of all the parts taken separately. The obscurity of the sub- ject is increased by the admitted indistinctness and variation of mineralogical character in the tertiary sands and conglomerates of the plains of the Danube. Yet it is not to be supposed that no inferences can be grounded on the laborious investigations of the eminent geologists above named. The Grosau shelly beds are limited below by the Alpine limestone at Gosau, and in the Eentersberg by the same limestone (hippuritic), covered by gray or reddish marls and marlstone containing a few fossils of the chalk formation : above, these beds are known to pass under the molasse of the plains north of the Alps. Two sections, derived from the labours of Mur- 456 FOREIGN TERTIARIES. ehison and Sedgwick, will, with this understanding, sufficiently show the nature of the beds. The first is across the Valley of Gosau : Uppermost group. Red and green slaty micaceous sandstone several hundred feet thick. (Cap of the Horn.) Second group. Green micaceous gritty sandstone, extensively quarried as whetstone, succeeded by yellowish sandy marls. (In the Ressenberg.) Third group. Vast shelly series of blue marls, alternating with compact limestone and calcareous grit ; traces of vegetables above, abundance of shells and corals in the middle and lower part. (In the Valley of Gosau.) Lowest group. The above series gradually changes to beds of a more conglomerate character, which pass into red sandstone and marl containing gypsum ; a coarse conglomerate, forming the base of the whole system, rests upon and abuts against the Alpine limestone. (Russbach.) The discontinuity between the lowest part of this section and the top of the Alpine limestone is partially remedied in the Untersberg, where a series of four terms likewise appears. Uppermost group. A great succession of alternating masses of bluish micaceous marl, slate, clay, sandstone, and conglomerate. Some of these marls contain beds of gypsum and fossils resembling the suite of Gosau. Second group Beds of blue micaceous slate clay, and greenish micaceous sandstone. Third group. Sandy micaceous marls, alternating with conglomerates and micaceous calc grit with nummulites. Subordinate to this system are red and variegated marls with gypsum. Lowest group. A great deposit of marl and marlstone, generally of a gray, but in some places of a red colour; containing a few fossils resembling those of the chalk formation. These beds are conformed in declination to the Alpine limestones of the Untersberg. Age of the Gosan Beds. Murchison and Sedgwick conceived these Gosau beds to be the lowest of the tertiary series of the country, and to have so much analogy to the system below as to be properly re- garded as one of the connecting links of the cretaceous and tertiary rocks. M. Boue ranked them with the green sand system. On ap- pealing to the organic remains, we learn that the affinity of genera, and the proportion of univalves and bivalves, bring the Gosau beds to a tertiary type ; an examination of the species leads M. Deshayes to declare (Lyell, vol. iii. edit. 1,) that none of the Gosau shells are found in any recognized tertiary stratum, but that some of the most characteristic species of Gosau occur in the green sand below the chalk at Mons in Belgium. His researches have led him besides to the following decisive general statement, that no shell has yet been found which is common both to tertiary and secondary strata ! Our own impression on the subject, derived from comparing the state- ments of those eminent writers who have enjoyed the fullest advan- tages of original examination, can be of no importance on either side ; SWITZEKLA1ST) ITALY. 457 it will be more useful to set an example, unfortunate!}' rare in such discussions of deliberate indecision, and to appeal to future discoveries. Two remarks, however, must not be omitted. Though all the in- stances upon record should be found strictly to agree (even when modified by further discoveries,) with that valuable and practical conclusion for which geology is indebted to Deshayes, yet this con- clusion is not universal, and cannot be employed to predicate the result of any new investigations on the boundaries of successive systems of life in the strata. And again, though certain genera may not yet have been recognized among secondary strata, the de- duction of the age of the Gosau beds from this source is of the same conditional character. Moiasse. The primary and secondary Swiss mountains are bor- dered on the north by a vast thickness of conglomerates, sands, cal- ciferous grits, and lignites with mammiferous quadrupeds. These are referred by Brongniart to the interlacustrine marine beds of Paris, but the shells as yet found in it are few. M. Studer, of Berne, has amply described this immense and disturbed deposit. Subapennine Deposits. The subapemiine strata are all that remain to be noticed in these comparative sections. No one since Brocchi has been more successful in the examination of these strata than Lyell, and they furnish much of the evidence which supports his classification of the tertiary system into eocene, meiocene, and pleiocene formations according to the degree of analogy which the organic fossils of those groups bear to existing races of marine ani- mals.* They are of enormous thickness (several thousand feet), and must have required very long periods for their accumulation in the Mediterranean, from which they have been uplifted to consider- able elevations on each side of the secondary Apennine ridges. The mass consists of innumerable alternations of calcareous and argilla- ceous marl, light brown, or blue ; but the variation of mineral cha- racter is slight through the whole series, and not at all sufficient to furnish permanent marks of separation into groups. It is altogether like the sediment which we may suppose to be quietly deposited on the bed of the Mediterranean by rivers which have left their coarser detritus inland. Beds of lignite are sometimes interstratified, as at Medesano, near Parma. Subordinate beds of gypsum interstratified with shelly marls and sand also occur in the Parmesan. Sandstone is also interstratified, and rarely compact limestone replaces a portion of the calcareous marls. The whole is covered in places, and une- qually, by a coarse yellow sand and conglomerate, in which alterna- tions of fluviatile and marine exuviae are traceable, and other circum- stances are observed which mark estuary or littoral action. * These terms are derived from xetivog (recent), combined with tug (the dawn), (tiiuv (less), and 3-Ac/o/y (more). 458 FOBEIGN TEETIAKIES. This may be taken as the character of the middle subapennine for- mation. The tertiary strata in the hill called the Superga, in Pied- mont, have been described by M. Brongniart and other writers, and from personal examination (with Murchison) Lyell has inferred that they are the oldest part of the tertiary system in Italy. Fine green sand and marl, and a subjacent conglomerate (the boulders being of primary rocks), compose these strata, which dip at the extreme angle of 70, under the more horizontal bluish subapennine marls of the plains of the Tanaro. Sicilian Deposits. The most recent portion of the subapennine deposits is exemplified by Lyell in the tufaceous formations of Naples, the calcareous strata of Otranto, and probably the greater part of the tertiary beds of Calabria. But the most satisfactory view of the newest tertiary strata is obtained in the Val di Noto, Sicily. Since Dr. Daubeny's account of that island, the phenomena of its stratified rocks have excited much attention, and Lyell has been eminently successful in deriving from them important inferences concerning the relative ages and periods of elevation of submarine strata. The fol- lowing is an abstract of his descriptions. The whole series of strata in the Val di Noto is divisible into three principal groups. The uppermost group consists of limestone, sometimes 700 or 800 feet thick, often corresponding in mineral character with the calcaire grossier of Paris, but often more compact. It is regularly stratified and cavernous. These characters, however, are liable to vary in different parts of the island. Near Noto it has the concretionary spheroidal structure of the form of the Italian travertine, and con- tains terrestrial vegetables. These strata prevail not only in the Val di Noto, but, as Dr. Daubeny stated, cap the hill of Castrogio- vanni, 3,000 feet above the strata. The organic remains of this limestone (generally casts) belong, with hardly any exception, to existing species. The middle group, not abruptly distinguished from the upper one, consists of white calcareous sand, sometimes with a tendency to oolitic and pisolitic texture, such as the travertine of Tivoli. At Floridia, near Syracuse, it changes to conglomerate with calcareous pebbles, associated with sandy limestone full of broken shells. In some parts of Sicily this group seems to be represented by yellow sand, exactly resembling that superimposed in the blue subapennine marls of Italy. The lowest of the three groups consists of an argillaceous deposit of variable thickness, called creta in Sicily. It resembles the blue marl of the subappenines, and encloses shells and corals in a beauti- ful state of preservation. The shells belong, with few exceptions, to recent species. FBESH WATER BEDS. 459 Other marly strata, probably tertiary, occur below, with gypsum, sulphur, and salt. Lacustrine Tertiaries. A few cases, selected from the great num- ber of tertiary lacustrine deposits, for the sake of some peculiar facts which they display, may now be introduced, to illustrate the con- dition of the surface of the land during the tertiary epoch. In general it is to be observed that, just as at the present day lakes sometimes occur on certain streams, in several parts of the valley, at different heights above the sea, and spread their waters over the Jura limestone, chalk, tertiaries, or primary strata, according to the nature of the country, so it was in the older time ; and no criterion of the age of a fresh water deposit is to be drawn from the marine nature of the strata on which it rests, beyond the mere inference that it was posterior to such strata. If, as must frequently happen, the circumstances of these different lakes are unlike, the deposits in them may be related neither by similarity of order, nor identity of composition, but it is probable that some analogy will be traceable in their organic remains. In the basin of Paris, gypsum occurs only in the lower fresh water deposit, yet the gypsiferous fresh water deposit of Auvergne is sup- posed by Brongniart to be of the age of the upper fresh water deposits. Central France. The fresh water district of central France occu- pies considerable tracts along the lines of the Loire and the Allier, and is extended northwards on the latter river, so as to approach towards the proper basin of Paris. Interesting phenomena are pre- sented by these deposits, where they have been subjected to volcanic agency about Clermont, the Cantal, and Puy in Yelay. Along the Allier, granite is the general basis of the fresh water strata, which consist of sandstone and conglomerate, containing pebbles of all the primary rocks of the vicinity, but not of the volcanic rocks. Above these are green and white very finely foliated marls, full of the small bivalve crustaceous shells of cypris ; thin tufaceous limestones, some- times full of the larva-cases of phryganidaB ; and the highest group of all in a few places is composed of gypseous marls. The most singular fact mentioned by Lyell and Murchison, in their description of this country, is the remarkable condition of these groups. The lowest con- glomerate series puts on almost exactly the appearance of the English old red sandstone, with its purple and green spotted marls, and even its nodular limestone or cornstone ; and the limestone in the upper part of the series actually becomes oolitic at Yichy and Gannat, and yields a building stone like that of Bath, and of equal beauty ; soft in the quarry, but gathering hardness by exposure. With what astonishment would the geologist, acquainted with the fossils of the English oolite, gather in this oolite of Gannat, land shells and bones of quadrupeds, like those of the gypsum of Montmartre ! 460 FOREIGN TEETIAEIES. The lacustrine formation of the Cantal rests in the same manner upon primary rocks, with san(ty and gravelly beds below, gypsiferous marls, beds of flint and limestone above. This fresh water limestone, and its accompanying flints, are described by Lyell as possessing a strong resemblance in mode of arrangement to the marine chalk and flint ; the flint of the fresh water, black within, white without, and undergoing the same changes of superficial colour on exposure as the chalk flints of England. Provence. The same geologists have been very successful in tracing the fresh water deposits of Aix in Provence, which have yielded a large number of fossil insects, some fishes, and land plants of existing genera. M. De Serres also has described this locality, and studied the insects with attention. The general basis of the Aix tertiaries is a rock of the oolitic system, inclined and contorted in position, with gryphsea, belemnites, and ammonites. The lacus- trine deposits are in the lower part a series of carboniferous lime- stones and shale, with stony bituminous coal in several seams which altogether amount to five feet in thickness. The limestone is com- pact, gray, blue, and black, and resembles the mountain limestone of England. Fresh water shells (cyclades, melania, planorbis, unio) accompany these beds, and gyrogonites are found in the coal itself. Micaceous sandstones and shales, with earthy limestone and limnseae, come on above ; and these are succeeded by red marl and fibrous gypsum, also characterized by the presence of limnsese and planorbes. Under and above the town of Aix, the upper series of the basin is observed to consist of red sandstone and conglomerate, covered by white and pink -coloured marlstone and marl ; and above all is a triple succession of gypsum and marls, overlaid by white calcareous marls and marlstone, with calcareo-siliceous millstone and resinous flint, containing land and lake shells. It is in these beds that the fossil fish occur abundantly, and leaves and branches of flabellaria, laurus, buxus, &c. are found. The insects are obtained from a part- ing in the upper gypseous beds. They are, with one exception, all land insects ; and from the united testimony of M. De Serres and Mr. Curtis, referable or nearly related to existing genera, principally of the orders diptera and hemiptera, some coleoptera and hymenoptera, but only one lepidopterous insect ; sixty-two genera are particularly enumerated by M. De Serres. May we not compare this curious fact in tertiary geology, and the parallel case at (Eningen, to the col- lection of insects, leaves, and branches, which, when swept down by spring or summer floods, affords a rich harvest to the entomologist on the borders of the rivers in the north of England ? CEningen. The limestone quarries of (Eningen, near Schaffhausen, have long been celebrated for abundance of mammalia, birds, reptiles, fishes, insects, and plants, identical or very similar to existing kinds. LIGNITE. 461 The section of the whole deposit is given by Murchison, who brought from this locality, in 1828, one of the most remarkable fossils which has ever been found the entire and connected skeleton of an ani- mal resembling a fox. The upper quarries offer a section of thirty feet, the beds changing downwards from brown clay into cream-coloured indurated marl, and afterward into a fissile fetid marlstone, containing flattened shells of planorbis, small limnseae, and cyprides ; to these succeeds light-coloured, fetid, calcareous building stone, beneath which is a finely laminated bed, containing insects, cypris, shells of anodon, and many plants ; then follow two thin beds of fetid lime- stone, in the upper of which a large tortoise was found, and in the lower one the fox. Below are slaty marls and marlstones, limestone, and building stone, with a repetition of finely laminated layers of marl, with plants and fishes; tho general base is the molasse of Switzerland. Excepting this animal, which is much allied to the common fox of Europe, all the other quadrupeds found here are rodentia. The insects and plants belong to European genera. Prof. Heer, of Zurich, has lately collected and investigated the extinct Flora and Fauna of these famous excavations. These descriptions of some of the most interesting lacustrine de- posits, will render it unnecessary to particularize other numerous cases in Switzerland, Germany, Hungary, Italy, and Spain, which present nearly the same phenomena, and appear to occupy the whole interval of time from the lower fresh water formation of Paris to the glacial era, and to be represented by an equally continuous series of detached desiccated lakes from that era to the present time. Lignite. There is, however, another kind of fresh water deposit which requires a short notice. Lignite, or wood coal, has long been known in France, in connection with the plastic clay group and other more recent strata, and also in the Isle of Wight. The same kind of carbonaceous deposit is of value in the molasse of Switzerland, and very extensively spread over the north of Germany, and in the valley of the Rhine ; it also interlaminates extensively the marine tertiaries of the basin of Vienna and the border of the Carpathians : lignitic coal has therefore been considered as even peculiar to the tertiary era. This is not quite correct, yet the generalization is of more importance than perhaps we may at present perceive. The whole mass of these lignites is made up of land plants, mostly or wholly of dicotyledonous tribes, and they are accompanied by marls, land and fresh water shells, and, in places, by the bones of paleotheria, anthracotheria, beaver, &c. The fixing of their relative age is hardly possible by evidence drawn from themselves alone, for the shells and plants are few, and the quadrupedal remains very local. If we attempt to fix their date by that of the marine strata which they divide, the uncertainty of the latter datum must, in a great 462 LIGNITIC DEPOSITS. measure, at present frustrate the attempt. Perhaps the most recent deposit of this kind mentioned on the continent, is that described by De Beaumont as associated with the older diluvium, as it has been considered, which that author ascribes to the uplifting of the western Alps. This deposit bears marks of slow and tranquil accumulation in a lake, contains planorbes in the layers of clay which alternate with it, and sometimes shows as many as four beds ; it rests on and is covered by pebbles, which indicate violent watery action. It is highly probable that lignite has been formed at many periods, and that deposits of this kind will be found at intervals from the plastic clay, through the diluvial gravel and clays to the modern alluvial peat bogs, which they so much resemble in alternation and repetition of materials, paucity of shells, occasional occurrence of quadrupedal remains, arid almost every obvious circumstance. Lignite of Bovey Tracey. Bovey Tracey, in Devonshire, is the only locality in England where tertiary lignites are worth working ; the exact geological age of this deposit is riot known at present. Pipe-clay of some value lies with it. Dr. Miller, in the Phil. Trans., vol. li., describes this deposit in a very interesting manner. The whole series dips to the south about twenty inches in a fathom. The perpendicular thickness of these strata, including the beds of clay with which they are intermixed, is about seventy feet. There are about six of each, and they are found to continue eastward, in an uninterrupted course, to the village of Little Bovey, a mile distant, and probably much farther. The strata of coal, near the surface, are from eighteen inches to four feet thick, and are separated by beds of brownish clay, nearly of the same dimensions, but diminishing in thickness downwards, in proportion as the strata of coal grew larger ; and both are observed to be of a more compact and solid substance in the lower beds. The lowermost stratum of coal is sixteen feet thick ; it lies on a bed of clay, under which is a sharp green sand of seventeen feet thick, and under that a bed of hard coarse clay, into which they have bored but found no coal. From the sand arises a spring of clear blue water, which 'the miners call mundic water, and a water of the same kind, trickling through the crevices of the coal, tinges the outside of it with a blue cast, derived from phosphate of iron. Amongst the clay, but adhering to the coal, are found lumps of a bright yellow loam, which burn with an agreeable scent. (Eetin- asphalt.) Some of the coal is black, and nearly as heavy as pit coal ; this is called stone coal ; but the most remarkable sort resembles wood in the grain and appearance so much as to be called wood or board coal. Some plants like grass and reeds lie in the alternating clays, which are in part carbonaceous. The following section of the Meissner by M. Herndeshagen OBGANTC EEMAINS LACTJSTEINE. 463 (Leonhard Taschenbuch, 1817) gives the most usual relations of the brown coal and basalt of that celebrated locality : 1. Dammerde. 2. Greenstone and basalt, 50 to 80 fathoms 300 to 480 feet. 3. Schwiil (blind coal), a bituminous laminated clay, hardly to be distinguished from true coal ^ to 5 feet. 4. Kohlenfloz, in all 3 to 14 fathoms thick, viz. : a. Stangenkohle (prismatized) 1 to 4 ft....*] b. Glanzkohle (sp. gr. 1-438) 3 to 18 ft,... | , c. Pechkohle (sp. gr. 1-346) 3 in. to 3| ft... ! . . d. Brownish black (sp. gr. 1-259) 3 to 4 ft.... { e. Light brown light coal (sp. gr. 1-230) 4 to 8 fath. | f. Fossil wood, called stockwerk 6 in. to 4 ft. ... J 5. Liegende (sill or sole of the coal), sp. gr. 2-545. 6. Triebsand fath. 7. Blue marl, on the east of the mountain, with gypsum 10 to 15 fath. 8. More or less friable sandstone 1 fathom, then sandstone to the foot of the mountain on the east side, but on the west side muschelkalk. EXAMPLES OF ORGANIC REMAINS OF LACUSTRINE TERTIARIES. PLANTS. FROM M. ADOLPIIE BRONGNIAKT. Cryptogamia cettulosa. Muscites Tournalii Armissan near Narbonne. squamatus Longjumeau near Paris. Crypt, vasculosa. Equiset. brachyodon Armissan. Filicites polybotrya Ditto. Lycopodites squamosus Paris. Chara Lemani St. Ouen near Paris. tuberculosa Isle of Wight, medicaginula Montmorency, Sanois, Trappes near Paris. helicteres Pleurs, Department de 1'Aisne. Phanerog. gymnosperma. Pinus pseudostrobus Armissan. Taxites Tournalii Ditto. Phanerog. monocotyledonea. Smilacites hastata Ditto. Flabellaria Lamanoni Aix en Provence. Endogenites Montmartre. Poacites Aix. Phanerog. dicotyledonea. Comptonia dryandraefolia Armissan. Betula dryadum... Ditto. Carpinus macroptera Ditto. Phyllites Isevigata Aix, Armissan, Pavia, c. Geslini Aix. 464 OEGANIC EEMAI^S LACT7STBINE. Nymphaea arethusa Longjumeau. ?Culmites anomalus Ditto. Carpolithes thalictroides Ditto, Me of Wight. ovulum, Longjumeau. Exogenites Palaiseau. COXCHIFERA. Unio Solandri, Sow Isle of Wight, Hordwell. Cyclas Aix en Provence. .Anodonta Lavateri (Eningen. Mya? gregaria, Sow Headen Hill. Corbula nitida, Sow * Isle of Wight. Cyrena pulchra? Hempstead Bay, Skye. Mytilus Brardii, Sow Hordwell. MOLLUSCA. GASTEROPODA. Planorbis rotundatus, Sow Paris, Salinelle (Gard), Quercey. cornu Paris. euomphalus, Sow Isle of Wight. prevostinus Ditto, Paris. Planorbis prominens Salinelle. compressus Ditto. lens Isle of Wight, Paris. cylindricus, Sow Isle of Wight. Limnsea fusiformis, Sow Headen Hill. minima, Sow Ditto. maxima, Sow Binstead. longiscata, Lam Headen. pyramidalis, Sow Ditto. columellaris, Sow Hordwell. cornea Paris, Colle en Siennois. fabulum Paris. ventricosa Ditto, Bruere. (Cher.) inflata Bruere. cylindrus Ditto. strigosa Le Locle near Neufchatel. elongata Paris . acuminata Ditto. sequalis Salinelle. pygmsea Ditto. ovum Paris. Paludina affinis Salinelle. impura Quercy. Hammeri Isle of Wight, Bouxweiler. carinata Paris. Ancylus elegans Hordwell. deperditus Salinelle. Melania fasciata Isle of Wight. Melanopsis carinata Newport, Isle of Wight brevis Hordwell, &c. OBGAtfIC EEMAIKS LACUSTRINE. 465 Phasianella orbicularis Shalcomb, Isle of Wight angulosa Ditto. minuta Ditto. Potamidum Lamarckii Paris, Aurillac, Nonette, near Issoere. acutum Isle of Wight. ventricosum Ditto. Indusia tubulata? Moulins, Auvergne, Colle. Cyclostoma truncatum Paris, Carnetin. elegans antiquum Paris. mumia Ditto. Helix globosa Shalcomb, Isle of Wight. Lemani Paris. Desmarestina Ditto. Eamondii Orleans, Auvergne. Cocqui Ditto, ditto. Bulimus pygmaeus Paris. terebra Ditto. atomus Paris, Le Puy. pusillus Ditto. Pupa Defrancii > Paris and Auvergne, muscorum j in a pipeline. ARACHNIDA, INSECTA, &c. Aranea Aix in Provence. Phrynus. Coleopt. Dyticus. Staphylinus. Buprestis. Melolontha. Curculionidae 10 Trogosita. Hylophagidae 5 Orthoptera 8 Hemiptera 20 Neuroptera. (Libellulidae.) Hymenoptera 8 Lepidoptera 2 Diptera 15 FISHES. Mugil cephalus Aix in Provence. Perca minuta Ditto and Paris. Cyprinus squamosus Ditto ditto. bipunctatus (Eningen. jises Ditto. capito Ditto. minutus Paris. ictus Rochesaure. (Ardeche.) tinea..., ... Cadix. 466 MODEEN CAUSES IN ACTION. CHAPTER XV. DEPOSITS OF THE MODEEN EEA. MODEEN CAUSES IN ACTION. Relation of Terraqueous Agencies in Ancient and Modern Eras. Having now concluded our descriptions of the strata and aqueous products recognized in the crust of the globe, and also traced the effects of subsequent extraordinary inundations upon the surface, arising from local changes of level or general internal convulsions, it remains to be seen whether the causes now in action in the modern economy of nature are of the same kind as those which were formerly concerned in producing the arrangements and disarrangements ob- served in the crust of the globe. This is the true cardinal point of theory. According as the one or the other conclusion on this point be adopted, we may attempt to explain the ancient phenomena by modern laws of nature, and thus connect the present and the past, the extinct and the existing history of our planet into one system of progressive change, according to the school of Hutton, Playfair, and Lyell ; or suppose that in the chaotic infancy of our planet, laws peculiar to that period prevailed, and properties of matter were unfolded then which never show them- selves at present ; and that the ancient rocks and organic bodies belong to a wholly distinct set of causes, were the produce of a peculiar creative impulse, no longer permitted to operate on the finished and man-inhabited planet. The Wernerian cosmogony bears very much this aspect. But though, put thus in direct opposition, the rival hypotheses appear to have no point of union, we find, in fact, that between the opinion of Hutton, who considers creative nature to be perpetually in progress, the same to-day, yesterday, and for ever and the dogma of Werner, that the world was made by a certain settled sequence of events, to which nothing similar now happens, every variety of theory is adopted and defended. We may, however, with rigid accuracy and much convenience, rank them in three classes. 1. The favourers of Button's and Lyell's views, who maintain that the causes now in action to change the level and alter the relations of the masses of matter in and near the crust of our globe, are those which have ever been in action, identical in kind, and equal in degree, in all times past, and which may be expected to continue the same, in kind and degree, through the future. 2. views of the English School on this Subject The general school of English geologists, who have always maintained, and laboured to OPINIONS Or THE ENGLISH SCHOOL. 467 prove, that the causes operating on the surface and in the interior of the earth have remained through all times past unchanged in kind, and are still operating with the same tendencies as they always did, but often on smaller areas, and with less effect. This view of the subject has a double aspect. English geologists have generally believed that as volcanos were supposed to become languid through want of fuel, the circumstances under which the modern operations of water and fire are manifested in the general economy of nature, approach more nearly a state of equilibrium or saturation, and therefore afford no opportunity for the same extraordinary display of energy as in ancient times ; but since the relative periods of the great convulsions which have elevated chains of mountains, and given new boundaries to the ocean have been investigated upon sound principles, the mind has become gradually familiarized to another notion, and habituated to contemplate long periods of ordinary and regular action of natural causes, interrupted by transient, local, or general convulsions. Ac- cording to this modification of the hypothesis, the present is a period of ordinary and regular action, succeeding upon an epoch of violent disturbance. 3. The old notion of despairing speculators in cosmogony, who found it easier to cut the Gordian knot, by flatly denying the analogy of modern and ancient operations, and either referring the whole beautiful order of the ancient works of nature which they could not comprehend, to a momentary fiat of Deity, or to the rude and pro- longed confusion of elements in chaos. This is the only notice we shall take of that mere dream of indolence and deficient observation ; for we have already proved that the stra- tified rocks are certainly analogous in all points to the products of modern waters, and that the unstratified rocks clearly prove their special origin from fire. As in our accounts of the construction of the earth's crust we have resolved to separate the results of the ancient operations of fire and water, so in our views of the modern effects of these agents, the same plan will be followed ; and, without stopping at every point to settle the precise amount of inference due to every datum, we shall present a connected view of the continual effects of the atmosphere, rains, springs, rivers, and the sea, on the surface of the globe, before pro- ceeding to the changes occasioned by more occasional eruptions of igneous agents from below, volcanos and earthquakes, and other con- nected phenomena. Some general inferences, suited to the present state of the science, may occasionally be ventured, and perhaps many years must pass before any one acquainted with the peculiar tempta- tions to insecure hypothesis which sciences of observation hold out, will venture to dignify his imperfect generalizations with the flattering title of a theory of the earth. 468 MODEE1ST CAUSES IN ACTION. Wasting Effects of the Atmosphere. The gradual wasting of the surface of the higher parts of the earth is an important element in geological theory, and it is scarcely to be supposed that any geologist can be so entirely engrossed with the contemplation of the ancient operations of water in producing the stratified crust of our planet as to neglect the consideration of the analogous effects which are in progress at the present time. The following examples of the varied effects of atmospheric influences, in modifying the surface of the erections of man and the works of nature, are derived from the writer's own observations, and it is to be supposed that they form but a small part of the current informa- tion on the subject. The wasting effects of the atmosphere are those initial or prepara- tory processes by which earthy materials are provided for rivers and the sea to transport and deposit in new situations. These processes, as far as they depend on the atmosphere, are chemical when the atomic composition and the properties of the parts are changed, mechanical when their state of aggregation is altered; and this may happen by general humidity, variations of moisture, variations of temperature, or precipitations of rain. It is not, however, always possible to distinguish accurately the effects of these several causes. Many natural agencies are often concerned in one operation, and the general result is the sum or the difference of their effects. The chemical effects of the atmosphere are evident in buildings and on the surface of certain rocks. The same process which slowly reconverts the mortar of walls into car- bonate of lime frequently causes the pulverization and bursting of the bricks, in consequence of the expansion of the small masses of lime which they contain. The surface of bricks is often covered with a saline efflorescence, which is generally nitrate of lime, but sometimes muriate of soda. The surface of the yellow limestone near Doncaster is sometimes covered with a nitrous efflorescence, and so is the calcareo-magnesian mortar made from it. waste of Felspathic Rocks. The exterior of most uncrystalline rocks and buildings seems to be slowly eaten away by the moisture and carbonic acid of the air ; but the influence of this destructive agent is most remarkable among the felspathic rocks, whether like granite they are originally crystalline, or like millstone grit com- posed of fragmented masses. The felspathic portion of the hyper- sthene rocks of Carrock Fell is so wasted that the crystals of hyper- sthene and magnetic iron are projected from the surface considerably Some greenstone dikes are thus entirely decomposed to great depths from the surface, and whole rocks of granite, secretly rotten, wait WASTING EFFECTS OF THE ATMOSPHEEE. 469 only for an earthquake or a water-spout to be entirely reduced to fragments. Those who have seen the crumbled granite of Muncaster Fell in Cumberland, or Castle Abhol in Arran, surrounded by heaps of its disintegrated ingredients, must have been struck by the im- portance of this phenomenon in reasonings concerning the origin of many stratified rocks. Both carbonic acid and oxygen act very decidedly upon the metal- lic, and particularly the ferruginous ingredients of rocks, and thus swell and burst them to pieces. Sometimes, however, this very cause seems to harden and bind together the rock, and to render it more durable ; and in general there is no certain test of the durability of any stone but experience under the same circumstances. The Bath stone, so permanent amongst its native hills, perishes in the salt air of Norfolk, and few calcareous freestones of any kind will long resist the carbonaceous atmosphere of London. 343 Balkan. Preserving Power of the O round. It IS worthy Ot remark, that sculptured stones buried under ground are perfectly and even won- derfully preserved, while their fellows left exposed to the sky have been almost crumbled to dust. A fine example of this was noticed in the course of the excavations for the Yorkshire Museum, by which the statues which once stood between the arches of the nave of St. Mary's Abbey were discovered, some with blue others with red drapery, one with gilded hair, all retaining the most delicate chisel marks. A few yards from them, at the west end of the church which they once adorned, the atmospheric influences have nearly 470 MODERN CAUSES IN ACTION. obliterated a beautifully sculptured wreath of leaves round the door- way, so that antiquaries have doubted whether they were meant to represent the vine or the ivy. Waste from Humidity. Frequently, in looking at buildings com- posed of porous materials, like the Portland stone, or a grit freestone, we observe the parts which are overhung by a ledge, and thus kept in a state of continual shade and dampness, to be more rapidly con- sumed than the projections ; but the parts which hasten soonest to decay are those near the ground. The same rules are exemplified in many remarkable rocks, as, for instance, in the quartzose conglome- rates of the old red sandstone of Monmouthshire and the millstone grit of Brimham Crags in Yorkshire. The " Buckstone," near Mon- mouth, is a huge rock inversely conical, expanded above into a large area, but contracted below by continual waste to a narrow base of attachment. This process, a little further continued, might convert the Buckstone, as probably some of the stones of Brimham have been converted, into a "rocking stone." From Changes of Heat and Moisture. In northern zones the va- riations of beat and moisture are greatest on the south and west fronts of buildings, and in consequence those fronts to our cathedrals decay most rapidly. This is remarkably the case with the grand cathedral of York, built of magnesian limestone, which is in many places quite consumed on these fronts, but comparatively uninjured on the northern face. The weathering of the surfaces of buildings by the fluctuations of heat and moisture is partly dependent on the structure and composi- tion of the stone. The flagstone of Yorkshire is in many houses at Bradford gradually decayed grain by grain, so that the surfaces of the stone, continually renewed, and never permitting the growth of lichens, appear always neat and clean. The magnesian limestone of the same county, often traversed by veins of calcareous spar, presents frequently a cellular or honeycomb appearance, in consequence of the projection of these veins above the excavated limestone ; but the coarse shelly beds of the Northamptonshire oolites, and the irregu- larly laminated millstone grit, are decomposed in lines corresponding to the inequalities in the composition of the stone. In these cases the stone appears to undergo gradual and continual waste, but sometimes the whole surface exfoliates. Basalt very fre- quently suffers this kind of waste, granite not seldom ; and it has been supposed in these instances, that the atmospheric action merely discloses the latent concretionary structure of the rocks. The following examples require a different explanation. The bridge over the Wear, beneath the western towers of Durham cathe- dral, built (about 60 years ago ?) of a sandstone associated with coal, is ornamented with a balustrade, and the little pillars are worked WASTING EFFECTS OE THE ATMOSPHEEE. 471 with various swellings and mouldings. In crossing this bridge many years since, the writer struck one of the balusters with his hammer, and being much surprised with the hollow noise which ensued, stopped to ascertain the cause. It was found, in many instances, that a thin, external coat of stone, parallel to the mouldings, was entirety separated from the internal nucleus, and ready to scale off* upon the slightest blow. The western front of the ancient and beau- tiful little church of Skelton, near York, built of magnesian limestone, shows the same kind of decay in a direction across the bed of the stone. The Yorkshire flagstone is occasionally used to make curb stones of two feet in height, the lamina) being placed vertically, and the block worked above to a semi-ellipsoidal figure. Even these laminated stones frequently exfoliate parallel to the tooled surface. The ramparts of Zurich are built of sandstone, belonging to the ter- tiary system (molasse), and the stones are cut with a boss along the middle and a depressed border. Desquamation happens parallel to the artificial surface. Since, in these various instances, desquamations are found to occur parallel to the surface, without reference to the internal lamination of the stone, the mere circumstance of exfoliation seems insufficient to demonstrate the originally concretionary structure of basalt and granite. It is, nevertheless, very probable on other grounds, that basaltic pillars, if permitted to assume their natural shapes, without pressing one against another, would resemble a number of super- imposed spheroids. All the cases of desquamation seem to arise from an alteration of the degree of coherence of the stone, whereby the external crust is made to expand and contract differently from the internal parts, and, in consequence, is soon separated from them. The surface of stories long exposed to the weather is frequently much indurated, while the inner parts remain soft. (This is the case in the outer circle of Stonehenge. W. Smith.) From Frost. Frost is likewise an important agent in reducing to smaller masses the materials of the earth. Some stone, if brought to the suface in winter full of its " quarry water," will break in pieces directly. Advantage is taken of this circumstance by the slate-workers of Stonesfield and Colly weston, who quarry their stone in the winter, taking care to shield it from the sun and the wind till the frost has acted upon it, with the aid of affused water, if necessary, which, by disclosing the natural fissility of the stone, permit the blocks to be cleft into thin, sound, roofing slate. Landslips in moun- tainous regions are, probably, much accelerated by the power of frosts. In ascending the Righi from Weggis, on the Lake of Lucern, we are much struck by the extraordinary length and continuity of the joints of the niigelflue. It is from these natural partings that 472 MODEKN CAUSES IN ACTION. the landslips fall, when repeated rains, snows, and frosts have worn or burst them open, and the water passing down them undermines the foundation of the cliff. Thus huge blocks, liberated from their attachments, roll down the steep descent, or half the summit of a mountain slides upon its argillaceous bed. Vast portions have thus slipped from the Bighi towards the isthmus which divides the lakes of Zug and Lucern, and others are preparing to follow. The fissure is already opened parallel to the edge of the precipice, and pervious below, so that a stone thrown in at the top, is said to fly bounding out at the base. Effects of Rain. We come now to the effects of rain, and without dwelling on the general degradation of the softer surfaces of the earth caused by this agent, we shall proceed to show, that within the historic era hard and durable stones have been greatly furrowed by the rain, and that in more ancient periods, the precipitations from above have carved themselves channels of various kinds, and sometimes oc- casioned real though miniature valleys of great length and continuity. On Monumental stones, &c. Many Druidical monuments in the north of England are constructed of coarse millstone grit, a rock admirably suited for yielding those enormous blocks preferred by the ancient architects. Three huge Druidical stones, now standing near Boroughbridge, called the " Devil's Arrows," present us with a most instructive lesson on the ultimate fate of all human erections exposed to the ravages of time. The rain, beating for 2,000 years upon these venerable pillars, has cleft their tops, and ploughed deep furrows down their sides. The grooves are deepest at the top, and become wider and less distinct towards the bottom ; they cross indifferently the false-bedded layers of pebbles, and go directly downwards. One of the stones leans re- markably and threatens to fall, but an examination of the furrows shows the inclination to be of most ancient date, for they descend much farther down the pillar on the upper inclined face than on the under. Similar effects of rain are visible to a greater extent on the bold crags, like Almias cliff and Brimham rocks, which crown the sum- mits of so many hills of north-western Yorkshire, from some of which the Devil's Arrows were obtained. In the valleys of Switzerland (Sarnen) blocks of limestone, which have fallen from the mountain sides, have been furrowed in the same way since their descent. On Rocky cliffs and Floors. The carboniferous limestone of England has been little employed in building, except partially in old castles, where it seems durable, and they who know the magnificent ranges of scars which begird the hills of Derbyshire and Westmore- land will acknowledge that few rocks seem more likely to endure the rage of the elements. But yet close inspection of these giant cliffs WASTING EFFECTS OF THE ATHOSPHEBE. 473 will prove that time has been busy there. The dry and bleached aspect, and the smoothed angles, show plainly the wasted surface. Those who have stood on Doward Hill, near Monmouth, to contem- plate the rain-furrowed white limestone there, will not need another example. In the north of England analogous and more remarkable instances present themselves in the wide limestone base of Ingle- borough, and in Hutton roof crags near Kirkby Lonsdale. The vast limestone floor which supports the cone of Ingleborough is marked in all directions by natural fissures, and divided into com- partments like a map. If one of these compartments be examined in the western part of the mountain, its surface will be found scooped into little hollows which unite into a common channel, and terminate by indenting the edges and furrowing the sides of the fissure. They are, in truth, valleys in miniature, separately produced, by the drainage, so to speak, of the several blocks. The mere decomposing effect of the atmosphere produces on the edges of the stone a different effect, by wearing away the softer laminae, but the smooth surface of the miniature valleys, their regu- lar descent, winding course, and union into a common channel, show that they were fashioned by the repeated operation of descending rain. This scar is nearly level, but in Hutton roof crags we have an opportunity of tracing the rain channels over an immense surface of bare limestone rocks lying nearly level on the hill top, but sloping rapidly down the sides to the east and south. On the level top of the hill the stones are variously worn in hollows and grooves irregu- larly united and running in different directions, according to little variations of the ground ; but on the steep east and south slopes the channels are extended into long furrows, which, uniting at acute angles, enlarge, widen, and descend the hill side, in lines following ex- actly the declination of the rocks, and stopped only by the few and dis- tant fissures beyond which other systems of concurrent grooves begin. Bain Channels like Miniature Valleys. It IS impossible by draw- ings, or descriptions, to convey such an idea of the appearances of the Hutton roof crags, as to awaken in others the deep impressions which are fixed for ever in the mind of the observer. The astonish- ing resemblance which these little ram. channels present to the great system of valleys which undulate the stratified rocks, seizes upon the imagination, and we re-examine all our notions of the origin of these great undulations. The fissures in the limestone rocks which stop and swallow up the gathered streams, are analogous to those longi- tudinal valleys beneath the escarpments of the oolites, and the chalk by which the rivers are turned at right angles to their earlier course, while the lower edge of the fissure corresponds to the escarpment itself, with its new system of denudations. 474 MODERN CAUSES IN ACTION. To see these rain and time-ploughed furrows winding in uncertain directions over the horizontal limestones on the hill top, like a slow river in a level plain, but running a straight downward course on the slopes, like a stream descending irom its parent mountains, is enough to impress on every beholder a secure conviction that the excavation of valleys must be explained upon similar principles ; that, as the feeble currents of descending rain, aided by long time, have been sufficient to plough their little courses, so the greater action of existing streams has been sufficient to work out their actual channels, though the excavation of the broad valleys in which they run, may have been accomplished by more violent and voluminous waters, flow- ing in directions predetermined by ancient subterranean movements. Effects of inundations. It is probable that the slow but incessant action of rain, beating perpetually on the hard and the soft surface of the earth, and removing grain by the materials loosened by the expansive agency of frost, moisture, and chemical changes, may be, in a given long series of years, more important in its effects than the violent water-spout, or the ravaging inundation of a bursting lake. Yet the effects of water-spouts are tremendous in countries composed of easily destructible or unequally indurated materials. A water- spout which fell on the mass above Kettlewell in Yorkshire, commit- ted the most terrible ravages in the narrow valley of the Wharfe, near Kettlewell and Starbottom. On the sides of the mountains in Cumberland, traces of these visitations seem utterly ineffaceable ; and the memory of the sudden bursting of the Peat Bog above Keighley, will long be preserved in the valley of the Aire. The floods which rushed simultaneously from the Cairn Gorum and other mountains, in August 1829, over 5,000 square miles of Aberdeenshire and other counties, were of prodigious fury, removing hundreds of tons of large stones, whole acres of woodland, and almost hills of earth. The desolating effects of the bursting of the ice-dam which had formed the temporary Lake of Bagnes, are matters of history. The moving mass of water, mud, and monstrous rocks, which swept with violence down the valley of the Dranse, carried away forests, houses, bridges, cattle, and men. In six hours and a-half it passed through an unequal and irregular course of forty-five miles, till its waves were lost in the Lake of Geneva. Glaciers are likewise to be enumerated among the powerful agents by which the higher lands are wasted, and materials provided for the raising of the lower. As the summer heat melts every year the lower portions of these long winding rivers of ice, and the heated ground thaws, and the gathering water dissolves their foundation, the whole might}' mass of snowy ice slides downwards on its failing bed, ploughs up the stones, breaks up the rocks, and adding their spoils to the accumulations of the avalanches, throws to the sides EFFECTS OF INUNDATIONS. 475 huge banks of rubbish, provincially called moraine. The foot of the glacier is thus surrounded by an immense hill of loose materials which gradually find their way into the stream that issues beneath. 344 Track of a Glacier, Mer de Glace. Descending Streams and Rivers. The wasting effects of the atmosphere, noticed in the preceding section, are sensible in all regions, and therefore in every country some materials are provided for the streams to transport. But the proportion of matter thus prepared in mountainous countries is so vastly greater than elsewhere, that in general the less conspicuous effects of the same causes in lower regions are overlooked. The common notion respecting the action of alpine streams appears to 476 MODERN CAUSES IN ACTION. be, that these are the principal agents of destruction upon the faces of the mountains, and that it is to them that the actual waste of the surface is attributed. But though these streams are indeed powerful agents of excavation, their principal influence is of quite another kind, and it is chiefly by the disposition of the materials brought into them by rains, avalanches, and water-spouts, that they effect such important changes. Erosive or Excavating Action of Streams. In considering the action of streams and rivers, we must distinguish between their powers of eroding or excavating, and of transporting solid matter. The former is occupied on the channel and flood way, and its effects have relation to the consolidation of the matter traversed, and to the rapidity and volume of the moving water. About their sources, and for a long part of their early course, streams deepen continually their channels, and wear away their barriers of rock : but in their broad expansions near the sea, this power of excavation wholly ceases, as a general law, and is only evinced in particular cases, as when great bands are cut off or banks are undermined. We have abundance of examples in all our mountain regions of the actual excavation of their channels by the rivulets and rivers. In the district of Aldstone Moor, the south Tyne runs to the north from the side of Cross Fell, for some miles along a slope of shale, over the Tyne bottom limestone. In this shale, which is itself excavated into a broad valley, the river has evidently cut its own narrow yet sufficient channel ; and no contrast can be more striking than that here afforded by the mighty valley of Tynedale, 1,500 or 2,000 feet below its bordering mountains, and the little channel holding the waters of the River Tyne. Every river in this manner works out its own channel in elevated regions, and in lower ground the soft clays and sands yield a passage to the feebler currents. In the level regions, along the rivers of Yorkshire and Lincolnshire, the channels have been many times changed, even by those sluggish streams, and still more in the deltas of the Rhine, the Nile, and the Mississippi ; and among the Alps, this fluctuation of the river courses is exces- sively irregular. No doubt, then, can remain of the fact that rivers and running waters excavate and alter their channels. Lyell has given a remarkable case of the recent excavation in a bed of modern lava of a channel from 50 to several hundred feet wide, and 40 to 50 feet deep, by the river Simeto, flowing from Etna. Scrope has also shown similar phenomena to have happened in the volcanic region of Auvergne. In these cases the action of the river has probably been excited by the flowing of a current of lava across its course, so as to dam up the waters, and give them something of the force of a cataract. Waterfalls, &c. The waterfalls and cataracts upon the line of a EEOSIVE ACTION OE STEEAMS. 477 stream afford some curious points of study. It is especially in these cases that the increase of excavating power, derived by a river from the solid matter which it transports, is most sensible. A cataract is formed upon the river Eden, in Westmoreland, near Kirkby Stephen, by some remarkable beds of calcareous red sand- stone conglomerate, and the pebbles which the river brings down, here contribute with the whirlings of the water to excavate many deep perpendicular pits, similar on a small scale to swallow holes on the mountain limestone ranges, or those romantic cavities on the Caldew in Cumberland. Below many waterfalls in Wales and Scot- land, the same effect is produced. 345 Deposit of Travestin at a Cascade. But the most characteristic effect of a cascade, is that ceaseless undermining of its base and sides, and consequent rupture of the spout or edge of the fall, which causes by slow degrees the cascade to retire farther and farther up the mountain side, and produces those awful and still deepening portals of impending rocks, which so much aggrandize the sublimity of a noble waterforce. (In Norway, fan.) This effect may be excellently observed in the carboniferous lime- stone district of the north of England, where so many beautiful streams leap from the beds of limestone over perishing shales and sandstones, and rising in foam sap and undermine the base of a large semicircular cliff, till at length the solid limestone crown gives way, and the insatiable river renews its destroying attacks. The same thing is seen in many of the Swiss waterfalls, particularly in the manifold falls of the Giessbach. Lyell very ingeniously applies the acknowledged fact of the reces- sion of the Falls of Niagara, which appear to have been pushed back several miles, at the rate of 40 or 50 yards in 50 years, to the pos- 478 MODERN CAUSES IN ACTION. sible discharge hereafter, through the St. Lawrence, of the waters of Lake Erie. Such a discharge would, of course, occasion a local deluge ; but the lake is so rapidly filled up by sediment, that it is a question whether it will not become dry ground, before the falls of Niagara shall have been pushed back so far as to be capable of emptying it. The fall of the Rhine at Schaffhausen is a grand exhibition of the erosive power of water, particularly the wearing of the base of the two island pinnacles of limestone, which now stand proudly in the midst of the currents, but will eventually be hurled down the thundering cataracts. 346 Falls of Niagara. Transporting Power of Streams. In considering now the trans- porting action of streams, we may distinguish between such as flow through valleys of uniform declivity without lakes, and such as pass through broad receptacles of water, before arriving at the sea. As examples of the former, we may take many rivers of England ; for the latter case, several rivers of England, Wales, and Scotland might be named, but much grander phenomena of the kind are witnessed among the streams which flow down from the snow-crested Alps. Rivers without Lakes. A certain velocity of current is requisite for the transport of every kind of earthy matter; the finer the matter the less force will move it along. Hence in the lower parts of rivers, where their course relents, and they approach the sea, though they can no longer, as in their youthful energy, remove rocks and transport loads of sediment, their waters are muddy, and their channels and sides receive continual augmentation. Such a river as the Yorkshire Ouse is very instructive. As its branches descend from Shunnor Fell, Cam Fell, and Whernside, they transport daily TRANSPORTING POWER OF STREAMS. 479 and hourly from those elevated sites the materials accumulated by atmospheric changes and mechanical attrition ; the soil, the stones, the loosened rocks, grain by grain, and piece by piece, move onward with the current, and thus the whole mountain, region, by a slow yet not imperceptible progress, is lowered in height, and its wasted spoils swept away for ever. But let us follow this process. Wherever the valley originally presented great inequalities, these are constantly diminished by the upfilling of the hollows, and at length the ori- ginally rugged chasm is changed by additions and upfillings into the smooth, evenly declining hollow, which, because of that smooth- ness and uniform declination, is supposed by many to be entirely a valley of denudation. In this process, the lateral action of rains and inundations from the sides of the valley, is a very important auxiliary. Any one who contemplates the valleys of the Jura, near Schaffhausen, and sees them in many cases rugged on the sides, and evidently traced by nature in a fit of convulsion, must be struck by the smooth, even, equally declining plane of their bottom, which cuts the rude precipices of the sides, and clearly indicates a subsequent powerful modification of the original harshness of the chasm. Still more abundant is the deposit of sediment as the stream glides into lower ground. There, above its narrow channel, rise the broad meads which, with every fresh inundation, receive a new coat of sediment, and above these swell the real boundaries of the valley, often consisting of water-worn materials, gravel and sand, left there by ancient floods of greater power, flowing at a higher level. As we approach the sea, when the tidal currents meet the freshes, the sus- pension of motion permits a great part of what sediment still remains to discolour the water to drop on the bed of the river, and its alluvial banks. Thus the streams become choked, their channels sinuous, their beds elevated, and the banks which confine the river, heightened both by nature and art, look like the ramparts and ter- races of a lofty military road rather than the boundaries of a river giving passage to the drainage of the neighbouring country. The same process at the mouths of rivers pushes their channel and their banks outwards into a cape or headland, and contributes to extend the whole breadth of the bordering coast, so that by the waste of the uplands the low land is filled up, the river channels are raised, the coast is extended into the sea, and the sea filled with shoals and sand banks. Thus the mouths of the Po, the Rhine, the Nile, the Euphrates, the Ganges, and the Mississippi, have formed for themselves those broad deltas which, within the historic era, have transformed ancient ports into inland towns, and carried fertile pas- tures into the area of the sea. The substances transported by the stream, and deposited along its sides, are of course such as the hills around its sources, and above 480 MODEEN CAUSES IN ACTION. its channel, furnish ; and according to the nature of the country, the almost incessant accumulations of earthy matter which thus take place, may be varied by the interposed layers of vegetable reliquise. In tropical and warm regions, and in unenclosed countries, this must be the case to a far greater extent than an acquaintance with Euro- pean rivers would lead us to expect. The mighty forests of America, untouched by human industry, must annually furnish to the great rivers which intersect them, an immense spoil of trees, which being easily supported by the current, will be carried even to the sea, and either deposited at the river mouth, or drifted away on the waves. Arrangement of materials. The arrangement of the materials brought down by the streams is in general regulated by a tendency to the production of a level surface, and thus the original inequalities of a valley are continually lessened. In a high region like the Alps, the rough streams leave in the higher level chiefly a collection of pebbles and sand, and they are left in much local confusion ; but still the general effect is a uniformly declining plane, through which the capricious stream finds itself new channels, and thus continually shifts its deposits over the whole, broad, pebbly surface. Such effects may be well seen on the line of the Arve, as it hurries down from the glaciers of Savoy. On the contrary, in the lower and more level expansions of a valley, where the gentler waters transport only fine sediment and vegetable reliquiae, these materials are arranged in most exact parallelism over a large extent of plane surface, and by counting the laminaB of deposition, some useful notion may be formed of the period occupied in the process. On the borders of streams which are periodically swollen by rain, as in the tropical regions, or by the melting of snows, as in those which descend from high moun- tain countries, this mode of computation of the laminae may even be trusted so far as to determine the number of years employed in pro- ducing a given depth of deposit ; and even in districts where the rivers swell irregularly at uncertain intervals, there might be an average rule for the same purpose deduced. Nor would the accumu- lation of a short period of time, tried by this test, appear inconsider- able. In a single season, the rivers of Yorkshire, aided by the sea, deposit many inches of rich soil upon the level peat moors which adjoin their estuary ; and at Ferrybridge, at the point where the tide, formerly flowing up the river, neutralized the freshes of that river, many of the modern works of man, as oars of a boat, a coin of England, were found buried under the alluvial sediment, which con- tained petrified hazel branches and nuts, bones of the stag, &c. From what has been said of the action of rivers, it is evident that their effects upon the physical features of a country are more varied and interesting than has been generally perceived by those who have written on the much controverted question of the origin of valleys. EIVEE DEPOSITS. 481 The tendency of all descending streams of water is the same, to equalize the surface of the earth, to remove all its ridges and asperi- ties, and to smooth all its gulfs and fissures. The degree in which they respectively perform this depends, first, on the amount of atmospheric and local influences in wasting the surface of the higher ground, and bringing materials for the rivers to act upon. Hence the rapid waste of high Alpine tracts exposed to fluctuating heat and cold, to storms, avalanches, and glaciers. Hence the streams of sand and pebbles, which rush from the grit- stone hills of England, and, on the contrary, the almost unsullied purity of the springs which break from the carboniferous limestone. The second circumstance which determines the modifying power of the river is its own volume and velocity, and these are principally dependent on the physical geography of the region. The datum of the volume of water flowing in any valley is principally useful for comparison with the amount of effects ; the kind of effect produced is determined by the velocity of the current. If we conceive that in its first fury a river may have power enough to sweep along even large blocks of stone, but that its velocity gra- dually diminishes, there will be a certain point, where these large blocks will be left by the enfeebled current, pebbles will roll farther, coarse sand will travel beyond, and the finer sediment will be moved on till the languid waters permit their slow and equal deposition. This gradation of deposits is always observed in examining valleys of sufficient length and elevations. The deposits in the upper parts are tumultuous and confused, in the lower regions level and regular. A third circumstance, of still more importance than the others, serves to regulate the action of the river. This is the form and character of the valley itself. However produced, there can be no question that the present aspect of almost every valley in the world is smoother and more equalized than it was formerly, since we see evidently and take as a principle, that the characteristic effect of modern causes in action is to reduce continually the inequality which remains. We may, therefore, easily, for each valley, restore in ima- gination its ancient condition, remove the sediment from its expanded meadows, and leave, instead of level or gently sloping plains, that wind smoothly round the hills, and ascend far up toward the sources of the stream, deep chasms between cliffs rent asunder by convulsion, and ridges of rock confusedly crossing the gulfs of the strata. That such has been the origin of many valleys is perfectly evident. That these may have been partly cleared, and others wholly occasioned by violent floods, sweeping over and denudating the land during its elevation from the sea, or by some violent catas- trophe at a subsequent period, is also very probable, or rather may 2i 482 MODEEff CAUSES IN ACTION. be considered as proved. But without entering on these questions, we may content ourselves with the datum that the fundamental fea- tures of valleys are not the result of the excavating action of their streams, but that valleys have been in part filled up by the accumu- lations brought by their own rivers, and that their present smooth- ness and uniformity is really the result of the modifying powers of the sea, the atmosphere, local influences, and the river, exerted through long time upon a ruder channel, left by more violent and transitory agents. Rivera with Lakes. Let us now see what peculiarities in the effects of rivers are occasioned by the circumstance of their traversing quiet lakes. Two things are here to be attended to. First, the lake causes, according to its extent, a more complete deposition of the sediment brought by the rivers than is occasioned by the most level dry area of a valley ; secondly, the materials dropped in the lake are regulated by somewhat different laws from those which direct their accumulation on the common surface. When a river charged with sediment expands into the waters of a lake, its motion, communicated to that large area in directions radiating from the place of entry, relents, and is almost lost, and the sediment which it brought is gradually, and at last wholly, deposited in the lake, whose transparency it disturbs, and the purified stream issues from the lower extremity without a single taint of its stormy origin, unless it be the colour, of the mountain-peat, or some other substance held in chemical solution. Like the lake from which it escapes, or the ocean far from shore, it generally assumes the purest ethereal hue, its native tint of green or blue, but soon in its onward course it again becomes turbid with sediment. Every lake in Swit- zerland exhibits these pleasing effects upon the rivers, which com- monly enter in turbid violence, and issue of a lovely transparent green, but the Rhone is pre-eminently blue. These lakes are filling and contracting at their upper ends with the sediment which they filter from the rivers, and the process, though historically slow, is monumentally impressive, since we perceive large tracts of level meadows cultivated, covered with trees, and adorned by ancient and modern towns, where formerly flowed the deep waters of the lake. All this new land was formed from the spoils and waste of the upper countries drained by the river, and it is an exact measure of the whole effect of the atmospheric and local influences in weathering the face of the hills, and of the rivers in transporting away the materials thus prepared for them from the earliest period when the streams began to flow down the actual valley. Arrangement of Materials. The second thing to be attended to in considering the effects of lakes on the line of rivers, is the arrange- ment of the materials which they receive. This is a subject in which EIYEE DEPOSITS AEEANGEMENT OF. 483 Mr. Yates's observations* will be found useful. It is known to practical men that loose earth will remain at rest if it be placed at an angle, not exceeding 45 with the horizon, and when loose, earthy materials are poured from a height, they usually arrange themselves in a conical heap, whose sides make nearly this angle with the horizon. On the slopes of mountains liable to avalanches or rapid waste, the loose debris is usually found in a plane declining at about this angle. When streams falling over an edge, pour with their waters a quantity of earthy matter, the conical heap so produced is very much more obtuse than when the materials fall dry, and the larger the propor- tion of water that comes down, and the more forcibly it descends, the flatter is the slope of the cone. This will easily be understood upon the principle that by partial suspension in water each particle is influenced by the tendency of that fluid to become level. It is easy to understand from this that the form in which coarse sediment will be deposited by rivers entering a lake, must be in a very obtuse cone radiating round the point of entrance. As the heap of sediment is advanced into the lake by continual additions, its outline remains circular, with a larger radius, and its section will be nearly level toward the land, but sloping more and more rapidly toward the interior of the lake. Were the particles to be arranged in obedience to the double forces of horizontal movement with the river, and of perpendicular descent from gravitation, the curve of the edge would be parabolic, and the surface left upon the sediment toward the land nearly level. But the earthy matter being unable to support itself at more than a certain angle of elevation, the lower part of the curve will become less steep, and be reduced to a straight line. Mr. Yates's observations on the Swiss lakes led him to assign to the sediment left therein an outline of this kind. It is obvious that in these cases the sloping layers nearest the entrance of the stream are of older date than those farther advanced into the lake. It is an interesting subject of inquiry to learn whether, as is most probable, the particles of the sediment which differ in bulk and specific gravity, are arranged according to those qualities so as to constitute horizontal strata, of finer and coarser matter, &c. ; and whether, this being the case, the sloping lines of deposition, &c. are visible or obliterated in the section. In this manner the upper ends of lakes are filled with the deposits from the rivers almost to the surface ; and, the dams of the lower ends of the lakes being worn away by the incessant action of the stream, these deposits become visible above the water, and constitute those smoothly declining, often moist surfaces, which usually confine within their indefinite border the * Edinburgh Journal, 1831. ' 484 MODEKN CAUSES IN ACTION. shallow and weedy waters destined in their turn to retreat from the desiccated land. While this process proceeds near the shore with the coarser particles, it is obvious that the finer sediment will be carried farther into the lake, and be spread more widely over its general bed. These remarks apply only to deep lakes, whose waters rest tran- quilly on their beds, and are only agitated at the surface. In shallow lakes, which are agitated to the bottom, the materials must neces- sarily be distributed in planes very nearly horizontal, in consequence of the impressions from the fluctuations of the surface. This is matter of daily observation. Lacustrine Deposits. Before we dismiss the subject of lakes, it will be proper to take notice of another process tending also to fill them with new deposits. -Many streams which enter lakes carry along, dissolved in their waters, a quantity of carbonate of lime, which may afterwards, by the loss of carbonic acid from the water, fall in calcareous sediment, and constitute beds of marl, or by the slow absorption of mollusca be converted to shells. In the latter case, beds of limnaea}, paludinse, &c. are formed, and as, generally, the light argillaceous sediment entering such lakes is pretty equally diffused through the waters, the result is a bed of marly clay full of fresh water shells. This process is daily going on, and in the course of a few years canals and river courses, as well as ditches and ponds, are choked by the abundant accumulation. In this manner, aided by occasional inundations, bringing layers of vegetable matter, or the detritus of the neighbouring country, have many old lakes become entirely filled up, and when cut open for any purpose, present layers of peat, clay, shell, marl, and sand, a faithful image, on a small scale, of those great fresh water deposits which mark the force and extent of ancient currents on the surface of the earth. , Deltas. The delivery of the sediment of rivers into quiet, tideless, land-locked seas is almost perfectly analogous to what happens in a large lake, but according to variation of circumstances, as the river flows into the open ocean, and contends with strong tides and sweep- ing currents, or disembogues itself into a gulf, enters deep or shallow water, the disposition of its sediment is different. The most remark- able deltas at the mouths of rivers are formed round such as empty themselves into tideless seas, as the Mediterranean, Black Sea, Caspian, Baltic, &c., or into comparatively quiet bays of the ocean, as the Bay of Bengal, the Grulf of Mexico ; and the least effects of this nature are occasioned on coasts which are subject to be raked by lateral currents of the sea. Most of the great rivers which enter the Mediterranean are daily increasing their deposits along the coasts, and spreading a quantity of sediment over the general bed of the sea. The Mediterranean GULFS, ESTTJAEIES, ETC. DEPOSITS TN. 485 has been proved by a line of soundings on the Skerki shoal from the African to the Sicilian coast, varying unequally from 7 to 91 fathoms, to be divided into two basins. In the western portion, near Gib- raltar, the bottom, consisting of sand and shells, has been reached at 5,880 feet, and in the straits at 4,200 feet. Almost under the shore at Nice the depth is 2,000 feet ; but in the Adriatic, where it receives the sediment of the Po and other rivers, in the upper part, the greatest depth is 22 fathoms. Yet from the abrupt borders of the hill ground within the area of the sedimentary land, it is inferred that the Adriatic must formerly have been a deep gulf. Nature of the Deposits in Gulfs, Estuaries, &c. Farther from the influence of the rivers the depth increases considerably. Donati, on dredging the bottom of the shallow portion of the Adriatic, found it to consist partly of mud, and partly of calcareous rock, enclosing shells, which are sometimes grouped in families. (Lyell.) The form of these sedimentary deposits must be what in common lan- guage is called horizontal, the substance of them fine clay and cal- careous matter with shells ; and as the ratio of accumulation is nearly uniform, there will be little appearance of strata, unless the calca- reous deposits be accomplished at intervals. If by any effort of subterranean forces this bed of the Adriatic should hereafter be ele- vated and made dry land, as so many other extensive tracts along the borders of the Mediterranean have been, we should have an argillaceous deposit extremely similar to the London clay, and per- haps identical with the subapennine marls, except by some difference of organic remains, and of such an extent as would appear incredible to those who believe in the almost quiet slumber in modern times of the mechanical and chemical forces which belong to our globe. The same conclusions might be derived from an examination of the mouths of the Rhone, Volga, Danube, Granges, Euphrates, &c., which enter the sea under the same favourable circumstances, and trans- port enormous quantities of fine sediment into comparatively tran- quil and now shallow waters. A river like the Mississippi, which hurries an enormous volume of deep waters, and preserves its velocity to the edge of the sea, discharges likewise a prodigious quantity of matter, which settles round its many mouths into a vast and growing delta. But the kind of matter here deposited and the mode of its arrangement will be different. Forests matted together by the growth of ages, with all their foundations, their alligators, and other , inhabitants, are swept down by this mighty stream, and either retarded for a time among its winding and variable channels, or hurried into the sea, and there, with quantities of similar matter, agitated, and partially or completely separated into beds of earthy and vegetable matter, the latter varying according to the prevalence of the many rivers which unite in the great stream, and thus the 486 MODEEN CAUSES IN ACTION. gulf of Mexico is now filling with deposits, which in no feeble degree emulate our old carboniferous strata. We are informed by Lyell, whose volumes are full of valuable information on all subjects con- nected with the modern operations of natural agencies, that a great part of the new deposit at the mouth of the Rhone consists of cal- careous and arenaceo-calcareous rock, containing broken shells of existing species ; and Captain Smyth ascertained that over the broad, very gently inclined bed of this growing delta, marine shells were occasionally drifted by a south-west wind. In this way alternations of fresh water and marine shells may be occasioned, in which the marine portions will predominate towards the sea and the fresh water part be most decided toward the land. The shorter and more rapid the course of a river, the larger and coarser is the sediment which it may be able to transport. While the Po, relenting in its velocity, leaves its gravel where it joins the Trebia, west of Piacenza, 130 miles from the sea ; and the Ganges 1 80 miles above the commencement of its delta, and 400 miles above the present line of coast ; the rough bed of the Yorkshire Tees is pebbly quite down to the sea ; and the streams which descend by a short and furious course from the Maritime Alps bear down pebbles into the Mediterranean. From these instructive examples of pebbly, sandy, argillaceous, and calcareous strata, forming at the same era, in different basins of the sea, and even in different parts of the same basin, enveloping entirely marine, entirely fresh water, or a mixture of marine and fresh water deposits, we may turn with advantage and pleasure to the contemplation of the older strata of conglomerate, sandstone, clay, marl, and limestone, and, by carefully noting the points of agreement and circumstances of difference, may frame very satisfac- tory notions of the conditions under which they were deposited respectively. Especially we may be guided in our decision concerning the extent and connection or separation of the several basins of the ancient ocean, and the relative influence of ancient and modern rivers. Bars at the Mouths of Hirers. Rivers which discharge themselves into the sea, where tides and currents contend with the freshes, may, as the Rhine, be enabled for a certain time to deposit their sediment in a delta, and to increase this even to a vast degree, in consequence of their entering at a deep emargination of the coast, or amidst shal- low sands which impede the action of the tide. But in such a case the accretion of land must gradually diminish, and at length the movements of the sea must balance the current of the river. In this case a line of sand-banks will be formed varying in position according to the alternate predominance of the contending forces, and the entrance of the river will have a bar. The Rhine, the Thames, and all the eastern rivers of England are nearly in the same case. The EITEE DEPOSITS FORMATION OP. 487 sea, indeed, has again reclaimed from the Rhine, by most destructive floods, the large spaces of the Zuyder Zee and the Bies Boos. Thus also the growth of the Nilotic delta, once so rapid, is greatly retarded or almost annihilated by a current of the Mediterranean ; and the rivers of western Africa, as well as the mighty Maranon, no longer extend themselves into the sea, but meet its currents in furious strife, drop the sand at their mouths, and resign their finer sediment to the disposal of the conqueror. The distance to which the ocean can waft this sediment on its surface along with fresh water is very great. Colonel Sabine supposes himself to have crossed the discoloured waters of the Maranon 300 miles from its mouth, where it still retained its comparative levity, and kept its place on the surface of the sea. Thus may the sediments of distant countries be mixed or alter- nately deposited far from shore, and even in the deep sea, a fact of great interest to geology. The distinctness of currents of water which flow down the same river channel, even with a rapid descent, has often been noticed. Thus the Arve and the Rhone flow far without mixing, the Nahe takes one side of the Rhine, and even in the mining districts of England, the discoloured streams from the different valleys can often be distinguished along considerable lengths of the united river. We shall not further extend our remarks on this subject than by stating a few instances of the actual surface of the deltas of great rivers. The whole area of the dry delta of the Po and the Adige, and other rivers which contribute to the effect on the same line ' of coast, must exceed 2,000 square miles, and within the last 2,000 years a space of 100 miles in length, and from 2 to 20 miles in breadth, has been added to the land. The area of the Nilotic delta is about 12,000 miles, and according to Grirard the surface of Upper Egypt has been raised by the sediment since the Christian era 6 feet 4 inches ; of the Rhone 1,500 square miles ; of the Quorra 25,000 square miles.* The delta of the Ganges, without reckoning that of the Buram- pootra, which has now become conterminous, is considerably more than double that of the Nile, and its head commences at a distance of 220 miles in a direct line from the sea. The base of this magni- ficent delta is 200 miles in length.f The fen lands of Lincolnshire, Huntingdonshire, and Cambridge- shire occupy 1,000 square miles, and the levels in connection with the Humber 300 or 400. It has been attempted to deduce the age of our continents from the rate of increase of the deltas of rivers within the historic era. Thus * Dr. Fitton, Geology of Hastings. t LyelL 488 MODEEN CAUSES IN ACTION. the Nile was supposed by Herodotus to have formed Lower Egypt ; and he states that if diverted into the Red Sea, it would fill that gulf with its deposits in less than 20,000, or even 10,000 years. Since the time of Herodotus it is supposed that the increase on the Nilotic delta has been upon an average, one mile and a quarter. The average annual growth of the delta of the Po, opposite Adria, which was once on the edge of the Adriatic, was, from 1200 to 1600 A.C., 25 metres, and from 1600 to 1800, 70 metres ; a very rapid increase of rate, probably connected with the increasing shal- lowness of the sea. But all inferences from observations of this nature, and similar ones on the shallowing and conversion to land of the upper ends of lakes, can lead only to merely speculative results without the know- ledge of a datum very difficult to be obtained, viz. the original depth of the sea or lake, at all points over which the river sediment has flowed ; for it is not by the area of the delta, but by the cubic content of the sediment transported that the time occupied in the process is to be ascertained. How is this to be determined ? The Sea. As the action of rivers is of two kinds, erosive and transporting, so is that of the sea. In one place its fury excavates the cliffs, and devours a whole country, in another every tide adds sediment to a growing shore, lengthens the fields, and extends the parishes, till what was once a broad bay becomes a fertile marsh, and the town which was once a flourishing port is far removed from the waves, and never visited by commerce. These different effects de- pend principally upon the circumstances under which the earthy materials are presented to the waters. Cliffs exposed to the sea are either slowly decomposed by its vapours, and crumble piece-meal, or undermined at the base, and so caused to fall in ruinous heaps. Even the hardest rocks that begird the ocean are more or less wasted away by its never-ceasing attacks, conjoined with the common atmos- pherical agents. Soft places are scooped into caverns, joints are widened, and blocks loosened, and thus, by little and little, every high coast recedes and yields more or less ground to the insatiable waves. But cliffs composed alternately of softer and harder strata, especially if there be any dislocation, are quickly eaten away, and still more rapid destruction falls annually on the crumbling diluvial clays and loose gravelly cliffs which margin so great an extent of the coast of England. The whole of the English coast may be cited for cases of this important wasting of the cliffs, and in particular the diluvial cliffs of Yorkshire and Norfolk. In the former county it seems to be ascertained, by careful measurements at many points, repeated after intervals of many years, that the annual loss of land * Lyell, Principles of Geology. SEA ACTION EEOSIYE AND TBANSPOETING. 489 on the whole length of Holderness, is not less than 2J yards in breadth annually. The average loss on the coast of Norfolk be- tween Weyburn and Theringham is about 1 yard per annum, on the coast of Thanet 2 or 3 feet. But these same coasts likewise exhibit, on an equally grand scale, the formation of new land from the materials thus detached from the old. The materials which fall from the cliffs are sorted by the tide, and according to their bulk and weight are differently disposed of. As in many artificial pro- cesses of washing powders the sediment is divided into parts of different fineness by merely shaking it at different distances or depths in the stream of water, so it is in the great currents of the sea. Large stones remain a long time at the foot of the cliff from which they fell, smaller masses yield something to the impetus of the waters, sand and pebbles are drifted along the shore according to the set of the tide, and collected into bays and hollows of the coast, or deposited in a line of moving beach ; but the finer clays are trans- ported far away in the waters, and allowed to settle only where these rest in land-locked gulfs, stagnate over weedy marshes, or lose their force in contest with the freshes. The breadth of the sandy beaches thus accumulated is often very great, even many miles of slow and regular descent. The sand banks which stretch out so far from the low coasts are often regarded as remains of ancient lands overwhelmed by the sea, but in most cases they are probably recent formations, accumulated by the waves from the spoils of other regions. But what is thus left by the sea under some circumstances, may be again reclaimed by it under others. The once fertile district called North Friesland, most probably accumulated by the sea, measuring from nine to eleven geographical miles from north to south, and six to eight from east to west, was in 1240 entirely severed from the con- tinent, and in part overwhelmed. The island of Northstrand, thus formed, was, towards the end of the 16th century, only four geogra- phical miles in circumference, but still was richly cultivated and populous. At last, in 1634, in one night, the llth of October, a flood passed over the whole island, whereby one thousand three hundred houses, with many churches, were lost, fifty thousand head of cattle and above six thousand men perished. Three small isles alone remain, and they are still farther wasting. (Lyell.) It may often be remarked that substances thrown into the sea are not carried down at once to its depths, but rejected many times to the shore, in the direction of the tidal currents. This happens especially with all light, small, and easily moved bodies ; but the case is different with the large blocks of stone, which, continually pressing by their weight downwards, are for the most part gradually withdrawn from the base of the cliff sunk in the beach, and rolled down to the deep. In this manner, when the circumstances admit of it, the whole 490 MODEBN CAUSES IN ACTION. coast is in motion, every high cliff wastes away, the low grounds stretch out, the beach widens and again contracts, shifts upwards and downwards, and travels along, and thus amidst the extremes of constant fluctuation and change, new deposits are continually added to the quiet depths of the sea, and to the lowest parts of the land. As far out as the fluctuations of the waves can influence the bottom of the sea, the new deposits, where uninfluenced by currents, must become nearly horizontal ; in greater depths it seems reasonable to suppose that the materials will be arranged nearly as in deep lakes ; and under the cliffs, the beach being only at intervals exposed to the rush of ascending and descending waves, must have its surface in- clined at corresponding angles. 347 Gibraltar. We have no accurate data on which to found an opinion concerning the utmost depth to which the influence of the superficial undulations of water may extend. The influence of the tidal and other currents of the sea must extend to a great depth, and tend to equalize into nearly horizontal strata the loose materials collected from the waste of the land. Coral islands, &c. These extensive deposits of sand and clay are, however, not the whole of the productions of the sea. The ocean indeed is but a large lake, and, besides the mechanical effects on its borders, is subject to various chemical changes, and to the unceasing agency of the functions of organic beings. Into that vast repository there flow annually great quantities of soluble matter of various kinds, and it is quite conceivable that by the interchange of their elements some chemical deposits may happen. It is also not unreasonable to COEAL ISLANDS OEIGE* OF. 491 admit that many exhalations rising from the bed of the sea may co-operate in such effects. But there is one ascertained cause incessantly in operation which prohably occasions more extensive and permanent precipitation of carbonate of lime than any other process the growth of zoophyta, shells, and Crustacea. However small may be the quantity of calcareous matter suspended in water, the molluscous and zoophytic animals, which require such matter for their stony supports, are sure to possess themselves of it ; and as corals and shells remain when their tenants dissolve away in the water, the bed of the sea is continually receiving important additions from this source alone. Besides these, the cast shells of Crustacea, the teeth, and sometimes the skeletons of fishes and cetacea, must contribute no mean quota to the growing stock. It is perhaps yet an undetermined question to what depths in the sea light and the vital influence of the atmosphere can sustain the growth of plants and animals. We may, however, safely believe that the extreme gulfs of the sea are as devoid of organic life as the central solitudes of a sandy desert, while the borders of the one, and the shores of the other, teem with innumerable forms of life. It was formerly supposed that those immense reefs of coral which divide the waters of the Pacific Ocean, and rear themselves above the waves into associated islands, arose from the deepest parts of the sea, in perpendicular walls. But many observations by Captain Beechey, Darwin, Stutchbury, and other navigators, upon the crater form which the coral islands generally assume, and the volcanic rocks upon which they are frequently based, have produced a very general impression that these polypean races do not exist except at moderate depths. Captain Beechey found the coral of Ducies Island to be forming at a depth of one hundred and eighty feet ; the reef-making madrepores are seldom found below 100 feet. The quantity of carbonate of lime thus produced by the coral animals, with the addition of shells, &c. enveloped by them in their progress, is really enormous, and might almost justify those geologists who think that our stratified limestones are wholly derived from comminuted shells and zoophytes. A great proportion of all the low islands in the South Pacific Ocean is the work of zoophytes, and new islands are daily in progress, and submarine reefs of so great extent, that Captain King found a continued line of coral reef 700 miles in length, from the north-east coast of Australia towards New Guinea. It was interrupted only by a few intervals not exceeding in the whole 30 miles in length. These reefs consist in great part of compact limestone, and Lyell compares them to the ancient calcareous rocks of the basins of Europe and North America. This comparison, so just as to quantity of material, must not be extended to the structure and arrangement of the several masses. 492 MODEBN CAUSES IN ACTION. The rocks of carboniferous limestone have indeed derived a large part of their materials from the calcareous secretions of polypean and molluscous animals -, but tha materials can have been put into their present stratified form only by the ordinary mechanical action of water upon them. A modern coral reef might, by long movement in water, be ground up into something like a limestone bed ; but the sharpness of the angles of the ornamented fossils of all the old cal- careous strata appears to disclaim such an origin for these rocks. At the same time it is to be observed that the corals and other zoopl^tic reliquiae, which abound in some of our limestones, very seldom appear to be in their ordinary places of growth, but rather seem to have been subject to some slight drifting. The corals may therefore in ancient times have grown in reefs, as at present, and this may perhaps be the reason of their irregular and unequal dis- persion in the rocks a fact particularly remarkable in the coralline oolite. On the whole, the Bermudas afford, as explained by Nelson,* the best general term of comparison between modern coral accumu- lations and ancient coralline limestones. * Geological Proceedings, 1834. 348 Needles, from Scratchells Bay. EFFECT OF IGNEOUS AGENCY. 493 CHAPTER XVI. ROCKS PBODTJCED BY THE AGENCY OF HEAT. Below the numerous deposits from water, we discover rocks formerly fluid through heat crystallizations from igneous fusion. Some of the earlier marine strata are obviously composed of materials derived from still older igneous rocks. Thus granite, after being crystallized, has by subsequent disintegrating processes been separated into its elementary minerals ; these at a later time have been again reaggregated, and consolidated into the rock called millstone grit. So with regard to the oldest of the strata, gneiss and mica schist, we believe some of them to be really derivative strata, and to retain traces of their stratification and of their aggregation from separate mineral ingredients, however nearly, by metamorphic agglutination, they may claim to rank among rocks of fusion. Earlier than all the terraqueous condition of the globe, we infer an igneous condition, and behold a spheroidal fluid mass, whose external figure and interior density were in equilibrio with the rotatory and attractive forces impressed on the mass by its Creator and Director. On this basis we proceed to trace in a few pages those operations of the earth's internal heat, by which some classes of rocks have been upheaved from below ; certain alterations have been effected in others ; the earth's crust broken and displaced ; the level of land and sea altered ; the physical condition of the globe modified. These opera- tions are represented in our days by those volcanic disturbances which shake from time to time the solid framework of the earth ; raise islands and depress mountains ; and pour out, on the surface of the land and the bed of the sea, many streams of melted rock, which are always comparable with the igneous products of earlier date, and sometimes undistinguishable from them. Even as the modern daily operations of water furnish the key to the history of primeval strata, so the occasional violence of volcanos throws open the secret labora- tory of nature, and " Lets in light on Pluto's drear abode." The order followed by nature in the production of the crystallized rocks of fusion, seldom admits of more than local determination. If we regard them as acquiring solidification by cooling in zones more or less parallel to the surface, we should have granitic and basaltic sheets of rock generated leloiv, the first uppermost, the last lowermost ; while above the several strata were produced in a series beginning at the bottom. In this sense the rocks of fusion may be called, with 494 BOCKS PRODUCED BY THE AGENCY OF HEAT. Lyell, hypogene. Certainly under particular areas of country, we find evidence of the liquefaction of one set of igneous products after the solidification of others. Thus dikes of basalt traversing granite show themselves to have been in fusion after the solidification of granite. Granitic Rocks. Various Conditions of the Production of Igneous Rocks. The circumstances under which the germs of igneous energy may be ex- cited to activity, are so various, that even amongst volcanic products poured into the atmosphere, there is great local diversity. If we remember that, for the most part, the phenomena of submarine vol- canic action are wholly concealed from our view, we shall be prepared 349 Granite Peaks, from Lagan Hill (Arran). to expect that among the masses formerly produced by it beneath the bed of the sea, and uplifted by subsequent convulsions to the day, many varieties of rocks should be met with, differing very greatly from the products of actual volcanos. As the far greater portion of volcanic effects takes place in the deep parts of the earth, where the rocks remain to be again and again exposed to new influences, it is reasonable to suppose that the products collected from volcanic vents form but a small part of the series. The subterranean lavas, now in course of production and consoli- dation, could they be uplifted to the day, would be found very dif- ferent from the superficial lavas, and far more extensive and abun- FOBMATION OF BOCKS BY IGNEOUS AGENCY. 495 dant. Though, as the preceding section has shown, there be many close analogies between ancient and modern igneous rocks, we ought to expect that the most abundant of these old rocks, while they afford sufficient evidence of their being generated by heat, should appear different from ordinary lava. Granitic rocks are exactly in this case ; they are more abundant than the trap rocks, which most closely imitate volcanic products, and have a different general cha- racter. Yet as between superficial and subterranean lava every variety of products may be expected to occur, corresponding to the various conditions, we find between granitic and basaltic rocks so many intermediate varieties, that it is impossible to separate, by hard and decisive characters, even these extremes of the series of old igneous rocks. Basalt is really a volcanic product, in the restricted sense of the word, though not exclusively so ; and thus we have from vesicular pumice and glassy obsidian an uninterrupted series of gra- dually changing aggregations to granite. Granite is a most variable rock. Even in limited districts it exhi- bits itself at detached points, with very different mineral aspect and accompanying phenomena. In Cumbrian districts, for example, the granite north-east of Keswick is composed of white felspar, gray quartz, and black mica ; that of Shap Fells has reddish or yellowish felspar, and is largely porphyritic ; that of Muncaster Fell, near Eavenglass, is often a binary compound of gray quartz and white felspar, and other varieties abound round Devock Lake. Rocks allied to Granite. Granite deviates on the one hand by continual decrease of the magnitude of its particles into very close grained felspathic rocks, which are greatly analogous to certain kinds of porphyry ; on the other, by the substitution of hornblende for mica into syenite. As examples of the latter change, we may in- stance the syenitic granites of Cruachan and Strontian. The former is illustrated in the granite veins of Arran, and in the fine grained granite of Wastdale and Dufton Pike, in Westmoreland. In some cases it might, perhaps, be safely admitted, that the same originally fluid mass has been consolidated partly into granite and partly into porphyry, according to the circumstances in which the lapidification happened. In the Valteline granite deviates into hypersthene rock. General Argument. It would be a mere waste of time to repeat, for the particular case of granite, those arguments, derived from the crystalline aggregation of many minerals never known to be pro- duced from water, but several of which have been fabricated in the furnace, and nearly all are volcanic products, which estabh'sh the probability of the igneous origin of the whole class of plutonic rocks. We have shown above that the composition of granite passes by very easy steps to that of rocks whose igneous origin is perfectly unques- tionable. If to this we add the fact, of granite entering cracks and 496 ROCKS FEODUCED BY THE AGENCY OF HEAT. fissures in contiguous rocks, as clay slate in Cornwall, hornblende slate in Glen Tilt, gneiss in Cumberland and at Stroritian, we shall have said enough in the present advanced state of geology to secure the admission that granite was generated by heat. The alternations which in several countries obtain between granite and some of the older stratified rocks, as mica schist, gneiss, &c., seem not at all irreconcilable with this view ; but they will hereafter, when rightly understood, be found of great value in determining some peculiar conditions of the granitic eruptions. Peculiar Character of Oranite. If we seek to understand the cir- cumstances which have impressed upon granite characters so gene- rally distinct from those of the other plutonic rocks, we shall find the following facts important : 1. Granitic rocks usually occur in very large masses below the whole, or a very large part of the whole series of strata, and were evidently formed under the pressure of a great body of water, if not under a pile of superincumbent strata. 2. They are so extensively spread beneath the neptunian rocks as to deserve, perhaps more than any other, the title of an universal for- mation. 3. Granite veins, in proportion to their minuteness and distance from the parent mass, grow continually finer in the grain and more porphyroidal in every respect. This effect is most com- pletely seen along the sides of the veins. 4. In countries where the great masses of igneous rocks are granitic, as for example Cumber- land, the dikes and smaller masses are mostly of porphyry, or of a felspathic quartzose rock, of rather dubious character, which may be called syenite, porphyry, or unmicaceous granite, according to the locality. Such rocks occur about Wastdale head, in St. John's Vale, under Helvellyn, and in High Pike. On comparing these general facts with Mr. G. Watt's experiments on the aggregation of fused basalt, there appears sufficient ground for believing that the very high crystalline character of granite is owing to its being produced at great depths where it was very slowly cooled to the point of crystallization. We may further venture the hypothesis, that much of the rock we call porphyry is merely another state of consolidation of a similar felspathic compound, as trachyte has been supposed to be derived from older porphyries, or even from granite. Comparison of Ancient and Modern Pyrogenons Rocks. It appears, therefore, that among the older pyrogenous rocks we may distinguish the same two leading groups as among the modern volcanic products, characterized by the prevalence of some kind of felspar in the first, and of augite, hornblende, hypersthene, diallage, or some other analogous generally ferruginous or magnesian mineral in the second; that in each of these occurs a great variety in the size, distinctness, and aggregation of the crystals, corresponding to the circumstances FORMATION OF FELSPATHIC BOCKS. 497 of the consolidation and differences of composition of the mass. The following short synopsis will express some of these relations among the older rocks. Plutonic rocks are : 1. Felspathic: as granite, porphyritic granite, porphyry, amygdaloidal porphyry, claystone, pitchstone. 2. Hornblendo-felspathic, Hyperstheno-felspathic, &c.: as syenite, hypersthene rock, gabbro, serpentine. 3. Hornblendic, hypersthenic, &c. : as greenstone, basalt, trap porphyry, melaphyre, amygdaloidal trap, wacke. On reviewing this series, and considering the manner of occurrence of the several members of it, we shall find that the large prismatic structure is perhaps more generally developed in the augitic and hornhlendic pyrogenous rocks, than in the felspathic branch, and that in both groups the highly crystallized varieties, as granite, syenite, and greenstone, exhibit less of this remarkable structure than is common to granular claystone and glassy pitchstone, or fine grained basalt and trap porphyry. Granite Veins. Another thing worthy of notice, is the circum- stance that veins proceeding from the mass of a pyrogenous rock into the small cracks and short fissures of a stratified rock are almost peculiar to granite. This phenomenon is hardly ever noticed along the sides of a dike or interposed bed of basalt or porphyry, and is at least very uncommon in connection with even large masses of green- stone. On the contrary, granite is very seldom found in dikes like the augitic and hornblendic rocks, though there is reason to believe that it assumes the form of overlying masses, and alternates in seeming beds with gneiss or mica slate. (S.E. of Ireland.) This circumstance leads us to suppose that in many of the cases the injection of granite happened not near the surface, or at a time of violent eruption and elevation of strata, but at great distances below the surface, while the strata were sunk into zones of depth so great as to come under the influence of the earth's interior temperature. The variety of interesting considerations connected with granite will justify us in taking a more extended review of its mineral and chemical composition than will be necessary while treating of other pyrogenous rocks. Granitic rocks have long been regarded as the source of most of the ingredients of sedimentary strata ; a newer theory supposes that granitic rocks are continually forming beneath our feet, in quantities proportioned to the time, by the action of subterranean heat upon the ordinary strata. On both of these points some further information concerning the composition of granite will be useful. Felspar. Granite is essentially a felspathic rock. Whatever varia- tions happen in respect of the quantity of other ingredients, felspar, 2 K 498 BOOKS PKODUCED BY THE AGENCY OF HEAT. in a crystallized state, is universally the basis of granite. In graphic granite the planes of crystallization of the felspar are continuous for great spaces ; in porphyritic granite it sometimes happens that the axes of the prismatic crystals of felspar lie nearly in the same direc- tion ; but in common granites it is probable that the crystals of felspar lie in all directions, like the calcareous crystals of primary limestone. The felspar is red, white, green, &c. Felspar is now the title of a family of minerals, and includes several species and varieties. Those most frequent in granites have a large proportion of silica compared to the alumina which they contain. They are, in fact, mostly trisilicates of alumina, with additions of silicate of potash, silicate of soda, or silicates of bases, isomorphous with these respectively.* Orthoclase, or potash felspar. Adularia, and common felspar, have a low specific gravity (2-5 to 2'6); melt to a porous glass; contain essentially 65-4 silica, 18 alumina, 16-6 potash, and other bases. Symbol Al Si 3 -f- KSi. Albite, less frequent in granite, has a higher specific gravity (2-59 to 2-65), melts more easily; contains essentially 69'3 silica, 19'1 alumina, and 11-6 soda, and other bases. Symbol Al Si 3 ~f- Na Si differing from orthoclase hi the second term only by the substitution of Na (soda) for K (potash). Oligoclase occurs in some granites, with a specific gravity of 2'6 to 2-7; melts easily; and contains essentially 63 silica, 23 alumina, and 14 soda, and other bases. Symbol Al S 2 ' + Na Si. Quartz. Quartz, in a gray, transparent state, more or less evidently crystallized, is almost never absent from granite, but its quantity is very unequal. In graphic granite, quartz, in a sort of interrupted crystallization, is engaged among the laminae of felspar, so as to assume angular and intersecting figures not unlike the characters of some Oriental language. In the porphyritic granite of Westmoreland the natural faces of the large crystals of felspar are impressed with very small bipyramidal crystals of quartz ; and in other granites the quartz may generally, with care, be found crystallized in this form, so as to present on a polished face a regular or elongated hexagonal section. There seems also in some granites a portion of uncrystallized quartz, which is entangled among the other ingredients in irregular shapes. Binary granite, of quartz and felspar only, is seldom met with in Great Britain. It forms part of Muncaster Fell in Cumberland. Mica. Mica, the third ordinary ingredient in granite, is occasion- ally very abundant in it ; but sometimes absent. It is universally * See Daubeny on Volcanoes, 2d edition, p. 13. EOBMATION OE EELSPATHIC KOCKS. 499 crystallized, generally in regular hexahedral plain laminae, which enter or cut into the crystals of felspar and quartz, without being themselves interfered with. The direction of the crystals of mica is indeterminate; they do not occur in continuous laminae, so as to cause the rock to cleave; for though porphyritic granite is in a certain sense cleavable, this arises from the parallelism of the crystal- line axes of the felspar. Yet in some Cornish granites we occasion- ally see the mica aggregated together in a sort of shell, which gives a notion of some kind of lamination, arising perhaps from a limited intestine movement of the mass. There are several species and varieties of the family mica. The most common in granite, potasn mica, with specific gravity 2' 8 to 3*0, is fusible ; contains about 44 to 45 silica, 36 alumina, and per- oxide of iron, 10 to 14 potash, and other bases, combined with silica, and about 6 water. Order of Crystallization. It is generally presumed that the three most common ingredients of granite were crystallized together ; by which is meant, that the consolidation of all the crystals was con- temporaneous, neither preceding nor following another. This seems not always exactly true. In the Portsoy granite, the quartz is impressed by the felspar ; in other granites the impressions of the substances are observed in a different order, and the quartz gives its form to the felspar. This, however, is the least common. Spiculae of schorl often shoot across both quartz and felspar.* In many cases we cannot doubt that mica was crystallized before the other ingre- dients. If we follow the indications of the penetration of crystalline forms, we shall find in several instances that the figure of the quartz was complete before the felspar was wholly consolidated ; and perhaps, adding to this the consideration that the detached crystals of felspar in the solid parts of granite have, in general, only one, and that the primary form of the crystals, or the primary but slightly modified, while quartz and mica invariably appear in secondary forms, we may venture to conclude that such detached felspar in porphyritic granite, was the last crystallized, and, by consequence, has imparted to the mass its most important features. In many large grained granites are cavities, in which free crystallizations of the ingredients occur. In these cases the minerals show themselves in much greater variety of forms, especially the quartz and the felspar. The former assumes variously terminated prismatic forms ; the latter is in rhombic prisms variously modified. (Baveno ; Arran.) Contemporaneous Veins. The aspect of granite is often diversi- fied by the occurrence of what are called contemporaneous veins ; a term which is meant to convey the assertion that the difference of * Playfair, 111. of Huttonian Theory, p. 320. 500 BOOKS PRODUCED BY THE AGENCY OF HEAT. character which it marks was coeval with the formation of the rock. In the large grained granite of Arran and Cornwall, the contempo- raneous veins usually appear as long, narrow, ramifying portions of finer grain and a different proportion of ingredients ; sometimes with more mica, sometimes with less. The boundaries of these "veins" are indistinct, and the two structures gradually pass into one another. It will be readily conceived, that a stone composed of crystals so much independent of each other may, especially when the felspar is not very predominant, be very far from solid ; it may be very full of minute fissures. These are often clearly enough perceived, some- times partially filled with small grains of quartz, steatite, felspar, mica, &c. When the stone is by any means subjected to decom- position, the several crystallized ingredients easily separate along these opening cracks. Embedded minerals. It is almost unnecessary to enumerate the various other minerals which are disseminated in granite, except for the purpose of showing how many minerals may be developed from the same fundamental fluid mass. As all of them are definite com- pounds of certain ingredients, and only one simple earthy substance (quartz) remains as a residuum, it is no wonder they are mostly silicates of earthy substances, and that their relative quantity is very unequal, depending upon the possible atomic combinations which should exactly exhaust all the ingredients except the superfluous quartz. Silicates. Tourmaline, topaz, zircon, cordierite, epidote, garnet, lepidolite, petalite, triphane, steatite, talc, schorl, hypersthene, hornblende, augite, beryl, chryso- beryl, pinite. Sulphuret of bismuth, sulphuret of molybdenum, tungstate of iron, rutile, oxide of tin, graphite, oxide of iron, &c. The tourmaline, which is frequently found diffused in crystals, single or grouped through the granite of Dartmoor, is sometimes accumulated in so great a proportion as to exclude the other parts. Hence we not unfrequently find insulated patches of nearly a black colour, and a close grained texture in the midst of a granite, princi- pally composed of large and distinct white crystals and felspar.* Restricting ourselves to the more common varieties of granite, we may observe, that the difference in the crystallization of the ingre- dients could not be determined a priori, from considerations of the relative fusibility of the minerals ; because, in fact, these minerals were all developed from, one uniform melted mass, in which the only distinct parts were the elementary substances of silica, alumina, lime, potash, oxide of iron, &c. ; and it would depend chiefly upon the rela- tive cohesive forces and chemical attractions of certain proportions of * Kidd, Geology, p. 18. COMPOSITION OE GEAJTCTE. 501 these ingredients what crystals should be first generated. In ternary granite, for example, it may not be that mica and quartz were crystallized before felspar, because this latter is the more fusible substance, but because out of the mingled mass of elementary sub- stances the particular combination which constitutes mica was endowed with the highest attractive energy. Mica might be formed out of a melted mass at a temperature very far below that required for its own fusion ; this being separated, there would remain a silicated felspar, from which the excess of silica being separated, it might depend upon the state of the mass as to heat, or some other condi- tion, whether both quartz and felspar should crystallize together with mutual penetration, or one impress the other. Elementary Composition of Granite. If we assume granite to COn- sist of 20 parts of potash felspar, 5 parts of quartz, 2 of potash mica, the fused glass from which, on cooling, these minerals were crystal- lized, must have contained about Silica 1853"| f 1353 "| Alumina 404 ! | 404 { Potash 282', f v , I 282 I formed felspar and mica, leaving Lime 40 f a ] 40 f a residuum of 500 silica. Ox. iron 44 j 44 | Ox. mang. ... 3J L 3 J Had the proportions of alumina and the metallic oxides been greater, it is probable that more mica would have been formed ; had they been less, less mica and more felspar might have resulted ; and the proportions of the ingredients might have been such that the mica and felspar might be provided with their constituent potash and other parts, hornblende or augite, or hypersthene, with their lime, magnesia, &c., and a residue of quartz remain. According to the rate of cooling, we might have a large grained or fine grained granite, or a nearly compact rock. If the quantity of felspar was very great, and the cooling rightly proportioned, the mica and quartz might be crystallized in a compact, earthy, or glassy uncrystallized basis. Thus felspar porphyry would be produced from the same ingredients as ordinary granite ; and the whole investiga- tion appears to teach us that the mineral characters of pyrogenous rocks depend as much upon the circumstances of their solidification as upon original differences of chemical composition. With this all observations on these rocks fully agree ; and it is, therefore, in a right spirit of philosophical generalization that geologists have now accustomed themselves to view the whole series of plutonic and vol- canic products as the varied results of one original mode of calorific action operating under a variety of conditions as to cooling, pressure, limitation of space, and other influential circumstances. 502 BOCKS PEODUCED BY THE AGENCY OF HEAT. Relative Age and characteristic Phenomena of Pyrogenous Rocks. Age of Plutonic Rocks. Were, however, our inquiries concerning the relative age of plutonic rocks to be answered only by appeal to observation of the phenomena which they present in contact with one another, the research must be abandoned. For they neither show themselves so often in connection, nor display, when in connection, such constant marks of relative antiquity as to permit us to recognize more than one general truth, viz. that granite is very often the oldest and basalt very often the youngest of these rocks. But by studying separately the age of each of these rocks in relation to the strata which adjoin it, we obtain a more extensive and more exact series of determinations concerning the periods when they have been erupted through the consolidated crust of the earth. The impor- tance of these determinations in inductive geology is so great as to demand a preliminary statement of the mode of reasoning employed in obtaining them. 1. When in any country a certain class of rocks, as for instance the slate rocks, have been convulsed and thrown into new positions before the deposition of another set upon them, as for instance the carboniferous rocks, and we find occupying the axis or nucleus of the dislocation a mass of granite, it is certain that such granite is older than the carboniferous system, because it was uplifted with the older slates. If, in addition, this granite sends veins through the slate rocks so as to prove that it was uplifted in a melted state, we must infer that it is (considered as a solid) of more recent origin than those slates ; and, in fact, that the antiquity of its latest fusion is exactly measured by the date of the convulsion. If there be no veins thrown off from the mass of granite, and no other satisfactory proof of its having been uplifted in a melted state, the age of the igneous rock is indefinable, except by saying that it is older than a given stratified rock. Such a case occurs in the Ord of Caithness. It appears, then, that in any case of convulsion the era of the elevation of the igneous rock is determined by the convulsion, but whether it was actually generated at that time from a melted state, requires other evidence. Now this consolidation from a melted state is what fixes the age of an igneous rock. Granite may, perhaps, have remained melted in the deep parts of the earth through many geological periods, but its age as a rock is counted from the period when its fusion ceased. 2. In Derbyshire the carboniferous limestone is interlaminated for great lengths by an igneous rock (toadstone), which has evidently been poured out at certain intervals by an ancient submarine volcano while the limestone was in formation. The age of such a rock is fixed by the age of the limestone. ARRAtf GENERAL FEATURES OF. 503 3. The basalt of dikes which pass through certain strata, is, of course, not more ancient than the newest strata divided ; if at any point the dike should be covered by newer strata which are undis- turbed by the dislocation accompanying it, we may generally admit that the basalt is older than these strata. Such a case, perhaps, occurs in those dikes of the Durham coal field, which do not pene- trate the magnesian limestone ; but it is not always to be affirmed, because the dikes are there often unaccompanied by dislocation. These instances are sufficient to show the truth of two propositions of general application to this subject. When igneous rocks accompany convulsions, we can always fix the minimum of their geological antiquity ; when they throw off veins or intrude in the shape of dikes, or interpolated beds, among strati- fied rocks, we are able to assign the maximum of their antiquity. Guided by these views, and restricting our illustrations as much as possible to the British Isles, we may proceed to describe some of the characteristic phenomena occasioned by the appearance of plutonic rocks, and to fix the eras of their production. First, we shall notice some of the general features of a district remarkable for the number of these rocks brought into a small com- pass and presenting diversified effects, and then select instances proper to make known the characters of each. We shall take an example of the phenomena of pyrogenous rocks in general from that gem of Huttonian geology the justly celebrated Island of Arran, an examination of which may be safely pronounced almost indispensable to a complete geological education. Arran. General Feature*. The Island of Arran has been very often described, and by eminent geologists. Jameson, MacCulloch, Necker, Murchison, and Sedgwick, Oeynhausen and Von Dechen,* have all written ably on the inexhaustible subject of this little world of geological phenomena ; and were it not for a reluctance to add to this weighty literature, other voyagers would be unable to restrain themselves from describing some neglected but curious phenomena. The leading features of Arran are its mountainous and truly Alpine scenery in the northern extremity, and the elevated plateaux of its southern portion. These latter are generally composed of trap rocks, partly syenite, partly porphyry, partly greenstone, with many dikes of greenstone and pitchstone passing through the red sandstone strata * The short account here given is entirely from the author's personal observations, in 1826. Since the essay was printed, Mr. Ramsay has minutely surveyed the island, and we have bor- rowed some of the drawings with which, as well as by a beautiful model, he illustrated the struc- ture of this charming island. 504 EOCKS PKODTJCED BY THE AGENCY OF HEAT. which appear around the coasts. The highest northern eminences are granitic mountains forming the nucleus of a great conical elevation of slate rocks, which, overlaid by the red sandstone formation, form a narrow but unequal zone round the granite. The small size of the island, combined with the elevation of the mountains (nearly 3,000 feet), gives to the short glens a very sudden depth, and permits the cliffs to show the great curvatures of strata. Dikes and overlying masses of greenstone, felspathic and trap porphyry, various sorts of claystone and pitchstone, are seen abundantly both on the eastern, western, and southern coasts ; and so perfectly are all the phenomena exhibited, that it is difficult to imagine any space of the same limited extent more worthy of being studied for the purpose of understanding the mutual relations of pyrogenous rocks. 350 From the top of Goat Fell (Arran). That the granite of this island was subject to pressure, while in a melted state, seems sufficiently demonstrated by the fact of its throwing veins through the surrounding slate rocks ; this pheno- menon may be very well studied at Tornidneon. That the fluid granite speedily acquired solidity in these veins, is a fact which seems to imply upheaval to situations where quick cooling was practicable. That its main elevation was subsequent to the deposition of the whole red sandstone system seems also proved by the curvatures which these strata have undergone. This would give for the main AEEAN GEKEEAL FEATUEES OF. 505 elevation of the granite of Arran a period considerably later than that usually assigned to the principal part of the Highland mountains. The granite is, as far as can be known, the oldest pyrogenous rock to be seen in the island, for it is traversed by dikes of greenstone and pitchstone, like those which cross the red sandstones. It is observ- able, however, that these dikes are most numerous at some distance from the granitic centre. At Corygills, at Lamlash, and Tormore, they are exceedingly abundant in the red sandstone, while in the north-eastern face of the island, where that rock is nearer to the granite, fewer dikes appear, and about Loch Kanza the slate is still less divided by them. Perhaps we may venture to add another generalization ; viz. that these dikes are most abundant beyond the 351 Drumadoon (Arran). line of violent flexure of the strata from their horizontal position. After measuring with care the directions and breadths, and noting the characters of forty-four dikes, chiefly of greenstone, between Brodick and Lamlash, and also those at Tormore, it did not appear to the writer of this notice that any other dependence of the direction of those dikes upon the local centre of the granitic eruption could be traced. While in the eastern side of the island, about Corygills, the dikes in the red sandstone are chiefly greenstone and basalt, with a sparing admixture of felspathic and porphyritic claystone and pitchstone, those of Tormore, in light coloured sandstone, are chiefly pitchstone, claystone, and trap porphyry. On both sides occur interposed beds 506 BOOKS PEODUCED ET THE AGENCY OF HEAT. of pitchstone, divided into columns ; on the east are overlying green- stones in rude colonnades ; on the west trap porphyry columns ; on the east the claystone dikes are highly prismatic ; on the west occur many interposed beds, and an arched vein of claystone. The pitch- stone of the eastern side is black or green, that of the western coast often variously coloured and graduating to something like hornstone, or to claystone. It is, in one point, at Tormore, of that concre- tionary structure which reminds us of some kinds of obsidian and sphaerulitic traps. Alterations of Stratified Rocks. The effects of the pyrogenous rocks upon those in contact with them are less striking in Arran than in many other situations. No new minerals are produced in the slate 352 Granitic ridges, Glen Sannox (Arran). where the granite touches it, nor in the red sandstones where they are hardened by the greenstone dikes. This hardening is very various in degree, and the causes of these differences are not very evident even upon the examination of many cases. The hardening effect is sometimes communicated to the distance of two or three feet into the neighbouring rock, but generally not to more than a few inches. The hardened parts sometimes stand up in narrow crests. Where dikes cross, it has been found that one of the planes of intersection of the greenstone dikes has been marked by the occurrence of a very narrow band of black pitchstone. The base of the pitchstone pillars PYEOGENOTTS BOOKS. 507 of the interposed bed in Corygills is softened, where it touches the sandstone below, to a kind of kaolin. It is impossible to say what was the geological epoch of the later pyrogenous eruptions of Arran, further than that they were posterior to the whole red sandstone system there. If this be correctly taken by Murchison and Sedgwick to represent both the old and new red sandstone systems, they are later than most of those known in Eng- land, and, for aught we can tell, they may be as modern as the basaltic eruptions of the north of Ireland. Geographical Relation of Pyrogenous Rocks. It is remarkable that, amidst all the profusion of greenstones, pitchstone, claystone, and porphyritic dikes, which appear a little remote from the granite, no granite dike is seen ; while in the granite, whose elevation seems to be the local centre of all those exhibitions, no hornblende or augite occurs. That granite and the trap dikes are of different antiquity has been shown before ; but it seems also to be implied either, first, that at successive epochs different rocks lay melted under the same localities ; second, that the local production of pyrogenous rocks is somehow governed by relations of level or distance, or subject to an obscure reciprocity of position. It seems worth while to follow out this idea. Along the Pennine chain, the axis of dislocation shows, at points, granitic and greenstone rocks, but very few mineral veins are wrought. The slopes a little removed from this mountain edge contain many valuable lead mines. The mining district of Shrop- shire, described by Murchison, appears related to the greenstone ridge of Corndon nearly in the same way ; for though along this axis no mines occur, they abound in a line at a small distance parallel to it. Perhaps to these analogies we may add the instance of the diver- sified porphyritic masses which run irregularly parallel to, but re- moved from the granitic axis of Cumbria. Finally, to rise to a greater generalization, Von Buch's views of the relations of the granitic axis of the Alps and the augitic porphyries (melaphyre) along their southern flanks appear to be decidedly analogous, and there seems at least thus much to be inferred from the points of agreement among these several examples of the relative position of ignigenous rocks, that the elevation of an axis or nucleus of granitic rocks was attended or followed by very numerous fissures at a small distance removed, which, after some geological interval, were filled by rocks of a quite different nature from those which were erupted at the time of the first disturbance. A case of this kind occurs in the Malvern hills, where the fusion of the syenite ceased before the earliest recognizable convulsions, and greenstones afc a later time passed, melted, through it and several superposed strata. Antiquity of Granite. It might be doubtful whether any granite visible in the British islands could claim greater antiquity than the 508 BOOKS PBODTJCED BY THE AGENCY OF HEAT. silurian rocks, except for the cases of alternating granite and mica slate, quoted from Weaver. The granite of the Cornish chain in some places throws veins into the adjacent clay slates, and generally appears to change very greatly the nature of those rocks, so that we are compelled to rank it as a more modern product. The granites of Cumberland and Westmoreland, and those of the Gram- pians, if their age be judged of from that of the convulsions accom- panying them, and from the veins which they throw off, must be pronounced to be of nearly the same antiquity. In the Island of Arran, the granite may not be so old as even the red sandstone which overlies the carboniferous limestone; in the Alps it must perhaps be supposed to have been in fusion even since the tertiary epoch. Granite Veins. A few years ago granite veins were considered as rare eruptions, but at present it is difficult to find a satisfactory ex- ample of any extensive tract of granite, without the occurrence of such ramifications through the neighbouring rocks. They occur in Cornwall, Cumberland, and Arran, in Ben Cruachan, at Strontian, in Glen Tilt, and generally throughout the Highlands. The same is true for the continent of Europe ; and perhaps we may nowhere find a better example of the elevation of granite in a solid form, than that described by Murchison at the Ord of Caithness. This granite, on its northern flank, supports the old red conglomerate, whilst to the south it occupies a cliff on and near the shore, the verge of which affords a remarkable breccia, compounded from all the beds of the oolitic series that occur on this coast. This breccia of sandstone, shale, and limestone, is tilted off from the granite wherever that rock protrudes upon the shore, whilst the strata are regularly de- veloped where the granite re- cedes into the interior. No veins or portions of the granite are to be met with in or above the oolitic breccia, which, by its dis- turbed position, appears to fix the maximum of antiquity of the elevation of the granite not be- yond the age of the coralline oolite. Tornidneon. The granite veins of Tornidneon in Arran pass from a body of very coarse grained gra- nite through nearly vertical lam- inae of dark quartzose clay slate ; the line of junction dividing the One of the veins encloses fragments 353 whole side of a hill (fig. 353). GKAtflTE VEINS FORMATION OF. 509 of slate, and divides itself into branches which cross the laminae of slate, cutting off both the quartzose and argillaceous laminae. The granite becomes much finer grained along the veins, and nearly in proportion to their smalmess ; so that in the narrowest veins it is nearly compact. Strings of fine grained granite divide the coarser sort. Glen Tilt. In Glen Tilt, MacCulloch has described nu- merous and valuable facts of this nature. At the bridge be- yond Forest Lodge, granite, hornblende slate, and primary limestone are very 'curiously associated. Veins of red granite here divide the other rocks, and enclose fragments of them. The singular interlacements of the rocks here will be understood by the sketch taken on the spot in 1826. 1. Primary limestone laminated by hornblende and red felspar in curved lines or detached masses, round which the laminae of limestone bend, crossed by granite and red felspar veins. 2. White quartz rock and red felspar crystallized. 3. Felspathic rock, red, with layers of black hornblende. 4. Limestone laminated with felspar. 5. The same with less felspar. 6. Hornblende and felspar in layers. 7. Laminated limestone. (a.) Red felspar vein a little quartz. 8. 9. Hornblende, with layers, masses, and veins of white quartz, and red felspar, which substances often occur together, making binary granite of very large grain. 10. Limestone, with red granite veins. 11. Limestone, red granite veins, and white calcareous spar veins, which divide the granite veins. 12. Red granite, composed of red compact or crystallized felspar, white quartz, and black or gray mica, and encloses hornblende masses which are divided by veins of granite ramifying from the general masses of that rock. Cornwall. The extremity of Cornwall has long been famous for the great variety of curious phenomena connected with the granite veins which there divide the argillaceous slate, hornblende slate, and greenstone rocks, all included by the miners under the title of killas. So many writers of eminence, both English and foreign, have described and reasoned upon these occurrences, that it is difficult to select from the immense variety. The following is Majendie's 510 BOCKS PRODUCED BY THE AGENCY OP HEAT. account of the veins at Mousehole, three miles south-west of Penzance : " At this period the clay slate ceases, and the granite commences, forming a promontory which runs out in a southern direction from the central ridge. The slate is of a gray colour ; it is in strata nearly horizontal, but having a slight dip to the east ; it increases in hard- ness near the junction. The granite, which is generally coarse and porphyritic from the large embedded crystals of felspar, becomes here of a finer grain, with black mica and light flesh-red felspar. On the north it laps over the schistus. At this spot numerous granite veins, varying in width from about a foot to less than an inch, pass through the slate ; the two principal veins proceed nearly east from the hill above, for more than fifty yards, until they are lost in the sea. One of these, not far from its first appearance, is divided and heaved several feet by a cross vein consisting of quartz intermingled with slate ; fragments of slate appear also in the granite veins. The most remarkable vein, after proceeding vertically for some distance, sud- denly forms an angle, and continues in a direction nearly horizontal, having slate above and below." * The killas at this place has much the aspect of greenstone, and it appears generally true that the clay slate is much altered in character round all the granites of Cornwall and Devon. (See De la Beche's Geological Map, Devon.) The veins of granite are generally most fine grained towards the walls. Von Oeynhausen and Von Dechen mention three principal veins at Mousehole, one 3J to 10 feet wide ; quartz veins cross the direction of the granite veins, and sometimes divide them, and apparently alter their character. Schorl occurs ir- regularly in the granite, and in some of the quartz veins. In other localities, veins of this mineral present interesting phenomena. The intricate character of the venigenous masses of Mousehole will be best understood by consulting the diagram, copied from the sketch (fig. 355) of the distinguished Prussian geologist above named. At Cape Cornwall, a granite vein heaves a quartz vein in a direc- tion contrary to the general law, stated in page 34. In the Lizard district granite veins divide serpentine. 355 * Cornwall Geol. Soc. Trans., vol. i. FELSPA.E POEPHTET. 511 Felspar Porphyry. Ben Nevis. The abundance and variety of felspar porphyry, in great masses on the summit of Ben Nevis, and in the awful valley of Grlen Coe, is familiar to every traveller in the Highlands. The porphyry of Ben Nevis has been shown by Von Oeynhausen and Von Dechen to have been erupted through the granitic basis of that mountain. The diversified porphyries along the vertical precipices of Glen Coe send veins through the subjacent granites, in number proportioned to the proximity of the situation to the great mass of porphyry. This rock is not columnar (MacCulloch) . It varies through every stage, from claystone to felspar porphyry, the different varieties being sometimes gradually and sometimes suddenly con- nected. Breccia, composed of fragmented claystones and porphyries (like those on Ben Nevis, and some in Cumberland), are often seen in Grlen Coe. In the mountain of Cruachan, which overlooks Loch Awe, the hornblendic granite and schist rocks are traversed by a great variety of large felspar and trap porphyry dikes, and some changes of ap- pearance happen to the clay and mica slate, very difficult to be described. MacCulloch* describes the porphyry dikes as perpen- dicular, varying from 3 to 50 feet in breadth, traversing alike the schist and the granite veins which divide it, but not in any degree intermingling with either. Dikes of porphyry, of different kinds and colours, may run near or in con- tact with each other ; but in all cases these and other dikes of basalt or trap porphyry are very distinct at the edges, though 356 firmly united to the rock which encloses them. Fig. 356 shows veins of granite traversing the schist of Cruachan, themselves crossed by dikes of two kinds of porphyry.f Cumbrian Mountains. In the Cumbrian mountains felspar por- phyries occur in many situations, and with a great diversity of cha- racter. Some have a basis of translucent gray or green felspar, and included crystals of glassy felspar and quartz ; others are composed of a red, opaque, granular felspar basis, and red felspar and quartz crystals ; the basis of others is compact felspar or hornstone, and some have a dark but not basaltic base, with small white opaque felspar crystals. Most of them, like the amygdaloids and greenstones * GeoL Trans., iv. t R>id, iv., pi. vi 512 BOOKS PKODTTCED BY THE AGENCY OF HEAT. of the same region, occur in overlying masses as well as dikes, but real alternations of them with the slates can hardly be substantiated. They seem to have a geographical dependence on the foci of granitic eruption of a peculiar kind. They are not abundant in or very near to the granite of Wastdale, Skiddaw, or Shapp, but they occur at small distances from each of those masses. The Valley of St. John's shows pale red felspar porphyry overlying slate, well crystallized red porphyry in Armboth Fell, and various kinds of felspathic rocks unde/Helvellyn. Dikes of variable greenish porphyry divide the slates of High Pike, and a solitary red dike ranges east and west of the granite of Shap Fells. No porphyry occurs very far from the granites. In North Wales felspathic porphyries appear so connected by alternate bedding with the slates, as to have been subjected to the same elevations and undulations of dip ; and thus not only prove their high antiquity, but also suggest views as to the frequent re- currence of igneous action at the same points of the ancient bed of the sea during the period of the primary slates. Cornwall. Consistently with our views of the origin of the crys- tallized rocks, we may, perhaps, be right in believing that all the complicated, wholly or partially, crystallized rocks, composed of felspar, quartz, and mica, which are included between and which traverse the real slaty rocks of Cornwall, are either the result of submarine eruptions during the formation of the slate ; of the sub- sequent action of the heated granitic masses upon the killas ; of posterior eruptions of melted rock into fissures caused by convulsion, or of some gradual conversion and transfer of mineral ingredients, such as we know to have occurred. It is hazardous to reason on phenomena so remarkable as those of Cornwall without reference to other districts. Nothing but preju- dice or indolence will permit geologists, acquainted with other dis- tricts, to neglect the singular and curious facts connected with the Devonshire and Cornish chain. We may freely admit that they, in some cases, point to agencies not yet familiar to our philosophy ; that a full examination of the whole series of granites, porphyries, serpentines, and killas, and of the disseminated and venigenous mine- rals in them, will kindle a brilliant light in the most secret labora- tory of nature ; but one thing is wanting, an exact description of all the characteristic facts observable in each particular case, without the adornment of theory or the disarray of new nomenclature. Mr. Henwood's volume includes a large and valuable series of observa- tions on the mineral veins. See also Conybeare, Buckland, and Sedgwick, Geol. Trans. ; the Trans, of Cornish Geol. Soc. ; the work of Dr. Boase. ELEVATION OF STEATA. 513 Syenite. Hornblende, the mineral which in syenite wholly or principally replaces mica, has a composition equally variable, often reducible to such a formula as B Si + B 3 Si 2 where B is generally lime, but some- times protoxide of iron or soda, and B 3 is generally magnesia, but sometimes protoxide of iron. It contains about 41 silica, lime 14, oxide of iron 15, alumina 16, and magnesia 14 ; easily fusible. Maivern. The Malvern hills, long since described with much ability by Horner, and more recently investigated by Murchison,* whose steps were followed by the author of these pages,t will serve to illustrate the phenomena attending syenitic extrusions. The picturesque chain of the Malverns rises at its centre to 1,444 feet above the sea, and looks down over a vast and beautiful region. On the eastern side the descent is abrupt to plains of horizontal new red sandstone, on the western more gradual and diversified by ranges of woody palaeozoic hills whose bearing is parallel to that of the chain. Beyond are the coeval mountains of Wales. Many small narrow valleys descend to the east across the steep slope of the hills. The verdant surface of these hills, and the circumstance that the pyrogenous rocks are very much decomposed and fissured near the surface, prevents very frequent observation. The great mass of the rocks is of a syenitic rather than granitic character, varying, however, much as to the relative proportions of felspar, hornblende, mica, and quartz. We may collect masses of true granite, and binary granite, true syenite and rocks not separable from greenstones, slaty horn- blende rocks, serpentinous rocks, epidotic compounds, compact felspars, and many other segregated varieties. The felspar varies in tint from white to a fine red, and in crystallization from the finest grain to the broadest adularian lamination. Mica lies scattered in broad plates with quartz, or occurs in a massive vein. Chlorite forms a vein. Epidote covers fissured surfaces. There is no known metallic ore of value. Veins of granite are frequent as segregations, and traverse the oldest metamorphic masses, some of which are characteristic gneiss with flexuous laminse. Veins of sulphate of barytes, calcareous spar, and epidote, red haematite, &c., occur in the syenitic rocks. Graphite has recently been discovered, in the rail- way tunnel, by Mr. Burrow. Elevation of strata. The stratified rocks which are dislocated along the line of the Malverns are best seen on the western slopes, the oldest of them are fucoid sandstones, with a somewhat volcanic aspect; oleni and agnosti appear in black shales above: then * Silurian System. 1837. t Memoirs of GeoL Survey, ii. 1. 2 L 514 BOCKS PBODTTCED BY THE AGENCY OF HEAT. follow fossiliferous sandstones, considered to be Caradoc beds by Murchison, but regarded as belonging to a higher group by Sedgwick. Into none of these beds does the syenite throw any veins. They rest upon it unconformedly. One of the upper beds of the series, somewhat below the Woolhope limestone, is of a brecciated character, and contains fragments of the syenite, mixed with abundance of or- ganic remains, chiefly of the earliest Wenloch (upper silurian) age. Thus it is apparent that the fusion of the syenite of Malvern ceased before the accumulation of the lower palaeozoic in that area ; that the igneous rock furnished materials to silurian conglomerates, and was upheaved with them at a much later period, in a solid form. The sandstones, limestones, and shales are partly vertical, or partly overthrown to the west, so that for some distance to the west the series of strata appears inverted, and the really newer rocks come out from under the older.* Much local confusion and disturbance of declinations accompany these general indications of violent upward heaving along the axis of the chain. Horner's very judicious re- flections on the bearing of the phenomena of the Malvern upon the then prevalent discussion of the Wernerian and Huttonian theories of geology, will be perused with great satisfaction and pleasure as anticipating many of the clearest arguments known in the present advanced state of the science. As the unstratified rocks have been thrown up along a line from north to south, the bearing of the ele- vated strata ought, in general, to be parallel to that line, and this has been shown to be the case : the force would be greatest at the point where the unstratified rocks burst forth, and accordingly we find the strata there generally vertical, or even thrown back and in some degree inverted. The eastern boundary of the Malvern is a great fault, throwing down to the east enormously. The same phenomena of inverted strata were observed by Murchi- son parallel to the Abberley hills, which are on the prolongation of the Malverns ; and we are indebted to him for an interesting notice of a dike of dark green syenitic rock, at Brockhill near the Teme, composed of hornblende, felspar, and quartz, eight paces wide, directed west 5 north, and east 5 south. The syenitic rock is prismatic at the sides, the prisms lying across the dike, whose walls are formed of old red sandstone, here of a green tinge, and marls. In contact with the dike and for 20 feet distance the sandstone is hardened, is of a deep purple colour, and has lost its mica ; the marls are altered by the diffusion of carbonate of lime through their mass. I found in these altered strata new vertical structures cleavage on a broad scale replacing the almost obliterated horizontal strata.f This dike is considered as a lateral effect from the great north and south axis of * Homer, Geol. Trans., vol i., confirmed by all subsequent observers, t Memoirs of GeoL Survey, voL ii., part 1. HTPEESTHE10). 515 igneous rocks of the Malvern and Abberley hills. In the south- western part of the Malvern region, we find several felspathic and greenstone masses, and some dikes, dividing the lowest palaeozoic strata, and overspreading in places the black shales with oleni. The shales are usually bleached, and the sandstones partially baked, by this really volcanic eruption, whose date is earlier than the Brockhill dike, but posterior to the solidification of the syenite. The upheaval of the Malvern chain followed the era of the coal formation. The same limits of age must be assigned to the similar rocks of Charn- wood forest, which appear under very analogous circumstances. The partially syenitic rocks of Carrock Fell in Cumberland, may, very probably, be older. The variable rock of Bed Pike and Scale Force is usually called syenite : according to Weiss, the syenite of Wein- bola near Meissen is superimposed on the green sand system. Hypersihene Rock or Hypersthenic Syenite. Hypersthene rock forms the pinnacled mountains of Cuchullm, part of Carrock Fell in Cumberland, certain dikes in Radnorshire, and is not unknown in Cornwall ; it also occurs in Yorkshire in veins passing through the basalt of the carboniferous limestone series in Teesdale. The exhibition of hypersthene rocks in the Valteline has been described by M. Necker. This rock may be very generally described as a syenite, of which the felspar is pale flesh-colour, white, or greenish, and the hornblende is replaced by hypersthene, either in very distinct, large crystals, or small concretionary masses. In the latter case it can hardly be distinguished from common greenstone. Murchison finds consider- able metamorphic action from the hypersthene of Radnorshire obliteration of shells in limestone, and generation of serpentine. In Yorkshire it is contemporaneous with the great basalt formation of the carboniferous epoch ; in the Isle of Skye it is probably more recent than the oolitic era; in the Alps it forms a part of the mineralogical axis, and may have been thrown up even since almost the whole tertiary strata of the basins of Europe. The Valteline. M. Necker, in his account of the Valteline, estab- lishes the fact, that the granitic eminences which rise along the axis of that singular valley of elevation, pass by degrees to common syenite, and afterwards to syenite with hypersthene, in large, small, or even minute crystals, of black or green colour, and metallic reflections. The felspar has a violet tinge. The greater and hypersthenic axis of the valley is coincident with the central line of the great chain of the Alps, from south-west to north-east, and the stratified rocks are vertical on each side, for some distance ; after- wards they take opposite dips to the north-west and south-east. The 516 EOCKS PEODUCED BY THE AGENCY OF HEAT. order of succession may be stated to be gneiss, mica schist, changing to talcose and chloritic schist and clay slate. Veins of fine grained granite pass through the hypersthenic rocks and through the mica schist, sometimes holding fragments of this latter, and quartz veins with black tourmalines divide the granite. Skye. The CuchuUin mountains in Skye, rendered classical by MacCulloch's descriptions, and Forbes's subsequent survey, surround the desolate lake of Coruisk, a grand amphitheatre of steep and barren rocks, which decompose so little as to yield neither sand nor gravel to the torrents. A great variety of appearances is presented by the mixture of the felspar and hypersthene in these rocks, as to crystallization and colour. In some localities the mass is fine grained, and in others graduates to common syenite or greenstone. Von Oeynhausen and Von Dechen state that the hypersthene rocks pass into compact greenstone ; and that the common syenite lies on the hypersthene rock, with an abrupt and distinct junction. One of the most interesting facts connected with this group of rocks is the transmutation of the lias into white granular and compact limestone, where it is in contact with the syenite and trap rocks. This effect happens more constantly at the junction of the Has with syenite than with greenstone or trap ; in the latter case it sometimes happens, sometimes not. The hypersthene rock seldom adjoins the lias ; where it does, like greenstone or trap, it both intersects and covers it. Gabbro, Granitone, Euphotide, Diallage Eock, Serpentine. It is to M. Von Buch that we are indebted for pointing out the importance of the rock, composed of saussurite, or felspar and diallage, called gabbro, or granitone, in Northern Italy. The abundance of serpentine in the Pyrenees, Apennines, and other parts of the south of Europe, has long been remarked. Diallage rocks are equally abundant, often occur in connection with the serpentine, and there is now no doubt as to the fact that these two rocks are very intimately related. Few conclusions of this nature appear better authenticated by observation than the gradation of diallage rock into serpentine, in the Alps, the Apennines, Corsica, and Cornwall. Grabbro has been employed in architecture by the Eomans, and by the family of Medicis at Florence. Stratification of Serpentine. Generally observers agree in repre- senting both gabbro and serpentine as unstratified rocks. When portions of them are included between strata of gneiss, mica schist, &c., they may be viewed as interposed masses. But MacCulloch positively affirms that in Unst the stratification, both of diallage rock and of serpentine, is certainly evident ; and he compares the cases where no stratification can be traced in the latter to analogous GEEENSTOKE. 517 instances in primary limestone. The latter, however, is by far the most abundant case ; and perhaps, taking into account the circum- stance that in Unst the rocks alternate and graduate into micaceous, chloritic, and argillaceous schists, we may reasonably inquire whe- ther the stratified varieties of diallage and serpentine are not recom- posed rocks altered, like some gneiss, by subsequent application of heat. In the northern Apennines Brongniart has remarked the following general order of succession downwards : 1. Serpentine. 2. Diallage rock, in the upper part assuming the aspect of serpentine (at Ro- chetta, north of Borghetto, near Spezia), consisting partly of red crystallized limestone. 3. Jasper rock in thin laminse. Below these are limestones and marly schists, common in the Apennines. In Monte Ramezzo, north-west of Genoa, the serpentine is placed on limestone and talc schist, the limestone is in thin tortuous beds, and is as it were dissolved with the shining slate and steaschist. The direction of the serpentinous masses in the northern Apennines, to which the elevation of that part of the range is ascribed, is east south-east, which is the same as that of the Pyrenees, and of some serpentine rocks about Como. Greenstone. This rock, a mixture of felspar and hornblende, abounds in Scot- land, which has been long and not unjustly considered classic ground for the pyrogenous rocks. We shall take as an example of the occur- rence of greenstone the phenomena in the vicinity of Edinburgh, which have contributed so powerfully to support the philosophical fame of Dr. Hutton. The interesting eminences of Arthur's Seat, Salisbury Crag, the Calton Hill, and Edinburgh Castle, are all com- posed of trap rocks associated with various sandstones and shales of the carboniferous system, and the labours of art have added to the admirable exhibitions of nature. Salisbury Crag. In Salisbury Crag is a very fine section of un- stratified greenstone enclosed between stratified sandstone, conglo- merate, shale, and ironstone nodules, and it is easily seen that both the igneous and sedimentary rocks are altered at their formation. Masses of sandstone and conglomerate, of various forms and magni- tudes, are insulated in a confused manner within the greenstone, and portions of greenstone interposed among the sandstones. No dike appears ; but small veins of calcareous spar, occasionally metalliferous, cross the line of junction. The accompanying drawings and references will sufficiently explain the most interesting phenomena observed, and give a general view of the face of the cliff, as it appeared to the writer in 1826. The letters of reference, o, &, c, mark points 518 BOOKS PKODTJCED BY THE AGENCY OF HEAT. of which, details are given below. On a nearer examination, the point a shows greenstone gradually changing to a red colour and finer grain near its upper surface, on which rest beds of sandstone, ironstone, and shale, as under : 1. The upper part of a greenstone mass, fine grained, and of reddish colour. Veins of calcareous spar, with micaceous iron ore, divide the upper part of this mass, and pass through Nos. 2 and 3 above. 2, 3. Mass of petro-siliceous sandstone, mixed with softer green portions. 4. The same sort of hardened sandstone, with less of the softer parts (here and there a purple tinge). 5. Argillaceous, compact, hard shale of a purplish or green colour, and subconchoidal fracture. 6. Red argillaceous ironstone in green shale. 7. Sandstone beds, reddish and indurated. At the point b (fig. 357) a nearly similar series of alternating stone and shale rests on very similar trap. A portion of sandstone is engaged in the trap, and other signs of violent intrusion occur. At the point c hard red sandstone flags, without ironstone, rest on reddened greenstone. A large quarry at the south end of Salisbury Crag affords an excel- lent section of sandstone beds below the greenstone. Figs. 358 and 359 are taken from this quarry. In fig. 360 the greenstone, reddening below, rests on jasperized sandstone, which is much broken and confused in places. Below BASALT. 519 this is green shale, covering red and white sandstone with conglo- merate. Fig. 361 shows portions of sandstone enclosed in the trap, a \ which grows redder towards the contact with the strata below. The aspect of a portion of sandstone fairly enclosed in trap is seen in fig. 361. Some observations of Lord Greenock on the appearances presented by a section of the compact greenstone and sandstone strata in the Castle Hill, Edinburgh, show the effect of convulsions acting upon both of those rocks since the eruption of the lithoid lava. At some points of this hill the usual transformations of the sandstones, &c., happen in contact with trap ; but in one place beds of sandstone and marl are seen in a state of great disturbance, thrown in angular posi- tions upon tabular greenstone, and not in the slightest degree altered as to hardness or aggregation at the junction. Possibly the expla- nation which applies here, viz., that the junction of the igneous and stratified rock has been occasioned by convulsive movements, which have lifted them both in a solid form, may be found applicable to some other cases in which trap rocks appear to exercise no trans- forming influence on the contiguous rocks. Basalt. This rock is a mixture of some kind of felspar, augite, and oxide of iron, with admixtures of olivine and other minerals. The researches of Dr. Berger, Dr. Buckland, and Mr. Conybeare, on the north-east of Ireland, furnished a highly interesting memoir from the pen of the latter geologist.* The coast between Belfast Lough and Lough Foyle is one boundary of a large tract reaching westward to Lough Neagh, and including the river Bann, which is almost wholly occupied on the surface by basaltic rocks rising at intervals to eminences of 1,320, 1,820, and 1,864 feet above the sea. Under this immense overlying mass of basalt are found several members of the English series of strata not known else- * Geol. Trans., vol. iii 520 BOCKS PBODTTCED BY THE AGENCY OF HEAT. where in Ireland. 1. Chalk, agreeing with the lower beds of the English series. 2. Mulattoe, an Irish name for the green sand of English geologists. 3. Lias limestone (without any other rock of the oolitic system). 4. Beds of red marl, gypsum, and salt, rest- ing on variegated sandstone. 5. At the north-eastern and south- eastern extremity, coal measures, consisting of red sandstones and shales with inferior coal, appear below all the other strata. The mulattoe and lias are often wanting in the section. The superin- cumbent basalt is estimated to have an average thickness of 545 feet, (in Benyavenagh it is 900 feet, in Knochlead 980 feet), and its superficial extent 800 square miles. The phenomena presented by the basalt, exposed along so great a length of coast, are various and remarkable, and we are not only delighted with the magnificent colonnades of Fairhead, and the geometrical pavement of the Causeway, but instructed by the clear exhibition of the effects of dikes dividing both the congenerous basalt above and the calcareous strata beneath. The immense mass of trap rocks in this district exhibits, besides basalt, which is the most abundant material, greenstone, clinkstone, porphyry, wacke, and red ochre. Near the Causeway, the cliffs, according to Dr. Richardson, consist of alternating basalt and red ochre, in the following order downwards : 1. Basalt rudely columnar, 60 feet. 2. Ked ochre or bole, 9 feet. 3. Basalt irregularly prismatic, 60 feet. 4. Columnar basalt, 7 feet. 5. Intermediate between bole and basalt, 8 feet. 6. Coarsely columnar basalt, 10 feet. 7. Columnar basalt, the upper range of pillars at Bengore Head, 54 feet. 8. Irregularly prismatic basalt. In this bed the wacke and wood coal of Port Noffer are situated, 54 feet. 9. Columnar basalt, forming the Causeway by its intersection with the plane of the sea, 44 feet. 10. Bole or red ochre, 22 feet. 11, 12, 13. Tabular basalt, divided by thin seams of bole, 80 feet. 14, 15, 16. Tabular basalt, occasionally containing zeolite, 80 feet. The stratified rocks in contact with the trap have undergone remarkable changes in several localities. At Portrush, the trap (a rudely prismatic greenstone) overlies and perhaps alternates with a flinty slate, which contains numerous impressions of ammonites, belonging to the Has shales. This trans- formation of lias shale, which reminds us of the more extensive phenomena of the same kind in Savoy, was formerly adduced as an argument for the aqueous origin of basalt ! Most of the alterations of stratified rocks on this coast are effected by basaltic dikes, which divide both the overlying masses of trap and the subjacent strata. BASALT. 521 At the foot of the hill called Lurgethan, basaltic dikes traverse the red sandstone conglomerate, which is indurated near the contact so as to resemble compact hornstone. The coal measures, underlying the basalt of Fairhead, are crossed by dikes which have changed the ordinary shale into flinty slate, hardened and pyritized the sandstone for 15 yards, and converted the coal to a cinder. The chalk is affected by many dikes to such a degree as to be converted to a real marble, for 10 feet or more from the side of the basalt. 362 The Giant's Causeway. The order of effects is first a yellowish tinge of colour, then a bluish-gray colour and compact texture, then a fine grained arena- ceous aspect, next a saccharine granulation, and finally close to the dike the chalk is altered to a dark brown crystalline limestone, with flaky crystals as large as those in primary limestone. The flints in the altered chalk assume a gray -yellowish colour ; the altered chalk is highly phosphorescent when heated. Examples occur near Belfast, at Grlenarm, in Bathlin, and other places. Near the top of the stratum of chalk which crowns the cliffs of Murloch Bay, is an interposed bed of wacke 5 or 6 feet thick. For proofs of local vio- lence accompanying the exhibition of the basalt, and many interesting details, the original Memoirs may be consulted. The basaltic formation of Upper Teesdale in Yorkshire has been described by Professor Sedgwick, and its continuation through Nor- thumberland by Mr. Hutton ; and we can bear witness to the merit of their researches. The great mass of basalt (called whin sill) lies 522 BOCKS PRODUCED BY THE AGENCY OF HEAT. in a pseudo-stratum of most irregular thickness, enclosed among the strata of the carboniferous limestone series, generally in one particular part of the series, so that in the valley of the Tyne its place in the section is constant, and we think it occupies generally the same situation in Teesdale, though in Weardale another layer 6f basalt occurs. We cannot doubt that it was erupted from several local centres or lines, and that its thickness at different places was effected by their proximity to the eruptive channel. In the short space of six miles, from Caldron Snout to Hilton Beck, its thickness is diminished from 200 or 300 feet to 24 feet, and farther south it disappears totally. But to the northward the range is (interruptedly) continued to the sea-coast of Dunstanborough. No dikes pass from this mass (in Teesdale) into the rocks above or below ; so that a first view of the case suggests the belief that it was poured out as a mass of submarine lava upon the yet incomplete deposit of the carboniferous limestone. Professor Sedgwick, how- ever,* maintains that it was injected from below amongst these strata, and that it penetrated between the planes of the strata by violently uplifting them. The strata in contact are affected by the basalt in several ways, which may be well seen about the High Force. The subjacent shales are prismatized, so as to be mistaken for basalt, generally much de- bituminized, so as to become gray or whitened, and rendered brittle by condensation, but not much hardened. The sandstones are in several places highly hardened, rendered brittle and full of fissures, and much whitened. The limestones below the shale are remarkable for having their top bed full of iron pyrites. Those above, but not in contact with the basalt, are for a large tract of country totally changed from a full blue, hard, rather crinoidal limestone in the first degree to a pale blue, crystallized, soft marble, and in the extreme to a loose, granular, saccharoid rock, in which, nevertheless, some traces of organic remains (a crinoidal column) remain. But the most remarkable effect is the generation of garnets in the contiguous shale under the basalt of Cronkley scar ; a case analogous to the one described in connection with the dikes of Plas Newydd by Professor Henslow.f The igneous rocks themselves are chiefly a fine grained dark basalt, changing to a coarse grained variety of the same ingredients. Contemporaneous veins of very beautiful hypersthenic and augitic trap pass through the basalt in several points, and it is traversed by a few productive lead veins. The connection of several very remarkable and extensive basaltic dikes with this great "whin sill" has been rather assumed than * Camb. Phil. Trans. t GeoL Trans. BASALT. 523 proved. In fact, there is no evidence of any one of these dikes being traced into the whin sill, and as some of them pass into the upper coal measures, and one divides magnesian limestone, lias, and oolites, we prefer to consider them of different ages, though certainly- related to the same local centre of igneous expansion. Successive injections of similar igneous rocks, at remote geological intervals, seem to be indicated by the phenomena. These dikes pass in directions to the east north-east, east south- east, and nearly east, and the lines which they take are so straight through all sorts of rocks, their respective breadths, and the quality of the rock in each, so nearly uniform, though in these particulars they differ from one another, that, considering their extraordinary length, we may safely rank them as among the most remarkable phenomena of English geology. The Cleveland or Cockfield dike, in particular, ranges for seventy miles through the coal series, (where it chars the coal, hardens the sandstones, and debituminizes the shales,) the magnesian limestone, the lias shales and sandstones of the oolite series, which are affected like the coal system below. Generally it is a nearly vertical dike, but at Cockfield Fell is subject to oblique expansions of a singular kind. The dike which passes east north-east is remarkable for having a small vein of lead ore running by the south-east side of it, and for converting the shales through which it passes to the state of a soft, whitish shale, called pencil bed, like those in connection with the whin sill. It does not cut through the magnesian limestone. The magnificent cave of Staffa is fashioned in vertical prisms of basalt, between rows of which the eye fixes on the distant vision of lona. Over the cave the basalt is in smaller prisms, lying obliquely. 3C3 Fingal's Cave (Staffa). 524 BOCKS PBODUCED BY THE AGENCY OF HEAT. Melaphyre, Pyroxenic Porphyry. The history of this rock, which has a base of augite or pyroxene, holding crystals of felspar, is indissolubly associated with the name of Leopold Von Buch, who, by a series of observations, chiefly founded on a survey of the southern flank of the Alps, has been led to form the remarkable opinions 1. that the elevation of the eastern range of the Alps, since the tertiary epoch, was contempo- raneous with and dependent on the eruption of melaphyre ; 2. that the dolomites of the Alps were produced from ordinary limestone at the same time and with the same dependence. The line of dolomites and melaphyres extends (interruptedly) from Bleiberg to Lake Lugano ; but the occurrence of so many masses of dolomitic lime- stone in other situations than where melaphyre shows itself, must render inconclusive the inferences drawn from their connection in .the Alps. Neither is this connection always very evident. On the contrary, even at Lugano, it is rather near the augitic rock than in contact with it that the limestone is dolomitized. Von Buch's own map and sections * would hardly lead to the opinion that the dolo- mitization of the limestone was especially due to the presence of melaphyre. For between the dolomite and melaphyre of the penin- sula of Lugano, mica schist and another kind of porphyry intervene ; and on Monte Argentera, the limestone which lies upon the melaphyre is not dolomitized. De Beaumont admits that it is even rare to find the dolomites near Lugano in actual contact with melaphyre. It would, however, be unjust to Von Buch to reject the hypothesis on this account. He himself says it is to gaseous eruptions accom- panying the pyroxenic eruption that we must ascribe the alterations of rocks. The influence of these exhalations might be felt far from the main fissures occupied by melaphyre, and "De Beaumont generalizes the phenomena so as to refer the production of dolomite to the exterior line of fracture of the primary rocks ; that is, to the line which now divides the undisturbed from the disturbed rocks. The view is thus entirely changed, and certainly rendered more philosophical. Whatever may be its fate in this amended form, geologists will have been taught by it to investigate generally what connection there may be between certain phenomena of alteration of rocks, certain lines of disturbance, and particular erupted mineral aggregates ; and thus the field of research into the conditions of the local metamorphism of stratified rocks is greatly widened, and brought into nearer relation with the speculations concerning general altera- tions of the primary strata around granitic nuclei and axes of eleva- tion. * Ann. des Sci. Nat,, torn, xviii., pi. vii. POEPHTET. 525 Claystone. In the cliffs of Cory gills (Arran) are several clay stone dikes. One of these slopes at a considerable angle through the sandstone cliff, and, being very wide, shows a columnar structure in the middle rectangled to the plane of the dike; along the sides it is slaty. Between the columnar porphyry of Drumadoon and the Coves on the west side of Arran may be seen no less than five interpositions of claystone among the sandstone strata, mostly exhibiting a rude prismatic structure. Near Tormore is the celebrated arched vein or dike of claystone represented by MacCulloch, and considered as composed of ellipsoidal concretionary layers by Boue. It is redder and softer in the middle than at the sides ; it divides strata of red clay and white sandstone. Great variety of clay stones occurs in the Pentland hills.* Claystone Porphyry. Trachytic porphyry, (Boue,) clay porphyry, as it is termed by Jameson, occurs on the western shore of the Island of Arran in con- siderable variety. It appears in the cliffs in huge overlying masses, and on the sandstone shores in dikes of great width. At Drumadoon many interesting exhibitions of it occur. We extract the following brief notices from a journal of observations in 1826 : A dike (a) of clay porphyry 20 feet wide, ranging south 40 west, includes large modified felspar crystals, which are sometimes nodular in external figure. On the south-east side is a contiguous vein of greenstone. The porphyry encloses masses of greenstone ; it is not prismatic. A huge mass of clay porphyry, like a dike or rather interposed bed, dipping south, has 011 the south a layer of more basaltic aspect, the two being united in one specimen. In the fine range of clay porphyry columns at Drumadoon, which are 60 or 80 feet high, occurs a dike of greenstone passing in a line of double flexure obliquely through the pillars. At the base of these columns is a layer of more decidedly basaltic rock with few crystals of felspar, through which the same prismatic structure passes. Towards this great mass the dike (a) tends, and is said to join it. A very wide dike of clay porphyry, ranging north 60 east, (beyond the Coves,) has greenstone on each side, and also encloses greenstone. Amygdaloidal Trap. The Hill of Kinnoul, one of the most remarkable masses of trap rock in Scotland, rises near Perth, from out of the great area of red * Professor Jameson, Wern. Trans., vol. ii. 526 BOCKS PBODTJCED BY THE AGENCY OF HEAT. sandstones which lie against the primary strata of the Highlands. Its height above the plain of the Tay is stated by MacCulloch* to be 600 feet, and it shows precipitous faces to several quarters. The greater part of the hill consists of an amygdaloidal rock, whose basis varies from well-characterized basalt to wacke. The substances which impart to the rock its amygdaloidal character are, green earth, calcareous spar, quartz, and calcedony. Green earth, or chlorite, occurs in nodules generally small and round; it also invests the roundish nodules of calcareous spar, which are crystallized within but externally accommodated to the shape of the cavity in the rock, or to the crystals of quartz which sometimes line the cavity. The spar is sometimes crystallized at liberty in a cavity of quartz or The quartz is found to vary by several shades into agate and calcedony, which latter sometimes appears in a stalactitical form hanging downwards in the cavities of the amygdaloid. Alternating zones of quartz and calcedony sometimes appear in the same nodule ; amethystine quartz also occurs, and we have in Kinnoul almost every variety of angularly zoned agates. Veins as well as nodules of calcareous spar and quartz divide the rock, and more rarely sulphate of barytes, chert, and agate. Veins of heliotrope have also been found, but without the red spots. MacCulloch thinks there is not the least reason to doubt that the substances now filling the cavities of the amygdaloid have been introduced at some period since the cavernous aggregation of that rock from a state of lava. Shales and sandstones are hardened and altered, and much con- fused at their junction with the trap. A remarkable case of seeming prolongation of thin masses of the shale into the substance of the trap, so as to resemble veins, is described and represented by Mac- Culloch. f In these seeming veins the laminated texture of the schist disappears. Alternations of amygdaloid and sandstone are frequent about Oban. Wacke. Eespecting this softest of the trap rocks, we shall only observe, that in the Caltori Hill, Edinburgh, it forms part of those variable masses which sometimes may be called amygdaloid, sometimes por- phyry, and not unfrequently assume the aspect of breccia ; being likewise traversed by numerous small veins or strings of calcareous spar. In the superior and eastern parts of this hill wacke alternates with bituminous shale and nodules of argillaceous ironstone, in many repeated strata dipping to the east. At the surfaces of junc- * Geol. Trans., vol. iv. t GeoL Trans., vol. iv., pL xi. PITCHSTONE. 527 tion there sometimes appears a gradation from one rock to the other ; and it does not appear that any decided marks here occur of the action of heat upon the shales. Pitchstone. As hefore observed, pitchstone occurs in the Isle of Arran both in dikes and interposed beds among the sandstone strata. The west- ern coast is particularly interesting in this respect. The same cliffs which exhibit so many claystone masses alternating with sandstone, contain also parallel short bands of pitchstone probably connected with the neighbouring dikes. One of these dikes, about 30 feet wide, is curiously mixed with hornstone, and for the most part bor- dered along the sides by greenstone. The disposition of these substances in the fissure will be understood by reference to the hori- zontal plan, fig. 364, where the letters H, p, and G, are placed against the hornstone, pitchstone, and greenstone, respectively. The pitchstone is generally of a dark green colour, fissured longitudinally into rude prisms, which are joined transversely at about two feet distance, or concreted into smooth conical masses. It seems to pass gradually into the hornstone, which is laminated parallel to its bounding surfaces. The dike appears in one place to deviate from its vertical course and to go under a portion of the sandstone. A greenstone dike, which is nearly right angled to the course of the pitchstone, is shifted by it. In another dike, one side is yellow pitchstone closely approximat- ing to claystone, within this light green and red stripy pitchstone, then siliceous splintery stone in irregular masses (hornstone), and the opposite side is greenstone. Another of these curious dikes is green pitchstone on each side, then red pitchstone, and in the middle dark gray hornstone. The pitchstone bed at Corygills is 15 feet thick ; a dark green or black rock, enclosed between strata of sandstone, which are hardened towards the junction. The pitchstone is marked by lines parallel to its nearly level surfaces, and these are crossed by the smooth distant vertical faces of prisms. The lower part is porous ; between it and the sandstone beneath is a white crumbly or frag- mentary mass soft as steatite, which it much resembles. 528 EOCES PKODTJCED BY THE AGENCY OF HEAT. Trap Tuff. Porphyntic Breccia. Volcanic Sandstone. Re-aggregations of the disintegrated or fragmented materials of trap rocks are generally known under the vague name of trap tuff, and compared with volcanic tuff, sometimes without much reason. . Amongst the slaty rocks of Cumbria, in Glen Coe and Ben Nevis, fragments of felspathic and porphyritic rocks are frequently found united into a solid breccia ; under Arthur's Seat and in the Calton Hill recomposed irregular strata, chiefly derived from fragmented rocks of igneous origin, appear associated with ordinary greenstones, porphyries, and basalts. In many instances these have no just claim to be ranked with the pyrogenous rocks, but should be transferred to the class of tumultuary and local aqueous deposits : the circum- stance that the principal portion of the ingredients is of igneous origin, is not probably confined to these rocks, but is often, perhaps with as much truth, ascribed to the whole mass of sedimentary deposits from water. In the vicinity of Oban, in juxtaposition with some interesting amygdaloids and altered shales, sandstone beds, composed of the grains of disintegrated trap rocks, are found resting on conglomerate, amongst whose pebbles are granite, porphyry, quartz, red and white amygdaloid, fine grained basaltic trap, sandstone, jasper, &c. Murchison found, along the South Wales border, many examples of the occurrence of sandstone composed of the ingredients of trap rocks. A little removed from the steep slopes of the Wrekin and Caer Caradoc, rocks of this kind occur in beds, and contain organic remains, but in all respects of composition strongly resemble green- stone. This was noticed by Aikin. At the southern extremity of the Wrekin, the stone is of a dark green colour, and is evidently composed of the ingredients of greenstone and syenite with a few scales of mica. Near the Caradoc these beds contain much decom- posed felspar. They have been attributed to submarine eruptions of volcanic substances in such a state of disintegration as to mix with the sea water, and be diffused over considerable breadths of the bed of the sea. ORIGIN OF MINEBAL VEINS. 529 CHAPTER XVII. MINERAL VEINS. The circumstances attending the occurrence of mineral veins in the rocks, their intersections with each other, and the arrangement of their mingled metallic and sparry contents, have been sufficiently studied to ascertain that these valuable elements in the adaptation of our planet to the wants of its inhabitants have been subjected to a great variety of processes depending possibly on one general law, but greatly modified both in combination and energy by local and periodical conditions. In the vague language of imperfect science, v?e say, many causes, separate or variously combined, have been con- cerned in the production of mineral veins ; and it is probable that the most advantageous mode of investigating their origin, consists in the attempt to infer from the mass of facts already brought together, what are, respectively, the spheres of action and limits of intensity belonging to the several processes concerned ; and afterwards, from a more general contemplation of these processes in their various degrees of combination, to rise to a comprehensive notion of their connecting laws and general cause. This is not the mode usually followed by writers on mineral veins. Neglecting the general fact of the complication of the phenomena, they have been mostly anxious to try their bearing individually, or in mass, upon the perfectly general question of igneous or aqueous agency, and thus nothing was explained. A vast abundance of minute information on veins has been irrecoverably wasted ; and the experienced miner laughs at the reasoning of the half-informed mine- ralogist, contemptuously rejects his theory of veins, and contents himself with believing that the facts are inexplicable. This disso- ciation of observers and reasoners is the true cause of the compara- tively small advantage which has been derived to geology from the immense and various mines of the British Isles ; on the one hand we have the greatest possible variety of phenomena, on the other the full extent of the resources of chemical and mechanical philosophy, but these have not been combined. If the zoological principles of geology are better established and more fertile in deductions than the mineral principles, it is not because our knowledge of organic nature is more advanced than the science which treats. of the con- stitution and agencies of inorganic matter, for the contrary, perhaps, is true, but because in the one case the ancient effects and the mo- dern laws of action have been brought into mutual illustration, in the other deprived of all connection. 2M 530 MIKEEAL YEOTS. In order to prosecute the investigation according to the principles which we have stated to be the best, we must limit our inquiry to those subjects most distinctly connected with metallic accumulations in the rocks. To support inferences concerning the general laws of processes which have produced mineral veins, we may with great advantage include the history of basaltic and granitic, and porphy- ritic dikes ; but for the discovery and estimating of the processes themselves only those effects must be examined in which they are especially concerned. Though in some instances the distinction between rock dikes and mineral veins be imaginary, they are in general clearly contrasted by the nature of the substances which they contain. In the former case, crystallized minerals of the same kind as those great interior masses of consolidated rock from which they often are evidently ramifications ; in the latter metallic substances which are mostly not known to exist in nature except in these situations and in other very similar or distinctly related to them by position, and crystallized or earthy minerals, seldom of the same kind as those which occur in any of the rock dikes. To this general rule quartz is one of the most striking exceptions ; yet even in this instance it is remarkable that the quartz of veins is of a different aspect from that mingled with the ingredients of granitic and trap rocks. We must therefore take the presence of metallic matter and certain nonmetallic sub- stances usually connected therewith, and commonly called vein-stuff, as the leading characteristic of the mineral veins whose history we are now to examine, and connect with these all other cases of metal- lic aggregations or occurrences of the vein-stuff which seem referable to the same or analogous processes. This view embraces the following points of research : 1. What substances are found in mineral veins and repositories. 2. The manner of their aggregation or mixture. 3. The situations of their occurrence. 4. The relations between frequency, arrangement, and contents of the veins, nature, age, and position of the rocks in which they occur. Substances in the Veins. what Substances, &c. The simple minerals which occur in veins and analogous situations are far more numerous than those which are found as component parts of the rocks. Igneous rocks, and espe- cially those of modern volcanic origin, hold a very great variety ot nonmetallic substances, some of which also occur in veins ; but it is almost exclusively in this latter that we are to seek the metals in their pure state, or alloyed with one another, or mineralized by com- bination with sulphur and other combustibles, with oxygen, chlorine, and other gases, or converted into salts by union with various acids. METALLIC SUBSTANCES. 531 Every elementary substance yet discovered by chemists exists in the earth ; and it is probable that none of these are entirely absent from the solid contents of mineral veins, though this has not yet been shown to be the case for iodine and bromine, which seem universally present in the modern ocean, and azote, which appears in an especial manner devoted to the atmosphere and to the organic portion of nature. Alloys. The metallic substances seldom occur pure, sometimes in alloys, similar for the most part to those now producible by the che- mist, 'as silver, antimony, cobalt, nickel, iron, with arsenic ; silver and nickel with antimony ; lead, gold, silver, and bismuth with tel- lurium; silver with mercury; platinum with gold, &c. The only known circumstance which stands as antecedent to the production of such alloys is heat, produced by either chemical or electrical action ; and perhaps there is no single fact connected with the theory of veins on which the conclusion of the influence of heat in their pro- duction might be more securely based. The rarer occurrence of pure metals affords an argument perhaps of less force, but perhaps we may draw the same inference from the very numerous class of metals mineralized by union with combustibles, as sulphur, phosphorus, carbon, selenium, &c., the formation of which, according to the state of our knowledge of chemical forces, is in many instances a direct compound of heat, as the solidification of them is, in other instances, the result of cooling. Oxides and Salts. We cannot apply this general argument to the case of the metallic oxides which are very prevalent in veins ; be- cause, in the first place, these are produced under various relations to heat, moisture, and contact with gaseous substances ; and, secondly, have various degrees of permanence when exposed to high tempera- tures, either separately or combined. Neither have we any general conclusion to present concerning metallic salts, which likewise are not rare in veins, since these are also in the same way various in their origin and degree of permanence. There is besides a difficulty attaching to this branch of the subject arising from the interesting fact that, in very many instances, metallic oxides and salts are deriv- ative compounds from sulphurets and other primary combinations ; and when this is very evidently the case, they are called epigene. This may be said to be even frequently the case with oxide of iron, carbonate of copper, and probably carbonate, phosphate, and other salts of lead. Nonmetailic Minerals. Besides the metallic ores which impart to many veins their most striking, if not most constant characters, various earthy minerals lie in these repositories, and, as will after- wards appear, under certain definite relations to the enclosing rocks as well as to the included metals, and with a less distinct dependence on the local situation or mining district. These earthy substances are 532 MINERAL VEINS. usually called the gangue, vein-stuff, or matrix of the ore. Gene- rally they are crystallized, as quartz, fluor spar, calcareous spar, phosphate of lime, the sulphate and carbonate of barytes, strontites, &c. ; sometimes appear massive, as quartz and several other minerals when the vein has no cavities in it ; and sometimes the vein- stuff is entirely soft argillaceous matter, of different aspect in different mining districts. We are not aware that these soft kinds of vein-stuff have ever been analyzed, though probably some curious results might reward the labour. The Cornish mines would furnish many examples. Rider. In some veins masses of the neighbouring rocks are en- closed and penetrated to a great extent by little strings of the ore and spar, so as occasionally to be worth the trouble of working. The vein is said in this case to bear a rider. It, in fact, sometimes becomes under these circumstances a double vein. More rarely pebbles and other marks of watery action are stated to occur in soft veins. Mode of Aggregation of the Ingredients. In this respect there is a variety of appearances which deserve especial notice as indicating some of the conditions under which the vein was filled. In some cases, for instance, the whole breadth of the vein is occupied by one kind of substance, as lead ore, or quartz, or sulphate of barytes ; in other instances, the metallic matter is in- terspersed in small masses through a general basis, as quartz ; but, generally, the different substances which fill the vein are ranged in a definite order of succession from the sides of the vein toward the middle, in which, commonly, the metallic matter occurs in an irre- gular vertical table called a rib of ore. These variations are best observed in the proper veins, but are also to be noticed in the nests and detached masses of ore and vein-stuff which sometimes occur in the vicinity of the veins. General idea of a Mineral vein. The ordinary notion of a mineral vein is well exemplified in some Derbyshire specimens, not rare in collections, which, when cut across, show in the middle masses or a continuous rib of galena, and on each side of this, to the extreme edges of the mass (or narrow vein), layers of flour spar and car- d bonate of barytes in frequent alternation, all the materials being crystallized together without leav- ing any cavities, yet preserving their own character of structure. Thus, in the diagram, a is the middle rib of galena, b b, c c, the alternating bands of barytic spar and fluor spar ; d d, the masses of rock which enclose the vein, are called the walls or cheeks of the vein. HOW DEPOSITED. 533 Supposed Successive Deposition of the Substances. The Contempla- tion of these specimens seldom fails to impress upon the mind an imperfect conviction that the several bands of mineral substances were deposited on the cheeks or walls of the vein in succession, the middle being filled last of all ; and this theoretical notion has been illustrated by comparing a mineral vein to a narrow gallery whose walls were covered by many successive coats of plaster of different colour and composition. Werner adopted the notion of the unequal antiquity of the vertical layers of the vein so implicitly as to speak of the middle ribs as always of less antiquity. It is difficult to resist this impression, especially when, in addition to the circumstance of the succession of the laminae, we observe that these laminse are so crystallized as to turn their free terminations towards the centre of the vein, and in that direction to imprint the next layer with their own forms, just as crystals forming in a vessel shoot their points toward the part still remaining liquid, and in that direction are covered by the subsequently formed crystals. Very similar infer- ences are suggested by certain agates, and more distinctly by geodes in basalt, and the crystallized cavities in limestones, in the interior of shells, &c. ; in which cases the hollow towards which the crystals pointed still remains. Reasons Against this Notion. Yet this first impression loses some- what of its force when, instead of confining ourselves to a cabinet specimen, we examine the whole extent of a mine ; for here in the first place it is very often found that the regular succession of min- erals from the side to the centre is a limited though repeated pheno- menon ; that the rib of ore is of short horizontal, and sometimes still shorter vertical extent, diminishing to nothing, or diffused in small grains through the contiguous spars ; that different metals are found in the same vein at different depths and at distant points along its course ; and that both the quantity of metal and the presence of spars are dependent on the hardness, and perhaps on some properties imparted by the chemical nature of the rocks which the vein divides. Instances of this will be given hereafter. Chemical Reasons. The phenomena of crj^stallization before alluded to can hardly be thought to prove the successive introduction of the mineral laminae into the vein ; though very probably they do demon- strate the order of crystallization of these substances. In some cases we observe indications that one kind of mineral has been formed round another as a nucleus ; as for example, sulphuret of copper round icosaedral iron pyrites in a part of Caldbeck fells, Cumberland, and more frequently in many places carbonate of copper and carbonate of lead round the sulphurets of those metals. It is very often the case that the metallic matter of the vein is collected into the middle and forms there a distinct tabular mass, called a rib 534 MINERAL VEINS. of ore, more rarely it is disseminated in the gangue. Generally, only one kind of metal abounds in the same part of the vein, but the same vein may yield lead above and copper below, copper above and tin below, or lead in one place and copper in another. The observation is frequent that ore is collected into certain vertical portions of a vein which are worked above and below level, and between which little but vein-stuffs is found in the horizontal drift. There is a vague notion amongst miners, that veins are most productive in the deep, and it is at least probable that they are less rich very near the surface. Association of Minerals. Werner insists on the fact, that certain associations of minerals can be traced in veins. He notices the con- currence of lead glance, and blende or calamine, and copper pyrites ; of cobalt, copper, nickel, and native bismuth ; of tin, wolfram, tung- sten, molybdena, and arsenical pyrites ; of topaz, fluor spar, apatite, schorl, mica, chlorite, and lithomarge; of brown ironstone, black ironstone, manganese, and heavy spar. He says where tin occurs, ores of silver, lead, and cobalt, and vein stuffs of heavy spar, calca- reous spar, and gypsum are rarely found. Cinnabar and other ores of mercury scarcely ever occur with the ores of other metals, except iron ochre and iron pyrites. Roiled and Fragmented Masses. That fragmented masses of the neighbouring rocks should be found in mineral veins, cannot be thought surprising. It is a common occurrence in mining districts, both of primary and secondary rocks. Thus gneiss at Joachimsthal, clay slate in Cornwall, limestone in Cumberland, are included in the veins. Werner mentions a vein in Danielstollen at Joachimsthal, fourteen inches wide, which, at one hundred and eighty fathoms depth, was almost entirely composed of rolled pieces of gneiss, some of them nearly spherical. In the Stoll Kefier, near Riegelsdorf, a vein of cobalt was cut through by another vein of sand and rolled pieces. These examples seem satisfactory, but we must always be careful to discriminate between rolled pebbles and concretionary masses. General Forms of Veins. Mineral veins are usually distinguished by miners into several kinds, according to their general form and direc- tion, because these circumstances are the most influential in the arrangement of their works. Rake veins, the most common and char- acteristic, may be considered to fill long, narrow fissures, which pass in a vertical or highly inclined direction downwards from the surface through a great thickness of the subjacent rocks, whatever these may be, and preserve nearly the same angle of inclination and the same linear direction through their whole course. Pipe veins are also highly inclined, and pass downwards in the same manner, but they rather resemble irregular chimneys than fissures, and are subject to great DISTINGUISHING FOEMS OF. 535 swellings and contractions of their diameter. They sometimes pass downwards along the surfaces, and in other cases penetrate through the substance of the strata. The mines in the neighbourhood of Ecton, in Staffordshire, are on pipe veins. Perhaps we may give the same name to the irregular cavity of copper ore, which forms the celebrated Parys mine in Anglesea, and to the iron mines of Danne- mora, in Sweden. Flat veins or streaks, as far as we are acquainted with them, seem hardly to deserve a special name, being only por- tions of rake veins which have been changed in their inclination, and made to pass for limited distances parallel to the beds. In the limestone districts of the north of England, this happens principally in connection with certain limestone beds. Williams has a title of Gash veins to express such as range for considerable lengths, like rake veins, but are wide at top, and grow narrower downwards, till they entirely vanish. This is a rare case ; though Werner's opinion seems to be that many veins grow narrower downwards. strings. Perfect parallelism of the sides or walls of a rake vein, which is the most regular of all, is a rare phenomenon. Most com- monly, indeed, there is a definite boundary to the mineral masses presented by the rocks on each side, but this is only on the great scale ; and the operations of mining disclose to us innumerable cracks and fissures in these boundary walls, which, when filled by metallic or sparry matters, are called strings, and are frequently worth the labour of following even to great distances from the parent vein, if, indeed, we are entitled to use this hypothetical expression. The notion of miners generally appears to be, that these strings are to be viewed as feeders of the vein, and in proportion to their frequency in many instances, is the productiveness of the vein. In the accompanying diagram, the vein is re- presented as sending out small branches or strings into the neighbouring rock. A rock thus penetrated by strings is sometimes said to be ridered, just as the masses which are often included in the vein, and the walls which bound it, are called rider. In many rocks these ridered parts are very greatly altered from their original state. It sometimes happens that, in passing through rocks of various hardness, as limestone, shale, &c. the veins turn flat for a short distance on the hardest and most connected beds, (as, for example, on the Tyne bottom limestone of Cumberland,) and afterwards continue their course. These flat parts usually send off strings into the limestone, which may thus be ridered to a considerable distance. Disseminated Veins, &c. Sometimes the mineral is disseminated through the parts of the rock adjoining a vein, or collected in small nests and other closed cavities. This happens not only in the 536 MINEEAL YEItfS. Cornish mines, in killas and granite, but in those in the mountain limestone tracts of the north of England, and even in magnesian limestone. Generally speaking, we may be sure that this metallic impregnation is so related to the veins, that it is an effect of the same agent. Whatever filled the veins, also transferred to small distances from them some of their constituent minerals. Certain metals and ores are more liable than others to this lateral diffusion. Native silver, silver glance, red silver ore, native copper, tin ore, iron pyrites, and red iron ochre, are specially noted by Werner as occur- ring in this way. He says, copper ore, pyrites, and lead glance seldom exhibit this effect. The assertion may be disputed as to galena, which is found, as well as blende, and bitumen, and calc spar, and quartz, in closed cavities of shells, in mountain limestone, and in other strata. Tin Floors, Siocit work*, &c. The dissemination of tin ores through some of the rocks of Cornwall, is noticed by Hawkins, under the title of tin floors.* He observes, that the whole tenement of Botallack is said to be full of tin floors. At Zinnwald, mineral beds or floors have long been the object of mining adventure. There granite alter- nates with the tin floors, which consist of quartz and mica, with tin ore, fluor spar, and wolfram, quartz and mica with tin ore, &c. At Breitenbriinn a floor of this kind has been very extensively worked in a gneiss rock. The stockwork of the German miners is to be considered as a mass of rock impregnated with metallic matters, in numerous small veins, which come together irregularly, so as to make particular parts extremely rich. The working of such mineral repositories is directed by quite other principles than those which serve for straight veins of definite magnitude. The stockwork is generally opened like a vast quarry, and the excavations are prosecuted irregularly in the most favourable directions. Perhaps the copper mine of Pa^s mountain in Anglesea, the iron mine of Dannemora in Sweden, the tin ore mine of Geyer in Saxony, are examples of immense stockworks. Werner, however, appears to have considered the stockwork as peculiar to tin ores. Relations of Veins to each other. The influence which veins exert on each other may be in some measure ascertained by an examination of the phenomena at the points where they come into contact or cross each other. At these points it is very often found that the quantity of ore is suddenly increased to a large amount, and for some distance, either in one or - * Geol. Soc. of Cornwall Trans., vol. ii. EPOCHS OE. 537 both of the veins. Many veins are productive only near such points, or yield there peculiar ores and minerals. This does not depend upon the enlargement of the vein merely, but is one of many facts which appear to indicate the agency of certain electric attractions in the disposition of the materials of mineral veins. We have heard miners say, that in certain cases neighbouring veins are subject to a kind of reciprocity, so that they are not both productive in the same ground, but where one is rich the other is poor ; but this cannot be established without a very large collection of instances carefully observed. Age of Veins. The intersections of veins likewise furnish us with another well-ascertained class of facts, which throws light on the relative epochs of their production, independent of the evidence on this subject furnished by the rocks which they divide. When two veins cross, it almost invariably happens that one of these cuts or is continued right through the other, as a wall is sometimes continuous through another wall of brick from top to bottom. Thus, a vein of copper ore may cross and cut through a vein of tin ore, a vein of lead ore may cut through a vein of copper ore, and all these be cut through by some other sparry vein or porphyry dike. It is supposed, by almost every writer on the subject, that the relative antiquity of the veins which thus intersect one another may be immediately determined ; and that in every case the vein which is cut through is the oldest of the two. Werner took this as the basis of his classi- fication of veins, and most practical as well as theoretical miners agree in his views ; but they are nevertheless controverted upon various grounds, and as the question is of great interest, it will be useful to present a short connected view of the facts bearing upon it. We cannot make a step in this argument, except upon the admis- sion that the veins are posterior to the rock which encloses them ; in other words, that the space in which the mineral masses of a vein lie, once existed as a fissure in the rocks, and was subsequently filled up by the accumulation of the sparry and metallic matters. This is generally supposed by authors to be a self-evident proposition. It is equally allowed by the Wernerian and Huttonian hypotheses ; and practical miners can with difficulty be made to understand that any doubt has been entertained on what seems to them so plain a truth. Phenomena in Cornwall considered. But the embarrassing pheno- mena of the granitic and mineral veins in Cornwall have created amongst some of the geologists of that district a strong suspicion, that veins are not to be pronounced of different antiquity on account of the circumstances of their intersection, nor to be considered as filling fissures at all ; but that the veins and the rocks which enclose them are of the same origin. Even the common fact of veins passing through slate into granite, does not appear to them subversive of 538 MINERAL YELN'S. their views, which would reduce to one epoch and one origin the most dissimilar chemical and mechanical phenomena. This insulated opinion has been generally neglected, as opposed to the actual state of knowledge and inference on the subject, but as it undoubtedly contains at least a portion of truth, we shall trace a few of the circumstances on which it is founded. Those who favour the opinion in question, must not be surprised at our omitting altogether what may perhaps appear to them the strongest argument of the whole, viz. the mechanical difficulties attending the generally received view, that veins were originally fissures of the rocks, because these diffi- culties have been in some cases surmounted, and in the rest are certainly more than balanced by others of a different kind affecting the Cornish theory. It is, besides, no argument for one theory that another is beset by difficulties which are left unexplained in both. in the Neighbourhood of a Vein. It is a general fact, that the walls of a vein partake in some degree of its characters, and that effects, apparently depending on the vein> propagate themselves into the neighbouring rocks. Thus the walls become more indurated, more crystalline, and for considerable distances are filled with the matters of the vein ; and even the very substance of the rocks is impregnated with mineral combinations. In a country where the veins are numerous, large masses of the rocks may in this way be ridered, as it is termed in the north of England ; and if such a gradation of characters could be relied on as a proof of contem- poraneity of origin, this may in a few cases lead to the conclusion, that the veins and rocks are coeval. But what is the true conclusion on this point ? Is it not that these effects are locally related to the veins, because they are a con- sequence of their influence, or rather of the agency which occasioned them ? That the ridering of the neighbouring rocks is coeval with the production of the vein may be allowed ; but because these rocks are clearly defined from the veins, and fragments of them are enclosed in the veins, and the mineralizing influence which they have suffered obviously depends on the influence of the veins, we cannot hesitate to admit that these latter are of separate and subsequent origin. These facts are similar to what occur in other mining districts, where the stratification and consecutive depositions of the rocks divided by veins is perfectly evident, and where, therefore, contemporaneity of the veins is impossible. in Different Rocks. It is found, that when veins divide different sorts of killas or other rocks, their contents vary in some incon- stant manner, according to the nature of the rocks ; and, therefore, it has been sometimes argued, that the production of the one is dependent on the other. The most usual notion on this subject is, that the veins may be viewed as secretions from the rocks ; and by APPEAKANCES AT THE CEOSSING. 539 some this is supposed to have happened after the production of fissures ; by others, by a mere internal separation of the parts of the mingled metallic and earthy mass. This notion of the slow separation of the ingredients of rocks is in accordance with the principles and facts of chemistry, and must be often appealed to, if we would explain by true causes the phenomena of mineral veins ; but with respect to the question before us it is indecisive, and may with equal propriety be applied to veins of fissures and veins of segregation. The same electric attractions between certain minerals in veins, and certain rocks about them, obtain in the secondary strata, as in the slates and granites of Corn- wall ; but if the pre-existence of fissures in the former is certain, why shall we deny it in the latter ? Contemporaneous Veins. There are combinations of minerals in masses of various figure, which, upon very good grounds, are ad- mitted to be contemporaneous with the rocks in which they lie ; and if we choose to call by the name of veins all such distinct com- binations of minerals, these certainly are contemporaneous veins. When in granite, greenstone, &c., we find particular portions either linear, tabular, globular, or in any other figure, which have a different proportion of ingredients from the other parts, and in consequence become conspicuous and distinct, except at the edges, which gra- duate without any sign of fissure into the ordinary mass of the rock ; these may certainly be pronounced contemporaneous veins, and they have been produced by a process of secretion or segregation during the crystallization of the rock. These cases are perfectly distinct, and by contrast place in still more striking light the true relative age of veins of fissures. In some instances veins of calcareous spar or other minerals lie wholly included in limestone masses, and these are properly called veins of segregation ; but they are not contemporaneous veins, for they have clearly been fissures filled at some period since the consolida- tion of the rock ; and the proof is, that shells, corals, &c., are split and sometimes displaced by these sparry veins, which undoubtedly occupy cracks left by the shrinking of the rock in the process of con- solidation. Upon the whole, then, allowing every just latitude to the doctrine of contemporaneous veins, we must admit that the greater number of veins are posterior to the rocks which enclose them. intersection of Veins. This granted, we may return to the inter- sections of veins. The most simple case is when two straight veins cross without any change of direction, or any lateral displacement ; and the order of effects appears to be the production of a fissure, and the filling of this by a vein which was afterwards broken through by another fissure, and this, in its turn, received another mineral 540 HINEEAL VEINS. vein. It seems difficult to doubt the truth of this explanation ; for if the vein which cuts through the other be subsequent to the fis- sure in which itself lies, it must also be subsequent to the vein which that fissure divides. The occasional complication of the problem by the number of intersections does not at all change its nature. Appearances at the Crossing. There are, however, two things to be attended to, which require further consideration. It is some- times observed, that the vein which upon this theory is the oldest suffers a particular kind of accident at its junction with the other. It is divided into several branches on one or both sides of the cross veins, and these branches enclose portions of the neighbouring rocks. There is some difficulty in this case, however it be considered, and we must demand more exact accounts than are usually met with of these facts before attempting to reason upon them. The coincidence of this splitting of a vein with the crossing of another vein may often be only accidental ; for such splitting frequently occurs in a wide vein, far from any cross course. The fissures which have received the mineral veins are in most cases accompanied by slips or dislocations of the strata in a vertical direction, and the veins are of course subject to the same accidents of displacement. When two veins cross, and both are vertical, the lines of bearing of the two portions of the displaced vein must remain coincident after the fracture. If the divided vein be not vertical, its separated portions will have their lines of direction parallel, but not coincident ; and in any horizontal plane they will appear to have sustained a lateral movement. Thus in the diagram, fig. 367, the cross vein a and the divided vein b are both vertical ; but the divided vein c is inclined in the direction of the arrows, and its apparent lateral displacement is really due to a vertical move- ment. If two divided veins are inclined in opposite directions, and be dislocated by the same cross vein, they will appear to have moved laterally in opposite directions, as c and d. Were we to include the cases of the inclined cross veins, and also those where the inclination of these veins varies both in amount and direction, the results would become too complicated for explanation without mathematical symbols ; and we must, besides, remember that the displacement of the strata is really very seldom in a vertical direction, but generally accomplished by an angular movement from some fixed point, or round a virtual centre. We must, therefore, be very slow to admit the difficulty of the problem of the displacement of the solid masses of the earth as an argument against the received GEOGKAPHICAL EELATION OF. 541 opinions concerning mineral veins, for this principally depends on the want of precise and sufficient data. Several remarkable cases which occur in the mines of Cornwall have been simply explained by Mr. Lonsdale, and there can be no doubt that the application of the principles of solid geometry to other complicated phenomena of that interesting region will gra- dually remove much of the mystery which has been supposed to hang over them. Geographical relation of Veins. Though, properly speaking, there is no real connection between mineral veins and the external physical configuration of the earth, yet, as this configuration is connected with peculiarities of internal structure, it is generally found, as Werner long ago indicated, that mining districts are almost entirely confined to the vicinity of moun- tains or elevated land, because in these situations the rocks were most dislocated by slips, and divided by fissures at the period of their elevation. It is not the absolute height of the ground, but the circumstance of its having been much exposed to subterranean convulsion that determines the prevalence of mineral veins. The rich mines of Cornwall are in comparatively low situations, but they are all in the vicinity of erupted and elevated rocks. There appears to be no limit either of height above or depth below the sea, which defines the productiveness of veins, though in some countries the higher and in others the lower situations are most favourable. It is sometimes found that the contents of a vein vary with the depth, without any particular geological conditions ; as, for instance, in Cornwall copper is prevalent in the mines at greater depths than tin, and in the slate tract of Cumberland veins which bear lead near the surface yield copper in the deep. In other cases there appears a peculiar determination of the metallic ingredients to particular situa- tions. The mines about Ecton yield copper ; those of Derbyshire generally lead ; in the Pennine chain the veins generally yield lead, but toward the eastern and western limits of the district copper becomes less uncommon. The length of a vein of fissure is perhaps hardly in any case cer- tainly known ; because, when it ceases to be worth working, it is for all the ordinary purposes of mining said .to be dying out, or cut out, or ended. The richest veins are productive for limited lengths, but the fissures which they fill may be, and often are, extended far beyond the spaces occupied by metallic impregnations. Some of them are known to extend, and to be productive for many miles in the Harz, in Cornwall, and in the north of England. The width 542 MINERAL VEIIfS. is various in different veins, but generally nearly constant in the same vein. A width of twenty feet is very unusual. Most veins are less than six feet wide. Directions of mineral Veins. There is a peculiar geographical rela- tion of veins which is very difficult to understand, but which is so general that it may eventually be of the greatest value in correcting and perfecting our theories concerning them. This is the general direction of the veins. The most general direction of the great dikes and faults in the north of England may perhaps be denned to be nearly east and west. But this is much more certainly true with respect to the mineral veins of the limestone districts of Weardale, Allendale, Alston Moor, and all the mining districts of Yorkshire ; and it is equally recognized in the primary tracts of Cumberland, Westmoreland, and Lancashire. This is so general a fact, that the east and west veins are called right running veins, while the few which range more nearly north and south are called cross courses. These latter are seldom rich in metal. They often cut through and shift the right running veins laterally, as both of them shift the strata vertically. There is often to be observed a sort of compensa- tion in the dislocating effects of veins. In Weardale most of the veins throw up to the north, while the parallel courses in Allendale and Alston Moor throw up to the south. The lead veins of Flint- shire and Cardiganshire have the same east and west direction, and so have those of Mexico. The lodes and veins of Cornwall are most generally east and west veins, or nearly so; and these, according to Mr. Game's* excellent Memoir, are the oldest veins in that district, being traversed by the oblique veins and by the crt>ss courses elvans and flukans. But not all the east and west lodes are .of the same age, the tin being older than the copper ; neither are all the east and west tin veins of one age, for those that underlie to the north are generally traversed by those that underlie southwards. These curious generalizations are not to be overthrown by particular discordances. Their value may one day more fully appear, and they are certainly supported by ana- logous though less varied occurrences in other countries. Directions of Veins of different Antiquity. The general order of their dates may be thus expressed : 1. Oldest, east and west, tin veins underlying to the north. 2. East and west, tin veins underlying to the south. 3. East and west, copper veins generally east to south. 4. Oblique or contra copper veins, generally east 30 to 45 south. 5. Cross courses not metalliferous, north and south. 6. Copper lodes of more recent date and lead veins. 7. Cross flukans or clay dikes nearly north and south. 8. Slides in all directions, but generally east and west. * Trans, of GeoL Society of Cornwall. CONNECTION OF ITSSTJBES AND MAIN JOINTS. 543 The porphyritic and other dikes called elvan courses are very generally divided by the veins, and seem to be of greater antiquity. Werner has observed this geographical relation of mineral veins, and states the two following cases. In the mining district of Freyberg are two classes of veins very different from one another. One of these classes consists of veins which run from north to south. The veins of this contain lead glance, black blende, iron, copper, and arsenical pyrites, quartz, and brown spar. This is the oldest vein formation. The second class of veins, which always traverse the former, and are never crossed by them, contains lead glance, radiated pyrites, heavy spar, fluor spar, and quartz. They strike between the sixth and ninth hours of the mining compass (east to south-east) . The mining district of Ehrenfriedesdorf contains veins of tin and silver glance. The tin veins are always traversed by the silver. The direction of the first is between the sixth and ninth hour (east and south-east), that of the last from the ninth to the third hour (south- east, south, south-west). Another Geographical Relation. There is observed in some mining districts another remarkable relation of metalliferous veins to geo- graphical lines. Though in the north of England the most frequent direction of the veins be east and west, the mining districts seem rather to be ranged in lines from north to south. The nature of this relation will be more easily understood, if we add that both in Cornwall and in Cardiganshire, where the veins are also most fre- quently east and west, Mr. J. Taylor has observed lines of greater productiveness ranging nearly north and south across the bearing of the veins. These curious notices suggest the inquiry whether the lines of productiveness are dependent on any principal axis of dislo- cation or on the occurrence of cross courses. The former case seems to be vaguely indicated by the phenomena in the north of England. Perhaps the latter may be more applicable to Cornwall. Connection of Fissures and Main Joints. The remarks on the joints of rocks in pp. 40-43 may be referred to as sufficient to show the importance of studying their direction in connection with that of the fissures of mineral veins. It is certain that in the limestone dales of the north of England mineral veins are sometimes directed along the master joints of the rocks, also that in the slate tracts veins and dislocations range along the cleavage planes of the slates. (Craven.) Dr. Boase has noticed the same thing in the slate tract in Cornwall, and such observations will doubtless be multiplied. Mechanical considerations might have led us to anticipate this result ; for the main joints and cleavage planes would often be the lines of least resistance, and yield more easily 544 MIKEKAL YEINS. than other parts to any eruptive or depressing force applied to the planes of stratification. The direction of the master joints is cer- tainly definite over large tracts of country ; and if we should find eventually that mineral veins have commonly taken the same course, their regularity will no longer be an argument against, but an addi- tional evidence for the vertical movement of the masses. Relation of Mineral Veins to the Rocks which enclose them. The relation of mineral veins to the rocks which enclose them offers a wide field of inquiry, which has been much studied, and yet is very little understood. It is difficult to distinguish clearly between the accidental and the necessary association of the phenomena of veins and rock masses. It is perhaps hardly possible at present to form a satisfactory opinion as to the amount of effects produced by causes acting from distant centres of force. We are in ignorance as to the subterranean operations of electrical and calorific agents still constantly going on ; and to these theoretical difficulties must be added the unconquerable impediments to accurate and varied obser- vation of the facts on which inferences are to be founded. Minute analogies of the relation of veins to the adjacent rocks would there- fore at present be very unsatisfactory and hypothetical, and we must be content with the results which may be gathered from wide and general comparisons of phenomena on the grand scale. We shall confine the inquiry to metalliferous veins. Relation to the different kinds of Rocks. Considered as to their chemical nature, rocks may be classed as calcareous, argillaceous, siliceous, and mixed ; as to their mineralo- gical characters, as uniform, or varied, granular, compact, or crys- tallized; as to their origin, aqueous, igneous, or metamorphic. Metalliferous veins occur more or less frequently in every one of these classef of rocks. In limestone, in argillaceous slate and shale, in quartz and sandstone rocks, and in rocks of mingled ingredients ; in uniform slates, and fragmentary millstone grit, in granular sand- stone, compact limestone, and crystallized limestone and granite; in sedimentary grits and shales, in pyrogenous porphyries, basalts, and metamorphic conglomerates. The existence of mineral veins in a rock is therefore wholly independent of the particular chemical and mineralogical nature and proximate origin of that rock ; nor, when due allowance is made for the relative prevalence of the dif- ferent kinds of rocks, does there appear any reason to admit that any preference or more frequent occurrence of metalliferous veins in rocks of particular kinds can be traced, except in particular districts. AFFINITIES OF METALS TO CEETAIN BOCKS. 545 Teins of Certain OTetais. There yet remains the inquiry whether certain metals are specially associated with or related to particular sorts of rocks. In order to answer this question satisfactorily, we must not content ourselves with instances such as tin veins and mercury veins, which occur in so few localities as to be rather de- pendent on their geographical position than on their geological repo- sitories, hut must cite veins of lead and copper, and disseminated ores of iron and manganese. Hardly any substance is more abun- dant in the mineral kingdom than iron pyrites ; it occurs both in veins and disseminated crystals or concretions ; and, in one or other of these states, it is associated with almost every known rock. It occurs disseminated in limestone of various kinds, as primary lime- stone, carboniferous limestone, and chalk ; in clay slates, shales, and clays ; in greenstone, amygdaloid, and basalt. Veins containing iron pyrites traverse rocks of as great diversity. Copper pyrites is not disseminated through so many rocks as iron pyrites, but it occurs in veins which traverse limestone, sandstone, and shale, clay slate, mica schist, granite, &c. Ores of manganese are also very generally diffused through rocks of very different kinds. The converse is true. In one and the same kind of rock occur veins of copper, lead, silver, and tin. Affinities of Metals to Certain Rocks. There are some metalliferous veins which traverse different sorts of rocks, and give us an oppor- tunity of ascertaining whether any differences in the contents of the veins correspond with the variations of the rocks. The tin veins of Cornwall sometimes pass through clay slate and granite ; they pro- duce ores in both. " A vein that has been productive of copper ore in the clay slate, passing into the granite, becomes richer, or, what is more remarkable, furnishes ores of the same metal differently mineralized. If we pursue it farther into the granite, the produce of metal is frequently found to diminish. A change of ground is looked upon by miners as affording reason to expect an alteration for better or worse."* in Silesia. Remarkable instances of this relation are given by Von Dechen.f The numerous veins which cross the steeply inclined strata of greywacke in the Liegen district, ,are metalliferous in narrow bands parallel to the inclined beds of greywacke. The veins of the Kupferberg, in Silesia, bear ore only in the hornblende schist, and are impoverished in mica schist. At Joachimsthal the mica schist is traversed by quartzose porphyry in veins, which, as well as the contiguous rock, hold pyrites in mica slate. The rothegang of Elias consists of loam, and holds only uranite ; where it runs between mica schist, and a porphyry vein, and where it traverses the latter, * Taylor, Report on Veins. t De la Beche's Manual, German Trans., 594. 546 MIKEKAL YEINS. its substance is a red hornstone, and it bears vitreous silver, native silver, arsenical cobalt, bismuth glance, kupfernickel, arsenic, and bismuth ; but red silver, elsewhere abundant, is entirely wanting. in North of JEngiand. In the lead veins of the north of England, which are situated in the carboniferous limestone tract, a singular dependence is observed between the contents of the vein and the nature of the adjacent rock. The vein divides limestones, sandstones, and shales, and these are brought variously into opposition by the dislocations which accompany almost all the veins. The vein is sometimes productive of lead ore under every case of opposition in rocks. Where limestone, or schist, or solid sandstone forms the walls, its productiveness is at the maximum, but generally it is con- tracted in breadth and impoverished in its metallic contents, wherever it is included between walls of shale, and even where only one side is occupied by shale, the same effect is frequently observed. It would appear that the impoverishing influence of the shale is referable to mechanical causes. In the same way as the shales in a coal-pit swell out from the undisturbed parts to fill the artificial vacuities, so we may conceive them to have done into the natural fissure ; this will account for the contraction of the vein. In the process of crystallization, to which all the contents of a vein are subject, it seems conformable to analogy to suppose, that the permanent walls of limestone and gritstone would permit a more early growth of sparry and metallic crystals, than the crumbling edges of shale ; a supposition, perhaps, confirmed by the occasional mixture of shale in the sparry mass of a vein, where it is "nipped," as the miner says, in beds of shale. There may be something in this due to electrical affinities, and we may perhaps apply the same supposition to the cases in Cornwall and Germany, quoted above, where the deposition of the ores is influenced by change of ground. Quantity of ]>ad Ore from Different Beds of Limestone. From some or all of these causes it happens in the north of England that certain limestones are very much more productive than the others ; in different mining districts, different limestones are thus favourably distinguished, but in the country of Aldston Moor, Teesdale, and Swaledale, the uppermost thick limestone is by far the most rich in lead. To prove this, and at the same time to record a valuable fact, we may copy from Mr. J. Taylor's report on mineral veins* the fol- lowing statement of the quantities of lead ore actually extracted from the several sites of bearing beds in Aldston Moor in the year 1822 ; according to the account of Dickenson, we have added the thickness of the several beds. * Reports of the British Association, vol. ii. LEAD OEE. 547 Limestone beds : Great limestone, . Little limestone, . Four fathom limestone, Scar limestone, Fine bottom limestone, Gritstone beds: High slate sill, . Low slate sill, Firestone, . Pattinson's sill, . High coal sill, Low coal sill, Tuft, . Quarry hazel, Nattrass gill hazel, Six fathom hazel, Slaty hazel, Hazel under scar limestone, Thickness in Yards. 21 2 8 10 8 8 7 11 4 4 3 3 10 6 12 4 4 Whole produce of the mines of the manor, 1822, 20-827\Bings of 8 28 7 f cwt. each. 91 90 393 21-688 107 289 262 259 327 154 306 44 21 576 18 2 2-365 24-053 bings. Upon the whole there is no sufficient evidence to show that the local production of metallic substances is in any special manner dependent upon the chemical or mineralogical composition, or the circumstances of the formation of the adjacent rocks, though in some particular, and, indeed, many instances, we observe the aggregation of the substances in the vein to have been decidedly influenced by some peculiar conditions of the including rocks. WaUs'o/a Vein. Alteration of Substance. The walls or cheeks which form the more or less definite boundaries of the vein present several facts worthy of notice. In some instances they are highly indurated, as if in contact with trap rocks (north of England), very often fissured, so as to break parallel to the vein ; in others it seems as if certain sorts of rock (as clay slate, both in Cornwall and Germany) were greatly softened, and even converted to clay, along one or both sides of a vein. Werner mentions the decomposition of felspathic and hornblendic rocks for a fathom from the vein. We have also wit- nessed the fact of limestone, usually a blue or gray crinoidal rock, burnt, as the miners term it, that is, converted to a brown granular crystalline rock. (Teesdale.) Another remarkable effect in the walls is the production of slickenside, so long known in the mines of Derbyshire, which are situated in limestone, and filled with fluoric and barytic spars, and yield lead ; in those of Cornwall, which are in 548 MIKEBAL VEINS. killas, and with a matrix of quartz, and yield copper ; in the magne- sian limestone of Yorkshire, where copper or lead lines the limestone cheeks ; and in the faults of the coal system of Yorkshire, where neither spar nor metallic matters are common. These and many other occurrences of rubhed surfaces along planes of fissures speak a clear language, and prove to the fullest conviction the mechanical move- ment of the sides of the fissure upon one another or upon the con- tained substances. The groovings of the surfaces, thus produced by rubbing, indicate, of course, the line of the movement ; the circum- stance that the polished faces are partially covered by lead ore, cop- per ore, &c., as the nature of the vein is, proves, moreover, that the movement was, in such cases, posterior to the introduction of the whole or a part of the mineral impregnation, so that the same fissure has been, in such cases, the plane of more than one convulsive move- ment. We may, perhaps, eventually draw from examinations of this phenomenon, in connection with and apart from mineral veins, some decisive results as to the time and other circumstances connected with the movements of the masses. How can the geologists of Cornwall doubt the reality of those angular movements which have left such clear evidence as the fine slickensides of some of their veins of fissures ? We think with Von Dechen* that any other than the received explanation adopted above is impossible. Relation to the different Ages of Rocks. This Relation evident. There can be no doubt of the fact that the local occurrence of metallic veins is in a very great degree dependent on the relative antiquity of the rocks in the district. It is in the hypozoic and paleozoic generally, and in the igneous rocks asso- ciated with them, that all the veins in Great Britain are worked. In a few instances veins of small value, producing lead and copper, pass through the magnesian limestone ; but not a single example is known of a true metallic vein in the oolitic, cretaceous, or ter- tiary strata. The connection of metallic veins with the older rocks is not an accidental coincidence, but a constantly recurring pheno- menon ; and the absence of such veins from the newer strata in England cannot be resolved into any circumstances of the geographi- cal position of these strata ; for both around the metalliferous slates of Cumberland and limestones of Derbyshire the new red sand- stone formation is extensively spread in contact, and yet not one lead or copper vein occurs in it. Any one who should confine his attention to the British isles might infer that the causes of the pro- duction of mineral veins had been almost wholly inactive ever since * German Transl. of De la Beche's Manual. MODEEtf YEHS T S WEENEE's THEOET OF. 549 the carboniferous epocli ; and as a general expression this may apply to the continent of Europe, though both in the Pyrenees, and around the central granitic tract of France, metalliferous veins, apparently originating in these rocks, traverse strata of the oolitic and creta- ceous systems. The same Relation obtains in Rock Dikes. It must here be re- marked, that both in Great Britain and throughout Europe rock veins and basaltic dikes are in the same manner abundant in the primary and rare in the secondary and tertiary strata. This is one of many general analogies tending to substantiate the opinion pre- viously advanced upon more specific points of agreement, that rock veins and dikes, and metalliferous veins, form two parallel series of igneous products developed during the same geological periods by the same general causes, acting under different circumstances upon different materials. From all our previous investigations we have been led to the conclusion, that in the earlier geological periods the chemical effects of heat were more conspicuously exerted ; and if to this we join the consideration that all the disruptions by which igneous rocks were put in contact with secondary and tertiary strata must have been experienced by the older strata, from beneath which the disturbing force originated, we shall be able to perceive why the primary are so universally and the secondary and tertiary strata so partially enriched with mineral treasures and diversified by rock dikes. Very Modern Veins. As an example of veins of more recent date, we may quote Yon Dechen's notice of the veins of Joachimsthal. In this case the dikes of basalt and wacke which divide the mica slate are themselves cut through by the mineral veins. These dikes are variously connected with great overlying masses of basalt which break into the brown coal formation. It is therefore evident that the silver, arsenic, and cobalt ores have been thrown into the veins at a later epoch than that of the brown coal tertiary deposit at the foot of the Bohemian Erzgebirge. "Werner appears to have been strongly impressed with the belief, conformable to his general theory, that vein formations might be classed as to their ages by mere examination of their component substances. When veins, even in distant countries, contain the same ores and vein stones, and when these are arranged in the same determinate order, he concludes that they belong to one and the same general formation. Illogical and hazardous generalizations are frequent among practical men, and are too often introduced among the valuable facts recorded as a basis for Werner's theory of veins. A prudent reasoner would scarcely venture to trust an inference for lime upon data which indicate only definite chemical action, even in a limited district ; and it must be with some distrust that we can 550 MINERAL VEINS. admit Werner's eight principal vein formations in the mining field of Freyberg, because he does not state expressly that his inferences concerning their relative antiquity were based on observations of their intersections. The following abstract of the account of these eight systems of veins will show the kind of description which should always be given of mineral veins. Werner's Eight Systems The first and oldest produces abundance of argentiferous lead glance. It consists of coarse granular lead glance with from one and a-half to two and a-half ounces of silver per quintal, common arsenical pyrites, black blende in large grains, common iron and hepatic pyrites, sometimes a little copper pyrites, and a little sparry ironstone. The veinstones are chiefly quartz, sometimes a little brown spar, rarely calc spar. These circum- stances occur most generally in veins ranging from north to south. The second yields lead very rich in silver. It contains lead glance large and small granular ; black blende in small grains ; iron and hepatic pyrites, and a little arsenical pyrites. In addition, dark red silver ore, brittle silver ore, white silver glance, plumose antimony ore. The veinstones chiefly quartz, with much brown spar and often calc spar. The veins range south and south-west. The third yields lead glance with one ounce of silver per quintal, much iron pyrites, a little black blende, and red iron ochre. Vein- stones quartz, sometimes with chlorite mixed and surrounded with clay. Veins range north and south. The fourth yields lead glance with one-fourth to three-fourths of an ounce of silver per quintal, radiated pyrites, and sometimes brown blende. Veinstones heavy spar, fluor spar, a little quartz, and rarely calc spar. Veins range east and west. (To this system Werner boldly refers the veins of Derbyshire, the Harz, and also those of GislofF in Scania !) The fifth consist of native silver, silver glance, and glance cobalt, sometimes with gray copper ore, lead glance rich in silver, fine grained brown blende, and sparry ironstone. Veinstones, heavy spar in a state of disintegration, and fluor spar. It always occurs in the inter- sections of the first and fourth systems. (North and south, and east and west.) It sometimes is found even in the middle of the westerly veins. The sixth contains native arsenic and light red silver ore ; with a little orpiment, copper nickel, glance cobalt, native silver, lead glance, iron pyrites, and sparry ironstone. The veinstones are heavy spar, green fluor spar, calc spar, and a little brown spar. Occurs in the in- tersections of the fourth and fifth systems, or in the middle of veins. The seventh is of red ironstone, with a little iron glance, quartz, and heavy spar. Occurs in the upper parts of veins. IGNEOUS ACTION LOCAL CENTEES OF. 551 The eighth and newest is of copper pyrites, mountain green, mala- chite, and red and brown iron ochre, with a little quartz and fiuor spar. Relation to the Local Centres of Igneous Action. Our investigations lead directly to the inquiry, how far the geo- graphical occurrence of metalliferous veins is connected, as that of rock dikes is known to be, with the eruption of igneous rocks and the movements of fluid masses within the globe? Satisfactory evidence on this subject can be obtained in two ways : first, by comparing metalliferous and non-metalliferous districts of old strata in their geographical relation to igneous rocks and convulsions. Secondly, by comparing the relation to igneous agency of the locally metalliferous newer strata. iu Older Rocks. The older rocks are not by any means universally stored with metalliferous veins any more than with rock dikes. Very large tracts in the slate rocks of Devonshire are nearly devoid of metals, but near the granitic masses of Cornwall they are abundantly supplied with veins. In the vast districts of Wales the slate rocks yield copper and lead chiefly along the western borders of the Prin- cipality, where the local centres and axes of elevation are situated. Amid the Cumbrian lakes, lead and copper veins adjoin the granitic, hypersthenic, and syenitic axes of Carrock, Skiddaw, High Pike, &c. They occur near the porphyries and traps of Helvellyn and Old Man, but the greater portion of the slates, far removed from the foci of disturbance, are devoid of mineral treasures. In Scotland, metallic veins adjoin the granitic nucleus of Strontian. The mining tracts of the Harz, the Erzgebirge, Hungary, Brittany, and other localities are convulsed by disruption and diversified by the intrusion of granitic and porphyritic rocks ; the Ardennes moun- tains, which yield few veins, develop hardly any igneous rocks. The carboniferous limestone tracts of Mendip, Derbyshire, and Flintshire, of Wharfdale, Swaledale, and Aldstone Moor, have been shaken to pieces by many convulsions, and they are very rich in lead, zinc, and calamine ; but the greater part of the Yorkshire and North- umberland limestones, affected by only one or a few general elevations, are poor in metal. in Newer Rocks. The newer rocks are metalliferous only in the vicinity of the foci of their disturbance, as round the central granite of France, near the igneous masses of the Pyrenees and the Alps ; in all which places, the metallic ores are so related to the igneous rocks that they occur only in a narrow zone at the junction of the igneous and the altered stratified rocks.* * Observations of Dufrenoy, Von Buch, &c. 552 MINEEAL VEINS. Conclusions on this Subject. As both these methods of comparison lead to one result, we may venture to adopt it ; and the more readily because, in preceding sections, we have found the geographical situa- tion of mines to be related to the elevation of the ground, and the metalliferous strata often identical with those in which rock veins abound. Nevertheless we must not shut our eyes to some decided differences between the situations of dikes and veins. For instance, the Island of Arran is traversed by hundreds of dikes of basalt, por- phyry, and pitchstone, but metallic veins are almost unknown there ; Aldstone Moor is dissected like a map by veins of lead ore, but very few whin dikes occur there ; on the contrary, in Northumberland and Durham whin dikes abound in the coal tracts where lead is hardly known. It is, besides, too remarkable a thing to be over- looked, that, south of Durham, barely a solitary whin dike or por- phyry dike is known through the metalliferous tracts of Yorkshire, Derbyshire, Somersetshire, and Flintshire. This contrast is the more remarkable in the country about the sources of the Tyne and Tees, because there basalt has been erupted in vast quantity, and at its eastern termination appears related to several dikes of great ex- tent. This mass of basalt is traversed by the veins in the same manner as the limestone is, and we may, perhaps, hazard the specu- lation that under this tract of country lay at one time melted basalt, and at a subsequent time the metallic and mineral combinations which fill the veins. Will it be thought too great a stretch of fancy to attribute this change of the igneous materials erupted in the same tract of country to movements in the internal nucleus of the globe not isochronous with the rotatory velocity of the solid superficial crust ? By such an operation melted masses of different nature might at successive times lie under the same surface area. Electricity of Veins. Mr. FOX'S experiments. The direction of electrical currents at small depths below the surface of the earth is a subject on which theory is at present silent, and which has only recently been pro- posed for observation. The observations of Mr. Fox in the mines of Cornwall, and Devon, and North Wales are still the most important of the kind. Mr. Kenwood has also been engaged in many inquiries on this subject. As far as appears at present, the interest attached to the solution of this question belongs more particularly to elec- trical science, and, perhaps, both chemical and thermal disturbances of equilibrium may be concerned in the effect. These currents may be due to local causes. Mr. Taylor very properly observes,* that by * Reports of the British Association, vol. il, p. 18. ELECTEICITT OF EOX's EXPEKIMENTS. 553 the very act by which we gain access to a vein we lay it open to atmospheric action, and consequently to decomposition. Chemical agency commences, and with it, very naturally, galvanic influences are excited. Veins containing ores little subject to decomposition have, he apprehends, been found to give little or no indication of this nature. Mr. Fox appears to think that the direction and intensity of the currents which pass along the veins may be so related to the posi- tion and quantity of metallic matter, as to give reason to hope for some direct useful application of the results to the art of mining. But the novelty of Mr. Fox's experiments, and the connection of the currents with mineral veins, led some geologists to adopt the very hasty conclusion, that the production of the veins was mainly owing to such currents. It is very probable that electrical currents have really been concerned in the distribution of metallic ores both in veins and rocks, for when is this agency absent from any great chemical phenomena ? But to conclude, without any intermediate steps, because mineral veins are channels for electricity, that they have been produced by electricity, is an inference of the same order as that which would ascribe to electrical currents the construction of the galvanic battery. The art of the miner, founded on long experience, is gradually acquiring the aspect of applied science. To bring it fairly within the circle of inductive philosophy to give it more exact laws, based on a surer classification of phenomena is an object of the highest concernment for humanity. On the command which man has acquired over the various properties of metallic matter has depended much of his civilization and a large part of his power over the forces of nature. If this command may be extended, these forces may be still more completely brought within the direction of the human mind. The way to do this is to carry science into the mines, and bring miners into the class-rooms of the professors of chemistry, geology, mineralogy, and mechanics. Practice will thus become method, and experience be exalted to theory. It is amusing at the present day to find in California and Austra- lia the very same modes of working superficial alluvial and deep-bed deposits for gold which were practised in Grallicia and the Cassiterides for tin in the days of Pliny, and Strabo, and Herodotus,* and per- haps in equally ancient times in those hyperborean regions, those Uralian mountains, which still furnish so much gold to Europe. Probably many great mountain chains, full of quartzose and meta- morphic rocks, yielded gold in the earlier ages of the world ; though none of the rivers washed it away in such abundance as the * Hist. Xat., many notices. 554 MLFTEKAL TEINS. streams of Lydia. Not much of the gold and silver of the ancient world was obtained by mines properly so called, at least in Europe, till the heroic spirit was replaced by great commercial activity. Then the Athenians dug silver ores from Laurion, the Carthaginians obtained it from Spain, the Komans separated it from the lead ores of Derbyshire and the north of England. The peculiar mining cus- toms, not yet extinct in Derbyshire and Cornwall, bear testimony to the high antiquity and foreign source of the art of mining, as estab- lished in these countries ; while throughout the north of England such terms as groove, and sump, and toadstone * betray the later influence of German workmen. Those who desire the prosperity of their country can hardly be indifferent to the success of the great effort now making in London to impart a sound education suited to those who engage in mining pursuits. The College of Practical Science in Jermyn Street offers instruction in all those branches of positive knowledge which a miner should know. It is a miner's college. Probably to make it effective, fully effective, there should be preparatory schools mining schools in Cornwall, in Derbyshire, in Northumberland. Here, probably, in the midst of the works of nature and the works of man, the student should learn to handle the ruder implements of art, and become a skilled workman, before he proceeds to metropolitan class- rooms for the study of the more delicate instruments and processes of science. It is not so easy or so pleasant, after cultivating a taste for refined general knowledge, to learn hard and rough work, as to take the upward course of converting the practical skill of a work- man into the directing power of a philosophic master of mining. * Groove is scarcely altered German for a mine; sump, a shaft below level, is clearly from sitmpfen, a German verb to sink; toadstone, in which the metallic vein is unfruitful, is todtstein^ German for dead or unproductive, rock. VOLCANIC ACTION. 555 CHAPTER XVIII. VOLCANOES AND EAKTHQTJAKES.* The phenomena associated with burning mountains contribute powerfully to the interpretation of the older classes of pyrogenous rocks. Indeed, from the lava currents and cinder hills of to-day, we pass by many easy steps to those which flowed over or were heaped up in the earliest historical times ; from these to others which pre- sented the same aspect of long extinguished fires, to Strabo and Empedocles, which now they offer to Daubeny and Lyell. If there be any general differences between modern volcanic and ancient plutonic effects, it is in part attributable to the circumstance, that the modern phenomena best known to us are such as happened on the land subaerial phenomena while the evidence of the ancient fires is chiefly gathered from subaqueous lava streams and submarine beds of ashes. Much of the modern trachyte, basalt, and other melted rock has been exposed by eruption, and indurated at the sur- face ; much of the ancient granite and greenstone was solidified under the pressure of seas and mountains. As in a former page we spoke of the successive existence, in a state of fusion, of different kinds of plutonic rock under the same region, so now, the diversity of volcanic rocks in different parts of the earth's surface, leads to the conviction that, under different geographical areas, we have separately existing different kinds of melted mineral compounds. Vesuvius pours out augitic compounds ; the peak of Teneriffe delivers sheets of glassy lava ; the old volcanoes of France, the Bhine, and Hungary, yielded granular trachytes ; but none bring up granite to be crystallized at the surface. Dr. Daubeny, uniting in his mind the most comprehensive chemical view which the sub- ject admits, proposes, as a rule frequently observed, that the early granitic compounds are characterized by prevalence of silica which not only unites with alumina and other bases, in treble or double atomic proportions, (forming trisilicates and bisilicates,) but, further, often appears in excess, and remains outstanding in abundance as quartz. On the contrary, free quartz and trisilicates are comparatively rare, not only in the products of modern volcanoes, but also in the pyrogenous rocks of mesozoic eras. Among these silicates of lime * The article Geology, as formerly printed in the Encyclopedia, contained an essay, by Dr. Daubeny, on this interesting subject. The present volume being mainly devoted to British geology, it has been found impossible to give here more than the briefest sketch, with special reference to Plutonic rocks. It is satisfactory to refer the reader, for a full account of volcanoes, to Dr. Daubeny's lately republished, very complete, and valuable volume. 556 VOLCANOES AND EAETHQTJAKES. and magnesia are prevalent ; but among the granitic rocks they are rarely found. May we suggest as deserving of attention the pro- bability that granite appears among the oldest of the igneous family because of the gradual cooling of the internal fluid mass, which, bringing into action the unequal relation to heat of silicates and trisilicates, separated these groups in zones. The former (usually more complicated) mixtures might remain liquid, while the latter (usually less complicated) separated themselves in a solid form. On this supposition, the trisilicated zone, being of less specific gravity, would lie uppermost. It would be first consolidated, and might receive a covering of strata, while the silicated mass remained liquid below. Thus placed in contact with the oldest strata of any given place, it might, on the occurrence of subsidence there, enter again 368 Naples. into fusion, and be pressed into the fissures of those strata. A similar case is well known in Pattison's process for refining lead the silver alloy remains fluid, while the simple lead sinks to the bottom in crystals. And carrying out this idea, the trachytic lava of one active volcano, and the doleritic lava of another, would seem to indicate the stage at which, in those places respectively, the vol- canic process had arrived. In this hypothesis, however, the effect of local subsidence or elevation of the volcanic region must be re- membered, for thus the phenomena might be repeated. Perhaps this has happened in Auvergne. It is only in a few districts that any such marked succession of different volcanic rocks produced in successive times can be recog- nized. Perhaps it is recognized in the Katakekaumene, a district of YOLCANIC ACTION". 557 Asia Minor, rendered classical by the notice taken of it by the geo- grapher Strabo.* Besides the three truncated cones which caught the attention of Strabo, Hamilton t notices about 30 older craters, a still older basaltic plateau of tertiary date, and yet more ancient trachytes. The temperature of the lava at its efflux from a volcano is often registered as that of a red heat, say 1000 F. If derived from the earth's interior heat, we must suppose the liquidity to have been communicated upward from a depth of 8 or 12 miles (950X15 or 20 yards 14,250 or 19,000 yards). The agent of uplifting being by common consent admitted to be gaseous, or the vapour of water, we find that at such a heat the steam power would be equal to balance Guadalonpe. a column of liquid lava three, four, or five miles in height. Volcanic explosions are generally admitted to be the effect of the expansion of an aeriform fluid collected irregularly below the crust of the earth. This fluid has been supposed to be steam, generated by contact of water, heated by the interior masses ;J extricated from spheroidal water by cooling of these masses ; or gas separated from the liquid subterranean ocean, during the cooling and consolidation of it, and accumulated to high pressure above it. In regard to this latter view, the reader should be aware, that some metals combine with * xiii. 4. ii. The description of this treeless tract, with its burnt ashy surface, and its three upswelling craters (T$-I; both in Europe and America. taken generally ........ (. anticlinal axes, vial beds I Anticlinal axes and great) faults of the slate system..) Immense disruptions and j faults of the coal system. . . "i Immense dislocations and) faults of coal strata ........ J Immense dislocations and) faults ..................... f Mountain ridges of zechstein,) &c ........................ r Abrupt and distorted strata} of oolitic system ........... j Abrupt elevations of green} sand and lower chalk ...... f Elevations of chalk and green) sand ...................... f Localities of some of the phenomena. The Hunsdriick and Taunus. Calvados, south-west border of the Vosges. Westphalia, Belgium. Vosges, and Black Forest Tlmringerwald and Bohmer- wald. Mont Pilat, Cevennes (perhaps the Erzgebirge). Mont Viso, Devolny. Pyrenees, Northern Apennines, the Morea. Detached ridges ............ Corsica, Sardinia, Auvergne. Newest tertiaries uplifted Some diluvial beds convulsed The range of the Western Alps, Diablerets, Mont Blanc. The range of the Eastern Alps from the Valais to Austria, Elie de Beaumont's Generalizations. It is to M. Kill' de Beau- mont that we owe the impulse which the study of the periods of geological disturbance has received, and he is the principal autho- rity for the construction of the preceding table. M. de Beaumont 373 E. De Beaumont's System of Elevations. 1 Snowdon. 2 Ballon s, Bocage. 3 Crossfell. 4 Pays Bas. 5 Rhine. 6 S.W. of Brittany. 7 M. Pilas, &c. 8 M. Viso. 9 Pyrenaeo-Apennine. 10 Corsica. . 11 W. Alps. 12 Alps. makes twelve distinct systems of convulsions which are supposed to have happened at as many distinct periods, but we do not find suf- ficient evidence to substantiate the division into five systems, of the first and second of our table. The following is De Beaumont's view of these five systems, including applications in Great Britain for comparison with the details of our first and second groups : DE BEAUMONT'S HYPOTHESIS. 575 Geological period of the Effects noted Localises of some of the convulsions. phenomena. 1. During the deposition" Snowdon, Aaglesea. to upper Silurians. . . ) t Great M* and an,,cl,nalJ old red sandstone . . . 3. After the coal strata) TmmpnQP rHntinn nnrt ( From Derbyshire to Northum- 1 <> Aftpr thP ni fr Q f Q ) ( Vosges and Black Forest, from I SF S -'~ ............ { ass I tersandstem ........ J (_ northern counties. Direction of Convulsive Movements. de Beaumont^ Hypothesis. It is impossible to make many observations concerning faults and other dislocations of the strata, without being strongly impressed by the fact that they commonly follow certain straight lines through a country, everywhere pro- ducing analogous mechanical movements. The length of their courses is often so considerable that one great dislocation defines the physical geography of a district. It has been long known that in mining countries the faults take parallel directions, and sometimes two or more systems of dislocations, crossing in certain angles, were found to be of different antiquity. That dislocations were in some respects to be compared to the effects of earthquakes was also well understood, but no one before De Beaumont appears to have carried his notions of the coincidence between the lines of convulsion and the direction of the great physical features of the globe, so far as to venture on the construction of a general system. This excellent geologist believes that there is a constant dependence between the direction of the dislocation, and the geological epoch of its occur- rence, such that all the dislocations of the same age are parallel to one and the same great circle of the sphere ; and that, in most in- stances, dislocations of different ages are parallel to different great circles which intersect one another at assignable angles. How to be Examined and Tested. It will be readily understood that this general hypothesis is not to be tested by single or small dislocations. It must be examined on a great scale, by means of very exact and numerous data. It is not too much to assert, that in the present state of geology, the facts known are not clear and numerous enough to support this hypothesis ; and on the other hand there are not facts to warrant the unconditional rejection of it. It must be looked upon as a first attempt in a new field, as a gene- ralization carried to extreme ; but it is certainly founded on important data, and in several instances agrees well with observation. The 576 VOLCANOES AND EAETHQTJAKES. principal difficulty of applying satisfactory tests to its consequences, arises from the uncertainty of the exact date of many of the most characteristic convulsions. We cannot positively tell whether the dislocations of the Grampians and Lammermuirs, which take parallel courses, were geologically synchronous or not, because the beds dis- located are not the same. Even in the case of the great faults which followed upon the carboniferous system, the limits of the geological epochs of their occurrence are often too vague for the application of such a theory. Rothetodteliegende and magnesian limestone cover unconformably the coal of the north of England, and thus define the date of the convulsions ; but in the south of England these are of rarer and less regular occurrence, and often entirely wanting, and then the new red sandstone above the coal gives only a vague ap- proximation to geological time. At present these are irremovable difficulties. We can, then, with strict propriety, only examine 7 e ^ the question of the dependence of the direction of dislocations on the geological period, by com- paring together, first, the direc- \ 8 tions of those dislocations which \\ \ are not known to be of different ages ; and second, of those dis- locations which are known to be of different ages. The subjoined diagram (fig. 374) is intended to show the directions of three of the great movements of strata in Britain which appear to be grouped in traceable systems. The earliest in the catalogue is that N.E. and S.W. system which includes Snowdonia and a large tract about it. By this 374 ^ - the Cambrian strata, as under- stood by Sedgwick (including the lower silurian of Murchison), have been much disturbed in North Wales, so that unconformity appears between them and the lower part of the upper silurians. * 374 Three Systems of Subterranean Movement in Britain. 1 Clyde. 6 Nith. 11 Snowdon. 15 South Wales. 19 Highclere. 2 Eden. 7 Ken. 12 Dolgelly. 16 North Devon. 20 Surrey. 3 Kibble. 8 Dee. 13 Bala. 17 Mendip. 21 Sussex. 4 Derbyshire. 9 Clwydd. 14 Dyfi. 18 Wilts. 22 Isle of Wight. 5 Annan. 10 MenaL HOPKINS' S THEOKT OF ELEVATION. 577 Another great system of movement is typified in the north of England by the great faults and anticlinals of the Pennine chain, varying from N.N.W. to S.S.E. Nearly parallel to this are the dales of the Nith and the Annan, the Dee, and the Clwydd. These dislocations precede the whole mesozoic system. A third series of parallel or nearly parallel movements affects the south of Ireland, South Wales, and the south of England. In South Wales, the Mendip hills, and North Devon, it disturbs all the strata earlier than permian ; and in the isles of Purbeck and Wight, and the weald of Sussex, it disturbs all the eocene strata. This appears a case of nearly the same direction, and nearly the same kind of movement (anticlinals and synclinals), affecting a given district in different geological times. The earlier movement was continued both eastward and westward farther than the later one, so as to embrace a length of fully 700 miles of the earth's surface from Bantry Bay to Elberfeld. The later movement, though less ex- tended in length, affected a large breadth of country from the Isle of Wight to beyond the Thames valley. More Limited inquiry. Relinquishing for the present any further attempt to construct a general system of relation between the age and direction of dislocations, we may still find it useful to inquire what laws of direction belong to dislocations in a limited district. Hopkins'* Theory of Elevation. Mr. Hopkins has given a mathe- matical form to the experience of miners and geologists which had recognized the existence in a limited tract of two sets of dislocations often bearing metallic matters of different kinds at right angles to one another. He shows by simple reasoning how these may depend on one system of movement under that district. Suppose, under the whole of a limited tract, an expansive force gradually augmenting, and capable of bearing up the whole mass of the strata there. Let these strata be capable of extension, so that they should swell up into an arch, but let their extensibility be limited, so that at last the arch must break. It will depend mainly on the outline or figure of the ground raised, what shall be the direction of the fractures. If the area be indefinitely very long as compared to the breadth, and the sides be parallel, there will be, in the first place, one or more fractures parallel to the length of the figure across the lines of greatest ex- tension and, secondly, other fractures depending on them, at right angles to them. Thus, in the mining districts of Aldstone moor, the north and south fractures, parallel to the great Pennine fault, and the east and west fractures, at right angles to these, compose a system in accordance with the mechanical theory. Again, if the force under a given district be determined by any peculiarity of the rocks to a conical elevation, there will be radiating primary fissures, and secondary concentric ones. Such a case, perhaps, 2 P 578 VOLCANOES A1S T D EARTHQUAKES. occurs in the volcanic elevation of Mont D'Or.* An elliptical eleva- tion would have characters intermediate between the two, and the same district may show traces of one of these superadded to the narrow rectangular elevation first noticed."]" Such a case occurs in the Weald of Sussex. By cautiously employing this ingenious mode of inter- pretation, we shall be able to determine in any given region where the fractures of the strata are well traced, not only what was the whole area of the ground subject to any movement, at a given time, but what part of that area was moved, by one definite force acting everywhere below it, in a certain characteristic manner. The remarks already made, and in the section on mineral veins, will render it unnecessary here to quote examples in which Mr. Hop- kins' s views find a useful application. We will only state a single case of the parallelism of trap dikes, which has been furnished by Archdeacon Verschoyle, in the north-west part of Mayo and Sligo. He describes no less than eleven basaltic and amygdaloidal dikes, which, in a space of 11^ miles in breadth, traverse the northern part of the district in a nearly east and west direction, and cut through all the formations from the gneiss to the carboniferous limestone. One of these dikes he traced between 60 and 70 miles, and believed it might be followed much farther to the eastward. Two of the dikes are crossed by others having a north and south direction. Direction of the Strata. Mitchell's Views. It was long since remarked by Mitchell, that the direction of the strata in any region was generally parallel to the ranges of mountains ; a truth of great importance in the modern system of geology. The prevalent range of the strata in any country must, however, depend partly upon another circumstance, viz, the original line of the ocean boundary. In many parts of the globe the most prevalent direction of the strata is observed to be north-east and south-west. Humboldt was so struck with these loxodromic lines in Europe, that he says one of his principal inducements to visit equinoctial America was to examine the directions of the strata there. He has furnished evidence that the parallelism of the strata to the great lines of mountains, is a general law of nature. Necker's inferences. M. Necker, in a communication to the Societe (THistoire Naturelle de Geneve, has shown a very unexpected coincidence over large portions of the northern hemisphere, of the direction of the strata, and the curves of equal magnetic intensity, as traced by Colonel Sabine. One of these curves, that of 297 seconds, traverses Scotland in a direction north-east and south-west, which is exactly that of the * Mem. Geologiques, de la France. t Cambr. Phil. Trans., 1837. I Proceedings of the Geol. Soc., 1833. EFFECTS OF CONVULSIONS ON LAND AND WATEE. 579 strata ; it keeps the same direction by Christiania in Norway, where, according to M. Von Buch's observations, the strata trend north-east and south-west, and passes through Sweden, where, according to His- inger, the same direction of strata predominates. On arriving at the gulf of Bothnia the magnetic curve turns north-west and south-east, which, according to Strangways, is the direction of the southern border of the Swedish and Russian granite. The curve of 308 seconds enters Europe by Lisbon, and passes south-west and north-east through the Spanish peninsula, which is nearly the line of most of the long Sierras between the great rivers ; it passes by the Cevennes, and goes parallel to the Alps in their north-east course to the Tyrol, but there turns south-east, as do also the lines of stratification through Carniola, I stria, Croatia, Dalmatia, and the Morea. Parallel to these are the Carpathian mountains. The same correspondence between the magnetic curve and the lines of strata is traced through the Crimea and along the Caucasus. In North America the magnetic curve and the stratification range north-east and south-west along the whole eastern coast; in the Rocky mountains both extend from north north-west to south south- east ; in Mexico the magnetic curve takes the parallel of the Cor- dillera of Anahuac north-west and south-east, and ranges along the south coast of New Spain. Farther to the south the curves resume their course north-east and south-west, which, according to Hum- boldt, is the direction of the strata in Venezuela, and between the Orinoco and the Amazons. The mighty chain of the Himalaya, which in Nepaul bears north-west and south-east, and turns north- east at the north-east extremity of Bengal, is parallel to the curve of 297 seconds which was first noticed. These remarkable accordances deserve the attention of geologists, who must always receive with particular gratification any results tending to connect the general facts of the construction of the crust of the earth with the laws of the distribution of terrestrial magnetism, electricity, and temperature. Effects of Convulsions in altering ilie Relations of Land and Water. The submarine origin of the whole stratified crust of the earth being admitted, and the actual elevation of the rocks above the sea in the existing continents being known, it is required to determine the several geological periods when different parts of the solid land were raised above the waves. It is usually taken for granted that this effect has been produced by the several systems of convulsions which have impressed angular movements upon dislocated portions near the surface of the earth, and thus raised some portions and, perhaps, depressed others. That this general impression is fre- 580 YOLC ANDES AND EARTHQUAKES. quently well founded, though it does not embrace the whole truth, will appear from the simple consideration, that the whole configura- tion of the dry land, whether in islands or continents, is dependent upon the direction and elevation of the chains and groups of moun- tains, which were certainly elevated, at various assignable geological epochs, above the ancient sea. It may be asked how is this ascertained ? The mere fact of those mountains being convulsed, and the strata therein thrown into angular positions, does not seem to prove that the region was ele- vated by such action above the level of the sea, nor, perhaps, that it was uplifted at all ; since it may be imagined, with some theorists, that the neighbouring parts were depressed, and that the general level of the ocean has been lowered. In answer to this we may pro- ceed to show that the effect of the convulsions was relatively to raise the convulsed parts ; that these parts were in several instances ele- vated above the sea at assignable periods ; and that these effects were independent of any imaginary depression of the general level of the ocean. deration the Consequence of Convulsion. That the effect of COn- vulsions has been, generally, to raise the convulsed parts will appear by considering what is the focus of the disturbance and the direction of its energy. The mountain chains and groups are most certainly the foci of the disturbing forces ; for as we pass towards them, from all sides the number and force of the dislocations continually increase, and the declination of the strata grows more and more violent. The direction of the disturbing force is by the same process of observation clearly discovered to be vertical or nearly so, and outwards from the central regions of the earth. It was an expansive force, which employed its principal efforts along certain lines and about certain centres, there breaking and bending the strata in the highest degree, but also lifting them up on all sides around. As far as we can judge, this elevation of the mountain chains and groups was generally unaccompanied by any neighbouring violent depression ; for the inclination of the strata for the most part gradually subsides to a gentle slope, and finally vanishes in nearly horizontal planes. In the mountain chain itself various and suddenly reverted dips may be met with corresponding to the violence of the disruption, but by a careful study of the exterior slopes the general tendency of the con- vulsion may be clearly deciphered. The same data will not, however, by any means give us right to conclude that the mountains so uplifted were raised above the sea, because, though we may know the absolute height of the vertical movement, this will avail us nothing in our ignorance of the original depth of the water. We must examine to see whether they bear on any part of their surface any traces of those later marine deposits OCEAN LEYEL. 581 which spread around their bases. If they do, we may be sure they were not elevated above the sea till after the date of these strata ; as, for instance, the Alps, which bear upon their crests portions of oolitic, cretaceous, and tertiary strata are thus proved to be of mo- dern elevation. If they do not, and the newer marine strata around their bases have been deposited horizontally against the slopes of the mountains, we are entitled to believe that these had been pre- viously reared above the sea. This conclusion, however, it must be always borne in mind, does not inform us correctly to what height they were reared above the sea, but leaves us to infer that they have since partaken of another movement by which these newer strata have been placed at their present elevation. Speculations ou the Ocean Level. The facility of escape from many embarrassing considerations which a general depression of the level of the ocean seemed to offer was too tempting to speculators in geo- logy to permit them to inquire into its physical probability. The simple question of what has become of the vanished water was disre- garded by Werner, and perhaps never thought of by his followers. It will not now be sufficient to press it into a subterranean abyss, nor to carry it off to other planetary regions in the tail of a comet. We must admit that the quantity of water upon the globe has been constant, or give up all pretence to philosophical moderation ; and with this restriction upon our inquiries it becomes easy to prove that the level of the ocean is confined within very narrow limits of fluc- tuation, so long as the earth's axis and rotatory velocity are sup- posed invariable. If the level of the ocean be expressed either by taking its mean depth, or the mean radius of its surface, this level may be supposed variable by reason of any local convulsive move- ments of the dry land or bed of the sea, any change of dimensions of the whole globe, or any alteration of the mean temperature of the water. First of temperature. If we take the mean temperature of the ocean at the equator 81*5 F., its temperature at the poles OO F. on the surface, and at some depth (d) 81*5 F. ; and suppose, in con- formity with some hypotheses from organic remains, that the whole surface of the globe was formerly subject to a temperature equal to that of the equator ; the ocean at that period must have been defined by a longer radius. Variable with Change of Temperature. The expansion of the polar waters, supposing them to have been fresh, would be at the surface only to the extent of 4'0, because at temperature 0'0 F. fresh water occupies nearly the same space as at 77'5 ; at nearly half the depth (d) it would expand through 42' 75, at the depth (d) nothing. Average expansion 22*4, which corresponds to of the depth.* * Fresh water expands about ^V for 1SO - 582 VOLCANOES AND EABTHQTJAKFS. If we suppose d to be 10,000 feet, the polar expansion = 54 feet. But if we suppose the water to have been salt, the expansion at the polar surface, from 0'0 F. to 81'5 F. 81-5 x l 8W 1th* 180 20 3600 44 of the depth and at other latitudes = X sine lat. At the depth (d) nothing. The average expansion 44 would therefore be p = 114 feet = 228 feet. 88 It is evident that such fluctuations of level, however real, are not adequate to explain the desiccation of large tracts of land. What might be the effect of a general change of dimensions of the globe, through variation of its own temperature, is beyond our power of investigation, because we do not know in what ratio the solid and liquid parts of the globe would alter their dimensions.f We may, however, consider the effect of a general change of dimension of the nucleus of the globe, supposing the superficial temperature unaltered. According to all analogy of organic forms, the globe may be supposed to have grown cooler continually, and thus to have contracted in bulk ; but this, by shortening the mean radius, would cause the ocean level to rise upon the land, which is contrary to the effect we wish to explain. If we even allow, for the sake of argument, an augmenting diameter to the globe, this must go to a very great amount before the level of the ocean, as compared to the land, would be sensibly affected. If the ocean be 5 miles deep, the diameter of the earth must be augmented \\ mile to cause the level of the water to sink relatively 10 feet, and to sink it half a mile the radius of the ocean must augment 400 miles. It is unneces- sary to prosecute this inquiry, for a sinking of half a mile would be insufficient for the desiccation of the whole dry land, even allowing the great mountains to have been uplifted. Variable through Intestine Movements. The most interesting part of the inquiry remains to be more carefully examined the variability of the ocean level in consequence of displacements of the solid land. We shall put the case in three forms, and according to each of these imagine the present continents to be depressed beneath the waters of the ocean, as they once certainly were. First. We may suppose no vacuum to exist below the crust of the earth, nor any receptacle occupied by air or gases into which the * Salt water expands about ^ for 180. t Since this section was written, Mr. Babbage has made known some interesting views bearing on this subject (Proceedings of the Geol. Soc., 1834), and Mr. Hopkins has attacked the problem of the earth's internal fluidity. OCEAN LEVEL VARIATION OF THE. 583 solid land could sink, but that a sinking in one place should be com- pensated by a rising in another, so that the cubic dimensions of the globe should remain unchanged. Moreover, to put the case to extreme, it may be a condition that the land shall sink so that water shall cover the whole surface. In this case the level of the ocean would rise, that is, the mean radius of its curved surface would be lengthened, by a quantity depending on the mass of the solid land submersed, and on the relative area of land and water. This relation of area is more than 3 water to 1 land. The cubic content of the solid land may be thus estimated. In England, Wales, and Scotland, the average height of those conspicuous mountain masses which appear to give shape to the whole country is about 3,000 feet ; and if we consider this as the apex of a cone whose base is the whole area, we shall have the mean height of the land above the sea 3000 = feet. The mountain masses, however, do not really affect, 3 by their special elevation, more than a fraction of the area of the British Isles ; the far greater part of the land depends on heights not exceeding 1,000 feet. If the mountain tracts be called ^ of the area, and the hilly and more depressed parts i, we shall find the mean height of the whole mass of land ( 8QO + 1QQQV \ = 66 6 feet. But on account of the valleys which divide the principal masses, we may reduce this say to 500 feet. This principle applied to the continents of Asia and America would give in round numbers about 2,000 feet mean altitude of land ; and as the area of the expanded ocean would be four times as great as the land is now, the total mean elevation of the water, by the submersion of the whole mass of land, would be about 500 feet ; a quantity too small to be of use in explaining any but the lesser order of geological phenomena, and which may be considered as the extreme limit of oceanic rise. Secondly. We may suppose the existence of cavities into which the solid land might sink, so that there may be no elevation in another place corresponding to the given depression. To put this also to extreme, we may imagine the very improbable case that a mass of solid materials equal in bulk to all the solid land above the water, should sink into a cavity, and that the surface of the sub- merged land should be level. The level of the ocean would be nearly unaltered, except in a small degree, by reason of its shallow expansion over the area of the land. We might go on to suppose even the enormously improbable case of cavities existing so large as to admit twice the whole solid mass of the continents, and that these should 584 YOLCANOES AND EAETHQUAKES. sink with an equal bulk of materials into these cavities. Even in this case the ocean level would only be lowered 500 feet. Thirdly. If we suppose contemporaneous or successive elevations and depressions, however extensive, the ocean level would osciUate about a constant line. Conclusion Adopted. It is evident, therefore, that by no stretch of conjecture, that is not absolutely monstrous, can we torture the known laws of terrestrial arrangements into agreement with the hypothesis of any but small changes of the level of the ocean ; a con- clusion of the highest value, since it enables us to argue upon that level as a general standard to which we may refer all the effects of internal movements, in whatever period, and by whatever forces produced. It must be remarked, however, that it fixes no limits to the effects of the temporary violence induced in the ocean by such movements, because these effects would be proportioned to the impulse with which they were attended. Gradual iteration of i.nini. It appears that we cannot in all cases understand the possibility of the elevation of land out of the sea by the mere effect of local convulsive movements, but must in addition admit the gradual rise of large tracts of land whether convulsed or not at some earlier epoch. England is an unexceptionable example ; and probably every country will be found to require the same admis- sion. The necessity for admitting this gradual elevation of the whole country, is first suggested by the difficulty of otherwise accounting for the altitude of the tertiary and other marine strata, which have been deposited long since the great convulsions which partially or completely raised the primary and other old systems of rocks, and are, in general, remarkably free from the traces of any such events. The older geologists relieved themselves from this dilemma, by in- venting the gradual diminution of the level of the ocean ; the moderns meet the difficulty by supposing a gradual intumescence of the land. The former mode has been proved to be incredible, the latter we certainly do not yet understand, but it is not at variance with the established facts of convulsive elevation. Where convulsive movements can be traced in their effects we have a good local cause for the local elevation of the ancient bed of the sea ; but where no such movements can be traced, and yet the land is raised far above the sea, it is clear that we must neither admit convulsion, nor deny the relative change of level of land and water. Now the areas of country which are elevated, but not convulsed, in such a way as to account for this elevation, are very extensive. The greatest portion of the level regions of the globe is thus circumstanced. In many instances we might plausibly explain the facts by supposing that the same localities (as mountain chains and groups) which had been in very ancient periods liable to great convulsive movement, STJBTERBANEAN EXPANSION. 585 were during later periods influenced by more gradual and continual subterranean expansion, so as to bear up on their slopes the newer strata formed and in process of formation. This would apply to England, whose great centres of old convulsions are nearly confined to the western borders, and it seems equally suitable to most coun- tries whose lines of mountains correspond with the general figure. The principle, once admitted however, will be found applicable to all situations, and equal to solve a very difficult class of problems in geology. It may even clear our way through the cases of alternate elevation and depression, such as the temple of Serapis on the Nea- politan shore : for whatever be the cause of local intumescence, it may be discontinuous or intermittent, and elevation in one quarter may be counterbalanced by depression in another. Proposal of a Hypothesis on the Subject. But is such an assump- tion of local subterranean expansion consistent with what is known of the interior constitution of the globe, or is it a vain speculation ? So little is known of the interior of the globe, that almost any hypo- thesis is safe from coming into collision with that knowledge, pro- vided it allows of given mean density, and a specific gravity increasing toward the centre. Newton supposed the spheroid to be homoge- neous ; it has been found that this supposition is by no means fitted to fulfil the observed conditions of the problem of the earth's figure; and the irregularities of attraction indicated by the pendulum ex- periments, and of curvature by direct meridional measures, seem to show that the concentric masses of the spheroid are not of uniform density. This being allowed, there would seem no objection to suppose that the densities along any one radius of the spheroid are variable, by reason of intestine movements among the unequally dense parts of the concentric masses, and this would exactly answer the conditions of the geological problem. For the length of any radius of the heterogeneous spheroid would necessarily vary with the densities ; and considering the small proportion of the height of the land above the mean radius of the latitude, it is clear that small internal changes in a length of 4,000 miles would easily account for variations on that line to the extent of 1,000 feet or yards. This hypothesis would give a gradual and prolonged elevation in some parts and corresponding depressions in others ; it would not affect in a sensible degree the astronomical elements of the planet, but would change more or less completely its hydrographical boun- daries. It appears consistent with the inference to which we were conducted while studying the phenomena of mineral veins (p. 552), viz. that under the same region of stratified rocks different sorts of igneous rocks had been at different times developed, and is suggested again by the successive consolidation of trisilicated and silicated 586 VOLCANOES AND EARTHQUAKES. minerals, (p. 500) ; and at all events may be used as a first contri- bution towards a sound mathematical theory of general subterranean movements independent of volcanic convulsions. How Possible. To reconcile this view of the variation of density under given tracts of the earth's surface, with the inferences which have been already presented concerning the interior constitution of the earth, is not difficult. We have only to remember that, in the course of the consolidation of the crust, the silica and trisilicates of granite, &c., first solidified, have a specific gravity of about 2*6, while the silicates, remaining liquid at the same temperature, have a spe- cific gravity of about 3' 2 and more. Now let the solidification of the first group have proceeded so far under a given country, as to form, partly by cooling, and partly by pressure, those partitions which enclose the liquid bases of volcanoes. If this solidification proceeded only to the depth of thirty- two miles, we should have the specific gravity on the lines or over the areas of this crystallization diminished, and that of the liquid parts augmented, so that the solid part ought, as compared with the average, to have a tendency to rise, and the liquid part sink, until the columns had the relative height of 26 and 32 miles. This is to take the extreme case ; but diminish the calculated difference as we please, it is obviously a true and effective process of nature, capable of giving long periods of elevation to some tracts and of depression to others, and of calling up very powerful internal pressures without convulsion. Again, if over the parts remaining liquid, gaseous pressure should be generated by any of the processes already suggested, the depres- sion of the area might be arrested, and even reversed ; and the re- lease of this pressure might again ca^se a return of the depression. Other variations may be easily imagined, and upon the whole this hypothesis, which was proposed in the former edition of this treatise, appears to us to have only gained strength and generality, in consequence of subsequent discoveries. Relations of Land and Water. We may now attempt a brief sketch of the relations of land and water in particular regions, during the successive geological periods, and notice the character of the agencies concerned in producing them. It is sufficiently evident that we are precluded from any attempt to assign these relations generally, because we cannot know what tracts of land were once raised above the sea, and have since been submersed. This applies with great force to the periods, whatever they were, which preceded the formation of what we call paleozoic strata ; for concerning the question of the existence of land during those periods we cannot even offer a conjecture, except upon the basis of inquiries into the remains of terrestrial organic forms em- bedded in these strata. The evidence which they afford negatives, EELATION OF LAND AND WATEE. 587 as far as it goes, the existence of land plants ; but it is chiefly by the great extent and uniformity of character of these deposits, and by the absence from them in the lower parts of marks of littoral or fluviatile action, that geologists might justify a belief that little or no dry land divided the wide primeval ocean. We pass to consider the state of things during the palseozoic period. During the Palaeozoic Period. It is admitted that the greatest effects of the elementary movements which can be traced in the existing ranges of mountains were posterior to the lower palseozoic deposits ; but there are good grounds for believing that dry land in some (unknown) situations began to furnish vegetable reliquiae, during, at least, the later part of the period occupied in the deposi- tion of the silurian system. First, there is the certainty that some disturbing effects of igneous agency are traceable among very old members of this vast group of rocks. Secondly, the existence of car- bonaceous matter (anthracite) among them. Thirdly, in the upper- most part of the series occur land plants. At the Commencement of the Carboniferous Epoch. It is highly interesting to observe the harmony of two classes of results bearing on the relation of land and water at this epoch. Some of the most extensive and important physical features on the western side of the basin of Europe have resulted from convulsions preceding this epoch, which certainly raised out of the sea many remarkable ranges of high ground ; and the most considerable accumulations of land plants which have furnished the substance of coal in Europe and North America, followed after an interval those convulsions. It may, per- haps, eventually be possible to derive, from the comparison of the local centres of elevation with the limited fields of coal, some con- clusions as to the physical geography and other circumstances of the place of growth of the vegetables ; at present we shall only ven- ture three remarks. 1. The deposit of coal plants does not in gen- eral follow immediately, but after some interval, the uplifting of certain tracts of land ; for between the uplifted primaries and the phytiferous secondaries, great thicknesses of conglomerates holding few or no plants, and beds of limestone full of marine shells inter- vene. 2. The plants which most predominate in the older parts of the carboniferous deposits in Great Britain (coniferse) appear like the vegetation of a mountain district in a warm climate, while those which abound in the younger deposits of the same period (cactiacea?, equisetacese, &c.) may be more successfully compared to plants of plains and marshes. 3. The coal basins appear related in position to the ranges of primaries uplifted before the deposition of coal, and not to those of subsequent ages. This is an important fact, and must be further developed. On geological maps of the British Isles, the local relation of the lower palseozoic and carboniferous strata may 588 YOLCANOES AND EARTHQUAKES. be seen, and the latter will be observed to form a broad belt parallel to the general course, entering into the indentations, and surround- ing the insulated eminences of the former. But along the ranges of the Alps and Pyrenees, no such bands of carboniferous rocks occur. The British primaries were uplifted before the carboniferous period, the great European ranges after. Coal is, however, not uniformly spread over all the area of the carboniferous rocks. It occurs in the great valleys of the Forth and Clyde, between the Grampian and Lammermuir ranges, in valleys of the Lammermuir ; (Sanquhar ;) round the Cumbrian mountains ; round the Welsh mountains ; in hollows of the Anglesea primaries. Besides these remarkable juxta- positions, the long range of the great northern coal fields is still partially united with the coal deposits encircling the Cumbrian and Welsh mountains ; and it is only by the effect of immense subse- quent convulsions, and the consequent unconformity of the triassic formation, that it does not appear completely united with them. The immense coal deposits of Ireland are in the same way sur- rounded by primary strata, which were raised above the sea before the accumulation of the coal. Parallel to the Hundsriick and to the Taunus and Ardennes, which were elevated about the same early period, lie the coal deposits of Saarbruck, the Netherlands, and Westphalia. Comparing this statement with the inferences con- cerning the growth of the plants of the carboniferous period, and with the peculiarities of the several coal fields, we seem to find a fair basis for reasoning concerning the original habits of fossil plants, which may eventually lead to important results. Before the Saiiferous Epoch. The elevatory movements conse- quent upon the deposition of coal appear to have been very general and extensive, and in the basin of Europe to have materially con- tracted and altered the boundaries of the sea. In England especially this effect is clearly shown by the rising above the sea of the large tract reaching from the Tweed to the Trent, and including nearly the whole of the space between Berwick, Carlisle, Liverpool, and Nottingham ; thus forming a large and nearly united tract from the Pentland Frith to Cheshire. To the same periods we must refer a large augmentation of the previously elevated regions of Wales. It will thus appear that nearly all the northern and western parts of the island of Great Britain were then raised above the sea, which still flowed over the sites of all the midland, eastern, and southern counties. The greater part of Ireland had also emerged. Besides these greater elevations some smaller tracts, which now appear as detached groups of mountains, were then conspicuous as islands. Charnwood forest, the Dudley district, and Men dip are examples. The Cumbrian mountains were half surrounded by a sinuous arm of the sea, which washed the feet of the Pennine chain from Kirkby KELATION OF LAND AND WATER. 589 Stephen to Brampton, expanded into the southern counties of Scot- land, and perhaps connected itself along what is now a part of the Irish Sea, with a great diversified gulf in Cheshire, Warwickshire, Leicestershire. To the east of a line drawn from Newcastle through Nottingham to Exeter, we may suppose it to have been all an open sea as far as the Ardennes and the Harz. It thus appears that some of the marking features of British and European physical geography are of very high antiquity ; and however modified in detail, by sub- sequent internal movements and superficial wasting, their larger proportions and general effect in those early periods may be very well judged of from the characters which they retain at present. It might appear that, during the saliferous period, the elevated lands nourished no great profusion of vegetables ; for throughout the whole of Great Britain the magnesian limestone and new red sandstone system is wholly, or very nearly so, devoid of such re- mains ; and though in a few places in Germany plants are found in some parts of this system, they rather confirm than oppose the general inference. It does not seem possible to trace any close dependence of the local character of the saliferous system upon the circumstances of the physical geography of the regions ; for, correctly speaking, there is very little of local character, except what is imparted by the unequal extension of the limestone groups ; and these are probably wholly derived from marine decompositions. Along the Vosges mountains, perhaps, a peculiar sandstone conglomerate may have been derived from these mountains. Scarcely anything in geology is more remarkable than the great uniformity of appearance of such extensive deposits as those of the saliferous system, with such few remains either of marine or of ter- restrial reliquiaB. The prevalent red colour of this system is of itself a circumstance of great interest, though of unknown origin. In many cases this colour is derived from a superficial coating of oxide of iron round the internally clear quartz grains ; and there can be no doubt that chemical agencies were then in operation of a very extensive and very remarkable kind. It is difficult to avoid believing that the life of the marine mollusca and radiaria was much controlled by these agencies. Before the Oolitic Epoch. The deposits between the coal system and the tertiaries succeed one another so regularly in England, and even throughout Europe, that to explain the successive parallel out- crops of the several strata an obvious supposition is a gradual eleva- tion of the pre-existing land, or a gradual retreat of the ocean. This problem becomes, however, still more intricate when we add the following general truths: 1. That in England the oolitic strata, which succeed the red marls, form hills of greater height than any 590 VOLCANOES A^ T D EARTHQUAKE S. one point of the saliferous formation. The same is true for Germany and France. 2. That there exist beyond the general range of the oolitic outcrops many far detached hills of these strata resting on and overlooking broad plains of red marl, which seem to be in an undisturbed position. It is obvious in these instances that the sur- face has been subjected to enormous waste by the violence of watery currents. In every theory of diluvial or alluvial action it is supposed that these denudations were performed upon the previously dried and elevated land; but few speculators have had the boldness to attempt the solution of the difficulty, by assuming that the inversion of relative level between the red sandstone and the oolitic systems is wholly due to the wasting action of water. Perhaps we shall best consult the true interests of the science by not insisting much upon any mode of accounting for these yet insuf- ficiently examined questions ; but it seems right to observe, that gradual elevation on the west and depression on the east of the south-eastern parts of England, parallel to the line of the oolites, and prolonged in duration through the whole period of the salife- rous, oolitic, cretaceous, and tertiary rocks, would fully agree with the general physical features of the surface of the district, the mi- nuter inequalities of which may certainly be ascribed to superficial watery action. This view appears to agree well with the general character of the upper saliferous, oolitic, and cretaceous deposits, which exhibit many repetitions of analogous rocks and fossils, many deposits of limestone and clay, such as might be formed in quiet or deep waters, with but few beds of sandstone. From some of these local sandstones we learn the fact, that some parts of the land which bordered the oolitiferous sea, nourished a variety of plants, charac- terized upon the whole by a predominance of vascular cryptogamia and coniferous phanerogamia, different from those of the older coal tracts. Effects of Convulsions on the Deposition of Strata and on Organic Life. The formation of extensive conglomerates has been already shown to be a natural consequence of convulsive movements ; and it is in some cases very probable that the disturbance was centered in the immediate vicinity of these accumulations. But it would be a gra- tuitous contraction of a very interesting field of research to limit our inquiries into the effects produced by subterranean movements on the deposition of strata, if we did not take into consideration the peculiarities of mineral character belonging to the several systems of marine deposits, the alternations of marine and fresh water rocks, and the succession of races of organic beings. What dependence SYSTEMS OF STEATA MINEEAL CHAEACTEES OF. 591 there may be between these phenomena on the one hand, and sub- terranean movements on the other, will undoubtedly be revealed by the progress of inductive geology, and results of a very interesting kind will flow from such a discovery. At present, we can only sketch a dim outline of a subject as yet scarcely emerging from ob- scurity. Mineral Characters of the Systems of Strata. Actual Process of Nature Sedimentary deposits, whether they are occasioned by the action of streams and floods from the land, or of tides and currents in the ocean, have a mineral character depending on the nature of the materials acted upon. The same great stream may, according as its different feeders predominate in their action, deposit materials of different quality ; there may be in such deposits effects depending on the season of the year, but all such differences are periodical, and a series of alternations of given mineral aggre- gates is the result. The action of the tides in a certain direction, is also liable to pe- riodical variations of intensity ; the coasts worn by tides may be unequally affected at different times, and the accessions of materials from the land may be irregular ; still these minute inequalities are almost wholly lost when we contemplate the average results of a long-continued course of the same tidal action. Deep-sea currents, so long as they follow the same channels, can hardly be supposed to produce any but very uniform admixtures of sedimentary ingredients. When, therefore, we find a series of sedimentary strata to consist of repetitions of the same materials, or of recurring alternations of different materials, the whole is reasonably referred to a series of the same, or similarly alternating effects of watery action upon the same tract of land, the same line of coasts, or the same channels of the sea. On the contrary, the suppression of one class of deposits, and the production of another, clearly marks out to us that the water has ceased its action on the land, coast, or ocean bed, which it formerly wasted, and transferred its attacks to a new quarter. It was not the perception of these simple laws of modern nature but a clear recognition of their effects in older periods, that led geologists to agree in classing together portions of the innumerable layers or strata into certain groups or formations, according as they are identical or analogous in their nature, very gradually change from one to another, or consist of a series of recurring mineral terms ; and in dividing these groups at the points where new terms appear and old ones are suppressed. Thus the suppression of red 592 YOLCANOES AND EARTHQUAKES. marl, and the introduction of blue clays, marks the boundary of the saliferous and oolitic formations ; the suppression of oolite, and the introduction of green sands, marks the limit of the oolitic and cre- taceous formations. No Universal Strata. Whatever view we adopt of the origin of sedimentary rocks, there can be no doubt that, even from the earliest geological period, the bed of the sea must have been composed in different regions of different materials ; this must have been the case, even if we carry back our thoughts to that remote epoch where we may suppose that nothing solid existed at the surface of the globe, except the products of heat ; for these, in fact, contain nearly all the varieties of minerals, and nearly all the elements of the composition of stratified rocks. The very earliest formations which we have yet succeeded in tracing, exhibit themselves in two very distinguishable masses ; the gneiss and mica schist system on the one hand, and the clay slate system on the other. When, by the partial elevation of these rocks above the level of the sea, the ocean was divided into separate parts, local differences of the sedi- mentary, and even chemical deposits, must speedily have resulted ; and as the extent of land increased in any particular region of the globe, the deposits in the residuary seas thereabout must neces- sarily have become more and more dissociated from those of other regions. It is, therefore, very evident that there can be no universal strata ; that during the greater part of the geological periods, rocks of very different nature may, and, indeed, must have been contempora- neously deposited ; although, according to the circumstance of the cases, the peculiar products of one region may have been, by oceanic currents or other causes, mixed with those of another, and so a con- tinual or interrupted analogy between the series of strata in each maintained. Changing Sediments Connected with Subterranean Movements. We have now arrived at the point when the co-ordination of the diversity of sedimentary aggregates in a given oceanic basin with subterranean movements, and the dependence of the former on the latter, may be presented in the form of a very probable inference. Geologists have long been accustomed, while reasoning on the phe- nomena of tertiary rocks, to recognize the principle of the dependence of the local difference between contemporaneous strata in different basins upon the physical structure of the region from which the ma- terials of these strata were derived. It has been already shown that the successive diversity of strata in the same basin can only be un- derstood by admitting that the different sediments were brought from different regions ; it is evident that for this end the drainage of the land, the flow of the tide, or the direction of oceanic currents, CHANGES OF LIFE. 593 must have been changed ; this can only be ascribed to an alteration in the local relations of land and water, that is to say, to subter- ranean movements. When this change of the sedimentary deposits is sudden and complete, we may generally feel assured that it is owing to violent subterranean movements, which have opened a new communication with the basin: the exact site of the centre of convulsion may perhaps not be ascertainable, though in some particular instances the direction of the new currents may be inferred, and thence their local origin conjectured. When the changes of sediment are gra- dual or alternate, we must apply corresponding inferences with greater caution. In some cases slight movements might accomplish great changes in the nature of the deposits. The map of the terraqueous globe shows us how easily, at particular places, the waters of different oceanic alvei might be brought into union by the lowering of an isthmus or the opening of a strait. If the Mediterranean were con- nected through the Red Sea with the Indian Ocean, would not the deposits in each of them be reciprocally influenced ? Such internal movements as might occasion this appear trifling, when compared to the disturbances which we know to have been many times effected within the range of geological chronology. Successive Eaces of Marine Animals. Change of Organic Races. If, in consequence of internal movements, a given basin were opened to the reception of currents and sediment from a new quarter of the ocean, it could scarcely hap- pen otherwise than that a change should arise in the inhabitants of that basin, by the extinction of some arid the introduction of other species. Scarcely excepting even the earliest series of fossiliferous deposits, there is nothing in geology to indicate that the distribution of species over the globe was regulated by different laws from those which now prevail. The superficial temperature of the globe was perhaps more equable ; and for this reason organic forms might be more extensively distributed ; there might be less local distinction than at present ; but yet each species had its definite boundaries, and different regions were characterized by peculiar races. Upon the establishment of a communication from one such region to another, there must necessarily be a transference of organic life, at least in one direction, according to the locomotive habits of the creatures, and the influence of currents upon them and their ova, and other circumstances. It was with this in view that the passage (p. 71), relating to 2Q 594 VOLCANOES AND EAETHQITAKES. the succession of races, corresponding to successive deposits, on a eriven part of the ocean beds, was written. How remarkable is the coincidence of great convulsions, decided changes of mineral aggregations, and substitution of new organic remains, needs only to be mentioned; for these three orders of effects are all combined in modern geology to characterize the groups or systems of stratified rocks. Fresh Water and Marine Alternations. Few geological phenomena declare more plainly their dependence upon ancient convulsions than the alternations in a given basin of strata, of fresh water and marine deposits. Not that in every case where we see fluviatile or even lacustrine shells alternating with marine exuviae, we must suppose the levels of land and sea to have been changed, because at the mouths of some rivers this might hap- pen from the bursting of a lake, a violent inundation, or even the natural course of things ; but when, as in the coal field of Yorkshire, over the marine deposits lies a great mass of matter derived from the land, and in this a particular layer of marine exuviae ; when, as in the Weald of Sussex, we observe above the marine deposits of the oolites a great thickness of fluviatile deposits covered by marine green sands ; or, as in the Isle of Wight and the basin of Paris, see really lacustrine marls and limestones interposed among really marine strata ; the conclusion seems inevitable that these are effects of changes in the relative level of land and sea. It would, however, be too much to assert in every case that the internal movements were centred near the places where we witness some of the effects. On the contrary, we may perhaps probably often be merely looking upon the consequences of convulsions which happened at great dis- tances of space, and which produced near then* centres of action wholly different phenomena. This mode of interpretation applies very well to those instances in which repeated alternations of marine and fresh water productions occur without any indications of cor- responding local disturbances. As an example, we may cite the marino-lacustrine formations of the Isle of Wight. The Weald of Sussex. Application to a Case proposed by I^yell. One very obvious effect of convulsive movements, whether sudden or gradual, must always be a more rapid rate of waste, both in the land and along the coasts, than usual. It will, no doubt, be possible hereafter to draw from the varying rate of sedimentary aggregation in a given basin some important evidence concerning the amount and duration of the in- WEALDEN BOCKS ELEVATION OF. 595 ternal movements which caused a more than ordinary accumulation of materials in the sea. By combining with this the results of an inquiry into the local site of the convulsion, as inferred from the direction of new sediments, we may eventually he able to point out, with more or less probabi- lity, the original sites of these materials, and thus show how in ancient periods the wasting of one given tract of elevated rocks has contributed materials for the accumulation of new deposits in the sea. So long as, in the prosecution of this research, we confine our- selves to the methods of the inductive philosophy, our progress will be real, though slow. New circumstances will arise to quicken the process and solidify the results, and light will gradually break in upon the yet obscure problem of the physical geography of early geological periods. LyelTs persevering investigations into the history of the tertiary strata have produced a very remarkable attempt to determine the local origin of the materials of the English tertiaries, and the local seat of the corresponding subterranean disturbances , The geographical relation of the anticlinal axis of Sussex and Hampshire to the tertiary deposits on either slope, has long fixed the attention of geologists. It was proved by Dr. Buckland, that the tertiary basins of Hampshire and London were once, at least, par- tially connected. It was known that the first deposits above the chalk were such as to indicate prolonged action of agitated waters, that the subterranean surface of the chalk was uneven, and that among the tertiary deposits were abundance of pebbles apparently derived from water-rolled chalk flints. Lyell supposes that "the chalk of the south-east of England, together with many subjacent rocks, may have remained undisturbed till after the commencement of the tertiary period. When at length the chalk was upheaved and exposed to the action of the waves and currents, it was rent and shattered, so that the subjacent secondary strata were exposed at the same time to denudation. The waste of these rocks, composed chiefly of sandstone and clay, supplied mate- rials for the tertiary sands and clays, while the chalk was the source of the flinty shingle and of the calcareous matter which we find intermixed with the London clay. The tracts now separating the basins of London and Hampshire were those which were first ele- vated, and which contributed by their gradual decay to the produc- tion of the newer strata. These last were accumulated in deep submarine hollows, formed probably by the subsidence of certain parts of the chalk, which sank while the adjoining tracts were rising." * * Principles of Geology, voL iii., 1st edition. 596 VOLCANOES AND EARTHQUAKES. Without following the range of ingenious arguments employed in fortifying his hypothesis, we shall notice the facts which seem most clear in their evidence, and which can be interpreted without theoretical assumptions. Circumstances Favourable to I^yell's Tiew. 1. It is certain that the "Wealden country, with some other tracts in the south of Eng- land, has been uplifted by subterranean movements, independent of that general rise of the whole of the eastern part of the island before adverted to (p. 584). Whether this was accomplished by one or many successive movements cannot be decided by direct evi- dence ; it would appear, however, that the convulsion was not ended till after the deposition of the whole eocene tertiary series. 2. It is undoubted that the upper secondary strata disclosed in the Weald once extended much farther towards the central axis, and have been exposed to enormous waste and denudation. There is nothing to negative the opinion adopted by many geologists, that the whole of the area enclosed between the north and south Downs was once completely covered over by the chalk and the subjacent green sand system ; but this admission is not really necessary to the hypothesis. 3. The tertiary basins on the northern and southern sides of the axis of elevation of the Weald, contain nearly the same kinds of sedimentary deposits in the same order of succession, so that both of them must certainly have been influenced by the mechanical agency of water, flowing under nearly the same conditions, from the same physical region, or from regions consisting of the same mate- rials equally exposed to aqueous erosion. 4. The materials of the tertiary strata, in the basins of London and Hampshire, are analogous to those which have been removed by denudation of the Weald ; since they consist of various coloured sands, which may be imagined to be derived from the green sands and Hastings sands, and of clays which may be supposed to have been furnished by the Grault and Weald clays, and contain pebbles which are allowed to be rolled chalk flints. If we could venture to add to these statements, that the order of succession among the strata of the tertiary series was exactly that of the successive emergence of the chalk, green sands, Weald clays, and Hastings sands, the hypothesis would stand on much firmer basis than is afforded by the above favourable circumstances. After an impartial consideration of the case, we have not been able to trace such a clear dependence of the successive members of the tertiary series upon the nature of the secondary strata successively wasted, as is implied in the hypothesis, that the gradual wasting of the Weald has furnished the materials for the gradual filling up of the basins of London and Hampshire. CONTRACTION OF THE EARTH'S SURFACE. 597 Chalk, the secondary stratum liable to be first wasted, and conse- quently to yield the materials of the lowest tertiaries, has furnished only a mass of flints interspersed among the variegated sands and clays, (with very little calcareous matter,) such as might claim origin from those strata of the Weald which were the last to undergo the influence of littoral agitation. The lower group of the Weald should have left a predominant mass of sands above the other deposits in the tertiary basins. It may be replied, in favour of the hypothesis, that the fine par- ticles of chalk might remain suspended, or be entirely dissolved in the water, until the period of the formation of the London clay, which is partly calcareous ; that the coloured sands associated with flint pebbles were derived from the green and iron sand groups ; and that the uppermost deposit of the tertiary groups may have consisted of sand which has since been removed. Principal Objection to it. Perhaps the most formidable of this class of objections is the total and absolute deficiency of any of the organic remains of the Wealden rocks (except in rolled chalk flints) in any of the tertiary deposits in question. This applies especially to the tumultuous deposits of sand and shells which lie above the chalk ; for here surely some of the numerous organic fossils of the green sand system, or some few fragments of the rocks, of the Hastings sands, with plants, shells, or bones, should have been found. Some recognizable specimens of the shelly marbles of the Weald clay ought, in some one locality or other, to have been discovered in the argillaceous beds which form a predominant feature in the tertiary basins. If it be remembered that we are here speaking of very contiguous districts, that the distance which the materials can be supposed to have been removed is only a small number of miles, and that it is matter of common observation, that by some currents or other, whether diluvial or alluvial, of transient or prolonged dura- tion, vast quantities of organic remains, separate, or embedded in recognizable masses of sandstone, limestone, shale, and ironstone, have been drifted fifty or one hundred miles ; it must be allowed that the total absence, from the tertiary strata, in all situations yet examined, of any fragments of the Wealden rocks or fossils, is a very serious difficulty to the reception of an hypothesis which de- rives the one from the other. Hopkins on the Weald. Mr. Hopkins has made a successful application of his theory of elevation of the strata, by the expansion of limited areas, to the phenomena of the Weald and the Bas Boulonnais, which is con- 598 VOLCANOES AND EAKTHQTJAKES. nected with it geologically. In this large elliptically elevated area, 150 miles long from east to west, and 40 miles broad from north to south, (within the chalk escarpment,) Mr. Hopkins recognizes, besides the general broad anticlinal slopes, which determine the main features of the district, several lines of flexure, and fracture, and anticlinal axes ; and he also defines some of those transverse lines of movement, depending on the main axis and boundaries of the district, which are directly deducible from his theory. He combines with the elliptical elevation of the Weald, the more elongated system of parallel movements of the Isles of Wight and Purbeck. The remarkable breaks in the bounding chalk ranges which give passage to the rivers flowing from the Wealden northward and southward, are shown to correspond in situation with cross fractures, indicated by theory, and sometimes rendered probable, and occasionally proved, by observation. One considerable decisive and simultaneous move- ment is appealed to for the dislocations of tbe elevated mass, and for the production of its main physical features, but there is still a ne- cessity of admitting a slow and gradual continental elevation to account for the denudation of the district.* * Geol. Trans., vol. vii. 5 4 375. General section of the Wealden, showing the probable extent of denudation. 1 Hastings sand. 2 Weald clay. 3 Lower green sand. 4 Gault 5 Upper green sand and chalk. EFFECTS OF HEAT. 599 CHAPTEE XIX. PERVADING EFFECTS OF HEAT. The investigations which have now been traced, lead to a general view of the earth's interior condition, which may be thus expressed. I. Whatever may have been its earliest cosmical relations, it ap- pears first in geological history as a spheroid of revolution, whose parts have taken their relative place under the joint influence of gravity to the centre and rotation on an axis. The density increases toward the centre, the surfaces of equal density are elliptical to the same axis as the external oblately spheroidal surface. II. This spheroid cools by radiation into the celestial spaces ; and by this consolidation begins at the surface, and brings into existence the variety of molecular aggregates which diversify the exterior crust of our planet. III. Contraction of the whole mass follows, but unequally in the solid external and liquid internal parts, so that either separation takes place between them, or the crust is pressed into accommodation with the interior. In the latter case, depression of the surface would result. In the former case, it may be admitted that gas, extricated from the solidifying mass, might uphold, at least temporarily, the solid arch of the crust. Thus the earliest inequalities of the surface would be occasioned ; and from the beginning a continual system of reciprocal depressions and elevations would be established by that " reaction of the interior of a planet on its surface," which is regarded by Humboldt as the most general aspect of the earth's volcanic force.* IV. In the earlier periods of the earth's contraction, these pheno- mena of elevation and depression must be supposed to have been of a generalf character, at first absolutely, and afterwards comparatively free from local inequalities of consolidation. The consequence would be, that the surface of the spheroid would be wrinkled by folds of elevation and depression, growing more and more deep, and with the progress of time more and more complicated. In remarkable har- mony with this view, is the well-known fact of the amazing frequency of anticlinal and synclinal and more complicated flexures of the palseozoic strata in all parts of the world flexures often completed before the close of that period. V. In later periods of the earth's contraction, local inequalities of * Humboldt, in his great work " Kosmos." t It is necessary to warn the reader that, in this treatise, the word general has the meaning given to it in exact science. It comprehends the whole area, and all the special cases, of the problem in hand; not merely the greater proportion of them, for which such words as usual, frequent, common, are suitable. 600 PEBVADING EFFECTS OF HEAT. consolidation partly dependent on the earlier flexures, partly pro- duced by the inequality of molecular aggregation (as, for example, by the separation of different orders of silicates) must have over- come the generality of the phenomenon of reciprocal depression and elevation, and limited them to separate areas or districts, in which one or the other of their opposite effects might take pface and in which one might follow the other so that the same tract might be alternately raised and depressed. VI. In nearly all cases the depression must be supposed to be real and gradual, that is to say, part of the earth's surface affected by it must be gradually carried nearer to the centre than it was be- fore ; the elevation may have been in many cases only relative and gradual, but in others real and unequal, that is to say, the area may have been removed farther from the centre than it was before, by a force of local pressure, subject to inequality and cessation, (as gaseous pressure). In some cases of real depression, and in many more of real elevation over a limited area, the solid crust must be supposed to have been extended ; in the former case under the in- fluence of greater heat, (as being nearer the centre than before,) in. the latter case under the contrary condition. VII. In a case of the real elevation of a given area by the general upward pressure of a liquid the crust would be extended, beyond a certain strain it would break, the broken parts would slide on one another, so as to occupy a larger area, and the result would defaults, according to the laws already indicated, pp. 34, 35. On the subse- quent withdrawal of the liquid pressure, from whatever cause, the subsiding of the arch, whether broken by faults or not, would occa- sion lateral pressures and probably outward flexures, especially to- ward the limits of the elevated district. VIII. In a case of real depression of a given tract, followed after a long interval by elevation there, the effects would vary according to the area moved and the vertical range of the motion. If the area were so extensive as to include a large arc on the earth's surface, the crust would subside into a smaller area, and be wrinkled, or otherwise affected by compression and augmented heat. On the re-elevation of such an area, faults would probably be produced. (This seems to have been the case in regard to many of our coal fields, whose flexures are traversed by later faults.) If the subsiding area were small or narrow, and the downward movement great, the rocks would sink into a larger area, and faults might be expected. On the re-elevation of such a tract much local disturbance and com- plicated internal movements among the masses of the rocks might probably follow. (This may, perhaps, have happened in the Belgian and Somersetshire coal fields.) IX. The influence of these conditions may not yet have passed ON STEATIFIED EOCKS. 601 away. It may still be the case that Scandinavia is rising, as Lyell admits, and the low islands of the Pacific sinking, as Darwin believes ; not in either case on account of volcanic excitement, strictly so called, but by reason of internal changes of density and local accumulation of aeriform fluids, both the consequence of slow refrigeration. That the earth is still partially fluid within may be seen in the cone of more than one volcano ; that it is partially and to a great depth solid in certain regions and along certain lines, the broad areas and long tracts of ground shaken by earthquakes abundantly prove. As long as this mixed condition of the interior obtains, there can be no doubt of the probability of further slow and small vertical move- ments in the crust of the globe. Consolidation and Alteration of Stratified Rocks. In a preceding section we have seen the effects produced by the plutonic rocks upon the strata which they penetrate ; effects which suggest to our minds so vivid an impression of the action of heat, that even in the absence of all other arguments from facts, we could not refuse to allow that those rocks had been local centres of heat. The independent evidence arising from the composition of the rocks satisfactorily confirms this inference, and permits us to apply it in circumstances when the actual proximity of igneous rocks cannot be ascertained. These effects seem to be reducible to several cases, de- pending on the degree of heat communicated, and the substances operated on. Effects of Plutonic on stratified Rocks. 1. The consolidation of stra- tified rocks is exemplified in the induration and contraction of shale, and in the development of new faces or joints in it, which sometimes meet one another rhomboidally, sometimes follow the columnar re- lations of the adjoining basalt, and sometimes imitate slaty cleavage. 2. The partial fusion of some part of the substance of a rock, so as to conglutinate its grains, and solidify and harden the whole mass. Thus sandstone is converted to a granular quartz rock. 3. The complete fusion or vitrification of the rock ; thus convert- ing shale into Lydian stone and sandstone into a kind of jasper. 4. The complete fusion and consequent rearrangement of the particles into granular or crystalline forms, as in the instance of common chalk in Ireland, common limestone in Yorkshire, the Isle of Skye, and Carrara. 5. The generation of minerals not before existing in a distinct state in the substances affected. The production of pyrites, asbes- tus, anthracite, plumbago, garnet, &c. along the contact of igneous and aqueous rocks, is a very characteristic and general effect which 602 PEEYADING EFFECTS OF HEAT. appears to result from the actual transfer of the metallic and other matter through the solid substance of the rock, in virtue of electric attractions which may be considered as imparted by the heat. If Von Buch's notion of the impregnation of rocks with magnesia in the vicinity of augitic trap rocks should eventually be substan- tiated, it must be considered as a remarkable example of this electric transfer. 6. The sublimation of some portion of the neighbouring substances. Thus the charring of coal, the desulphuration and the debitumeniza- tion of shale, are very directly connected with the heating power of the igneous rock, but it is probable that some peculiar conditions were required for such effects in the submarine depths, where most of these operations were performed. Relation of Igneous Rocks to Convulsions. The almost universal coincidence of convulsive dislocation of the strata with eruptions of plutonic rocks, seems enough to prove their common dependence upon one pervading cause of internal movement. In the same man- ner as the modern earthquake precedes the eruption of lava, so the ancient convulsion preceded the injection of plutonic rocks. Also precisely as in the present day the earthquake shakes countries far removed from volcanic centres, so in more ancient periods many tracts were convulsed but not filled, at least near the surface, with melted rocks. As far as at first appears, the common dependence of the two orders of effects upon one cause, is merely to the amount that the mechanical transference of melted rocks has been effected by the same internal pressure which dislocated the strata ; whatever occasioned the pressure, and whatever was the cause of the fluidity of the rocks. Various mechanical modes may be conceived, by which such pres- sure may have been occasioned, and various conditions assumed for the production of melted rocks, and these may be wholly distinct from one another ; but the exhibition of these rocks along the lines of convulsion can only be ascribed to the same mechanical cause which produced the convulsion. Metamorphism of Rocks. structural Metamorphism. In considering the characters of stra- tified rocks, we find several circumstances which it is difficult to ex- plain without reference to some powerful action subsequent to the deposition of the strata. The consolidation of these rocks, however commonly it occurs, is a phenomenon worthy of attention. In daily experience, we see some degree of consolidation effected in calcareous deposits by the concretionary or crystalline coherence of the par- ticles. But we scarcely perceive any induration of clay, or congluti- 0~8 METAMOHPHIC BOOKS. 603 nation of sandstone, without enormous pressure or the application of heat. By the subsidence of the strata to some thousands of feet or yards, which has unquestionably happened in very many cases, these two favourable influences were brought into action. The lower strata were upon the whole sunk to the greatest depth, and experienced the greatest amount of pressure and heat, and these are on the whole the most consolidated ; the clays have become slate, the sands quartzitic. The jointed structure of rocks, as already observed, (pp. 40, et. seq.*) may have been much aided by heat. Their structure, in fact, indicates the mutual approach of the particles, a process likely to be aided by pressure and heat ; it is not surprising, therefore, to find the joints in great perfection among some of the older strata. Similarly, we find that beautiful structure in slate expressed by the term " cleavage " (p. 43,) most developed in the older strata, but with this peculiarity, it is most perfect in the fine grained argil- laceous strata, least manifest in the coarse gritstones or conglome- rates which alternate with them. In the British Islands this structure is almost absolutely confined to the palaeozoic series ; though, parallel to certain dikes, mesozoic strata may show it slightly. It is, however, not merely an effect of time, but due to some peculiarity in the history of those rocks. If the reader will now cast his eye on the diagram (p. 260), and the explanation which accompanies it, he will perceive that the limestone strata under the coal basin of South Wales, which were deposited nearly at the sea level, were sunk during the latest palaeozoic periods about 12,000 feet below the surface. In these, a partial slaty cleavage appears. The old red strata, several thousand feet thick, which were still deeper, and more heated, are more marked by cleavage ; and the Silurian and Cambrian, still deeper by thousands of feet, are even more distinguished by that structure. It is chiefly in what were the deeper parts of the basin that this effect occurs, for on the north side of the South Wales coal field, the upper silurian strata and the old red beds are often free from cleavage, and it is there only partially exhibited in the lower silurian. Farther to the north, as in the district of the Malvern hills, Woolhope, Abberley, Dudley, the silurian rocks and all above them are free from cleavage, unless in a very slight degree, and along some small and limited spaces. Yet these districts are marked by great and violent flexures, and even reversals of the strata, so that pressure seems here to have failed entirely in producing cleavage. This is the more curious, because, in the same country, parallel to the once heated greenstone dike of Brockhill, the old red shales have admitted a rude cleavage. In these districts, there is no 604 PEEYADING EFFECTS OF HEAT. reason to admit more than a few thousand feet of depression (5,000 to 8,000 feet). Still farther north, the Cambrian and lower silurian rocks of Charnwood Forest, and the base of Ingleborough, are full of cleav- age, crossing great curvatures of the strata. Those curvatures pre- ceded the formation of old red sandstone. There is absolutely no cleavage in any of the upper or middle palaeozoic strata, which in the utmost depression which we can trace, may have been some 5,000 or 6,000 feet deep in Yorkshire, and some 8,000 feet deep in Lancashire, but the Cambrian and silurian rocks in which cleavage occurs must have been twice as deep. From considerations of this kind, we are led to admit that depth in the earth that is, the heat and pressure, and molecular action favoured by depth is one of the main agencies favourable to the generation of slaty cleavage in the strata. Pressure is clearly favourable. For the direction of the planes of cleavage is parallel to the great axis of movement in the district (p. 45), and our own researches, enlarged by the investigations of Mr. Sharpe, leave no doubt that the compression of the rocks in the direction at right angles to the cleavage planes is real and considerable.* Mr. Sorby has even succeeded in producing by artificial pressure a representa- tion of cleavage structure in a mass of matter originally quite desti- tute of it. Combining these ideas, we arrive at the following general view. A large area of country subsides parallel to a certain axis of movement, and is transferred to a hotter and a narrower space, hotter, as compared to the surface, narrower as the chord is shorter than the arc. End pressure operates on all the strata ; heat more particularly on the argillaceous parts ; the plates of mica, scat- tered through these strata, are by the pressure made to assume positions not all parallel, but tending to parallelism, and thus effec- tually causing fissility in the stone. f Cleat. Though, as before observed, there is no slaty cleavage in the coal strata of the northern counties, or, indeed, in Wales, there is a structure of the same order in the substance of coal, called "cleat," which is quite as regular, and extensive, and due to as general a cause. This consists in . a series of parallel fissures, often very fine and numerous, which cut across the strata of coal, in planes nearly vertical to the strata, and in directions seldom deviating much in the large area of a coal field. In the northern coal fields this direction is N\N.W. and S.S.E., or nearly so. It scarcely occurs, except in the coal, is not affected by faults, and is not parallel to axes of movement, varies in character from bed to bed, but seems due to crystalline forces, excited uniformly over large * Sharpe, in GeoL Proceedings. f Sorby, in Geol. Proceedings, 6,042 4,291 3,846 927 - 3,180 26. Falunian -f jPP er - 25. Parisian 23. Danian 22. Senonian 21. Turonian 20. C enomanian 19. Albian 18. Aptian 17 Neocomian 13. Oxfordian 12. Callovian 10 Bajocian 9. Toarcian 8. Liasian 7. Sinemurian . ... 3. Carboniferous 1. Silurian < ^pper 18,286 18,286 If to these we add the vertebrata and articulata, the total number of known fossil species would be about 24,000. " Twenty-four thou- sand facts," says D'Orbigny, which establish the succession in all parts of the globe of as many distinct groups of animal life, following one another in a settled order of geological time.* Confining our attention to the vertebrata, we may represent the rate of change by a diagram like the following: * Cours elSmentaire de Palseontologie et de Ge'ologie, torn, ii., p. 250-251. 624 STATE OF GEOLOGICAL THEOET. PERIOD OF MAN Cainozoic, or Tertiary Life Periods. f "* Megacerian Ages of Extinct ' Mammalia. \ Mammothian t Palasotherian Mesozoic, or Secondary Life Periods. Mososaurian Ages of Extinct Saurians. Megalosaurian Teleosaurian Palseosaurian Palaeozoic, or Primary Life Periods. Palaeoniscian > . . Ages of Extinct Fishes. Megalichthyan Pterichthyan Palichthyan Proichthyan PROZOIC? PERIOD. In this table, the elements of thickness of the several great groups of strata is introduced; it snows the greater thickness of strata corresponding to a given change of life, in the early than in the later ages of the world. If we measure geological time by thickness of strata, the changes of life have been most rapid in later periods; if we take life-changes for our scale of time, me- chanical agencies were more active in early periods. This latter conclusion is most in harmo ny with the general views adopted in this treatise. LIMITATION OF INQUIRY. 625 6. The successions of convulsions in the same physical region may be very properly mentioned as a vague indication of the lengths of geological periods ; but cannot at present be employed in a more exact manner to determine their duration. 7. The alternation of marine and fresh water products is another of those grand phenomena, which, whether rightly or not, is sure to make a deep impression on the mind ; though the rarity of the case, and our ignorance of the principal efficient circumstances, must wholly exclude it from among the data for accurate calculation of geological time. 8. The same may be said of the alternation of aqueous arid igneous products. 9. The metamorphism of rocks, &c., in consequence of the local or general effect of heat, may possibly one day be sufficiently under- stood to permit some attempt towards determining the intensity and rate of the communication of heat, and thus more or less directly bear upon the question of time. The chemical changes of organic remains are evidently less related to time than to other circumstances, such as, the original nature of the body, the sort of substance in which it is embedded, and proximity to sources of mineral impreg- nation, whether by aqueous or igneous solution, or electrical transfer of solid ingredients. Successive Conditions of the Globe. The object of geological researches has been till lately very little understood by those not directly conversant with the subject ; and even professed geologists do not always restrict their inquiries within just bounds. It is difficult for a speculator to believe that geology may become a very important branch of natural science, though it should wholly disclaim the investigation of problems concerning the creation or concentration of the matter of the globe, or the establish- ment of the laws of the universe. To know the successive changes which the globe has undergone, and thus to trace a retrospective outline of its successive conditions, is actually attempted by geology; but the very processes employed in this enterprise are founded upon the recognition of the existing laws of nature, and altogether exclude the popular notion of a chaos, and the philosophical hypothesis of an atmospheric expansion condensing to a solid globe. limitation of Geological Inquiry. Undoubtedly the progress of legitimate geology teaches us that the same laws of nature have operated on this globe under very different circumstances, as to tem- perature, relation of land and sea, animal and vegetable life, and many other things ; and it is become a proper problem for geology to dis- cover these circumstances. In this point of view, the reflections of 2s 626 STATE OF GEOLOGICAL THEORY. Leibnitz, and the mathematical labours of Laplace and the astrono- mers, become of great value, since they help to fix conspicuous land- marks for the guidance of the surveyors in this large field of science ; but let no one delude himself with the notion of discovering, by geological processes, the emerging of the harmoniously adjusted terraqueous globe from a former state of chaos. It is certainly not a philosophical, and surely cannot be thought a religious notion, that man shall ever discover among the works of God, the traces of a period when His Divine attributes were first awakened to rescue his creation from anarchy. Geology takes for granted the existence and collection of the matter of the globe, with its supernatant ocean, and its enveloping atmosphere. Except in the degree of influence which circumstances permit them to exert, it takes for granted the uni- formity of action of all material causes. The investigation of miracles can never be admitted into natural science. The dimensions of the globe have remained constant since the days of Hipparchus ;* for Laplace has shown that the length of the day has not sensibly varied since that time, which must have happened if the diameter had perceptibly changed : if the globe had contracted, the diurnal period would have been shortened, and vice versa. This is usually considered a very formidable argument against the doctrine of internal heat, and its corollary, secular refrigeration and contraction, to which theorists have very freely resorted, as the pro- lific source of all subterranean movements, changes of superficial temperature, elevation of continents, volcanic eruptions, injection of igneous rocks, mineral veins, &c. Fourier's researches, however, into the mathematical theory of heat, show that, under the condi- tions of sensible constancy of dimension, and variation of superficial temperature according to solar influence, we are at liberty to suppose the existence of deep-seated heat of any intensity, provided there be direct indications of corresponding augmentation of sensible temper- ature below a certain depth. Such indications, it is very generally allowed, are presented by the observations in mines and collieries in Europe, Asia, and America. Secular Refrigeration. With regard to secular refrigeration, the experience of two thousand years undoubtedly shows that its effect in contracting the earth's diameter has been for that period insen- sible ; but, first, it must be observed, that the hypothesis supposes the effect of refrigeration to be a contraction of an internal nucleus, and a consequent separation between it and the solid crust, which continually increases until the crust is broken or bent by a convulsive collapse ; secondly, it is sufficiently evident that, by the accumulation of nonconducting materials over a source of heat, the diminution of * Born 160 B.C. VOLCANIC ACTION INTERNAL HEAT. 627 this heat must become continually more and more slow, so as at last to be insensible even in very long periods. If, then, it should appear that the leading phenomena of the ancient history of the earth can be well explained by help of these suppositions, there is nothing in the mathematical theory to prevent their provisional adoption, on the basis, not unfrequently employed in natural philosophy, that they serve to explain many phenomena. Volcanic Action. It is by no means necessary to couple with the hypothesis of internal heat, the doctrine that volcanic action arises from this cause only : the various chemical characteristics of volcanic action must be examined upon their own evidence ; and it does not appear that the hypothesis of particular chemical antecedents to vol- canic operations is at all deprived of its applicability, or rendered superfluous, by admitting the existence of intense internal heat. On the contrary, under the influence of a high temperature, the admis- sion of oxygen and water would still produce upon the fluid metal- loids and metals the effects usually ascribed to such a cause, and perhaps more easily than if they were solid, and the results would still be proportioned to the circumstances of the locality. Displacement of the Earth's Axis. The moderation which geologists were so slow to learn, has prevented them from reviving the ancient speculation which ascribed the leading phenomena of geology to an extensive shifting of the earth's axis, and consequent displacement of the ocean. To be consistent, we must suppose this mighty oper- ation to have been many times repeated before the occurrence of the deluge which it was invented to explain. Perhaps the probability that every part of the globe equally requires this displacement of the axis, but requires it in different directions at the same time, may be sufficient to prevent its resuscitation. It is too much, however, to treat it as an absurdity, merely upon the ground that the shells of equal density within the globe have their axes, at the present mo- ment, nearly coincident with those of the surface ; for, with this condition, irregularities do take place in the distribution of the exterior parts of the planet, as in the case of volcanic eruptions, and any material displacement of weights of the surface must (slightly) affect the axis of rotation. internal Heat of the Globe. As Mr. Greenough has observed, " be the cause what it may, the fact is certain, that the temperature of the crust of the earth was higher when the coal measures were deposited than now, and we have reason to think it was still higher at antecedent periods. That a considerable degree of heat still exists, either partially or generally, at no great distance from the surface, appears from thermal springs and volcanoes." * * Geological Society's Proceedings, 1834. 628 STATE OF GEOLOGICAL THEOET. Origin of Terrestrial Organic Life. In accordance with this view is the common opinion, that geological inquiries have discovered traces of a period in the history of the globe, when neither animal nor vegetable life was established upon it. This opinion, ably ex- pressed by Dr. Buckland in his Vindicice Geologicce, is chiefly sup- ported by the facts observed in studying the lower paleozoic strata. The view of the subject which is most consonant to the course of inferences adopted in this treatise has been already sufficiently expressed in the review of the primary strata. Whatever may be the truth on this point, it is certain that the successive systems of organic life, both terrestrial and aquatic, animal and vegetable, show the same general principles and relations as that to which we belong. Geology has disclosed various and remarkable animals, not paralleled in existing nature, and plants of singular forms, but nothing which deviates from those general laws of struc- ture and function which govern the actual organic creation. The plants and animals of different geological periods do not differ more from one another than those in opposite climates, or even distant localities at present. There is even to be observed among the several successive systems of organic remains some real analogy to existing local faunas and floras. The oolitic fossils have, perhaps, a greater resemblance, for instance, to the living productions of Australia and the Indian islands than to those of any other situation ; while the plants and uniones of the northern English coal tracts remind us of the physical characters of the American continent, rivers, and islands. Periods of Convulsion and Repose. There is, perhaps, no point of theoretical geology more certainly established than that, in any given small area of the surface of the globe, long periods of ordinary action of natural causes have been several times interrupted by epochs of extraordinary disturbance ; that the relation of the level of sea and land has remained for a long time the same, or very gra- dually changed, and afterwards been altered by internal convulsions. It is also admitted that this law has an extensive, though then less exact application ; that the periods of ordinary and crises of extraor- dinary action were respectively contemporaneous over very large regions of the globe, and even with respect to some of the cases admit of general application. It appears, also, that the nature of the strata deposited differs more or less according to the several successive periods, and that the races of organic remains, in several important cases, are subject to contemporaneous crises. On this evidence, joined to some theoretical considerations, is founded the modern admission of the doctrine of alternating periods of convulsion and repose ; a doctrine which was held by ancient philosophers, revived by Leibnitz and Hutton, and illustrated by Cuvier and De NATUBAL AGENCIES. 629 Beaumont. Perhaps this view of the subject was never more clearly expressed than by Leibnitz, whose just sense of the philosophy of geology has been placed in a strong light by Mr. Conybeare. His view is, that the powerful agencies exerted in displacing and altering the solid crust which gradually thickened over the ignited nucleus have many times renewed the face of the young globe by the erup- tion of concreted igneous rocks from below, and the deposition of stratified rocks by water above ; and that the globe was, by these processes, more and more diversified with mountains and valleys, and subjected to various physical conditions ; donee quiescentibus causis, atque cequilibratis, consistentior emergeret rerum status. Uniformity of Natural Ageiicies. Lyell's pictures of the successive conditions of the globe are all drawn to one scale, from the un- varying standard of its present state. His hypothesis admits local alternations of ordinary and critical action, but denies anything like a general paroxysmal effort of natural agents ; nor is there, between the ordinary and critical stages of his processes, any conspicuous difference. The principle of his system is, that the disturbing inter- nal forces exert themselves in irregular succession beneath all the points of the surface of the globe ; and that the ordinary chemical and mechanical agencies of nature are thus modified in their inten- sity, and diversified in their effects, and applied to produce an end- less series of destructions and renovations, which, upon the whole, compensate one another continually. In this system the postulate required is unlimited duration ; in the other, a varying momentum of natural agencies according to differ- ence of condition ; the one is a system of continual, the other of intermittent compensation. Nature offers to our view examples of both these cases, and on a large scale : it is therefore very unwise to assume one or the other on account of our notion of its greater pro- bability ; we must see which of the systems finds support from the facts of the case. It has been already seen that our proofs of the periods of time elapsed are neither clear, satisfactory, nor complete ; much of the evidence on this subject is in unknown terms ; but esti- mates derived from probable views of the mechanical composition and organic contents of the strata do not appear to warrant the pos- tulate of unlimited duration. On the contrary, be the duration of geological periods what they may, it is clear that the earth has successively undergone great phy- sical changes ; terrestrial agencies must therefore have operated upon it with a corresponding variation of effect ; one of these changes of condition, that of superficial temperature, is not explicable by any of the known periodical inequalities of the solar system, or the irre- gular fluctuations of surface elements of climate, but seems in har- mony with the general theory of internal heat, gradually becoming 630 STATE OE GEOLOGICAL THEORY. less and less sensible as the external crust thickened, and the surface of the globe approached to a state of equilibrium. Successive Conditions of the Materials of the Crust of the Globe. The question of the origin or first condition of the elementary ingredients of earthy and metallic substances, if capable of solution, must be referred to another science ; but inquiries into the successive conditions of the mineral substances which appear in the crust of the globe is one which, in some shape or other, must be often proposed to a geologist. It is difficult to stop at the recognition of the igneous origin of some rocks, the aqueous production of others ; we cannot avoid examining whether any evidence can be found for determining a prior condition of the substances contained in these rocks. Facts of great importance here come before us ; we see examples of new rocks produced by heat from aqueous deposits, and sedimentary aggregates of the disintegrated ingredients of volcanic and plutonic masses. The deposition of limestone offers very re- markable variations ; and it is impossible to consider the composi- tion of the minerals in crystallized rocks without feeling that the resources of chemistry are or may become capable of advancing us one more step in the analysis of the series of conditions through which the solid ingredients of the globe have passed. The time is not long gone by when Werner, who, with far less moderation than Dr. Hutton, wished to begin at the beginning, could find thousands of followers in the startling dogma, that all the rocks observed near the surface of the earth, were deposited from one chaotic fluid, which first permitted the crystallization of granitic and other rocks, and afterwards produced the secondary sandstones, shales, and limestones. It is possible that even yet there may be persons who can believe that these secondary sandstones were produced by a chemical decomposition of the ancient ocean ; which, to answer all the unreasonable demands upon its powers, must have been endowed with more than the creative energy of a Brahma, and capable of surmounting every chemical and mechanical impossibility of crys- tallizing into sand, condensing into limestone, and subliming into metal ! Leibnitz, and a large portion of modern geologists, also attempt to fix something like a beginning to their system, a point of geolo- gical time when the change from a fluid to a solidified surface per- mitted the development of that series of intermitting igneous and aqueous actions, which has brought the globe by many revolutions to its present state of comparative repose. The followers of Dr. Hutton see no such commencement to their series of terraqueous effects ; they find no physical traces of a beginning, nor any change SUCCESSIVE CONDITIONS OE CEBTAIN SUBSTANCES. 631 of operation which should give the prospect of an end of this series of effects proportioned to the time elapsed. Yet, as one hypothesis admits locally, periodically, and repeatedly, what the other supposes to have happened generally and in one succession, there is no neces- sary disagreement in the interpretation of particular cases. This is not always remembered by those who engage in the controversy con- cerning the uniformity of natural effects. Successive Conditions of Certain Substances. If we trace back the history of the materials of the sedimentary sands and clays now in process of formation at the mouths of rivers, along the sea-coasts, and in other situations, we shall find that these materials are often derived from ancient superficial deposits left by local or extensive floods ; examination proves that the materials of these deposits were often obtained by the violent breaking up and attrition of far more ancient previously solidified strata ; in several instances it is manifest that these are nothing else than the oceanic accumulations derived from disintegrated primary strata, or of disintegrated pyrogenous rocks. As an example, we shall quote a well-ascertained series of facts, which leave no doubt of the many changes of condition through which the granular ingredients of modern sedimentary deposits have passed. 1. The Ouse, Trent, and other great rivers connected with the Humber are so filled with the finer parts of the sediments which fall into the sea along the wasting cliffs of Holderness, that their flood waters, when introduced to the lower ground along their banks, deposit a great thickness of valuable soil. The sandy and coarser parts of the sediment are collected in various irregular positions in the Humber and along the coast, and the pebbles remain on the beach, or follow its descent for a small distance into the sea. 2. The diluvial cliffs, which by their destruction afford this rich supply of fertile warp and sterile sand, contain fragments of all the rocks in north-western Yorkshire, that is to say, basalt, limestone of many kinds, cherts, sandstones, fine grained and coarse grained millstone grit, shales, ironstones, and coal ; fragments of granite, hypersthene rock, and old slates from Cumbria ; all embedded in a vast thickness of sands and clays composed of the same comminuted materials. 3. The millstone grit, fragments of which occur in this diluvial mass, is a compound of felspar, quartz, and mica, with occasional admix- tures of other substances. These minerals are easily recognized as rolled and water-worn masses, derived from porphyritic granite, gneiss, and other such rocks. The felspar is always perfectly crystallized within, but the external surface is water worn ; the mica has lost its angles ; and the quartz fragments are only in the state of large grained sand. Plainer proof of mechanical aggregation of ingre- dients which once composed a crystalline felspathic rock, cannot be 632 STATE OF GEOLOGICAL THEOET. desired. Many such instances are known, and the inference is gene- rally allowed. Extension of this inference. As far as the results of a careful examination of ordinary sandstones can be trusted, there is no reason to refuse to them, as a general rule, the same kind of origin as to coarse millstone grit. Most of them have the same ingredients, though it frequently happens that the felspar is in a state of decom- position. Shales and clays are to sandstones what the fine warp in the water of the Humber is to the sands in its channel. We may then venture, in a moderate spirit of generalization, to assume, that sedimentary sandstones and shales have originated in the mechanical action of water upon the disintegrated granular ingredients of pyro- genous rocks. Any one who has sufficiently observed the varieties of sandstones and shales on the one hand, and of stratified primary rocks on the other, and considered the nature and amount of the changes pro- duced upon them respectively by heat, or properly weighed the observations and reasonings of MacCulloch, will have no difficulty in admitting the views as to the origin of the latter class of strata advocated in former parts of this essay. We are therefore conducted, apparently by a legitimate process of induction, to the conclusion that all the stratified rocks, limestone and some particular strata except ed, are derived primarily from the decomposing agencies of nature operating upon pyrogenous rocks ; and we thus find a natural limit to the series of conditions through which these materials have passed. This conclusion, though perhaps less distinctly stated, is essentially recognized in modern geological systems, and is felt to be substantially true, though it still leaves many things to be explained. Origin of Limestone. An inquiry as to the origin of the vast masses of stratified limestone is a subject of considerable difficulty. In a great majority of instances the limestone formed at the present day is the result of chemical forces, or of vital forces controlling chemical action; and the same was probably the case in earlier periods. In particular instances calcareous deposits have partially or wholly a mechanical origin ; as when a stream brings down the waste of a chalky or oolitic district, and deposits the sediment in a lake ; or when the currents of the ocean drift shells and other marine exuvia3 and lodge them in the midst of coral reefs. Observers of the growth of coral islands have detected several facts as to the intermixture of decomposed fragmentary and entire calcareous marine exuviae with coral rock, which seem to render probable the opinion of geologists, that some of the older secondary and transition limestones are in places only magnificent coral reefs. Perhaps nowhere has the mechanical origin of limestone been RESULT. 633 assumed to a greater extent than in the Huttonian system of geology ; for it seems to be an essential part of that system, that the stratified limestones are nothing else than triturated shells and other calcareous exuviae. By those who adopt this view, chalk, the least compacted kind of limestone, is usually taken as an example. It is sometimes difficult to avoid imagining that the powdery magnesian limestone is a recomposed rock, derived from the ruins of magnesian beds of carboniferous limestone. But this cannot be a true account of the matter ; for, 1, there ought to be far less magnesia in the compound ; 2, this is in some instances an atomic combination of carbonate of magnesia and carbonate of lime ; 3, this limestone is often really a granularly crystalline rock (like the older magnesiferous beds of mountain limestone), and seldom appears to justify the least sus- picion of the mechanical agency of water. But nothing is more certain than that of all the strata yet disco- covered, limestone is exactly that which, by the regularity and con- tinuity of its beds, by the extreme perfection of its organic contents, and by the absence of proofs of mechanical action, gives most com- pletely the notion of a chemical precipitate. It appears sufficiently probable, in several instances, that the quantity of limestone depo- sited in a given geological period was least towards the shores, and greatest towards the deep sea ; exactly the reverse of what happens with the mechanical deposits of sandstone and shale ; it may, there- fore, be viewed as an oceanic deposit, resulting from a decomposition of sea water, aided in many instances to a wonderful extent by the vital products of zoophytic, echinodermatous, and molluscous ani- mals. According to this view, it is easy to understand the repeated production of limestones of the same mineral character at different periods ; nor need we feel surprised that, occasionally, limestones of the same age differ in properties. However, all these views end at last in one, viz., that the earliest condition which we can assign to the carbonate of lime, is that of extrication from some solution of lime in water, by chemical or vital processes. And here, perhaps, it will be wisdom to pause, for though some have ventured to imagine that the lime might be derived from the decomposition of particular ingredients in primary igneous rocks, and others may suppose that the ocean would more directly obtain this with other ingredients from the oxidized fluid nucleus of the globe, such speculations are hardly within the pale of inductive geo- logy, and involve too many hazardous assumptions to be at present worthy of the notice of other sciences. General Result. The general tendency of geological reasoning is to establish the inference, that a large portion of the stratified de- posits have been formed from the wasted ingredients of pyrogenous rocks ; all the phenomena of volcanoes and ancient igneous eruptions 634 STATE OE GEOLOGICAL THEORY. prove that locally stratified deposits are reconvertible to crystalline rocks by the force of heat, and very generally alterable in character so as to approximate to the actual products of heat. Lyell puts this to the extreme, and supposes that the calorific energy of the interior of the earth is constantly acting, so as to reconvert sedi- mentary into crystalline aggregates, equal quantities in equal times, and thus to maintain a perpetual equilibrium between the liquefying internal and the solidifying external agencies of the globe. This speculation is much too poetical to be examined according to the dry rules of the Baconian philosophy : if the heat expended in this operation be obtained from chemical processes, these must gradually tend towards equilibrium ; if from a general internal reservoir of caloric, that reservoir must become less and less prompt in supplying the incessant demand: either of these effects operating through indefinite time must cause the gradual refrigeration of the surface of the globe, a consequence not favourable to the hypothesis of the uniformity and continual compensation of the effects of internal and external terrestrial agencies. APPENDIX, TABLES AND CALCULATIONS. PHYSICAL RELATIONS OF THE GLOBE AS A PART OF THE SOLAR SYSTEM. THE EARTH AND THE SUN. Figure of the Earth, a spheroid of revolution, with diameters as 298 : 299. Equatorial diameter 792-5648 miles. (Difference, commonly called the compres- Polar diameter 7899-170 f sion = 26-478 miles. Mean distance from the Sun, 95,000,000 miles. Obliquity of Ecliptic, 23 28'. Time in which the Sun returns to the equinox,) ) ( d. called the Equinoctial, or Tropical, or Civil j- 36 Zones j 11 37 18 269 225 16 21 379 Ratio of Num-^) ber of Oc- | currences to } Number of Species J 1-6 1-8 3-0 2-3 2-1 1-3 2-6 2-8 CONSTITUENT INGREDIENTS OF ROCKS. It has already been stated that notwithstanding the immense variety of rocks which solicit the attention of a geologist, a correct knowledge of only a limited number of mineral substances is sufficient to enable him to trace and recognize these rocks, and describe them satisfactorily to others. The following short list includes those that appear most essential for this purpose. It is hardly necessary to observe that the student will do well to endeavour to familiarize himself with these minerals, by considering the variation of their appearance and modes of combination with one another, and examining them in a crystallized, amorphous, and decomposed state. For this end he should often contemplate arranged cabinets of minerals, and collect fragments of compound rocks. A little practice will give him a knowledge of their characteristic forms, hardness, specific gravity, and ordinary optical characters. Quaiiz. Orthoclase Felspar. Mica. Hornblende. Actinolite. Augite. Hypersthene. Diallage. Olivine. Analcime. Schorl. Chiastolite. Chlorite. Green earth. Talc. Steatite. Garnet. Carbonate of Lime. Carbonate of Magnesia. Sulphate of lime. Muriate of soda. Bitumen. Iron, Oxide of , Sulphuret of CONSTITUENT INGREDIENTS OE EOCKS. 647 The hardness of minerals is expressed in the following convenient scale, of early recognizable species : 1. Talc. 2. Gypsum. 3. Calcareous spar. 4. Fluor spar. 5. Apatite. 6. Felspar. 10. Diamond. 7. Quartz. 8. Topaz. 9. Corundum. The specific gravity of a mineral is expressed by comparison with water. Thus, 2-5 in the case of felspar, shows that its specific gravity is twice and half that of water. Those geologists who have occasion to examine into the history of mineral veins, must, in addition, make themselves acquainted with metals, alloys of metals, and combinations of metal with sulphur, selenium, carbon, oxygen, and acids. To assist in the acquisition of the requisite knowledge of these minerals, the following statement of some of the modes of their occurrence in a con- siderable number of rocks many be found useful. The appearance of minerals in rocks is often much different from that which they bear in detached specimens. QUARTZ. Crystallized in double six-sided pyramids in the substance of granitic, por- phyritic, and other igneous rocks ; in six-sided prisms terminated by six-sided pyramids in mineral veins and in cavities in granite ; compact in veins ; nodular in amygdaloidal traps ; rolled masses in old red conglomerate, millstone grit,and grauwacke ; worn grains in sandstones, clays, certain quartz rocks, and coarse clay slates. Specific Gravity 2 6. Hardness 6, OKTHOCLASE FELSPAR. Primary rhomboidal crystals in granite, porphyry, trachyte ; composite and modified crystals in cavities of granite, and veins ; disturbed crystals in gneiss ; rolled crystals in conglomerate ; decomposed to porcelain clay in some'granites and sandstones. Colour, red, white, greenish. Specific Gravity 2-5-2-7. Hardness 6. MICA. Crystallized in brilliant elastic laminae, composing hexagonal plates in granite, porphyry, lava, and primary limestone ; disturbed crystals in gneiss and mica schist ; fragmentary scales in sandstone, sand, shale, and clay. Colour various. Specific Gravity 2-6. Hardness 2-5-7. HORNBLENDE. Crystallized in rhombic prisms with felspar, &c., in syenite, greenstone, basalt, also in hornblende slate. Colour black or green. Specific Gravity 3-2 to 34. Hardness 5"5. ACTINOLITE. Crystallized in long slender, often radiating prisms in hornblende slate, in veins. Colour green. Spec. Grav. 3'0 to 3-3. Hardness 6. (A variety of Horn- blende.) AUGITE or PYROXENE. Crystallized in rhombic prisms with felspar in augitic green- stone, augitic basalt, melaphyre, lava; also in primary limesltone. Colour black, green. Specific Gravity 3-3. Hardness 6. HYPERSTHENE. Crystallized with felspar in hypersthene rock, hypersthenic syenite, thenic greenstone. Colour black, green, gray. Specific green. Specific Gravity 3-3. Hardness 6. YPERSTHENE. Crystallized hypersthenic granite, hyperst Gravity 34. Hardness 6. DIALLAGE. Crystallized with felspar in gabbro or diallage rock; obscurely crystallized in serpentine; fine grained in serpentine. Colour green. Specific Gravity 3'1. Hardness 4*5. OLIVINE. Crystallized and granular in lava, basaltic and other igneous rocks. Colour greenish. Specific Gravity 3-2. Hardness 6. EPIDOTE. Crystallized in slender prisms, or granular in syenitic and other igneous rocks. Colour usually pale green. Specific Gravity 3-4. Hardness 6*5. ANALCIME. Crystallized in cuboidal forms in lava, basaltic, and other igneous rocks. Colour pale. Specific Gravity 2-1-2-2. Hardness 5-5. 648 APPENDIX. ASBESTOS. Fibrous varieties of hornblende, augite, and other minerals, rather than a peculiar species, receive this name. The fibres run across veins of the substance. SCHORL. Crystallized in striated prisms with quartz in the " cockle" rock of Cornwall. Colour black. Specific Gravity 3*0 to 3-3. Hardness 7. CHIASTOLITE. Crystallized in four-sided prisms, (hollow in centre,) in the clay slate of Cumberland, Spain, and Ireland. Colour pale or white. Specific Gravity 3'0. Hardness 6. CHLORITE. Crystallized in pearly non-elastic laminae, composing hexagonal plates in veins, and granite; amorphous in chloritic mica schists, and clay slates. Colour usually green. Specific Gravity 2-8. Hardness l'Q-1'5. GREEN EARTH. Amorphous, pulverulent, or compact, in amygdaloidal porphyries, basalts, and wackes. TALC. Crystallized in non-elastic lamina?, composing soft masses in some granites. Amorphous and earthy, in veins, talcose schist, and primary limestone. Colour pale. Specific Gravity 2-77. Hardness 1. STEATITE. Amorphous in serpentine, granite, clay slate, and veins. GARNET. Crystallized in rhomboidal dodecahedrons, in granite, gneiss, mica schist, clay slate, primary limestone ; near trap dikes ; hi veins. Colour red, and various. Specific Gravity 3-7 to 4'0. Hardness 7, (brittle.) CARBONATE of LIME. Crystallized in veins, cavities of calcareous rocks, shells, primary limestone, and stalactites; amorphous in limestone rocks; concretionary in oolites; fibrous in certain limestones and shells ; nodular in amygdaloidal traps ; laminar in shells and corals; pulverulent in rock marls, chalk, &c. Specific Gravity 2-4 to 2-7. Hardness 3. CARBONATE of MAGNESIA. Crystallized in veins ; amorphous in certain clays ; com- bined with carbonate of lime in dolomite, magnesian limestone. Specific Gravity about 3'0. Hardness about 4-0. SULPHATE of LIME. Crystallized (selenite) in clays; fibrous, compact, pulverulent (gypsum) in clays, &c. Specific Gravity 2-3. Hardness 2'0. MURIATE of SODA. Crystallized in rock salt ; invisibly disseminated in most rocks ; in lava. Specific Gravity 2*1. Hardness 2-0. BITUMEN. Concrete or liquid in certain limestone rocks, shells, and veins ; disseminated invisibly through the mass of many shales and limestones. OXIDE ot IRON. Crystallized in octohedral and other forms, lava, syenite, hypersthene rock, and veins ; minutely disseminated in sandstones, clays, ironstones, ochre, &c. &c. Specific Gravity 4-6 to 5-2. Hardness 5'5. SULPHURET of IRON. Crystallized in clay slates, primary limestones, near trap dikes, in chalk, clays, argillaceous limestones ; in artificial products, both of aqueous and igneous origin. Specific Gravity 4-7 to 5'0. Hardness G'O to 6'5. GLOSSARY. GEOLOGISTS employ as if they were English, or at least anglicized, many words derived from Greek, Latin, Italian, French, German, and Swedish, such as pyrogenous, stratified, brecciated, terrain, grauwack^ (greywacke), trap. Other words, previously accepted in English composition, are employed by geology in a sense more or less technical or limited. In the glossary which follows, a considerable number of such terms is included, though often borrowed from physical, chemical, zoological, and botanical nomen- clature. Another class of words, familiarly employed in classification, retaining more or less accurately the Greek or Latin form, and amounting to many thousands, is noticed in this glossary, but only so far as they indicate classes, orders, and remarkable groups of mineral and organic bodies. To pass beyond this limit, would be to write several additional treatises. In perusing any glossary, having such objects, the reader may be reminded that in adapting Greek words to the English ear and eye, the practice even of scholars has not always been uniform. A frequent source of embarrassment is found in the pronunciation of words containing the English - weapon, (n^iov animal. ANTHRACITE. Coal consisting almost wholly of carbon. v9- <* carbon. ANTHRACOTHERIUM. A fossil pachy- dermatous animal, found in lignitic tertiaries. av9-K% carbon, f-/iuv animal. ANTICLINAL. With slopes in opposite directions from an axis, avn against, xXivu to incline. APTERA. A wingless class of insects, a and TT^y wing. ARENACEOUS Strata composed of grains like sand. Arena, sand. ARGILLACEOUS. Composed of clay, or containing a notable proportion of "clay. Argilla, clay. GLOSSARY. 651 ARTICULATA. One of the four great divisions of the animal kingdom, includ- ing invertebrata with jointed bodies. ASTEROIDEA. Star fishes. An order of echinodermata, with one opening to the alimentary canal and radiating struc- ture, armt star, itio; form. ATOM. An elementary constituent of matter, incapable of further division. . priv., -riftva to cut. AUGITB. A mineral very frequent in volcanic lava and ashes, and in basaltic rocks of all ages, also called pyroxene. It is much allied to hornblende, uuyn brightness. Axis. The line about which objects are symmetrical, along which they are bent, or around which they turn. Azoic (Mur.) The lowest strata devoid of traces of life, a priv., 2>j life. BACK. Miners' term for joint. BASALT. A frequent rock of igneous ori- gin, in which prismatic structure is common, the prisms sometimes jointed. The term is borrowed from the Basalte? of Pliny. BASIN. A concave surface of strata ; a mass of strata depressed in the centre, or along an axis, by mutual inclination, not by fracture. BATHYMETRY. Measure of depth in the sea. $6os depth, ^ET^OV measure. E. Forbes has investigated the bathyme- trical distribution of mollusca in the BELEMNITE. The straight shell of a fos- sil cephalopod ; the anterior part cham- bered, the retral part fibrous, and usu- ally pointed. It was internal. /2s- Ai^vflv dart, vulgo ' thunderbolt.' BITUMEN. Mineral pitch. Many coals are said to be ' bituminous.' This is not correct : they yield bitumen on being heated, the substance is in fact produced from them by distillation. BORD. A miner's term for the face of coal parallel to the natural fissures. Contrasted with end. BOULDER. A large mass of rock, trans- ported by some unusual natural means from a distant situation. BRACK IOPODA. A class or order of ace- phalous mollusca, including equivalved and inequivalved groups, with spiral organs on each side of the mouth. (2>ee,%iav arm, vrov; foot. BRACHYURA. A division of decapod Crustacea with short tails. /; short. OV^K tail. BRANCHI/E. The breathing organs of animals which respire the air contained in water. BRANCHIOPODA. A division of Crustacea, whose breathing organs are at the base of the organs of motion. Pget>y%itx. gills, vov$ a foot. BRECCIA. Rock composed of unworn fragments cemented together. The word is Italian, and is matched by the Cumbrian term ' Brockram.' BRYOZOA. A portion of the delicate pro- ductions of the sea once regarded as zoophytes, and now ranked among compound mollusca, receives this name. P>vov moss, & animals. BUNTER. A German term for the new red sandstone. CAINOZOIC. The upper division of strata holding recent forms of life, xuivos recent, j life. CALCAIRE GROSSIER. The name of one of the most important of the Eocene tertiaries of France. It signifies coarse limestone. CALCAREOUS. Of the nature of limestone. CALLIARD. Local name for hard stone or pebble. #aX/; pebble, caillou, Fr., and sometimes galliard. CANK. Bad, irregular, hard stone. CARBON. The chemical element of the solid parts of plants, and of coal which is derived from plants, obtained by them from the carbonic acid of the at- mosphere. CARBONIC ACID. One of the constituents of the atmosphere the aerial food of plants. In rain, spring water, and rivers, it is an important agent of che- mical changes. CARBONIFEROUS. Specially j-ielding coal. CATACLYSM. A violent flood, deluge. xzraxXiJirf&o; inundation. CATHEAD. A septarium is so called in the north of England. CELLULOSES. That part of the vegetable world which consists only of a cellular structure, as true sea-weeds, contrasted with Vasculosa, as a tree. 652 GLOSSARY. CEPHALA. A great division of mollusca with distinct head. *npaX>j head. CEPHALOPODA. The most highly organ- ized class of mollusca, with remarkable tentacles round the mouth. The poly- pus of Homer and Aristotle is an ex- ample, now known as the cuttle fish. xiQaXv head, #ovj foot. CETACEA. Swimming mammalia, ana- logous to dolphins and whales, xnrog whale. The term is in Homer, but not with the limited meaning now as- signed. CHALK. Properly, a soft white limestone. It is not equivalent to the Latin cafo, or the German kalk, but rather to the Latin creta and German kreide. CHERT. A peculiar flinty stone, more or less granular or cellular, occurring in many limestones. CHLORITE. A mineral often formed in thin plates like mica, and of a greenish hue, whence the name, ^Xo^a; green. ClRRIPEDA, ClRRIPEDIA. Curl-footed ; cirrus a whorl, and pes foot. A class of articulated animals. CLAYSTONE = Compact felspar. CLASS. A principal group of objects in natural history, as Mammalia. It in- cludes orders, families, genera, species, and varieties. CLEAT. A system of fine parallel fissures in coal, crossing the strata in one direc- tion. A kind of cleavage=leat, nearly =bate. CLEAVAGE. A fissile structure not coin- cident with original lamination, an ex- ample of metamorphism. CLINKSTONE. A felspathic igneous rock, which on account of its compactness, is resonant when struck. CLOUGH. A precipitous rocky glen or steep cliff. COAL. A mass of plants, greatly com- pressed, and chemically changed, by slow internal decomposition. Accord- ing to the degree of change, and the loss of oxygen and hydrogen, the pro- duct becomes peat, lignite, jet, caking coal, steam coal, stone coal, anthra- cite. COLEOPTERA. An order of sheath- winged insects, including 'Beetles.' xoXio? sheath or case, vffrci%.Xos ice. CRYSTALLINE. Confusedly crystallized. CRYSTALLIZED. Having the structure of a crystal. CUTTER = Back = Sline. CYCADE^E. A group of gymnosperm vascular plants, with stems marked in quincunx by the bases of pinnate leaves. Fruit, a cone. CYPERACE^E. Plants like cyperus, sedges. DEBACLE. A local deluge or cataclysm. DELTA. The flat land formed at the mouth of a river, such as that of the Nile described under this name by Herodotus, sometimes triangular in shape, or like the Greek letter A. DELUGE = Cataclysm. DENSITY. The quantity or weight of matter which exists in a given space. In some bodies it is proportioned to pressure. Not = specific gravity. DENUDATION. The process by which flowing water has removed masses of rocks, and thus uncovered other rocks. DEOXIDIZED. Deprived of oxygen. DESICCATION. The art of drying. DETRITUS. What is removed by natural agencies from the exposed surfaces of rocks. DIABASE = DIORITE. Plutonic rocks, greenstones, composed of hornblende and felspar. DIALLAGE. A variable mineral composed of silica, united with magnesia and other bases. Enters into the composi- tion of diallage rock, (gabbro) and serpentine. DICOTYLEDONOUS. A large division of the vegetable world ; with distinct repro- ductive organs ; wood (if any) in con- centric layers; leaves with divided nervures; seed with two lobes or cotyledons. $is twice, xorvhrdat seed- lobe = Exogens. DIDELPHYS. A marsupial quadruped, "big double, SiXQu; uterus. DIKE. A mass of igneous rock, often found traversing other rocks, and some- tunes projecting from them, so as to resemble a wall. /*,- = dig, Gael, a wall, fence, or division. DILUVIUM. The earthy matter accumu- lated by a deluge. DINOSAURIA. = DEINOSAURIA. $vo? monstrous, eav^a, lizard. DIP. The inclination of any stratum, dike, or mineral vein, from a horizontal plane, is expressed by this term. In the case of mineral veins = ' hade,' ' under- lay' from the vertical. (See STRIKE). DIPTERA Insects with only two wings, in the perfect state. Sis twice, vrr^ov wing. DISTRIBUTION (OF ORGANIC FORMS). E. Forbes treats of this subject under three heads geological, or in time geographical, or in space and bathy- metrical, or in depth. DOLERITE. An igneous rock composed of felspar and augite. DOLOMITE. A crystallized rock contain- ing carbonate of lime and carbonate of magnesia, often in simple atomic pro- portion. DUNE. A sandhill. (Brit.) ECHINOIDEA. Sea urchins, an order of the class echinodermata. t%ws urchin, iitits form. ECHINODERMATA. A large class of radi- ated invertebrate animals; with firm often crustaceous integument. t%ivos urchin, and Si^a skin. ELVAN. Cornish name for a felspathic rock, occurring in dikes, in the mining districts = Eurite. ELYTRA. Wing cases of beetles. iXvrgov a sheath. ENALIOSAURIA. Sea lizards. A fossil group of reptiles including ichthyo- saurus and plesiosaurus. tv/uj marine, ffav^ae. lizard. END. A miner's term for the face of coal, transverse to the natural fissures. ENDOGENS.' A division of the vegetable world, with distinct reproductive organs, wood in separate bundles, not in con- centric layers, leaves mostly with sim- ple nervures, seed with one cotyledon. ivbov within, yivopui to be formed = monocotyledonous. ENTOMOSTRACA. A large division of Crustacea contrasted with Malacostraca. Literally, shelled insects, ivropoi in- sect, osr^xxtv shell. The name was first used by Muller. 654 GLOSSARY. EOCENE. The lowest great division of the tertiary strata in which the dawn of recent life appears (Lyell.) tjus the dawn, xaivo; recent. EOLIAN. Nelson gives this name to loose materials drifted and arranged by the wind. EPOCH. The point of time when any event happened. i#o%rj. ERA = Period. EREMACAUSIS. Slow chemical change. r^'.fta, slowly, Kctua-ts burning. ESTUARY DEPOSITS. Such are often dis- tinguishable from truly marine and truly fresh water strata. EURITE = Whitestone = Elvan. EXOGENS. A division of the vegetable world contrasted with Endogens=dico- tyledonous. igw outside, yino/tai to be formed. FALSE BEDDING = Oblique stratification. FALUNS. The shelly beds of Touraine. FAMILY. Term used in natural history to include some allied genera. FAULT. A fissure, on one side of which the rocks have been displaced with re- ference to the other side. The elevation or depression of one side compared to the other may be an inch, foot, 1,000 feet or more. FAUNA. The animals now or formerly natives in a given tract of land or sea. FELSPAR. A genus or family of minerals in crystallization, once regarded as a single species, in which silica is com- bined with various bases. Literally rockspar. FERRUGINOUS. Obviously containing oxide of iron. FIRECLAY. Clay which bears a great . heat without cracking or melting ; often found under beds of coal. FIRESTONE. Stone which bears moderate heat without injury usually sandy. FLAGSTONE. Laminated and fissile stone. FLORA. The plants now or formerly natives in a given tract of land or sea. FLOTZ. The secondary strata were termed flotz or flat-lying by Werner and other German writers. FORAMINIFERA. A class of minute cham- bered shells, with an orifice in the plates which separate the chambers. Foramen, a small opening. FORMATION. A group of rocks, associated by geological position, by immediate succession of time, and by organic or mineral affinities. FOSSIL. Literally, what is dug out, and thus Fossilogy = Orycterology. Tech- nically, often limited to organic remains of ancient life, and thus = Palceonto- lo gy- FREESTONE. Stone which admits of being freely cut and shaped ; not marked by particular lamination. GANISTER. Local name of a hard fine grained grit, under a certain coal bed, or a few coal beds in the north of Eng- land. GARNET. A genus or family of minerals in rhomboidal crystallization, composed of silica united with various bases. GASTEROPODA. A class of mollusca in which the head is developed, and mo- tion is accomplished by means of a muscular foot attached to the lower side of the body. yasm belly, vovg foot. GAULT. An argillaceous member of the cretaceous system, separating the upper and lower green sands. GEBILDE = German = Terrain = Forma- tion. GENUS. A group of allied species. GEOLOGY. Derived from >yn earth, and Xayaj doctrine. GLACIER, Fr., = Gletscher, German. The peculiar ice which moves downward from snowy mountains. GNEISS. A German miner's term for the oldest group of granitoid strata. GRANITE. Literally, grain-stone, com- posed of distinct quartz, felspar, and mica. Sometimes the mica fails, or is partially replaced by hornblende, the rock then passes to syenite. GREENSTONE. An igneous rock com- posed of felspar and hornblende. GBEYWACKE = GRADWACKE. A term once common, now grown obsolete, employed by German miners to de- signate argillo-arenaceous primary strata. GRIT. A term of the northern countries for any hard arenaceous rocks. Nearly = sandstone as used in the south of England. GLOSSARY. 655 GROUP. An assemblage of any allied elements, GYMNOSPEKMS (Brong.) Flowering plants with naked seeds ; the wood in con- centric layers, yupvo? naked, o-vrigpa seed = gymnogens. GYPSUM. Sulphate of lime. The Greek original yv-^o; seems to apply also to chalk. 7j earth, tyu to boil. GYROGONITES. The spiral seed vessels of plants (Characeae) found in fresh water strata, yv^s round, yovo; seed. HEMATITE. Red oxide of iron. HAZLE. A hard, often cherty, gritstone; probably borrowed by the Northum- brians from the German Kiesel flint. HEMIPTERA. An order of insects whose outer Avings are half coriaceous, fiftiffu half, water, and yivepat to be formed. HYDROPHYTES. Plants which grow under water. vbu( water, Qurov plant. HYPOGEKE (Lyell.) This term was pro- posed as a substitute for primary, to mark their formation or transformation from below, l-xo below, y*yquj to be formed. HYPOZOIC. A term proposed in the former edition of this work for the low- est primary strata, such as gneiss, mica, schist, &c., found below all those which contain organic remains. vt!o; straight, xXctfis fracture. ORDER. The first subdivision of a class in natural history. OUTLIERS. Farts of any stratum which lie detached and separated from the main body, usually the effect of denu- dation. OXYGEN. One of the constituents of ah-, water, and most rocks and minerals 'vital air.' Literally, source of sharp- ness or acidity. o%vg sharp, and ytv for origin. PACHYDERMATA. An order of mammalia frequent in tertiary strata. Includes elephant, rhinoceros, mastodon, &c. jftt^vg thick, SigftK skin. PALEONTOLOGY. Zoology and botany, applied to the ancient forms of life pre- served on the earth. vaXaiot ancient, uv-ovros being, Xoyos doctrine. FAL^EOTHERIUM. An extinct pachyderm from the Eocene tertiaries. vraXaios ancient, fayiov animal. PALEOZOIC. The lowest of three grand divisions of strata, including the most ancient forms of life. a-aXa^j ancient, life. PEGMATITE. Binary granite containing only quartz and felspar. PELAGIAN. Formed in deep sea, as dis- tinct from littoral, and estuary. PELOROSAUR. The great reptile of the Wealden. vr&uoos gigantic, troivptx, lizard. 2 PERIOD. The measure of time which has elapsed between two events = duration. PEROXIDE. The full degree of oxidation. PETRIFACTION. Conversion to stone. The term is not confined to fossils. PHENOMENA. Things appearing. Facts observed frequently. PHANEROGAMIA. Flowering plants with distinct reproductive organs. Qxvigos apparent, yttpiu to marry. PHASCOLOTHERIUM. A marsupial qua- druped from the oolite, (fettrxu^o; bag, Gnotov animal. PHCENOOAMIC = Phanerogamic. PHONOLITE = Clinkstone. PHYSICAL SCIENCE. The knowledge of nature, the branches of human study intended to augment this knowledge. u,yu to eat. ZOOPHYTA. Plant -like animals, A great division of invertebrata, the fourth and lowest division of the animal king- dom. aev animal, f VTOV plant. INDEX. [For Index of Authors, seep. 668.] Abberley Hills, 514. Adriatic., formation of deposits in the, 485. Agriculture, intimate knowledge of various soils produced by, 6. Alps, elevation of the, 524. America, stratification of, 100. Amygdaloidal Trap, 525, 526. Analogy between fossils and strata of the same age, 67, 68. Andes and Cordilleras, characteristic fea- _ tures of the, 100. Animal population, analogy between past and present species of, 432. during the Pleistocene period, 432. lived in countries where their bones are found, 433. Animal remains compared with living spe- cies, 62. Apennines, stratification of the, 517. Aqueous action, periods of, 420, 421. Ardennes, origin of their formation, 224. Arran described, 503. geographical features of, 404 to 406. Arthur's Seat, 528. Ashburnham beds, 315. Atmosphere, wasting effects of the, on rocks, stones, &c., 468 to 473. effects of a cooling globe upon the, 612. mean temperature of the, described, 637. Atoms, Epicurean doctrine of, 3. Avalanche, described, 475. view of the track of an, 474. Bagshot Sand, 387. Bafa Group, 115. Balkan, view of, 469. Barometer, examples for the use of the, 639, 640. Barton Clay Groups, 388. Basalt, composition of, 519. districts of, 521, 522. Basaltic Dikes, 521. Beds or Strata, alternation of, 48. divided, 28. gradation of, 49. laminated, 29. thickness, variation of, 28. Belemnite, (5. Listeri), 12. Bembridge Beds, 389. Ben Nevis, described, 511 to 528. Bohemian Basin, 103. Boue on the action of heat along the Py- renean chain, 98. Bourbon, view of, 559. Bramerton Pit, section of, 404. Brill Hill, 313. British Strata, series of, 30. Brongniart on Coal deposits, 211, 215. on extinct flora and modern vegetation, 57, 58. Brora, section of, by Murchison, 299. Caer Caradoc, 528. Cainozoic Strata compared with the prece- ding Series, 380, 381. tabular view of, 31. Calcaire grossier, 360. Caldron Snout, view of, 164. Calton Hill, Edinburgh, 526, 528. Cambrian Fossils, figures of, 129. Caradoc beds, 116. Carboniferous epoch, subterranean expan- sion during the, 587. Carboniferous Fossils, figures of, 234 to 244. Carboniferous Limestone, 159. dislocated, 161. sections of, in the Northern dales com- pared, 165. Carboniferous System, comparison between the various groups of the, 233. convulsive movements in the, 221. groups of the, 157. of England, 159. of England and Wales, 158. of Foreign countries, 208. of Ireland, 206. of Scotland, 202. organic remains in the, 226 to 232. range of the, 207, 208. Castle Hill, Edinburgh, 519. Central France, description of Strata in, 99. Cephalopoda, recent and fossil species com- pared, 60. Chalk, origin of the formation, 358. 662 INDEX. Chalk Marl described, 357. Charpentier on the alternations of Gniess and Granite, 98. Chemical metamorphism of rocks, 605. Chert, beds of, 308. beds and nodules of, 172, 177. Claystone Porphyry, 525. Cleat, described, 604. Cleavage, defined, 43, 45. of Rocks, 43. of Slate, 44, 111, 112. Coal Basin of Flintshire, 195. Coal Beds, average thickness of, 188. by Lake deposits, 213. by River deposits, 214. by Vegetable deposits, 212, 213. by periodical inundations, 215. how deposited, 211. Coal, characteristic features of, 180. composition of, 54. districts of, 181. effects of internal heat upon the formation of, 626. formation of, 169, 215, 217, 218. Coal Fields, American, 210. Central, 191. Cheshire and Lancashire, 189. Coalbrook Dale, 196. Cumberland, 195. Germany, 209. Great Northern, 190. India, 209. Midlothian, 202 to 204. North Staffordshire, 194. Russia, 209. South Staffordshire, 192. Spain, 208. Yorkshire, compared with other British and Foreign coal fields, 187 to 189. Coal series, described, 204, 205. Lower or Ganister, 182 to 184. Middle, 186. Upper, 187. Conchifera, fossil and recent, 59. Conglomerates, where most abundant, 66. Conical boulders, Arran, 614. Conical deposits, formation of, 567. Continents, elevation of, 38. Continuity of Strata, described, 22. tabular view of, 23. Contorted Strata, 34, Contraction, inequalities of the earth's sur- face caused by, 599. Convulsions, direction of, 575. duration of, 569, effect of, on land and water, 579. effect of, on deposition of strata and or- ganic life, 590. epochs of, 569. geological periods of, 565. indications of, 568. Convulsions, on the continents and islands of Europe, 574. relation of igneous rocks to, 602. tabular view of, in Britain, 573. Coral, formation of, 55, 56. islands described, 491. Coralline Oolites, districts of, 309, 310. Cornbrash, formation of the, described, 295. districts of, 295 to 302. Cornwall, range of Lower Paleozoic Strata in, 117. peculiar character of granite veins in, 509, 510. Cosmogony, 2, 466, 467. Cretaceous system, dislocations of the, 362, 363. range of the, 359 to 361. Crust of the earth, formation of, 612. successive conditions of the materials, 630, 631. Crystalline limestone, alternation of with other rocks, 85. described, 84. minerals in, 86. Culver Cliff, 359. Cumbrian rocks, classification of, 101. general section of, 103. Cumbrian Slate districts, 107. De Beaumont, on Oolitic disturbances, 323. systems of elevation by, 574. De la Beche on Old Red. Sandstone forma- tion, 142. Deltas, formation of, 479, 484. of the Ganges, 487. of the Nile, 488. De Luc, on coal deposits, 215. Deposits, chemical, 49. lacustrine, 484. mechanical, 50, 619. nature of, in gulfs and estuaries, 485. of the foreign tertiary system, 446. superficial, 616. vital, 50. Deshayes, investigation of fossil remains by, 69. Detrital deposits, of the Cumbrian moun- tains, 421, 422. of other localities, 423 to 427. Devil's arrows, 472. Devonian strata, districts of, 145. Diallage rock, 516. Dirt bed of Portland, 313. Distant deposits, analogy between, 24. Disturbed strata, 33. Drumadoon, view of, 505. Earth, mean density of the, 14. elementary substances in the, defined, 18. specific gravity of materials in the, 15. spheroidal figure of the, how formed, 15. INDEX. 663 Earthquakes, cause of, 560, 562. velocity of, 561. Earth's axis, displacement of the, 627. Earthy compounds, 16. Eocene deposits, 385. Epilimnic groups, described, 451. Estuaries, nature of deposits in, 485, 618. Estuary accumulation, described, 618. Extinct flora and modern vegetation, 57, 58. Faluns of Touraine, described, 452. Faults in strata, 570. Felspar, analysis of, 498. described, 497. Felspar porphyry described, 511, 512. Ffclspathic rocks, atmospheric influence upon, 469. Fingal's Cave, view of, 523. Fire Clay, 211. Fissures in Rocks, 41, 42. Flint nodules in chalk, 358, 359. Floetz rocks, 8. Fossils, differ in strata of a different age, 67. formation of, 51. identical in rocks of same age, 68. petrification of, 52. Fossil plants, formation of, 53. Fossil species, British, 61. compared with recent species, 63. distribution of, 3. European, 61. in various rocks, 62. number of, 57. Fossil flora, physical cause of its luxuri- ance ? (temperature of the period) 214. of Great Britain, 218. Fossil tribes, successive eras of, 64. Fractured flints in chalk, cause of, 351. Gale Force, view of, 176. Gasteropoda, recent and fossil species com- pared, 60. Gault, or Golt, analogous to the Lower Green Sand, 356. Gault Fossils, figures of, 379. Geology, objects of, 1, 620. defined, 2. inductive, 4. speculative, 2. Geological changes, comparative table, 624. Geological chronology, 616. object of, 620. Geological inquiry, limitation of, 625. Giant's Causewav, view of, 521. basaltic formation of cliffs near the, 520. Glacial deposits, 419. origin and use of the term, 420. theory of, 428, 429. Glaciers, formation of, 474. Glen Coe, 511, 528. Glen Tilt, section of, 509. Globe, physical relations of, as a part of the solar system, 635. temperature of the, 636. Gneiss, described, 82 to 84. alternation of with other rocks, 83, 84. in England, 89. in Scotland, 90. minerals contained in, 83. rocks associated with, 81. stratification of, 83. Gneiss and Mica Slate and Clay Slate inversely proportional to each other, 106. Goat Fell, view of, 504. Gordale Scar, view of, 166. Gosau beds described, 455. age of, 456. groups of, 456. Gradations of deposits and of fossils coin- cident, 71. Granite, analysis of, 17. rocks allied to, 495. peculiar character of, 496. veins of, 497, 499 to 508. crystallization of, 499. minerals embedded in, 500. elementary composition of, 501. antiquity of, 507. Granitic rocks, minerals contained in, 19. Gravel deposits, districts of, 427. Green middle slates, 108. Greenstone, composition of, 517, 518. Guadaloupe, view of, 557. Gulfs and Estuaries, deposits in, 485. Headon Hill fresh water group, 388. Heat, effect of in early geological periods, 262. decreasing effect of, in newer strata, 607. effect of, on stratified rocks, 601. interior effect of, on the outward surface of the Earth, 609. rocks produced by the agency of, 493. theory of, 599. Helm Crag and Grasmere, view of, 109. Hempstead Beds, 389. High Force, Teesdale, view of, 164. History of the formation of coal, 218 to 221. Honiston Crag and Buttermere, view of, 112. Horizontal strata, 33. Hornblende, described, 513. Hornblende Slate in Scotland, 94. Horsham beds, 317. Hypozoic strata, 80. enumerated, 81. tabular view of, 32. Ingleborough and Penyghent, section of, 161, 162. Igneous action, local centres of, 551. 664 INDEX. Igneous rocks, general basis of, 260. in the Lake districts, 112. production of by various causes, 494, 495. Inductive geology, origin of, 4. what principally founded upon. 10. Inundations, effects of, 474. Ireland, north and south of, described, 96. range of Lower Palaeozoic in, 118. Irish Elk, skeleton of, 441. Isle of Wight, dislocation of, 389. tertiaries of the, compared with those of foreign localities, 453. Joints in rocks, 40, 41. Jukes's classification of the South Stafford- shire Coal Fields, 193. Katakekaumene district, 4, 557. Kelloway Rock, described, 36. fossils in, 70. Killas, described, 117, 510. Kimmeridge Clay, 22. range of; 310, 311. Kinnoul, hill of, described, 525, 526. Kirkdale Cave, ossiferous remains in, 414. Kuhloch Cave, ossiferous remains in, 415. Lacustrine tertiary deposits, 459. organic remains in the, 459, 460. Lagan Hill, Arran, view of, 494. Land, gradual elevation of, 584. mean temperature of, described, 636. Langdale Pikes, view of, 110. Lead Ore obtained from Limestone beds, 546, 547. Lias, range of, 284. Cottswold, 287. detailed sections of, 288, 289. France, 290. Germany, 290. Midland counties. 287. North Britain, 290. Switzerland, 291. in Yorkshire, 285. Lignite, or Wood Coal, described, 461. of Bovey Tracey, 462. of the Meisner, tabular section of, 463. Limestone, chemical deposit of, 620. oceanic deposit of, 65. origin of, 632. Limestone Shale, described, 174. localities of, 174, 175. Lister, cited on Palaeontology, 12. London clay, thickness of, 386. physical features of, 387. Lower calc grit, district of, 307. Lower green sand, described, 352. detailed section of the various groups, 354, 355. localities of, 353. Lower Mesozoic strata described, 263. Lower Palaeozoic strata, classification of, by Sedgwick, 101. disturbances during accumulation, and after Silurian deposits, 119. range of, 107. table of organic remains of the, 121, 122. zones of the, defined, 104. Ludlow group, range of, 116. Magnesia, cause of its prevalence, 255. Malvern Hills, described, 513 to 515. Mammalia in caverns and superficial de- posits, 442 to 443. in preglacial deposits, 431, 432. Man, geological monuments of the exis- tence of, 436. period of, in Britain, 383. Marine fossils, comparative table of. 59. Marine animals, successive races of,' 593. distribution of, 67. Marine stratified deposits, irregularity of, 402. Marl Slates, districts of, 252. Mastodon, skeleton of, 441. Mastodontoidal races, era of, 371. Mean direction of Strata, influence of dis- turbances upon the, 120. Mechanical deposits, described, 616. Mechanical Strata, defined, 46. ingredients of, 47. Mediterranean, Osseous Breccia contained in the, 418. deposits in the, 484, 485. Megatherium, skeleton of, 440. Meiocene strata, 401. Melaphyre, 524. Melted rocks, floods of, 564. waves of, 561, 562. Mendip cave, ossiferous remains contained in, 416. Mesozoic strata, tabular view of, 31. Metamorphism of strata, ratio of the, 606. Mica schist, described, 84. alternation of with other rocks, 85. minerals contained in, 86. rocks associated with, 81. Mica slate and granite, alternation of, 97. Middle Oolite formation, described, 304. surface arrangement of, 304, 305. Middle Palaeozoic strata, physical features of the, 135. organic remains in, 146 to 150. Millgill Force, view of, 175. Millstone grit, composition of, 178. origin of, 179. Millstone grit rocks, view of, 178. Miners of Saxony, information of the, em- bodied by Agricola, 6. Minerals, embedded, 500. in various rocks, 509. number of, 18. INDEX. 665 Mineral Veins, age of, 537. described, 529. direction of, 542. general form of, 534. geographical features of, 541 to 543. how deposited, 532. intersections of, 539, 540. more numerous in Primary Strata, 120. substance of, 530. various phenomena of, 537, 538, 545. Mineral veins and trap dikes, analogy of, 37. Mississippi, deposits discharged by the, 485, 486. Mitchell, on succession of strata, 9. Modern Deposits and Causes in Action, opinions of the English school on, 466. Modern Geology, objects of, 13. Molasse, 457. Molecular metamorphism of rocks, 605. Mountains, elevation of, 37. in Africa and Asia, 79. in Europe, 78. principal line of, 79. ranges and groups of, relation between, 77. Naples, view of, 556. Natural agencies, uniformity of, 629. Neptunian rocks, 26. New Red Sandstone formation, disturbances in the, 281. Niagara, falls of, 478. recession of (estimated by Lyell), 617. Nile valley, 3. Northern dales, relative proportion of lime- stone and other deposits in the, 165. Northern region, climate during the pleis- tocene period, 433. Objects and scope of Geology, 1. Ocean level, speculations on the, 581. variation of the, 583. Old Red Sandstone, formation of, 138. Miller cited on, 138. origin of the formation in England, 138. in the Cumbrian district, 138. in Wales, 140. groups of, 141 to 144. in Ireland, 143. Rhenish and Belgian, groups of, 144. Oolitic System, range, conformation, and classification of the strata, 282. analysis of the various formations in the system, 283, 284. foreign localities of the, 318, 319. divisions of the, 320. elevation of the, 323. Oreston caves., ossiferous remains contained in the, 417. Organic remains, deposits of during the Pleistocene period, 409. gradual change in the races of, 69. Organic remains, embedded, 621. succession of various races of, 622. Origin of Gneiss and Mica Schist, 88. Ossiferous caverns, 411. circumstances connected with their forma- tion, 412, 413. Ossiferous remains, Pleistocene period, 410. Oxford clay, described, 306. Palaeontology, progress of, in England, 11. tabular view of the successive stages of, 623. Palseotherian or lower fresh water group, deposits of the, 480. Palaeotherian races, era of, 381. Palaeozoic Strata, tabular view of, 32. Paris basin, 459. Peak of Derbyshire, 40. Peat bogs, 212. Pennine chain, disturbances in the, 223. section of the, 161. variety of strata in the, 176, 177. Permian strata, classification of, 245, 246. collective character of, 247. range of in England, 248 to 250. range of in Europe, 251. Permian system, described, 245. Cumbrian districts of the, 248. in England, 252 to 255. in Ireland, 250. in the Midland counties, 249. in the south of England, 250. organic remains of the, 255 to 257. section of in Yorkshire, 246. Petrification, described, 11, 64, 55. Pitchstone, 527. Plants, number of various species, 57. recent and fossil species compared, 58. Plastic clay groups and Thanet sands, thickness of, 385, 386. Pleiocene strata, formation of, 402. list of organic remains in the, 404 to 406. Pleistocene British Fossils, genera of, 439 t to 440. Pleistocene deposits, periods of, 408. Plutonic rocks, age of, 502. defined, 26. formation of, 502. general basis of, 72, 73. Poikilitic group, list of organic remains of, Poikilitic series described, 263 to 265. Porphyritic breccia, 528. Portland oolite, 311. section of the beds, 312. Postglacial deposits, 430. mammalia in, 432. Precarboniferous ages, state of the atmo- sphere during the, 613. Primary limestone, second range of, 95. 666 INDEX. Primary strata, changes in, 606. earliest cause of formation, 75. general conclusions admitted as to the formation of, 76. how distinguished, 74. influence of heat upon, 260, 606, 607. Primitive rocks, defined, 8. Principal rocks, described, 81. Purbeck beds, described by Webster, 315. fossils contained in, 315, 316. Pyrites in chalk, 359. Pyrogenous rocks, comparison between ancient and modern, 496. geographical relation of, 507. relative age of, 502. Quartz rock, described, 86. in Scotland, 93. Rain channels, 473. Bed rock, 109. minerals of, 110. Red Sandstone, described, 136. Refrigeration, effect of, on the contraction of the earth's crust, 626. Remains of Terrestrial Animals and Plants, not proportionate to existing species, 71. Rivers, accumulation of Materials trans- ported by, 480, 481. bars at the mouths of, 486. deposits formed by, 478. effects produced by traversing lakes, 482. Rocks, classification of, 7. direction of fissures in, 42. general cause of joints and fissures in, 40, 41, 603. internal arrangement of, 20. internal structure of, 40. surface arrangement of, 19. Rocks and Veins, connection between, 543 to 545, 551. Saliferous System, origin of the, 267. organic remains of the, 275 to 278. range of the, 268. table of organic remains of the, 275 to 278. various circumstances attending the formation of the, 271, 272. Salisbury Crag, described, 517, 518. Salt and gypsum, layers of, 272, 273. Salt Beds, described, 267. of Cheshire, 268. of foreign localities, 269. Sandstone, Shale, &c., littoral deposits of, 65, 66. Scale Force, view of, 113. Scar Limestone, described, 171, 172. general aspect of, 170, 171. localities of, 166 to 168. subdivision of, 197. Secondary strata, tabular view of, 31. Sea, erosive and transporting action of, 489,490. Sedimentary deposits, 591. Serpentine, in Scotland, 94. stratification of, 516. Shells, formation of, 55, 56. of the crag, 402, 403. recent and fossil species compared, 59. Sicilian deposits, 458. Silurian and Cambrian rocks, comparative table of, 1 03. groups of, 105. Hall's classification of, 105. Skiddaw, section and view of, 107. Skye, physical features of, 516. Slate, districts of, classed, 101, 102. Collyweston and Stonesfield, detailed section of, 301, 302. general section of, 103. Snowdon, section of, 114. view of, 115. South of England, dislocations of tertiary strata in the, 445. Springs in rocks, 637. Steam, pressure of. on volcanic action, de- scribed, 558. ' Strata, continuity of, 22. comparative table of, 30. contorted, 34. convulsion of, 36, 38. definition of the term, 27. dislocation of, 34. divided beds of, 28. division of, by master joints, 43. effects of heat upon the deposition of, 608. elevation of, 513. lamination of, 28. series of, in Sweden, 6. thickness of, 28. Stratification, tabular view of the succes- sive stages of, 623. Stratified deposits, 618. Streams, erosion by, 476. transporting power of, 478. Structural metamorphism of rocks, 602. Subappennine deposits, described, 457. Subterranean expansion, 685. before the Oolitic epoch, 589. before the Saliferous period, 588. Subterranean heat, fluctuation of, 638. Succession of races, described, 622. diagram of various changes in the, 624. Succession of rocks, knowledge of obtained by mining, 5. Succession of strata, described, 9, 10. Succession of tertiary strata in Britain, 383, 384. Swaledale, section of, 162. Swallow Holes in Limestone, 173. Syenite, composition of, 513. hypersthenic, 515. INDEX. 667 Talcose Slate in Scotland, 93. Teesdale and Aldstone Moor, section of, by Forster, 163. Terrestrial and Marine Fossils not usually abundant together, 64. Terrestrial organic life, origin of, 628. Tertiaries of the Isle of Wight compared with those of Foreign localities, 453. Tertiary deposits, formation of, round pre- viously elevated islands, 382. Tertiary Sea of Europe, extent of, 447. its relation to existing seas, 448. Tertiary strata, tabular view of the succes- sion in Britain, 383, 384. of France and Germany, 454, 455. in Europe, 382. Thermometrical scales, 638. Tilgate beds, division of, 316. Tornidneon, section of, 508. Transition rocks, defined, 8. Trap Tuff, 528. Tufa, formation of, 458. Unstratified rocks, defined, 25. Upper Calc Grit, 310. Upper Chalk, 358. Upper fresh water groups, deposits in, 451. Upper Green Sand Fossils, 379. Upper Magnesian Limestone, described, 254. Upper marine groups, deposits of the, 481. Upper Mesozoic Fossils, lists of, 364 to 372. Upper Mountain Limestone Belt, described, 177. Upper Oolite Formation, described, 310. Veins, age of, 7. granite, 509. mineral, 529. Vertebral remains, 57. Vertical strata, 33. Volcanic action in different districts, 59 4, 595. Water, chemical agency of, 46. mean temperature of, 636. mechanical agency of, 47. Weald, elevation of the, described, 598. Hopkins's theory, 597. Lyell's propositions, 594 to 597. Wealden formation, extent of, 618. Wensleydale and Yoredale rocks, section of, 162. Wernerian theory, 6. White marbles of lona, 95. Yellow Magnesian Limestone, 253. organic remains found in, 254. Yorkshire, formation of cliffs on the coast of, 21. coal fields of, compared with other British and Foreign coal fields, 187. Yorkshire Flagstone, atmospheric influence upon, 470, 471. Zones, Upper and Lower, definition of, 104. Zoophytes, where found, 51. recent and fossil species compared, 59. INDEX OF AUTHORS QUOTED OE NAMED. Adams, 434. Agricola, 6. Aristotle, 3. Bacon, 4. Barrande, 102. Beechey, 435, 492. Bennett, Miss, 312. Berger, 96, 519. Beudant, 209. Bigsby, Dr., 427. Binfield, 317. Boase, Dr., 512, 519, 543. Bou6, 90, 93, 94, 98, 136, 137, 436, 455. Bowman, 218. Breislac, 225. Brodie, 52, 289. Brongniart, 57, 58, 61, 86, 212, 215, 412, 426, 448, 450, 452, 454, 457, 458, 463, 517, 526, 613, 614. Bruckner, 426. Buckland, 218, 246, 307, 385, 411, 414, 415, 416, 419, 427, 431, 512, 519, 595, 628. Calcott, 416. Charlesworth, 32, 383, 402. Charpentier, 84, 98. Conybeare, 74, 157, 181, 191, 192, 200, 224, 246, 287, 290, 416, 512, 519. Cordas, 6. Corder, 99. Craig, 204. Cronstedt, 6. Cuvier, 10, 13, 33, 383, 411, 418, 419, 431, 433, 448, 450, 452, 616, 628. Dalman, 61. Danbeny, Dr., 458, 498, 555, 613. Davy, Sir H., 117. Dawson, 560. De Beaumont, 80, 120, 269, 270. 323, 363, 462, 524, 574, 575, 628. De la Beche, 102, 142, 169, 170, 199, 200, 250, 288, 313, 315, 320, 361, 510, 545. De Luc, 211, 215, 616. Denny, 410. De Serres, 460. Deshayes, 61, 70, 456, 457. Desnoyers, 99, 290, 438, 452. De Verneuil, 105. D'Halloy, Omalius, 181, 432. Dikes, 353. D'Orbigny, 146, 452, 622, 623. Dufrenoy, 98, 99, 551. Egertpn, Sir Philip, 175, 273. Enceliiis, 6. Enniskillen, Lord, 175. Epicurus, 3. Eratosthenes, 3. Eschwege, 86. Fairbairn, 558. Farey, 174, 202. Fitton, 487. Forbes, 315, 316, 383, 389, 453, 638. Forchhammer, 255. Forster, 163. Fox, 558. Fracastorio, 11. Freisleben, 181. Galileo, 4. Gesner, 6. Goldfuss, 61. Greenock, Lord, 519. Greenough, 209, 292, 627. Griffiths, 143, 180, 206, 207, 208. Hall, James, 105, 117, 146. Hamilton, 4, 557. Hawkins, 536. Hawkshaw, 218. Heer, Prof., 461. Henry, 225. Henslow, 96, 102, 118. Herndeshagen, 462. Herodotus, 3, 488. Heywood, 189. Hibbert, 93, 202, 203, 218. Hitchcock, 210, 425, 429. Hoffman, 181. Holland, 266, 267. Hopkins, 558, 565, 576, 597, 612. Horner, 435, 513, " 514. INDEX. 669 Humboldt, 100, 560. Button, 466, 517, 628. Jager, 291. Jameson, Prof., 525. Jardine, Sir W., 273. Johnston, Prof., 54, 255. Jones, 258. Jukes, 193, 194, 207. Kentmann, 6. Kepler, 4. Kidd, 500. King, 251, 257, 492. Lamarck, 58, 59. Lazzaro Moro, 4, 12. Lee, J. E., 353. Lehmann, 6, 7, 9. Liebig, 54, 217. Linnaeus, 6. Lister, 5, 11,27,51. Llyd, 11, 51. Logan, 217, 220. Lonsdale, 288, 293, 541. Lyell, 101, 105, 218, 220, 273, 381, 383, 429, 452, 454, 456, 457, 458, 459, 460, 466, 478,485, 487, 488, 489, 494, 555, 628. MacCulloch, 81, 86, 90, 92, 95, 509, 511, 516, 525, 526, 608. Majendie, 509. Mallet, 561, 62. Mantell, 313, 314, 315, 317, 318, 357. Meyer, 444. Miller, 138, 429, 462. Milne, 117. Mitchell, 9, 561. Moreton, 11. Morris, 57, 61, 122, 290, 297, 301, 383. Murchison, 6, 102, 104, 105, 117, 121, 160, 195, 198, 209, 251, 252, 258, 271, 290, 291, 292, 293, 298, 301, 303, 321, 357, 361, 362, 424, 429, 452, 454, 455, 456, 458, 459, 461, 507, 508, 513, 515, 528, 576. Necker, 515, 578. Nesti, 410. Newton, 4. Niebuhr, 2. Ormerod, 266. Otley, Jonathan, 101, 108. Overweg, 146. Owen, Dr. Dale, 105, 316, 383. Packe, 5. Palissy, 11. Phillips, 192, 288, 358 Playfair, 27, 466, 499. Plot, 11, 51, Pratt, 208. Preston, 175. Prestwich, 196, 383, 385, 386, 387. Pusch, 360. Pythagoras, 3. Ramazzini, 11, 12. Ramsay, 50, 102, 202, 508. Ray, 11, 51. Rogers, Prof. H. D., 210, 217,218, 429, 561. Saussure, 10. Scilla, 11. Sedgwick, 42, 71, 101, 102, 108, 117, 161, 249, 250, 251, 252, 255, 258, 307, 308, 361, 455, 507, 512, 522. Serres, M. de, 451, 460. Sharpe, 45, 208, 604, 608. Simms, 354. Smith, 13, 22, 69, 101, 180, 213, 292, 293, 306, 308, 314, 315, 351, 383, 403, 423, 470. Soreby, 45, 604. Steno, 4. 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