GEOLOGY 
 
 FOR 
 
 GENERAL EEADEES 
 
" The execution of such a project as this is greatly facilitated by the Lecturer's 
 happy prerogatives. The mere limits of time to which he is bound, preclude, iu 
 any case, his attempting the exhaustive treatment of his themes. At the lec- 
 ture-table he is only expected to display a few salient facts, in a striking and 
 attractive form, and to deduce therefrom a few guiding principles, so as to assist 
 his auditors in acquiring for themselves the details of the science. Any attempt 
 on the lecturer's part to make his brief discourses encyclopaedic, must, of neces- 
 sity, fail ; nay, lectures are probably by so much the better fitted for their pur- 
 pose, by how much they are freer from unnecessary detail, and more thoroughly 
 emancipated from the trammels of systematic routine." Hofmann's Introduction 
 to Modern Chemistry. 
 
 "Scientific method is no peculiar mystery, requiring a peculiar initiation. It 
 is simply common sense combined with uncommon courage, which- includes 
 common honesty and common patience ; and if you will be brave, honest, patient, 
 and rational, you will need no mystagogues to tell you what in science to believe 
 and what not to believe ; for you will be just as good judges of scientific facts 
 and theories as those who assume the right of guiding your convictions." Rev. 
 C. Kingsley in 'Fraser's Magazine' for July 1866. 
 
GEOLOGY 
 
 FOR 
 
 GENEKAL KEADEES 
 
 A SERIES OF POPULAR SKETCHES 
 
 GEOLOGY AND PALEONTOLOGY 
 
 BY 
 
 / 
 
 DAVID PAGE, F.E.S.E. F.G 
 
 or 'TZXT-BOOKS OF GEOLOGY AND PHYSICAL GKOGRAPHV," 'HANDBOOK cp 
 
 (iBOLOGICAJ. TERMS,' ' PAST AXD PRESENT I-IFB OF THB GLOBE/ 
 ' PH1LOSOFHV OF GBOLOOV,' BTC. 
 
 SECOND AXD ENLARGED EDITION 
 
 WILLIAM BLACKWOOD AND SONS 
 
 EDINBURGH AND LONDON 
 
 MDCCCLXVI 
 
 The Eight of Translation it reserved 
 
P B E F A C E. 
 
 DURIXG the last twenty years immense progress has 
 been made in the dissemination of Geological know- 
 ledge, yet still the old cry, " It is so difficult, so full of 
 technicalities, so hard to be understood." Now, with- 
 out admitting that Geology is fuller of technicalities, 
 or one whit more difficult to be understood, than other 
 sciences, I have thought it worth while, in the present 
 volume, to attempt a simple and familiar exposition of 
 its leading truths and principles. Because some have 
 made the same attempt and failed is no reason why 
 I should not try; because it is fashionable in some 
 quarters to sneer at popular sketches is no reason why 
 I should be deterred from expressing my conviction 
 that sketches of this kind are the only means by 
 which the majority of people can acquire any know- 
 ledge of science, while in many instances they form 
 the first steps even to those who subsequently profess 
 to despise them. Because information is given in a 
 popular way, it need not be inaccurate and flimsy ; 
 
VI PREFACE. 
 
 because it is told in a familiar manner, it need not be 
 either undignified or unattractive. 
 
 Discarding technicalities as much as possible, and 
 avoiding the formality of a text-book, I have still 
 arranged the subjects so as to present a connected 
 view of the science ; and he who reads them in order, 
 and understands as he reads, will have a fair concep- 
 tion of the scope and bearings of Geology. At the 
 same time, each sketch is complete in itself, and con- 
 tains, as far as it goes, an outline of our present know- 
 ledge of the matter to which it refers. This mode of 
 treatment may lead to an occasional repetition, but a 
 repetition in such cases is rather an advantage, as tend- 
 ing to render the matter more intelligible, and fix it 
 more enduringly on the memory. I may also men- 
 tion that several of the topics have been repeatedly 
 brought before miscellaneous audiences in the form of 
 popular lectures, and naturally indulge the hope that 
 what was appreciated by them will prove equally in- 
 viting and instructive to the miscellaneous reader. 
 
 D.P. 
 
 GILMORE PI^CE, EDINBURGH, 
 February 1866. 
 
SECOND EDITION. 
 
 THIS Edition, so speedily called for, contains few new 
 facts or discoveries, but it embodies three additional 
 chapters one 011 Metamorphism, or that internal 
 change which every rock in the earth's crust is in- 
 cessantly undergoing; another on Veins, their nature 
 and origin ; and a third on What we owe to our Coal- 
 fields. Besides these chapters, which seem necessary 
 in a compendium of General Geology, a number of 
 emendations have been made throughout the work 
 the author's desire being to render it still more ac- 
 ceptable to that extensive and ever-increasing section 
 of readers for whom it is specially intended. 
 
 October 1866. 
 
CONTENTS. 
 
 I. THE CRUST WE DWELL UPON. 
 
 PAGE 
 
 NATURE OF THE EARTH'S CRUST OR SOLID EXTERIOR DIFFERS 
 FROM THE INTERIOR COMPOSED OF ROCKS AND ROCK- 
 FORMATIONS THESE THE THEMES OF GEOLOGICAL INVES- 
 TIGATION TECHNICAL MEANING OF THE TERM "ROCK"- 
 STRATIFIED AND UNSTRATIFIED ROCKS HOW AND BY 
 WHAT PROCESSES FORMED OLDER AND YOUNGER ROCKS 
 EXAMPLES OF HOW DISTINGUISHED CHRONOLOGICAL AR- 
 RANGEMENT OF ROCK-FORMATIONSEACH A CHAPTER OF 
 WORLD -HISTORY ATTRACTIVE NATURE OF THIS HISTORY 
 FACTS ARRIVED AT BY A STUDY OF THE EARTH'S CRUST 
 THEIR THEORETICAL AND PRACTICAL IMPORTANCE, . 17 
 
 II. WASTE AND RECONSTRUCTION. 
 
 THE EARTH'S CRUST SUBJECT TO INCESSANT WASTE AND RE-^ 
 CONSTRUCTION SLOW AND GRADUAL NATURE OF THESE 
 CHANGES CAUSES OR AGENCIES PRODUCTIVE OF CHANGE : 
 1. METEORIC OR ATMOSPHERIC RAINS, FROSTS, AND WINDS 
 2. AQUEOUS RIVERS, WAVES, TIDES, AND OCEAN-CUR- 
 RENTS 3. CHEMICAL SOLUTION AND PRECIPITATION 
 4. ORGANIC PLANT AND ANIMAL GROWTHS 5. IGNEOUS 
 VOLCANOES, EARTHQUAKES, AND CRUST - MOTIONS THE 
 CRUST HELD IN EQUILIBRIUM BETWEEN WASTE AND RE- 
 CONSTRUCTION THESE ENDURING AS THE PLANETARY 
 
 SYSTEM, ....... 35 
 
CONTEXTS. IX 
 
 III. VULCANISM ITS NATURE AND FUNCTION. 
 
 DEFINITION OF THE TERM MODES OF MANIFESTATION VOL- 
 CANOES, THEIR VARIOUS ASPECTS, CHARACTERS, PRODUCTS, 
 AND FUNCTIONS EARTHQUAKES, THEIR MODES OF ACTION 
 AXD EFFECTS CONNECTION WITH VOLCANOES CRUST- 
 MOTIONS, THEIR CHARACTER AND RESULTS RECENT EX- 
 AMPLES THEORIES OF VULCANISM OR INTERNAL FIRE- 
 ACTION ITS SHIFTINGS FROM AREA TO AREA APPARENT 
 FUNCTIONS OF POWER AND PERMANENCE OF, AS A NAT- 
 URAL FORCE LAV BY WHICH REGULATED NECESSARY 
 PORTION OF WORLD-MECHANISM, . .51 
 
 IV. METAMORPHISM, OR THE TRANSFORMATIONS 
 OF ROCK-MATTER. 
 
 METAMORPHISM, DEFINITION OF THE TERM ALL ROCK-MAT- 
 TER INCESSANTLY UNDERGOING INTERNAL CHANGE THROUGH 
 PRESSURE, ATTRACTION OF COHESION, CHEMICAL ACTION, 
 HEAT, MAGNETISM, CRYSTALLISATION, AND OTHER SIMILAR 
 FORCES ILLUSTRATIONS OF THESE RESPECTIVE FORCES AND 
 THEIR MODES OF ACTION THEIR EFFECTS MOST PERCEPTIBLE 
 IN THE OLDER ROCKS THE SO-CALLED METAMORPHIC ROCK- 
 SYSTEMAPPARENT OBLITERATION OF ITS FOSSILS GRA- / 
 DUAL DETECTION OF THESE IN PECULIAR LOCALITIES RE- j 
 SOLUTION OF THE SYSTEM INTO MINOR SECTIONS AND CHRO- 
 NOLOGICAL ORDER INCONCEIVABLE AMOUNT OF TIME IM- 
 PLIED IN THE DEPOSITION AND SUBSEQUENT TRANSFOR- 
 MATIONS OF THE METAMORPHIC SYSTEM HOW TO DEAL 
 WITH IT AS A PART OF WORLD-HISTORY, . . 69 
 
 V. THE PRIMARY PERIODS. 
 
 OLDER AND YOUNGER PORTIONS OF THE EARTH'S CRUST 
 THESE REPRESENTED BY PERIODS OF TIME OR SYSTEMS 
 OF STRATA TECHNICAL ARRANGEMENT OF THESE PERIODS 
 AND SYSTEMS THE PRIMARY OR EARLIEST YET KNOWN, 
 EMBRACING THE LAURENTIAN, CAMBUIAN, AND SILURIAN 
 COMPOSITION AND DISTRIBUTION OF THESE RESPECTIVE 
 SYSTEMS THEIR CHARACTERISTIC ROCKS AND FOSSILS 
 GENERAL PAUCITY OF LIFE ADVANCE DURING THE SILU- 
 RIAN CYCLE OF CRYPTOGAMIC PLANTS AND INVERTEBRATE 
 ANIMALS GEOGRAPHICAL ASPECTS OF THE PRIMARY PE- 
 RIODSINTEREST ATTACHED TO THEM AS THE DAWN OF 
 WORLD-HISTORY, . .... 83 
 
X CONTENTS. 
 
 VI. VEINS THEIR NATURE AND ORIGIN. 
 
 VEINS AND DYKES, HOW OCCASIONED METALLIFEROUS VEINS, 
 MOST ABUNDANT IN THE PRIMARY ROCKS REASON OF 
 THIS ABUNDANCE GENERAL CHARACTERISTICS OF VEINS 
 VARYING NATURE OF THE MINERAL SUBSTANCES BY 
 WHICH VEINS ARE MAINLY FILLED MODE IN WHICH THESE 
 VEIN-STGFFS ARE AGGREGATED RELATIONS OF THE ORES 
 TO THE VEIN-STUFFS DIRECTION OF VEINS IN CERTAIN 
 LOCALITIES RIGHT-RUNNING AND CROSS VEINS THEORIES 
 OF FORMATION AND FILLING INFILTRATION AND DEPO- 
 SITION OF CHEMICAL SOLUTIONS EFFECTS OF THERMAL 
 AGENCY ELECTRIC AND OTHER KINDRED CURRENTS RE- 
 LATIONS TO CENTRES OF IGNEOUS ACTION IMPORTANCE OF 
 METALLIFEROUS VEINS CONTRAST BETWEEN THE MINERAL 
 AND AGRICULTURAL VALUE OF PRIMARY DISTRICTS MINES 
 AND STREAM-WORKS, . . . . .101 
 
 VII. FOSSILS-THEIR NATURE AND ARRANGEMENT. 
 
 THE TERMS FOSSIL AND SUB-FOSSILSCIENCE OF PALEONTOLOGY 
 FOSSILS, HOW IMBEDDED AND PRESERVED THEIR IM- 
 PORTANCE IN GEOLOGY INDICATORS OF GEOGRAPHICAL 
 CONDITIONS IN THE PAST OF NATURE AND KIND OF LIFE 
 DURING SUCCESSIVE PERIODS OF WORLD-HISTORY DIFFI- 
 CULTIES ATTENDING PAL.EONTOLOGICAL RESEARCH ORGAN- 
 ISMS MOST PERFECTLY PRESERVED PROCESSES OF PETRI- 
 FACTION CONDITIONS IN WHICH FOSSILS USUALLY OCCUR 
 REQUISITE SKILL FOR THEIR INTERPRETATION BOTANI- 
 CAL AND ZOOLOGICAL ARRANGEMENT OF THIS PRELIMI- 
 NARY KNOWLEDGE NECESSARY TO THE STUDY OF GENERAL 
 GEOLOGY, ...... Ill 
 
 VIII. THE OLD RED SANDSTONE. 
 
 INTEREST ATTACHED TO THE SYSTEM FROM THE LABOURS OF AG- 
 ASSIZ, HUGH MILLER, AND OTHERS ITS POSITION IN WORLD- 
 HISTORY NATURE OF ITS STRATA HOW FORMED LOWER, 
 MIDDLE, AND UPPER FORMATIONS TERRAQUEOUS ASPECTS 
 OF THE PERIOD ITS FLORA AND FAUNA GIGANTIC CRUS- 
 TACEA VARIED AND ABUNDANT FISH-REMAINS GEOGRA- 
 PHICAL OR EXTERNAL CONDITIONS OF THE OLD RED ERA 
 ECONOMIC PRODUCTS DERIVED FROM THE SYSTEM GENERAL 
 REVIEW, ...... 129 
 
CONTENTS. XI 
 
 IX. COAL AND COAL-FORMATIONS. 
 
 COAL, ITS ORIGIN AND FORMATION MINERALISED VEGETATION 
 RECENT PEAT-GROWTHS TERTIARY LIGNITES SECOND- 
 ARY AND PALEOZOIC COALS PRIMARY ANTHRACITES AND 
 GRAPHITES THE COALS AS A MINERAL FAMILY CONVER- 
 SION OF VEGETABLE SUBSTANCES INTO COAL ITS VARIOUS 
 STAGES PEAT, LIGNITE, COAL, ANTHRACITE, AND GRAPHITE 
 CHARACTERISTICS OF THESE RESPECTIVE STAGES IMPOR- 
 TANCE OF COAL TO CIVILISED COUNTRIES SPECIAL VALUE 
 OF, TO GREAT BRITAIN, .... 143 
 
 X. THE OLD COAL-MEASURES. 
 
 THE CARBONIFEROUS OR COAL SYSTEM ITS PLACE IN GEO- 
 LOGY NATURE AND COMPOSITION OF ITS STRATA ITS 
 UPPER, MIDDLE, AND LOWER DIVISIONS VARIETIES OF 
 ITS COALS APPARENT CAUSES OF IGNEOUS ROCKS ASSO- 
 CIATED WITH ITS STRATA ITS FOSSIL FLORA AND FAUNA 
 EXUBERANCE OF ITS PLANT-LIFE GENERAL GEOGRAPHI- 
 CAL CONDITIONS OF THE PERIOD THE COAL-MEASURES AS 
 AN ECONOMIC REPOSITORY VARIETY AND VALUE OF ITS 
 PRODUCTS THEIR INFLUENCE ON HUMAN CIVILISATION 
 AND PROGRESS EXTENT AND DURATION OF PALEOZOIC 
 COAL-FIELDS, ...... 159 
 
 XL WHAT WE OWE TO OUR COAL-FIELDS. 
 
 BRITAIN'S SUPREMACY IN MECHANICAL AND MANUFACTURING 
 INDUSTRY DEPENDENT ON HER COAL-FIELDS PHASES OF 
 MODERN AS COMPARED WITH THOSE OF ANCIENT CIVILISA- 
 TIONSDIFFERENCES ARISING CHIEFLY FROM THE USE OF 
 COAL AND IRON SPECIAL PRODUCTS OP OUR COAL-FIELDS 
 COAL AND ITS VARIETIES IRON AND THE AGE OF IRON 
 LIMESTONES AND MARBLES SANDSTONES AND THEIR 
 RELATIONS TO ARCHITECTURE FIRE-CLAY AND FIRE-CLAY 
 FABRICS SHALES, AND THE EXTRACTION OF ALUM, COP- 
 PERAS, PARAFFIN, AND PARAFFIN OILS ORES OF LEAD, 
 ZINC, AND SILVER RELATIONS OF MECHANICAL AND 
 MANUFACTURING INDUSTRY TO COAL AND IRON RELATIONS 
 OF INDUSTRY AND COMMERCE TO CIVILISATION AND RE- 
 FINEMENT, 177 
 
CONTENTS. 
 
 XII. THE SECONDARY AGES. 
 
 THE SECONDARY AGES, EMBRACING THE NEW RED SANDSTONE, 
 OOLITE, AND CHALK SYSTEMS THEIR PLACE IN GEOLOGI- 
 CAL HISTORY COMPOSITION AND SUCCESSION OF THEIR 
 STRATA PHYSICAL CONDITIONS UNDER WHICH THEY WERE 
 FORMED THEIR FOSSIL FLORA AND FAUNA EXCESS OF 
 CHAMBERED SHELLS EXUBERANCE OF REPTILIAN LIFE 
 CURIOUS PHASE OF BIRD-LIFE THE ARCH^OPTERYX 
 LIFE-CONDITIONS OF THE SECONDARY PERIODS ECONOMIC 
 PRODUCTS OF THE SECONDARY SYSTEMS SECONDARY COAL- 
 FIELDS THEIR GROWING IMPORTANCE, . .187 
 
 XIII. TERTIARY TIMES. 
 
 ORIGIN OF THE TERM TERTIARY LOWER, MIDDLE, AND UPPER, 
 OR EOCENE, MIOCENE, AND PLIOCENE TERTIARIES THEIR 
 MINERAL COMPOSITION AND SUCCESSION DIFFERENT IN 
 DIFFERENT BASINS OR AREAS OF DEPOSIT FLORA AND 
 FAUNA OF THE RESPECTIVE SUBDIVISIONS PHYSICAL CON- 
 DITIONS UNDER WHICH THESE GREW AND WERE DEPOSITED 
 GIGANTIC AND INTERMEDIATE FORMS OF EOCENE MAM- 
 MALS APPROXIMATION TO EXISTING DISTRIBUTIONS IN 
 MIOCENE AND PLIOCENE TIMES ECONOMIC PRODUCTS OF 
 THE SYSTEM, ...... 201 
 
 XIY. ICE ITS FORMS AND FUNCTIONS. 
 
 ICE, DEFINITION OF GENERAL PHYSICAL PROPERTIES OF 
 WATER FORMATION OF ICE ITS OCCURRENCE IN THE AT- 
 MOSPHERE : HOAR-FROST, SNOW, AND HAIL ITS OCCUR- 
 RENCE ON FRESH WATER : RIVER, LAKE, AND GROUND 
 ICE ON SALT WATER : ICE-FIELDS, ICE-PACKS, ICE-FLOES, 
 ETC., IN POLAR SEAS ICE ON LAND : SNOW AND SNOW- 
 LINE, AVALANCHES, N^VJE, GLACIERS THEIR CHARACTER- 
 ISTICS ICEBERGS GENERAL RESULTS OF ICE- ACTION, . 213 
 
CONTENTS. 
 
 XV. THE GLACIAL OR ICE EPOCH. 
 
 THE GLACIAL EPOCH AS DISTINGUISHED FROM THE PRE - GLA- 
 CIAL OR LATER TERTIARY ITS BOULDER-CLAYS, GRAVEL- 
 DRIFTS, AND ERRATIC BLOCKS LIMIT OF THESE IN THE 
 NORTHERN HEMISPHERE CONDITIONS UNDER WHiqH THEY 
 APPEAR TO HAVE BEEN FORMED ICE-MANTLE, GLACIERS, 
 AND ICEBERGS DURATION OF THE PERIOD PAUCITY OF 
 LIFE DEPRESSION AND RE-ELEVATION OF LAND GRADUAL 
 RETURN OF MORE GENIAL CONDITIONS ESTABLISHMENT 
 OF EXISTING ARRANGEMENTS, PHYSICAL AND VITAL RE- 
 CURRENCE OF COLDER AND WARMER CYCLES IN TIME, 231 
 
 XVI. RECENT FORMATIONS. 
 
 RECENT OR POST-TERTIARY FORMATIONS LATEST CHAPTER IN 
 GEOLOGICAL HISTORY FLUVIATILE : DALES AND RIVER- 
 TERRACES LACUSTRINE : ALLUVIAL FLATS AND STRATHS 
 ESTUARINE : PLAINS AND DELTAS MARINE : SILTS, SAND- 
 DRIFTS, AND RAISED BEACHES CHEMICAL : MINERAL PRE- 
 CIPITATES AND EXUDATIONS ORGANIC : VEGETABLE AND 
 ANIMAL GROWTHS VOLCANIC : LAVAS, TUFAS, ETC. EX- 
 TENT AND VARIETY OF RECENT FORMATIONS THEIR STUDY 
 THE KEY TO THOSE OF EARLIER DATES CHRONOLOGICAL AR- 
 RANGEMENT OF HISTORIC AND PRE-HISTORIC HUMAN 
 AND PRE-HUMAN, . . . . . 249 
 
 XVII. MAN'S PLACE IN THE GEOLOGICAL RECORD. 
 
 THE GEOLOGICAL RECORD NATURE OF ITS CHRONOLOGICAL 
 STAGES DIFFICULTIES AND IMPERFECTIONS COMPARATIVE 
 RECENTNESS OF MAN'S PLACE NATURE OF THE EVIDENCE 
 PREJUDICES TO BE COMBATED MAN'S EARLIER LIFE-COM- 
 PANIONS IN SOUTHERN AND WESTERN EUROPE THEIR RE- 
 MOVALS AND EXTINCTIONS TRACES OF HIS OWN RACE 
 PRE-HISTORIC AND HISTORIC AGES OF STONE, BRONZE, AND 
 IRON SHELL-MOUNDS, CAVE-DWELLINGS, LAKE-DWELLINGS, 
 ETC. MAN IN OTHER REGIONS GENERAL QUESTION OF 
 MAN'S ANTIQUITY HOW TO BE SOLVED, . . 273 
 
CONTENTS. 
 
 . ORDER AND SUCCESSION OF LIFE. 
 
 LIFE, ITS NATURE AND FUNCTION INTERDEPENDENCE OF 
 PLANTS AND ANIMALS HARMONY OF THEIR RELATIONS 
 THEIR EXISTING ASPECTS AND DISTRIBUTIONS ASPECTS 
 AND DISTRIBUTIONS OF THE PAST ADVANCE IN TIME FROM 
 LOWER TO HIGHER FORMS ORDER OF THIS PROGRESSION- 
 THEORIES OF LIFE-DEVELOPMENT HOW FAR PROBABLE 
 LAW OF CREATIONAL PROGRESS PROOFS OF ITS EXISTENCE 
 UNIVERSALITY OF ITS OPERATIONS ALIKE IN THE PHYSI- 
 CAL, VITAL, AND INTELLECTUAL ITS ENDURANCE, . 293 
 
 XIX. WHAT OF THE FUTURE ? 
 
 POSSIBILITY OF INDICATING THE FUTURE OF OUR PLANET 
 OPINION OF DR BUTTON EVERYTHING IN NATURE, PHYSI- 
 CAL AND VITAL, PASSING ON TO NEWER FORMS AND CON- 
 DITIONSNEW DISTRIBUTIONS OF SEA AND LAND NEW 
 CLIMATES AND PHYSICAL SURROUNDINGS NEW ARRANGE- 
 MENTS OF PLANTS AND ANIMALS NEW DEVELOPMENTS, 
 OR HIGHER AND HIGHER LIFE- FORMS MAN SUBJECT TO 
 THE SAME LAW OF PROGRESSION INFLUENCE OF MAN ON 
 THE FUTURE SLOW AND GRADUAL RATE OF NATURE'S OPE- 
 RATIONS EXALTED CONCEPTIONS OF THE UNIVERSE IN- 
 SPIRED BY THE BELIEF IN A LAW OF INCESSANT DEVELOP- 
 MENT AND PROGRESS, ..... 309 
 
XV 
 
 BRITISH STRATIFIED SYSTEMS, 
 
 TO WHICH THE FOLLOWING SKETCHES MORE ESPECIALLY REFER. 
 
 The subjoined tabulation exhibits the arrangement of the British stratified 
 rocks, as accepted by our leading geologists minor and local deviations 
 of superposition being subordinated for the sake of distinct comprehension 
 and ready reference : 
 
 Systems. 
 
 Groups. 
 
 Periods. 
 
 QUATERNARY. 
 
 TERTIARY. 
 
 CRETACEOUS. J 
 
 
 OOLITIC. 
 
 
 TRIASSIC. 
 
 
 PERMIAN. 
 
 
 
 CARBONIFEROUS. 
 
 
 
 2 ;T 
 
 
 ? ! 
 
 
 c 7: 
 S ^ 
 
 OLD RED SAND- 
 STONE. 
 
 a 
 
 SILURIAN. < 
 CAMBRIAN. 
 
 
 LAURENTIAN. J 
 
 CALNOZOIC. 
 
 MESOZOIC. 
 
 In progress. 
 
 Recent. 
 
 Pleistocene. 
 
 Pliocene. 
 
 Miocene. 
 
 Eocene. 
 
 Chalk. 
 
 Greensand. 
 
 Wealden. 
 
 Oolite. 
 
 Lias. 
 
 Saliferous Marls. 
 
 Muschelkalk (1) 
 
 Upper New Red Sandstone. 
 
 Magnesian Limestone. 
 
 Lower New Red Sandstone. 
 
 Coal-Measures. 
 
 Millstone Grit. 
 
 Mountain Limestone. 
 
 Lower Coal-measures. 
 
 Yellow Sandstones. 
 
 Devonian Limestones and 
 Slates. 
 
 Red Sandstones, Conglom- 
 erates, and Cornstones. 
 
 Grey fissile Sandstones 
 ("flagstones ") and Con- 
 glomerates. 
 
 Upper Flags, Shales, and 
 Limestones. 
 
 Lower Grits and Slates. 
 
 Slates, Schists, and Grits. \ 
 
 Gneissic Schists, Quart- fEozoiC, 
 zites, and Serpentines. / 
 
 PALEOZOIC. 
 
XVI 
 
 OEDER AND SUCCESSION OF LIFE, 
 
 ESPECIALLY AS REFERRED TO IN THE FOLLOWING SKETCHES. 
 
 The subjoined tabulation exhibits proximately the stages at which the 
 great ascending sections of Plants and Animals make their first appear- 
 ance in the stratified systems : 
 
 QUATERNARY. 
 
 TERTIARY. 
 
 CRETACEOUS. 
 
 f Man. Plants and animals o 
 I existing species and distribu 
 I tion ; a few genera recently 
 (^ extinct. 
 
 j Placental mammals. Plants 
 I and animals of existing or 
 \ ders ; a large proportion, 
 however, of extinct genera 
 ^ and species. 
 
 (Marsupial mammals, birds, 
 reptiles, fishes, shell-fish, 
 Crustacea, zoophytes ; palms, 
 . coniferae, ferns, lycopods, 
 
 OOLITIC. 
 TRIASSIC. 
 
 f Marsupial mammals, birds, 
 reptiles, fishes, shell - fish, 
 ( Crustacea, zoophytes; palms, 
 j cycads, coniferac, ferns, ly- 
 ^ copods, sea-weeds. 
 
 PERMIAN. f Reptiles, fishes, shell-fish, crus- 
 
 < tacea, zoophytes; coniferse, 
 CARBONIFEROUS. ( f erns> lycopods, sea- weeds. 
 
 OLD RED SAND- 
 STONE. 
 
 SILURIAN. 
 j I CAMBRIAN. 
 
 w ( 
 
 LAURENTIAN. 
 
 Fishes, shell- fish, Crustacea, 
 zoophytes; ferns, lycopods, 
 sea-weeds. 
 
 ( Shell-fish, Crustacea, worm- 
 t tracks, zoophytes; sea- weeds. 
 
 ( Crustacea, worm-burrows, and 
 ( zoophytes. 
 
 ( Traces of lowly or foramini- 
 ( feral organisms. 
 
FOR 
 
 GENEEAL EEADEES, 
 
 THE CRUST WE DWELL UPOK 
 
 NATURE OF THE EARTH'S CRUST OR SOLID EXTERIOR DIFFERS FROM 
 THE INTERIOR COMPOSED OF ROCKS AND ROCK-FORMATIONS 
 THESE THE THEMES OF GEOLOGICAL INVESTIGATION TECHNICAL 
 MEANING OF THE TEJIM "ROCK" STRATIFIED AND UNSTRATIFIED 
 
 ROCKS HOW AND BY WHAT PROCESSES FORMED OLDER AND 
 
 YOUNGER ROCKS EXAMPLES OF HOW DISTINGUISHED CHRONO- 
 LOGICAL ARRANGEMENT OF ROCK-FORMATIONS EACH A CHAPTER 
 OF WORLD -HISTORY ATTRACTIVE NATURE OF THIS HISTORY 
 FACTS ARRIVED AT BY A STUDY OF THE EARTH'S CRUST THEIR 
 THEORETICAL AND PRACTICAL IMPORTANCE. 
 
 WHEREVER we travel we find the land made up of rocks 
 and rocky substances. If we go to the sea-shores, we find 
 similar substances stretching away beneath the waters, or 
 rising up in mid-ocean as reefs and islands. The fair in- 
 ference therefore is, that all the exterior of our planet is 
 composed of rocks and rock-formations, and that the ocean 
 merely occupies the great hollows or depressions in the 
 same way as the lesser lakes and tarns occupy the rock- 
 
 B 
 
18 THE CRUST WE DWELL UPON. 
 
 basins of the continents and islands. To this rocky ex- 
 terior geologists apply the term " crust," much in the same 
 way as the housewife speaks of the crust of her loaf, or the 
 schoolboy of the crust of ice that forms on the stagnant 
 pool during the frosts of winter. The crust is something 
 hard and consistent, and may differ both in nature and 
 consistency from the interior on which it rests, or over 
 which it may be formed; and this is precisely the idea 
 entertained by geologists when they speak of the outer 
 shell or " crust of the globe." 
 
 The rocky exterior over which we travel, and into which 
 we dig and mine and tunnel, is a thing we can see and in- 
 vestigate to a limited depth ; but the interior, sinking away 
 four thousand miles to the centre, is placed altogether 
 beyond our reach and observation. It may consist of rocky 
 substances, but if so, they must be in a condition as to 
 density altogether different from those we find at the sur- 
 face ; for as a planet the earth has a certain astronomically- 
 ascertained weight, and were the force of gravitation to 
 exert itself to the centre on such rocks as we know, their 
 compression would give to the earth's mass a weight far 
 exceeding that which its astronomical relations will allow.* 
 Again, as we descend into the earth by mines, shafts, and 
 Artesian wells, the temperature seems to increase at a given 
 ratio (about one degree Fahr. for every 60 feet of descent); 
 and at this rate a depth would soon be reached at which 
 every known substance would be held in a state of incan- 
 descent fusion, or even vaporiform dispersion. It is conve- 
 nient, therefore, to draw a distinction between the " crust" 
 we can examine, and the " interior," respecting which we 
 
 * The reader must guard against the idea that at extreme depths 
 all substances suffer alike from mutual mechanical pressure. Their 
 different compositions forbid this supposition ; and their densities must 
 continue to depend (no matter what the depth) more on their chemical 
 nature than on the amount of compression to which they are subjected. 
 
MEANING OF THE TERM "ROCK." 19 
 
 can only form hypotheses. And it is this crust which con- 
 stitutes the great theme of geological investigation. What 
 is the nature of the rocks of which it is composed 1 how are 
 they arranged 1 hy what agencies have they been formed 1 
 what changes are they now undergoing ? and, reasoning from 
 the known to the unknown, what changes do they seem to 
 have undergone in former periods ? If we can answer all 
 these questions, or approach to anything like a reasonable 
 answer, we then present something like a history of our 
 planet; and such a history is the aim and object of all 
 sound geology. 
 
 \Ve have said that this earth-crust consists of rocks and 
 rock-formations ; and here we must explain that the term 
 " rock" is applied by geologists to all the solid substances 
 that enter into its composition. And there is good reason 
 for this usage. The sand and gravel of the sea-shore are 
 but comminuted rock-matters derived from the cliffs above; 
 the sands and loams and clays of the valleys are merely 
 rock-debris, worn and washed in course of ages from the 
 hills and uplands. Be it gravel or sand, clay or mud, all 
 are alike known to the geologist as " rocks;" and there can 
 be no doubt that, were these loose and soft matters con- 
 solidated by pressure or other agency, they would become 
 again compact and hard, like the rock-masses from which 
 they were originally derived. It is necessary, then, to bear 
 in mind this technical use of the term " rock ; " and the 
 least reflection upon the changes (mechanical and chemical) 
 which all rock-matter is incessantly undergoing will show 
 the appropriateness of the application. 
 
 Understanding, then, what geologists mean by the term 
 "rock," and bearing in mind that their labours are re- 
 stricted to the accessible crust, let us inquire a little more 
 narrowly into the nature of the rocks of which this crust is 
 composed, and the modes of their arrangement. Wher- 
 
20 THE CRUST WE DWELL UPON. 
 
 ever the structure of the crust is revealed whether along 
 the cliffs of the sea- shore, in ravines worn out by rivers, in 
 shafts sunk for mining, or in railway- cuttings and tunnels 
 we see the rock-masses arranged in two great ways. A 
 large and extensive class like the sandstones and shales 
 and limestones lie in layers or beds one above another; and 
 a second class like the granites, greenstones, and basalts 
 exhibit no lines of bedding or layers, but occur in vast and 
 indeterminate masses. These two modes of arrangement 
 may be seen in almost every railway-cutting and sea-cliff, 
 and must obviously have arisen from different causes. Now 
 the great maxim in geology is to reason from the known to 
 the unknown, and to appeal from the existing operations of 
 nature to the operations of the past. For, as was long ago 
 well remarked by Hutton, " when from a thing which is 
 well known we explain another which is less so, we then 
 investigate nature ; but when we imagine things without a 
 pattern or example in nature, instead of Natural History, 
 we write merely fable." Abiding by this method, we find 
 nature at the present day laying down, in every lake and 
 estuary and sea, layers of mud and sand and gravel, vary- 
 ing in thickness and continuity, according to the extent 
 of the areas and the magnitude of the in-flowing rivers; 
 and were these layers consolidated, sand would form sand- 
 stone, gravel conglomerate, and mud shale. Here then, 
 as we cannot regard nature acting in tune past otherwise 
 than at present, we are entitled to infer that all rocks in 
 the earth's crust occurring in layers have been formed 
 through and by the agency of water that is, that they 
 are the sediments of former lakes and estuaries and seas, 
 the particles of which they are composed having been worn 
 down by water, transported by water, and deposited in 
 water. Hence all such rocks are regarded as aqueous, sedi- 
 mentary, or stratified, and indicate that the areas they now 
 
STRATIFIED AND UNSTRATIFIED ROCKS. 21 
 
 occupy were at some former period the sites of lakes, estua- 
 ries, and seas. 
 
 In a similar manner we seek to explain the origin and 
 nature of the basalts and greenstones that rise up in homo- 
 geneous masses, and not in layers or bed above bed. And 
 when we go to the volcano or burning-mountain, and ob- 
 serve the discharges of molten lava, which when cooled 
 assume a structure scarcely distinguishable from that of 
 the basalts and greenstones, we are equally entitled to 
 infer that these have originated like lava, and consequently 
 have been formed through and by the agency of fire ; hence 
 we regard them as igneous or volcanic if we refer to their 
 origin, and unstratified if to their mode of arrangement. 
 There are thus in the crust of the globe only two great 
 categories of rocks the aqueous or stratified, and the 
 igneous or unstratified ; the former produced through and 
 by the agency of water, the latter through and by the 
 agency of fire. The stratified, by the waterworn particles 
 of which they are composed, and their sedimentary arrange- 
 ment, layer above layer, give evidence of the forces that 
 operate from without ; the unstratified, by their crystalline 
 texture and the manner in which they break through and 
 derange the sedimentary strata, of the forces that exert 
 themselves from within. 
 
 These two sets of rocks are being formed at the present 
 day the stratified or sedimentary in every lake, estuary, 
 and sea, and the unstratified or eruptive around every 
 active volcano. And, as nature's operations are incessant, 
 such rocks must have been formed during all time from 
 the current hour back through untold ages. Did the 
 watery forces rains, rivers, waves, tides, and ocean- cur- 
 rents alone prevail, the dry land would in course of time 
 be worn and wasted down to one uniform level, over which 
 the ocean might roll in uninterrupted continuity. But just 
 
22 THE CRUST WE DWELL UPON. 
 
 as certainly as waste and degradation are going on from 
 without, so the fiery forces the volcano and earthquake 
 are as incessantly operating from within, upheaving new 
 lands and mountains, and conferring on the whole new irre- 
 gularity and diversity of surface. The earth's crust is thus 
 held in equilibrium between these two opposing forces, fire 
 and water between waste and degradation on the one 
 hand, and reconstruction and upheaval on the other. In 
 this way former lands have been wasted and worn down, 
 and former estuaries and seas filled with the sediments; 
 old continents and islands submerged beneath the waters, 
 and the sea-bed upheaved into newer lands. The rocks of 
 the earth's crust are the only memorials of these repeated 
 changes ; and if geology is earth-history, it must endeavour 
 not only to decipher the changes they record, but to arrange 
 them in chronological sequence and connection. 
 
 When we look, then, at the changes now taking place 
 on the earth's crust, and the new rocks that are in process 
 of formation, we behold in them the exact counterparts 
 of what must have taken place during all former periods. 
 Winds, frosts, rains springs, streams, rivers waves, tides, 
 and ocean -currents are ever weathering and wasting the 
 rock-matter of the globe; and the matter worn down is 
 borne by rivers to lakes and estuaries and seas, and there 
 deposited in layers of mud and clay and sand and "gravel, 
 or further reasserted by the tides and currents of the 
 ocean. Coral-reefs, shell-beds, and other masses of animal 
 origin, are also accumulating in various parts of the ocean ; 
 while peat -bogs, swamps, and forest -'growths are adding 
 analogous masses of vegetable origin to the land. Hot- 
 springs and mineral -springs are also carrying matters in 
 solution from the earth's interior, and depositing these along 
 their courses ; while volcanoes are ever throwing out froni 
 the same interior showers of dust and ashes, and masses of 
 
ROCK-FORMATIONS. 23 
 
 molten lava. The earthquake also, which is but another 
 manifestation of volcanic agency, is ever breaking up the 
 rocky crust here raising the sea-bed into dry land, and 
 there submerging the dry land beneath the ocean here 
 rending and fissuring, and there producing inequalities and 
 varieties of surface. Whatever is worn and wasted from 
 one portion of the crust is laid down in another ; there is 
 nothing lost ; but the interchanges and variations are inter- 
 minable. The crust we dwell upon stable and enduring 
 as we are accustomed to regard it is thus a thing of inces- 
 sant change, protean in its superficial aspects, and ever- 
 shifting in its terraqueous arrangements. 
 
 If the earth's crust be thus continually worn away in 
 one district and reconstructed in another, some portions 
 like the lavas of Etna and the delta of the Gauges must be 
 comparatively recent, and others like the Grampian Moun- 
 tains and the coal-fields of Britain of vast antiquity. In 
 the former instances, the lavas and mud-islands are forming 
 beneath our observation ; in the latter, the formative pro- 
 cesses have ceased, and no perceptible change has occurred 
 for ages. To arrange the rock-formations of the earth into 
 chronological order is one of the first duties of geology, for 
 without this sequence there could be no history, and a con- 
 nected history of the changes this crust has undergone is 
 the great object of all geological investigation. By a rock- 
 formation is meant the strata that have been deposited in 
 any lake, estuary, or sea-area. The layers of mud, clay, 
 marl, sand, and gravel which have filled up any ancient 
 lake constitute a lacustrine formation ; the sediments that 
 are similarly deposited in estuaries an estuarine formation ; 
 and those deposited in seas, and subsequently upraised into 
 dry land, a marine formation. In course of time, by pres- 
 sure, chemical and other means, sands become sandstones, 
 gravels conglomerates, clayey muds shales, calcareous muds 
 
24 THE CRUST WE DWELL UPON. 
 
 limestones, muds largely impregnated with iron ironstones, 
 and vegetable masses coals ; and it is in this way that the 
 sediments of former lakes and estuaries and seas have 
 become the rocky strata that now constitute the crust of 
 the globe. As might be expected, there will often be every 
 degree of admixture among these rocky strata, just as there 
 is every degree of admixture and impurity among the sedi- 
 ments of existing seas and estuaries. There will be sand- 
 stones argillaceous, and sandstones calcareous ; shales bitu- 
 minous, shales calcareous, and shales ferruginous; limestones 
 argillaceous, and limestones siliceous ; coals so pure as to 
 burn away without leaving scarcely a trace of ashes, and 
 others so stony as to be altogether unfit for fuel. The solid 
 crust is, indeed, mainly made up of mixed rocks that is, of 
 arenaceous (sandy), argillaceous (clayey), calcareous (limy), 
 siliceous (flinty), bituminous (coaly), ferruginous (iron- 
 impregnated), and other similar compounds ; but whether 
 these rocks be sedimentary sandstones, grits, conglomerates, 
 shales, limestones, and ironstones, or fire -formed lavas, 
 greenstones, basalts, and granites, the great object of 
 geology is to distinguish between the older and newer, 
 to arrange them in chronological order, and so arrive, if 
 possible, at a knowledge of the geographical conditions 
 which accompanied their formation. Nor is this endea- 
 vour in the least chimerical or uncertain ; for as was well 
 remarked by Humboldt, now nearly half a century ago 
 " The superposition and relative age of rocks are facts sus- 
 ceptible of being established immediately, like the structure 
 of the organs of a vegetable, like the proportions of ele- 
 ments in chemical analysis, or like the elevation of a moun- 
 tain above the level of the sea. True Geognosy makes 
 known the outer crust of the globe, such as it exists at the 
 present day. It is a science as capable of certainty as any 
 of the physical descriptive sciences can be." 
 
OLDER AND YOUNGER FORMATIONS. 25 
 
 As a general rule, the oldest formations will be the 
 deepest-seated, or, in other words, the strata that lie be- 
 neath must be older than those that lie above them. Gene- 
 rally speaking, too, the older rocks will be harder and more 
 crystalline in texture than the younger. There may be 
 isolated exceptions to this, but the great fact holds good, 
 that the older formations are really the more crystalline, 
 and that this characteristic becomes less and less marked 
 till we arrive at the recent and superficial layers of clay, 
 sand, and gravel. Again, all the stratified rocks are less 
 or more fossiliferous that is, contain the petrified remains 
 of plants and animals and these fossils, as they are called, 
 lead to pretty correct inferences not only as to the relative 
 ages of formations, but as to the conditions under which 
 they were deposited. And they do it in this way. Every 
 lake, or estuary, or sea, imbeds in its sediments the re- 
 mains of plants and animals that have either been drifted 
 from the land by rivers or have lived and grown in the 
 waters of deposit. As these remains get imbedded in the 
 sands, clays, and calcareous muds, and excluded from the 
 action of the air, they gradually undergo a change, become 
 impregnated with mineral solutions, and in course of time 
 are petrified, or converted into stony matter like the strata 
 that contain them. At the present day the plants and 
 animals entombed in the delta of the Mississippi differ 
 widely from those entombed in the delta of the Ganges j 
 and were these deltas subsequently converted into rock- 
 formations, those plants and animals would afford evidence 
 of the kind of life and climate that prevailed in their re- 
 spective areas. It is in this manner that the fossils found 
 in the earth's crust bespeak the conditions under which 
 they lived aquatic or terrestrial, fresh- water or marine, 
 inhabitants of a cold climate or inhabitants of a genial one. 
 They further afford the best of all evidence as to the rela- 
 
26 THE CRUST WE DWELL UPON. 
 
 tive ages of formations the more recent containing the 
 remains of plants and animals nearly akin to those still 
 peopling the earth, while the more ancient contain plants 
 and animals that differ widely from the existing and this 
 difference increasing with the age of the formation. 
 
 Here, then, by means, first, of superposition, second, by 
 mineral composition, and, thirdly, by fossil remains, the 
 geologist can arrive at the relative ages of the rock-for- 
 mations that constitute the earth's crust, and can arrange 
 them into sections and systems and periods, just as the 
 historian arranges the reigns and dynasties and periods of 
 human history. As the one speaks of ancient, medieval, 
 and modern times, so the other speaks of primary, second- 
 ary, and tertiary systems. As the one groups the popula- 
 tions of the world into ancient, medieval, and modern, so 
 the other groups its life into eozoic, palaeozoic, mesozoic, and 
 cainozoic that is, dawn-life, ancient-life, middle-life, .and 
 recent-life. But while the geologist thus reads the history 
 of the earth mainly through its stratified rocks, he at the same 
 time receives important aid from its igneous or unstratified 
 masses. These, as volcanic products, break through the 
 stratified formations, throw them out of their horizontal 
 position, overflow them in part, insert themselves among 
 them as intrusive masses, and fill up rents and fissures in 
 the form of dykes and veins. All this gives ample evidence 
 of former change, and presents a lively picture of the opera- 
 tion of these gigantic forces which are still so instrumental 
 in modifying the existing aspects of our planet. In fine, 
 the whole crust is replete with evidence, physical and vital, 
 of the earth's former conditions. Our globe writes, as it 
 were, her own history every layer of mud and sand laid 
 down in water, every shower of ashes or sheet of lava 
 ejected from a volcano, every stem and twig, every shell 
 and tooth and scale preserved in sediment, forming an 
 
INTEREST OF ITS HISTORY. 27 
 
 incident in that progress which it is the great object of 
 geology to unfold. Geology is in fact the Physical Geo- 
 graphy of former ages. For just as the geographer endea- 
 vours to depict the existing aspects of sea and land, the 
 climates they enjoy, and the plants and animals by which 
 they are peopled, so the geologist labours to recall the 
 aspects of the past the distributions of sea and land at 
 each successive stage, the plants and animals by which they 
 were characterised, and by inference the nature of the phy- 
 sical conditions, genial or ungenial, by which they were sur- 
 rounded. The methods of the one are but the methods of 
 the other ; and the more the geologist knows of the exist- 
 ing operations of nature, the better will he be able to inter- 
 pret the operations of the past. The phenomena of the 
 present are patent, and for the most part explicable ; those 
 of the past are obscure, and, in proportion to their distance 
 and obscurity, the greater the interest excited and the in- 
 genuity required for their interpretation. 
 
 And surely if men take an interest in the history of their 
 own race in the mounds and barrows, the tombs and 
 pyramids, the towers and temples of bygone populations, 
 whose dates extend at most to a few thousand years much 
 more ought to be their enthusiasm in that higher history 
 which carries the inquirer from the historic to the prehis- 
 toric, and beyond the prehistoric into events and aspects 
 whose distance can only be indefinitely indicated by eras 
 and cycles. The events of the one history are scattered 
 over a small portion of the earth's surface, and for the most 
 part only under a few feet of rubbish ; the events of the 
 other are universal, and found in every stratum that enters 
 into the composition of the rocky crust. The events of the 
 one history are no doubt more direct and immediate ; but the 
 remoteness of the other, their strangeness and their variety, 
 should only excite our interest the more, and exalt our con- 
 
28 THE CBUST WE DWELL UPON. 
 
 ceptions of that Creative Wisdom which has exerted itself 
 in this world of ours ages before the human race became 
 witnesses of its beauties or participators in its bounties. 
 And the clearer we can render this history, the more 
 minute our analysis of the earth's crust ; and the closer the 
 connection we can establish between the successive stages 
 of its formation, the more attractive and instructive will the 
 geological record become. * 
 
 In arranging the rock-formations of the earth, we may 
 either divide them, as the older geologists did, into Pri- 
 mary, Secondary, and Tertiary ; or looking, as modern 
 geologists do, more especially at their fossils, we may adopt 
 the subdivisions, Eozoic, Palceozic, Mesozoic, and Caino- 
 zoic. In either case these main divisions contain several 
 formations of marine, estuary, or lacustral origin, and these 
 it is customary to name either after their prevalent rocks, 
 their most characteristic fossils, or some geographical area 
 in which they are typically displayed. Thus the Cretaceous 
 or Chalk system is so named from chalk -rock forming 
 its most distinctive feature in the south of England, and 
 the Old Red Sandstone from its consisting largely of red- 
 dish-coloured, sandstones; while the Silurian is named after 
 the district between England and Wales, where it is typi- 
 cally developed, and which was anciently inhabited by the 
 Silures, and the Laurentian because typically displayed in 
 the region of the St Lawrence. Adopting this plan (and 
 it matters little what the nomenclature, provided we be 
 certain of the chronological order), the stratified rocks of 
 the crust may be arranged in the following manner not 
 going into minutiae, but simply presenting such leading 
 features as may convey to the miscellaneous reader some idea 
 of the sequence that prevails among the stratified systems, 
 and the ascent of life, vegetable and animal, as it makes its 
 appearance from the lowest to the highest formations : 
 
* ** 
 -2 5 s 
 
 
 S | 
 
 
 
 
 oT to 
 
 I 2 
 
 
 C 
 
 ^ ^ 
 
 
 rt^ 
 
 42 o 
 
 
 00 B 
 
 r 
 
 
 a 
 
 ^3 
 
 <D ^ 
 
 | 
 
 ^0 
 
 ! J ~ 
 
 r* V^ 
 
 ^^ 
 
 "^ 
 
 'o 
 
 ag 
 
 
 
 -si 
 
 |1 
 
 = 
 
 CC q5 
 11 
 
 1 
 
 * 
 
 M 
 
 DIOZOXIVO -oiozosait 
 
 oiozoa 
 
30 THE CEUST WE DWELL UPON. 
 
 Studying the preceding scheme, it will "be seen how 
 numerous are the formations that compose the earth's crust, 
 each formation representing the sediments of former lakes 
 and seas, and each varying in composition according to the 
 conditions under which it was deposited. It will further 
 be seen that from the oldest to the most recent there has 
 been an ascent, in general terms, from the lower to the 
 higher forms of life the sea-weed preceding the fern, the 
 fern the conifer, the conifer the palm, and the palm the 
 true exogenous timber-tree ; and so in like manner the 
 zoophyte preceding the shell-fish, the shell-fish the fish, 
 the fish the reptile, the reptile the bird, and the bird the 
 mammal. We have thus revealed by a study of the earth's 
 crust, what our forefathers never dreamt of namely, that 
 this crust is in a state of incessant change, what was for- 
 merly dry land becoming the sea-bed, and what was once 
 the sea-bottom being upraised into dry land ; that these 
 old sea-sediments constitute the formations which com- 
 pose the earth's crust ; that these formations are replete 
 with the evidences of former life ; that this life evinces a 
 progress from lower to higher forms ; and that all the in- 
 terchanges of sea and land, all the waste and reconstruc- 
 tion, all the growth and decay of bygone life, establish an 
 antiquity for this world of ours vast beyond all human 
 conception. 
 
 Summing up, then, our knowledge of the rocky crust 
 and this without any conjecture as to the nature of the 
 earth's interior it may be stated in general terms, first, 
 That this rocky crust is in a state of slow but ceaseless 
 change, and that the causes meteoric, aqueous, igneous, 
 chemical, and organic that now waste and reconstruct 
 have been productive of similar changes in all time 
 past. Second, That these changes, like all other natural 
 operations, must be governed by imperative laws, and that 
 
DEDUCTIONS FROM ITS STUDY. 31 
 
 the mineral structure of the globe arising therefrom has 
 consequently a definite and determinable arrangement. 
 Tliird, That this arrangement, as displayed in the numerous 
 rock-formations, implies an enormous lapse of time time 
 to waste and wear, time to transport, and time to deposit 
 and reconstruct and therefore establishes an antiquity for 
 our globe vast beyond all previous conception. Fourth, 
 That during the long periods which these successive forma- 
 tions that is, successive distributions of sea and land 
 imply, the earth has been peopled by different races of 
 plants and animals all evidently belonging to the same 
 great scheme of life, but varying widely in their character- 
 istics during each succeeding epoch. Fifth, That during 
 these periods there has been an ascent, in the main, from 
 lower to higher forms ; and that the plants and animals 
 now inhabiting the globe are, on the whole, higher and 
 more specially organised than the plants and animals of 
 any former period. Sixth, That these successive appear- 
 ances and distributions of plants and animals are connected 
 together in one great scheme of life by some pervading law 
 of development which, though not yet satisfactorily dis- 
 covered, is evidently bound up with the operating forces of 
 the universe. And, lastly, The earth being still subjected 
 to the same causes of change and, from all we can see, to 
 the same law of development that operated in time past, 
 the future aspects of our planet must differ from the pre- 
 sent physically and vitally its present distribution of sea 
 and land giving place to other arrangements of sea and 
 land, and its present living races to others of a still higher 
 and more specialised organisation. 
 
 Such is the crust we dwell upon, and the teachings 
 which a study of its structure can convey. This rocky 
 exterior is all we know with certainty of the composition 
 
32 THE CRUST WE DWELL UPON. 
 
 of our planet the foundation of all geographical diversity, 
 the diversified habitat of plants and animals, the scene of 
 man's own life-labours, and the storehouse of those mine- 
 rals and metals upon which his civilisation and progress are 
 so intimately dependent. The study of its structure is 
 replete with intellectual interest of the most exalted de- 
 scription. The variety of its rock-formations, the minerals 
 and metals they contain, their modes of aggregation, and 
 the curious changes to which they have been subjected in 
 their repeated alternations from sea to land and from land 
 to sea, are all calculated to excite our interest and increase 
 our admiration of the means employed by the Creator to 
 alter, to diversify, and to sustain. And that interest and 
 admiration are increased a hundredfold when we perceive 
 in these formations the nature of the life that has preceded 
 us rising through long ages from the simple to the more 
 complex, from the simply sentient to the intellectual and 
 reflective, and this through forms so countless and varied, 
 and yet all belonging to the same great plan, that nume- 
 rous as are the existing forms of plants and animals, they 
 form but a tithe of those that have necessarily existed be- 
 fore them. No one, then, can look into the structure of 
 this crust without receiving newer and deeper insight into 
 the laws and ordainings of nature, and from all deeper in- 
 sight of nature the human intellect arises wiser, happier, 
 and more exalted. 
 
 But the study of the earth's crust is not less desirable 
 from its economic advantages than from its intellectual in- 
 terest. Man's civilisation and progress, and his mastery 
 over the powers of nature, are intimately dependent upon his 
 knowledge and application of the minerals and metals. In- 
 deed, modem civilisation and progress have largely arisen 
 from this knowledge of the minerals and metals; and as 
 these hold determinate positions in the various formations 
 
ADVANTAGES ARISING FROM ITS STUDY. 33 
 
 of the crust, an acquaintance with that crust is indispen- 
 sable to their acquisition. Gold and silver, coal and iron, 
 genis and precious stones, are not scattered indiscriminate- 
 ly through the earth. Some occur more abundantly in one 
 formation than in another ; some in beds, others in veins ; 
 some exclusively in one kind of matrix, others in another ; 
 and all this knowledge as to abundance, depth of strata, 
 direction of veins, and the like, can only be acquired by a 
 study of the structure and arrangement of the rocky crust. 
 Geology has thus all the interest of a wondrous Past to 
 attract ; it possesses all the value of a sterling Present to 
 incite to its study and acquirement. To the general reader its 
 revelations of world-history will ever form themes of intel- 
 ligent attraction ; to the miner, the engineer, the architect, 
 and others whose business is to deal with the structure and 
 products of the rocky exterior, its deductions are of direct 
 and special importance. 
 
 Such, once more, are the economic and intellectual ad- 
 vantages arising from a study of the structure of the crust 
 we dwell upon economic advantages of which our country, 
 in every department of its industry, is every day reaping 
 the benefit, and intellectual promptings which have led to 
 a newer and deeper insight into the laws and ordainings of 
 nature. We say newer and deeper insight, for with in- 
 creased knowledge of the past must extend our knowledge 
 of the present ; and the tendency of all true knowledge of 
 God's workings in nature must ever be to make men better, 
 wiser, and happier in all their relations to that nature of 
 which they form so prominent a part. Everything is 
 bound up one with another in the Divine scheme of the 
 universe ; and he who perceives this truth most fully in 
 the physical world is surely the most likely to regard it 
 in the intellectual and moral. On this ground alone, and 
 c 
 
34 THE CRUST WE DWELL UPON. 
 
 altogether independent of its intellectual pleasures and 
 economic advantages, the science of this earth -crust is 
 worthy of our closest cultivation leading the mind from 
 the harmonies that prevail in the natural world up to the 
 higher harmonies that ought to pervade the human and 
 social. 
 
WASTE AND RECONSTRUCTION. 
 
 THE EARTH'S CRUST SUBJECT TO INCESSANT WASTE AND RECON- 
 STRUCTIONSLOW AND GRADUAL NATURE OF THESE CHANGES 
 CAUSES OR AGENCIES PRODUCTIVE OF CHANGE : 1. METEORIC OR 
 ATMOSPHERIC RAINS, FROSTS, AND WINDS 2. AQUEOUS RIVERS, 
 WAVES, TIDES, AND OCEAN-CURRENTS 3. CHEMICAL SOLUTION 
 AND PRECIPITATION 4. ORGANIC PLANT AND ANIMAL GROWTHS 
 5. IGNEOUS VOLCANOES, EARTHQUAKES, AND CRUST-MOTIONS 
 THE CRUST HELD IN EQUILIBRIUM BETWEEN WASTE AND RECON- 
 STRUCTION THESE ENDURING AS THE PLANETARY SYSTEM. 
 
 " OUR solid earth is everywhere wasted, where exposed to 
 the day. The summits of the mountains are necessarily 
 degraded. The solid and weighty materials of those moun- 
 tains are everywhere urged through the valleys by the force 
 of running water. The soil, which is produced in the de- 
 struction of the solid earth, is gradually travelled by the 
 moving water, but is constantly supplying vegetation with 
 its necessary aid. This travelled soil is at last deposited 
 upon the coast, where it forms most fertile countries. But 
 the billows of the ocean agitate the loose materials upon the 
 shore, and wear away the coast, with the endless repetitions 
 of this act of power, or this imparted force. Thus the con- 
 tinent of our earth, sapped to its foundation, is carried 
 away into the deep and sunk again at the bottom of the 
 sea, whence it had originated, and from which, sooner or 
 later, it will again make its appearance. We are thus led 
 to see a circulation in the matter of this globe, and a system 
 
36 WASTE AND RECONSTRUCTION. 
 
 of beautiful economy in the works of nature." Such are 
 the words of Dr Hutton in his celebrated ' Theory of the 
 Earth/ towards the end of last century; and such the 
 conclusion at which every one must arrive who gives the 
 matter sufficient and enlightened consideration. But this 
 incessant transmutation of the solid framework of the globe 
 is a conception not readily realised by ordinary minds, partly 
 from the restricted range of observation during a single life- 
 time, and partly from our limited notions of time, which is 
 in itself illimitable and altogether independent of the events 
 that mark the course of its continuity. This difficulty was 
 not unforeseen by the Scotch philosopher, and so he goes 
 on to remark : " It is not to common observation that it 
 belongs to see the effects of time, and the operation of 
 physical causes, in what is to be perceived upon the surface 
 of the earth. The shepherd thinks the mountain on which 
 he feeds his flock to have always been there, or since the 
 beginning of things ; the inhabitant of the valley cultivates 
 the soil as his father had done, and thinks that this soil is 
 coeval with the valley or the mountain. But the man of 
 scientific observation, who looks into the chain of physical 
 events connected with the present state of things, sees great 
 changes that have been made, and foresees a different state 
 that must follow in time, from the continued operation of 
 that which actually is in nature." It is the object of the 
 present Sketch to place this system of waste and reconstruc- 
 tion of destruction and renovation in a clear and obvious 
 light, that the " common" as well as " scientific" mind may 
 perceive the means employed by the Creator to keep this world 
 of ours ever young notwithstanding its vast antiquity, and 
 to maintain its stability in the midst of incessant vicissitude. 
 
 To the casual observer the hills and valleys that surround 
 him appear unchanged and unchangeable. The plains and 
 
THEIR INCESSANT OPERATIONS. 37 
 
 battle-fields mentioned in ancient history, the sites of cities 
 and harbours, the courses of rivers, and the contour of 
 mountains, are much the same as when described one thou- 
 sand, two thousand, or even four thousand years ago. But 
 to him who looks a little more narrowly the case is altogether 
 different. The stream in the valley has cut for itself a 
 deeper channel, and has repeatedly shifted its course eating 
 away the banks on one side, and laying down spits of new 
 ground on the other. The cliffs in the hills are more 
 weather-worn and rounded, and a larger mound of rock-debris 
 has accumulated at their bases. The lakes of the old his- 
 toric plain are partly converted into marshes, and the marshes 
 into meadow-land ; the site of the old city on the sea-cliff 
 has been partly wasted away by the encroaching waves ; 
 and the ancient harbour, once at the river-mouth, is now a 
 goodly mile inland, and separated from the sea by a flat 
 alluvial delta. The Nilotic plain is not precisely the same 
 as when described by Herodotus ; the sunderbunds or mud- 
 islands of the Ganges have been largely augmented during 
 the last two hundred years ; and many areas that were laid 
 down on the charts of our earlier traders as mud-flats, now 
 form fertile portions of the great Chinese plain. Vesuvius 
 has repeatedly changed its aspects since Herculaneum and 
 Pompeii were buried beneath its ejections; and there is 
 scarcely an active volcano that has not materially added to 
 its bulk since the commencement of the current century. 
 
 Such changes are incessant, and though individually they 
 may seem insignificant, yet when viewed in the aggregate, 
 and continued from century to century, they assume a mag- 
 nitude commensurate with the crust of the globe itself, 
 every portion of which has repeatedly suffered degradation 
 and renovation, been repeatedly spread beneath the waters as 
 sediment, and as repeatedly reconstructed into newer strata 
 and upheaved into dry land. Imperceptibly as the rains 
 
38 WASTE AND BECONSTEUCTION. 
 
 and frosts may wear away the mountain-cliff, slowly as the 
 river may deepen its channel, gradually as the delta may 
 advance upon the estuary, and little by little as the volcano 
 may pile up its scoriae and lava, yet after the lapse of ages 
 the mountain will be worn down, the river-channel will be 
 eroded into a valley, the estuary converted into an alluvial 
 plain, and the volcano rear its cold and silent dome into the 
 higher atmosphere. All that is necessary is time, and this 
 is an element to which we can see no limit in the future, any 
 more than we can discover a beginning to it in the past. To 
 render these incessant mutations thoroughly intelligible, how- 
 ever, to the ordinary observer, it will be necessary to describe 
 the agents by which they are effected, and at the same time the 
 varying power of these agents according to the latitudes and 
 altitudes within which they operate. These agencies may 
 be conveniently arranged under five great categories ; name- 
 ly, 1, The Meteoric, or those like winds, rains, and frosts 
 depending upon the atmosphere; 2, The Aqueous, or those 
 like rivers, waves, and tides arising from the action of water ; 
 3, The Chemical, or those resulting from chemical actions and 
 reactions ; 4, The Organic, or those like peat-mosses and 
 coral-reefs depending on the growth and decay of plants 
 and animals ; and 5, The Igneous, or those like the volcano 
 and earthquake connected with the manifestations of heat 
 within the interior of our planet. Each of these agencies 
 has its own mode of working some chiefly wearing and 
 degrading, some degrading and at the same time accumulat- 
 ing, and others solely reconstructing. Let us now glance 
 at them in detail : 
 
 The principal effect of the Meteoric or Atmospheric agen- 
 cies is to weather and wear away. Slowly but surely the 
 gases and moisture of the atmosphere eat into every ex- 
 posed rock-surface. The disintegrated matter is washed 
 down by the rains, taken up by the runnels and streams, 
 
ATMOSPHERIC AGENCIES. 39 
 
 and borne onward by the rivers to the ocean. We often 
 see the effect of heavy rainfalls on exposed soils and sur- 
 faces in our own islands how they batter, loosen, and 
 carry away ; but our rainfall, amounting annually to some 
 30 or 40 inches, is trifling compared with the rainfall of 
 tropical and sub-tropical countries, ranging from 200 to 400 
 inches, and this concentrated for the most part within one 
 period of the year. It is not uncommon to hear travellers 
 speak of the soils being converted into mud, and of the 
 rivers running mud rather than water, and this solely 
 through the battering and dissolving influence of the 
 periodical rains. Again, frost in all the higher latitudes 
 and altitudes is annually performing a similar function. 
 The moisture that inserts itself into the pores and inter- 
 stices of all rock-substances is converted into ice during 
 frost ; ice occupies more space than the water of which it 
 consists, or, in other words, water expands during freezing ; 
 the particles of rock-matter are distended or forced asunder; 
 and when thaw comes, their cohesion being loosened, they 
 are washed away by the rains and carried down by the 
 streams and rivers. Every winter we see the disintegrating 
 effects of frost on the ploughed soils, road-cuttings, and sea- 
 cliffs of our own islands ; and this effect is manifested a 
 hundredfold in all the colder latitudes and" in all the higher 
 mountains, whether within tropical, temperate, or arctic 
 regions. The destructive power of frost is stupendous, 
 whether silently crumbling away the cliffs and precipices ; 
 discharging the avalanche and landslip down the mountain- 
 slope ; slowly grinding its way as the glacier through the 
 Alpine glen ; or transporting and dropping, as the iceberg 
 does, its burden of rock-debris over the floor of the ocean. 
 As with the rains and frosts, so to a certain extent with 
 the winds or aerial currents of the atmosphere. Wherever 
 there is rock-matter sufficiently light and loose, thence the 
 
40 WASTE AND RECONSTRUCTION. 
 
 winds will remove it and carry it away to some more shel- 
 tered locality. And if the set of the wind be constant, or 
 chiefly from one direction, like the trades and sea-breezes, 
 the result in the long-run will be very marked and per- 
 ceptible. By this means the dry sand of the sea-shore is 
 blown inland and beyond the reach of the tide into mounds 
 and hillocks (sand-dunes, as they are termed), and along 
 every shore in the world there are recently-formed expanses 
 of this nature, often like the " Landes" of France of vast 
 extent, and still in the process of augmentation. As with 
 the sands of the sea-shore, so with the sands of the arid 
 deserts ; they are driven hither and thither into dunes and 
 ridges, but chiefly forward in one main direction according 
 to the prevailing winds, and this to the obliteration of 
 streams and oases, and to the destruction of fertile valleys 
 that lie in their way. Gentle as it may seem, the drifting 
 of sand over the surface of granite and basalt has been 
 known to wear and polish down their asperities, and even 
 to grind out grooves and furrows like those produced by 
 the long-continued motion of glacier-ice or the flow of run- 
 ning water.* 
 
 But perceptible as may be the effects of the meteoric 
 forces, they are far less obvious than those produced through 
 and by the agency of water. The Aqueous are generally on 
 a larger scale ; and wherever streams and rivers run, waves 
 break and tides ebb and flow, there they are to be witnessed, 
 partly as degrading, but partly also as accumulating and re- 
 constructing forces. The mere passage of water over rock- 
 surfaces would of itself have little effect ; but as it bears 
 
 * At the Pass of San Bernardino in California,, Mr W. P. Blake (as 
 quoted by Professor Dana) observed the granite rocks not only worn 
 smooth, but covered with scratches and furrows by the sands that were 
 drifted over them. Even quartz was polished, and garnets were left 
 projecting from pedicles of felspar. Limestone was so much worn as to 
 look as if the surface had been removed by solution. 
 
AQUEOUS AGENCIES. 41 
 
 along its burden of sand and gravel and shingle, every par- 
 ticle "becomes a tool which grinds, and is in turn ground 
 down in the double process of attrition and erosion. Every 
 runnel and rivulet wears for itself a channel, and bears the 
 eroded material down to the river ; the river performs the 
 same operation, but on a larger scale, and with marked in- 
 tensity during floods and freshets, cutting out ravines and 
 gorges, or scooping out broader valleys, and transporting the 
 debris to the lower levels of lakes, estuaries, and the ocean. 
 There the mud and sand and gravel borne from the higher 
 grounds come at last to rest, subside as sediments, and are 
 thus spread out as alternating strata, to be consolidated by 
 pressure, chemical agency, and other means, and ready, when 
 the event happens, to be upraised as the rock-formations of 
 newer lands. In like manner, also, with the waves and 
 tides and currents of the ocean. Restlessly and for ever 
 eating into and undermining the sea-cliff, the waves encroach 
 upon the land, pound down the hardest material to shingle 
 and gravel and sand, and this with rapidity according to 
 the nature of the opposing cliff, and the manner it is dis- 
 posed to the impact of the breakers. The effects of wave- 
 action are perceptible along every exposed shore ; here in 
 the undermined and falling cliffs, there in caverns and 
 gorges, and in another part in the "needles" and outstand- 
 ing rock-masses that have been severed from the land. 
 What the waves have worn down the tidal ebb and flow 
 disintegrate still more, and scour and carry away to the 
 stiller depths and more sheltered recesses. And the great 
 ocean-currents, too like the Arctic with its burden of ice- 
 bergs and rock- debris, or the Gulf Stream with its drifted 
 sea-weeds and animal exuviae are also incessantly trans- 
 porting and reasserting. Everything, however, comes at 
 last to rest in the waters, being either piled on shore as 
 sand, gravel, and shingle, deposited as silt in the deeper and 
 
42 WASTE AND RECONSTRUCTION. 
 
 stiller waters, or strewn along the courses of the ocean-cur- 
 rents in long reaches of miscellaneous debris, partly of ani- 
 mal, partly of vegetable, and partly of mineral origin. The 
 effect of aqueous agency is thus partly to wear and waste, 
 and partly to accumulate and reconstruct to wear down 
 the old continents and to accumulate the abraded materials 
 in the waters for the formation of newer lands. 
 
 The Chemical agencies, though less perceptible, are not 
 less general or less incessant in their action than the mete- 
 oric or aqueous. Indeed, in a certain sense the meteoric 
 and aqueous act chemically but we have hitherto alluded 
 chiefly to their mechanical effects, and now direct attention 
 more especially to their chemical. The carbonic acid of 
 the atmosphere eats into the most crystalline marble ; its 
 oxygen converts the hardest ironstone into a soft earthy 
 peroxide, ready to be washed away by the first shower that 
 falls. Every spring that issues from the interior of the 
 earth holds in solution, less or more, some mineral or 
 metallic matter, which it either deposits along its course or 
 carries forward through stream and river to the ocean. Be 
 it lime, or iron, or flint, or salt and such matters constitute 
 our petrifying, chalybeate, siliceous, and saline springs 
 these matters must have been dissolved or wasted from the 
 interior, as they are now brought to its surface to form new 
 rock-masses or to enter into newer combinations in the 
 waters of the ocean. And this chemical effect of springs is 
 vastly increased when the waters are hot, whether bursting 
 forth like the Geysers of Iceland, or simmering like the mud 
 and sulphur vents that appear in the neighbourhood * of 
 almost every active volcano. Heat, indeed, is the great 
 promoter of chemical change within the earth's crust ; and 
 from this cause arise, no doubt, those discharges of naphtha, 
 petroleum, and the like, that result from the slow decom- 
 position of lignites, coals, and other organic masses. It is 
 
ORGANIC AGENCIES. 43 
 
 not to pressure alone, nor to volcanic heat alone, that the 
 solid strata, originally of sand, gravel, mud, and organic 
 debris, owe their hardness and crystalline texture. Chemi- 
 cal infiltrations and combinations are everywhere as opera- 
 tive as these are, and, indeed, in most instances are the main 
 modifiers of mineral texture, colour, and consistency. And 
 the veins and veinstones the great repositories of the 
 metallic ores that traverse the older formations, they, too, 
 are the immediate products of chemical segregation, slowly, 
 and silently, but ever at work in these secret recesses. On 
 the whole, chemical actions and reactions within the rocky 
 crust of the earth are incessant, either dissolving and dis- 
 placing, reconstructing into other forms, or aggregating in 
 other and newer compounds. 
 
 The Organic agents fall next to be considered, and of these, 
 as of many other departments of nature, it may be remarked 
 that the minute and unobserved are the most active and 
 effective. It is true that the trees of the forest may be im- 
 bedded in peat-bogs or drifted into the mud of estuaries, 
 and that the bones of fishes, reptiles, birds, and mammals 
 may be entombed in the sediments of lakes and seas ; but, 
 on the whole, these constitute a small proportion of the con- 
 taining strata, and even where swept by currents into special 
 shoals and bone-beds, as we know they are in certain parts 
 of the ocean, they form but insignificant accumulations 
 compared with those resulting from the myriad-growths of 
 microscopic organisms. In the vegetable world the plants 
 of the peat-moss and swamp-growth claim our first attention, 
 as out of the constituents of the air and water they elaborate 
 their own substance, and year after year bequeath it to the 
 accumulating mass. How thin soever may be the film that 
 the growth and decay of a single year may add to the ac- 
 cumulation, yet in the course of centuries the peat-growth 
 and swamp-growth thicken, till now within all the colder 
 
44 WASTE AND RECONSTRUCTION. 
 
 latitudes there are expanses of vast area and many feet in 
 depth entirely composed of decayed vegetation, and ready 
 to he converted into coal, like the analogous accumulations 
 of former epochs. In the animal world, on the other hand, 
 the coral-reef is perhaps the most striking instance of aggre- 
 gation by the minutest of means. Barely perceptible to 
 the naked eye, the tiny zoophyte, in countless myriads, 
 secretes the lime held in solution by the waters of the ocean, 
 till year after year and century after century the conjoint 
 structure so increases that at last the " reef " stretches away 
 many leagues in length and many fathoms in thickness. 
 As with coral-reefs so with beds of gregarious and drifted 
 shells, and so also with the enveloping limy and flinty 
 shields of microscopic organisms like the foraniinifera and 
 diatoms ; the former mere specks of animal jelly, the latter 
 mere points of plant-life, yet so increased by the immensity 
 of their numbers and the rapidity of their growth, that large 
 areas of the sea-bed as well as lakes and estuaries are thickly 
 strewn with their calcareous and siliceous envelopes. These 
 envelopes, though mere microscopic specks, are yet aggregated 
 in such myriads that they are capable of forming extensive 
 beds of limestone on the one hand, and of flinty rock on 
 the other. And such limestones and flint-rocks we find in 
 the solid crust, exhibiting to the eye of the microscopist 
 the beautiful organisms of which they are composed, and 
 proving that in former ages the earth's crust was built up 
 by the same agencies that still continue to remodel and up- 
 hold it. A great proportion of the chalk-rocks of England, 
 the nummulitic limestone that stretches from the Alps east- 
 ward through Europe and Asia on to the Philippine Islands, 
 and the mineral known as tripoli or polishing-slate, are 
 ancient strata formed by analogous microscopic organisms ; 
 and the same work still goes forward in the calcareous ooze 
 that covers so large an area of the Atlantic sea-bed, and in 
 
IGNEOUS AGENCIES. 45 
 
 the siliceous mud of most of our existing estuaries.* The 
 lime and the flint dissolved by springs from the crust of the 
 earth, and borne down by streams and rivers to the ocean, is 
 thus secreted by vital agency and once more converted into 
 solid rock-matter. Nothing is lost; it may change its 
 shape and pass out of sight for a while, but in the long-run 
 it will reappear, altered it may be in form, but essentially 
 the same in substance. Every particle of matter obeys a 
 ceaseless round of change. Now in the crystalline and 
 independent gem, at another time as a constituent of the 
 solid rock ; now dissolved in the limpid waters, at another 
 time built up in the structures of plants and animals ; now 
 scattered abroad as the decaying exuviae of life, and once 
 more collected into compact and rocky strata. 
 
 The Igneous agents generally exert themselves with signal 
 force and marked effects, and yet in some instances their most 
 gigantic results are brought about by stages that are almost 
 imperceptible. The most notable instance of their opera- 
 tion is perhaps in the volcano, which in course of ages piles 
 up its alternate discharges of dust and ashes and lava till it 
 assumes the lofty proportions of an isolated mountain like 
 Etna, or stretches away in long ranges like the fiery cones 
 of the Andes. Whether exerting itself on land or rising 
 up from the depths of the ocean, the volcano is one of the 
 most important modifiers of the earth's crust ; and it acts 
 partly by upheaval, partly by accumulation, and partly by 
 fusing and reconstructing rock-matter in the interior, and 
 by bringing it once more to the surface. In this function it 
 
 * Of the microscopic organisms the foraminifers, polycystines, dia- 
 toms, and desmids that stand, as it were, on the confines of Life, the 
 two former belong to the animal kingdom and the two latter to the vege- 
 table. The foraminifera secrete calcareous matter, the polycystines and 
 diatoms siliceous, and the desmids no appreciable quantity of either. 
 The foraminifera and diatoms, along with the coral-polypes, may there- 
 fore be regarded as the main microscopic rock-builders. 
 
46 WASTE AND RECONSTRUCTION. 
 
 is usually accompanied by the earthquake, which fractures 
 and dislocates the solid crust, uplifting one portion and 
 depressing another, submerging one area beneath the waters 
 and elevating another into dry land. Unlike the volcano, 
 the earthquake produces no direct change on the character 
 of the rocks ; but it is the great diversifier of the earth's 
 surface, creating new irregularities, and as a consequence 
 interfering with the action of the atmospheric and aqueous 
 forces that operate on that surface, as well as with the dis- 
 tribution of the life by which it is peopled. But beyond 
 the earthquake and volcano, with all their minor accompani- 
 ments of hot-springs, mud-springs, and the like, there seems 
 to be another and still more gigantic, though silent, mani- 
 festation of vulcanic power. We allude to those gradual 
 uprises and depressions of portions of the earth's surface 
 those crust-motions, if we may so speak by which certain 
 regions, like the shores of Scandinavia, Spitzbergen, and 
 Siberia, are being slowly raised above the sea-level, and other 
 regions, like the western coast of Greenland and that of the 
 Southern States of America, as slowly depressed beneath it. 
 Many countries, and our own islands among the rest, are 
 marked by lines of ancient sea-beach, denoting uprise above 
 the waters ; and could we only see beneath the ocean, we 
 believe there are other regions equally marked by terraces 
 of depression. There is no other power save Yulcanism, or 
 internal heat-force, to which we can ascribe these upheavals 
 and depressions of the crust ; but be this as it may, there 
 can be no doubt of such oscillations, and that they form 
 one of the appointed means by which the waste and recon- 
 struction of our continents are held in equilibrium, and new 
 distributions of sea and land accomplished. 
 
 The effect of these various agencies the atmospheric, 
 aqueous, organic, chemical, and igneous is thus not only to 
 mould and modify the exterior, but at the same time to build 
 
EQUILIBRIUM MAINTAINED. 47 
 
 up the interior structure of our planet. Their function is at 
 once to wear down the old and to reconstruct the new ; to 
 scatter abroad in one region and to accumulate in another. 
 And the new rocks reconstructed must necessarily bear the 
 closest relationship to the old from which they were derived. 
 Their hardness and compactness and crystalline texture is 
 merely a matter of time. Given time and the fitting con- 
 ditions, and the loosest sand will be converted into the most 
 compact sandstone, the softest mud into the hardest slate, 
 and the earthiest chalk into the most crystalline marble. 
 Though here separated for the purposes of elucidation, these 
 agents are ever working hand in hand the atmospheric 
 with the aqueous, the aqueous with the chemical, and the 
 chemical with the organic and igneous. And it is this com- 
 plicated working that renders the composition of the solid 
 crust so varied, the aspect of its rocks so different, and the 
 task of unravelling their history at once the trial and the 
 triumph of geology. 
 
 Such is a brief sketch a mere indication as it were of 
 the great forces by which the earth's crust is incessantly 
 modified, its rock -matter wasted and reconstructed, and 
 the equilibrium of its terraqueous distribution sustained. 
 Sketchy as the outline has been, the careful reader will have 
 perceived not only the nature of the modifying agents, but 
 the manner in which they operate and must feel convinced 
 that, small as may be their results over a given area or 
 during a given time, yet comprising the whole globe and 
 allowing for ages, they are sufficient to accomplish any 
 amount of change to destroy, in fact, the whole of the 
 existing continents and to reconstruct new ones from the 
 bed of the ocean, and this by degrees, and over and over 
 again, according to the course of Time, which is illimitable 
 and beyond all computation. He will also have perceived 
 
48 WASTE AND RECONSTRUCTION. 
 
 that, many as are the agents at work and complicated as are 
 their modes of action, yet, on the whole, they may be con- 
 veniently arranged into two grand categories namely, the 
 powers of waste and degradation from without, and the 
 powers of reconstruction and upheaval from within. As 
 surely as the meteoric and aqueous disintegrate and level, 
 so surely does the igneous reconstruct and upheave ; as 
 the chemical and vital dissolve and destroy in one area, so 
 they recombine and build up in another. There is nothing 
 so harmonious as this incessant round of mutation, nothing 
 so marvellous as the variety it produces, and yet nothing 
 so certain as the unity of design by which the whole is 
 combined into one intelligible system. Strange as it may 
 seem, even the comfort and development^ of man is indis- 
 solubly bound up with this system of vicissitude. It is 
 not the rugged and flinty hill-side that yields him his sus- 
 tenance. He cannot build his cities on its peaks or plough 
 its precipices. And yet these hills are the great store- 
 houses of future fertility. The rains, the frosts, the streams, 
 and the rivers are perpetually carrying down from their 
 heights the materials to form the fertile valleys washing 
 out from the old crystalline rocks the inorganic elements 
 indispensable to vegetable luxuriance. And on these moun- 
 tain-derived plains man has hitherto settled in communi- 
 ties and built his cities. The plains of the Old World, 
 the historic fulfilments of the past China, Hindoostan, 
 Mesopotamia and Egypt were borne down from the 
 mountains of Asia and Africa ; just as the prairies, the 
 llanos, and pampas of the New World, the hopes of the 
 advancing future, are the gifts of the Andes and the Eocky 
 Cordilleras. How marvellous this system of interdepend- 
 ence between the organic and inorganic between the 
 mechanical processes of nature and the social development 
 of man ! How admirable this system of unceasing rejuven- 
 
THEIR HARMONY AND PERMANENCE. 49 
 
 escence ! the old Mils worn and wrinkled and furrowed 
 by decay, and the younger valleys spreading out in their 
 beauty and freshness and fertility ! 
 
 " This earth, like the body of an animal," said Hutton, 
 " is wasted at the same time that it is repaired. It has a 
 state of growth and augmentation; it has another state, 
 which is that of diminution and decay. This world is thus 
 destroyed in one part, but it is renewed in another ; and 
 the operations by which this world is thus constantly re- 
 newed are as evident to the scientific eye as are those in 
 which it is necessarily destroyed." And yet how few will 
 take the trouble to comprehend this system of incessant 
 change, contented to live in the belief that this earth has 
 always been as it is, has been so from the beginning, and 
 will continue to be so to the end ! Verily they deprive 
 themselves of much rational enjoyment, pay little regard 
 to the system of nature of which they form so prominent 
 a part, and show little reverence for Him who has given 
 them eyes to see, and understanding to understand, so be 
 it they will only learn to exert them. How admirable the 
 system of compensation by which decay in one part is bal- 
 anced by renovation in another ! The substances disinte- 
 grated by water are again reconstructed by fire ; the matter 
 dissolved by chemical action is collected anew by vital; 
 and what was appropriated for a while by the living organ- 
 isms is restored again to the mineral world when vitality 
 has ceased its requirements. Everything in this universe 
 is indissolubly woven into a network of interdependence, 
 and not a mesh could be taken away without destroying 
 the beauty and consistency of the whole. 
 
 " From nature's chain whatever link you strike, 
 Tenth, or ten-thousandth, breaks the chain alike ! " 
 
 And the reason is obvious ; for most of the operating forces 
 we have described arise directly from the earth's primal 
 
 D 
 
50 WASTE AND RECONSTRUCTION. 
 
 connections as a member of the solar system. Annual 
 revolution and daily rotation, daily and seasonal alternations 
 of heat and cold, currents and counter-currents of wind, 
 evaporation and rainfall, waves and tides, currents and 
 counter-currents of water, are all results of the earth's rela- 
 tion to the sun and her sister-planets. So in like manner 
 are the phenomena of vegetable and animal growth; so, 
 too, are many of those chemical and electro-magnetic activi- 
 ties with which science is but slenderly acquainted ; and so 
 also, perhaps, though in a remoter degree, that manifesta- 
 tion of internal vulcanism concerning which philosophy 
 can do little more than merely hazard conjectures. So 
 long, therefore, as the earth's primal relations endure, these 
 secondary forces must operate as a necessary consequence, 
 and thus the rocky crust must continue to undergo a round 
 of waste and reconstruction as ceaseless as the revolutions 
 of the planetary system, and as permanent in its power. 
 How harmonious the system by which this earth, in the 
 midst of all its mutations, is kept ever fresh and young ! 
 Day after day, and year after year, the aspects are cease- 
 lessly changing, but the vitality remains the same ; cycle 
 after cycle the forces may shift their direction, but their 
 power remains unimpaired. Everything around us being 
 seemingly stable, it may be difficult to realise this concep- 
 tion of incessant change, just as it is impossible to estimate 
 the lapse of time required for its fulfilment ; but an effort 
 must be made, and not till the mind has learned to form 
 some idea of the ceaseless mutations to which the earth's 
 crust is subjected, the causes by which these mutations are 
 effected, and the amount of time required for their produc- 
 tion, can it be said to comprehend the fundamental truths 
 upon which the science of geology is erected. 
 
VULGARISM ITS STATUKE AND FUNCTION. 
 
 DEFINITION OF THE TERM MODES OF MANIFESTATION VOLCANOES, 
 THEIR VARIOUS ASPECTS, CHARACTERS, PRODUCTS, AND FUNCTIONS 
 EARTHQUAKES, THEIR MODES OF ACTION AND EFFECTS CON- 
 NECTION WITH VOLCANOES CRUST-MOTIONS, THEIR CHARACTER 
 AND RESULTS RECENT EXAMPLES THEORIES OF VULCANISM OR 
 INTERNAL FIRE-ACTION ITS SHIFTINGS FROM AREA TO AREA 
 APPARENT FUNCTIONS OF POWER AND PERMANENCE OF, AS A 
 NATURAL FORCE LAW BY WHICH REGULATED NECESSARY POR- 
 TION OF WORLD-MECHANISM. 
 
 WHATEVER be the nature and origin of the thermal forces 
 that operate within the crust of our earth whether deep- 
 seated or near the surface whether arising from chemical 
 actions or dependent on some primordial condition it is 
 convenient to arrange them under one general term, and 
 that of Vulcanism or Vulcanicity, suggested by Humboldt 
 in his ' Cosmos,' seems by far the most comprehensive 
 and appropriate. In this way, not only the volcano pro- 
 per, but the earthquake, hot-springs, gas-springs, mud- 
 springs, and all kindred phenomena, are brought under one 
 category; and "it is really advantageous," as remarked by 
 the great German philosopher, "to avoid the separation of 
 that which is causally connected, and differs only in the 
 strength of the manifestation of force, and the complication 
 of physical processes." Here, then, we give to the con- 
 stantly active reaction of the interior of the earth upon its 
 external crust or surface the name of Vulcanism ; and the 
 
52 VULCANISM ITS NATURE AND FUNCTION. 
 
 object of the present Sketch is to describe the operations of 
 this internal heat, to explain what is known of its origin, 
 and to define its apparent function in the economy of na- 
 ture. To render a subject intelligible it is necessary to be 
 methodical ; and we shall therefore, without any assumption 
 of technical exactitude, arrange all the thermal phenomena 
 of our globe under the three great heads of Volcanoes, 
 Earthquakes, and Crust-Motions. 
 
 Every one is less or more acquainted with the aspect and 
 nature of a Volcano or burning-mountain. Whether he has 
 seen one or not, his readings and hearings lead him to asso- 
 ciate with his idea a mountain of a conical form, having a 
 crater or orifice of eruption at top, and from which at inter- 
 vals are emitted clouds of vapour and flame, showers of 
 dust and ashes, and streams of lava or molten rock-matter. 
 The outline may not be strictly conical, yet such is the 
 form which it usually assumes ; there may be more craters 
 or orifices than one, some being central or near the top, and 
 others lateral or placed along the sides ; and the sub- 
 stances discharged may be very heterogeneous now highly 
 heated steam and sulphurous vapours, now dust and cindery 
 matters called sconce, now fragments of rock (lapilli and 
 volcanic bombs), and anon wellings-out of lava, sometimes 
 extremely fluid and at others slaggy and cindery. Notwith- 
 standing such local and periodic differences, there is, on the 
 whole, a great similarity in aspect and operation between 
 all volcanoes, which leads to the belief that they belong to 
 one brotherhood, and to the same system of causation. It 
 is usual to speak of lava-cones, tufa-cones, cinder-cones, and 
 mixed cones, according as a mountain is chiefly composed of 
 one or other of these substances, or of a mixture of all of 
 them; but, as might be anticipated, the mixed cones are by 
 far the most prevalent,, and the distinction is mainly valu- 
 
VOLCANOES. 53 
 
 able in assisting the observer to determine the composition 
 of distant or inaccessible volcanoes. Thus the slope of a 
 lava-cone is very gentle from 3 to 10 degrees; that of a 
 tufa-cone from 15 to 30 degrees ; of a cinder-cone from 35 
 to 45 degrees ; and that of a mixed cone usually gentle 
 beneath, but topped with a steep peak of loose and scoriace- 
 ous materials. Again, some are strictly sub-aerial that is, 
 take place on the dry land and others sub-aqueous that is, 
 operate under the waters, or but rarely manifest themselves 
 at the surface ; yet both seem to act in a similar way, and 
 to discharge similar products. Further, some are cease- 
 lessly active; others become active only at long intervals, 
 and are said to be dormant ; while others have been so 
 long dormant and shown no symptoms of activity that they 
 are regarded as extinct. Between the existing and the ex- 
 tinct there is every grade of activity, just as among the 
 extinct there is every degree of antiquity. We are thus 
 led from the active craters of Etna and Vesuvius back to 
 the extinct cones of Central France and the Rhine, which, 
 in their crateriform domes and rugged .lava-streams, still 
 retain the aspect of volcanoes ; from these back through the 
 Apennines and Alps ; from the Alps to the Pyrenees ; and 
 from the Pyrenees to the Scandinavian and older mountain- 
 ranges, which have all had the same origin, though now 
 their craters and domes are obliterated, and their outlines 
 have undergone a thousand modifications from those denud- 
 ing agencies of air and water which have operated upon 
 them during untold ages. And here the reader cannot be 
 too strongly impressed with the fact that the profiles of all 
 our existing hill-ranges are more the results of waste and 
 denudation from without, than of upheaval and accumula- 
 tion from within. When a mountain is first presented to 
 us, the natural idea is, no doubt, that of upheaval and 
 accumulation, but a little reflection will soon correct the 
 
54 VULCANISM ITS NATURE AND FUNCTION. 
 
 misconception. All the older lands have been repeatedly 
 under the sea, and have suffered at each depression and re- 
 elevation the denuding effects of wave and tidal action. 
 Even since their latest re-elevation, the rains, frosts, and 
 rivers have been incessantly wearing, wasting, and eroding 
 so much so, that the older mountain-ranges are but the 
 merest skeletons of what they once were. Vulcanic agency 
 may block out, as it were, the contours and profiles of the 
 land ; but the meteoric and aqueous agents the frosts, 
 rains, rivers, and waves are the busy chisellers that are 
 for ever conferring upon it its latest features the latest, 
 but never the last. 
 
 In looking upon the more ancient hills, as well as upon 
 existing volcanoes, a question naturally arises Are these 
 elevations chiefly uplif tings of the earth's solid crust, or are 
 they accumulations of igneous matter that have been dis- 
 charged from its interior ? In other words, are mountains 
 and mountain-ranges mainly produced by upheavals or 
 swellings-up of the earth's rocky crust, or have they been 
 accumulated on the surface by repeated discharges of vol- 
 canic matter 1 Much controversy has existed on this point, 
 and many arguments adduced on both sides ; but the truth 
 seems to be, that the forces from within have acted in both 
 ways partly by elevation of the stratified crust, but chiefly 
 by the accumulation of erupted materials. In this view 
 every mountain and mountain-range becomes a matter of 
 slow and gradual growth, every shower of ashes and stream 
 of lava adding to the bulk of the isolated cone, and every 
 new cone adding another link to the mountain-chain. We 
 have no exact measure of this slow and gradual accumula- 
 tion, but judging from the small amount that has been 
 added to Etna and Vesuvius during the historical period, 
 many of the existing volcanoes must be of vast antiquity ; 
 and when we carry our retrospect back through the extinct 
 
EARTHQUAKES. 55 
 
 volcanic hills to the ancient mountain-ranges, the mind is 
 altogether unable to grasp the cycles that must have elapsed 
 since their formation. 
 
 Presuming, then, that volcanic hills are chiefly masses of 
 accumulation and not of upheaval, the repeated eruptions 
 that take place must necessarily fracture and derange the 
 continuity of the surrounding district, and thus every 
 igneous centre is marked by such accompaniments as hot- 
 springs, boiling mud -springs, discharges of sulphurous 
 gases, and the like, better known perhaps as the suffi- 
 oni and solfataras of Italy, and the salses, hornitos, and 
 hervideros of Mexico and South America. Such minor 
 discharges are the normal accompaniments of all active 
 volcanoes, and long after activity has ceased they form the 
 residual phenomena, and indicate by their declining force 
 and numbers the distance both in time and place of the 
 fiery forces that once operated below. No doubt springs of 
 considerable temperature may exist in districts long since 
 quiescent, and now far removed from volcanic activity 
 (those of Bath and the Pyrenees, for example); but the 
 monticules thrown up by mud -volcanoes and escapes of 
 heated and sulphurous vapours generally mark either the 
 proximity of igneous activity or the comparative recentness 
 of its manifestations in the area. The whole are merely 
 indications of the same thermal agency that internal fire- 
 force which Humboldt has so appropriately included under 
 the name of Yulcanism or Vulcanicity. 
 
 The next great manifestation of vulcanism is the Earth- 
 quake, a distinction made in scientific as well as in every- 
 day language ; for though the earthquake is generally the 
 close concomitant of the volcano, yet its throes may be felt 
 in districts where no volcano has existed for ages. This 
 motion, as the name implies, is a quaking or trembling of 
 
56 VULCANISM ITS NATURE AND FUNCTION. 
 
 the earth varying from the gentlest tremor to agitations 
 so violent that the solid crust is fractured, one portion 
 thrown up and another thrown down, the sea-bed uplifted 
 into dry land, and the dry land submerged beneath the 
 waters. The phenomena that accompany earthquake con- 
 vulsions are extremely varied. Occasionally they are preced- 
 ed by an unusual stillness and sultriness of the atmosphere ; 
 low hollow rumblings, more audible than felt ; and great 
 restlessness and terror among birds and mammals, as if the 
 instincts of these were keener than human perception. At 
 other times there is no premonition, but all at once a few 
 sma*t concussions, passing away in a certain direction, or 
 not unfrequently spreading from a central point in dimin- 
 ishing intensity. On other occasions, however, the mo- 
 mentary concussions return after a short pause with increased 
 vehemence, and then there is a perceptible undulation of 
 the earth's crust, as if it were passing away from beneath 
 the feet of the spectator an uplift, a shock, a series of 
 giddy shocks, and the work of destruction. Though con- 
 tinuing at most for a few seconds, these violent shocks 
 generally result in extensive fracturing of the rocky crust. 
 Yawning rents and fissures, gaseous discharges, bursting 
 forth of new springs, absorption of streams, changing the 
 course of rivers, elevation of the sea-bed, submerging of 
 the dry land, and the conversion of populous cities into 
 masses of ruin and rubbish, are the not unfrequent but 
 destructive effects of the earthquake. At times too, as the 
 water in a vessel that has been agitated and then brought 
 suddenly to rest strikes forcibly over its margin, so the sea, 
 its floor having been shaken, is frequently thrown into 
 violent waves (earthquake-waves), which rush forward 
 against the land to the height of 40, 50, or 60 feet, and 
 sweep everything into destruction before them. The wave 
 that rolled in upon the coasts of Portugal after the great 
 
CRUST-M 
 
 Lisbon earthquake in 1755 was 
 and the succession of such waves (three in number) that 
 desolated the town of Simoda (Japan) in 1854 were little 
 inferior in violence and dimensions. 
 
 On the whole the effects of the earthquake are much more 
 disastrous than those of the volcano. The discharges of 
 the one, being at considerable altitude, are chiefly felt for a 
 few miles round its crater or in long narrow streams down 
 its sides ; but the other convulses for leagues, and this at 
 all levels and alike over land and over sea. The two, how- 
 ever, are usually in close connection; and in centres of 
 igneous activity, when the volcano begins to discharge, the 
 convulsions of the earthquake cease, or at all events lose 
 much of their intensity. The one acts as a sort of safety- 
 valve to the other, and this necessarily so if we regard them 
 as both arising from the same deep-seated source of igneous 
 intensity. This connection was long ago noticed by Dr 
 Hutton, who quaintly but somewhat bitterly remarks " A 
 volcano is not made on purpose to frighten superstitious 
 people into fits of piety and devotion, nor to overwhelm 
 devoted cities with destruction. A volcano should be con- 
 sidered as a spiracle to the subterranean furnace, in order to 
 prevent the unnecessary elevation of land and fatal effects 
 of earthquakes. And we may rest assured that they, in 
 general, wisely answer the end of their intention, without 
 being in themselves an end, for which nature had exerted 
 such amazing power and excellent contrivance." 
 
 The third great manifestation of the reaction of the 
 earth's interior upon its external crust consists in those 
 slow movements by which certain portions of the land are 
 stage by stage elevated above the waters, and other por- 
 tions as gradually depressed beneath them. To this 
 manifestation we may apply the name of Crust-Motion, as 
 
58 VULCANISM ITS NATUEE AND FUNCTION. 
 
 indicating a slow and long -continued movement of the 
 solid crust in the region where it occurs, in contradis- 
 tinction to the volcano and earthquake, whose operations 
 are sudden and convulsive. "Whether these gradual crust- 
 movements result from the same igneous forces that give 
 rise to the earthquake and volcano is a matter open to 
 question, but in the present state of our knowledge we can 
 perceive no other adequate cause, and are therefore com- 
 pelled to associate them with the same pervading vulcan- 
 icity. Along the coasts of our own islands, and indeed 
 along the coasts of every other country, the attentive ob- 
 server will perceive at various levels above the present 
 sea-beach several shelves or terraces, which meet the eye 
 like reaches of former shore-line. On closer inspection, 
 their parallelism, the sand and gravel of which they are 
 composed, the shells, bones, and other marine exuviae which 
 they contain, prove incontestably that the sea formerly 
 stood at these levels, and that the land to this extent has 
 been successively elevated above the waters. Whether 
 such elevations took place suddenly or by slow degrees it 
 is often impossible to tell, but it is readily seen from the 
 old beaches and the cliffs that guard them that the sea 
 must have long stood at their successive levels. If the 
 movement takes place suddenly like that which during 
 the present century elevated the coast of Chile to the 
 height of eight or ten feet, or that which depressed the 
 Eun of Cutch, or that which more recently uplifted part of 
 the north island of New Zealand to the height of six feet or 
 thereby it is generally ascribed to earthquake convulsion ; 
 but if it occurs by slow stages it is regarded as crust-motion, 
 the proximate cause of which is at present unknown. 
 
 As notable instances of this crust-motion we may point 
 to the shores of Scandinavia, which have been long known 
 to be rising at a slow and equable rate ; to the raised beaches 
 
CRUST-MOTIONS. 59 
 
 of Spitzbergen, as described by Mr Lament and other recent 
 visitors; to the ancient shore-lines of Siberia, as amply illus- 
 trated by Von Wrangell ; the numerous terraces of uprise 
 noticed by Dr Kane and other Arctic voyagers on the coasts 
 of Greenland and the Arctic islands; the terraced shores of 
 Patagonia, long since observed by Mr Darwin ; as well as 
 to the less distinct, because more ancient, shore-lines that 
 encircle our own islands and the opposite coasts of France 
 and the Spanish Peninsula. As with these uprises, so also 
 with several depressions that have been noticed, though 
 these from their nature are generally less perceptible. Such 
 tracts of subsidence have been observed along the west 
 coast of Greenland, the southern coasts of the United States, 
 and generally in the basin of the South Pacific. Whatever 
 the nature of these uprises or depressions whether at the 
 rate of four or five feet a century, as in the case of Scandi- 
 navia, or with greater or less rapidity ; whether recent, like 
 those of Spitzbergen and Greenland, or ancient, like those 
 of our own country they all belong to the same class of 
 phenomena, and are evidently the result of some great but 
 unknown law. Physicists have attempted an explanation, 
 some attributing the phenomena to oscillations of the hypo- 
 thetical molten interior, and others to secular expansions 
 and contractions of portions of the crust, as arising from 
 changes in the axis of rotation and centre of gravity. In 
 either case the oscillation of a few thousand feet is insigni- 
 ficant as compared with the diameter of the globe ; and as 
 elevation in one region seems to be counterbalanced by sub- 
 sidence in another, the general relations of our planet may 
 be regarded as standing for ages unaffected by the amount 
 of its superficial changes. 
 
 Insignificant, however, as ' may be the effect of such 
 oscillations upon the general relations of the earth, they are 
 all-important to the climate, and consequently to the flora 
 
60 VULCANISM ITS NATURE AND FUNCTION. 
 
 and fauna of the region in which they occur. A few hun- 
 dred feet of elevation or depression in the higher latitudes 
 of the north is tantamount to a loss of several degrees of 
 annual temperature ; and we can readily conceive what 
 would be the effect of another thousand feet of uprise on 
 the existing flora and fauna of Siberia, Greenland, or the 
 Arctic islands of America. In fine, it requires no great 
 stretch of the imagination to conceive to what extent the 
 climatology of the globe may be influenced by a system of 
 extensive elevations and depressions of its surface ; how 
 the cold and warm currents of the ocean might be diverted; 
 how one region might be elevated so as to be permanently 
 enveloped in snow and ice, while another in the same lati- 
 tude might lie at so low a level as to enjoy the amenities 
 of a temperate climate. On the whole, whatever may be 
 the origin of these slow and gradual crust-motions, we be- 
 hold in them a system by which the distribution of sea and 
 land is changed, by which climate is modified, and conse- 
 quently by which the plant -life and animal -life of our 
 planet is materially affected. 
 
 Such are the three great manifestations of vulcanism 
 the volcano, the earthquake, and the gradual crust-motion; 
 and though their origin be obscure, the human mind sel- 
 dom rests satisfied with mere description, but must attempt 
 a solution of cause and origin. There are two principal 
 hypotheses that have been advanced to account for vulcanic 
 phenomena, and which may be respectively termed the 
 mechanical and the chemical. By the former, the whole 
 is resolved into an aboriginal igneous condition of the 
 earth's mass, on which, after the lapse of ages, a cooled and 
 rocky crust has been formed over a molten interior. To 
 oscillations in this molten interior, to its reactions upon 
 the crust, to the cavernous structure of the crust, and to 
 
THEORIES OF VOLCANIC ACTION. 61 
 
 chinks and fissures that admit the percolation of water 
 down to the incandescent mass, are ascribed the tremors 
 and convulsions of the earthquake and the sudden explo- 
 sions of the volcano. By the latter hypothesis it is pre- 
 sumed that the solid crust contains abundance of metallic 
 elements, such as potassium, sodium, calcium, magnesium, 
 and the like, and that the percolating waters coming in 
 contact with these produce instantaneous combinations, 
 which result in uncontrollable manifestations of heat, and 
 the conversion of these metals into their oxides potash, 
 soda, lime, magnesia, &c. which enter largely into the 
 composition of the rock-matter ejected at the surface. Such 
 is a brief and general view of the two leading hypotheses 
 that have been advanced to account for vulcanic pheno- 
 mena. The adherents of the former question the presence 
 of these metallic elements in such abundance as to produce 
 such gigantic results, and point to the universality of vol- 
 canic action and the uniformity of its products as evidences 
 of its arising from the same great interior source. The 
 adherents of the latter contend for a system of action and 
 reaction, without which the globe would gradually lose its 
 supposed interior heat, and become so cool that in process 
 of time volcanic action would cease a result incompatible 
 with the maintenance of a diversified and habitable surface. 
 According to the mechanical theory, say they, the interior 
 heat must be gradually declining, and must finally come to 
 an end ; but according to the chemical, there is a round of 
 incessant action and reaction, a system of compensation 
 and endurance which accords with the other ordainings of 
 the universe. This is not the place to do more than merely 
 allude to these contending views, our object in these sketches 
 being rather to explain what is known than to discuss 
 what is questionable. 
 
 But whatever be the origin of vulcanic force, we see it 
 
62 VULCANISM ITS NATURE AND FUNCTION. 
 
 abundantly manifested in various regions of the globe 
 here in isolated centres like those of the Mediterranean 
 and Iceland, there in linear directions like the Andes, and 
 occasionally over wide areas like the Indian and Chinese 
 Archipelagoes. At the present moment there are between 
 three and four hundred active volcanoes (with as many 
 more in a dormant or semi-extinct state), chiefly fringing, 
 as it were, the Pacific or scattered over its surface. In the 
 latter instance they appear in insular centres, as in the 
 Sandwich and other groups ; in the former they occur in 
 great lines, as in the Andean, Mexican, and Columbian 
 Mountains, the Aleutian Islands, Kamtschatka, Japan, the 
 Philippine Islands, and the Indian Archipelago. Com- 
 pared with these the display of volcanic energy in other 
 regions is insignificant ; while over immense tracts like 
 the north of Asia and Europe, and the Atlantic slopes of 
 both Americas, the internal forces have been still and sta- 
 tionary for ages. We know from the mountain-ranges of 
 these regions that the forces once were there ; we see their 
 effects in the primary granitic mountains, in the secondary 
 hills of basalt and greenstone, and in the tertiary domes of 
 trachytic lava;* but of the law that has regulated this shift- 
 ing from area to area, and now restricted it to its present 
 
 * It may be of use to the general reader to mention that the principal 
 rocks in recent volcanic hills are lavas of various aspect and compact- 
 ness ; tufas, or consolidated cindery matters ; pumice, or light vesicular 
 lava; obsidians, of glassy texture; and trachytes, or granular-crystalline 
 masses : and that their differences depend partly on chemical composi- 
 tion, but chiefly on the rapidity with which they have been cooled 
 rapid cooling producing a compact glassy texture, and slow cooling the 
 reverse. The rocks of the secondary hills, on the other hand, though 
 originally consisting of the same volcanic ejections, are now converted 
 into crystalline greenstones, basalts, felstones, the softer trap-tuffs, and 
 amygdaloid*, or those whose original vesicles have got filled with almond- 
 shaped infiltrations of lime-spar, agate, and other minerals. In the older 
 mountains the conversions are still more complete, and highly crystalline 
 granites, syenites, and porphyries are the prevailing compounds. 
 
PERMANENCE OF VOLCANIC ACTION. 63 
 
 centres, we know next to nothing, and are merely on the 
 threshold of the inquiry. 
 
 Little, however, as we know either of the cause or of 
 the course of vulcanism, we can readily perceive its func- 
 tion, and behold in it one of the great means by which the 
 crust of the globe is held in equilibrium, and by which the 
 diversity and variety of its surface is maintained. Were 
 there no adequate force acting from within, the powers of 
 waste and degradation from without would in time reduce 
 the surface to one dreary monotony of level, incompatible 
 with that diversity of condition and of life which appears 
 to be one of the great aims of creation. But just as the 
 meteoric and aqueous forces wear and waste from without, 
 so the vulcanic renovate and upheave from within; and 
 thus the rocky crust is held in perfect equipoise, and its 
 surface diversified by all that irregularity of hill and val- 
 ley, of table-land and plain, which is indispensable to variety 
 -in the plant-life and animal-life by which it is adorned. 
 Wherever large expanses of the earth's surface, like the 
 prairies and pampas of America, are characterised by same- 
 ness of condition, there is a consequent want, of variety in 
 their vegetable and animal existences ; but as the great de- 
 sign of Creation seems to be variety in space as well as 
 variety in time, this uniformity of surface is incessantly 
 broken up by the operations of the earthquake and volcano. 
 Locally disastrous as may be the throes of the one or the 
 discharges of the other, we thus behold in each a necessary 
 part of the world's mechanism, and powerful in proportion 
 to the work it has to accomplish. 
 
 It has been frequently discussed, and with some is still 
 a question, whether this power of internal vulcanism be 
 steadfast or declining, and whether it did not manifest 
 itself with greater intensity during the earlier geological 
 periods? Locally we may perceive that it has ceased in 
 
N 
 
 64 VULCANISM ITS NATUKE AND FUNCTION. 
 
 some areas, and in others seems gradually declining ; but 
 at the same time we behold it breaking forth in new areas, 
 and on a survey of the whole world, see no reason to con- 
 clude that it is now either less extensive in its distribution 
 or diminishing in its intensity. The Andes, through whose 
 extreme length the earthquake and volcano are ceaselessly 
 active, are as gigantic as the Himalaya, where they have 
 long since ceased to exist ; the Mexican Cordilleras broader 
 and loftier than the Alps ; the Alps more imposing than 
 the older Pyrenees ; and the Pyrenees as decided in their 
 character as the primitive ranges of Scandinavia. The 
 cincture of volcanic action that girdles the Pacific (in the 
 Andes, Californian Sierras, Aleutian Isles, Kamtschatka, 
 Japan, Philippine Islands, the Indian Archipelago, and 
 New Zealand, to say nothing of the groups that stud its 
 bosom) is as gigantic as any axis or area geology has re- 
 vealed,* while the individual discharges and irruptions are 
 unexcelled by those of any former period : and in corrobora- 
 tion of this we need only point to the lava streams of Etna, 
 from twenty to forty miles in length to those of Iceland, full 
 fifty miles in length, by twelve to fifteen in width ; or to 
 
 * In absence of a map the following arrangement may convey to the 
 reader a general idea of the disposition of these volcanic lines and centres. 
 1. Along the borders of the Pacific : Throughout the entire length of 
 the Andes from Tierra del Fuego northwards ; in Central America ; 
 Mexico ; Oregon ; the Aleutian Islands ; Kamtschatkan peninsula ; the 
 Kuriles ; Japan group ; Philippines ; East India Islands ; New Guinea ; 
 East coast of Australia and New Zealand. 2. Over the Pacific : In the 
 Sandwich Islands ; Friendly Islands ; Fejees ; Santa Cruz group ; New 
 Hebrides ; and the Ladrones. 3. Over the seas that lie between the northern 
 and southern continents, and adjacent regions ; West India Islands ; the 
 Mediterranean and its borders ; the southern borders of the Caspian and 
 eastward ; and the East Indian Archipelago as lying between Asia and 
 Australia. 4. In the Indian Ocean ; Bourbon and the Mauritius ; 
 Comoro group ; and Madagascar. 5. In the A tla-ntic : St Helena ; the 
 Cape Verdes ; Canaries ; Madeira ; Azores ; and Iceland. The interiors 
 of the great continental masses both in the old and new worlds are still 
 and quiescent. 
 
CONTRASTED WITH OTHER FORCES. 65 
 
 those of the Sandwich Islands, nearly seventy in length, 
 and of varying width and thickness, according to the 
 nature of the declivity down which they have flowed. On 
 the whole, there seems no ground for the supposition that 
 vulcanism is now either less extensive or less energetic than 
 in former ages. All that geology perceives is that it has 
 shifted from area to area ; that the old mountains where 
 it once reigned are long since cold and silent; that the 
 secondary hills bear but few traces of its presence; and 
 that now it upheaves along other lines and convulses from 
 newer centres. 
 
 That in vulcanism, as in other cosmical forces, there 
 must be a law determining both its time and mode of oper- 
 ation is sufficiently* obvious ; but in the mean time that law 
 lies altogether beyond the indications of science, and we 
 must content ourselves with mere descriptions of pheno- 
 mena and explanations of function. What the cause of 
 volcanic energy 1 what the periodicity of its discharges 1 
 what the times and directions of earthquake convulsions 1 
 and what the law which regulates the shifting of vulcan- 
 ism from centres that were once disturbed to newer areas ? 
 are questions to which science can give no satisfactory 
 answer, and generations may pass before even the way to a 
 solution is indicated. What we want is, first, a more minute 
 investigation of the products of volcanoes, that it may lead 
 to a knowledge of the decompositions taking place within 
 the earth's interior ; second, observations as to the connec- 
 tion between earthquake throes and volcanic discharges; 
 third, a record of the times and directions of earthquake 
 convulsions ; and, fourthly, an accurate series of tabulations 
 and maps to assist us in our deductions. All this is little 
 more than merely beginning to be done. Chemistry and 
 physics have only recently been directed to the subject; 
 and Seismology or Seismography (the science of earth-shocks) 
 
66 VULCANISM ITS NATURE AND FUNCTION. 
 
 is a study as it were but of yesterday.* Till substantial 
 progress has been made in this direction, and sufficient facts 
 for generalisation collected, it were idle to speculate, and 
 waste of time to surmise. 
 
 Such is a brief, and we trust not unintelligible sketch of 
 that Vulcanicity or internal heat-force which is incessantly 
 reacting upon the rocky crust we inhabit. Than the earth- 
 quake, volcano, and great crust-pulsation, we have no higher 
 manifestations of natural force ; no phenomena before whose 
 power man's weakness becomes more apparent. There are, 
 no doubt, other terrific agencies in nature the ocean when 
 lashed into fury by storms, the flooded and headlong river, 
 the hurricane, and the thunderstorm. Man, however, learns 
 to brave and battle with these. The hardy islander dares 
 the ocean-storm in his little skiff; civilised nations build 
 their piers and breakwaters that their fleets and navies 
 may ride behind them in defiance of the storm. Man dams 
 and diverts the river-current, restrains it within bounds, 
 or even turns it to account as the moving power of his 
 machinery. By strength and weight of material he can re- 
 sist the fiercest sweep of the wind-blast ; or if need be, can 
 yoke it to his wheels submissive and serviceable. He even 
 toys with the thunder, and brings the lightning down from 
 the storm-cloud. But before the shock of the earthquake 
 and the throes of the volcano, man savage or civilised 
 shrinks altogether abject and helpless. With them, how- 
 ever frequently they may occur, he never becomes familiar. 
 The earth, with which all his ideas of stability are associated, 
 rocks and reels beneath him his proudest cities become 
 an instantaneous mass of ruin and rubbish ; himself falls 
 prostrate, or if he flees, he flees only to accelerate his fate. 
 
 * See the ' Seismology/ and ' Seismographic Maps/ of the Messrs Mal- 
 let, of Dublin. 1861. 
 
CONTRASTED WITH OTHER FORCES. 67 
 
 The volcano casts forth its scorching showers of scoriae and 
 ashes, his pastures and vineyards are utterly consumed, and 
 his homesteads and villages like Pompeii and Herculaneum 
 are buried, so that for centuries their very places are un- 
 known. Or the red river of lava spreads slowly and irre- 
 sistibly down the mountain-side, crushing and consuming 
 the forest-growth like stubble, damming and diverting river- 
 courses, engulfing villas and towns, and converting the 
 fair face of nature into a wilderness of blistery slag and 
 "the blackness of desolation." 
 
 Opposed to these terrific agencies, man stands utterly 
 impotent ; and alas for his ideas of this Scheme of Crea- 
 tion, if he cannot learn to associate them with its necessary 
 order and mechanism ! Exposed to incessant powers of 
 waste and degradation from without, the earth's crust is 
 only maintained in habitable equilibrium and variety of 
 surface by this power of vulcanism acting as incessantly 
 from within. As it now manifests itself by the three or 
 four hundred orifices known to geographers, so in all time 
 past have its manifestations been equally apparent now in 
 this region, now in that, now feebly, now with greater in- 
 tensity, fitful to all appearance, but obeying, we may rest 
 assured, some fixed and determinable law, could we only 
 grasp the multifarious conditions associated with its expres- 
 sion. As at present, so during all the geological periods, 
 we find that it has been gradually elaborating hills and 
 mountain-ranges, upheaving and consolidating the sediments 
 of the sea-bottom, giving diversity of surface to areas of 
 flat and uniform deposit, raising substances of utility from 
 inaccessible to accessible depths in the earth's crust, and 
 reticulating that stony fabric with lines and walls of injected 
 matter, which under the names of " dykes" and "faults" 
 restrain the percolation of its internal waters, and bring 
 them to the surface in thousands of living and refreshing 
 
68 VULCANISM ITS NATURE AND FUNCTION. 
 
 streams. The great diversity of animal and vegetable life 
 which now adorns this earth is clearly associated with its 
 diversity of surface, and this diversity of surface this 
 arrangement into hill and dale, into table-land and plain, 
 into island and continent, with all its varying accompani- 
 ments of wind and ocean-currents and climate is the direct 
 result of the earth's incessant vulcanicity. Unless then, 
 when considering the earthquake, volcano, and crust-motion, 
 we can learn to regard them as necessary portions of the 
 orderly mechanism of our planet, we are viewing them in 
 the feeblest light, and much as the cowering savage, who 
 sees in them only disorder and destruction, and the wrath 
 of his offended deities. And even where science cannot 
 pierce the veil, we may rest assured, in this as in other 
 arrangements of nature, that nothing is jarring, but that all, 
 however unintelligible to our finite comprehensions, is in 
 perfect harmony, and indispensable to the maintenance of 
 this wondrous world-plan 
 
 " All seeming discord, things not understood ; 
 All partial evil, universal good. " 
 
 
METAMOBPHISM, OK THE TKANSFOKMATIOKS 
 OF KOCK-MATTEK. 
 
 METAMORPHISM, DEFINITION OF THE TEEM ALL ROCK-MATTER 
 INCESSANTLY UNDERGOING INTERNAL CHANGE THROUGH PRES- 
 SURE, ATTRACTION OF COHESION, CHEMICAL ACTION, HEAT, MAG- 
 NETISM, CRYSTALLISATION, AND OTHER SIMILAR FORCES 
 ILLUSTRATIONS OF THESE RESPECTIVE FORCES AND THEIR MODES 
 OF ACTION THEIR EFFECTS MOST PERCEPTIBLE IN THE OLDER 
 ROCKS THE SO-CALLED METAMORPHIC ROCK-SYSTEMAPPARENT 
 OBLITERATION OF ITS FOSSILS GRADUAL DETECTION OF THESE IN 
 PECULIAR LOCALITIES RESOLUTION OF THE SYSTEM INTO MINOR 
 SECTIONS AND CHRONOLOGICAL ORDER INCONCEIVABLE AMOUNT 
 OF TIME IMPLIED IN THE DEPOSITION AND SUBSEQUENT TRANS- 
 FORMATIONS OF THE METAMORPHIC SYSTEM HOW TO DEAL 
 WITH IT AS A PART OF WORLD-HISTORY ITS CONVENIENCE AS 
 A PROVISIONAL DESIGNATION. 
 
 IT has been already explained that all the substances com- 
 posing the earth's crust, from the most recent and super- 
 ficial soils, sands, muds, and gravels, down to the oldest and 
 deepest slates and schists, are known as rocks and rock-forma- 
 tions. It has also been shown that all these rock-matters 
 are undergoing incessant changes, being weathered and worn 
 from the old hills, borne onwards by streams and rivers, 
 laid down as sediments in lakes and seas and estuaries, and 
 again upheaved by vulcanic agency as the solid strata of 
 newer continents. In this long and ceaseless round they are 
 disintegrated and dissolved, reconstructed and consolidated, 
 and it is to the varied processes of reconstruction and consoli- 
 dation that we would here direct attention. Every substance > 
 
70 TRANSFORMATIONS OF ROCK-MATTER. 
 
 the moment it is laid down as sediment or discharged from 
 the crater of a volcano, "begins to suffer change and transfor- 
 mation. The attraction of cohesion, pressure, the percolation 
 of chemical solutions, heat, magnetic currents, crystallisa- 
 tion, and the like, are all more or less altering its internal 
 texture, and in the long-run its external aspect or structure. 
 In course of time, and under the operation of these forces, 
 the softest mud "becomes compacted into shale, sand into 
 sandstone, gravel into conglomerate, peat-moss into coal, 
 and coral-growths into limestone ; and by a farther trans- 
 formation shales may become glistening clay-slates, sand- 
 stones quartzites, coals anthracites, and limestones sparkling 
 and. crystalline marbles. This kind of transformation, or 
 Metamorplnsm, as it is technically termed, forms one of the 
 most wonderful as it does one of the most difficult chapters 
 in geology, and it is to place it in as simple and intelligi- 
 ble a light as the nature of the subject will permit that we 
 attempt the present Sketch. Of course, it is not to be 
 expected that what is often a matter of doubt and difficulty 
 to the professed geologist can be made easy to the compre- 
 hension of the casual inquirer; but an indication of the 
 processes of metamorphism can be given, and such indi- 
 cation may lead to a more satisfactory conception of the 
 character and formation of rocks in general. 
 
 One of the most obvious agents in the re-formation of 
 disintegrated rock-matter is simple mechanical pressure. 
 As layer after layer of sedimentary matter (mud, clay, sand, 
 gravel, &c.) accumulates in seas and estuaries, the lower and 
 earlier are necessarily pressed upon by all those above them, 
 and thus they are gradually consolidated muds and clays 
 into shales, sands into sandstones, and gravels into conglo- 
 merates. This pressure at great depths must be enormous ; 
 and as it is incessant in its action, we can readily perceive 
 how rock-substances may be altered in their structure and 
 
PRESSURE AND CHEMICAL ACTION. 71 
 
 texture by this force alone. But during this mechanical 
 pressure chemical actions and reactions are perpetually 
 taking place in all rock-masses, and thus its effects are facili- 
 tated and rendered much more perceptible. A bed of peat, 
 for example, may be solidified by compression, but during 
 its chemical passage into coal it undergoes a process of 
 softening and bituminisation which enables mere pressure 
 to act with greater uniformity and effect. In the earth's 
 crust, therefore, wherever chemical transformations take 
 place, or heat is induced by chemical actions, mechanical 
 pressure will act with increased efficiency ; and as these are 
 almost everywhere present, we may regard the two combined 
 (that is, pressure and chemical action) as amongst the most 
 important agents in the metamorphism or transformation 
 of rock-matters. And those who have witnessed the effects 
 of the hydraulic press the conversion of the softest pulp 
 into a solid mass, and the loosest powder into a hard and 
 brittle stone can have little difficulty in conceiving the 
 myriad-fold greater result of thousands of feet of superin- 
 cumbent strata, and the continuance of their weight and 
 pressure for unknown ages. 
 
 But while all rock-substances are thus continually pressed 
 upon and transformed by those that lie above them, the in- 
 filtration of chemical solutions as well as chemical reactions 
 among the particles of their own mass are also materially 
 assisting in changing their composition and texture. The 
 loose shelly sand of the sea-shore is often cemented into a 
 compact conglomerate* by the percolation of rain-water, 
 which, dissolving the limy matter of the shells, diffuses it 
 
 * This " littoral concrete," as it has been lithologically termed, may be 
 witnessed among the sand-drifts, and along the shores of many parts of 
 the British Islands. Composed of sand, shells, and pebbles, it is often of 
 stony hardness, and might be mistaken for an older rock, were it not for 
 the imbedded shells, which are all recent, and to be found in the neigh- 
 bouring seas. 
 
72 TRANSFORMATIONS OP ROCK-MATTER. 
 
 through the mass, as a mortar to bind the incoherent par- 
 ticles into a solid rock. Every rock in the earth's crust 
 sedimentary and vulcanic is rendered more compact and 
 crystalline by this process of chemical infiltration. "Water 
 is ever permeating this outer shell, and thus solutions of 
 lime, silica, iron, and other mineral and metallic substances 
 are borne hither and thither here cementing sand and 
 gravel into grits and conglomerates, and there calcifying 
 a sandstone; here silicifying and hardening some earthy 
 limestone, and there converting volcanic dust and ashes into 
 stony tufas and amygdaloids. Besides simply cementing 
 and hardening the masses through which they percolate, 
 these solutions give rise to new chemical actions, by which 
 certain rocks are rendered more crystalline, and altogether 
 changed in their texture. A solution of silica, for example, 
 may permeate a porous sandstone, and by cementing to- 
 gether its particles render it merely harder and more com- 
 pact ; while a similar solution, in passing through an earthy 
 chalk, might form a chemical union with the mass, and 
 convert it into a tough and flinty chertstone. Those ac- 
 quainted with the changes that can be artificially induced 
 by chemical action, can have little difficulty in conceiving 
 how vast and complex the metamorphoses that may be 
 wrought within the rocky crust by the same agency, and all 
 the more that heat and moisture are there ever present to 
 facilitate its operations. And even where the changes are 
 slow and gradual so slow as to be almost imperceptible 
 we may rest assured they are still going forward, and only 
 require time for their perfect development. The recent 
 rocks must necessarily have suffered less metamorphism 
 than the ancient, but still the time and fitting conditions 
 will come when the loose sand will be converted into 
 sandstone, and the sandstone, by further change, into 
 quartzite; the peat be changed into lignite, the lignite 
 
SUBTERRANEAN HEAT. 73 
 
 into coal, and the bituminous coal into a hard and nameless 
 anthracite. 
 
 But whatever the amount of rock-change brought about 
 by chemical agency, it is far less noticeable than that in- 
 duced by the operations of subterranean heat, whether 
 acting in the dry way, as in volcanoes, or in the wet, as in 
 hot springs and vaporiform exhalations. Whatever be the 
 source of volcanic heat, its effect by contact on all the 
 stratified rocks is at once marked and decisive. Sand- 
 stones are frequently converted into crystalline quartzites, 
 shales baked into splintery porcellanite and porcelain jas- 
 per, and bituminous coals changed into coke-like anthracites. 
 We every day witness the effects of dry heat in our brick- 
 kilns, coke-ovens, glass-houses, and iron-furnaces ; and if 
 the effect of such temporary heat be to melt and bake and 
 calcine, how much more the results of those subterranean 
 fires, that may continue to operate in certain areas unabated 
 for ages ! In the earth's crust, then, we may rest assured 
 that volcanic heat has effected, and is still effecting, exten- 
 sive metamorphism in all rock-masses, and that those lying 
 at great depths and under vast pressure will be affected very 
 differently from those occurring near the surface. But be- 
 yond this contact with dry heat there is the permeation of 
 heated water and vapours, which greatly facilitate the dis- 
 solution and recombination of mineral matters. As the tem- 
 perature of the crust increases at the rate of one degree 
 Fahr. for every 60 or 65 feet of descent, the transforming 
 effect of this heat at the depth of a few miles must be 
 enormous ; and we can readily conceive (though we cannot 
 witness the operation) how ordinary strata may be con- 
 verted into crystalline schists and igneous rocks, as the 
 traps and lavas, undergo a process of re- crystallisation, and 
 assume the character of granites. Heat, in whatever form 
 it operates, is, indeed, the great transformer of mineral 
 
74 TRANSFORMATIONS OF ROCK-MATTER. 
 
 matter here baking and hardening, there calcining and 
 melting ; here inducing crystallisation, and there, in com- 
 bination with other forces, filling veins with veinstuffs and 
 metallic ores. 
 
 In connection with this deep-seated heat, we may also 
 believe that magnetic currents and crystallisation (to what- 
 ever force or forces it may be due) are also effecting a 
 marked metamorphism on all the older and deeper-seated 
 rocks. The earth is in fact a great magnet, through whose 
 exterior crust currents of varying intensity are ever passing ; 
 and these, we may rest assured, are actively instrumental in 
 altering the molecular arrangement of rock-masses, and con- 
 ferring upon them not only new textures, but also new 
 structures, such as cleavage, crumpling, foliation, and other 
 peculiarities which distinguish the slates and schists of the 
 older formations. Experiment has tried to imitate this 
 mode of metamorphism by passing galvanic currents through 
 masses of moistened pottery clay, and the result was re- 
 arrangement of the particles so as to produce cleavage, or 
 fissility, such as occurs in roofing-slate, and at the same 
 time a glistening and semi-crystalline texture. Taken in 
 connection with heat, these subtle forces of chemistry, 
 magnetism, and crystallisation, are obviously important 
 modifiers of mineral and metallic matters ; and thus, among 
 the oldest rocks, which have been the longest subjected to 
 their influence, we find crystallisation, cleavage, foliation, 
 and kindred phenomena in their greatest intensity. It is 
 to these older rocks that the term METAMORPHIC is gene- 
 rally applied ; and though all rock-matters are continually 
 undergoing metamorphism, and in some localities intensely 
 so, yet these old semi -crystalline and highly -altered slates 
 and schists are so intimately associated in character and 
 position that they have been grouped into a system the 
 " METAMORPHIC SYSTEM " of Systematic Geology. 
 
PRINCIPAL AGENTS CONCERNED IN. 75 
 
 Summing up our knowledge of this metamorphism or 
 transformation of mineral matter by which chalk, for 
 instance, can be changed into crystalline marble, and clay 
 into glistening roofing-slate it may be safely affirmed that 
 the following are the principal agents concerned in its 
 production, even though we may not be always able to 
 determine their precise modes of operation : 1. Heat by 
 contact, as when an igneous mass, like lava, indurates, 
 crystallises, or otherwise changes the strata over or through 
 which it passes. 2. Heat by transmission, conduction, or 
 absorption, which may also produce metamorphism, accord- 
 ing to the temperature of the heated mass, the continu- 
 ance of the heat, and the conducting power of the strata 
 affected. 3. Heat by permeation of liot water, steam, and 
 other vapours, all of which, at great depths, may produce 
 vast changes among the strata, when it is recollected that 
 steam under sufficient pressure may acquire the temperature 
 of molten lava. 4. Electric and galvanic currents in the 
 earth's crust, which may, as the experiments of Mr "W. Fox 
 and Mr R. Hunt suggest (passing galvanic currents through 
 masses of moistened pottery clay), produce cleavage and 
 semi -crystalline arrangement of particles. 5. Chemical 
 actions and reactions, which, both in the dry and moist 
 way, are incessantly producing atomic change, and all the 
 more readily when aided by an increasing temperature 
 among the deeper-seated strata. 6. Mechanical -pressure, 
 produced by the mere weight of superincumbent strata, and 
 which is obviously concerned in the solidifying, compact- 
 ing, and hardening of all rock-matter, whether belonging 
 to the superficial or to the deeper-seated formations. 7. 
 New molecular arrangement by pressure and motion a 
 silent but efficient agent of change, as yet little under- 
 stood, but capable of producing curious alterations in inter- 
 nal structure, especially when accompanied by heat, as we 
 
76 TRANSFORMATIONS OF ROCK-MATTER. 
 
 daily see in the manufacture of the metals, glass, and earth- 
 enware. Such, we repeat, are the more general and likely- 
 causes of rock-metamorphism ; and as it is possible that 
 several of these may be operating within the same locality 
 at the same time, the reader will perceive that no hypo- 
 thesis that limits itself to any one agent can be accepted 
 as sufficient and satisfactory. 
 
 It has been already stated, that while every stratum 
 or portion of a stratum, every formation or portion of a 
 formation, may undergo metamorphism, it was to the older 
 and deeper-seated slates and schists that the term Meta- 
 morphic was more especially applied it being chiefly 
 among these that mineral transformations were to be wit- 
 nessed in their greatest intensity. It is true that in many 
 secondary mountains, such as the Alps and Apennines, the 
 stratified rocks are often highly metamorphosed ; but this 
 transformation is for the most part partial, some localities 
 remaining little affected, and having all their fossils distinct 
 and legible. Near one centre of vulcanic energy the shales 
 may be converted into dark glistening schists and the 
 limestones into crystalline marbles, while in another cen- 
 tre, and only a few miles distant, the shales and limestones 
 may retain their original sedimentary aspect. Among the 
 primary formations, on the other hand, the metamorphism 
 is general, and whole mountain-ranges and vast tracts of 
 country, like the Scottish Highlands and Scandinavia, are 
 entirely composed of crystalline slates and schists the 
 clay-slates, mica-schists, chlorite-schists, gneisses, quartzites, 
 marbles, and serpentines of the mineralogist. Among 
 these rocks stratification is indistinct, fossils are obliterated, 
 and the whole succession is massed into one enormous 
 thickness of unknown origin and antiquity. Under this 
 view these rocks have been successively regarded as 
 
SO-CALLED " METAMORPHIC" SYSTEM. 77 
 
 " Primary," "Metamorphic," "Azoic," and "Hypozoic,"* or, 
 in other words, as marking the earliest stages of world- 
 history, and "before life had "begun to make its appearance 
 on our planet. 
 
 This view, however, like many others of the earlier 
 geologists, has had to give way to more extended research 
 and newer discovery. Even during the time of the Ger- 
 man geologist Werner, a large portion of these primary 
 strata was found to be partially fossiliferous, and separated 
 under the term " Transition," as indicating the passage of 
 the world from an uninhabitable to a habitable state. In 
 our own time these Transition rocks (as will be more fully 
 explained in a subsequent sketch) have been subdivided 
 into " Silurian " and " Cambrian " systems, both of which 
 have yielded abundant forms of life; and still more re- 
 cently, in the schists and serpentines of the St Lawrence 
 the equivalents of the old gnarled gneiss-rocks of Scotland 
 and Norway traces of lowly life have been discovered, this 
 giving rise to the " Laurentian " system the oldest or 
 earliest strata in which fossils have yet been detected. Or, 
 tabulating the progress, we have first the PRIMARY of the 
 earlier geologists resolved into Transition and Metamor- 
 phic ; secondly, the TRANSITION resolved into Silurian and 
 Cambrian; and, lastly, the METAMORPHIC resolved into 
 Laurentian and Older Crystalline Schists ; thus 
 
 ( TRANSITION. J SILURIAN SYSTEM. 
 PRIMARY. I CAMBRIAN 
 
 I METAMORPHIC. [ J^UKENTIAN 
 
 v, ( OLDER CRYSTALLINE SCHISTS. 
 
 Here, then, it is obvious that what has hitherto been espe- 
 cially regarded as the metamorphic system is merely a 
 
 * Primary, first or earliest formed ; Metamorphic, changed or trans- 
 formed in texture ; Azoic, without life, or destitute of fossil remains ; 
 w, under life, or lying beneath the fossiliferous formations. 
 
78 TRANSFORMATIONS OF ROCK-MATTER. 
 
 vast succession of stratified rocks of true sedimentary origin 
 like any of the later systems, but so altered "by mineral 
 transformation that it is only in localities where the meta- 
 morphism has been partial and less intense that evidence 
 of their aqueous and fossiliferous nature can possibly be 
 discovered. As the extensive and mountainous tracts in 
 which these schists occur have been but slenderly investi- 
 gated, subsequent research may yet discover other fossils, 
 and resolve the whole into definite and satisfactory life- 
 systems. And should such hopes be fulfilled, how incon- 
 ceivably exalted will our notions of the world's antiquity 
 become new aeons of life and physical activity extending 
 away into a past as vast perhaps in duration as all the 
 later ages that geology has revealed ! We can never hope 
 to read aright these earlier pages of world-history, but 
 passages here and there may be recovered, and from these 
 scattered hints we may obtain enough to convince that 
 then as now the physical agencies of nature were ever 
 active and subject to the same laws, and that Life too was 
 present as their accompaniment, though then merely com- 
 ing into view under the operation of a higher and more 
 complicated law of development. 
 
 How then, it may be asked, are we to deal, in a chrono- 
 logical point of view, with the metamorphic rocks in which 
 no fossils have been detected ? Shall we describe them as 
 altered Silurians, Cambrians, or Laurentians? or shall we 
 continue to regard them merely as metamorphic strata of 
 unknown age, till some organism has been discovered that 
 may lead to their identification 1 Where the stratigraphical 
 succession is evident, it may often be convenient to mark 
 them as Silurian, or Cambrian, or Laurentian ; but where 
 the succession is doubtful, and no trace of organism has 
 been discovered, it will be much safer still to retain them as 
 mere metamorphic strata. Much error, both in theory and 
 
USE OF THE TERM " METAMORPHIC." 79 
 
 practice, may arise from adopting an opposite course, while 
 no inconvenience can result from the use of the term " me- 
 tamorphic," which merely implies that the rocks under 
 review have suffered intense mineral change, but advances 
 no opinion as to their age or chronological co-ordination. 
 We might colour on our geological maps the schists of the 
 Scottish Highlands and Scandinavia, as Silurian, Cambrian, 
 or Laurentian, and support our views by many plausible 
 arguments, but nothing would be gained by such a course 
 which is not already secured by the term " metamorphic," 
 while the subsequent discovery of their real character would 
 only be embarrassed by these hypothetical distinctions. 
 Let us continue, then, to treat these old rocks simply as 
 " the metamorphic," labouring to reveal their true nature 
 by the discovery of unobliterated fossils, and encouraged by 
 the success which, within the last thirty years, has resolved 
 so much of them into Silurian, Cambrian, and Laurentian 
 life- systems. 
 
 Such is the nature of metamorphism, or that internal 
 mineral transformation to which all rock -matter in the 
 earth's crust is incessantly subjected. Pressure, heat, che- 
 mical action, and the other agents above alluded to, are con- 
 tinually solidifying, hardening, and crystallising; and no 
 sooner is a sediment laid down, or an igneous mass ejected, 
 than it begins to be operated upon by one or other of these 
 forces. Of course, the latest laid down will have suffered 
 less change than the older and deeper-seated ; hence it is 
 chiefly among the latter that metamorphism is to be seen in 
 its greatest intensity. It may happen in certain areas, such 
 as centres of vulcanic activity, that secondary strata may be 
 as much metamorphosed, or even more so, than any of the 
 primary ; but still such instances are exceptional, and it 
 may be safely asserted as a general rule that the older 
 
80 TRANSFORMATIONS OF ROCK-MATTER. 
 
 rocks have undergone the greatest amount-of metamorphism 
 or internal mineral transformation. So great, in many in- 
 stances, has this change been, that stratification is rendered 
 indistinct, fossils obliterated, new minerals evolved in the 
 mass, and the rocks rendered so crystalline and homogene- 
 ous that it is difficult to determine whether they are really 
 of sedimentary or of igneous origin. Normally speaking, 
 between the most recent and most ancient rocks there will 
 be every gradation of metamorphism, and it is to this pro- 
 cess that the geologist must learn mainly to ascribe the 
 different aspects and textures that prevail among the rock- 
 formations of the globe. The atmospheric, aqueous, and 
 igneous forces may destroy the rocks in one region and 
 re-form them in another, but metamorphism is the sure and 
 silent agency by which they are compressed, solidified, 
 crystallised, and converted into other and other aspects. 
 ~No rock be it shale, sandstone, limestone, coal, iron- 
 stone, lava, or greenstone remains for ever the same. It is 
 incessantly, however slowly, passing on to other and newer 
 aspects, and metamorphism is the great wizard-power by 
 which the transformations are effected. A sandstone, how- 
 ever soft and granular now, will in time, and under the fit- 
 ting conditions, be converted into a crystalline quartzite, an 
 earthy limestone into a saccharoid marble, a tender and 
 bituminous coal into a hard and nameless anthracite, a 
 porous lava into a close-grained greenstone or basalt, and 
 a greenstone itself, by farther change, into a large-grained 
 crystalline granite. When once the operations of metamor- 
 phism are fully understood, the geologist has a key to much 
 that is puzzling and perplexing in his science j and not till 
 the efficacy of these is everywhere admitted can he be said 
 to have adopted the right methods for the solution of his 
 problems. 
 
 As the oldest rocks have undergone the greatest amount 
 
ANTIQUITY OP THE METAMORPHIC SYSTEM. 81 
 
 of metamorphism, so it is among them that the geologist 
 often meets with his greatest doubts and difficulties. Defin- 
 ing them as the metamorphic, they were at one time regarded 
 as preceding the fossiliferous strata, and as marking a period 
 of the earth's history when life did not exist, and when, of 
 course, its reliquiae were not expected to be found in the 
 rocky strata. As research extended, fossils were here and 
 there .discovered, even in these metamorphic strata ; and 
 hence the necessity of arranging them (see Sketch No. 5) 
 according to this new evidence into "systems" and "for- 
 mations," as had been done with the younger and more 
 fossiliferous strata. But beyond the deepest in which traces 
 of life have been detected, there still lie vast masses of 
 crystalline and granite-looking schists unresolved, and ap- 
 parently unresolvable, and to such the designation " meta- 
 morphic " is still specially applicable, and may ever remain 
 so. In these we find no legible record of world-history : 
 nothing beyond the great facts that they are stratified rocks, 
 and must have been laid down in seas and estuaries like all 
 other sediments, and that millions of ages must have elapsed 
 during their slow conversion from silts and sands and 
 gravels to crystalline schists and granitoid masses. But 
 though this be the present state of geologic knowledge, we 
 dare not, looking at the progress of the past, presume that 
 further discoveries will not be effected. These old rocks 
 may yet tell their tale of life just as the Laurentian and Cam- 
 brian have done it before them ; for, carry our researches 
 backward as we may, we perceive no traces of a beginning, 
 any more than in the existing operations of nature we see 
 indications of an end. 
 
 Once more : let it be clearly understood that metamor- 
 phism is simply internal mineral change ; that under pres- 
 sure, heat, chemical action, and other kindred forces, all 
 rock-matter in the earth's crust is incessantly undergoing 
 
 F 
 
82 TRANSFORMATIONS OF ROCK-MATTER. 
 
 such transformations ; and that while this crust is alter- 
 nately wasted and reconstructed by the agents described in 
 Sketch No. 2, it is mainly from metamorphism its rocks 
 receive these peculiarities of texture and structure that 
 confer upon them their distinguishing characteristics and 
 economic importance. 
 
THE PEIMAEY PERIODS. 
 
 OLDER AND YOUNGER PORTIONS OF THE EARTH'S CRUST THESE 
 REPRESENTED BY PERIODS OF TIME OR SYSTEMS OF STRATA 
 TECHNICAL ARRANGEMENT OF THESE PERIODS AND SYSTEMS THE 
 PRIMARY OR EARLIEST YET KNOWN, EMBRACING THE LAURENTIAN, 
 
 CAMBRIAN, AND SILURIAN COMPOSITION AND DISTRIBUTION OF 
 
 THESE RESPECTIVE SYSTEMS THEIR CHARACTERISTIC ROCKS AND 
 FOSSILS GENERAL PAUCITY OF LIFE ADVANCE DURING THE 
 SILURIAN CYCLE OF CRYPTOGAMIC PLANTS AND INVERTEBRATE 
 ANIMALS GEOGRAPHICAL ASPECTS OF THE PRIMARY PERIODS 
 INTEREST ATTACHED TO THEM AS THE DAWN OF WORLD - 
 HISTORY. 
 
 NOTHING can be clearer than this : if the higher and more 
 exposed portions of the earth be continuously wasted and 
 worn down, and the rock-material so wasted be as continu- 
 ously deposited in the receptacles of lakes and estuaries, 
 the older deposits (or formations, if you prefer to call 
 them) will be the deeper, and the newer will be arranged 
 in order of succession above them. Or put it in this 
 way: if the sediments of lakes and seas be gradually 
 converted into solid strata, and now and again upheaved 
 into dry land by vulcanic forces, the oldest, generally 
 speaking, will be the most consolidated and altered. Or 
 again, if the sediments of lakes and seas contain less or 
 more of the remains of plants and animals that have been 
 either drifted from the land or entombed in the areas where 
 they flourished, then the latest enclosed remains will be 
 
84 THE PRIMARY PERIODS. 
 
 the least altered and most resemble those still living in 
 the district. These propositions are so evident that it 
 would be little else than waste of time to attempt a more 
 detailed explanation. 
 
 "We have, then, in the crust of the earth some formations 
 very recent and others very ancient so recent that the 
 formative processes are still in action, and so ancient that 
 it requires all the appliances of modern science to say how 
 they were formed, and to determine the nature of the fossil 
 organisms they contain. The great plain of China and the 
 delta of the Mississippi, for instance, are of recent growth, 
 and indeed still in course of accumulation ; and by a parity 
 of reasoning we may readily perceive that the prairies of 
 North America and the pampas of South America, though 
 somewhat older, are still of comparatively recent formation. 
 Everything connected with these accumulations mineral 
 composition or imbedded organisms has an air of recent- 
 ness about it, and is readily intelligible ; but it is different 
 with the sandstones and limestones that lie beneath, whose 
 structure has been altered, and whose fossils have been 
 mineralised and rendered obscure. These sandstones and 
 shales and limestones were no doubt at one time loose sands 
 and clays and calcareous muds, but pressure, chemical ac- 
 tion, and other metamorphic forces, continued through long 
 ages, have converted them into solid strata, and this conver- 
 sion has been intensified, for the most part, according to 
 their relative dates. As with the stratified or sedimentary 
 formations, so also with the igneous. Such hills as Hecla, 
 Etna, and Teneriffe readily reveal their history; but the 
 Alps, the Pyrenees, and the Grampians, whose internal 
 fires have been long since extinguished, whose rocks have 
 become more crystalline, whose heights have been repeatedly 
 beneath the waters, and from which all the loose volcanic 
 matters have been washed and worn away, present a very 
 
OLDER AND YOUNGER FORMATIONS. 85 
 
 different aspect, and require all the ingenuity of science to 
 interpret their history. 
 
 This relative antiquity of rock-deposits may be still more 
 clearly shown by the formations of our own islands. The 
 carse-lands of the Tay and Forth and the fens of Lincoln- 
 shire are recent alluvia, and younger than the blue clays 
 and gravels over which they are spread ; the stratified sands 
 and clays and gravels in the neighbourhood of London are 
 younger than the chalk and greensands that lie beneath ; 
 and these chalk-hills and greensands of Kent and Surrey 
 are newer than the calcareous sandstones and limestones of 
 Portland on which they repose. Again, the oolites or roe- 
 stones of Portland are younger than the underlying red 
 sandstones and marls of Cheshire, and these newer than 
 the coals and ironstones of Lancashire that are spread out 
 beneath. The coals of Lancashire, Northumberland, and 
 Fife are not so old as the underlying red sandstones and 
 flagstones of Forfarshire; and these again are much 
 younger than the still deeper slates and crystalline schists 
 of the Scottish Highlands. NOT is it superposition alone 
 that proves this relative antiquity. Mineral structure and 
 texture become more intensified with age j fossil organisms 
 become more obscure, and the further we descend in time 
 the wider the divergence from the genera and species that 
 now people the globe. Everything in the earth's crust 
 speaks to this relative antiquity to this old, older, oldest ; 
 and it is the object of the present Sketch to describe the 
 earlier of these formations, and to depict, as far as Geology 
 can, the aspects of the periods when they were gradually 
 accumulating in the primeval waters. 
 
 Before entering on this description, however, it may 
 render matters more intelligible to state, and what indeed 
 has been already detailed in No. 1 of these Sketches, that 
 
86 THE PRIMARY PERIODS. 
 
 modern geologists arrange the earth's crust into the follow- 
 ing formations, or, referring to their fossils, into the follow- 
 ing life-periods and rock-systems : 
 
 Life-Periods. Rock-Systems. 
 
 ( Quaternary or Recent. 
 CAINOZOIC= RECENT LIFE. \ 
 
 ( Cretaceous or Chalk. 
 MESOZOIC=MIDDLE LIFE. \ Oolitic or Jurassic. 
 
 V Triassic or Upper New Red. 
 
 ("Permian or Lower New Red. 
 
 I Carboniferous or Coal System. 
 ?ALJ30ZOIC=ANCIENT LIFE. < OM Red Sandstoiie and Devonian. 
 
 [Silurian. 
 < Cambrian. 
 EOZOIC=DAWN LIFE. \ Laurentian. 
 
 This arrangement is, of course, temporary or provisional, 
 and may be altered as geologists "become more intimately 
 acquainted with rocks of other lands ; but in the mean time 
 it expresses our knowledge of the succession that prevails 
 among the stratified formations, and may be received as the 
 great chronological stages of the world's history. The tech- 
 nical terms are founded partly on mineral, partly on geo- 
 graphical, and partly on fossil distinctions, and may with 
 a little exertion become intelligible to the least scientific. 
 Thus " Cretaceous" and " Old Eed Sandstone" refer to the 
 most prevalent rocks in these systems ; "Laurentian" and 
 " Cambrian " to districts where the systems are largely 
 or typically displayed ; and " Cainozoic" and " Paleozoic" 
 to the comparative recentness and antiquity of the fossil 
 remains. A uniform system of nomenclature might have 
 been preferable, but human knowledge progresses by slow 
 degrees, and its terms and technicalities must be viewed 
 as mere provisional expedients towards this advancement. 
 Under the existing nomenclature geology has made bold 
 and rapid progress, and any attempt to revolutionise, unless 
 through the gradual increase of wider knowledge, would 
 
LAURENTIAN SYSTEM. 87 
 
 tend to obstruct rather than facilitate. It is to the oldest 
 of these so-called systems that we now direct attention ; to 
 the conditions under which they seem to have been de- 
 posited; and to the kind of life that appears to have 
 peopled the lands and waters of their respective periods. 
 We have classed them as the " Primary Periods/' because 
 there is really a greater similarity between their rocks and 
 fossils than there is between the rocks and fossils of any 
 subsequent periods ; because, so far as we know, their strata 
 are all truly marine deposits; and further, because their 
 fossil forms belong (speaking in general terms) to inverte- 
 brate types zoophytes, shell-fish, Crustacea, &c. and are 
 specially characterised by the absence of the vertebrates 
 the fishes, reptiles, birds, and mammals. 
 
 Beginning with the LAURENTIAN, which term has been 
 employed by Sir William Logan of the Canadian Geological 
 Survey, to designate the highly crystalline strata which 
 belong especially to the valley of the St Lawrence, and 
 constitute the great bulk of the Laurentide mountains, we 
 may take Sir William's own description of the rocks which 
 compose this oldest and deepest of sedimentary formations. 
 " The rocks of this system," he says, " are almost without 
 exception ancient sedimentary strata which have become 
 highly crystalline. They have been very much disturbed, 
 and form ranges of hills having a direction nearly north-east 
 and south-west, rising to the height of 2000 or 3000 feet, 
 and even higher. The rocks of this formation are the most 
 ancient known on the American continent, and correspond 
 probably to the oldest gneiss of Finland and Scandinavia, 
 and to some similar rocks in the north of Scotland. They 
 consist, in great part, of crystalline schists (chiefly gneissoid 
 or hornblende), associated with felspars, quartzites, and lime- 
 stones, and are largely broken up by granites, syenites, and 
 
88 THE PRIMARY PERIODS. 
 
 diorites, which form important intrusive masses. Among 
 the economic minerals of the formation, the ores of iron are 
 the most important, and are generally found associated with 
 limestones." Interpreting Sir "William's technicalities, it 
 may be stated for the comprehension of the general reader 
 that this old Laurentian formation, which is of vast thick- 
 ness (some 30,000 feet or thereby), consists essentially of 
 hard and crystalline strata like the gneiss, mica-schists, 
 quartz-rocks, and marbles of the Scottish Highlands, or more, 
 perhaps, like the still harder and more granitic -looking 
 schists of the Scandinavian mountains. There are no sand- 
 stones, or shales, or limestones in the proper sense of the term. 
 All these have been converted, long ages ago, by heat, pres- 
 sure, and chemical action, into sparkling crystalline rocks ; 
 lines and layers of stratification are obscure and often alto- 
 gether obliterated ; veins and eruptive masses are frequent ; 
 and altogether the whole formation wears the aspect of a 
 vast and venerable antiquity. 
 
 That the Laurentian system, like other stratified systems, 
 was deposited in the form of sands, gravels, clays, muds, 
 and other loose sediments, is beyond all question. Nature 
 has no other mode of procedure. What is wasted from the 
 lands is transferred to the waters ; nothing is lost. It may 
 change its form or place, but it is still in existence ; and this 
 incessant round of waste and reconstruction, as shown in a 
 former Sketch (No. 2), is the ordained order of the uni- 
 verse. What a wonderful metamorphism these primeval 
 sediments have undergone ! Not mud, nor sand, nor 
 gravel; not shale, nor sandstone, nor conglomerate; but 
 glistening slates and crystalline schists sandstones con- 
 verted into flinty quartz-rocks, and limestones into varie- 
 gated serpentines. And in the midst of all this metamor- 
 phism, the fossil organisms seem to have shared the same 
 fate ; for we cannot think of waters of deposition without 
 

 / 
 
 associating with them some forms of fcfe, hswerer lowly. 
 And yet, till within the last two years, the search for traces 
 of life in these primeval rocks was considered visionary, and 
 azoic and hypozoic, or " lifeless " and " under-all-life," were 
 the technicalities by which they were known. Nil desper- 
 andum, however, should be the geologist's motto, and espe- 
 cially of those who believe as we do that Life on this globe 
 was coeval with the stratified rocks, and that the conditions 
 which permitted the deposition of ordinary sediments must 
 have been favourable at the same time to the manifestation 
 of some form or other of vitality. And so it happens 
 that traces of lowly organisation have recently been detected 
 in these old Laurentian rocks in the serpentinous lime- 
 stones of Canada thus holding out the hope that the 
 primeval rocks of other regions will yet yield similar traces, 
 and prove that the earliest waters were tenanted by their 
 own forms of life, and were gladdened by the manifestations 
 of sentient existence. 
 
 Indeed similar organisms have already been detected in 
 the old (and probably contemporaneous) serpentines of 
 Ireland and marbles of Bohemia j and as one form of life 
 generally indicates the existence of another upon which it 
 preyed or was in turn preyed upon, we may shortly expect 
 important additions to this discovery. Even while we 
 write (1866), tracks and burrows, supposed to be those of 
 worms, have been discovered in a somewhat higher zone, and 
 described by Principal Dawson of Montreal. The organism 
 discovered, Eozoon Canadense, or "Dawn-animal" of Can- 
 ada," belongs to the lowest forms of life lower than the in- 
 fusory animalcules, and even still lower than the sponges. 
 It is one of the Foraminifera, mere animated specks, which 
 have nevertheless the power of secreting lime from the 
 waters, and enveloping themselves in elegant and variously- 
 formed cases. These calcareous cases are mere microscopic 
 
90 THE PRIMARY PERIODS. 
 
 points, and yet they are perforated by numerous pores 
 (foramina, hence the name of the order), through which 
 the creature procures its food and holds intercourse with 
 the outer world of waters. Individually minute, they live 
 in colonies, and only become conspicuous by their aggrega- 
 tions, which in the instance of the eozoon vary from a few 
 inches to a foot or two in diameter. The white calcareous 
 mud which covers so much of the Atlantic sea-bed is a 
 similar foraminiferal accumulation; so is the nummulitic 
 limestone which stretches eastward in a great zone through 
 Europe and Asia ; so also is a large proportion of the chalk- 
 hills of England ; and so backward in time through other 
 limestones, till we reach the oldest and earliest Laurentian 
 marble. With a little manipulation, the organisms constitut- 
 ing the existing sea-muds or the chalk are readily revealed ; 
 but the old eozoon has to be polished, cut into microscopic 
 slices, and treated with acids before the peculiarities of its 
 structure can be rendered intelligible. So great is the 
 change produced by the mineralisation of ages.* Strange 
 that the minutest of organisms should be capable of piling 
 up such stupendous rock-masses ; strange and suggestive 
 
 * We are aware some geologists have called in question the organic 
 nature of this Canadian eozoon regarding it merely as a peculiar mineral 
 structure mimetic of the organic, examples of such simulative structures 
 being well known in other formations. The majority of competent ob- 
 servers, however, maintain its organic nature ; and from a conversation 
 we had, in the autumn of 1865, with Principal Dawson of Montreal, who 
 has examined the rocks in situ, with their unobliterated lines of deposi- 
 tion and layers of organic growth (brought out more clearly by weather- 
 ing), we share the conviction that the Eozoon Canadense, whatever be 
 its zoological affinities, is of animal and not of mineral aggregation. To 
 the practised eye external appearances are often conclusive of organic 
 structure, and these, in the present case, had been observed and accepted 
 before the microscope was called into court to complete the evidence. 
 Those interested in this matter may refer to the papers by Dr Carpenter, 
 Professor King, and others, in the Journals of the Geological Society for 
 1865 and 1866. 
 
CAMBRIAN SYSTEM. 91 
 
 that the lowest forms of life should be the first and earliest 
 to reveal itself to the lenses of the palaeontologist ! 
 
 Turning next to the CAMBRIAN system, so termed by 
 Professor Sedgwick, because well developed in the region 
 of Wales (the ancient Cambria), we find it for the most 
 part made up of crystalline schists and slates, hard siliceous 
 grits, and altered limestones. Like the Laurentian, its strata, 
 have undergone extensive metamorphism or internal mineral 
 change, and like the Laurentian, too, it is frequently inter- 
 sected by veins and eruptive masses of granite, and fels- 
 pathic greenstone. On the whole, however, its sedimentary 
 character is much more apparent ; its micaceous schists are 
 interstratified with grits and sandstones, and its slates often 
 earthy and more distinctly laminated. Taking it in the 
 mass of its 15,000 or 20,000 feet, it has altogether a more 
 recent aspect than the Laurentian, and bears, not only in its 
 sandstones and shaly slates, but in its imbedded pebbles, 
 ripple-marks, and tracks of marine worms, more decided 
 evidence of its aqueous origin. Of course, like other forma- 
 tions, the Cambrian will vary in composition in different 
 regions, sometimes being more slaty, and at others more 
 schistose and crystalline ; but slaty beds, micaceous flag- 
 stones, gritty sandstones, and limestones more or less crys- 
 talline, may be taken as the normal aggregate. 
 
 When we turn to the fossils of the system we find them 
 also more numerous and intelligible than those of the Lauren- 
 tian, partly no doubt from the less metamorphism the beds 
 have undergone, but chiefly, perhaps, from that advancing 
 development of life we are accustomed to associate with the 
 newer and newer formations. At all events, instead of a 
 single organism, as in the Laurentian system, we now find, 
 if not a numerous, at least a fair array of zoophytes, echino- 
 derms, shell-fish, annelids, and Crustacea. The species are 
 
92 THE PRIMABY PERIODS. 
 
 certainly not the highest of their respective orders, neither 
 are they exactly the lowest ; but, making ample allowance 
 for the defects of our present information, it may "be safely 
 asserted that the fauna or animal-life of the Cambrian 
 period is altogether one of a lowly character, and that of the 
 flora or plant-life we know nothing beyond a few indistinct 
 impressions of algse or sea-weeds. Even the little we now 
 know of the Cambrian flora and fauna was altogether un- 
 known twenty years ago, and it is chiefly since 1846, and 
 more especially since 1859, that its fossiliferous character 
 has been fairly established. 
 
 Here then, as in the case of the Laurentian system, we 
 have a long period of the earth's history so long that 
 18,000 or 20,000 feet of sediment was accumulated in cer- 
 tain parts of the ocean and of which we know nothing 
 beyond what is recorded by these marine strata and the fos- 
 sils they contain. We have no glimpse of the land from 
 which these sediments were worn and wasted, yet there 
 must have been broad lands to supply this waste and rivers 
 to transport it. We are utterly ignorant of the plant-life 
 and animal-life if terrestrial life then existed by which 
 these lands were peopled. We know nothing of the dispo- 
 sition of sea and land as compared with the existing conti- 
 nents and seas. All that we clearly perceive is the exist- 
 ence of these sediment-receiving oceans, with their scattered 
 sea-weeds, zoophytes, shell-fish, and Crustacea, and only 
 faintly and at distant intervals their sandy and muddy 
 shores, in which annelids bored and left their burrows, and 
 over which Crustacea tracked and left their traces. Little 
 as this knowledge may seem, it is everything compared with 
 the beliefs of our ancestors; it is a great deal compared 
 with what was known even by the last generation ; and 
 it holds out the encouragement that another generation, 
 by following in the right path, will arrive at a fuller in- 
 
SILURIAN SYSTEM. 93 
 
 sight into the physical and vital aspects of this primary 
 period. 
 
 The last of the primary systems which form the subjects 
 of our Sketch is the SILURIAN, so named by Sir Roderick 
 Murchison, because well displayed and first examined by 
 him in that border country between England and Wales 
 which in ancient times was inhabited by the Silures. 
 Eocks of Silurian age have been found in almost every 
 region of the globe in Central and Northern Europe, largely 
 in both Americas, and in Australia and though they differ 
 much in their mineral composition, some being more crys- 
 talline and slaty than others, still on the whole thera is a 
 wonderful similarity among them, both in their lithological 
 and fossil aspects. Occasionally they are so metamorphosed 
 as to be undistinguishable from the crystalline schists of the 
 Cambrian and Laurentian; but, generally speaking, their 
 sedimentary character is abundantly apparent in the numer- 
 ous alternations of sandstones, slaty shales, and limestones, 
 and we see in these strata, with their fossil corals, shells, 
 and Crustacea, the clearest evidence of deep and wide- 
 spreading seas. Altogether the geological record becomes 
 more legible, and we can form some notion of the earth's 
 terraqueous conditions during the long and gradual deposi- 
 tion of the Silurian sediments. We say long and gradual 
 deposition, for in our own islands these strata are from 
 20,000 to 30,000 feet in thickness, embracing numerous 
 alternations of rock-material, and repeated removals and 
 renewals of genera and species of animals. 
 
 In these Silurian strata we perceive limestones formed of 
 coral-reefs and calcareous debris, slates, and slaty shales 
 arising from the deeper sea-muds, and sandstones, grits, and 
 conglomerates composed of the sands and pebbly shingle of 
 the shallower waters. Here and there through the mass we 
 
94 THE PRIMARY PERIODS. 
 
 find interstratified overflows of lava and showers of vol- 
 canic ashes, indicating that then, as now, the vulcanic forces 
 were active in their work of upheaval and eruption. How 
 wonderfully well these old rocks have retained the record 
 of their history ! Here shore-formed sandstones pattered 
 by crustacean feet and riddled with worm-burrows ; there 
 limestones formed of coral-growth and shell-debris in the 
 deeper waters : here slaty shales composed of the slimy 
 mud of the stiller depths, and replete with zoophytes ; and 
 there at intervals vast sheets of tuff and porphyry that 
 had been showered abroad as ashes or ejected as lava from 
 submarine volcanoes. Occasionally, in the pebbles of the 
 conglomerates, we catch glimpses of the kind of rocks that 
 formed the lands from which these sediments were trans- 
 ported, and from drifted clubmoss-like twigs in the shales 
 we know that these lands were clothed in some degree with 
 a vegetation, however lowly. 
 
 Such is the tale told of the Silurian epoch by its own rock- 
 formations ; but the history receives a deeper and livelier 
 interest when we come to consider the number and variety 
 of organisms imbedded throughout the system. It is true 
 that these are of lowly orders and wholly invertebrate, if 
 we except a few scattered fish-remains found in the very up- 
 permost beds, and by many regarded as belonging more pro- 
 perly to the Old Eed Sandstone ; but lowly as they are, they 
 occur in vast exuberance and variety, and mark a marvellous 
 progress in life-development compared with what is known 
 of the Cambrian and Laurentian. Sea-weeds and drifted 
 twigs and spores of clubmoss-like land-plants is all we 
 know of the Silurian flora ; but certain beds of anthracite 
 and anthracitous shales favour the idea that plant-life was 
 then more exuberant than has yet been detected. In its 
 fauna or animal -life we have foraminiferal organisms, 
 sponges, corals, polyzoa, or aggregate animals like the sea- 
 
SILURIAN SYSTEM. 95 
 
 mats and sea-pens (graptolites, &c.) ; shell-fish of every order, 
 bivalve and univalve, deep-sea and shore dwellers ; radiate 
 animals, like the encrinites and the star-fishes ; sea-worms in 
 their tracks and burrows ; and crustaceans, chiefly trilobites 
 and eurypterites, having some resemblance and affinity to 
 the existing limulus or king-crab. These organisms are not 
 found indiscriminately throughout the system, but vary in 
 number and distribution according to the kind of stratum 
 in which they are imbedded every zoophyte and shell-fish 
 preferring a certain kind of sea-bottom ; and according as 
 they occur in the lower, middle, or upper portion of the 
 system the upper being the more prolific and characterised 
 by the higher species. Numerous and varied as they are, 
 they are (with the exception of the obscure land -twigs) 
 exclusively marine ; and if we regard the uppermost beds, 
 with their fish-remains, as the base of the Old Eed Sand- 
 stone, they are entirely invertebrate,* and mark, so far as our 
 present evidence goes, the close of a long primary cycle 
 during which vitality was gradually evolving, in a fixed and 
 definite order, from lower to higher .manifestations. 
 
 As economic repositories these primary systems are, in 
 some regions, of considerable importance; less, however, 
 for their rock-products than for the metalliferous veins by 
 
 * The reader must guard against the idea that there are any sharp lines 
 of demarcation between the so-called Systems of geologists. The life of 
 certain estuaries and seas may no doubt be brought to a close by some 
 sudden catastrophe, but such breaks are merely local, and do not affect 
 the general life-arrangements of the globe. When we speak, therefore, of 
 the Silurian as " marking the close of a long invertebrate period," it is not 
 meant to be asserted that there were absolutely no fishes during the de- 
 position of the uppermost Silurians, but simply that the Primary Periods 
 as a -whole were characterised by their want of vertebrate remains, and that 
 the strata in which fish-remains do occur may be regarded, without detri- 
 ment to the science, either as uppermost Silurian or as lowermost Old 
 Red Sandstone. 
 
96 THE PRIMARY PERIODS. 
 
 which they are traversed. The vast bulk of their strata 
 "being gneisses and mica-schists, are little fitted for architec- 
 ture ; but their limestones, marbles, and serpentines are often 
 of great beauty and much sought after for ornamental pur- 
 poses ; while their fine-grained cleavable clay-slates afford 
 abundant material for roofing and other multifarious appli- 
 ances. Indeed, it is chiefly in these old metamorphic rocks 
 that serpentines/ variegated marbles, and roofing - slates 
 occur, the mineral transformations to which they have been 
 subjected giving to the former those varied shades of col- 
 ouring and figure, and to the latter that fissility or cleavage, 
 for which they are prized. But if the rocks of these systems 
 are of comparatively little value, their metalliferous veins 
 are rich and numerous gold, silver, tin, copper, antimony, 
 manganese, iron, and other metals being abundant in most 
 primary districts, either in the veins themselves or in the 
 debris that has been worn and washed from them during 
 the course of ages. These primary rocks constitute, indeed, 
 the bulk of all our older hill-ranges, and it is only in them 
 that the slow processes of chemical deposition have yet ela- 
 borated on a grand scale the metallic ores, and the vein- 
 stuffs with which these ores are usually associated. It is 
 true that veins and ores occur in some of the younger for- 
 mations, but not in the same variety, nor with the same 
 richness and persistence, as those that belong to the primary 
 and more highly metamorphic strata. Hence, it may be 
 remarked, the importance of geological investigation in 
 colonial and newly-discovered countries ; the determination 
 of their formations being tantamount to a declaration of 
 their mineral and metallic wealth, or, in other words, their 
 natural fitness for mechanical and commercial development. 
 
 Such are the great primary periods of world-history 
 the Laurentian, the Cambrian, and Silurian. Geologists 
 
THEIR ECONOMIC PRODUCTS. 97 
 
 may name and arrange them as they may, but the great fact 
 stands unquestioned, that according to our present know- 
 ledge they form the deepest or earliest of the fossiliferous 
 systems. Other fossiliferous strata still deeper and older 
 may be discovered as geology extends her survey of the 
 world's crust, but in the mean time such formations are 
 unknown. Whole systems of strata, deeper and older than 
 the Laurentian, may have been obliterated by metamorphic 
 changes, but such reasoning is altogether futile. In earth- 
 history as in human history we must make our chronologi- 
 cal arrangements according to our knowledge, and the 
 furthest verge to which we have pushed our investigations 
 must necessarily stand as the practical, though provisional, 
 commencement. And, after all, there is something so like 
 a beginning in these old Laurentian rocks, with their lowly 
 eozoa, that we feel, if not at the confines, at least nearing 
 the confines, of the possible in geological history. Observe, 
 it matters nothing to this history though the earth had 
 swung for untold cycles as an incandescent but gradu- 
 ally cooling mass. We have no means of inductively de- 
 termining such a condition, and we are bound in reason to 
 commence our history with the earliest operations we can 
 discover in the crust. The earliest of these operations is 
 the laying down of sediments as nature is now laying 
 down sediments ; and when we find these imbedding forms 
 among the very lowest of organised existence and nothing 
 higher, and find that in after ages the higher gradually 
 make their appearance in orderly succession, it would be 
 abandoning all logical guidance if we did not arrive at the 
 conviction that we were approaching, in these Laurentian 
 quartz-rocks, schists, and serpentines, the commencement of 
 the existing ordainings of our planet. It is true, that Dr 
 Dawson's discovery of worm-burrows in the upper Lauren- 
 tians, if further corroborated, would carry the inference 
 
 G 
 
98 THE PRIMARY PERIODS. 
 
 of Life-beginnings still lower than the lowermost Lau- 
 rentians, and into strata which, in the absence of fossil 
 remains, we are in the habit of designating " meta- 
 morphic ; " but then be it observed that the distance in 
 time between the upper and lower Laurentians is very vast, 
 and that the carrying of lowly life-forms even beyond the 
 Laurentian epoch does not materially affect the conclusion. 
 It is merely believed we are approaching, not asserted we 
 have reached the ultimate limit of vitality. 
 
 Of course everything connected with these investigations 
 is as yet dim and difficult. We know next to nothing of 
 the areas occupied by Laurentian and Cambrian strata, and 
 can only sketch in very general terms the boundaries of 
 the Silurian. We know nothing of the lands from which 
 the Laurentian and Cambrian sediments were borne, and 
 can only dimly indicate the direction from which some of 
 the Silurian were transported. The vast thickness of these 
 formations, the frequent alternations of their strata, and 
 the fineness of the sediments, imply long lapses of time 
 but how long it were in vain, without some standard of com- 
 parison, to inquire and even though we could give the time 
 numerical expression in years and centuries, we could form 
 no adequate conception of its immensity. All that we 
 know for certain is, that the earth in these primeval periods 
 had its seas and continents seas in which sediments were 
 deposited, and lands from which the material must have 
 been borne. With the exception of a few Silurian stems 
 and seed-vessels, we are in utter ignorance of the life and 
 aspects of these lands ; and are merely left to infer the exist- 
 ence of other forms of life from the presence of those we 
 have determined. Of the tenantry of the seas we know that 
 they were few and simple at first, but, as time rolled on, 
 newer and higher types made their appearance, and this 
 not only in greater numerical abundance, but in greater 
 
THEIR GEOGRAPHICAL ASPECTS. 99 
 
 specific variety. No doubt the record is very imperfect, 
 and we cannot for a moment suppose that all the forms of 
 life have been revealed by the few scattered patches geolo- 
 gists have examined. Still, there must be a meaning in 
 these lowliest forms of life coming first, in their compara- 
 tive scantiness in the earliest formations, in the gradual 
 appearance of higher and higher forms, and in their in- 
 creasing abundance and specific variety ; and that meaning, 
 if we would interpret without bias or predilection, is 
 surely this that in these old formations we are approach- 
 ing if indeed we have not already reached the dawning 
 of life and the first orderings of that system of progression 
 that still prevails, and is carrying the present along with it. 
 
 Such, once more, is the faint and fragmentary history of 
 the earth's primal periods dim and shadowy loomings of 
 undiscovered lands ; glimpses of broad seas in which the 
 lowlier forms of life spread and increased in numbers, and 
 rose by some great creative law through newer species to 
 higher and higher orders. Fragmentary as the history may 
 seem, it is truly marvellous that science, dealing with such 
 obscure materials, should have been able, within little more 
 than a quarter of a century, to arrive at such satisfactory 
 conclusions. Within the memory of living geologists these 
 Silurian, Cambrian, and Laurentian systems were the 
 " Transition," " Metamorphic," " Hypozoic" (under life), 
 and " Azoic" (void of life) rocks of the systematists ; and 
 now each and all of them have yielded their life-forms 
 proving the great fact, that there is no known period of the 
 earth's history when life, in some form or other, did not 
 exist, and leading to the belief that the manifestation of 
 life on our planet was coeval with the earliest of the strati- 
 fied formations. How wonderful the interest with which 
 these chips and fragments can invest the history of the 
 
100 THE PRIMARY PERIODS. 
 
 past ! Like the prehistoric relics of the shell-mounds, the 
 lake-dwellings, the caves, and the river-gravels, they may 
 lead to no very definite or connected view of the aspects 
 and history of the periods to which they relate; but to 
 science they are invaluable as proving what has been there, 
 and as indicating the design and method of creation. 
 Where everything is so obscure the faintest glimmer be- 
 comes an unspeakable boon a certainty of itself where- 
 from to predicate, and the strongest incentive to further 
 investigation. 
 
VEINS THEIE NATUKE AND OKIGIK 
 
 VEINS AND DYKES, HOW OCCASIONED METALLIFEROUS VEINS, MOST 
 ABUNDANT IN THE PRIMARY ROCKS REASON OF THIS ABUND- 
 ANCE GENERAL CHARACTERISTICS OF VEINS VARYING NATURE 
 OF THE MINERAL SUBSTANCES BY WHICH VEINS ARE MAINLY 
 FILLED MODE IN WHICH THESE VEIN-STUFFS ARE AGGREGATED 
 RELATIONS OF THE ORES TO THE VEIN-STUFFS DIRECTION OF 
 VEINS IN CERTAIN LOCALITIES RIGHT-RUNNING AND CROSS VEINS 
 THEORIES OF FORMATION AND FILLING INFILTRATION AND 
 DEPOSITION OF CHEMICAL SOLUTIONS EFFECTS OF THERMAL 
 AGENCY ELECTRIC AND OTHER KINDRED CURRENTS RELATIONS 
 TO CENTRES OF IGNEOUS ACTION IMPORTANCE OF METALLIFER- 
 OUS VEINS CONTRAST BETWEEN THE MINERAL AND AGRICUL- 
 TURAL VALUE OF PRIMARY DISTRICTS MINES AND STREAM- 
 WORKS MINING INDUSTRY, AND IMPORTANCE OF SOUND GEO- 
 LOGICAL DEDUCTION. 
 
 IT has been stated in the preceding Sketch, that of all the 
 rocks in the earth's crust, the primary are those most abun- 
 dantly traversed by veins. As these veins are the great 
 repositories of the metallic ores, it may be useful at this 
 stage briefly to explain what veins are, how they occur, and 
 what the general character of their contents. This informa- 
 tion may lead to a better comprehension of much that will 
 be subsequently stated, at the same time that it is valuable 
 knowledge of itself, and belongs to one of the most inter- 
 esting departments of modern geology. 
 
 It was mentioned under Vulcanicity, that in all volcanic 
 areas the solid crust was more or less rent and fissured 
 these rents either radiating from some centre of eruption, 
 
102 V "-VEINS THEIR NATURE AND ORIGIN. 
 
 -or- Tii&aing /parallel to each, other according to the most 
 prevalent direction of the earthquake convulsions. These 
 fractures will vary, of course, from mere cracks to yawning 
 chasms many feet in width, and will descend at all inclina- 
 tions some sloping downwards at a low angle, and others 
 sinking perpendicularly, or nearly so. Now it requires no 
 great effort of the understanding to perceive that these 
 fissures, in course of time, will be filled either by matter 
 washed in from the earth's surface, or by volcanic and 
 mineral substances injected from the interior. Such rents 
 in the stratified rocks, when thus filled up by lava, by 
 greenstone, or by basalt, are generally known as " dykes," 
 the igneous matter rising up like a wall through the strata 
 on either side. On the other hand, when they are filled 
 by sparry or crystalline minerals, and these intermingled 
 more or less with metallic ores the slow and gradual de- 
 positions of chemical agency they are usually distinguished 
 as " Veins," from their traversing and ramifying through 
 the crust like the veins through the animal system. But 
 the veins that were formed at one period may be cut 
 through or crossed by others of a later era, and thus in 
 many districts there is a network, as it were, of veins, 
 crossing and intercrossing in a very complicated manner. 
 As might be expected, too, the original veins may contain 
 one kind of mineral or metal, and the cross- veins another 
 kind, and hence the greater richness, as well as complexity, 
 of many metalliferous regions. 
 
 Understanding, then, that " dykes " consist of unproduc- 
 tive rock-matter, and that " veins " are always less or more 
 metalliferous, it may be stated as a fact, that the latter 
 occur most abundantly, and naturally so, in the primary 
 formations. These are the rocks that have suffered most 
 from igneous convulsions, and these also are the rocks 
 among which metamorphism and chemical agency have had 
 
THEIR CHARACTERISTICS. 103 
 
 longest time to bring about internal change and fill with 
 crystalline and metalliferous depositions. There are, no 
 doubt, productive veins in later formations, such as the 
 lead and silver bearing veins of the Carboniferous limestone ; 
 but these by no means occur in the same richness and 
 variety as those of the primary strata. Wherever, then, 
 we have extensive developments of primary rocks and 
 mountains, as in Wales and Cornwall, Scandinavia, the 
 Ourals, the Andes and Mexican Sierras, there also we may 
 expect a corresponding development of metalliferous veins 
 gold, silver, tin, copper, and the like of varying age 
 and richness, according to certain laws the order and gover- 
 nance of which geology is yet unable to indicate. The. for- 
 mation and accumulation of rocks is in most instances a 
 slow and gradual process, but the segregation and deposition 
 of metalliferous matter is still slower, and thus we may look 
 upon the veins of the primary strata as of high antiquity, 
 though necessarily younger than the rocks they traverse. 
 Occurring most abundantly in the older formations, and 
 very rarely in those of secondary or tertiary date, it is to 
 the veins and veinstones of primary regions that the follow- 
 ing remarks will be more especially directed. 
 
 Defining a vein as a rent or fissure in the earth's crust 
 which has been subsequently filled up by infiltrations of 
 mineral and metallic matter, it must be obvious that veins 
 will be of various widths and of various inclinations. Pro- 
 ductive veins seldom exceed a few feet in width, and it is 
 rare to find them beyond fifteen or twenty; but their in- 
 clinations are at all angles some descending almost per- 
 pendicularly, and others sloping downwards by very easy 
 stages. The bounding rocks on either side form the 
 cheeks or walls of a vein ; the mineral matter of which it 
 is composed, the vein-stuff, 'matrix, or gangue ; and the 
 metallic ore is distributed through the matrix in ribs, 
 
104 VEINS THEIR NATUEE AND ORIGIN. 
 
 pockets, nests, strings, and plates, according to the manner 
 and abundance of its occurrence. The vein-stuff is usually 
 arranged in layers from the walls inwards, the centre being 
 generally occupied by a rib of ore, though not unfre- 
 quently hollow and lined with crystals. The whole matrix 
 has thus a striped or veined appearance, the stripes run- 
 ning up and down or parallel to the cheeks or containing 
 walls. It must be obvious from this description that a 
 vein is something very distinct from the rocks through 
 which it passes. If it pass through igneous rocks, its 
 stripes and colours contrast very strongly with the dark 
 uniform hues of these masses; if through sedimentary 
 rocks, its upward and downward course through their strata 
 at once arrests the attention ; and, generally speaking, its 
 sparry or crystalline texture is sufficient to define its thick- 
 ness and direction. Passing from below upwards, and 
 frequently ramifying, crossing, and intercrossing in many 
 directions, they look indeed like the veins in vegetable and 
 animal structures, and hence their appropriate and expres- 
 sive designation. 
 
 The sparry matter which forms the bulk of the vein- 
 stone or matrix consists for the most part of quartz, car- 
 bonate and sulphate of lime, carbonate and sulphate of 
 baryta, or of alternations and admixtures of these the ore 
 occupying a subordinate part in ribs, strings, nests, and 
 pockets. These vein-stuffs seem to have been deposited first 
 on the cheeks, and then coating after coating towards the 
 centre, which is either solid like the rest of the matrix, or 
 hollow, as if there had been a deficiency of filling matter ; 
 and, in such cases, the cavity is lined with crystals shoot- 
 ing and pointing inwards. Having had room to assume 
 their independent forms, the crystals in these cavities are 
 often of great beauty, and it is usually from such vein- 
 spaces that the mineralogist obtains his rarest treasures. 
 
THEIR CONTENTS AND DIRECTIONS. 105 
 
 In some instances the vein-stuff consists of a single sub- 
 stance in repeated coatings, such as quartz or carbonate of 
 lime ; in other instances it is made up of alternating layers 
 of two substances, such as lime and baryta ; and in many 
 cases it consists of a seemingly capricious admixture of 
 several ingredients. As with the vein-stuffs so with the 
 enclosed metallic ores some veins containing only one 
 metal, others two or more metals, and in such cases there 
 is usually a curious and persistent connection, as lead with 
 silver, copper with tin, iron with manganese, and gold with 
 platinum. Besides this curious connection of metal with 
 metal, there is often an observed relation between certain 
 ores and certain vein-stuffs, as gold in quartz, lead in car- 
 bonates and fluates of lime, &c. ; and these relations when 
 carefully noted are often of great practical value to the 
 mineral explorer. What has caused these curious alterna- 
 tions of vein-stuffs and connections of certain metals science 
 cannot in the mean time determine, but it observes the 
 modes in which they occur, and this, when accurately done, 
 is always a step towards the solution. Whatever the causes, 
 they have operated not always in filling the veins and fis- 
 sures merely, but often in impregnating the adjacent rocks 
 through which the veins pass, and thus the cheeks or walls 
 are occasionally worked for the strings and plates of the 
 ores they contain. 
 
 But though unable to explain the relations of certain 
 ores to certain vein-stuffs, geology has amassed a great 
 deal of observation on the subject, as well as on the preva- 
 lent direction or strike which veins take in certain locali- 
 ties. The ascertaining of this direction is all-important; 
 for while the main veins of a district containing one kind 
 of metal are found to strike always in one direction 
 easterly and westerly, for instance the secondary or cross 
 veins running northerly and southerly are almost certain to 
 
106 VEINS THEIR NATURE AND ORIGIN. 
 
 "be the repositories of other kinds of ore. As the main 
 veins or "lodes" are thus intersected by others of more 
 recent date, they will also be more or less displaced, and 
 the ascertaining of these facts is ever of the highest 
 moment to the mining industry of a district, to say nothing 
 of its importance to correct geological deduction. The 
 mapping of these directions and the colouring of the 
 primary and secondary veins according to the kind of ores 
 they contain, is a work to be done by the mining-engineer 
 for each respective district ; though it is now well known, 
 that according to the rocks of a country and the age and 
 direction of its hills, so also are the general strikes of the 
 veins and the nature of their metalliferous contents. The 
 direction of veins and the nature of their contents reveal a 
 chronology and order within their respective areas as much 
 as the stratified systems do, and a knowledge of these rela- 
 tions is alike of scientific and economic importance. 
 
 At the present time attention has been less directed to 
 the direction of veins and the corresponding nature of their 
 contents than to the modes of their formation and their 
 subsequent infiltrations. At one time igneous action was 
 called in by hypothesists, not only to produce the original 
 fissures, but to accomplish also the subsequent fillings-in ; 
 and, in fact, to perform the most opposite and contradictory 
 functions. Now, however, while it is agreed that the rents 
 and fissures were originally produced by, and owe their 
 linear directions to, vulcanic commotions, it is the general 
 and growing opinion that their subsequent fillings-in with 
 sparry and metallic matters are due to the infiltration and 
 deposition of chemical solutions. Heated waters and va- 
 pours, or hydro-thermal action, as it has been termed, has 
 been the main agent in dissolving, carrying upwards, and 
 re-depositing the mineral and metallic matters that is, the 
 sparry vein-stuffs as well as the crystallised ores. In fact, 
 
MOST ABUNDANT IN IGNEOUS DISTRICTS. 107 
 
 similar spars and ores can be produced in the laboratory by 
 chemical and electrical means, and all the more certainly 
 that heat is present to facilitate the operation. What can 
 be simulated on the small scale by art we may readily be- 
 lieve to be producible by nature on the large, and thus to 
 chemical and electro - chemical agency are now generally 
 attributed the formation of vein-stuffs and their associated 
 ores. We have spoken of the greater efficiency of heated 
 waters in dissolving and holding in solution mineral and 
 metallic matters, but the effects of water in general (whether 
 hot or cold) must not be overlooked, it being the grand 
 medium through which the contents of veins have been 
 conveyed to their present positions. It is this belief .in 
 chemical solution and re-deposition which distinguishes 
 the modern theories of mineral veins from the older views 
 of sublimation through igneous or plutonic action. 
 
 Whatever may have been the immediate agent of infil- 
 tration and deposition, one thing is certain, that veins, 
 and especially metalliferous ones, are most abundant in 
 areas that have been long subjected to igneous action. 
 There is the closest connection, and necessarily so, between 
 the two phenomena, as it is only in convulsed districts that 
 rents and fissures can occur, and in such districts also that 
 such fissures have the greatest chance of being most rapidly 
 filled with mineral and metallic precipitates. Wherever, 
 therefore, there are old hill-ranges and primary areas that 
 have been repeatedly subjected to subterranean forces, there 
 we may expect veins and cross-veins each set representing 
 a long course of time, and being for the most part filled 
 with its own special ores and vein-stuffs. All portions of 
 a hill-range may not be rich alike, for there are certain 
 centres in which the producing forces seem to have acted 
 with greater intensity, or at all events to have been longest 
 
108 VEINS THEIR NATURE AND ORIGIN. 
 
 continued, and it is in these that the greatest variety of veins 
 and cross-veins occur, and from these also that the greatest 
 variety of metallic ores are to be obtained. What the law 
 that has determined the greater richness of certain districts, 
 science cannot as yet give the slightest indication, any more 
 than it can tell why certain areas that were once convulsed 
 with igneous activity have long since been cold and silent. 
 All that can be done in the mean time is simply to note the 
 facts, and these, when correctly recorded, become of the 
 greatest importance to industrial operations, as they will 
 one day or other do to scientific deduction. 
 
 The importance of correct information on all that re- 
 lates to metalliferous veins and deposits cannot be too 
 highly valued, and especially in countries like Britain, that 
 depend so much upon the metals for their mechanical, 
 manufacturing, and commercial greatness. Whether as a 
 medium of exchange, for the fabrication of implements 
 and the construction of machines, or merely for objects of 
 luxury and ornament, the metals are all-important ; and 
 whatever tends to certainty and facility in obtaining their 
 ores is deserving of a nation's encouragement. Without the 
 metals there cannot, indeed, be high and substantial pro- 
 gress in civilisation ; and in modern times a nation's place 
 may be safely indicated by the facilities she has of obtain- 
 ing them. Her hills may be bleak and barren, and little 
 fitted for the amenities of agriculture ; yet beneath that poor 
 and rugged surface may lie mines of untold wealth, and 
 the readiest means of manufacturing and commercial great- 
 ness. And such is usually the contrast that presents itself 
 in mining and metalliferous districts. Cold and retentive 
 clays, ungenial moorlands and uplands, are too often charac- 
 teristic of coal tracts, as witness those of Northumberland, 
 Durham, and Lanarkshire; while cliffs, and scars, and 
 bleak unapproachable ridges, are the common concomitants 
 
MINES AND STREAM-WORKS. 109 
 
 of metalliferous regions, as those of Derbyshire, Wales, and 
 Cornwall. 
 
 The great value of primary districts lies, as already men- 
 tioned, in their metalliferous lodes and veins, or in the 
 stream-drifts that have been weathered and worn in course 
 of ages from the cliffs and precipices above. The vein lies 
 in the solid rock, and must be mined with great labour and 
 outlay; the stream-drift, on the other hand, is but the 
 water-borne debris from the veins above, and demands 
 merely sorting and washing. The stream-work is the ready 
 and primitive method of obtaining the ores and metals ; 
 the mine is the laborious but more certain appliance of 
 modern times and modern requirements. In conducting a 
 stream-work, little more is needed than manual labour and 
 care in managing a mine, mechanical appliances, engineer- 
 ing skill, and correct geological deduction are indispensable 
 at every stage of the undertaking. 
 
 Such is a brief, and necessarily sketchy, outline of the 
 nature and origin of veins and vein-stuffs. The rents or 
 fissures originally produced by subterranean convulsion are 
 subsequently filled by infiltrations of mineral and metallic 
 matter, and thence become the veins which seem to ramify 
 and reticulate through the earth's crust like the veins 
 through vegetable and animal structures. A fissure may be 
 produced in an instant by earthquake convulsion, but ages 
 may pass before it be completely filled by sparry minerals 
 and metallic ores the slow depositions from aqueous per- 
 colation and solution. As water is ever percolating the 
 earth's crust, so it is ever dissolving from one part and re- 
 depositing in another ; and this power of dissolving is no 
 doubt greatly augmented by heat, just as rapidity of pre- 
 cipitation and crystallisation may be facilitated by electro- 
 magnetic currents which are incessantly traversing the 
 
110 VEINS THEIR NATURE AND ORIGIN. 
 
 rocky framework. In this way the fissure becomes a vein ; 
 and as each set of veins has a fixed direction, and is 
 charged with its own peculiar vein-stuff and metal, the 
 ascertaining of these directions and peculiarities is at once 
 of the highest scientific and economic importance. As the 
 original fissures are produced by volcanic convulsions, and 
 the subsequent fillings-in by slow and gradual precipitation 
 from solution, veins will occur most abundantly, of course, 
 in districts that have been longest subjected to those 
 agents ; and such tracts are necessarily those occupied by 
 primary and transition strata. In these districts, bleak 
 and barren and inhospitable, the mining industry of the 
 world is chiefly situated, their subterranean wealth compen- 
 sating, and often more than compensating, for their want 
 of agricultural fertility and amenity. As the metals are in- 
 dispensable to mechanical, manufacturing, and commercial 
 progress, so they are generally regarded as powerful auxili- 
 aries of civilisation ; hence the importance of all that at- 
 taches, scientifically and industrially, to their history, their 
 modes of occurrence, the means of obtaining them, and the 
 processes of reducing them from their ores and associated 
 vein-stuffs. 
 
FOSSILS THEIR NATURE AND ARRANGE- 
 MENT. 
 
 THE TERMS FOSSIL AND STJB-FOSSIL SCIENCE OF PALEONTOLOGY 
 FOSSILS, HOW IMBEDDED AND PRESERVED THEIR IMPORTANCE 
 IN GEOLOGY INDICATORS OF GEOGRAPHICAL CONDITIONS IN 
 THE PAST OF NATURE AND KIND OF LIFE DURING SUCCESSIVE, 
 PERIODS OF WORLD-HISTORY DIFFICULTIES ATTENDING PALE- 
 ONTOLOGICAL RESEARCH ORGANISMS MOST PERFECTLY PRE- 
 SERVED PROCESSES OF PETRIFACTION CONDITIONS IN WHICH 
 
 FOSSILS USUALLY OCCUR REQUISITE SKILL FOR THEIR INTER- 
 PRETATION BOTANICAL AND ZOOLOGICAL ARRANGEMENT OF 
 THIS PRELIMINARY KNOWLEDGE NECESSARY TO THE STUDY OF 
 GENERAL GEOLOGY. 
 
 WHATEVER may have been the meaning which our fore- 
 fathers attached to the term fossil (Lat. fossttis, dug up), 
 every man and woman of ordinary intelligence now under- 
 stands that it refers to the remains of plants and animals 
 found in the crust of the earth, and more or less petrified 
 or converted into stony matter. "Where these remains 
 whether trunks, branches, or leaves, bones, teeth, or shells 
 occur in recent and superficial accumulations, they appear 
 little altered in texture, and are usually looked upon as 
 sub-fossil, or only partially fossil ; but when they are im- 
 bedded in the older and harder strata, the stony conversion 
 is in general complete, and they are then regarded as true 
 fossils or petrifactions. Wherever they are found their 
 history excites a lively interest ; and minds altogether un- 
 attracted by the physical record of the earth are often 
 
112 FOSSILS THEIR NATURE AND ARRANGEMENT. 
 
 excited to enthusiasm in the search of its organic memorials. 
 Their study is, in fact, a kind of archaeology an antiqua- 
 rianism like that which attaches to ruins and burial- 
 mounds, but of a broader and more marvellous description. 
 To the older geologists their occurrence was a riddle, and 
 few considered them as other than mere accidents or lusus 
 natures ; but to the modern geologist they are replete with 
 information of the world's past, revealing to him the kind 
 of life that peopled its lands and waters during the succes- 
 sive stages of its history, and, by inference, the geographical 
 conditions under which they nourished and declined. The 
 recognition of their nature and importance has thrown a 
 new and higher interest round geology; and where the 
 study of mere rocks and minerals formerly shed an uncer- 
 tain glimmer, the science of fossils has cast the light of 
 sure and satisfactory information. This science of fossils, 
 or Palceontology, as it is technically termed (Gr. palaios, 
 ancient; onta, beings; and logos, discourse or reasoning), is 
 now, indeed, one of the main sections of geology; for if 
 geology be world-history, that history can never be written 
 without a knowledge of the plants and animals that have 
 successively peopled the earth, as well as of the external 
 conditions which the nature of these plants and animals 
 alone can indicate. It is necessary, then, that the student 
 of popular geology should know what fossils really are, the 
 various states in which they occur, and the manner in 
 which they can be arranged according to the classifications 
 of the botanist and geologist. To these subjects we devote 
 the present Sketch, premising that Palaeontology may be 
 technically subdivided into Palceophytology, or the science 
 of fossil plants, and Palceozoology, or the science of fossil 
 animals ; though, for all ordinary purposes, the general 
 term is sufficiently comprehensive and intelligible. 
 
 Like other things in the history of the earth, the nature 
 
HOW IMBEDDED. 113 
 
 and occurrence of fossils will be best explained by an 
 appeal to the existing operations of nature. If we stand by 
 the side of a river, and especially when it is in flood, we 
 perceive that the current is continually bearing onward 
 vegetable and animal debris, and that this debris is gradually 
 entombed among the mud, sand, and gravel which the river 
 deposits in the lake, estuary, or sea into which it discharges 
 its waters. As with one river, so with every rill and river 
 that traverses the terrestrial surface each is carrying 
 down the spoils of the land in a state more or less frag- 
 mentary, and burying them in the silt, where, excluded 
 from atmospheric decay, they appear in the first stages of 
 fossilisation. As with land plants and animals, so with 
 those of lakes and seas j they die and are imbedded in sedi- 
 ments where they lived and grew, or are drifted by tides 
 and currents to some distant locality. This process is ever 
 going forward in every region tropical, temperate, and 
 arctic; and as each region is characterised by its own 
 special flora and fauna, the imbedded remains will indicate 
 to future observers the external conditions under which they 
 grew and were deposited. The plants and animals entombed 
 in the estuary of the Amazon must differ from those de- 
 posited in the delta of the Mississippi, and these again from 
 those preserved in the mud-islands of the Niger, the Ganges, 
 and other Old World rivers. The shells, Crustacea, and 
 fishes that die and sink in the sediments of tropical seas 
 differ widely from those of temperate waters, and these 
 again as widely from the fauna of the Arctic and Ant- 
 arctic Oceans. As it is now, so it must have been in all 
 former ages, and thus the fossils of the stratified formations 
 become the only clue to the geographical conditions of the 
 areas in which they were deposited, and of the regions from 
 which they were derived. 
 
 Nor is it geographical or climatic condition alone of which 
 
 H 
 
114 FOSSILS THEIR NATURE AND ARRANGEMENT. 
 
 these fossil relics bear evidence. Every family of plants 
 has its own peculiar station the waters, the marsh, the 
 plain, the upland, or the shingly desert ; and every family 
 of animals its own special habitat the forest, the open 
 plain, the shallow lake, the sandy or muddy shore, or the 
 greater ocean-depths. As these families are regulated now, 
 so the palaeontologist presumes they were governed in former 
 epochs, and thus by a critical study of his fossils he arrives 
 at a more vivid picture of the past, and can associate with 
 each order and family the general features of their physical 
 surroundings. From his knowledge of the present he rises 
 to a true conception of the past, and from his acquaintance 
 with the existing he can indicate with something like 
 certainty the habitats and distribution of the extinct. It 
 is true there will be occasional comminglings of terrestrial 
 and aquatic remains, of fresh-water and marine, just as now 
 the spoils of the land may be mingled with those of the 
 estuary, and those of the river with those of the ocean; 
 but in general such commixtures are limited, and do not 
 obliterate the broader characteristics of the formations in 
 which they occur. Here and there the record may be com- 
 plicated ; it is never equivocal or disguised. 
 
 ]S r or is it mere habitat and distribution the palaeontologist 
 can thus arrive at ; but habit and function are also deter- 
 minable by the requisite anatomical skill. The forelimb to 
 swim, the forelimb to walk, the forelimb to run, the fore- 
 limb to seize, and the forelimb to fly, are each stamped by 
 its own essential characteristics, just as the herbivorous, the 
 carnivorous, and the insectivorous teeth are ; and thus the 
 competent palaeontologist is enabled to recall not only the 
 physical surroundings of his fossil flora and fauna, but their 
 forms and functions presenting a picture of the world's 
 past like that which the geographer presents of its existing 
 phenomena. There are few things, indeed, which science 
 
HOW DECIPHERED. 115 
 
 has greater cause to boast of than this determination and 
 restoration of fossil forms. From a few stray chips and 
 fragments to reveal the nature of the plant or animal to 
 which these fragments belong, or from, a few scattered bones 
 and teeth to reconstruct the form of the creature and in- 
 dicate its habits and functions, is, in truth, the triumph of 
 modern anatomy. " Every organised being" says the im- 
 mortal Cuvier, "forms a whole, a single circumscribed 
 system, the parts of which mutually correspond and concur 
 to the same definite, action by a reciprocal reaction. None 
 of these parts can change without the others also changing, 
 and consequently each part, taken separately, indicates and 
 gives all the others" In this truth lies the fundamental 
 law of the co-relation of parts, the discovery of which en- 
 abled the great French anatomist to effect his wonderful re- 
 storations of the mammals of the Paris Basin, and the enun- 
 ciation of which has ever since thrown the light of hope 
 and of certainty over the toilsome labours of the palaeonto- 
 logist. To him fossils became, as they have been eloquently 
 and appropriately termed, the MEDALS OF CREATION ; " for 
 as an accomplished numismatist, even when the inscription 
 of an ancient and unknown coin is illegible, can from the 
 half- obliterated effigy, and from the style of art, determine 
 with precision the people by whom and the period when it 
 was struck ; so in like manner the geologist can decipher 
 these natural memorials, interpret the hieroglyphics with 
 which they are inscribed, and, from apparently the most 
 insignificant relics, trace the history of beings of whom no 
 other records are extant, and ascertain the forms and habits 
 of unknown types of organisation, whose races were swept 
 from the face of the earth thousands of ages before the 
 creation of man and the creatures which are his contem- 
 poraries."* 
 
 * MantelTs ' Medals of Creation,' vol. i. p. 17. 
 
 
116 FOSSILS THEIR NATURE AND ARRANGEMENT. 
 
 Of course, all plants and animals are not preservable 
 alike, nor are the same organisms, though occurring in the 
 same formation, always found in the same state of preser- 
 vation. Plants and animals that have been exposed to 
 atmospheric decay before entombment will be less perfect 
 than those that have been suddenly and thoroughly im- 
 bedded. The harder parts of plants roots, stems, leathery- 
 leaves, and nut -like fruits will run a better chance of 
 preservation than the soft and succulent portions. Corals, 
 shells, crusts, bones, teeth, scutes, and scales, will be pre- 
 served when all the softer parts of the animals to which 
 they belong have entirely disappeared. The harder and 
 more massive portions of a skeleton will resist when the 
 softer and more slender have fallen to decay. The dense 
 and thoroughly ossified bones of an old animal will endure 
 where the spongy and unanchylosed members of a young 
 one fall asunder and perish. Ferns, mosses, and resinous 
 pines will resist maceration when other plants will totally 
 disappear. All things considered, aquatic animals run a 
 better chance of pre^ejcxatiQILthan terrestrial ones ; an3. the 
 bulkier land-mammals and amphibialfchan the birds and 
 insects. Gregarious animals, too, are likely to be found 
 in greater abundance than those living isolated and soli- 
 tary the catastrophe (earthquake, land-flood, or wind- 
 storm) which would destroy only a few of the latter, over- 
 whelming the former by hundreds of thousands. In this 
 way shoals of fishes may be suddenly suffocated by sub- 
 marine exhalations, shell-beds buried beneath obnoxious 
 sediments, herds of ruminants borne from the land by floods, 
 and clouds of insects swept into the sea by wind-storms. 
 The inconceivable numbers in which fossils are sometimes 
 found crowded into very limited areas would seem to point 
 to such accidents for their entombment their perfection, 
 
HOW PRESERVED. 117 
 
 indiscriminate aggregation, and individual positions, all in- 
 dicating some sudden death-catastrophe. 
 
 The nature of the sediments must also exercise a marked 
 influence in the number and perfection of the imbedded 
 fossils. Loose and porous sands will be less preservative 
 than impervious clays and muds, and heterogeneous silts 
 than calcareous sediments. In this way minute organisms 
 may totally disappear, and larger ones be preserved in a 
 mutilated and fragmentary form. Every one acquainted 
 with the nature of our peat-mosses, with the sands, clays, 
 and marls that fill up our ancient lakes, and with the sands, 
 gravels, and silts now accumulating in our estuaries and sea- 
 creeks, must have witnessed the different preservative effects 
 of these sediments ; how solid and dense the bones are in 
 one, and how spongy and rotten they appear in another ; 
 how hard and firm the shells are in one, and how soft and 
 friable they occur in another ; and how sharp and clear 
 every external marking is retained in one matrix, and how 
 wasted and obscure it becomes in another. As with these 
 recent accumulations, so with the strata of the older forma- 
 tions; some are destitute of organic remains, which must 
 at one time have been imbedded in them in abundance, 
 while in others they are so imperfectly preserved as to be 
 of little or no value to the palaeontologist. The various 
 ways in which plants and animals may be imbedded and 
 preserved in sediments being so obvious, the different pre- 
 servative effects of different sediments being also apparent, 
 the reason why some forms should occur more abundantly 
 than others being generally discoverable, and the evidences 
 which such plants and animals afford of the geographical 
 conditions under which they flourished being admitted, let 
 us now inquire into the processes by which they are lapidi- 
 fied, or converted into stony matter. 
 
118 FOSSILS THEIR NATURE AND ARRANGEMENT. 
 
 Generally speaking, in recent accumulations, such as sand- 
 silt, peat-moss, and the like, the remains of plants and 
 animals are found little altered. The more volatile matters 
 are expelled from the plant, and the more perishable in- 
 teguments and softer tissues of the animal have perished. 
 Boots, trunks, "branches, and the harder fruits, if excluded 
 from the action of the atmosphere, become darker, denser, 
 and assume a peaty aspect. In like manner, bones, horns, 
 teeth, shells, and crusts, lose a portion of their animal 
 matter, and become denser and heavier through some slight 
 absorption of mineral ingredients. But in all the older 
 formations the vegetable, if not converted into coal, is 
 thoroughly lapidified that is, changed by a slow chemical 
 process into flint, ironstone, limestone, or sandstone, as the 
 case may be and merely retains its organic form ; while 
 animal remains undergo a similar conversion, and are 
 recognisable only through their individual forms and 
 textures, which continue unchanged and persistent. There 
 is nothing more marvellous than this process of petri- 
 faction : particle after particle as the organic matter dis- 
 appears, so particle after particle the mineral matter takes 
 its place, and this so delicately that scarcely a cell or 
 fibre is ever ruptured or displaced ! Of course where the 
 mineral solutions percolating the earth are so numerous 
 there will be great variety of petrifactions, some being 
 calcareous or limy, some siliceous or flinty, some ferruginous 
 or irony, and others bituminous or coaly. But in whatever 
 state they may occur the process seems the same namely, 
 a gradual dissipation, through decay, of the organic atoms, 
 and a gradual substitution, through permeation, of the 
 mineral or inorganic. Great differences will also arise from 
 the chemical nature of the organisms themselves wood, 
 bone, horn, teeth, shells, crusts, and corals, each having its 
 
PROCESSES OF PETRIFACTION. 119 
 
 own composition, and possessing its own power of resisting 
 decay. Not only so, but as the percolation of mineral 
 solutions through the earth's crust is incessant, what is 
 deposited at one time may be dissolved at another and a 
 new substance substituted in its place, or no new substance 
 may be substituted, and merely the hollow mould of the 
 organism left to prove that it once was there. For instance, 
 a shell or coral, which consists of animal-formed carbonate 
 of lime, may be converted into sparry mineral carbonate ; 
 or this may be dissolved and carried away, leaving merely 
 a hollow mould with every ridge and line and pore im- 
 pressed on the containing matrix; or this mould may be 
 refilled with siliceous matter, and the shell or coral then 
 present itself as a flint, with every pore and ridge and wrinkle 
 as delicately perfect as on the original organism the day it 
 was imbedded. This perfection of preservation is often, 
 indeed, truly marvellous. We have seen the faceted eyes 
 of trilobites as perfect in form as when they received the 
 rays of light through Silurian waters ; carboniferous uni- 
 valves with their colour-bands still unobliterated ; internal 
 casts of products with their muscular apparatus displayed in 
 a style of legibility to which no anatomical preparation could 
 approach ; and ink-bags of cuttle-fishes so little changed as 
 to furnish the pigments for their own portraiture. 
 
 Of course, the consideration of these percolations, dissolu- 
 tions and substitutions, involves many intricate questions in 
 chemistry; but enough has been stated to inform the gene- 
 ral reader that fossils may occur in many different conditions 
 as stony conversions, as moulds, as casts, or as mere im- 
 pressions on the matrix in which they are entombed. But 
 in whatever state they may occur, there is usually sufficient 
 left either in general form, in external character, or in inter- 
 nal texture, to enable the palaeontologist to determine their 
 
120 FOSSILS THEIR NATURE AND ARRANGEMENT. 
 
 places, or at all events to approximate to their places, in the 
 vegetable and animal schemes. These determinations, in- 
 deed, constitute the main duty of palaeontology ; and when 
 one considers how widely scattered fossils usually are, how 
 sorely mutilated and fragmentary they often appear, and 
 that they are largely the chance findings of quarrymen and 
 miners, it is truly marvellous how much of reliable world- 
 history the science, within little more than half a century, 
 has been able to reveal. It is true there is still very much 
 to be done, and perhaps more in fossil botany than in fossil 
 zoology, inasmuch as vegetable organisms are less perfectly 
 preserved than animal, and because the classifications of the 
 botanist are mainly founded on the flowers and leaves 
 portions which of all others are the most evanescent and 
 perishable. Notwithstanding these difficulties, the palaeon- 
 tologist finds that all his fossils belong to the same great 
 scheme of life with existing plants and animals, and he is 
 therefore restricted to the classifications that have been de- 
 vised by the botanist and zoologist. Species, and genera, 
 and families, and even what are called orders, may have 
 become extinct, and others in the course of creation may 
 have taken their places; still the great Scheme of Vitality 
 has ever been evolved according to a fixed and determinate 
 plan, and in harmony with this plan, and to the best of 
 their knowledge, botanist, zoologist, and palaeontologist must 
 endeavour to conform their systematic arrangements. 
 
 In speaking of fossil plants, therefore, the palseophytologist 
 adopts the usual classification of the botanist, placing where 
 he can his fossils under their proper genera and orders, and 
 where he cannot, assigning to them a provisional place next 
 to the genus or order to which they bear the greatest resem- 
 blance. In this course he uses the same botanical terms, 
 and employs the same botanical phraseology, and these may 
 
UK I 
 
 r^v 
 
 PLANT REMAINS/^^gj^rpr 121 
 
 be rendered intelligible in a general way by the study of 
 the annexed tabulations : 
 
 The Vegetable Kingdom may be arranged into two grand divisions 
 the CELLULAR and VASCULAR ; and these again, according to their modes 
 of growth and reproduction, into the following groups and classes : 
 
 I. CELLULAR Without regular vessels, but composed of fibres which 
 
 sometimes cross and interlace each other. The Conferva (green scum- 
 like aquatic growths), the Lichens (which incrust stones and decaying 
 trees), the Fungi (or mushroom tribe), and the Algce (or sea- weeds), 
 belong to this division. In some of these families there are no ap- 
 parent seed-organs. From their mode of growth viz., sprout-like 
 increase of the same organ they are known as -THALLOGENS or 
 AMPHIGENS, and constitute the lowest orders of vegetation. 
 
 II. VASCULAR With vessels which form organs of nutrition and repro- 
 duction. According to the arrangement of these organs, vascular 
 plants have been grouped into two great divisions CRYPTOGAMIC 
 (no visible seed-organs), and PHANEROGAMIC (apparent flowers or 
 seed-organs). These have been further subdivided into the following 
 classes ascending from the lower to the higher forms : 
 
 1. CRYPTOGAMS Without flowers, and with no visible seed-organs. 
 
 To this class belong the mosses, equisetums, ferns, and lycopo- 
 diums. It embraces many fossil forms allied to these families. 
 From their mode of growth viz., increase at the top or grow- 
 ing point they are known as ACROGENS. 
 
 2. PHANEROGAMIC MONOCOTYLEDONS Flowering plants with one 
 
 cotyledon or seed-lobe. This class comprises the water-lilies, 
 lilies, aloes, rushes, grasses, canes, and palms. In allusion to 
 their growth by increase within, they are termed ENDOGENS. 
 
 3. PHANEROGAMIC GYMNOSPERMS This class, as the name indi- 
 
 cates, is furnished with flowers, but has naked seeds. It em- 
 braces the cycadece or cycas and zamia tribe, and the conifera 
 or firs and pines. In allusion to their naked seeds, these plants 
 are also known GYMNOGENS. 
 
 4. PHANEROGAMIC DICOTYLEDONS Flowering plants with two 
 
 cotyledons or seed-lobes. This class embraces all forest trees 
 and shrubs the composite, leguminosce, umbelliferce, cruciferce, 
 and other similar orders. None of the other families of plants 
 have the true woody structure, except the coniferce or firs, 
 which seem to hold an intermediate place between mono- 
 cotyledons and dicotyledons ; but the wood of these is readily 
 distinguished from true dicotyledonous wood. From their 
 mode of growth increase by external rings or layers they 
 are termed EXOGENS. 
 
122 
 
 FOSSILS THEIR NATURE AND ARRANGEMENT. 
 
PLANT REMAINS. 123 
 
 Subdividing still further, according to their most marked 
 characteristics, whether external or internal, the botanist 
 arranges all the known forms of Vegetable Life into some 
 300 orders, upwards of 9000 genera, and about 120,000 
 species. As the most of these distinctions, however, are 
 founded on the form and connection of the flower, fruit, 
 and leaf organs which rarely or never occur in connection 
 in a fossil state the palaeontologist is guided in the main 
 by the great structural distinctions above adverted to, and 
 not unfrequently by the simple but unsatisfactory test of 
 "general resemblance." The flower and the organ of 
 fructification may have perished, but still the form and 
 venation of the leaf, the external sculpturing of the bark, 
 the disposition of the leaves and branches, and the general 
 mode of growth, may be preserved; and from these, as 
 well as from a microscopic examination of the lapidified 
 tissues, the palseophytologist can for the most part deter- 
 mine, or at all events approximate to the determination of, 
 his fossil twigs and fragments. So certain, indeed, are the 
 determinations of the microscope, that where good sec- 
 tions can be procured, the competent observer rarely or 
 never fails to establish the great order to which the or- 
 ganism belongs ; and this, considering the difficulties 
 surrounding pala30phytology, is a triumph of no mean 
 description. 
 
 As the palaeophytologist, in arranging his fossil organ- 
 isms, is guided by the classification of the botanist, so the 
 palaeozoologist follows, as closely as the nature of his ob- 
 jects will permit, the systematic schemes of the zoologist. 
 And in this he has altogether an easier task, inasmuch as 
 animal organisms, from their less destructible nature, are 
 in general more perfectly and legibly preserved. The 
 horny and calcareous structures of zoophytes, corals, shells, 
 crusts of Crustacea, calcareous tubes of annelids, chitonous 
 
124 FOSSILS THEIR NATURE AND ARRANGEMENT. 
 
 wing-sheaths of insects, and the like, are well-known in- 
 stances of this comparative indestructibility among the 
 invertebrata ; while bony scales and scutes, horns, bones, 
 and teeth are still more familiar examples, perhaps, among 
 the vertebrata. In this way, partly by external form, 
 partly by internal structure, and partly by the great anato- 
 mical law of the co-relation of parts, the palseozoologist is 
 enabled to arrive at determinations more satisfactory, on 
 the whole, than those of the palseophytologist. Species, 
 genera, families, and even whole orders, may be extinct ; 
 but, comparing his organisms with the existing, he finds 
 their nearest affinities, and assigns them their place in the 
 systematic arrangements of the zoologist. For this pur- 
 pose the subjoined scheme is in general sufficient, and its 
 study in this place wall greatly facilitate the reader's com- 
 prehension of w r hat may be subsequently stated respecting 
 the fossils of the different formations : 
 
 SCHEME OF ANIMAL CLASSIFICATION. 
 
 VERTEBRATA, 
 
 Or animals with backbone and bony skeleton, and comprehending 
 
 MAMMALIA, AVES, REPTILIA, and PISCES. 
 I. MAMMALIA, or Sticklers; subdivided into Placental and Aplacental. 
 
 1. PLACENTAL, bringing forth mature young. 
 BIMANA (Two-handed) Man. 
 
 QUADRUMANA (Four-handed) Monkeys, Apes, Lemurs. 
 CHEIROPTERA (Hand-winged) Bats, Vampire-bats, Fox-bats. 
 INSECTIVORA (Insect-eaters) Mole, Shrew, Hedgehog, Banxring. 
 CARNTVORA (Flesh-eaters) Dog, Wolf, Tiger, Lion, Badger, Bear. 
 PINNIPEDIA (Fin-footed) Seals, Walrus. 
 RODENTIA (Gnawers) Hare, Beaver, Rat, Squirrel, Porcupine. 
 EDENTATA (Toothless) Ant-eater, Armadillo, Pangolin, Sloth. 
 RUMINANTIA Cud-chewers) Camel, Llama, Deer, Goat, Sheep, Ox. 
 SOLIDUNGULA (Solid-hoofs) Horse, Ass, Zebra, Quagga. 
 PACHTDERMATA (Thick-skins) Elephant, Hippopotamus, Rhinoceros. 
 CETACEA ( Whales) Whale, Porpoise, Dolphin, Lamantin. 
 
ANIMAL REMAINS. 125 
 
 2. APLACENTAL, bringing forth immature young. 
 MARSUPIALIA (Pouched) Kangaroo, Opossum, Poitched Wolf. 
 MOXOTREMATA (One-vented) Ornithorhynchus, Porcupine-ant-eaters. 
 
 II. AVES, or BIRDS. 
 
 RAPTORES (Seizers) ESgles, Falcons, Hawks, Owls, Vultures. 
 INSESSORES (Perchers) Jays, Crows, Finches, Sparrows, Thrushes. 
 SCASSORVS (Climbers) Woodpeckers, Parrots, Parroqueets, Cockatoos. 
 COLUMB^J (Pigeons) Common Dove, Turtle Dove, Ground Dove. 
 RASORES (Sa-apers) Barnfowl, Partridge, Grouse, Pheasant. 
 CURSORES (Runners) Ostrich, Emu, Apteryx. 
 GRALLATORES ( Waders) Rails, Storks, Cranes, Herons. 
 XATATORES (Surimmers) Divers, Gulls, Ducks, Pelicans. 
 
 III. REPTILIA, subdivided into Reptiles Proper and Batrachians. 
 1. REPTILES PROPER. 
 
 CHELONIA ( Tortoises) Turtles, Tortoises. 
 
 LORICATA (Covered with Scutes) Crocodile, Gavial, Alligator. 
 
 SAURIA (Lizards) Lizard, Iguana, Chameleon. 
 
 OPHIDIA (Serpents) Vipers, Snakes, Boas, Pythons. 
 
 2. BATRACHIANS, or FROGS. 
 ASOURA (Tail-less) Toad, Frog, Tree-Frog. 
 URODELA (Tailed) Siron, Triton, Salamander. 
 APODA (Footless) Lepidosiren, Blindworm. 
 
 IV. PISCES, or FISHES. 
 
 SELACHIA (Cartilaginous) Chimsera, Sharks, Sawfish, Rays. 
 GANOIDEA (Enamel-scales) Amia, Bony-pike, Sturgeon. 
 TELEOSTIA (Perfect-bones) Eels, Salmon, Herring, Cod, Pike. 
 CYCLOSTOMATA (CiYcte-rao^fo) Lamprey. 
 LEPTOCARDIA (Slender-hearts) Amphioxus. 
 
 INVERTEBKATA, 
 
 Or animals void of backbone and bony skeleton, and comprehending 
 
 ARTICULATA, MOLLUSCA, RADIATA, and PROTOZOA. 
 
 I. ARTICULATA, subdivided into Articulates and Vermes. 
 
 1. ARTICULATA, or Jointed Animals Proper. 
 INSECTA (Insects) Beetles, Butterflies, Flies, Bees. 
 MYRIAPODA (Many-feet) Scolopendra, Centipedes. 
 
126 FOSSILS THEIR NATURE AND ARRANGEMENT. 
 
 ARACHNIDA (Spiders) Spiders, Scorpions, Mites. 
 CRUSTACEA (Crust-dad) Crayfish, Crabs, Shrimps, Woodlice. 
 CIRRHOPODA (Curl-feet) Acorn-shells, Barnacles. 
 
 2. VERMES, or Worms Proper. 
 
 ANNELIDA (Small-rings) Lobworm, and almost all the marine worms. 
 KOTIFERA ( Wheel-bearers) Kotifers, Hydatina. 
 GEPHYRIA (Intermediates urchin-like) Sipunculus, Echinurus. 
 LUMBRICINA (Earth- worms) Earth-worms, Nais. 
 HIRUDINEI (Leeches) Leeches, Branchellion. 
 TURBELLARIA ( Turoellaries) Planaria, Kibbon- worms. 
 HELMINTHES (Gut-worms) Intestinal worms. 
 
 II. MOLLUSCA, subdivided into Molhisca and Molluscoida. 
 
 1. MOLLUSCA, or Shell-fish Proper. 
 
 CEPHALOPODA (Head-footed) Cuttle-fish, Octopus, Calamary, Nautilus. 
 PTEROPODA ( Wing-footed) Clio, Hyalsea. 
 GASTEROPODA (Belly -footed) Snails, Slugs, Whelks, Cowries. 
 ACEPHALA (Headless) Oysters, Mussels, Cockles, Shipworms. 
 BRACHIOPODA (Arm-footed) Terebratula, Lingula. 
 
 2. MOLLUSCOIDA, or Mollusc-like Animals. 
 
 . . . ( Biphora, Simple and Compound 
 TUNICATA (Coated, lut Shell-less) j * Ascidians. 
 
 POLTZOA (Compound animals)} 
 
 or VFlustra, Eschara, Plumatella, &c. 
 
 BRYOZOA (Moss-like animals) ) 
 
 III. RADIATA, or ZOOPHYTES Ray-like Animals. 
 
 ECHINODERMATA (Urchin-sJcinned) Sea-urchins, Star-fishes. 
 
 ACALEPH.E (Sea-nettles) Jelly-fish, Beroes. 
 
 POLYPI (Many-feet) Coral animals, Sea-anemones, Hydras. 
 
 IV. PROTOZOA, or LOWEST-LIFE -Globular Animals. 
 
 INFUSORIA (Infusories) Monads, Volvoces, Vorticella. 
 PORIFERA (Pore-bearers) Sponges, Fresh-water Sponges. 
 RHIZOPODA (Root-footed) Amoeba, Polythalamia (Foraminifera). 
 
 Such are the leading facts connected with the nature, 
 history, and arrangement of fossils. Much more might 
 have been stated respecting the positions in which they 
 occur and the geographical conditions which they thereby 
 
IMPORTANCE OF PALEONTOLOGY. 127 
 
 indicate, and a more detailed account might have "been 
 given of the chemical theories of petrifaction ; but enough 
 has been mentioned to convey to the reader a fair idea of 
 what fossils really are,* how they are formed, and how in- 
 dispensable their study is to the right interpretation of the 
 history of our planet. With this preliminary knowledge he 
 will peruse with greater zest and intelligence the Sketches 
 that follow ; and be better able to trace through the ascend- 
 ing stages of time that plan of vital development, the eluci- 
 dation of which has conferred on modern geology its high- 
 est interest and most enduring attraction. 
 
 NOT is it Geology alone that has benefited by the dis- 
 coveries of the palaeontologist. Botany and Zoology have 
 also acquired new interest, and the whole study of Life 
 assumed a broader and more philosophical bearing. Re- 
 stricted to existing forms, the biologist was often perplexed 
 by anomalies he could not solve, and for want of connec- 
 tions he could not trace ; but now that Palaeontology has 
 revealed its myriad forms, and exhibited a Scheme of Life 
 ever ramifying, yet ever interblending in its remotest rami- 
 fications, a clearer and steadier light has been thrown across 
 the path of his investigations. Even to the ordinary ob- 
 server of nature, how much more exalted the conceptions 
 of life which the science of palaeontology imparts ! How 
 
 * Fossils are sometimes arranged into the following classes -.First, 
 the actual substance ; secondly, the substance replaced by other sub- 
 stances ; thirdly, the cast or mould of the substance and this may be 
 either of the hard or of the soft substance ; and, fourthly, those fossils 
 which are now generally called physiological impressions, such as foot- 
 prints, being certain evidence of the animal having been there. Under 
 whatever class they may be arranged, their preservation will depend 
 partly on their own composition, partly on the nature of the stratum in 
 which they are imbedded, and partly on the chemical changes to which 
 that stratum may have been subsequently subjected. The investigation 
 of these particulars, however, belongs more to the professed palaeonto- 
 logist than to the readers of general geology. 
 
128 FOSSILS THEIR NATURE AND ARRANGEMENT. 
 
 marvellous that, numerous and varied as are the plants an 
 animals of the present day, they form but the merest fra< 
 tion of those that have successively adorned the earth 
 surface, each succeeding age being characterised by its ow 
 special forms, ascending and still ascending in variety an 
 complexity, yet all interwoven into one grand and ha: 
 monious Life-system ! 
 
THE OLD RED SANDSTONE. 
 
 INTEREST ATTACHED TO THE SYSTEM FEOM THE LABOURS OF AGASSIZ, 
 HUGH MILLER, AND OTHERS ITS POSITION IN WORLD-HISTORY 
 NATURE OF ITS STRATA HOW FORMED LOWER, MIDDLE, AND 
 UPPER FORMATIONS TERRAQUEOUS ASPECTS OF THE PERIOD ITS 
 FLORA AND FAUNA GIGANTIC CRUSTACEA VARIED AND ABUN- 
 DANT FISH-REMAINS GEOGRAPHICAL OR EXTERNAL CONDITIONS 
 OF THE OLD RED ERA ECONOMIC PRODUCTS DERIVED FROM THE 
 SYSTEM GENERAL REVIEW. , 
 
 THERE is the ring of antiquity in the very title of our sub- 
 ject, and yet old as the Old Red Sandstone may be, it is 
 younger by unnumbered ages than the Laurentian, the 
 Cambrian, and the Silurian. These earlier sediments were 
 converted into hard and crystalline strata, and upheaved 
 into dry land, long before it was deposited, and in many 
 instances they formed the hills and precipices from which 
 its materials were derived. Its place in the earth's chrono- 
 logy will be seen at a glance from the accompanying tabu- 
 lation but its interest as a formation arises less from its 
 antiquity than from the fact of its being the first in which 
 vertebrate remains decidedly occur, and from the circum- 
 stance that its history has been rendered classical by the 
 labours of some of our leading geologists. Hugh Miller's 
 * Old Red Sandstone,' Agassiz' Monograph of its fossil 
 fishes, the investigations of De la Beche, Murchison, Pan- 
 der, Huxley, the American States surveyors, and others, 
 have all contributed to this result; and during the last 
 
 i 
 
130 THE OLD BED SANDSTONE. 
 
 twenty years there are few systems whose names, at least 
 have been more familiar to the ordinary reader. But sinci 
 Agassiz elaborated his monograph, and Miller penned hi; 
 sketches, more extensive information has been obtained 
 and it is the object of the present chapter to display tha 
 newer knowledge in an intelligible and attractive form. 
 
 Arranging the rock-formations of the crust in chronolo 
 gical order, it will be seen that the Old Eed Sandstom 
 holds a middle place among the palaeozoic or primeval : 
 
 Quaternary or Recent, . ' I CAINOZOIC. 
 
 Tertiary, j (Recent Life.} 
 
 Cretaceous or Chalk, . \ MESOZOIC. 
 
 Oolitic or Jurassic, . V (Middle Life.) 
 Triassic Upper New Red Sandstone, J 
 
 Permian Lower New Red Sandstone, "j 
 
 Carboniferous, ., . . I PALEOZOIC. 
 
 Old Red Sandstone and Devonian, j (Ancient Life.) 
 
 Silurian, J 
 
 Cambrian, | Eozoic. 
 
 Laurentian, j (Dawn Life. ) 
 
 It does not belong to the very oldest, whose rocks have 
 been rendered crystalline by metamorphism, and whose 
 fossils have been sorely obliterated, but it is still very an 
 cient, and hence the interest that attaches to its old-worlc 
 forms, the outlines of which and their habits of life th< 
 pen of the palaeontologist can for the most part restore 
 The composition and origin of its strata are, generally 
 speaking, of easy determination. Conglomerates that were 
 once pebble and shingle beaches ; sandstones and flagstones 
 resulting from shore-formed sands; concretionary and coral 
 line limestones chiefly of animal origin ; and shales anc 
 marlstones, the consolidated muds of the deeper waters 
 Here and there we have bituminous shales, partly of anima! 
 and partly of vegetable impregnation ; and at still wider in- 
 
COMPOSITION AND ARRANGEMENT: 131 
 
 tervals thin seams of coal, like those of Gaspe* in Canada, 
 which seemed to have resulted from the growth and drift of 
 terrestrial vegetation. Wherever it occurs its sedimentary 
 character is sufficiently apparent, and though frequently 
 intersected by dykes and eruptive masses of basalt and fel- 
 stone, its stratified arrangement is never wholly obliterated. 
 The interstratifications of volcanic ash and igneous over- 
 flows observable in the Silurian system, and so frequent in 
 the Carboniferous, are rarely witnessed in connection with 
 the Old Eed Sandstone, as if the period, in the north of 
 Europe at least, had been one of comparative internal 
 quiescence. The system occupies considerable areas in 
 Europe, Asia, Africa, and both Americas, and is chiefly of 
 marine formation, though in some districts the total absence 
 of shells and corals would lead to the inference of fresh- 
 water conditions.* 
 
 We have said that the system occupies extensive areas 
 both in the Old and New World, and as no two rivers carry 
 down the same kind of debris, and no two seas receive ex- 
 actly the same kind of sediments, there will be considerable 
 diversity in the character of its rocks that is, in colour, 
 composition, and arrangement. Not only so, but as the 
 system is often of great thickness (12,000 feet or more), 
 there had been oscillations of the crust or new distributions 
 of sea and land during the long period of its deposition, 
 and thus its lower, middle, and upper portions differ even 
 in the same region, and sometimes lie unconformably upon 
 each other. It is for this reason that geologists speak of 
 
 * If the Old Red Sandstone of Scotland be of marine origin, it seems 
 inexplicable why no sea-shell, coral, or other zoophyte should have yet 
 been detected in any of its strata. Numerous as its fishes and Crustacea 
 undoubtedly are, and gigantic as some of them may appear, they may 
 have been inhabitants of estuaries or fresh- water seas ; and though the 
 general belief leans towards oceanic conditions, we are still without un- 
 mistakable proofs to support it. 
 
132 THE OLD BED SANDSTONE. 
 
 the Lower Old Bed," the " Middle Old Bed," and th< 
 " Upper Old Bed," each series differing not only in thi 
 composition of its strata, but in the character of its fossi 
 contents. But whatever its variations, there is, throughou 
 Europe at least, a marked prevalence of reddish-colourei 
 sandstones and slaty shales; hence the name "Bed" ii 
 allusion to this colour, and the term "Old" because i 
 lies beneath the coal-measures, and in contradistinction t 
 another series of red sandstones (the New Bed) that lie 
 above them. The system is also frequently termed th 
 "Devonian," because a portion of it is well developed i 
 Devonshire a term chiefly introduced by Sir Boderic 
 Murchison, to harmonise with his geographical nomencL 
 ture of Silurian and Permian. So much for name an 
 mineral composition ; let us now try to catch a glimpse < 
 the physical conditions under which it was deposited, an 
 the kind of life that peopled the land and waters. 
 
 Beyond a few scattered indications of the ancient disti 
 butions of sea and land, geology can obtain no more. Or 
 formation is so frequently overlaid by portions of later fo 
 mations ; so many portions have also been removed I 
 waste and denudation ; and perhaps still greater expansi 
 are hidden by the ocean, which covers nearly three-fourtl 
 of the earth's known surface, that we can merely indica 
 by disconnected patches the seas in which they were d 
 posited. In the case of the Old Bed Sandstone, whi< 
 occupies considerable areas both in the Old and New World 
 we cannot trace either the extent or configuration of i 
 seas, but we catch occasional glimpses of their shores in t] 
 conglomerates which must have formed their pebbly beach( 
 and in the worm-trails and burrows, the crustacean trad 
 the rain-prints, and sun-cracks on the surface of the san 
 stones which must have then spread out as shallow ai 
 alternately exposed sands. Strange revelations these of t' 
 
COMPOSITION AND ARRANGEMENT. 133 
 
 olden sea-shore ! the ripple of the receding tide, the wind- 
 ing trail of the shell-fish, the burrow and sand-cast of the 
 sea-worm, the patter of crustacean feet, the pittings of the 
 rain-shower, and the irregular shrinkage cracks of the sun- 
 baked shore-mud. And yet, as surely as these phenomena 
 are witnessed on the muds of existing sea-creeks, so surely 
 were they impressed on the shores of the Old Red Sand- 
 stone, were dried and hardened by the sun, covered over by 
 newer sediments, and thus preserved through all time as 
 evidences that nature's operations have been going forward 
 much in the same way from the remotest of periods. But 
 clear as these physical evidences are of the nature of the 
 Old Red sea-shore, there are facts connected with the great 
 extent and thickness of the pebbly (we may say bouldery) 
 conglomerates that are not so easy of explanation. We 
 know that in many parts of the world there are vast peb- 
 bly and shingly beaches, and that in some instances the 
 rounded blocks are hundreds of pounds in weight; but 
 there is something so peculiar in the aggregation of the Old 
 Red conglomerates, with their striated pebbles, their irre- 
 gular imbeddings of fine-grained sandstones and the like, 
 that they suggest the idea of masses floated and packed up 
 by shore-ice, and perhaps to some such condition their enor- 
 mous accumulations may yet be ascribed.* Be this as it 
 
 * Several years ago we appended the following note to a chapter on 
 the Old Red Sandstone (' Past and Present Life of the Globe'), and see 
 no reason yet to change our opinion : Whoever has examined the boul- 
 dery conglomerates of the Scottish Old Bed, with their large irregular 
 blocks, their peculiar unassorted aggregation, the nature of the cement- 
 ing matrix, and the frequent " nestings " or interlaminated patches of 
 fine argillaceous sandstone, must have had suggested to his mind the 
 idea of ice-action. And this notion must have been strengthened when 
 he turned to the sandstones, and found them imbedding angular frag- 
 ments of rock, shale, and even clay, which could scarcely have suffered 
 transport unless enclosed in drifting ice-floes. The paucity of terrestrial 
 life in certain areas seems also a further corroboration of the idea of 
 glacial influences a hypothesis which seems at first sight extremely 
 
134 THE OLD RED SANDSTONE. 
 
 may, its usual sandstones, flagstones, slaty shales, clayej 
 marls, and concretionary limestones are true water- formec 
 strata, and we perceive in their numerous alternations anc 
 varying compositions the recurrent sediments of open anc 
 free-flowing seas. 
 
 But if the mere lithological composition of its rocks car 
 thus throw light on the geographigal conditions of the Olc 
 Red Sandstone period, much more are we aided by a con 
 sideration of its fossils the plant-life and animal-life thai 
 peopled the lands and waters. Wherever it has been exam 
 ined, the flora appears to be of a lowly character sea-weeds 
 marsh or rush-like plants, clubmoss-like twigs, fronds o: 
 ferns, and less evidently, perhaps, drifted fragments o: 
 coniferous trees. We thus get a glimpse, as it were, o: 
 rocky weed-covered beaches, low marshy river -banks, o: 
 shady nooks and corners where fern and clubmoss luxuriate 
 and of higher uplands fitted for the growth of coniferse o: 
 pine-like trees. So far as known in Europe, the plants o 
 the Old Red generally appear in detached and drifted frag 
 ments, and rarely in such abundance as to form a bitumi 
 nous or coaly shale ; but in Canada the thin seams of coa 
 discovered by Dr Dawson would indicate not only a greatei 
 luxuriance, but even land areas on which they grew anc 
 died till the accumulated masses were sufficient to form sue 
 cessive layers of pure and crystalline coal. This is all tha 
 we learn of the dry land of the period from the vegetatioi 
 that clothed it. We know nothing of its extent or configu 
 ration, nothing of its hills or valleys, of its lakes or rivers 
 and are only left to infer from the nature and amount of th< 
 stratified sediments that the latter must have been botl 
 large and powerful. No true terrestrial creature insect 
 
 probable, though requiring for its final demonstration a much more pro 
 tracted and careful examination than the several phenomena have yel 
 received from geologists. 
 
FOSSIL FLORA AND FAUNA. 135 
 
 reptile, bird, or mammal has yet "been detected in its strata ; 
 and all that we know of its fauna is strictly aquatic, and 
 in all likelihood marine. 
 
 This fauna of the waters differs, of course, like the exist- 
 ing fauna, in different seas j but viewing the whole, and 
 taking the entire range of the system through its lower, 
 middle, and upper divisions, we have illustrations of the 
 following zoological orders : Corals, encrinites, and shells 
 occur abundantly in the limestones of Devonshire, but 
 similar organisms are altogether absent from the red sand- 
 stones of Hereford and Scotland, and to a great extent also 
 from the strata as developed in the north of Europe. 
 Whether this has arisen from some peculiarity in the sea- 
 bottom, or, as has been suggested, from the Scotch beds be- 
 ing chiefly of fresh-water origin, has not been satisfactorily 
 determined ; but the fact stands undoubted that up to the 
 present time no trace of a coral, an echinoderm (star-fish or 
 encrinite), or a shell-fish has been detected in the Old Red 
 Sandstone of Scotland. With what portion of the Scottish 
 beds the Devonshire strata may have been contemporane- 
 ously deposited has not yet been determined ; but clearly 
 it was not with the lower flagstones and bouldery conglom- 
 erates of Perth and Forfar. The Devonian corals and en- 
 crinites imply waters of genial temperature ; the bouldery 
 conglomerates the reverse : and in all likelihood the two, 
 though classed under the same system, were chronologically 
 separated by ages.* But while the coral-building zoophytes, 
 
 * This is not, perhaps, the place to enter into the question of co-ordi- 
 nation ; but we cannot refrain from repeating our conviction, expressed in 
 1856, that the term " Devonian " can never be legitimately substituted 
 for that of " Old Red Sandstone. " We have examined the strata of Devon- 
 shire from north to south and from east to west, and instead of finding 
 the equivalents of the Scottish Old Red we discovered in the Northern 
 division one set of rocks that should be ranked with the lowermost Car- 
 boniferous, and in the Southern another that was perhaps contemporane- 
 ous with portions of the middle and upper Old Red. At all events, the 
 
136 THE OLD BED SANDSTONE. 
 
 the encrinites, star-fish, and shell-fish seem thus to have 
 had a partial distribution in the waters of the period, the 
 annelids or worms, the Crustacea, and the fishes abounded 
 throughout, and this in numerous and varied specific aspects. 
 Trails and burrows occur in every division of the system, 
 from mere thread-like windings on the surfaces of the strata 
 to burrows in the sandstones as thick as a man's arm ; and 
 Crustacea (trilobites and eurypterites) throng especially the 
 lower division in strange and often gigantic forms. Indeed 
 the huge lobster-like forms of these eurypterites eurypterus. 
 pterygotus, andstylonurus with their long segmented bodies 
 void of appendages, and their broad carapaces, like the king- 
 crab's, with limbs and jaws beneath, are characteristic fea- 
 tures of the Old Red fauna. Ranging from three to six feel 
 and upwards in length, with their toothed prehensile claws 
 and oar-like swimming feet, no crustacean form has since 
 equalled them in size, though few, perhaps, are more rudi- 
 mentary in their structure. Like most articulated animals, 
 these Crustacea seem to have been readily dismembered b} 
 decay, hence their limbs and segments are frequently detached 
 and scattered ; and yet so wonderful has the preservative 
 process been, even in the midst of dismemberment and de- 
 cay, that their egg-packets, or masses of spawn (known as 
 Parka decipiens, from Parkhill in Fife, where first detected) 
 are common throughout the lower flagstones. How imper 
 ishable the record, could we only lay it bare, that nature 
 keeps of her bygone aspects and operations ! 
 
 rocks of Devonshire as a whole do not represent the Old Red Sandstone o 
 Scotland, of Northern Europe, and North America as a whole ; and henc< 
 the inappropriateness of Devonian as a substitute for the earlier anc 
 more descriptive term Old Red Sandstone. The designation may yet bi 
 found to be an appropriate one for a set of formations that apparently 
 lie between the true Old Ked and the Carboniferous proper ; but to em 
 ploy it as synonymous with what was originally understood as the Olc 
 Eed Sandstone system is, in our opinion, an error and misapplication. 
 
FOSSIL FLORA AND FAUNA. 137 
 
 Strange and gigantic, however, as are these early crusta- 
 ceans, they are comparatively recent discoveries and but lit- 
 tle known, and it is chiefly through its fossil fishes, their 
 numbers, variety, and beauty of preservation, that the sys- 
 tem has become the subject of popular interest and investi- 
 gation. As might be anticipated, these fishes differ consid- 
 erably in the different portions of the system those of the 
 lower being chiefly small or moderate sized, covered with 
 minute enamelled scales, and very generally armed with fin- 
 spines ; those of the middle portion, again, being fewer in 
 number but larger in size, and protected by broad sculptured 
 scales or plates ; while those of the upper zone, though still 
 covered with enamelled scales, assume more the character 
 of ordinary fishes, both in their size and configuration. 
 Throughout the whole, the bony enamelled scales and 
 plates (the exo-skeleton of anatomists) is the prevailing 
 feature, and all without exception are characterised by the 
 heterocercal or unequally-lobed tail the upper lobe extend- 
 ing in a bold and prolonged sweep, as in the existing sharks 
 and dog-fishes. In Britain the great repositories of Old 
 Red fishes have hitherto been the lower shales of Forfarshire, 
 the lower and middle flagstones of Caithness and Cromarty, 
 the middle sandstones of Moray and Banff, and the upper 
 yellow sandstones of Dura Den in Fifeshire. In some of 
 these localities they are crowded together in shoals, with every 
 fin and scale in place as if overtaken and entombed by some 
 sudden catastrophe ; and we have seen a slab about the size 
 of an ordinary writing-table, raised in Dura Den, with up- 
 wards of fifty individuals upon it, belonging to five separate 
 genera, and varying in length from ten to thirty inches.* 
 
 * At the instance of the British Association, and under the superin- 
 tendence of the late Dr Anderson, of Newburgh, and the Author, this 
 and numerous other slabs of nearly equal richness were raised from 
 Dura Den in 1860 and 1861 ; and could they have been rendered readily 
 portable, slabs of double these dimensions, and with treble the number 
 
138 THE OLD RED SANDSTONE. 
 
 It would be out of place in a sketch of this nature to 
 enter into technical details, but it may be mentioned as of 
 some value, and not difficult of comprehension, that the 
 fishes of the lower zone, with fin-spines and minute lozenge- 
 shaped or but slightly-rounded scales, are known by such 
 names as acanthodes (spiny), cheiracanthus (fin -spine), 
 diplacanthus (double -spine), isnacantlius (slender -spine), 
 parexus (ladder -spine), and so forth, in allusion to the 
 character of their spines ; that those of the same zone 
 having the head enclosed in a bony shield or series of 
 plates, are named cephalaspis (buckler-head) and pteraspi* 
 (buckler -wing); that those of the middle zone having 
 their bodies enclosed in a bony case, somewhat like the 
 living trunk -fish, are known as coccosteus (berry -bone), 
 and 'pterichthys (wing-fish) ; while those of the same zone 
 with ordinary scales and fins are spoken of as osteolepis 
 (bony-scale), dipterus (double-fin), and diplopterus (twin-fin): 
 and that those of the upper zone, with their variously sculp- 
 tured scales and head-plates, are known as holoptycTdus (all- 
 wrinkle), glyptolepis (carved-scale), glyptolcemus (carved- 
 throat), and other such names, having allusion to some well- 
 marked and obvious distinction. There is nothing very 
 puzzling in the names once their meaning has been explained 
 and the objects to which they refer have been examined. 
 Indeed the local names for the living fishes of our own 
 coasts are often as puzzling and far less euphonious. Go to 
 Cornwall and you hear one name, cross to Lincoln and yon 
 have another ; proceed to Fife and you hear a third, or north- 
 ward to Wick and you have a fourth all requiring ex- 
 planation, and, till explained, as unintelligible as the much- 
 vituperated technicalities of the palaeontologist. 
 
 of specimens, could have been easily obtained. The genera were chiefly 
 HoloptycMiis, Glyptolepis, Phaneropleuron, Glyptolcemus, Glyptopomus, 
 and Pterichthys. 
 
REVIEW OF THE SYSTEM. 139 
 
 Beyond fishes, we know for certain of no higher life dur- 
 ing the period of the Old Red Sandstone. It is true that 
 remains of reptiles and reptilian footprints have been found 
 in the sandstones of Lossiemouth and Cummingstone in 
 Morayshire, but there are doubts about the age of these 
 strata whether they be truly uppermost Old Red, or be- 
 long perhaps to the ISTew Red or Triassic. In this state of 
 uncertainty it may be generalised (provisionally, of course, 
 and having this doubtful instance fully in view) that the 
 flora of the Old Red period, scantily and obscurely de- 
 veloped, consists mainly of sea-weeds, marsh-plants, club- 
 mosses, ferns, and coniferous-looking trees ; and that its 
 fauna, on the other hand, taking all the divisions of the 
 system as known in Europe and America, consists of corals, 
 encrinites, star-fishes, polyzoa, shell-fish, Crustacea, and fishes. 
 We have thus no insects, no undoubted instance of reptiles, 
 no birds, no mammals. No doubt the record is imperfect, 
 and it cannot for a moment be supposed that geologists in 
 the few scattered patches they have examined have detected 
 all, or nearly all of the Old Red Sandstone organisms. In- 
 deed, the existence of those already discovered necessarily 
 implies the presence of others on whom they preyed, or by 
 whom they were in turn preyed upon ; and the links we 
 have discovered in the chain of life, separated as they are, 
 prove the existence of the missing ones as clearly as if they 
 had been displayed before us. Still, notwithstanding all 
 these facts and logical inferences, the flora and fauna of the 
 Old Red Sandstone curiously coincide in the main with all 
 that geology knows of the chronological development of life 
 on our globe, and we perceive in its discovered forms the 
 gradually-ascending steps in the great systemal scale of 
 vitality. 
 
 Such is a brief review of the Old Red Sandstone a 
 
140 THE OLD RED SANDSTONE. 
 
 period during which vertebrate life made its decided appear- 
 ance on our planet, and during the continuance of which 
 several new distributions of sea and land were effected. We 
 say new distributions of sea and land, for there is no other 
 way of accounting for the differences that exist between its 
 lower, middle, and upper portions without supposing that 
 they were deposited in seas of different depths, and in seas 
 that derived their sediments from different directions. And 
 as these varying distribuions of sea and land necessarily 
 imply variations in climate and external conditions, we can 
 readily perceive how the plants and animals of the lower 
 portion differ from those of the middle, and these again 
 from those of the uppermost division. Nature is incessant 
 in her operations, and while the system of Waste and Re- 
 construction, described in our Sketch No. 2, endures, new 
 distribution of sea and land will be brought about in the 
 course of ages, varying conditions of climate will be effected. 
 and under the new conditions, some plants and animals 
 will shift their ground, some will flourish more luxuriantly, 
 and others again become altogether extirpated. But this^is 
 not all : under these ever-varying conditions, and as time 
 rolls on, some forms of life seem to run their appointed 
 course and die out, and other and newer forms, in the 
 course of creation, seem to make their appearance. It ig 
 thus that some forms of life are peculiar to the Old Eed 
 Sandstone that is, do not occur in earlier systems, and are 
 not found beyond the close of the period. Many forms oi 
 coral, several genera of shell-fish, some trilobites, the gigan- 
 tic crustaceans, pterygotus arid stylonurus, the cephalaspis. 
 pteraspis, coccosteus, pterichthys, and other fishes, have 
 never been detected beyond the limits of the Old Red' for- 
 mation. They came in during the system, and died ou1 
 before its close; thus implying not only long lapses oJ 
 growth, and reproduction, and decay, but an onward marcl] 
 
GENERAL REVIEW. 141 
 
 in that creative process by which the world has been 
 peopled by different and higher races during the advancing 
 periods of its geological history. How wonderful this newer 
 knowledge of life which geology imparts ! how marvellous 
 the ever-ascending yet never-completed scheme of vitality 
 it reveals ! To our forefathers the life of the present era 
 was but a repetition of the life of former ages ; to us the 
 life of the present is but a passing aspect, differing from the 
 thousand aspects that went before, but inseparably bound 
 up with them in one great scheme of ever-varying yet ever- 
 widening development. 
 
 Such once more is the Old Red Sandstone, a system that 
 owes its interest much more to its scientific than to its 
 economic importance. Indeed, with the exception of build- 
 ing-stones used for local purposes, some indifferent lime- 
 stones, and paving-flags, such as those of Caithness andForfar, 
 there are no rocks of any commercial value among its strata ; 
 and the only accidental minerals we are aware of are oc- 
 casional poorish veins of galena, veins of baryta, salt springs 
 like those of North America, and the pebbles of agate, 
 carnelian, and the like (Scotch pebbles), obtained from the 
 amygdaloidal trap-rocks that traverse the system. Its chief 
 interest centres round its fossil fishes and Crustacea, sub- 
 jects rendered popular now more than twenty years ago by 
 the writings of Hugh Miller and Agassiz, and still attracting 
 attention by the newer forms that are year after year made 
 known by the labours of younger geologists.* And surely 
 what geologists are labouring to reveal, the man of ordinary 
 intelligence may make some effort to comprehend and en- 
 
 * We allude in particular to the labours of Professor Pander among 
 the Old Red fishes of Russia ; the numerous discoveries of new crusta- 
 ceans and fishes in the flagstones of Forfarshire by Mr Powrie ; and 
 the long-continued observations of Dr Gordon among the sandstones of 
 Moray and Ross-shire. 
 
142 THE OLD BED SANDSTONE. 
 
 joy. It must indeed be a dull and incurious mind thai 
 cannot be induced to take an interest in the history of tht 
 . world he inhabits, and to trace in its formations the record 
 of operations which took place, and the nature of beings 
 that lived and died, thousands of ages before the humar 
 race was created to become participators in the same ever 
 varying and ever-advancing scheme of vitality. Astronomy 
 may be a loftier theme, but the loftiness of its topics onlj 
 renders them the colder and more remote. Geology, on th( 
 other hand, has ever an immediate and human interest 
 The Earth's Past is inseparably interwoven with her Pre- 
 sent ; that which now lives is intimately associated in plar 
 and relationship with that which lies fossil in the rocks 
 beneath us; this plan has been steadily evolving during 
 untold ages ; man's own history is but part and parcel oJ 
 that plan ; and surely whatever tends to exalt our concep- 
 tions of creation can never tend to weaken our reverence 
 for the power, wisdom, and goodness by which it is directed 
 and sustained. 
 
COAL AND COAL-FORMATIONS. 
 
 COAL, ITS ORIGIN AND FORMATION MINERALISED VEGETATION 
 RECENT PEAT-GROWTHS TERTIARY LIGNITES SECONDARY AND 
 PALAEOZOIC COALS PRIMARY ANTHRACITES AND GRAPHITES THE 
 COALS AS A MINERAL FAMILY CONVERSION OF VEGETABLE SUB- 
 STANCES INTO COAL ITS VARIOUS STAGES PEAT, LIGNITE, COAL, 
 ANTHRACITE, AND GRAPHITE CHARACTERISTICS OF THESE RE- 
 SPECTIVE STAGES IMPORTANCE OF COAL TO CIVILISED COUNTRIES 
 SPECIAL VALUE OF, TO GREAT BRITAIN. 
 
 THERE is no mineral in the crust of the earth more essential 
 to modern civilisation than coal, and there is, perhaps, no 
 geological technicality more frequently made use of than 
 " Coal-formation," and yet how few have a rational or in- 
 telligent conception of either ! Every man and woman in 
 the British Islands is less or more acquainted with the ordi- 
 nary aspects of coal and its uses, and yet not one in a hun- 
 dred, perhaps, could give the commonly received explanation 
 of its nature and origin. Most people are aware that coal 
 is obtained by mining in rocks known as the Coal-forma- 
 tion, and yet how few know anything of the nature of 
 these rocks, how they were aggregated, or by what means 
 coal was formed along with them ! It is true that men of 
 science have their differences about these things, as they 
 have about many other matters ; but these differences are 
 for the most part trivial, and do not affect the general belief 
 either as to the nature of coal or the processes by which it 
 was aggregated. It is to state these beliefs in a simple and 
 intelligible way that we attempt the present Sketch, and 
 
144 COAL AND COAL-FORMATIONS. 
 
 our main object will be to exhibit the points upon which 
 geologists are generally agreed, rather than to distract the 
 non-scientific reader with the minutiae upon which some of 
 them still continue to differ. 
 
 What is coal 1 is a question more satisfactorily answered 
 by a little roundabout explanation than by a direct reply. 
 To say that coal is altered and mineralised vegetable matter 
 is true ; but the definition is too curt to be readily intelli- 
 gible. Every one knows something of peat and peat-mosses ; 
 well, this peat is simply coal in its first stage of develop- 
 ment. Were the peat-moss submerged and covered over 
 by deposits of mud and clay and sand, it would in course 
 of time undergo important chemical changes, by which 
 part of its gaseous contents (oxygen, hydrogen, &c.) would 
 be discharged, and the mass reduced to a compact coaly 
 substance known as lignite or brown-coal. Such brown- 
 coals are abundant in many countries (Germany, Austria, 
 New Zealand, &c.), and worked for economical purposes; 
 and were they subjected to still further changes they would, 
 in course of ages, become converted into shining stony coals 
 like those which are now raised so largely from the coal- 
 fields of Great Britain. The truth is, coal occurs in the 
 earth's crust in every stage of development, from the peat- 
 mosses and swamp-growths still in process of accumulation 
 on the surface, down through the tertiary brown-coals to 
 the bituminous stone-coals of the secondary and primary 
 periods, and from these again down to the still older non- 
 bituminous anthracites and graphites. All, in fact, have 
 had a similar origin. They are mere vegetable masses that 
 have undergone different degrees of mineralisation the 
 recent vegetable full of volatile matters, the lignites less 
 so, the bituminous coals giving off smoke and flame, the an- 
 thracites barely smoking, and the graphites masses of pure 
 
THEIR RELATIVE AGES. 145 
 
 debifnunenised carbon. They are all coals, and belong to the 
 same family those in the younger formations still retaining 
 much of their vegetable structure and full of volatile matter, 
 while those in the older formations have seemingly lost all 
 traces of structure, and have been all but deprived of their 
 volatile constituents. But even where no structure is ob- 
 vious to the naked eye, it can generally be rendered apparent 
 by submitting thin transparent slices to the microscope. 
 By this means the vegetable origin of the most compact and 
 glistening coal is often revealed as clearly as the tissues in 
 living plants, and thus the observer is enabled to determine 
 not only the organic nature of the mass, but the botanical 
 peculiarities of the order concerned in its formation. 
 
 Since coal is thus merely altered and mineralised vegetable 
 matter, and since vegetation must have nourished more or 
 less during every period of the earth's history, there must 
 be coals of some kind or other occurring in every geological 
 formation. It may appear more abundantly and more 
 availably in one formation than in another ; still, believing 
 in the uniformity of nature's operations, we must be pre- 
 pared to admit its presence in every stratified system, and 
 not to regard it, as was at one time done, as a product 
 peculiar to the Carboniferous era. Arranging the forma- 
 tions in chronological order, we have their coals, or rather 
 the coal family, associated with them in something like 
 the following conditions : 
 
 Quaternary, Peats. 
 
 Tertiary, Lignites. 
 
 Cretaceous, Lignites and Coals. 
 
 Oolitic, Coals. 
 
 New Red Sandstone, Coals. 
 
 Carboniferous, Coals and Anthracites. 
 
 Old Red Sandstone, Coals and Anthracites. 
 
 Silurian, Anthracites. 
 
 Cambrian, Anthracites and Graphites. 
 
 Laurentian, Graphites. 
 
 E 
 
146 COAL AND COAL-FORMATIONS. 
 
 It is true that in the older formations we have but a very 
 scanty exhibition of coaly substances, and it is equally true 
 that hitherto the most extensive developments have been 
 found in strata of Carboniferous age ; but it is nevertheless 
 the fact that coal-fields of great value occur in the oolitic 
 and cretaceous rocks, and that brown-coals are common in 
 almost every tertiary district. It may render the subject 
 more intelligible and attractive if we take the formations 
 seriatim beginning with the recent and apparent, and 
 working down through the older and more obscure. 
 
 The coals of the present day are the peat-mosses, the 
 swamp-growths, and the vegetable drifts borne down by 
 rivers and deposited in their estuaries. We have no means 
 of ascertaining the extent or thickness of vegetable drifts, 
 though some, like the " Rafts" of the Mississippi, are of con- 
 siderable thickness and extent; but we know that large areas 
 in all the temperate and colder latitudes are occupied by 
 peat-mosses and swamp-growths the lake region of North 
 America, Canada, the Southern States, Siberia, Northern 
 Europe, Denmark, Holland, and our own islands.* These 
 are often of great thickness, and date from the growth of 
 the current year to the very dawn of the Quaternary epoch ; 
 loose and turfy above, firm and peaty a few feet down, 
 and at greater depths black and dense as some varieties of 
 lignite. Indeed, we have seen varieties of Dutch peat taken 
 at 30 feet deep indistinguishable from some lignites ; and 
 
 * We have no reliable statistics of the extent and thickness of peat- 
 mosses either in Europe, Northern Asia, or North America ; but in the 
 recently published Eeport on the Geology of Canada by Sir William 
 Logan, a number of details are given, from which we learn that upwards 
 of 300 square miles of that country are occupied by peat-mosses varying 
 from 3 to 30 feet in thickness. If such be an approximation to the 
 amount of peaty surface in the surveyed portion of Canada, the amount 
 in the whole of British North America, Northern Europe, and Northern 
 Asia, must be something enormous. 
 
PEATS AND LIGNITES. 147 
 
 all that seems necessary to convert them into true brown- 
 coals are the cover and pressure of superincumbent strata, 
 and time sufficient to effect those further chemical changes 
 to which lignites and brown-coals have been generally sub- 
 jected. We see, therefore, in the compressed vegetable 
 matter we call peat, and which has been formed by the 
 growth and decay of certain plants* during many cen- 
 turies, the first stages of coal, and when we come to con- 
 sider the older formations, we shall find that many of their 
 coal-seams have had a similar origin. And just as this peat 
 is sometimes earthy and mingled with stony matter that has 
 been washed into the swamps and hollows by rains and 
 rivers, so we may expect some of the old coals to contain 
 similar impurities, and to be less valuable as fuel. 
 
 The next and older series of coals embraces the lignites 
 or wood-coals, the brmcn-coals and board-coals of the Ter- 
 tiary strata. As these names imply, their woody or vege- 
 table texture is still apparent, and they are generally of a 
 brown or earthy hue, compared with the black and glisten- 
 ing lustre of the coals of the older formations. Alternating 
 with clays, marls, sands, and gravels, they have evidently 
 been formed partly in fresh-water lakes and swamps, and 
 partly in areas that have been submerged and covered over 
 by marine deposits. In some instances they are earthy, 
 and composed of the drifted trunks and branches of trees ; 
 and in others the submerged and fallen forest-growth can 
 be traced as clearly as it can be in some of the shallower 
 peat-beds of Scotland. Most of these lignites, whether as 
 once worked at Bovey in Devonshire, or as still worked in 
 Germany, Prussia, Austria, New Zealand, and other coun- 
 tries, may be described as coal in its second stage of 
 consolidation and mineralisation. In the mine they are 
 * See Sketch entitled "Recent Formations." 
 
148 COAL AND COAL-FORMATIONS. 
 
 soft, Ml of water, and easily cut ; and when brought to 
 the surface, dry and break up, and soon crumble down 
 under the influence of the weather. They are also less 
 regular in their bedding than the older coals thickening 
 and thinning capriciously; but in some instances their 
 bedding is regular and continuous over considerable areas, 
 and their quality is so much improved that they are scarcely 
 distinguishable from ordinary coal. One remarkable in- 
 stance of this kind, the Zsil valley in Transylvania, was 
 visited in 1862 by Professor Ansted, who found not lig- 
 nite, but coal differing little from some varieties of English 
 coal, lying in regular beds of great thickness, and alternat- 
 ing with shales, ironstones, and grits. Of course, all the 
 vegetable accumulations of the Tertiary system are not 
 precisely of the same age, nor have they been deposited 
 under the same conditions, and thus we may expect to find 
 differences among them, just as among the coals of the older 
 formations. And hence it happens that some of these 
 lignites are scarcely fit for pottery or brick-kiln purposes, 
 while others (certain compact and lustrous varieties) are 
 advantageously used for locomotive engines and for metal- 
 lurgical operations. 
 
 Although seams of lignite are occasionally found in the 
 Cretaceous and Oolitic systems, yet, generally speaking, the 
 Secondary strata the Chalks, Oolites, and New Eed Sand- 
 stones are characterised by the presence of true coals. 
 The seams may not be continuous over extensive areas 
 that is, may thicken and thin somewhat capriciously but 
 still mineralisation of the mass is complete, and we are 
 presented with bituminous coals of varying commercial 
 value. Such Secondary coal-fields occur at Brora and 
 Whitby in Britain ; at Fiinf kirchen and Oravicza in Aus- 
 tria; at Burdwan, Nerbudda, and other districts in In- 
 
SECONDARY COAL-FIELDS. 149 
 
 dia ; in Burma, Borneo, and Labuan ; in New Zealand ; 
 Natal in South Africa; Vancouver Island, and British 
 Columbia ; at Eichmond in Virginia ; and in all likelihood 
 in other districts that have not yet been sufficiently sur- 
 veyed. These coals, so far as they have been geologically 
 examined, have been accumulated precisely like the peat- 
 mosses, swamp-growths, and vegetable-drifts of the present 
 day. Some have evidently grown in situ, and accumulated 
 in great thickness and purity for ages ; in others the growth 
 has been interrupted by overflowings of the water, and 
 earthy layers are not unfrequent in the mass; while in 
 others, again, the mass is so irregular in thickness and 
 composition, that it at once recalls the idea of drift and 
 heterogeneous deposition. Whatever the thickness or 
 composition, they are true bituminous coals, thus disprov- 
 ing the belief which was generally entertained some twenty 
 or five-and-twenty years ago, that all true coal was a product 
 of one geological epoch only, and necessarily belonged to 
 the Carboniferous formation. On this point we can offer 
 nothing more convincing than the following extract from 
 Sir Charles LyelTs description of the Eichmond coal-field 
 in Virginia : " These Virginian coal - measures are com- 
 posed of grits, sandstones, and shales, exactly resembling 
 those of Older or primary date in America and Europe, and 
 they rival, or even surpass, the latter in the richness and 
 thickness of the coal-seams. One of these the main 
 seam is in some places from 30 to 40 feet thick, com- 
 posed of pure bituminous coal. On descending a shaft, 
 800 feet deep, in the Blackheath mines in Chesterfield 
 county, I found myself in a chamber more than 40 feet 
 high, caused by the removal of the coal Timber props, 
 of great strength, supported the roof ; but they were seen 
 to bend under the incumbent weights. The coal is like 
 the finest kinds shipped at Newcastle, and when analysed 
 
150 COAL AND COAL-FOKMATIONS. 
 
 yields the same proportions of carbon and hydrogen a 
 fact worthy of notice when we consider that this fuel has 
 been derived from an assemblage of plants very distinct 
 specifically, and in part generically, from those which have 
 contributed to the formation of the ancient or palseozoic 
 coal." 
 
 " It is true, however," says one of the most experienced 
 and practical of British geologists (Professor Ansted), 
 "that the great coal-fields of England, of Belgium, of 
 Spain, of France, and of North America, besides those of 
 Bohemia, Moravia, and the Rhine, of Russia and China, 
 and probably of Australia, belong to the oldest or palaeozoic 
 rocks, and that for some reason that may perhaps be better 
 understood at a future time than it now is, these deposits 
 are more regular, more uniform over large areas, and in 
 that sense more to be depended upon, than those of newer 
 date." * In other words, they belong to the Carboniferous 
 system, that great series of limestones, sandstones, shales, 
 ironstones, and coals, which has hitherto yielded the main 
 supplies of mineral fuel, and to which Britain owes so 
 much of her mechanical superiority and commercial great- 
 ness. As this system will form the subject of a separate 
 Sketch, we need only here observe that its coals occur in 
 many seams, of every thickness, from a few inches to forty 
 feet , of all degrees of purity, from earthy masses that 
 
 * There can be no doubt that the difference here alluded to has arisen, 
 partly from the peculiar distribution of sea and land during the Carbon- 
 iferous era, which permitted over extensive areas a moist, genial, and 
 equable climate, and partly from the peculiar character of the vegetation 
 of the period, which seems to have been at once of rapid growth and of a 
 kind eminently fitted for preservation. Physical conditions like a moist, 
 genial, and equable climate may recur in the course of nature, but the 
 Life of each geological system is peculiar, and vanishes with the period 
 to which it belongs. The Carboniferous flora disappeared with its epoch ; 
 and no flora equally fitted for the formation of coal has since recurred or 
 may ever again recur in the progressional course of creation. 
 
PRIMARY COAL-FIELDS. 151 
 
 can scarcely be ignited, to clear bituminous searns that 
 burn leaving scarcely a trace of ashes ; and fitted for 
 every economical purpose household fuel, gas -making, 
 oil -distillation, steam -raising, smelting, and metal- work- 
 ing. Like other coals, the thickest, the purest, and most 
 continuous seams have evidently grown and accumulated 
 in situ; those imbedding stony and earthy layers have 
 been interrupted in their accumulation ; and others, again, 
 less regular and continuous in thickness and mingled 
 more with extraneous impurities, have apparently been 
 formed of drift and water-logged vegetation. In lakes, 
 in estuaries, and along great shallow sea-reaches, the flora 
 of the Carboniferous era flourished for ages, the land now 
 sinking, now rising, but on the whole subsiding, to receive 
 the vast thickness of sediments which compose the system. 
 Read in the light of what is now taking place at the present 
 day, there is nothing abnormal or preternatural in the 
 Coal-formation, and we behold in its various coals merely 
 the peat - growths, swamp - growths, jungle -growths, and 
 vegetable-drifts of the period, compressed and mineralised 
 during the lapse of ages. The caking-coals, splint-coals, 
 cannel-coals, and anthracites or stone-coals of the miner are 
 merely different expressions of this mineralisation or meta- 
 morphism different conditions of deposit, as rapid covering 
 up, exposure to decay, nature of vegetation, and compact- 
 ness of overlying strata, all affecting the ultimate quality 
 of the coal. If much earthy matter has mingled with the 
 vegetable mass during its aggregation, the coal will be stony 
 and impure ; if the vegetable mass has been rapidly covered 
 up by retentive muds and clays (now converted into shales 
 and fire-clays), the coal will likely be soft and highly bitu- 
 minous ; if the superincumbent stratum be open and porous, 
 so as to admit the escape of volatile matters, the coal will 
 in all likelihood be hard, dry, and less bituminous ; and if 
 
152 COAL AND COAL-FORMATIONS. 
 
 the vegetable mass has undergone extreme chemical change, 
 or has, as a coal, "been subjected to the heat of igneous rocks, 
 it will less or more be deprived of its gaseous elements and 
 converted into an anthracite. And thus, and thus only, can 
 the great variety of coals occurring in the paleozoic coal- 
 fields of Europe and North America be satisfactorily ac- 
 counted for. 
 
 Beyond the Carboniferous system coals become rare and 
 comparatively unimportant. It is true that in some dis- 
 tricts we cannot fix any very sharp line of demarcation 
 between the Coal-formation and the Old Red Sandstone, but 
 generally speaking the two systems are sufficiently distinct, 
 and it is curious that up to the present time no coal-seams 
 of any thickness have been detected in the latter. Indeed, 
 with the exception of some insignificant bands described 
 by Principal Dawson as occurring at Gaspe in Canada, the 
 Old Red Sandstone is altogether barren of coal, though 
 vegetable fragments are scattered^in some abundance through- 
 out its shales and flagstones. In the Silurian and more 
 highly metamorphosed Cambrian and Laurentian strata we 
 have thin bands and irregular patches of anthracite and 
 graphite ; but though these are generally ranked with the 
 coal family, their vegetable structure has been so obliterated 
 that we cannot say whether they have been formed from 
 terrestrial or marine vegetation, or indeed whether graphite 
 is always certainly of organic origin. 
 
 Here, then, we perceive that Coals, or minerals of the 
 Coal Family, occur in all formations, from the accumulations 
 now going forward on the earth's surface down through 
 every stratified system, whether belonging to tertiary, second- 
 ary, or primary epochs. From peat we pass to lignite, from 
 lignite to true coal, from coal to anthracite, and from anthra- 
 
VARIETIES OF COAL. 153 
 
 cite to graphite. All are but compressed and chemically 
 altered masses of vegetation, the slow fermentation or dis- 
 tillation of which results in the gradual expulsion of the 
 gaseous or volatile portions, and in the retention of the 
 carbonaceous or coaly residue.* The following tabulation 
 exhibits, proximately, this gradation of chemical change by 
 which wood is converted into peat, peat into lignite, lignite 
 into coal, coal into anthracite, and anthracite into graphite : 
 
 (At 212.) Carbon. Hydrogen. Oxygen. Nitrogen. 
 
 Wood 4854 610 35-45 
 
 Peat 5666 5 9 1833 24 1 6 
 
 Lignite 5670 37 1327 10 113 
 
 Coal 70-92 2-6 18 0-2 314 
 
 Anthracite 7494 14 03 trace 17 
 
 Graphite 80-98 ... 17 
 
 Here it will be observed that the gaseous substances, 
 hydrogen and oxygen, so abundant in recent wood and 
 peat, gradually diminish as the mass becomes more and more 
 mineralised, till at length they disappear and leave in con- 
 sequence a gradually-increasing residue of carbon in the 
 true coals, anthracites, and graphites. Like all mixed rocks, 
 however, coal presents itself in many varieties. We can- 
 not conceive of vegetable matter (whether drifted or grown 
 
 * According to M. Fremy, the following are the degrees of alteration 
 of woody tissue : 1. Turf and Peat. Characterised by the presence of 
 ulmic acid, and also by the woody fibres or the cellules of the medullary 
 rays, which may be purified or extracted in notable quantities by means 
 of nitric acid or hydrochlorites, in which they are insoluble. 2. Fossil 
 Wood or Woody Lignite. This, like the preceding, is partially soluble 
 in alkalies, but its alteration is more advanced, for it is nearly wholly 
 dissolved by nitric acid and hydrochlorites. 3. Compact or Perfect Lig- 
 nite. This substance is characterised by its complete solubility in hydro- 
 chlorites and in nitric acid. Alkaline solutions do not in general act on 
 perfect lignites. Reagents in this variety show a passage of the organic 
 matter into coal. 4. Coal. Insoluble in alkaline solutions and hydro- 
 chlorites. 5. Anthracite. An approximation to graphite ; resists the 
 reagents which act on the above-mentioned combustibles, and is only 
 acted on by nitric acid with extreme slowness. 
 
154 COAL AND COAL-FORMATIONS. 
 
 in situ) being associated with sedimentary strata without 
 its being mingled more or less with the earthy impurities 
 of these sediments. These impurities, according to their 
 amount, must necessarily confer on different coals different 
 structures, different aspects, arid different qualities. Be- 
 sides, varieties will also arise from the conditions of the 
 vegetable mass 4 itself, according as it may have been im- 
 bedded while fresh or been long exposed to atmospheric 
 decay, according as it may have been suddenly covered up 
 or long exposed to maceration and comminution in water, 
 and notably also according to the nature of the plants 
 composing the mass. These varieties, according to their 
 structure, texture, and qualities, are generally known as 
 coking-coal, which is soft and tender in the mass, like that 
 of Newcastle, and swells and cakes together in burning ; 
 splint or slate coal, which is hard and slaty in texture, 
 like most Scotch coals, and burns free and open cannel or 
 parrot coal, which is compact and jet-like in texture, spirts 
 and crackles when thrown suddenly on the fire, but when 
 ignited burns with a clear candle-like flame, and from its 
 composition is chiefly used in gas-manufacture ; and coarse, 
 foliated, or cubic coal, which is more or less soft, breaks up 
 into large square blocks, and contains in general a large per- 
 centage of earthy impurities. Between these varieties there 
 is, of course, every gradation coals so pure as to leave only 
 one or two per cent of ash, others so mixed as to yield from 
 ten to thirty per cent, and many so impure as to be unfit 
 for fuel, and so to pass into shales more or less bituminous.* 
 
 * As bituminous shales are now so extensively mined for the distillation 
 of paraffin, it may be of use to advert to some distinctions that subsist be- 
 tween them and the coals properly so called. A coal, though often contain- 
 ing a considerable amount of earthy impurity, consists chiefly of vegetable 
 matter, or, in other words, carbon is its prevailing ingredient. Where 
 the earthy or mineral ingredient greatly exceeds the organic, it become's 
 unfitted for combustion, and is regarded merely as a carbonaceous stone, 
 
THEIR ECONOMIC IMPORTANCE. 155 
 
 Besides these varieties, founded chiefly on mineral charac- 
 ters, it is also customary to distinguish coals according to 
 the purposes for which they seem best suited, or to which 
 they are most frequently applied; hence we hear of household 
 coals, furnace coals, smithy coals, steam coals, gas coals, oil 
 coals, and similar distinctions. 
 
 We have thus occurring in the crust of the earth not 
 only a great variety of coaly substances, but also coals of 
 different aspects and qualities occurring in the same geolo- 
 gical formation. The causes of these differences are, in 
 general, sufficiently obvious : age, and the amount of chemi- 
 cal change to which they have been subjected ; the amount 
 of earthy impurities commingled with them during their 
 aggregation and deposition ; the nature of the plants com- 
 posing the bulk of the mass ; the amount of decay which 
 the vegetable mass had undergone before it was finally 
 covered by other strata; and the porous or retentive nature 
 of the strata between which it is imbedded. All these and 
 other causes have tended to create the differences that now 
 exist among the different members of the Coal Family the 
 
 of which clay, sand, and the like form the main proportion. The term 
 shade, on the other hand, refers to structure rather than to composition, 
 and is something that splits up or peels off in thin layers or laminae. Most 
 consolidated muds are characterised hy this quality of splitting or break- 
 ing up in thin leafy layers parallel to their bedding ; hence shales may be 
 regarded as consolidated muds, and may be distinguished as calcareous, 
 arenaceous, or bituminous according to their predominating ingredient. 
 Bituminous shales, therefore, have been mere vegetable muds their rich- 
 ness, like those of the coals, depending upon the amount of organic matter 
 and the conditions under which it was preserved. Some shales may be as 
 bituminous as some poor varieties of coal, but this does not entitle them 
 to be ranked as coals, any more than an excess of earthy matter in a hard 
 stony coal would entitle it to be called a shale. The terms refer to struc- 
 ture rather than to composition ; and though it is true that the shaly or 
 leafy structure is almost invariably characteristic of the earthier ingre- 
 dient, yet it must ever be borne in mind that both shales and coals are 
 mixed rocks, and that not unfrequently the one may pass into the other 
 by insensible gradations. 
 
156 COAL AND COAL-FORMATIONS. 
 
 graphites and anthracites burning like charcoal, without 
 smoke or flame; the ordinary bituminous coals burning with 
 varying degrees of smoke and flame j the lignites burning 
 with stifling odour, and expelling much watery vapour and 
 smoke ; and the peats scarcely combustible till dried in the 
 sun or by hydraulic pressure, and then burning with little 
 flame but with much smoke and their own peculiar odour. 
 But whatever their peculiarities in these respects, they are 
 all highly important substances, and stand along with iron 
 as the most valuable that human industry obtains from the 
 crust of the earth. Indeed, the coals are altogether indis- 
 pensable to modern civilisation, the peculiar mechanical 
 phases of which are mainly of their own creating. So long 
 as man depends upon the forests for his fuel, his mastery 
 over the metals is limited, and his mechanical appliances 
 restricted. But when he has once learned the uses of coal, 
 and can obtain it in fair supplies, his metal-working powers 
 expand, and his forges, factories, steam-engines, steam- 
 ships, gas-works, railroads, and electric telegraphs become 
 the necessary developments of this new acquirement. Once 
 acquainted with these and similar appliances, man takes his 
 stand on a higher platform, gains new ascendancy over the 
 forces of nature, and overcomes in a great measure the ob- 
 stacles which time and space oppose to his operations. 
 
 Where and at what time man first began to employ coal 
 as a fuel is unknown. The Chinese and Japanese have 
 evidently been long acquainted with its uses, but their 
 chronology is uncertain. The Hindoos, Egyptians, and 
 other Oriental nations never seem to have searched for 
 any variety of mineral coal, but laboriously prepared wood- 
 charcoal for their metallurgical processes. The Greeks and 
 Komans were acquainted with its properties, though they 
 appear to have seldom employed it, and this on the most 
 
THEIR ECONOMIC IMPORTANCE. 157 
 
 limited scale.* In our own country some ancient crop- 
 workings, with stone hammers and hatchets still remaining, 
 date back perhaps to the Roman invasion, and " coal" is 
 mentioned in Saxon records of the ninth century; "but it 
 was not till the twelfth and thirteenth centuries that the 
 value of the substance began to be fairly recognised. And 
 in connection with these facts it is a circumstance worth 
 noting, that no savage race has ever yet been discovered 
 that seemed to be aware of its nature and uses. It may 
 crop out along the ravines and sea-cliffs, as it does in 
 North America, in Eastern Africa, in Farther India, in 
 Australia and New Zealand, but the savage never bends 
 to dig while the twigs and branches around him can be 
 broken. The use of certain minerals and metals are, in 
 truth, as satisfactory tests of man's progress in civilisation 
 as the cultivation of certain plants or the domestication of 
 certain animals. The possession of the one may largely in- 
 crease his comforts ; a knowledge of the other invests him 
 with new and higher powers. 
 
 As a nation we cannot exalt too highly the importance of 
 our coals and coal-fields. Our mechanical, manufacturing, 
 and commercial greatness is intimately bound up with their 
 existence ; and whatever tends to disseminate a knowledge 
 of their nature, to develop their resources, or economise 
 their products, is worthy of our encouragement and atten- 
 tion. Commercially, we may have no immediate interest 
 
 * It is thus referred to by Theophrastus, a Greek author, who wrote 
 about 240 years B.C. : " Those fossile substances that are called Coals, 
 and are broken for use, are earthy ; they kindle, however, and burn 
 like wood coals. These are found in Liguria, where there also is amber, 
 and in Elis in the way to Olympias over the mountains. These are used 
 by the smiths. " Sir John Hill's Translation, 1774. The Ligurian coal 
 would appear, from its connection with amber, to have been lignitic; 
 the Olympian coal, now being worked by a modern company, is bitumin- 
 ous and of older date. 
 
158 COAL AND COAL-FORMATIONS. 
 
 in the substances called coals , but indirectly every man is 
 less or more indebted to their applications ; and it must be 
 a dull or indifferent mind that cannot be induced to take 
 some interest in products to which his country owes so 
 much of her power and greatness, and himself so many of 
 the comforts and amenities he is daily enjoying. 
 
THE OLD COAL-MEASUEES. 
 
 THE CARBONIFEROUS OR COAL SYSTEM ITS PLACE IN GEOLOGY 
 NATURE AND COMPOSITION OF ITS STRATA ITS UPPER, MIDDLE, 
 AND LOWER DIVISIONS VARIETIES OF ITS COALS APPARENT 
 CAUSES OF IGNEOUS ROCKS ASSOCIATED WITH ITS STRATA ITS 
 FOSSIL FLORA AND FAUNA EXUBERANCE OF ITS PLANT-LIFE 
 GENERAL GEOGRAPHICAL CONDITIONS OF THE PERIOD THE COAL- 
 MEASURES AS AN ECONOMIC REPOSITORY VARIETY AND VALUE OF 
 ITS PRODUCTS THEIR INFLUENCE ON HUMAN CIVILISATION AND 
 PROGRESS EXTENT AND DURATION OF PALEOZOIC COAL-FIELDS. 
 
 THE reader who has perused the preceding sketch, will have 
 seen that coal is a product of every geological epoch, from 
 the peat now accumulating on the earth's surface down 
 through the lignites of the tertiary, the true coals of the 
 secondary, and the harder coals and anthracites of the pri- 
 mary periods. But though thus occurring in all stages of 
 the earth's history, it is in the so-called " Carboniferous Sys- 
 tem " that it appears in numerous seams, in many varieties, 
 and in great thickness and continuity over extensive areas. 
 It is from this old system that Britain, France, Belgium, 
 Eussia, China, Australia, and the United States of Ame- 
 rica obtain their main supplies ; hence the familiar terms 
 " Coal-Eormation " and " Coal-Measures," as if it were the 
 only series of coal-yielding strata in the crust of the globe. 
 In Britain it generally rests on a series of reddish sand- 
 stones, and is in turn overlaid by another series of red 
 sandstones ; the former being naturally designated the 
 
160 THE OLD COAL-MEASUKES. 
 
 " Old Eed/ J and the latter the " New Eed," by the sys- 
 tematic geologist. It thus holds a sort of middle place in 
 chronological classification, being younger than the Cam- 
 brian, Silurian, and Old Red systems, and older by far 
 than the Chalks, Oolites, and New Eed Sandstones. Its 
 position is well defined, and may be seen at a glance in the 
 following sequential arrangement : 
 
 CAINOZOIC , ( Quaternary or Recent. 
 (Recent). \ Tertiary. 
 
 ( Cretaceous or Chalk. 
 flf^/T 1 Oolitic or Jurassic. 
 
 t Triassic-(Upper New Eed). 
 
 {Permian (Lower New Eed). 
 CARBONIFEROUS THE OLD COAL-MEASURES. 
 Old Eed Sandstone and Devonian. 
 Silurian. 
 
 Eozoic ( Cambrian. 
 
 (Dawn.) \ Laurentian. 
 
 It is to these paleozoic or ancient coal-measures, in con- 
 tradistinction to all others, that we direct the present 
 sketch, dwelling more especially on their geological aspects, 
 and only incidentally alluding to their industrial applica- 
 tions and importance. We say " incidentally alluding ; " 
 for their building-stones, fire-clays, alum-shales, limestones, 
 ironstones, and coals the labour and skill expended in 
 mining them, the innumerable uses to which they are ap- 
 plied, and their bearings on the industrial and social condi- 
 tions of a people are subjects which of themselves would 
 require the consideration of half-a-dozen sketches. 
 
 Perhaps the most intelligible way of treating any geolo- 
 gical system, is to consider it first as a Eock-formation, 
 second as a Life-period, and third as an Economic reposi- 
 tory. In this way we get an insight into the nature of the 
 strata of which it is composed, and the agencies concerned 
 
'f 1*f 
 
 THEIR COMPOS1TI 
 
 in their aggregation; into the character of its fossils, which 
 thus throw light on the geographical conditions of the 
 period ; and, finally, into its industrial value, as bearing on 
 the wants and progress of civilisation. Adopting this me- 
 thod, we find the Carboniferous system composed in the 
 main of sandstones, shales, fire-clays, ironstones, limestones, 
 and coals, all many times alternating with each other, and 
 in some districts attaining to a thickness of 12,000 or 
 14,000 feet. Of course, during the deposition of such a 
 vast thickness of strata, and which necessarily implies the 
 lapse of long ages, there must have been frequent changes 
 in the relative levels of sea and land ; and hence some of 
 these sediments were laid down in deep and others in shal- 
 low water, while the shallower beds were once more sunk 
 to greater depths, and overlaid by newer sediments. In 
 this way the Carboniferous system consists, in most regions, 
 of several series of strata, and in the British Islands these 
 are generally arranged and named as follows : 
 
 1. Upper or true coal-measures. 
 
 2. Millstone grit or sandstone series. 
 
 3. Carboniferous or mountain limestone. 
 
 4. Lower coal-measures or carboniferous shales. 
 
 Although these several series have evidently been depo- 
 sited in waters of various depths and under somewhat dif- 
 ferent geographical conditions the lower being apparently 
 more estuarine, the mountain limestone being more marine, 
 the millstone grit more littoral, and the upper more terres- 
 trial still there is a great family resemblance, so to speak, 
 between them, and, with the exception of the coal-seams, 
 they are all strictly sedimentary, and bear in their structure 
 and texture abundant evidence of the aqueous agencies con- 
 cerned in their formation. In the sandstones and grits 
 often ripple-marked, rain-pitted, and worm-burrowed we 
 
 L 
 
162 THE OLD COAL-MEASURES. 
 
 trace the sands of open and exposed shores ;* in the shales 
 and fire-clays and ironstones, the muddy deposits of deeper 
 waters; and in the limestones, which also vary much in 
 composition and character, the shell-beds, the coral-growths, 
 and zoophyte drifts, both of the brackish estuary and of the 
 outer ocean. Of course, among sediments so varied we 
 may expect to find every degree of admixture sandstones 
 pure, quartzose, and compact; sandstones flaggy, laminated, 
 and clayey ; and sandstones calcareous and coaly. Shales 
 so purely argillaceous as to be termed fire-clays, shales cal- 
 careous, shales bituminous, and shales so sandy as to pass 
 into flaggy sandstones. So also it is with the limestones ; 
 some so pure as to contain scarcely a trace of earthy matters, 
 and others so mingled with earthy impurities as to be alto- 
 gether unfit for economical purposes. The ironstones, too, 
 which were merely the ferruginous muds of the Carbonifer- 
 ous sea (chemically aggregated by the union of the carbonic 
 acid given off by decaying vegetation, and the iron held in 
 solution in the waters), appear as " clay-bands" or clay- 
 carbonates, as " black-bands " mingled more or less with 
 coaly matter, or as stony impregnations too poor to be 
 worked to advantage. 
 
 Respecting the coals, which we separate from the strictly 
 sedimentary beds, there are also many varieties both as to 
 composition and structural peculiarity. "Where the vege- 
 table mass has evidently accumulated on the spot, as peat- 
 moss, swamp-growth, and forest-growth, the seam is generally 
 
 * Several of the thick-bedded sandstones of the British coal-fields have 
 evidently arisen, in the first instance, from JMian or wind-blown sands, 
 like those that form the " links " and " dunes " of the present day. 
 Their whole internal arrangement points to this mode of aggregation, 
 though they have, of course, been subsequently submerged and planed 
 down on their upper surfaces by the action of water. Illustrative ex- 
 amples may be seen along the eastern shores of Fife, and especially 
 between Crail and St Andrews. 
 
THEIR COMPOSITION. 163 
 
 pure, and spread over a considerable area, with great regu- 
 larity as to thickness and quality. Surprise has been fre- 
 quently expressed at the uniform thickness which many 
 coal-seams maintain over extensive areas. Growth of the 
 vegetable mass in situ is no doubt the main cause, but we 
 must not lose sight of the fact that, when in a semi-plastic 
 state of bituminisation, the pressure from above would have 
 a tendency to spread out the seam, and insensibly equalise 
 its thickness. On the other hand, where interruption to 
 this growth has taken place either from periodical inun- 
 dations or otherwise, the seam contains layers of earthy 
 matter, and is more or less impregnated throughout with 
 such impurities. Again, where the seam has arisen from 
 drifted vegetation, it is still less regular in thickness, and 
 often so earthy and impure as to pass into a bituminous or 
 coaly shale. These bituminous or coaly shales, now coming 
 so largely into use in the Scottish coal-fields for the distil- 
 lation of paraffin and paraffin oil, are indeed of very vari- 
 ous origin and composition. Some of the richer sorts are 
 merely compressed and mineralised vegetable muds that 
 have arisen from long maceration and decay; others, during 
 this long decay in shallow water, have got so largely mingled 
 with the remains of minute crustaceans (cyprides, &c.), as 
 to be partly of animal origin ; * and some again of the poorer 
 sorts are little else than thick clayey silts, irregularly inter- 
 mingled with vegetable and amimal debris. In this way 
 the various purities of coal can be readily accounted for, 
 while difference of mineral aspect and quality may have 
 arisen partly from the nature of the vegetation, partly from 
 
 * One of the most remarkable we have examined is the " Grey Shale " 
 of West Calder, raised for the extensive paraffin works of Mr Young, 
 and which derives its name from the colour imparted to it by the cal- 
 careous cases of these minute organisms. In some places the seam, 
 which is upwards of two feet thick, is literally a mass of these remains. 
 
 
164 THE OLD COAL-MEASUEES. 
 
 the rapidity with which it was entombed, partly from the 
 porous or retentive character of the imbedding strata, and 
 partly also from the degree of mineralisation the respective 
 seams have undergone. Hence the soft caking coals, which 
 fuse together in burning ; the hard, slaty, splint coals, which 
 burn dry and open ; the coarse cubic coals, which also burn 
 open and leave much earthy ashes; the compact, lustrous, 
 cannel coals, used chiefly in the making of gas, and other 
 varieties well known in one or other of our British coal- 
 fields. There is no great difficulty, we repeat, in account- 
 ing for the varieties of palaeozoic coals, if we only make 
 allowance for difference in the nature of the vegetation, in 
 the modes of its accumulation, the length of time it was 
 exposed to maceration and decay, the retentive character of 
 the covering stratum, and the intensity of mineralisation 
 which these different conditions would induce. Of course, 
 all this implies long ages of growth and decay, repeated 
 emergence and submergence of the land, but in the main a 
 gradual subsidence to permit that vast accumulation of sedi- 
 ments sandstones, shales, ironstones, and limestones, to 
 the thickness of many thousand feet which constitute the 
 bulk of the Carboniferous system. 
 
 Besides the strictly sedimentary strata, the coal-measures 
 are also in some districts largely made up of igneous pro- 
 ducts, which intermingle with them as masses of basalt and 
 greenstone, beds of trap-tuff, and other vulcanic discharges. 
 Of course, these discharges must have taken place in or 
 near the seas of deposit, now as overflows of lava, now as 
 showers of ashes, and again as the mingled products of vol- 
 canic eruption. Just as insular and submarine volcanoes 
 are at the present day mingling their eruptive matters with 
 the sediments of the adjacent seas, so in the old coal period 
 similar agencies were at work, and the results are now the 
 interstratified greenstones and trap-tuffs, the bent and frac- 
 
VULCANISM OP THE PERIOD. 165 
 
 tured strata, and the filling-up of the rents and fissures 
 with igneous rock-matter. "We say " interstratified green- 
 stones," for some observers speak of "intrusive green- 
 stones," as if, during the vulcanic paroxysms, such igneous 
 rocks had been forced for miles in every direction between 
 the separated strata ! There are, no doubt, intrusive masses 
 among the strata of every formation, but these are general- 
 ly limited in extent, irregular in form, and bake or harden 
 alike the immediately underlying and overlying beds. The 
 interstratified greenstones, on the other hand, affect only 
 the strata on which they rest, and to regard such wide- 
 spread lava-like sheets as intrusive, is simply an absurdity. 
 Indeed, almost every feature of the vulcanism of the period 
 has been perfectly preserved to us, and the imagination has 
 little difficulty in recalling the broad bays and estuaries of 
 the Carboniferous ocean, studded with their cones and 
 craters of eruption here ejecting showers of dust and 
 ashes, there discharging floods of molten rock-matter, and 
 ever and again the whole shaken and fractured by earth- 
 quake energy and convulsion. Part of this vulcanism was 
 contemporaneous with the deposition of the sediments, as 
 proved by the interstratified greenstones and trap -tuffs, 
 but part also happened long subsequent to the solidifica- 
 tion of the strata, as seen in the faults and dykes of 
 injected matter that intersect the whole thickness of the 
 system ; but whether contemporaneous or long subsequent, 
 it forms one of the most remarkable features in the coal- 
 formation, engaging the closest study of the geologist, and 
 exercising all the ingenuity of the miner and engineer. 
 If the reader could picture to himself the district in which 
 he resides fractured by earthquake convulsion here a 
 portion thrown many fathoms up, there another portion 
 thrown many fathoms down, and the rents between filled 
 with solidified lava he would have before him precisely 
 
166 THE OLD COAL-MEASURES. 
 
 the appearance presented by the "upthrows and down- 
 throws," the " faults and dykes " of many coal-fields, and 
 especially of those of the Scottish Lowlands. 
 
 Composed, like other systems, partly of stratified sedi- 
 ments, and partly of unstratified masses which were the 
 volcanic products of the period, the Coal-measures present 
 no great difficulty as a Bock- Formation, and few of its 
 strata have undergone much metamorphism or internal 
 change, unless where in contact with igneous eruptions. In 
 its stratified rocks we perceive the obvious sediments of 
 seas, lagoons, and estuaries, the relics of shell-beds and coral- 
 reefs, the vegetable growths that accumulated for centuries 
 in swampy morasses,* flourished in the virgin forests, or 
 tangled rankly in the river-jungle ; and in its unstratified, 
 the eruptive mass, the molten overflow, and the frequent 
 shower of dust and ashes. Interrogated as mere rock- 
 masses, they expand overflow after overflow, and stratum 
 upon stratum, like the leaves of a mighty volume, and tell 
 of gigantic rivers and estuaries, of shallow seas, tides, and 
 ocean-currents, of low-lying continents and volcanic archi- 
 pelagoes, of shell-beds and coral-reefs, of vegetable growth 
 and vegetable drift, of rains that fell, winds that blew, and 
 suns that shone and gladdened the face of nature even as 
 they do now. Of all this, and much more, these coals and 
 sediments bear abundant testimony; and interesting as it 
 must ever be to the educated mind to trace back the unity 
 
 * A curious proof of the morass or swamp-growth of many of our 
 coal-seams, is to be found in the narrow winding " wash-outs " by which 
 they are frequently intersected. These " wash-outs" of the miner are 
 stream -like courses from which the coaly matter has disappeared, its 
 place being taken by stony substances. They have been clearly runnels 
 or water-courses that threaded their way through the swamps, and 
 thereby prevented the accumulation of the vegetable matter, just as at 
 the present day our peat-mosses are cut into channels by the streams 
 that may drain their surfaces. 
 
LIFE OF THE PERIOD. 167 
 
 and continuity of the physical agencies that mould and mo- 
 dify the face of nature, that interest becomes immeasurably 
 enhanced when we associate the results of these old-world 
 operations with the necessities of the present, and trace in 
 them an obvious provision for the social and intellectual 
 advancement of man. 
 
 "We come next to consider the Carboniferous system as a 
 life-period, and though there must necessarily be consider- 
 able differences between the fossils of its respective divi- 
 sions carboniferous shales, mountain limestone, and coal- 
 measures yet in a sketch of this kind the aim is more 
 an outline of the whole than the consideration of specific 
 minutiae, which can only be appreciated by the professed 
 palaeontologist. Perhaps the most remarkable feature of the 
 period is its Flora a flora remarkable not only for its vast 
 exuberance, but for the peculiar character of its plant-forms, 
 which bear, in most instances, but a faint resemblance to 
 those of the present day. This vegetation is for the most 
 part converted into coal, but here and there, scattered 
 throughout the shales and sandstones, we find leaves, fruits, 
 stems, trunks, and roots, which indicate its nature, and 
 from these the botanist must construct the aspects of the 
 carboniferous flora. Sea-weeds, marsh-plants like the equise- 
 tums, reeds, and rushes, a vast variety and exuberance of 
 gigantic ferns and clubmosses, pine-like trees with their 
 leaves and cones, and a still greater number perhaps which 
 cannot be assigned to any existing order, may be said to 
 constitute the bulk of the coal vegetation. Fragmentary, 
 and converted into coaly or stony matter, the botanist has 
 no easy task in reading these old- world forms, and all that 
 he can in many instances do, is to trace a resemblance and 
 give a name founded on some external peculiarity. It is 
 for this reason that we find in lists of carboniferous plants 
 
168 THE OLD COAL-MEASURES. 
 
 such names as catamites (reed-like), equisetites (equisetum- 
 like), lycopodites (clubmoss-like), sphenopteris (wedge-leaf 
 fern), neuropteris (nerve-leaf fern), lepidodendron (scaly- 
 bark tree), bothrodendron (pitted tree), and so forth, all 
 pointing to some obvious feature which distinguishes them 
 one from another, but throwing very little or any light on 
 their true botanical affinities. But whatever their strict 
 affinities, we know that most of them belonged to the lower 
 orders of vegetation the horsetails, ferns, and clubmosses, 
 the grasses, sedges, and rushes, the cycads and pine-trees, 
 or perhaps more properly to extinct forms that stood inter- 
 mediate, as it were, between these various orders. Though 
 lowly in organisation and most of them were undoubtedly 
 so they seem to have occupied large areas of the earth for 
 ages, and to have grown in rank luxuriance, till in numer- 
 ous instances their accumulated masses form seams of coal 
 from a few inches to many feet in thickness. 
 
 When we turn to the Fauna of the period, we find 
 throughout the same variety and the same numerical abun- 
 dance, though, of course, certain forms are more abundant 
 in one portion of the system than in another. These forms, 
 too, are chiefly aquatic fresh- water, estuarine, and marine j 
 there being few terrestrial species yet discovered, and these 
 only at wide intervals and in few localities. Beginning with 
 the lower forms, we have a number of minute foraminiferal 
 organisms, and a vast exuberance of corals and encrinites, 
 so vast that beds of the mountain limestone, hundreds of 
 feet in thickness, are almost entirely made up of their 
 remains. There are also trails, burrows, and tubes, that 
 indicate the existence of marine annelids ; abundance of 
 crustaceans, some minute and bivalved like the cypris, a 
 few species of trilobites, and others like the king-crab, and 
 of large dimensions. The polyzoa or flustra-like organisms 
 occur too in great variety, scattering their netted cells 
 
LIFE OF THE PERIOD. 169 
 
 through the shales and limestones ; and shell-fish of every 
 known order bivalve and univalve, deep-sea and shore 
 dweller occur throughout the entire system, though most 
 abundantly, of course, in the marine beds of the mountain 
 limestone. Fishes of many forms are likewise abundant, 
 especially in the lower series of the system, their shining 
 enamelled scales, predaceous teeth, and defensive fin-spines 
 being scattered through the shales, ironstones, and lime- 
 stones. Many were large and shark-like, their palatal teeth, 
 jaws, scales, and fin-spines indicating lengths from twelve 
 to eighteen and twenty feet, and bulky in proportion. Being 
 chiefly cartilaginous, their bodies have in most instances 
 utterly disappeared, and only their teeth or enamelled fin- 
 spines remain to testify to their existence. We have seen 
 hundreds of teeth and spines from a single layer of black- 
 band ironstone, and yet no other vestige of the fishes to 
 which they belonged, not even a patch of scales in juxta- 
 position, to indicate their affinities. Higher than fishes, 
 reptiles also make their decided appearance, most of them 
 aquatic and fish-like in form, though a few ascend to true 
 lacertilian or terrestrial species. Of the terrestrial fauna of 
 the period we know little ; but the insects, land-snails, and 
 reptiles of arboreal habits, which have been found in cer- 
 tain coal-fields, were surely not the sole inhabitants of the 
 carboniferous islands and continents, and we may safely 
 look forward to the discovery of other and higher forms of 
 which these were the necessary congeners. Even while we 
 write, the announcement of several new genera of reptiles 
 from the coal-field of Kilkenny gives additional encourage- 
 ment to this expectation, and all that seems necessary to 
 its fulfilment is merely more minute research and more 
 careful examination on the part of paleontologists. Indeed, 
 when we consider the difficulty of preserving terrestrial 
 organisms, how much they are subjected to waste and de- 
 
170 THE OLD COAL-MEASURES. 
 
 cay, and how few are necessarily washed down into estuaries 
 and seas of deposit, it is wonderful to learn that such fra- 
 gile remains as those of insects, land-shells, and tree reptiles 
 should have been saved from destruction. And surely, if 
 larger and stronger forms had existed, the hope may be in- 
 dulged that they too have been preserved, and will one 
 day or other be detected. 
 
 Such is a hurried glance at the Life of the old Carbonifer- 
 ous period, and more especially as displayed in the areas of 
 Europe and North America, where mining operations have 
 been most extensively conducted. Whether these extensive 
 coal-fields were all contemporaneous is a subject open to 
 question. Indeed, the probability is that they were not 
 strictly contemporaneous, but merely belonged to a great 
 cycle of the earth's history characterised by these coal- 
 forming conditions, and in the main by the sanies facies of 
 plants and animals. But however this may be decided by 
 future and more exact inquiry, we perceive in the mean 
 time a wonderful similarity all over the old coal-measures, 
 and an exuberance of life that has never been excelled dur- 
 ing any subsequent epoch. To account for this exuberance, 
 especially in the vegetable world, various hypotheses have 
 been advanced, such as a greater proportion of carbonic 
 acid in the atmosphere, the greater amount of heat derived 
 in those earlier times from the interior of the globe, a 
 general lowering of the land-surfaces, and a higher temper- 
 ature over the coal-yielding areas arising from some change 
 (inclination of the earth's axis or otherwise) in the astrono- 
 mical relations of our planet. In the present state of our 
 knowledge and belief in the stability of the earth's planetary 
 relationships such hypotheses are inadmissible, and we are 
 driven to seek for the solution in the then distribution of 
 sea and land, the climate thereby produced, the nature of 
 
THEORIES OF FORMATION. 171 
 
 the vegetation, of which we as yet know too little, and the 
 long continuance over the same areas of the same external 
 conditions. So far as we can judge of the character of the 
 vegetation (alliance to equisetums, clubmosses, tree-ferns, 
 swamp-pines, and the like), it by no means required a tro- 
 pical temperature for their growth and accumulation, but 
 rather a moist, equable, and genial climate, inundated river- 
 plains and morasses, low-lying deltas and sea-swamps and 
 these could be brought about by the terraqueous arrange- 
 ments of the earth's own surface, and without calling in the 
 aid of anything either preternatural or abnormal. We 
 say, " could be brought about by the terraqueous arrange- 
 ments of the earth's own surface," for it is not difficult to 
 conceive such a position of the land-masses as to receive 
 more heat from the sun and more warmth from oceanic cur- 
 rents, and such a lowness also of the terrestrial surfaces as 
 to offer few points of condensation to aqueous vapours, and 
 thus preserve a greater permanent amount of atmospheric 
 moisture. This moisture would act in a twofold manner 
 in promoting luxuriance of vegetable life first, by afford- 
 ing a full and direct supply for their growth ; and, second, 
 in lessening the radiation of heat from the land-surface, and 
 thereby greatly increasing the general temperature.* But 
 whatever the geographical conditions, they must have con- 
 tinued for long ages over the same areas to permit the ac- 
 cumulation of such a thickness of coals and sediments and 
 igneous eruptions as those which constitute the Carbonifer- 
 ous system. And these accumulations imply vast con- 
 tinents from which they were wasted, large rivers for their 
 transport, extensive deltas and sea- swamps for the growth 
 of coal-beds, frequent volcanic eruptions in or near the 
 
 * For evidence of this peculiar effect of atmospheric vapour, see Profes- 
 sor Tyndall's reasonings and experiments in his ' Heat considered as a 
 Mode of Motion.' 
 
172 THE OLD COAL-MEASURES. 
 
 ^ -~v 
 
 *| 
 
 areas of deposit, and over the whole a gradual subsidence 
 to allow the depositions of bed above bed in such regular 
 and continuous arrangement. And while all this went on 
 the march of life was ever onward and upward. Plants 
 unknown in the Silurian and Old Eed Sandstone periods 
 made their appearance ; newer genera and species of corals, 
 shell-fish, Crustacea, and fishes thronged the waters. Rep- 
 tiles, so doubtfully known in the Old Eed, now appeared 
 in considerable variety j insects, frail and fragile as they 
 generally are, were by no means uncommon j and all that 
 is wanting to complete the scheme of life, as now known to 
 us, is the presence of birds and mammals. Whether this 
 absence of birds and mammals arises from their non-ex- 
 istence during the period, or from the imperfection of the 
 geological record, it is impossible to determine j but clearly 
 the flora and fauna are greatly in advance of those of the 
 Old Eed Sandstone, and all this is in perfect harmony with 
 the geological doctrine of a progressive development of 
 vitality. 
 
 As an economic repository the old coal-measures present 
 a wide field for inquiry and description. The variety and 
 value of their products, the skill and capital expended in 
 obtaining them, and their obvious bearings on the indus- 
 trial and social relations of a nation, are subjects, however, 
 that lie far beyond the scope of a single sketch, and all that 
 we can attempt is little more than a mere enumeration of 
 the principal substances. We allude, of course, more espe- 
 cially to the Coal Formation of the British Islands, from 
 which it may be safely asserted that we derive products of 
 greater value than from all the other formations put to- 
 gether. From its sandstones we obtain many of our most 
 durable and beautiful building-stones ; we fabricate its fire- 
 clays into furnace-bricks, retorts, drainage-pipes, baths, and 
 
THEIR ECONOMIC IMPORTANCE. 173 
 
 other articles of utility and ornament : from its shales we 
 extract alum, copperas, sulphur, and paraffin oils ; its lime- 
 stones are employed in architecture, agriculture, iron-smelt- 
 ing, bleaching, tanning, and numerous other arts, at the 
 same time that they furnish many of our most decorative 
 marbles, and are often the repositories of lead, zinc, anti- 
 mony, and silver : from its ironstones we extract much of 
 that metal without which all our implements would have 
 been comparatively rude and inefficient, and the machinery 
 of our factories, our steamboats, our railroads, and telegraphs 
 impossible ; while with its various coals we heat our dwell- 
 ings, cook our food, light our streets and apartments, and 
 raise that steam-power by which human industry is increased 
 ten-thousand-fold, time and space abridged, and the differ- 
 ent nationalities of the earth brought into more intimate 
 union and brotherhood. 
 
 And yet, important as these substances are, they are far 
 from having attained their limit either in the amounts an- 
 nually raised or in the purposes to which they can be 
 applied. One has only to cast his eye back on the state of 
 our coal-fields some thirty or forty years ago, as compared 
 with what they are now, to be at once convinced of the 
 progress that has been made, as well as of the progress that 
 is still attainable. At that time, fire-clay was raised only 
 from a few open workings, and had little or no value; 
 alum-shale was mined only at a single work; blackband 
 ironstone was rejected; bituminous shales were utterly 
 worthless ; the ordinary coals had for the most part merely 
 a local sale (for there were no railroads), and brought less 
 than half their present prices ; cannel coal was seldom 
 raised, and was scarcely saleable even at a fifth of its pre- 
 sent cost (for gas-works had not then come into operation) ; 
 and the whole amount of coal raised in Great Britain did 
 not much exceed 30,000,000 tons, while now it has reached 
 
174 THE OLD COAL-MEASURES. 
 
 the enormous amount of 100,000,000, and is still steadily 
 increasing ! At that time steam-power had not come into 
 general use at our collieries, and horses, men, "boys, and 
 women toiled indiscriminately under ground and above 
 ground. Shallow workings, open inclines, and stair pits 
 were then the order of the day, with little profit to the 
 employer, and a world of discomfort to the employed. 
 Now our coal-works, though still demanding improvement, 
 are models of systematic engineering in comparison, and 
 are year after year conducted on a more enlarged scale and 
 on more strictly scientific principles, at the same time that 
 they have been placed under a humane and generous system 
 of official surveillance. 
 
 Looking, we say, at the progress that has been made 
 during the last thirty years, at the increasing demand and 
 pressure upon our coal-supplies, and at the general improve- 
 ment in mechanical appliances that is incessantly taking 
 place, we may rely on increased national interest in all that 
 relates to our coal-fields, to new inventions for lessening 
 the toil and danger incident upon mining, and to a still 
 further utilisation of the substances that belong to the 
 Carboniferous system, and which are now only partially 
 employed or altogether neglected. But while we look 
 hopefully forward to this utilisation, we cannot lose sight 
 of the fact that our coal-fields we mean the British coal- 
 fields have a limited area, and that at the present rate of 
 consumption a time must come when every available seam 
 will be exhausted. How far distant this time may be our 
 best practical authorities are by no means agreed, some 
 restricting it to 300 or 400, some to 600, and others again 
 to 1000 years.* It is true that by more economical methods 
 
 * Those interested in the probable duration of our coal-supplies may 
 consult Hull's ' Coal-fields of Great Britain/ the most compendious, as 
 well as the most readable, work on the subject to which we can refer them. 
 
THEIR ECONOMIC IMPORTANCE. 175 
 
 of consumption the present increasing demand will be 
 somewhat restrained ; that with improved methods of work- 
 ing much of the mineral now left underground will "be 
 raised ; and that with more skilful engineering deeper 
 shafts may he sunk through the overlying secondary rocks. 
 But even with all these appliances no man of intelligence 
 can shut his eyes to the facts that we are rapidly working 
 out our best and most accessible coal-seams, that deeper 
 winnings must entail greater expense, and that in less than 
 a century hence the price of British fuel will be immensely 
 increased. How long the supply may be sufficient to sus- 
 tain the supremacy of British industry it is impossible at 
 present to determine, but assuredly two or three hundred 
 years hence all the more accessible portions of our coal- 
 fields will be thoroughly exhausted, and our successors will 
 be driven either to foreign fields, to other sources of heat 
 than coal, or to other centres of industry. No doubt the 
 vast fields of America and Australia are scarcely broken in 
 upon,* and science is every year discovering newer fields in 
 other regions, and this will tend greatly to lessen the pres- 
 sure on those of Great Britain ; but still the results must 
 ultimately be a change in our commercial relations and a 
 shifting of the theatres of manufacturing industry. Under 
 a wide and cosmical view, however, such changes are in- 
 evitable, and we need no more disquiet ourselves about the 
 future condition of our country than about the future dis- 
 tributions of the seas and continents. The rise and decline 
 of nationalities and the phases of their commercial power 
 
 * The available coal areas of Great Britain are usually estimated at 
 little more than 5000 square miles ; those of North America alone 
 exceed 200,000 ! When we add to this the unknown areas of South 
 America, of Australia, of Japan, China, and India, to say nothing of the 
 partially explored fields of Russia and Austria, the reader will readily 
 perceive how immense the stores of fossil fuel laid up for the future 
 requirements of human industry. 
 
176 THE OLD COAL-MEASURES. 
 
 are as clearly under a higher law of progression as are the 
 physical and vital appointments of the globe itself, and 
 to the philosophical conception all great mutations are 
 merely successive stages towards the broader and higher 
 attainment. 
 
 But be this as it may, to our country these Old Coal- 
 Measures have been invaluable : they are the mainspring 
 of her mechanical power and the stay of her commercial 
 greatness, and everything that tends to economise their use 
 or prevent their unnecessary consumption should be hailed 
 as a national advantage. By their aid mankind has gained 
 new triumphs over the powers of nature, and modern 
 civilisation been infinitely accelerated. One cannot, in- 
 deed, reflect for a moment on the utilities of this single 
 formation, without discerning how intimately the most 
 recent period in geology is connected with the most remote, 
 and how all are inseparably woven into one beautiful and 
 harmonious world-plan. Strange, that the mere physical 
 operations of the earth's remotest ages should be so inti- 
 mately associated with the industrial and intellectual opera- 
 tions of the present ! Inexplicable, if creation were not 
 the unfolding of a great moral as well as of a great physical 
 scheme a scheme in which every element and operation 
 in time past as in time present plays an essential part, and 
 from which not a jot or tittle could be abstracted without 
 marring the symmetry and perfection of the whole. 
 
WHAT WE OWE TO OUE COAL-FIELDS. 
 
 BRITAIN'S SUPREMACY IN MECHANICAL AND MANUFACTURING IN- 
 DUSTRY DEPENDENT ON HER COAL-FIELDS PHASES OF MODERN 
 AS COMPARED WITH THOSE OF ANCIENT CIVILISATIONS DIF- 
 FERENCES ARISING CHIEFLY FROM THE USE OF COAL AND 
 IRON SPECIAL PRODUCTS OF OUR COAL-FIELDSCOAL AND ITS 
 VARIETIES IRON AND THE AGE OF IRON LIMESTONES AND 
 MARBLES SANDSTONES AND THEIR RELATIONS TO ARCHITEC- 
 TURE FIRE-CLAY AND FIRE-CLAY FABRICS SHALES, AND THE 
 EXTRACTION OF ALUM, COPPERAS, PARAFFIN, AND PARAFFIN OILS 
 ORES OF LEAD, ZINC, AND SILVER RELATIONS OF MECHANICAL 
 AND MANUFACTURING INDUSTRY TO COAL AND IRON RELATIONS OF 
 INDUSTRY AND COMMERCE TO CIVILISATION AND REFINEMENT. 
 
 EVERY man of thought must be more or less impressed 
 with the conviction that much of Britain's supremacy in 
 mechanical and manufacturing industry has arisen from her 
 rich and readily-accessible coal-fields. A high degree of 
 civilisation, as the histories of ancient nationalities demon- 
 strate, may be attained without the possession of coal- 
 fields ; but the peculiar phases of civilisation, in all that 
 relates to mechanical appliances, manufactures, locomotion, 
 and intercommunication, are the direct results of coal and 
 iron. The fine arts, literature, philosophy, social refine- 
 ment, and political institutions have existed, and may yet 
 exist, where coal-fields are unknown ; but that machine- 
 power^ if we may so express it, which coal and iron put 
 into the hands of man to subdue the forces of nature, and 
 thereby promote the wider advancement of his race, intel- 
 
178 WHAT WE OWE TO OUE COAL-FIELDS. 
 
 lectually as well as materially, is a thing dependent alone 
 upon the existence of a Coal-formation. There is no arti- 
 ficial source of heat (and heat is the spirit of all force) so 
 compact, so portable, so safe, and so readily available as 
 coal ; no substance so adaptive, so strong, and so enduring 
 as iron. There is no artificial power so titanic, and withal 
 so submissive and tractable, as a few pounds of ignited 
 coal acting through the medium of water; no harness 
 save one of iron sufficiently strong to yoke that giant power 
 in the services of human industry. These two substances, 
 coal and iron, have been the main factors in all recent pro- 
 gress ; and that which most broadly distinguishes the 
 Britain of the present from the Britain of the preceding 
 centuries is the extended and extending use of these sub- 
 stances through the instrumentality of the steam-engine. 
 -NTor is it for these two minerals alone that we are indebted 
 to the Carboniferous system ; for from the same formation 
 we obtain numerous other products, all useful in the arts, 
 and some of them indispensable auxiliaries to the employ- 
 ment of coal and iron. These are the sandstones, lime- 
 stones, marbles, fire-clays, oil-shales, alum-shales, and cop- 
 peras-shales, and not unfrequently in some localities the 
 ores of lead, zinc, and silver. 
 
 Taking COAL as the chief product, we find it in many 
 varieties and in all degrees of purity: Caking coal, like 
 that of Newcastle, which is tender and bituminous, and 
 cakes together in burning ; cubic or rough coal, which is 
 harder, burns open, and leaves much ashy residue \ splint 
 or slate coal, like that of Fife, which is hard and laminated, 
 and burns open, with the emission of great heat ; and 
 cannel or parrot coal, compact and jet-like in texture, rich 
 in bitumen, and now chiefly used in our gas-works. One 
 or other of these varieties is found in every coal-field, and 
 according to its quality (for, like all mixed rocks, coal is 
 
COAL. 179 
 
 very variable in quality) is fitted for some special pur- 
 pose domestic fuel, steam-raising, gas-making, oil-making, 
 or metallurgy. For these and kindred purposes about 
 100,000,000 tons are now annually raised from British, 
 coal-fields ; and when we reflect on the necessity for fuel 
 in our northern climate, on the advantages of a cheap and 
 convenient light like gas, on the importance of our manu- 
 facturing machinery which is moved by steam-power, and 
 on the impulse which steam has given to our intercommu- 
 nication by land and sea, it is impossible to over-estimate 
 the importance of this single mineral In young and 
 newly-settled countries the forests may supply its place; 
 but as population increases, as the land must be cleared for 
 grain crops, and as the forest-growth necessarily disappears, 
 coal is yet the only available source of heat, and happy 
 the nation that possesses it in accessible abundance ! To 
 Britain it is all-important ; and when we consider the 
 amount of capital, skill, and industry employed in procuring 
 it, the myriad economical purposes to which it is applied, 
 the facility with which it can be carried, and the safety 
 and readiness with which it can be used, we may well 
 wonder what would have been the condition of our country 
 without it. This, then, we owe to our Coal-fields ; and 
 considering the enormous amount raised from so small an 
 area, the rapidly increasing demand, and the undoubted 
 limits of the supply, everything that tends to facilitate its 
 full and careful extraction or economise its use should be 
 hailed as a boon of no common importance. 
 
 We have alluded to the enormous amount of coal raised 
 from so small an area, and the aggregate of the coal-fields of 
 Britain, though large in comparison with what is possessed 
 by other European countries, does not greatly exceed 5000 
 square miles. Even in this area much of the coal is of inferior 
 quality, much is also unworkable, and a considerable amount 
 
180 WHAT WE OWE TO OUR COAL-FIELDS. 
 
 must always be left in the process of extraction. Under 
 these circumstances, and with a consumption that has 
 trebled itself within the last thirty years, it is not to be 
 wondered that some uneasiness has "Been felt as to the du- 
 ration of our coal supply, and a Royal Commission been 
 appointed (1866) to inquire into the probable amount that 
 still lies un worked, and which seems to be fairly accessible. 
 "Whatever be the issue of the inquiry, two things are certain 
 first, that the supply is limited, and that at the present 
 rate of consumption it will be wholly exhausted in a few 
 hundred years; and, second, should the coal-measures be 
 found to extend under the newer formations, it would be im- 
 possible, with our present appliances, to extract the mineral 
 at these enormous depths, and even if engineering skill were 
 enabled to surmount the difficulty, the increased cost would 
 be tantamount, in all ordinary cases of consumption, to 
 closing the supply. In the mean time, and without dwell- 
 ing on this most unwelcome prospect, our duty is clearly 
 to encourage every plan for the fuller and more careful ex- 
 traction of the mineral, and to do what we can, individually 
 and nationally, to economise the consumption. 
 
 Regarding IRON as the product of next importance, it 
 may be said to occur in two varieties in our coal-fields 
 namely, as a rough clay-carbonate in bands and nodules, 
 and as a finer clay-carbonate in beds of varying thickness, 
 and mingled less or more with coaly or bituminous matter. 
 The former constitutes the " clay-band " of the miner, and 
 the latter the " black-band " the former being the more 
 abundant, the latter the more valuable as containing enough 
 of coaly matter for its calcination without the addition of 
 extraneous fuel. There are other and more abundant sources 
 of iron than the coal-formation (the haematites and siderites) ; 
 but, considering that these ores cannot be reduced to the 
 metallic state without the addition of fuel, the conjunction 
 
IRON AND LIMESTONE. 181 
 
 of ironstone and coal in the same formation in the same 
 mine, we may say renders these clay-hands and hlack-hands 
 of peculiar importance. Ahout 5,000,000 tons of pig or 
 cast iron are annually manufactured in Britain, and of this 
 the greater proportion is obtained from our coal-fields. 
 Looking at the peculiar phases of modern civilisation, it is 
 impossible to over-estimate the importance of an abundant 
 supply of iron. Indeed, without this abundance, our varied 
 machinery, our steam-engines, our railroads, gas and water 
 pipes, suspension bridges, iron ships, and other similar in- 
 ventions, would have been impossible, or if possible, would 
 have been on a limited and insignificant scale in comparison. 
 This work and application of iron is one of the leading 
 features of our times its malleability, strength, durability, 
 and cheapness fitting it for almost every purpose, from the 
 homeliest utensil of domestic use to the most elegant and 
 complicated machinery, and from the tiniest implement of 
 art to the most gigantic instrument of war. Ours is in 
 truth the Age of Iron, there being no industrial operation 
 in which that metal does not play an important part, no 
 enduring subjugation of the forces of nature unless through 
 its instrumentality and power. 
 
 Besides coal and iron, LIMESTONE also takes rank as one 
 of the abundant and valuable products of our coal-fields. 
 Associated with coal and ironstone, it becomes of especial 
 value as a flux for the reduction of the latter in the blast- 
 furnace, and all the more valuable that it is obtained from 
 the same formation, and generally in convenient proximity. 
 It is also extensively used for mortar and cements, in agri- 
 culture, in tanning, bleaching, and other industrial processes, 
 and not unfrequently some varieties are hard enough and 
 beautiful enough in texture to be raised and polished as 
 marbles. Taken together, there are no mineral substances 
 so valuable as coal, ironstone, and limestone ; and it seems 
 
182 WHAT WE OWE TO OUR COAL-FIELDS. 
 
 something more than, a mere coincidence that in the coal- 
 formation they should have been associated in such close 
 proximity and accessible abundance. Had there been no 
 other rocks in the carboniferous series save these three, the 
 gifts of our coal-fields would have been incalculable; how 
 much more their value when other products, all useful and 
 abundant, can be raised from the same system, from the 
 same shaft, and in course of the same mining operations ! 
 
 SANDSTONES of great beauty and durability, like those 
 of Edinburgh, St Andrews, Stirling, Glasgow, Newcastle, 
 Leeds, and other localities, are obtained in inexhaustible 
 supplies from the Coal-formation; and when the importance 
 of substantial and elegant edifices is duly considered, these 
 building-stones must be ranked among the more valuable 
 of its products. Taking Edinburgh, Glasgow, and New- 
 castle as examples, the fitness, beauty, and durability of the 
 coal -measure sandstones for architectural purposes must 
 stand unquestioned; and, considering the readiness with 
 which they can now be carried by railway to all parts of 
 the island, the rapid extension of their employment may be 
 safely predicted. Nor is it merely for building purposes 
 that these sandstones are used, but many of their varieties, 
 as their names imply (millstone grit, grindstone grit, &c.), 
 are extensively raised for millstones, grindstones, whetstones, 
 and other kindred purposes. In a rigorous and irregular 
 climate like that of Britain, the possession of a durable 
 building-stone is of prime importance, alike on the ground 
 of comfort and economy, and luckily the coal-formation in 
 one or other of its series affords a cheap and inexhaustible 
 supply. It was the boast of Nero that he found Borne 
 built of bricks, but had left her of marble ; had her seven 
 hills contained such sandstones as those of Craigleith and 
 Binny, the boast might have taken a different direction. 
 Our own Houses of Parliament, whose decay so soon after 
 
 
SANDSTONES AND FIRE-CLAYS. 183 
 
 their erection has excited so much comment, are built of 
 magnesian limestone; had the sandstones of Fife or Mid- 
 Lothian been adopted, as was at one time proposed, the 
 chisel-marks of the builder would have remained unoblite- 
 rated for centuries. 
 
 Next to the sandstones or freestones of the Coal-measures 
 we may place the FIRE-CLAYS, or those argillaceous beds which, 
 from the peculiarity of their composition, may be baked into 
 fabrics of any shape, and of unsurpassed resistance to the 
 effects of either fire or water. These clays, at one time 
 little sought after, have now become of vast importance, 
 and are largely used as substitutes for stone and iron. 
 Plastic, and capable of being fashioned into any form, they 
 are extensively used for fire-grates, furnace-linings, retorts, 
 sewage - pipes, floorings, architectural mouldings, garden 
 ornaments, and a thousand other purposes affording 
 objects of beauty as well as of utility, and, when properly 
 manufactured, of unconquerable durability. Few manu- 
 factures have come of late years so largely into use as 
 fire-clay fabrics \ and, considering their recent introduction, 
 we may confidently look forward, not only to their rapid 
 extension, but to a skill in manipulation which will rival 
 the finest productions of the potter and sculptor. But, 
 altogether apart from works of art, the use of fire-clay 
 fabrics in furnaces, and above all in the cheap and effi- 
 cient drainage of our towns, has been a boon of no common 
 value, as tending at once to the health, the comfort, and 
 amenity of our densely congregated populations. Of course, 
 as the manufacture of fire-clays is intimately dependent on 
 a cheap supply of fuel, the relation of coal and fire-clay in 
 the same field, and often in the same mine, is a thing that 
 must strike the attention of the least reflecting. 
 
 Even the most worthless -looking beds in the forma- 
 tion the SHALES, or consolidated muds are now rapidly 
 
184 WHAT WE OWE TO OUR COAL-FIELDS. 
 
 rising in economic importance. Those yielding alum and 
 copperas (the alum and pyritous shales of the miner) have 
 long been worked, though on a small scale, but now the 
 bituminous shales, or those yielding paraffin and paraffin oil, 
 are eagerly sought after and worked on a gigantic and rapidly 
 extending scale. Fields in the lower Coal-measures of Scot- 
 land, which half-a-dozen years ago did not bring a farthing 
 to their proprietors, are now yielding thousands ; and the 
 distillation of these shales may already be regarded as an 
 established branch of our national industry. ISTor is it 
 merely as sources of a new and brilliant light that these 
 shales acquire their importance. Recent experiments have 
 proved the adaptability of their crude oils as a fuel for 
 steam-raising, and the hope is now held out that even the 
 inferior varieties may be turned to good account in lessen- 
 ing the pressure upon our more precious coal-seams. In- 
 deed, when we consider the worthless aspect of these 
 shales and the beauty and utility of the substances solid 
 paraffin, paraffin oil, naphtha, rosine and magenta dyes 
 derived from them, few instances of human ingenuity to 
 utilise the products of nature could be adduced, at once so 
 marvellous and so thoroughly successful. What so unlike 
 as a block of black bituminous mudstone and a paraffin 
 candle, white and translucent as the finest wax 1 ? What 
 so seemingly impossible as the extraction of a brilliant 
 rose-purple dye from a mass of pitch-coloured coal-tar 1 
 
 Besides these rocks the coals, ironstones, limestones, 
 sandstones, fire-clays, and shales of which the Carbon- 
 iferous system is entirely composed, there occur in some 
 localities independent veins of lead -ores and zinc -ores 
 traversing the beds of the mountain limestone. These 
 veins (like those r of Derbyshire, Yorkshire, and Northum- 
 berland) are often of great commercial value, not only for 
 the lead and zinc they directly supply, but for the per- 
 
SHALES AND METALLIFEROUS ORES. 185 
 
 centage of silver which many of them yield the lead-ores 
 being generally less or more argentiferous. 
 
 Such are the products we derive from the Coal-formation, 
 and such the benefits they have conferred and are still con- 
 ferring on our country. Statisticians may set down their 
 amounts in weights and measures and their values in money, 
 but no method of computation can fully convey an idea of 
 the advantages, physical, intellectual, and moral, we enjoy in 
 possessing such productive and accessible coal-fields. Had 
 the coals been in one field, the ironstones in a second, and 
 the limestones and fire-clays in a third, they would have 
 still been prized and sought after ; but when the whole are 
 found in the same field, and often in the same mine, their 
 value is a hundredfold enhanced, and their importance 
 becomes more distinctly appreciable. Nor can it be over- 
 looked that, situated as most of these coal-fields are, in the 
 lower districts of our island, they are peculiarly accessible 
 by water and readily reticulated by railways the Bristol 
 Channel, the Mersey, the Tees, Wear, Tyne, Forth, and 
 Clyde all opening their ports for convenient transport to 
 other and less favoured localities. Nor is it to Britain 
 alone that the advantages of her coal-fields extend the 
 whole world, through her machinery and manufactures, par- 
 ticipates in the boon, and the impetus thereby given to 
 human progress will descend to future ages. Her steam- 
 engines, manufacturing machinery, railroads, water and gas 
 distribution, telegraphs, and steamships are the giant off- 
 spring of her coal-fields ; and wherever the sound of these 
 is heard or their influences felt new activities and industries 
 are awakened, and on industry and commerce are ever founded 
 the surest hopes of civilisation and refinement. Strange, 
 as we have before remarked, that the mere physical opera- 
 tions of the earth's remotest ages should be so intimately 
 
186 WHAT WE OWE TO OUR COAL-FIELDS. 
 
 associated with the industrial and intellectual operations 
 of the present ! Inexplicable, if creation were not the 
 unfolding of a great moral as well as of a great physical 
 scheme a scheme in which every element and operation 
 in time past as in time present plays an essential part, and 
 from which not a jot or tittle could be abstracted without 
 marring the symmetry and perfection of the whole. 
 
THE SECONDARY AGES. 
 
 THE SECONDARY AGES, EMBRACING THE NEW RED SANDSTONE, OOLITE, 
 AND CHALK SYSTEMS THEIR PLACE IN GEOLOGICAL HISTORY 
 COMPOSITION AND SUCCESSION OF THEIR STRATA PHYSICAL CON- 
 DITIONS UNDER WHICH THEY WERE FORMED THEIR FOSSIL FLORA 
 AND FAUNA EXCESS OF CHAMBERED SHELLS EXUBERANCE OF 
 REPTILIAN LIFE CURIOUS PHASE OF BIRD-LIFE THE ARCH- 
 -EOPTERIX LIFE-CONDITIONS OF THE SECONDARY PERIODS- 
 ECONOMIC PRODUCTS OF THE SECONDARY SYSTEMS SECONDARY 
 COAL-FIELDS THEIR GROWING IMPORTANCE. 
 
 the earlier geologists arranged the rocks of the earth's 
 crust into Primary or first-formed, Secondary or second- 
 formed, and Tertiary or third-formed, they made a most 
 important improvement in geological classification; and 
 though a somewhat different meaning is now attached to 
 these terms, they are still retained in the nomenclature of 
 the science as general and convenient designations. Accept- 
 ing PRIMARY merely in the sense of early or ancient, it em- 
 braces all the stratified systems prior to the New Red Sand- 
 stone ; while SECONDARY, on the other hand, refers to the 
 New Eed Sandstone, the Oolite and Chalk. Even this 
 New Red Sandstone, when critically examined, is found to 
 differ widely in its fossils the lower portion containing 
 palaeozoic forms closely related to those of the Coal-measures, 
 while the upper portion is characterised by mesozoic forms, 
 or such as have a closer relationship to those of the Oolite 
 and Chalk. In this way the " New Ked Sandstone " of our 
 
188 THE SECONDARY AGES. 
 
 forefathers has been separated into two distinct systems 
 the " Permian " or Lower New Eed, so called by Sir Eoderick 
 Murchison because typically displayed in the province of 
 Perm in Eussia ; and the " Triassic " or Upper New Eed, so 
 named by the German geologists because consisting of three 
 well-marked series of strata, the Bunter or variegated sand- 
 stone, the Muschelkalk or shell-limestone, and the Keuper 
 or copper-marls. Adopting this view and it is more by 
 nature of the fossils than by the character of the sediments 
 that the relative antiquity of strata can be satisfactorily 
 determined the secondary ages, which form the subject of 
 the present sketch, comprehend the Triassic, Oolitic, and 
 Chalk systems, whose chronological place will be best under- 
 stood, perhaps, by a glance at the annexed tabulation : 
 
 CAINOZOIC ~i 
 
 or f Quaternary or Eecent Accumulations. 
 
 TERTIARY. /Tertiary. 
 
 MESOZOIC ( Cretaceous or Chalk. 
 
 or < Oolitic or Jurassic. 
 
 SECONDARY. I Triassic or Upper New Ked Sandstone. 
 
 /Permian'or Lower New Red Sandstone. 
 
 I Carboniferous or Coal. 
 
 j Old Eed Sandstone and Devonian. 
 
 ^ Silurian. 
 PRIMARY. Cambrian. 
 
 I Laurentian. 
 
 These secondary systems the Trias, Oolite, and Chalk 
 hold a middle place, as it were, in geological history, less 
 obscure than the primary, but still not so obvious either in 
 their vital or geographical arrangements as the tertiary and 
 recent. The mode in which their strata have been aggre- 
 gated is for the most part apparent, and their fossils, though 
 differing widely in genera and species from existing forms, 
 have still more of a new-world aspect about them, and the 
 palaeontologist feels he has less difficulty in establishing 
 their botanical and zoological relations. Unless in highly 
 
THEIR ROCK-SYSTEMS. 189 
 
 igneous centres, few of the strata have suffered much meta- 
 morphism ; the areas and boundaries of the seas of deposit 
 are much more apparent ; and birds and mammals, unknown 
 in previous systems, are now met with in some abundance. 
 Of course, as the secondary ages embrace several systems 
 and formations, there will necessarily be considerable differ- 
 ence, both in rocks and fossils, between its respective series ; 
 but notwithstanding these differences there is still similarity 
 sufficient to enable us to treat them as a great group, or 
 rather as occupying a continuous and connected portion of 
 the earth's geological history. And after all, it is only by 
 groupings and generalisations of this kind that the non- 
 scientific reader can be expected to catch a glimpse of world- 
 history, the details and reasonings of which must be 
 worked out by the slow and patient research of the profes- 
 sional inquirer. 
 
 The earliest of these Secondary systems, we have said, 
 is the Trias, a series of reddish-coloured sandstones, shelly 
 limestones, and saliferous or salt-yielding marls; the second, 
 the Oolite, a series of calcareous freestones, clays, and 
 shales, with occasional coals and ironstones ; and the third, 
 the Chalk, so notably composed in the south of England of 
 that white, soft, earthy limestone we call "jchalk," and its 
 underlying clays and greensands. With the exception of 
 a subordinate series of strata that lie between the Oolite and 
 Chalk, and known as the " Wealden " from their occurrence 
 in the wolds or woodlands of Kent and Sussex, all the 
 strata of these secondary formations are eminently marine, 
 and are charged throughout with marine organisms. The 
 Wealden sands, sandstones, and clays point more to estua- 
 rine conditions, and where they occur the coals and lignites 
 of the Oolite and Chalk indicate the existence of land-sur- 
 faces; but all the other strata the shelly and coralline lime- 
 
190 
 
 THE SECONDAKY AGES. 
 
 stones and sandstones, the saliferous marls, the shales and 
 clays * replete with the exuviae of shell-fish, Crustacea, and 
 fishes are strictly sea-formed, some littoral or along-shore, 
 and others pelagic or in deeper waters. This marine origin 
 is pre-eminently observable in the Trias and Chalk, and it is 
 only in these oolitic districts where coal and ironstone are 
 found that we have evidence of estuarine and terrestrial 
 conditions of formation. Of course we are here alluding 
 more especially to the secondary systems as displayed in 
 
 * A better idea of the composition of these systems may be obtained, 
 perhaps, by a perusal of the annexed tabulation : 
 
 J Chalky marls and thin-bedded limestones. 
 Chalk rock, with and without imbedded flints. 
 Greensands and cherty limestones. 
 Blue tenacious clays, locally known as " gault " 
 or "golt." 
 Green and ferruginous sands, sandstones, and 
 
 cherty limestones. 
 
 Wealden clays, sands, and flaggy sandstones. 
 Upper Oolite consisting of fine-grained oolitic 
 limestone with interbedded clays and bitumin- 
 ous shales (coals). 
 
 Middle Oolite consisting of coarse-grained shelly 
 and coralline limestone, with blue clays and 
 shelly calcareous grits. 
 
 Lower Oolite consisting of coarse shelly lime- 
 stone and grits ; thick-bedded blue clays (coals) ; 
 thick-bedded sandy oolitic limestone; flaggy 
 grits and marls ; and calcareous freestone. 
 Upper Lias consisting of dark bituminous shales 
 
 and indurated marls or marlstone. 
 Lower Lias dark laminated limestones and clays, 
 bands of ironstone, layers of jet and coal, cal- 
 careous sandstones. 
 
 Keuper consisting of variegated marls, sandy 
 layers, limestone layers, gypsum, and rock- 
 TRIASSIC salt. 
 
 or / Muschelkalk grey shelly limestone, with marl 
 
 UPPER NEW RED. \ partings and beds of magnesian limestone. 
 
 Bunter soft variegated sandstones ; coarse-grained 
 grits and conglomerates. 
 
 OOLITIC 
 
 or 
 JURASSIC. 
 
THEIR ROCK-SYSTEMS. 191 
 
 Western Europe, for it must be observed that in India, 
 Eastern Europe, in Farther Asia, and Southern Africa, as 
 well as in various tracts of North America, the conditions 
 of deposit seem to have been widely different, as there 
 both oolitic and cretaceous coal-fields are by no means 
 uncommon. And these coals, as noticed in a former 
 sketch (Coals and Coal - Formations), must have been 
 formed, like all others, partly from vegetation that grew 
 and accumulated in situ, and partly from drifts and rafts 
 borne down by rivers during seasons of flood and inun- 
 dation. 
 
 There is thus nothing very puzzling in the lithology or 
 mere rock-formations of the secondary ages. In the sand- 
 stones of the Trias studded with footprints and rain- 
 prints, and reticulated with sun-cracks, we see the sandy 
 deposits of shallow shores; in the shelly limestones, the 
 accumulations of somewhat deeper waters; and in the 
 clayey marls, with their masses of rock-salt and gypsum, 
 the muds of lagoons and sea-creeks alternately submerged 
 and cut off from communication with the outer waters. 
 In the limestones and calcareous clays of the Lias and 
 Oolite, we perceive the coral-growths and organic debris of 
 exterior seas ; in their freestones and shell-beds, the drifts 
 of the nearer shore ; while in their coals and jets we dis- 
 cover the growths of sea-swamps and deltas, and the drifts 
 of streams and rivers. Again, in the greensands of the 
 Chalk we trace the operations of the more exposed shores ; 
 while in the Chalk itself we perceive the slowly-accumu- 
 lated calcareous ooze of the quieter waters. For just as in 
 the Atlantic and other sea-beds, the fine calcareous mud 
 resulting from organic debris (the shields of foraminifera, 
 the waste of corals and shells and other exuvise) is now 
 collecting in great thickness and purity over extensive 
 areas, so in the older cretaceous ocean similar agencies were 
 
192 THE SECONDARY AGES. 
 
 at work in accumulating those masses of chalk which now 
 constitute the cliffs and downs of southern England.* 
 There is nothing, we repeat, very difficult of explanation 
 in the mere sediments of the secondary ages, while, as 
 during all other periods, vulcanic eruptions were here and 
 there breaking up their continuity, and occasionally alter- 
 nating with their strata. In England the secondary rocks 
 have suffered little or no disturbance from igneous agency, 
 and hence their broad and unbroken succession in that 
 country. All to the south-east of a line roughly drawn 
 from the Severn to the Tees is occupied by these forma- 
 tions, and the reader has only to cast his eye over the 
 geological map, to 'perceive how regularly and continuously 
 they follow each other. In Scotland and Ireland, however 
 (Skye, Giant's Causeway, &c.), as well as in the Jura and 
 other Continental districts, the secondary rocks are much 
 disturbed and altered by igneous eruptions a proof that 
 during this, as during all other ages, vulcanicity displayed 
 itself only along certain lines and within certain centres 
 with notable intensity. 
 
 As a life-period, the secondary systems, though charac- 
 terised each by its own peculiar forms, have yet so many 
 features in common, that they may conveniently be re- 
 garded as representing one great and unbroken cycle of 
 world-history. As marine deposits they abound in all the 
 lower forms of life foraminifera, sponges, corals, encrinites, 
 star-fishes, sea-urchins, polyzoa, shell- fish, Crustacea, and 
 worms ; contain at the same time many orders of insects ; 
 are replete with numerous families of fishes and reptiles ; 
 and now, for the first time in geological history, give 
 unmistakable evidence of birds and mammalia. Without 
 
 * For more detailed explanation of this deep-sea calcareous ooze or 
 mud, see page 44, in the sketch entitled " Waste and Eeconstruction." 
 
THEIR LIFE-FORMS. 193 
 
 dwelling on minutiae, which would be out of place in a 
 popular sketch like the present, we may yet advert to some 
 of the more remarkable features in the life of the second- 
 ary ages, such as the great preponderance of nautilus and 
 cuttle-fish like forms among the mollusca ; the marvellous 
 variety of reptilian life, which has led to the designation 
 " the age of reptiles ; " the first unmistakable appearance 
 of bird-life ; and the occurrence of mammals of the lower 
 or pouch-bearing section. There are other noticeable fea- 
 tures too, such as the disappearance of the plants peculiar 
 to the coal-measures, and their replacement by other tree- 
 ferns, by cycads, zamias, pine-trees, and palms ; the dis- 
 appearance of the graptolites, trilobites, eurypterites, and 
 bone-encased fishes that characterised the older systems; 
 the prevalence of homocercal or equal-lobed-tailed fishes un- 
 known in paleozoic times, and similar peculiarities; but 
 these we must subordinate to the more remarkable features 
 above alluded to. 
 
 The highest order of molluscan life is the Cephalopod, 
 or those which move about by the arm-like feelers that 
 encircle the head. To this order belong the nautilus and 
 cuttle-fish the former possessing an external chambered 
 shell, and the latter having no external shell, but support- 
 ed by an internal bone or osselet. The nautilus is now the 
 only representative of the shelled division, and though a 
 number of genera belong to the shell-less orders, they do 
 not occur in anything like overwhelming numbers. In the 
 secondary seas, however, these cephalopodous mollusca 
 were predominating forms, their shells and internal bones 
 occurring in myriads, and this more especially during the 
 oolitic and cretaceous periods. Everywhere throughout 
 the limestones, shales, and clays, their remains are scattered 
 in profusion the chambered shells, from the size of the 
 smallest coin to the circumference of a carriage-wheel, and 
 
 N 
 
194 THE SECONDARY AGES. 
 
 the internal bones from the thickness of a quill to the size 
 of a man's arm. There are few things so noticeable in 
 these secondary ages as this exuberance of chambered 
 shells ammonites, baculites, hamites, scaphites, and tur- 
 rilites ; or of these internal bones belemnites, acantho- 
 teuthis, belemnoteuthis, conoteuthis, and leptoteuthis* Many 
 of the strata are surcharged with their remains ; and as the 
 cephalopods are active and predaceous in their habits, the 
 lower life in which they fed must have been still more 
 abundant, while they in turn became the chosen food of 
 the larger fishes and reptiles. Occasionally we hear, as a 
 matter of marvel, of the capture in tropical waters of cuttle- 
 fishes eight or ten feet in length ; how transcendently more 
 wonderful the thronging of these secondary seas with 
 myriads of the same order still more gigantic in size and 
 more diversified in feature ! Strange, too, that the ocean 
 which then swarmed with nautiloid forms should now 
 contain only a single genus ! Inexplicable, were there no 
 plan of vital progression to which these extinctions and 
 creations could be systematically conformed. 
 
 Even still more remarkable was the exuberance of rep- 
 tilian life that thronged the seas, the estuaries, the rivers, 
 and river-plains of the secondary ages. Nothing known 
 before or since of reptile life is at all comparable either in 
 point of variety, size, or numbers. Our museums are re- 
 plete with their remains, and in conditions so perfect, that 
 almost every feature can be restored in natural proportion 
 and life-like reality. Whale -like and confined to the 
 waters, crocodilian -like and amphibious, mammalian -like 
 and treading the land, or bird-like and winging the air 
 
 * Ammonites (coiled up like the horn of Jupiter Ammon) ; bactilites 
 (straight or staff-shaped) ; hamites (hook-shaped) ; scaphites (boat-shaped) ; 
 turrilites (tapering and turret-shaped) ; belemnites (dart-like) ; acantho- 
 teuthis (thorn -like organ); belemno- (bolt -like); cono- (conical); lepto- 
 (elender) ; and so on. 
 
THEIR LIFE-FORMS. 195 
 
 these saurians were undoubtedly the most notable features 
 of the period. It was indeed the " age of reptiles," when 
 every habitat aquatic, terrestrial, and aerial was occupied ; 
 and every function carnivorous, herbivorous, and insec- 
 tivorous was performed by these creatures. Frog-like, but 
 bulky as an ox, the IdbyrintJiodon squatted on the muddy 
 river-flats ; whale-like, the ichthyosaur paddled through the 
 waters ; iguana-like, but huge as an elephant, the iguano- 
 don browsed on the succulent herbage ; bloodthirsty and 
 mightier still, the deinosaur crouched for his prey in the 
 forest ; while bat-like, under the cliffs and adown the river- 
 banks, fluttered the insectivorous pterodactyls* Every 
 place seems to have been usurped and every function per- 
 formed by these abounding reptilian orders; and this for 
 long ages, while bird-life was gradually coming into force, 
 and mammalian life dawning into existence. 
 
 This bird-life makes its first appearance in the Trias, the 
 surfaces of whose flaggy sandstones are thickly imprinted 
 with their footsteps. These ormtkichnites, or bird-foot- 
 prints, occur in all sizes, from the slender impress of feet 
 like those of the snipe and sandpiper to the heavy implant 
 of others many times bulkier than those of the largest 
 ostrich. Waders and runners, they seem to have frequent- 
 ed the sandy shores of creeks and estuaries which were also 
 the favourite haunts of reptiles, and thus many of these 
 Triassic sandstones are crossed and re-crossed, tracked and 
 re-tracked by footprints whose nature (reptilian or ornithic) 
 it is yet impossible to determine. How wonderful the 
 variety and complexity of the vital record ! how strange 
 that the impression of a passing foot should remain as evi- 
 dence of scenes of life and activity when every other relic 
 
 * Labyrinthodon, from the labyrinthine structure of its teeth ; 
 ickthyosaur, fish-like saurian ; iguanodon, having teeth like the existing 
 iguana ; deinosaur, terrible saurian ; pterodactyle, finger- winged or flying 
 reptile. 
 
196 THE SECONDARY AGES. 
 
 has utterly disappeared ! But numerous as "bird-footprints 
 are an d they occur in abundance at Storeton in Cheshire, 
 Corncockle in Dumfriesshire, Cummingstone in Morayshire, 
 Hildburghausen in Germany, and on the Connecticut in 
 A-mp.rica no traces of bird-bones have been detected save 
 in a single instance, and that not altogether free from doubt, 
 in the sandstones of the Connecticut. But what is doubt- 
 ful in the Trias becomes obvious in the Oolite and Chalk, 
 and the comparatively recent discovery of the skeleton of 
 the archceopteryx * (ancient bird) in the lithographic lime- 
 stone of Solenhofen confirms the fact that Bird-Life, whether 
 existing or not in the primary periods, became at all events 
 an established feature in the secondary ages. Yet so it ever 
 appears with the great scheme of vitality ; advancing slowly 
 but incessantly, and displaying at every stage more compli- 
 cated forms and higher functional activities ! 
 
 Conformable to this progress, mammals also make their 
 appearance during the secondary ages scantily in the 
 Trias, but more abundantly and unmistakably in the Oolite 
 and Chalk. As might be expected, and in accordance with 
 a progressional scheme, those mammals belong to the lower 
 or marsupial orders that is, to those which, like the opos- 
 sum and kangaroo, are furnished with a marsupium, or 
 external pouch in which they carry about their immature 
 young. These marsupials or pouch-bearers stand lower in 
 the scale than the true mammals that bring forth their 
 young in a perfect state. They are sometimes termed ovo- 
 
 * This ancient bird, according to Professor Owen, was about the size of 
 a rook, and differs from all known birds in having two free claws belong- 
 ing to the wing, and also in having the vertebrae of the tail (about twenty 
 in number) free and prolonged as in mammals each vertebrae supporting 
 a pair of quill-feathers which give to the tail a long and vane-like appear- 
 ance. This unique specimen (now in the British Museum) exhibits in its 
 tail a retention of structure which is " embryonal and transitory in the 
 modern representatives of the class Aves, and consequently a closer adhe- 
 sion to the general vertebrate type." 
 
THEIR GEOGRAPHICAL CONDITIONS. 197 
 
 viviparous, and, so far as this function of gestation is con- 
 cerned, hold an intermediate place, as it were, between birds 
 and the ordinary mammalia. Numerous teeth and jaws of 
 a small size (about that of a rat or rabbit) have been dis- 
 covered, some indicating herbivorous, some carnivorous, and 
 others insectivorous habits, but all apparently belonging to 
 the same pouch-bearing orders. It is true that in the chalk 
 marls some bones of a doubtfully higher character have been 
 detected, but beyond these fragments nothing higher in the 
 scale of Life than birds and marsupials is known to belong 
 to the secondary ages. 
 
 Here then, during these secondary ages, which embrace a 
 long period of the world's history, we have seas of moderate 
 depth and broad shallow estuaries in which all the ordinary 
 sediments were deposited shelly and coralline limestones 
 in the outer waters, muds and clays in the stiller recesses, 
 and sands on the open shores. Here and there masses of 
 rock-salt and gypsum accumulate in detached lagoons and 
 sea-reaches j while during the oscillations of the land the 
 swamp and forest growths of a genial climate are repeatedly 
 submerged and converted into coal. We say genial climate, 
 for the cycads, zamias, palms, tree-ferns, and broad-leaved 
 pines (which are the prevailing forms), point to warm and 
 equable conditions ; while the frequent oscillations of the 
 land are amply shown in the numerous seams of coal and 
 "dirt-beds" or ancient soils on which the forest-growths 
 had flourished for ages.* And while these genial conditions 
 prevail over sea and land, both are equally exuberant with 
 
 * One of the best known examples of an oolitic soil is the celebrated 
 " dirt-bed " of Portland an earthy, carbonaceous mass, replete with the 
 roots and prostrate trunks of cycads, zamias, and other vegetation charac- 
 teristic of and peculiar to those secondary formations. In fact, a genuine 
 forest-mould, with its rotted leaves, fallen trunks, an mbedded root- 
 stools. 
 
198 THE SECONDARY AGES. 
 
 life the former teeming with foraminifera, sponges, corals, 
 encrinites, starfishes, shell-fish of every order, fishes and rep- 
 tiles ; and the latter with gigantic ferns, reed-like grasses, 
 cycads, zamias, palms, and pine-trees, which "became the 
 chosen food or shelter of numerous insects, of reptiles ter- 
 restrial, arboreal, and aerial, of birds, and of marsupial mam- 
 mals. What a busy panorama of life, growth, and decay is 
 presented by these secondary ages ! And not alone mere 
 growth and decay, but development and progress j for dur- 
 ing the long periods that elapsed between the commence- 
 ment of the Trias and the close of the Chalk, thousands of 
 forms became extinct newer and higher ones taking their 
 places, and at every stage approaching nearer and nearer to 
 those of the Tertiary and Current epochs. So perceptible 
 indeed is this approach that it has been proposed to arrange 
 the geological formations into two great divisions only the 
 palceozoic, embracing all to the close of the Permian ; and 
 the neozoic, all from the commencement of the Trias up to 
 the present day. But whatever may be the value of such 
 arrangements, the fact of progression is everywhere obvious 
 so obvious, that even the non-scientific observer could 
 have little difficulty in distinguishing between the fossil 
 forms of the primary and secondary ages. 
 
 Let those who refuse their assent to a plan of vital devel- 
 opment only study for a day or two the magnificent collec- 
 tion of secondary fossils in our National Museum, or even 
 peruse their figures as given in ordinary geological works ; 
 and if at all capable of comparing, they cannot fail to per- 
 ceive the vast advance that has been made upon the primary 
 or palaeozoic forms. Not only is there the introduction of 
 birds and mammals formerly unknown, but the stamp im- 
 pressed upon all the lower orders corals, molluscs, crus- 
 tacea, fishes, and reptiles is that of greater complexity 
 and specialisation. Let them next compare them with ter- 
 
THEIR ECONOMIC PRODUCTS. 199 
 
 tiary and existing forms, and note in these not only the 
 further introduction of the true timber trees and the higher 
 birds and mammals, but also the still greater degree of 
 specialisation both in form and function which characterises 
 the whole ; and unless blinded by prejudice or incapable of 
 discernment, they cannot refuse assent that there has been 
 a progress, and that this progress has taken place in a way 
 so connected and definite as to lead to the unavoidable 
 conviction of an all-pervading law of development. 
 
 As Economic Repositories the secondary formations are 
 year after year assuming greater importance. Not many 
 years ago, building-stone, limestone, lithographic slabs, 
 fuller's earth, rock-salt, gypsum, and chalk, were the prin- 
 cipal products extracted; but now ironstone like that of 
 Cleveland in Yorkshire, coal from many fields (Austria, 
 India, Indian islands, Brazil, Virginia, Vancouver, and 
 other regions), coprolites or phosphatic nodules for manure, 
 hydraulic cements, and other substances are largely obtained, 
 and as foreign surveys are extended, will in all likelihood 
 be met with in still greater abundance. The geological 
 mapping of the world, by competent authorities, is merely 
 in its infancy; * but as this proceeds the secondary systems 
 are gradully revealing a larger amount of economic treasures, 
 
 * The survey of our own islands, though commenced many years ago, 
 is not half completed ; and those of our colonial possessions Canada, 
 the West Indies, India, Australia, and New Zealand are merely in 
 their first stages. The same may be said of other European countries, 
 most of which have made some progress with their surveys, but still 
 feel the want of more minute and accurate information. The Ameri- 
 can States survey, begun with great ardour, has been finished only in 
 a few instances ; while with the geology of South America, Arctic Ame- 
 rica, Asia, and Africa, we have the slightest and most imperfect ac- 
 quaintance. Till all these areas have been more thoroughly explored, 
 it were presumptuous to dogmatise, and idle to speculate, either as to 
 the scientific aspects or the economic importance of the several stratified 
 systems. 
 
200 THE SECONDABY AGES. 
 
 and exciting an interest more in keeping with that which 
 has so long been attached to their palseontological and 
 purely scientific aspects. In corroboration of this we need 
 only refer to such discoveries as the Cleveland ironstone, 
 which within the last dozen years has wrought such a re- 
 volution on the aspects and industry of northern York- 
 shire ; to the deposits of rock-salt near Middlesborough on 
 the Tees and in Antrim ; and, above all, to the fact that 
 the main coal-fields of India and the East are of secondary 
 origin. How changed the aspect of opinion within the last 
 thirty years, when our predecessors, generalising from their 
 limited knowledge, regarded coal and iron as belonging 
 alone to formations of earlier date, and sought for traces 
 of their existence only in connection with these primary 
 systems ! But so it ever is ; the more limited our acquaint- 
 ance with nature and nature's operation, the more restricted 
 our notions of her bounties, and the less prepared are we to 
 avail ourselves of their benefits and amenities. It is only 
 when mankind have taken the wider survey that they can 
 arrive at sounder conceptions, and forego the conclusions 
 they had drawn from their local and circumscribed expe- 
 rience. 
 
TERTIARY TIMES. 
 
 ORIGIN OF THE TEEM TERTIARY LOWER, MIDDLE, AND UPPER, OR 
 EOCENE, MIOCENE, AND PLIOCENE TERTIARIES THEIR MINERAL 
 COMPOSITION AND SUCCESSION DIFFERENT IN DIFFERENT BASINS 
 OR AREAS OF DEPOSIT FLORA AND FAUNA OF THE RESPECTIVE 
 SUBDIVISIONS PHYSICAL CONDITIONS UNDER WHICH THESE GREW 
 AND WERE DEPOSITED GIGANTIC AND . INTERMEDIATE FORMS OF 
 EOCENE MAMMALS APPROXIMATION TO EXISTING DISTRIBUTIONS 
 IN MIOCENE AND PLIOCENE TIMES ECONOMIC PRODUCTS OF THE 
 SYSTEM. 
 
 WHEN the earlier geologists arranged the stratified rocks of 
 the earth-crust into Primary, Secondary, and Tertiary, they 
 closed the Secondary with the Chalk, and regarded as Ter- 
 tiary all the sediments that occur above that formation. In 
 their estimation Tertiary strata were comparatively limited, 
 and they had no conception of the extent, thickness, and 
 variety of sediments, or of the long periods which this 
 thickness and variety of deposits must necessarily imply. 
 To them primary was equivalent to universal ; secondary- 
 was still very extensive, though not universal ; but the ter- 
 tiaries were mere local patches occupying shallow depres- 
 sions in the older formations. As research went forward, 
 however, modern geologists began to discover that tertiary 
 strata differed widely among themselves both in composi- 
 tion and fossil contents, and that as a whole they were 
 entitled to be ranked in schemes of classification as a system 
 of sedimentary deposits. It was also found that while all 
 
202 TERTIARY TIMES. 
 
 these sediments, or rather formations of sediments, were 
 highly fossiliferous, they were covered over, at least in the 
 greater portion of the northern hemisphere, by thick masses 
 of bonldery clay and gravel, devoid, or all hut devoid, of 
 fossils; and this bouldery clay was considered as necessarily 
 limiting or closing the system. In this way the Tertiary 
 of the earlier geologists became to be broken up into Ter- 
 tiary and Quaternary the former embracing all the strata 
 that lie between the Chalk and Boulder-Clay, and the 
 latter the boulder-clay and all those superficial accumula- 
 tions that have since been formed, or are still in process of 
 formation, by the ordinary agencies of nature. Tabulating 
 this arrangement, we have the 
 
 QUATERNARY, or POST - TERTIARY, embracing all the 
 superficial clays and gravels, the peat-mosses, swamp- 
 growths, coral-reefs, lake-silts, 'estuary-silts, and sea- 
 silts, with the boulder-clay beneath ; and the 
 
 TERTIARY, all the regularly stratified clays and gravels, 
 marly limestones, gypsums, and lignites or brown- 
 coals, that lie between the Boulder-Clay and the Chalk 
 formations. 
 
 In other words, the Quaternary or Post-Tertiary embraces 
 the rocks and records of the current epoch ; the Tertiary, 
 the rocks and records of a period that long preceded. And 
 this not a brief period, but one of long continuance so 
 long, that during its currency there were many oscillations 
 of sea and land, many extinctions of genera and species, 
 and many introductions of other and newer races. 
 
 As might be expected in a system embracing a long 
 period of time, the rocks and fossils of the earlier tertiaries 
 differ considerably from those of the later ; and hence their 
 familiar arrangement into lower, middle, and upper; or 
 
THEIR ROCK-FORMATIONS. 203 
 
 into eocene, miocene, and pliocene, if we take, as Sir Charles 
 Lyell has done, the relative proportions of recent and fossil 
 shells which occur in the successive stages.* But whatever 
 the nomenclature we adopt, it is clear that the clays, sands, 
 gravels, marls, limestones, gypsums, and lignites which con- 
 stitute the tertiary system are the varied sediments of lakes, 
 estuaries, and shallow seas; and that in general the extent 
 and boundaries of these areas of deposit are more apparent 
 than those of the earlier systems. Indeed, many of the 
 tertiary deposits occupy limited spaces in the existing 
 continents, and thus we are led to infer that something 
 like the present distribution of sea and land had then begun 
 to prevail. At all events, much of the existing dry land 
 was then above water, and supplied the material for the 
 sediments, as well as the habitats for the terrestrial flora 
 and fauna of the period. Of course, it is not contended 
 that the continents had then assumed their present outlines, 
 nor that many lands then existing are not now submerged ; 
 but it is indicated that there is considerable relationship 
 between Tertiary and Recent times, and that the fossils of 
 the Old World tertiaries are more akin to the living plants 
 and animals of the Old World than to those of the New ; 
 while, on the other hand, the tertiary fossils of the New 
 World bear a striking resemblance to the plants and 
 animals that still flourish there. In other words, we are 
 approaching in tertiary times more nearly to the existing 
 ordainings of nature, and may therefore expect a closer 
 
 * Taking a hundred shells from the lower, a hundred from the middle, 
 and a hundred from the upper tertiaries of the London and Paris "basins, 
 Sir Charles found that only a small percentage (3 to 5) of existing species 
 occurred in the lower, hence eocene (Gr. eos, dawn ; Jcainos, recent), or 
 dawn of existing things ; that the number of existing species was some- 
 what less than the extinct (25 to 40) in the middle, hence miocene (meion, 
 less), that is, less recent than the existing ; and that in the upper the ex- 
 isting species exceeded the extinct (70 to 90), hence pliocene (pleion, more), 
 that is, more recent than the middle or lower divisions. 
 
204 TERTIARY TIMES. 
 
 resemblance in all the phenomena, physical and vital, than 
 it was possible to trace between the present and any of the 
 remoter epochs.* 
 
 As Eocks there is nothing difficult to comprehend either 
 in the nature or composition of the tertiary sediments. In 
 one basin or area of deposit we have alternations of sands, 
 gravels, clays, and lignites ; in another, sands, gravels, clays, 
 limestones, gypsums, and lignites; and in a third, clays, 
 lignites, marls, and interstratified overflows of lava or showers 
 of volcanic ashes. All these alternations are well displayed 
 in the tertiary basins of London, Hampshire, Paris, Au- 
 vergne, the Lower Ehine, and Vienna; and the observer 
 has no greater difficulty in comprehending the nature of 
 these successions than he has in interpreting the sediments 
 of any lake or estuary of the present day. In. some basins 
 the limestones may be hard and compact, or even siliceous, 
 like the burr-stone of Paris ; in others the sands may be 
 consolidated into sandstones ; in some, the lignites may be 
 peaty and woody, while in others they are scarcely distin- 
 guishable from ordinary coal ; but taking them all in all, 
 the tertiary strata present few difficulties either as regards 
 composition or the agencies concerned in their formation. 
 In some of the areas of deposit, as evidenced by their fossils, 
 the strata are strictly marine, in others they are fresh-water 
 or lacustrine, and in some, again, there is an admixture of 
 sea and river silts, which are consequently regarded as estu- 
 arine or fluvio-marine. Just as at the present day such 
 seas as the Adriatic, Euxine, and Caspian are receiving their 
 
 * The reader who will take the trouble to consult a geological map of 
 Europe will see at a glance that much of the continent was occupied by 
 seas and lakes during the Tertiary period, and that it was not till towards 
 the close of the epoch that as a land-mass it began to assume its existing 
 configuration and dimensions. As with Europe, so to a great extent 
 with Asia and Africa, but notably so with North and South America. 
 The great land-masses had then been merely blocked out, as it were ; their 
 existing aspects are the results of Tertiary and Quaternary modifications. 
 
THEIR FLORA AND FAUNA. 205 
 
 sediments contemporaneously with the deltic deposits of the 
 Po, Danube, and Volga, and these again contemporaneously 
 with the silts of the Venetian and Hungarian lakes ; so in 
 tertiary times the same sort of operations went simultane- 
 ously forward, and thus we find throughout the system a 
 variety not only of sediments, but of fossils, though all 
 belonging to one great and continuous period of world- 
 history. 
 
 There were also throughout the deposition of the tertiary 
 strata abundant manifestations of volcanic activity, and in 
 few tertiary districts are there wanting the cones, crateri- 
 form hills, lava overflows, ash-beds, and trachytic tufas that 
 mark the comparative recentness of their production. In 
 Central France, the Lower Ehine, Italy, Hungary, Greece, 
 Western and Central Asia, Australia, and 'New Zealand, 
 such evidences are everywhere abundant, and even in our 
 own islands the basalts of Antrim and the trap-tuffs of Mull 
 present their concurrent testimony. Less crystalline than 
 the greenstones, felstones, and porphyries of the secondary 
 and primary periods, and more compact than the lavas and 
 cinder-beds of the present day, the tertiary traps are readily 
 distinguished ; and even where most consolidated, their age 
 is easily determined by the associated strata. In Auvergne, 
 the Lower Ehine, and Greece, they are found with beds of 
 eocene and miocene age ; in Australia, basaltic overflows 
 cover auriferous gravels of pliocene date ; and in New Zea- 
 land they spread over lignites of perhaps still later origin. 
 
 As a Life-period the tertiary system stands in remarkable 
 contrast with all that we know of the preceding formations. 
 In these the scheme of life, as now known to us, was incom- 
 plete either some great order being largely predominant, 
 or one or more orders altogether wanting. Taking the 
 fauna alone, the Laurentian, Cumbrian, and Silurian were 
 
206 TERTIARY TIMES. 
 
 characterised by the general absence of vertebrata ; in the 
 Old Ked Sandstone we had no reptiles, nor birds, nor mam- 
 mals; in the Coal no birds nor mammals; and in the 
 secondary ages nothing apparently higher than marsupials. 
 But now, and for the first time in the history of the earth, 
 we are presented with all the great orders of plants and 
 animals, and were it not for certain forms that have become 
 extinct and others that are peculiar to the current epoch, 
 we could almost fancy we were dealing with the botany and 
 zoology of the present day. So far as they have been criti- 
 cally examined, the plants of the lower European tertiaries 
 indicate a much warmer climate than now prevails over the 
 same latitudes ; and this higher temperature was in all like- 
 lihood brought about by the peculiar disposition of the sea 
 and land. Broad rivers flowing from tropical latitudes, and 
 inland seas extending longitudinally into sub-tropical or 
 even tropical zones, would be sufficient to account for the 
 presence of palms and other allied vegetation in the lignites 
 of Europe ; and what we already know of the boundaries 
 of the lower tertiaries, affords the best reason for believing 
 that such were the great geographical arrangements of the 
 period. In our reasonings on former climates we are too 
 apt to look to mere zones of latitude, without sufficiently 
 allowing for disposition and altitude of land, the trend of 
 oceanic currents, the prevailing set of winds, the effects of 
 atmospheric humidity, and other similar incidents by which 
 the luxuriance or sterility of life is often more immediately 
 affected than by mere propinquity to the equator. During 
 the deposition of the middle and upper tertiaries the climate 
 seems to have gradually declined, and the European lignites 
 of these periods exhibit a flora bearing a striking resem- 
 blance to that which now flourishes in North America. 
 "We say " European lignites," for the lignites of Eastern 
 Asia, of New Zealand, and of British America seem each to 
 
THEIR FLORA. AND FAUNA. 207 
 
 be characterised by its own peculiar plants, and these for the 
 most part having a general relationship to the existing vege- 
 tation of the same regions. It must be admitted, however, 
 that the flora of all the tertiaries lower, middle, and upper 
 requires much more minute botanical investigation ; and 
 till this is done, geologists can offer little more than mere 
 approximations to the conditions of the period. 
 
 Like the flora, the fauna of the lower tertiaries would 
 seem to imply the existence of genial conditions at once of 
 climate, food, and habitat. Gigantic sharks, turtles, cro- 
 codiles, and sea-serpents in the basins of London, Paris, and 
 the Ehine, indicate much warmer waters than these lati- 
 tudes now enjoy ; while elephantine, tapir-like, camel-like, 
 lion-like, and ape-like forms among their terrestrial fauna 
 point unmistakably to sub-tropical or tropical surroundings. 
 NOT is it mere variety of generic and specific forms among 
 these mammalia, but their huge size and vast numerical 
 abundance, that point in the same manner to favourable 
 conditions of existence. Indeed, one of the most remark- 
 able features in the life of the period is the vast bulk of 
 the mammalia as compared with the same orders still exist- 
 ing. This massiveness of structure runs throughout all the 
 divisions of the system lower, middle, and upper and 
 marks alike the tertiary fauna of Europe, Asia, America, 
 and Australia. If the number and magnitude of reptilian 
 forms that thronged the secondary waters have conferred 
 on that cycle the designation of " The Age of Beptiles," 
 the number and magnitude of mammalian forms that peo- 
 pled the tertiary lands may in like manner entitle this 
 period to be signalised as "The Age of Mammals." Pdlce- 
 otheres, or tapir-like beasts, huge as elephants ; sivatheres, 
 or antelope-forms, tall as giraffes ; megatheres, or sloths, 
 weightier than the weightiest hippopotamus ; glyptodons, or 
 armadilloes, that could enclose a score of the living species 
 
208 TERTIARY TIMES. 
 
 under their shields ; macrauchenes, or llama-forms, bulky as 
 camels; liymnodons, or hyaenas, stronger than tigers ; dipro- 
 todons, or kangaroos, heavier than oxen ; and colossoclieles, 
 or carapaced turtles, full fourteen feet in diameter, are but 
 random instances of the colossal structures that have been 
 exhumed from the sediments of the tertiary epoch. In 
 this respect the fauna of the period seems to corroborate 
 the idea that there is a culminating point in the life of 
 orders, as there is in the life of individuals a period 
 when they attain their maximum development in numbers, 
 variety, and magnitude, and after which they gradually 
 decline and disappear, to make way for some newer and 
 advancing order. Or as it has been put by one of the most 
 recent writers on systematic geology (Professor Haughton), 
 "it appears to be an almost universal law of life on the 
 globe, that each group of organic beings increased in size 
 and in importance in an uninterrupted line from the com- 
 mencement of its existence, until its members reached their 
 maximum in some short time I mean, short as com- 
 pared with their whole life-history after their original 
 creation and appearance upon the globe ; and it would 
 almost seem as if, having reached that maximum of de- 
 velopment, they then commenced a process of degeneracy 
 and decline." 
 
 Another remarkable feature in the tertiary fauna is the 
 prevalence of what are styled " intermediate forms," that 
 is, of creatures partaking of the characteristics of two or 
 more adjacent orders a sort of interfusion, as it were, of 
 families and genera, which now stand distinct and separate. 
 We have thus elephant-like tapirs, camel-like stags, giraffe- 
 like camels, horse-like antelopes, lion-like bears, tiger-like 
 hyaenas, and numerous other inosculating forms, which, 
 had they existed now, would have filled up more closely 
 the meshes of the great network of existence. Nor is it 
 
THEIR FLORA AND FAUNA. 209 
 
 among the mammalia alone that this gigantic size and 
 peculiarity of form make their appearance ; for birds, rep- 
 tiles, and fishes partake of similar characteristics, and point 
 to the same favourable conditions of growth, and to the 
 same great law of structural relationship and development. 
 We say structural relationship, for, as has been well re- 
 marked by Professor Jukes, " in speaking of these extinct 
 animals as forming links between our existing forms, we 
 must never forget that the living forms are not the types, 
 but the variations from the types. "We are apt to assume 
 that the forms with which we are most familiar are the 
 most simple and natural ; but the scientific naturalist often 
 finds some extinct form as the simple archetype, from which 
 numerous others have departed more and more by variation 
 and combination of parts in subsequent periods." We are 
 right when we speak of these tertiary mammals as holding 
 an intermediate place between some existing forms, but we 
 are wrong if we consider them on that account to be either 
 more complex in structure or varied in function. "A 
 three-toed horse (hippotherium) would now be looked on," 
 says Mr Woodword, " as a lusus naturae; but in truth, the 
 ordinary one-toed horse of the present day is by far more 
 wonderful." 
 
 We have already remarked, that though the distribution 
 of the tertiary seas and lands differed considerably from the 
 present, there must still have been a certain approximation 
 to the present arrangement, inasmuch as the tertiary flora 
 and fauna of every region, and especially of the later ter- 
 tiaries, bear a considerable resemblance to the plants and 
 animals that yet flourish there. There may be local differ- 
 ences among the tertiary basins of Europe and Asia ; but 
 still throughout the whole there is, if we may so phrase it, 
 an aspect of Old World forms. The species and genera 
 may differ, and there may be forms that stand intermediate 
 
 o 
 
210 TERTIAKY TIMES. 
 
 between two or three conterminous families ; yet, on the 
 whole, we see in the mastodons and mammoths, the palaso- 
 theres and anoplotheres, the hyopotami and chaeropotami, 
 the sivatheres and merycotheres, the machairodons and 
 hysenodons, the prototypes and forerunners of the elephants, 
 rhinoceroses, hippopotami, river-hogs, antelopes, giraffes, 
 camels, horses, oxen, lions, tigers, and hyaenas, that now 
 inhabit the eastern hemisphere. In like manner the me- 
 gatheres, mylodons, glyptodons, and macrauchenes of South 
 America, were the gigantic forerunners of the sloths, arma- 
 dilloes, and llamas that now people that continent ; while the 
 diprotodons, zygomatures, and nototheres of Australia, fore- 
 shadow the kangaroos and wombats so exclusively charac- 
 teristic of that peculiar sub-continent.* Everything, indeed, 
 both in flora and fauna, indicates the approach of existing 
 nature; but this, as in all other cosmical operations, by 
 slow and gradual steps the eocene, miocene, and pliocene, 
 each having its own special phases, and these diverging 
 from those of the current epoch according to their relative 
 distances in time. 
 
 What a picturesque and luxuriant scene these grassy 
 plains and glades and river -banks of the old tertiary times 
 must have presented ! Uplands fretted with scrub, la- 
 goons and river-creeks fringed with palms and tropical 
 forest-growths, and swampy deltas teeming with tangling 
 jungle. Herds of antelope- and horse-like forms (anoplo- 
 theres and hippotheres) scattered over the uplands j carni- 
 vora (hysenodon and cynodon) lurking among the rocks and 
 bushes by the water-springs ; elephants, tapirs, and wart- 
 hogs (mastodons, palseotheres, and hyopotami) down by the 
 
 * By a perusal of the illustrations in any work on Palaeontology, such as 
 Owen's ' Fossil Mammals/ the non-scientific reader will be enabled to trace 
 the resemblance between these extinct forms and the existing fauna far 
 more readily than by any amount of verbal description. 
 
THEIR ECONOMIC PRODUCTS. 211 
 
 river-side ; and huge amphibia (halitheres, diuotheres, and 
 crocodiles) lazily sunning themselves on the islets and mud- 
 banks of the far-spreading delta ! Plain, lake, estuary, and 
 sea, teeming alike with life during the warmer eocene; 
 abounding in milder forms during the still genial miocene ; 
 and gradually assuming more temperate aspects as the 
 pliocene approached more nearly to the ordainings of the 
 current epoch. Such were the leading aspects of the Ter- 
 tiary Times times enjoying the genial surroundings of a 
 peculiar geographical distribution of sea and land, and only 
 brought to a close by new terraqueous arrangements inimi- 
 cal (over the greater portion of the northern hemisphere at 
 least) to vegetable and animal luxuriance. 
 
 As Economic Repositories, the tertiary formations, though 
 greatly inferior to some of the older systems, are not with- 
 out their local importance. Brick and pottery clays, sands 
 for glass-making, fuller's earth, tripoli or polishing-stone,* 
 gypsum or plaster -of -Paris stone, limestones, burrh for 
 millstones, and a great variety of lignites or brown-coals 
 with their associated gums and amber, t are among their 
 
 * These polishing, infusorial, or microphytal earths are among the 
 most wonderful of tertiary and recent accumulations, alike from their 
 origin and the vast thickness to which they sometimes attain. Accord- 
 ing to Professor Dana, the infusorial earth of Virginia is in some places 
 30 feet thick, extends from Herring Bay in the Chesapeake, Maryland, to 
 Petersburg, Virginia, or beyond, and is throughout an accumulation of 
 the siliceous remains of microscopic organisms, mostly Diatoms. A still 
 thicker bed, exceeding 50 feet, exists, according to Mr W. P. Blake, on 
 the Pacific at Monterey, and is white and porous like chalk. The 
 " polishing powder " of Tripoli and Bilin, and the " mountain meal" of 
 Tuscany, Sweden, and other countries, are kindred accumulations. 
 
 t In some of the later lignites, like those of Northern Germany and 
 Bunnah, amber and other fossil gums and resins are found in all but 
 their original attachment to the trees from which they were exuded. 
 And in these ambers the insects of the tertiary forest are often as per- 
 fectly preserved as the specimens in the cabinet of the most fastidious 
 collector. 
 
212 TERTIARY TIMES. 
 
 most prevalent and valuable products. These lignites, in- 
 deed, are year after year being discovered in new areas, and 
 are rapidly rising in economic value, as the only fuel in 
 many localities either for household or for manufacturing 
 purposes. Germany, Italy, Austria, Hungary, Farther 
 India, New Zealand, Vancouver Island, the Northern 
 Prairies of America, and other regions, are each possessed 
 of their brown-coals, which will be more and more sought 
 after, and more and more valued, as manufactures, railways, 
 steamboats, and kindred modern appliances extend their 
 influence and demand the cheapest and readiest supply. 
 Compared with the older coals, many of the tertiary lignites 
 are no doubt inferior ; but as the demand increases better 
 methods of consumption will be invented, and many of the 
 objections obviated which now stand in the way of their 
 being more largely raised both for domestic and manufac- 
 turing purposes. There is thus no formation, however old 
 or however recent, that is not invested with industrial as 
 well as with scientific interest all that is requisite being 
 research to determine the nature of their products, and skill 
 sufficient to procure and apply them. 
 
ICE ITS FORMS AND FUNCTIONS. 
 
 ICE, DEFINITION OF GENERAL PHYSICAL PROPERTIES OF WATER 
 FORMATION OF ICE ITS OCCURRENCE IN THE ATMOSPHERE : HOAR- 
 FROST, SNOW, AND HAIL ITS OCCURRENCE ON FRESH WATER : 
 
 RIVER, LAKE, AND GROUND ICE ON SALT WATER : ICE-FIELDS, 
 ICE-PACKS, ICE-FLOES, ETC., IN POLAR SEAS ICE ON LAND : SNOW 
 AND SNOW-LINE, AVALANCHES, N^VB, GLACIERS THEIR CHAR- 
 ACTERISTICS ICEBERGS GENERAL RESULTS OF ICE-ACTION. 
 
 THERE is no substance in nature so protean in form, so 
 incessant in circulation, or so multifarious in its functions 
 as water. Now aeriform, now liquid, now solid ; now in 
 the ocean, now in the atmosphere, now percolating the 
 earth's crust, now coursing its surface and hurrying again to 
 the ocean ; now supplying the wants of plants and animals, 
 now wearing down the earth in one part, now accumulating 
 new material in another, and anon locked up, as water of 
 crystallisation, in the mineral structure of the globe for 
 ages. The sum of its existence is change ; the whole course 
 of its history a series of marvels. It is, however, only 
 with one feature of its existence, and with a small portion 
 of its history, that we have to do in the present instance ; 
 though we have necessarily to glance at its general deport- 
 ment under heat, the incessant modifier of its form, and the 
 great propeller of its circulation. 
 
 At ordinary temperatures, as every one knows, water 
 appears in the liquid state ; at high temperatures it passes 
 rapidly into the vaporiform condition, and at low temper- 
 
214 ICE ITS FOKMS AND FUNCTIONS. 
 
 atures it becomes solid and crystalline. At 39 Fahr., or 
 thereabouts, it appears to be at its maximum density ; at 
 that temperature and above it, under favourable conditions 
 of the atmosphere, it is incessantly passing off as invisible 
 vapour, and diffusing itself through the air; and at 212, 
 under the usual sea-level pressure of the atmosphere, it 
 boils, and is rapidly converted into steam. From 39 down 
 to 32, it appears to suffer little change in density; but at 
 and under 32 for fresh water, and 28J for salt, it is sud- 
 denly converted into the crystalline or solid state, and is 
 then known as ice. In this state it has expanded, become 
 lighter, and necessarily floats on its own liquid surface. 
 Ice, then, in ordinary language, is solid or frozen water. 
 From its crystalline structure it occupies more space than 
 when in a liquid state ; hence its lightness and flotation, 
 which are further increased by the number of air-cells which 
 are always less or more entangled in its mass.* Compared 
 with water at 60, whose specific gravity is 1, ice is found 
 to be only .912 ; hence it floats with about one-ninth of its 
 mass above water, and the remaining portion below. Being 
 formed at 32, ice may be said to be then in its normal 
 condition ; but at lower temperatures it slightly contracts, 
 as was long ago proved by experiments on the ice of the 
 Neva at St Petersburg, t It is this ice, its various aspects 
 and functions, that forms the subject of the present Sketch; 
 
 * It is only from water that has been subjected to boiling that ice free 
 from these air-cells can be obtained. 
 
 j- In further proof of this contraction, we may cite Sir James Eoss, 
 who says " We have often in the arctic regions witnessed the astonish- 
 ing effects of a sudden change of temperature during the winter season 
 upon the ice of the fresh- water lakes. A fall of thirty or forty degrees of 
 the thermometer immediately occasions large cracks, traversing the whole 
 extent of the lake in every direction ; some of the cracks opening in 
 places several inches by the contraction of the upper surface in contact 
 with the extreme cold air of the atmosphere." It is also partly by this 
 contractile force that the ice-barriers and ice-walls of the polar seas are 
 broken into floes and fragments. 
 
IX THE ATMOSPHERE. 215 
 
 its geological operations "being those, of course, to which 
 the attention of the reader will be more especially directed. 
 
 In treating of Ice in a popular way, it may be conveni- 
 ently arranged under three great categories ice in the 
 atmosphere; ice on land; and ice on water. The ice or 
 frozen water in the atmosphere is the great nursing parent 
 of the ice on land ; and the ice accumulated on the land 
 becomes in the long-run one of the most remarkable fea- 
 tures of the ice that floats on the water. As the vapour 
 that ascends from the ocean is condensed and falls as 
 rain on the land, and this rain finds its way again by runnel 
 and river to the sea ; so the vapour frozen in the air descends 
 on the land, where, accumulating for ages, it slowly grinds 
 and pushes its way once more to the ocean. In this way 
 all the forms of ice are inseparably connected in one great 
 and incessant round of circulation, and we only separate 
 them provisionally for the purpose of intelligible descrip- 
 tion. First, then, as regards the ice in the atmosphere, the 
 most casual observer must have noted the frequent forma- 
 tion of hoar-frost, snow, and haiL The rapid radiation of 
 heat from the earth's surface, by which the invisible vapour 
 of the atmosphere is converted into dew, has only to be 
 carried beyond the limit of 32, when hoar-frost is produced, 
 crisping the herbage, or floating, in still conditions of the 
 air, in clouds of crystalline spicules. A more rapid con- 
 densation of rain or vapour produces hail, which may occur 
 at all seasons and under every latitude, and may fall in soft 
 snowy drops, or pellets of ice, from the size of a coriander- 
 seed to that of a pigeon's egg, and often with destructive 
 effect on the crops of the farmer. Neither hail nor hoar- 
 frost, however, exercises any perceptible influence on the 
 rocky surface ; and it is chiefly in the condition of snow that 
 ice in the atmosphere becomes of interest to the geologist. 
 
216 ICE ITS FORMS AND FUNCTIONS. 
 
 Tliis snow, formed of frozen vapour, and composed of my- 
 riads of the most delicate geometrical crystals, occurs during 
 winter in all the higher latitudes, and at great elevations in 
 all latitudes, wherever the surrounding air falls below the 
 average of 32. As the atmosphere frequently consists of 
 strata of different temperatures, snow may he formed in the 
 higher regions, and yet in falling may pass through a warmer 
 stratum, and he melted into rain before it reaches the earth. 
 But in ordinary circumstances it falls on the land-surface in 
 soft downy flakes ; and if that surface be at or under 32, 
 it often accumulates in great thickness, and especially in all 
 the higher and colder regions. In the lower grounds it is 
 melted and carried off by the next thaw ; in the higher 
 mountains, where it falls in dry needle-like crystals,* and 
 rarely or ever in flakes, it may endure, summer and winter, 
 for generations. But even there it cannot remain un- 
 changed ; summer suns and the pressure of newer accumu- 
 lations condense and urge it downwards first as neve^ or 
 snow-ice, and ultimately as the pure transparent ice of the 
 glacier. Here, however, it becomes ice on land, and falls to 
 be considered under a different section of our subject. 
 
 Like ice in the atmosphere, ice on land occurs chiefly in 
 the higher latitudes and at great elevations ; though under 
 a clear sky and extreme night-radiation, ice may be formed 
 on the ground even in sub-tropical and 'tropical countries. J 
 
 * The sands of the burning desert are not so light nor so easily moved 
 as this dry crystalline snow-powder of the loftier mountains. The slightest 
 breath disturbs it ; the storm-wind sweeps it from the exposed heights,, 
 and drifts it into the sheltered gorges in masses hundreds of feet in 
 thickness. 
 
 f Nev$ the name given to the stratified slightly - compressed snow 
 of the higher Alps before it is condensed into the crystalline ice of the 
 glacier. 
 
 + The destructive effects of these night-frosts, under a clear, dry, and 
 serene sky, are now unfortunately too well known to our Australian sheep- 
 
ON THE LAND. 217 
 
 In our own islands, every one must have witnessed the 
 effects of frost on the rocks and soils. The water held in 
 the pores of all rocky substances is rapidly converted into 
 ice; in this state it expands, pushes asunder the par- 
 ticles, and when thaw comes, the separated particles, having 
 lost their cohesion, necessarily fall asunder, and are ready 
 to "be carried away by winds, rains, and runnels of water. 
 The force with which water expands in freezing is tremen- 
 dous. The strongest vessels are burst asunder ; the hardest 
 rocks are split into chips and fragments. Every winter we 
 see its effects in the disintegration of our ploughed soils, 
 and in the mounds of debris at the foot of our cliffs and 
 precipices. But under our insular climate the effects are 
 trilling compared with what takes place in higher latitudes 
 and in more elevated regions. In the higher Himalayas Dr 
 Hooker found the cliffs and precipices rent and rugged with 
 its force, and the ravines choked with the ruptured blocks 
 and fragments ; in Norway every peasant can point to the 
 mounds of angular blocks as the work of the " Bergrap ; " 
 and in Spitsbergen the Spanish Expedition found the 
 sea-cliffs fresh with recent rupture every winter severing 
 with its icy wedge, and every summer dissolving the connec- 
 tion. It is needless, however, to multiply instances ; every 
 intelligent mind must perceive the power of this recurring 
 ice-force, and its universality, in all the colder and higher 
 regions of the globe. And he has only to allow sufficient 
 
 fanners. Even in the deserts of Africa, Arabia, and Persia, European 
 travellers have felt their effects. In Bengal, where ice is never formed 
 naturally, advantage is taken of the principle for its artificial pro- 
 duction. Shallow pits are dug, which are partially filled with straw, 
 and on the straw flat pans, containing water which has been boiled, are 
 exposed to the clear, dry, and serene firmament. The water is a power- 
 ful radiant, and sends off its heat rapidly into space. The heat thus 
 lost cannot be supplied from the earth, this source being cut off by the 
 non-conducting straw ; and before sunrise a cake of ice is formed in each 
 vessel 
 
218 ICE ITS FORMS AND FUNCTIONS. 
 
 duration, and every peak and precipice would be rounded 
 and worn down by its power.* 
 
 In all the higher latitudes, snow, we have said, falls less 
 or more during winter, and melts away during summer, t 
 But in all latitudes there is an elevation at which it lies 
 perennially, and this elevation will differ, of course, with 
 the latitude. This limit, above which snow lies at all 
 seasons, is known as the snow-line, or line of perpetual con- 
 gelation; and though it ascends a little higher during sum- 
 mer, and descends a little lower in winter, it is, on the 
 whole, pretty stationary in every region of the globe. Of 
 course, it will come nearer the sea-level in high latitudes, 
 and ascend higher and higher as we approach the equator ; 
 and thus it is that we have it at 1500 feet in Spitzbergen, 
 2400 at North Cape, 5000 in the Dovrefelds, 9000 in the 
 Alps, 12,000 in the Atlas range, and on an average about 
 16,000 feet under the equator. In all the higher regions, 
 therefore, this snow accumulates enormously, and would 
 continue to accumulate were it not for three causes which 
 tend as incessantly to prevent it. These are, first, atmo- 
 spheric causes, such as summer's heat, warm winds, and 
 occasional rainfalls, which partially dissolve it ; second, the 
 mechanical pressure of the accumulating mass, which ever 
 tends to urge it forward and downward to lower levels; and, 
 third, the land-slopes, which afford greater or less facilities 
 for its descent. As it descends by these means, so it melts 
 
 * The reader who takes interest in this matter will find marvellous illus- 
 strations of the power of frost in such works as Von Wrangell's ' Siberia, ' 
 Scoresby's 'Arctic Voyages/ Ross's 'Antarctic Voyages/ and Dr Hooker's 
 ' Himalayan Journal.' 
 
 *{ Though snow is the necessary product of cold, yet in all temperate 
 and coldly-temperate latitudes a good heavy snowfall is beneficial in pro- 
 tecting vegetation from the severity of long- continued frosts. Such a cover- 
 ing is usually known as the snow-blanket, and in central and northern 
 Europe its absence in early spring is often followed by most destructive 
 results to the young growths of the farmer and gardener. 
 
ON THE LAND. 219 
 
 away, and is carried by runnel and river to the ocean, again 
 to be raised as vapour, again to be frozen and fall as snow, 
 and again to be urged downward and melted to water. 
 Occasionally its descent from the mountains is sudden and 
 abrupt, as in the avalanche, which breaks away when the 
 gravity of the mass becomes too great for the slope on which 
 it rests, or when fresh weather' destroys its adhesion to the 
 surface. These snow-slips, or rather snow-and-ice slips, 
 are frequently most destructive in their effects, and are the 
 dread of the traveller and inhabitant on mountain regions 
 like the higher Alps and Himalaya. These are usually 
 distinguished as drift 9 or those caused by the action of the 
 wind on the snow while loose and powdery ; rolling, when 
 a detached piece of snow rolls down the steep, licks up the 
 snow over which it passes, and thus acquires bulk and im- 
 petus as it descends ; sliding, when the mass loses its adhe- 
 sion to the surface, and descends like a land-slip, carrying 
 everything before it unable to resist its pressure; and glacial, 
 when masses of frozen snow and ice are loosened by the 
 heat of summer, and precipitated with crushing effects into 
 the valleys below. 
 
 The great and persistent result, however, of this moun- 
 tain-snow, is the glacier the " ice-sheet " of the flatter 
 heights, and the " ice-river " of the glens and ravines 
 which is ever pushing and grinding its downward way till 
 it finally melts and becomes the gladdening stream of the 
 lower valleys. The snow that falls on the higher peaks, 
 being partially softened by the warmth and rains of sum- 
 mer, is converted into a sort of " snow-broth," or " slush," 
 as the Scotch would call it, and has necessarily a tendency 
 to move downward by its own gravity, however gentle the 
 slope on which it rests. Pressed on summer after summer 
 by newer masses, it gradually assumes greater consistence, 
 loses the dull aspect of frozen snow, and passes into the hard 
 
220 ICE ITS FORMS AND FUNCTIONS. 
 
 transparent state of the glacier or ice-river. In its primary 
 stage it is technically known as neve or ice-snow; and this 
 neve", which stands intermediate between the pure unsunned 
 snow of the winter heights and the moving glacier, is re- 
 garded as the fond or fountain of all true glaciers. Ever fed 
 by new snowfalls from above, it is gradually pushed down- 
 wards by the force of gravitation, and in turn propels the 
 glacier, whose own weight and partial mobility also assist 
 the downward movement. The whole is, in fact, one great 
 motion, just as it is part of the great circulation by which 
 the water of the ocean is disseminated through the air and 
 over the land, and the water of the land returned once 
 more to the ocean. Acquiring volume and weight as it 
 descends (and some of the Alpine glaciers are from 80 to 
 600 feet in thickness), the glacier grinds and smoothes the 
 rocks over which it passes ; and this it does by the earth, 
 gravel, and rock-debris which become incorporated with its 
 mass, and which act like so many rasps and chisels on the 
 rocky surface. Slow in its motion, but persistent and irre- 
 sistible, its course is ever downwards, and marked by abra- 
 sion, rounding, smoothing, and striation of the subjacent 
 rocks. And as it descends, the blocks and debris, loosened 
 by the frost from the adjacent cliffs, fall on its surface, and 
 are borne along in long winding spits, till the mass finally 
 melts away in the lower valleys, and then this rock-debris 
 is left in mounds or moraines. These moraines some of 
 which are lateral, or on the sides ; some medial, or in the 
 middle ; and some terminal, or at the melting end bear 
 ample testimony of the destruction that has taken place 
 among the rocks above, and yet it is but a small portion 
 of what has been discharged as impalpable mud by the dis- 
 coloured stream that issues from the glacier. 
 
 Wherever glaciers occur and they can only occur in 
 mountains above the snow-line, and in regions where there 
 
ON THE LAND. 221 
 
 is atmospheric moisture sufficient to produce continuous 
 snows their great geological function is to round and 
 smooth down all rocky asperities, to round off projections, 
 and produce roches-moutonnees as they are termed, to en- 
 large and deepen rock-basins, and to grind out and furrow 
 the mountain glens down which they descend. And this 
 descent, though obstructed by inequalities of surface, or re- 
 tarded by the frosts of winter, never ceases. Cracked and 
 crevassed as the ice-mass may be by the thaw of summer, 
 hard and snow-clad as it is during the frosts of winter, it is 
 still on the move, as persistent as gravitation itself, and as 
 continuous as the snowfall by which it is created. This 
 characteristic motion is thus summed up by Principal Forbes 
 in his truly philosophical work * On the Theory of Gla- 
 ciers : ' 1. That the downward motion of the ice from the 
 mountains towards the valleys is a continuous and regular 
 motion, going on day and night without starts or stops. 
 2. That it occurs in winter as well as in summer, though 
 less in amount. 3. That it varies at all times with the 
 temperature, being less in cold than in hot weather. 4. 
 That rain and melting snow tend to accelerate the glacier 
 motion. 5. That the centre of the glacier moves faster 
 than the sides, as in the case of a river. 6. That the sur- 
 face of the glacier moves faster than the bottom, also as in 
 a river. 7. The glacier moves fastest (other things being 
 supposed alike) on steep inclinations. 8. The motion of a 
 glacier is not prevented, nor its continuity hindered, by 
 contractions of the rocky channel in which it moves, nor 
 by the inequalities of its bed. 9. The crevasses are for 
 the most part formed anew annually, the old ones disap- 
 pearing by the collapse of the ice during and after the hot 
 season. 
 
 In the mountains of Norway, the Himalaya, and the Alps, 
 the glacier winds its way down the glens and hollows till it 
 
222 ICE ITS FORMS AND FUNCTIONS. 
 
 reaches a certain limit in summer, and a little beyond that 
 limit in winter ; but still there is a limit at which it melts 
 away and disappears, leaving its terminal mound of rounded 
 blocks and shingly debris. In higher latitudes, however, 
 such as Spitzbergen and Greenland, the ice-sheet that envel- 
 opes the land comes down to the sea-shore, and, ever urged 
 forward by the formation of newer ice inland, even projects 
 its icy wall far into the sea. But being lighter than water, 
 there is a limit beyond which the mass, thick and heavy as it 
 may be, cannot pass, and then it becomes buoyant, is broken 
 off by storms, and drifted by winds and tides and currents 
 as the iceberg over the surface of the deeper ocean. It is 
 thus that the glacier, whether disappearing on the slopes of 
 the mountain or melting away in the ocean, fulfils the beau- 
 tiful saying of De Boue, that " it begins in the clouds, is 
 formed by the mountains, and ends in the ocean." These 
 icebergs or ice-mountains are often of gigantic size, being 
 several miles in circumference, and rising 50, 100, or 200 
 feet above the water.* And when it is borne in mind that 
 
 * The icebergs of the antarctic seas are generally larger, more preci- 
 pitous, and more tabular in form than those of the arctic ; while those 
 of the latter, on the other hand, are more heavily laden with boulders, 
 shingle, and land-worn debris. Sir James Eoss thus adverts to some of 
 the former : " To-day (Jan. 31, 1841) several icebergs were seen ahead 
 of us. They were chiefly of the tabular form, perfectly flat on the top, 
 precipitous in every part, and from 150 to 200 feet high. They had 
 evidently, at one time, formed part of the barrier (the great ice-barrier 
 that prevented his approach to the southern pole, and which was es- 
 timated at more than 1000 feet in thickness), and I felt convinced, from 
 finding them at this season so near the point of their formations, that 
 they were resting on the ground. The lines were immediately prepared, 
 and when we got amongst them next morning we hove - to, and ob- 
 tained soundings in 1560 feet, on a bottom of stiff green mud, leaving 
 no doubt on our minds that all the bergs about us, after having broken 
 away from the barrier, had grounded in this curious bank, which, 
 being two hundred miles from Cape Crozier, the nearest known land, 
 and about sixty from the edge of the barrier, was of itself a discovery 
 of considerable interest," 
 
ON THE LAND. 223 
 
 little more than an eighth of the mass makes its appearance 
 above the surface, one can readily form some conception of 
 the bulk and weight of a " berg," and of its crushing and 
 grinding power when drifted along at the rate of four or 
 five miles an hour. But the ice that was generated on 
 and has now become ice on water, and belongs to the next 
 division of our subject. 
 
 But before taking leave of ice as it appears on the land, 
 there is another condition in which it not unfrequently 
 occurs, and which is well deserving of the attention of the 
 geologist and hydrographer. We allude to its formation 
 and conservation in caverns and fissures where it may have 
 lain unchanged for ages. These ice-caves, as they are called, 
 are found in many countries, and most abundantly, of 
 course, in all high, dry, and cold regions. In some the ice 
 appears in stalactitic and stalagmitic masses, issuing from 
 the roofs in fantastic cascades and wall-like screens, or rest- 
 ing on the floor in cones and pillars ; in some it merely 
 forms a pavement of varying thickness ; while in others it 
 glitters on all sides like a casing of the purest alabaster. 
 Palseontologically, the preservative effects of such cavern ice 
 must be very great; hydrographically, its partial melting 
 in summer may feed the mountain-springs that would other- 
 wise be dry; and economically, it yields to the surrounding 
 districts its cooling and refreshing supplies. In Europe 
 the better-known ice-caves or glacieres, as they are locally 
 termed, occur in France and Switzerland, and those form 
 the subject of a recent volume by the Eev. G. F. Browne, 
 a perusal of which will well repay the reader.* As the 
 subject is somewhat novel, the theory of their formation, 
 as given by Deluc and the author, may prove instructive ; 
 and this we present with a little condensation : 
 
 " The heavy cold air of winter," says Mr Browne, " sinks 
 * 'Ice- Caves of France and Switzerland.' Longmans & Co. 1865. 
 
224 ICE ITS FORMS AND FUNCTIONS. 
 
 down into the glacieres, and the lighter warm air of summer 
 cannot on ordinary principles of gravitation dislodge it, so 
 that heat is very slowly spread in the caves \ and even 
 when some amount of heat does reach the ice, the latter 
 melts but slowly, for ice absorbs 60 C. of heat in melting ; 
 and thus when ice is once formed, it becomes a material 
 guarantee for the permanence of cold in the cave. For this 
 explanation to hold good it is necessary that the level at 
 which the ice is found should be below the level of the 
 entrance to the cave; otherwise the mere weight of the 
 cold air would cause it to leave its prison as soon as the 
 spring warmth arrived. In every single case that has come 
 under my observation this condition has been emphati- 
 cally fulfilled. It is necessary also that the cave should be 
 protected from direct radiation, as the gravitation of cold 
 air has nothing to do with resistance to that powerful means 
 of introducing heat. A third and very necessary condition 
 is, that the wind should not be allowed access to the cave ; 
 for if it were, it would infallibly bring in heated air in spite 
 of the specific weight of the cold air stored within. There 
 can be no doubt, too, that the large surfaces which are avail- 
 able for evaporation have much to do with maintaining a 
 somewhat lower temperature of the place where the air 
 occurs. Another great advantage which some glacieres 
 possess must be borne in mind namely, the collection of 
 snow at the bottom of the pit in which the entrance lies. 
 This snow absorbs in the course of melting all which strikes 
 down by radiation, or is drawn down by accidental turns 
 of the wind ; and the snow-water thus forced into the cave 
 will at any rate not seriously injure the ice." So much 
 for ice as it appears on the land ; let us next turn to its 
 aspects and functions on the water. 
 
 The last and most obvious division of our subject, per- 
 
ON WATER. 225 
 
 haps, is that of ice on water. In all the temperate and 
 colder latitudes this is a common winter phenomenon 
 occurring whenever the thermometer falls below 32, and 
 most rapidly in clear, dry, and serene conditions of the 
 atmosphere. Every one who has watched by the stagnant 
 pool must have observed the first formation of ice a creep- 
 ing or shrinking, as it were, of the surface occasioned by the 
 incipient ice-crystals, which shoot hither and thither, inter- 
 lace, and coalesce till a thin continuous crust has gathered 
 over the whole. This is the first film ; and as freezing 
 takes place from above,* every successive film is formed 
 more slowly ; the ice-crust as it thickens protecting more 
 and more from the cold the water that lies below. Indeed 
 it is often curious to observe how little will obstruct the 
 radiation of heat and prevent the formation of ice. An over- 
 hanging tree, a few leaves drifted over the first film, or even 
 a cloudy sky, is sufficient to retard or obstruct ; and though 
 a clear and serene sky be in general most favourable, yet an 
 air of dry wind to remove any superincumbent vapour will 
 materially promote the operation. As the frost continues 
 the ice thickens, but not indefinitely, for in water of suffi- 
 cient depth this thickening acts as a barrier to its further 
 increase, and even in the coldest regions it is only the shal- 
 lower waters that are ever completely converted into ice. 
 Besides the ice that forms on the surface of fresh water, 
 
 * This principle of freezing from above is not sufficiently taken advan- 
 tage of by our skaters, curlers, and ice-storers. Instead of waiting till 
 the frost has produced a sufficient thickness of ice in the natural way 
 a thing never to be depended on in our uncertain climate they ought 
 to have the water let by degrees over the surfaces of the already formed 
 ice, and in this way its thickness and strength would be rapidly aug- 
 mented. We believe the celebrated ice of Lake Wenham, now so largely 
 used in and exported from North America, is treated in this way each 
 successive surface being scraped and cleaned before the next overflow 
 of water. For hardness, transparency, and general beauty of mass, the 
 Wenham ice is unrivalled. 
 
226 ICE ITS FORMS AND FUNCTIONS, 
 
 there is occasionally witnessed the rarer phenomenon of 
 ground-ice, or that which gathers in thin sheets along the 
 pebbly beds of shallow lakes and streams. These pebbles, 
 losing their heat by radiation quicker than the water for 
 heat radiates through as it does from the surface of the 
 transparent water act as points for the formation of ice- 
 crystals, and these passing from stone to stone, shortly 
 convert the entire pebbly bed into a crust of ice. We have 
 seen in a shallow ford of a Scottish stream ground-ice fully 
 an inch in thickness when the stream itself was still flowing 
 and unfrozen. This ground-ice, when broken up by freshets 
 or other causes, floats down the stream, bearing with it its 
 burden of encrusted pebbles, and thus becomes in nature a 
 curious means of geological transport. Pebbly gravels may 
 thus be laid down in situations where no current of water 
 could carry them ; just as Deas and Simpson found the ice- 
 cake of the arctic shores driven forty or fifty feet above the 
 sea-level, and as it melted away, leaving long ridges of 
 beach -gravel at heights to which no ordinary wind -wave 
 could ever transport it. 
 
 But important as the formation of ice on fresh-water 
 lakes and streams may be, it is as nothing compared with 
 the masses that accumulate on the surface of the arctic 
 and antarctic seas. Instead of forming at 32, ice does 
 not appear on salt water till the temperature has sunk 
 to 28J ; and then it goes on increasing, according to 
 Sir Edward Belcher,* at the rate of about half an inch 
 per day, during the long polar winters, often attaining 
 a thickness of 10, 15, and 20 feet. This enormous 
 crust, as it stretches unbroken over the ocean, is the 
 
 * Sir Edward's observations were made in Wellington Channel (1852- 
 54) when in search of the missing Franklin Expedition. See his Nar- 
 rative for some curious and instructive facts respecting the formation, 
 character, and deportment of polar ice. 
 
GENERAL REVIEW. 227 
 
 " ice - field " of the sailor, which, when broken up, be- 
 comes his "ice-brash," and either floats away in "floes" 
 and "patches," or is drifted by winds and currents in 
 " packs " and " streams." * The conservative effect of this 
 ice-crust on the 'warmth of the ocean is one of the most 
 providential arrangements in nature maintaining for the 
 water beneath the mean of 39, when in the air above the 
 cold is often sufficiently intense to solidify mercury, whose 
 freezing point is 39, or 39 below zero. Gradually as 
 the ice thickens, it protects more and more the subjacent 
 water ; t gradually as the water in contact with the under 
 surface of the ice is chilled, it becomes heavier, and sinks, 
 its place being taken by a warmer film ; and gradually as 
 the water is converted into ice (it freezes fresh, or only with 
 such brine as maybe entangled in its interstices), the upper 
 film, being salter and denser, descends, and lighter and 
 warmer particles ascend to take its place. In freezing, 
 water, of course, gives but heat, and the heated air-bubbles 
 may often be seen clustering beneath the ice and struggling 
 as it were to escape upwards. Every bubble in this way 
 
 * The names by which the different conditions of sea-ice are known to 
 our whalers and navigators. The "ice-field" or "field of ice " is the 
 unbroken ice of the polar oceans ; when broken up by thaws and storms 
 it becomes " brash-ice ; " when drifted into dense masses it is " pack- 
 ice ; " and when floated away by winds and currents it passes either into 
 solitary " floes," into " patches " of several floes, or into " streams," 
 having a determinate direction. A solitary fragment floating with a 
 considerable portion of its bulk above water is a " hummock ; " and 
 when loaded with debris and chiefly under water it is a " calf." The 
 young ice that is rapidly formed, on the approach of winter, between 
 floes and patches is "pancake ice;" when of greater thickness, and 
 formed in creeks and inlets, it is "bay-ice." These different conditions 
 are also known at a distance by their " blink " or reflection this being 
 clear for field-ice, white for packed, grey for newly formed, and deep yellow 
 for snow. 
 
 t As ice slightly contracts at temperatures under 32, the intense cold 
 of the polar regions only tends to render it more homogeneous and com- 
 pact, and thus to increase still further its powers of protection. 
 
228 ICE ITS FORMS AND FUNCTIONS. 
 
 melts its modicum of ice, and one by one, as they ascend in 
 the same direction, they gradually pierce the thickest sheet, 
 cutting rounded holes as clean and straight (in the words of 
 Sir E. Belcher) as if they had been bored by an auger. In 
 general, however, the heat is retained and diffused through- 
 out the water, while all above is stark and lifeless at tem- 
 peratures 50, 60, and even 70 below zero. How wonder- 
 ful the provision by which the density and temperature of 
 the ocean are preserved for the wants of its animal life ! 
 how perfect the scheme of compensation by which the most 
 powerful agents are held in check, and the balance and 
 equipoise of nature sustained ! 
 
 It is at this stage, when the thaws and currents of a brief 
 summer have broken up the polar ice into " floes " and 
 " packs " and " streams," that we find it associated with the 
 land-formed "berg;" the whole drifting to warmer lati- 
 tudes, there to be dissolved, and to lose themselves once 
 more in the liquid mass of the ocean. Purely sea-formed 
 ice has no perceptible geological effect, but much of it is 
 accumulated along shore and under cliffs and precipices 
 (the " ice-foot " of the sailor), and this, along with the true 
 iceberg, is generally laden with soil, sand, gravel, bouldery 
 blocks, and other spoils of the land, and these, as the ice- 
 masses melt away, are dropped broadcast over the floor of 
 the ocean. All that is, or has ever been, ground and worn 
 from the surface of Greenland by the ice-sheet that envelops 
 it, has been spread by the iceberg on the bottom of the 
 North Atlantic. Water in the solid state is as much a 
 wearer and transporter of the land as water in a liquid state. 
 The ice-stream grinds and degrades as surely as the water- 
 stream ; and the burden of both ultimately finds its way to 
 the depths of the ocean. Nay, ice is the more potent of 
 the two the " berg " bearing blocks and boulders which 
 no current of water could move, and scattering its burden 
 
GENERAL REVIEW. 229 
 
 over the outer depths of the ocean, while the river-sediment 
 is merely fringing the inner shores. 
 
 Such is a brief review of the various aspects in which ice 
 occurs, and the more prominent functions it appears to per- 
 form in the economy of nature. As snow in the lower 
 grounds, it acts as a protecting blanket against the severity 
 of long-continued frosts ; as snow in the higher regions, it 
 passes into neve and glacier to grind and round the rocky 
 surface in its descent, and to smooth into gentler outlines 
 the asperities over which it passes in its slow but irresis- 
 tible progress. As the liquid stream erodes and deepens its 
 channel, so the ice-stream rasps and chisels the function 
 of both being to wear and degrade the old rocks, and to 
 transport the material for the formation of the new. As 
 ice on water, its greater bulk, as compared with that of the 
 water from which it is formed, enables it to float as a 
 protecting surface, preventing the water below from being 
 entirely frozen, and thus preserving a habitable medium, no 
 matter how intense the cold, or however long it may be 
 continued. As ice on water also (the iceberg) it becomes 
 a geological carrier, transporting to the outer depths of the 
 ocean the gravel and shingle and boulders of the rocky 
 shores, and piling them up in long submarine reaches ac- 
 cording to the set of the tides and currents by which they 
 are mainly directed. As ice in the rocks and soils, it is ever 
 splitting and disintegrating; unless within the limits of 
 perpetually frozen ground, as in the tundras of Siberia and 
 the swamps of Arctic America, and there it exercises a con- 
 servative effect* binding the softest soils as hard as rocks, 
 
 * Even within these icy flats the power of frost is sometimes curiously 
 destructive. " The influence of the cold," says Von Wrangell, speaking 
 of the December temperature of Siberia, which was 58 below freezing, 
 " extends even to inanimate nature. The thickest trunks of trees are 
 rent asunder with a loud sound, which in those deserts falls on the ear 
 
230 ICE ITS FORMS AND FUNCTIONS. 
 
 and preserving their imbedded organisms fresh and un- 
 changed for ages.* In all its aspects, ice is invested with 
 a curious interest ; in all its functions it is charged with 
 important results. To us, the inhabitants of an insular 
 and unstable climate, it may appear of little importance ; 
 but to those of the higher latitudes and altitudes it assumes 
 the boldest character, and achieves the most gigantic re- 
 sults. And these results, when accumulated for years and 
 ages, present to the geologist, as we shall see in the follow- 
 ing Sketch, phenomena as marvellous in magnitude, and as 
 complicated in character, as those produced by any other 
 agency to which the crust of our earth is subjected. 
 
 like a signal-shot at sea ; large masses of rock are torn from their ancient 
 sites ; the ground in the tundras and in the rocky valleys cracks and forms 
 wide yawning fissures, from which the waters that were beneath the sur- 
 face rise, giving off a cloud of vapour, and become immediately changed 
 into ice." 
 
 * It is chiefly in the frozen sands and gravels of the Siberian lowlands 
 that the remains of the mammoth and woolly rhinoceros are preserved 
 in greatest perfection. Every geological reader is acquainted with the 
 history of the St Petersburg specimen ; how hair, wool, and muscle were 
 so fresh, when first discovered, that even the dogs of the Tungusian 
 hunters were tempted to feed upon them, and this after the entombment 
 of ages ! The manner of their occurrence is thus described by the autho- 
 rity above quoted : " The banks of the rivers consist of sand-hills 150 or 
 200 feet high, and held together by the perpetual frosts which the sum- 
 mer is too short to dissolve. Most of these hills are frozen as hard as 
 rock ; nothing thaws but a thin outside layer, which, being gradually 
 undermined by the water, often causes large masses of frozen sand to 
 break off and fall into the stream. When this happens, mammoth re- 
 mains, in more or less good preservation, are usually discovered." 
 
THE GLACIAL OK ICE EPOCH. 
 
 THE GLACIAL EPOCH AS DISTINGUISHED FROM THE PRE - GLACIAL 
 OR LATER TERTIARY ITS BOULDER-CLAYS, GRAVEL-DRIFTS, AND 
 ERRATIC BLOCKS LIMIT OF THESE IN THE NORTHERN HEMISPHERE 
 CONDITIONS UNDER WHICH THEY APPEAR TO HAVE BEEN FORM- 
 ED ICE-MANTLE, GLACIERS, AND ICEBERGS DURATION OF THE 
 PERIOD PAUCITY OF LIFE DEPRESSION AND RE -ELEVATION OF 
 LAND GRADUAL RETURN OF MORE GENIAL CONDITIONS ESTAB- 
 LISHMENT OF EXISTING ARRANGEMENTS, PHYSICAL AND VITAL 
 RECURRENCE OF COLDER AND WARMER CYCLES IN TIME. 
 
 THERE are few chapters in geological history possessed of 
 more interest than that which is usually known as the Gla- 
 cial Epoch, and none that has received a larger share of 
 attention from modern investigators. Indeed, it is still to a 
 great extent an unsolved problem, and hence the conflicting 
 views that prevail as to the physical conditions of the period, 
 and the causes by which these conditions were produced. 
 Though beset with many difficulties, the general features of 
 the period are well known, and it is to place these broadly 
 before the general reader, rather than enter upon debatable 
 hypotheses, that we attempt the present Sketch. 
 
 As mentioned in a preceding paper, the genial tempera- 
 ture that prevailed during the deposition of the earlier ter- 
 tiaries began gradually to decline during the middle and 
 later portions, till towards the close of the period an intense 
 cold set in, and ice seems to have prevailed alike over the 
 land and waters. Of course, we refer more especially to the 
 
232 THE GLACIAL OB ICE EPOCH. 
 
 higher latitudes of Europe, Asia, and North. America, the 
 regions within which the phenomena of the glacial epoch 
 are most strikingly displayed, and to which (from the 40th 
 or 42d parallel northwards) they were in all likelihood re- 
 stricted. Over these limits the ice-epoch long held its iron 
 sway, annihilating, or all hut annihilating, terrestrial life ; 
 grinding, and rounding, and moulding the land-surface as 
 no other agent but ice can do ; and loading the bottom of 
 the ocean with miscellaneous masses of mud, shingle, and 
 boulders. This paucity of life, these land-surfaces, and 
 these miscellaneous accumulations, are the principal proofs 
 of the conditions of the glacial epoch, and these we must 
 first consider under the knowledge we have gained by a 
 perusal of the preceding chapter. 
 
 At first it seems evident that towards the close of the 
 tertiary period the climate of a large portion of the northern 
 hemisphere was gradually growing colder and colder. In 
 all likelihood the land was somewhat higher than it is 
 now, and as this cold increased the loftier mountains would 
 become perennially enveloped with snow and glacier, arid 
 the surrounding seas with an annual covering of ice. Un- 
 der this increasing rigour all the more delicate tertiary 
 plants and animals would succumb, and those endowed 
 with greater elasticity of constitution would shift ground 
 to lower and more southern situations. As the cold still 
 increased, the ice-sheet seems to have spread itself even over 
 the lower grounds, to have pushed its way out to sea, and 
 during the thaw and currents of a brief summer to have 
 been drifted off in floes and bergs, as the ice is now from 
 the coasts of the arctic and antarctic regions. At this stage 
 the terrestrial flora and fauna would be at their minimum, 
 and paralleled, perhaps, by what we now find in Greenland 
 and the islands of the Arctic Ocean. During this setting-in 
 
ITS FIRST STAGE. 
 
 of the glacial epoch, the land, as we shall shortly see, seems 
 to have been gradually subsiding, and this subsidence went 
 on to the extent of 1800 or 2000 feet below the existing 
 sea-level, converting a large portion of what is now Europe 
 and America into series of frozen straits and ice-clad islands. 
 When the land seems to have been at its greatest depres- 
 sion the cold appears to have attained its greatest intensity, 
 and at this stage we have the zenith and turning-point of 
 the glacial period. After the lapse, perhaps, of ages, a re- 
 verse action sets in ; the land begins to be re-elevated ; a 
 new cycle of temperature commences ; and the cold, though 
 still clinging in snow and glacier to the higher hills, is less 
 felt along the lower grounds and neighbouring sea-shores. 
 By-and-by, as the elevation continues, the glaciers melt 
 away from the hill-sides ; the icebergs and ice-packs dis- 
 appear from the seas ; the general climate improves ; plants 
 and land animals in newer species gradually take posses- 
 sion of the land ; and the existing order of things is imper- 
 ceptibly established. Such seem to have been the setting-in, 
 the creeping-on, the culmination, and the departure of the 
 glacial epoch. Let us now glance at the proofs by which 
 this advent, this subsidence, and this re-elevation can be 
 logically established. 
 
 That the ice-epoch, like other great events in nature, 
 came on slowly and gradually, is abundantly evidenced by 
 the temperate or even coldly-temperate aspects of the flora 
 and fauna of the later, as compared with those of the middle 
 and earlier tertiaries. The eocene palms, crocodiles, turtles, 
 and monkeys do not appear in miocene strata ; the miocene 
 sycamores, chestnuts, and maples are replaced by pliocene 
 pines, beeches, and birches ; and thus over the tertiary areas 
 of Europe at least the declension of climate had been going 
 on for ages before the advent of the glacial period. How 
 far this declension was simultaneous over Asia and America 
 
234 THE GLACIAL OR ICE EPOCH. 
 
 has not been determined, but that a similar declension took 
 place in those areas is sufficiently obvious from a similar 
 change in their flora and fauna.* That the pre- glacial 
 land was somewhat higher than the present is shown 
 by old river-courses and land -surfaces that lie below the 
 existing sea-level, as well as by ice-marked rocks that dip 
 away beneath the waters. Had the pre-glacial lands been 
 lower, these rock -surfaces would not have been smoothed 
 and furrowed by ice, nor would the old land-surfaces have 
 made their appearance, t It was on this more elevated 
 surface, therefore, that the glacier and ice-sheet first began 
 their operations ; and it is at this stage that we find the 
 lowest tenacious clays ("lower till"), and angular blocks 
 and boulders, little removed from the rocks from which they 
 were severed. Here, then, we have the first stage of the 
 glacial epoch the operation of ice on a land-surface some- 
 what more elevated, in its average altitude at least, than the 
 existing continents of Europe, Asia, and North America. 
 This operation, as we have learned from the preceding 
 Sketch, must have been to grind and gouge in the valleys, 
 to smooth and round the higher eminences, and generally 
 to polish the harder rocks the detritus or abraded mate- 
 rial being carried forward to lower levels, there to be laid 
 
 * According to Professor Dana, there are no tertiary strata in North 
 America to the north of the New England States, the northern area having 
 been dry land while the southern was under water and received the ter- 
 tiary deposits. To this elevation of the northern lands, and the subse- 
 quent gradual uprise of the southern or tertiary portion to the height of 
 3000 or 5000 feet, he attributes the first setting-in of the glacial epoch. 
 
 t The attention of geologists has not been sufficiently directed to these 
 pre-glacial land-surfaces. It is true that the "lower till" rests for the 
 most part on abraded rock-surfaces, but there are many localities (we have 
 noticed them in Kincardine, Ayr, Fife, and Durham to say nothing of 
 the well-known Cromer beds in Norfolk) where it reposes on sands, 
 gravels, and even peaty beds, which were undoubtedly the soils and river- 
 gravels of the period immediately preceding ; and in these we may expect 
 to find the remains of the true pre-glacial flora and fauna. 
 
ITS SECOND STAGE. 235 
 
 down as clay and mud, mounds of shingly gravel, and 
 masses of blocks and boulders. Whatever the nature of 
 the parent rock, these mounds and masses would partake 
 of it yellow clays and schists and granites in granite dis- 
 tricts, red clays and red sandstone blocks in Old Eed 
 Sandstone areas, and dark -coloured clays and blocks of 
 limestone and sandstone in Carboniferous basins ; and as a 
 general rule these blocks and boulders not far transported 
 from the cliffs and precipices from which they had been 
 torn by the ice -giant. Indeed, in most instances, this 
 proximity of glacial clays, ice- worn and ice-scratched blocks, 
 is one of the best proofs of the first stage of the ice-epoch, 
 and all over the northern and middle portions of Scotland 
 we have never found it to fail in its indications. 
 
 Eut as the cold set in more intensely, the downward 
 movement of the land seems to have commenced ; and 
 hence much of the ice-worn debris of this first stage was re- 
 moved by denudation, step by step, as the terrestrial surface 
 descended. "What may have been the precise character of 
 the climate at this epoch of descent that is, how long the 
 winter frosts and how short the summer's thaw we have 
 no means of determining, for the earlier clays and moraine 
 blocks are destitute of organic remains ; but if we may 
 judge by the comparatively small amount of obliteration by 
 denudation, it would appear that the seas were more ice- 
 locked than free-flowing, and that consequently the land 
 went down encased, as it were, in ice of prodigious thick- 
 ness.* This descent or subsidence of the land forms the 
 
 * The ice-sheet at this stage may have been two or three thousand 
 feet in thickness. The great antarctic ice-barrier, met by Sir James Ross 
 and his companions, was estimated at a thousand or fifteen hundred feet. 
 Ice of this thickness would rest on the beds of all the shallower friths and 
 seas, and act upon them precisely as upon the rocky surfaces of the dry 
 land. This circumstance should be carefully borne in mind in reasoning 
 on the phenomena of the glacial epoch. 
 
236 THE GLACIAL OR ICE EPOCH. 
 
 second stage of the glacial epoch, and must have been 
 characterised "by all that glacier on land or iceberg on water 
 are capable of performing. The ice-sheet that now gathered 
 over the gradually -decreasing land would push its way 
 shoreward with its annual burden of debris, and this de- 
 bris, as it was carried seaward, would be dropt in part over 
 the clay, shingle, and boulders that had been accumulated 
 during the first stage. Of course, a considerable portion of 
 the debris of the first stage would be removed by shore 
 denudation as the land subsided, but a large portion was 
 also left undisturbed ; and thus it is that we find in many 
 places the earlier clays and angular blocks covered over by 
 other clays, replete with boulders more worn and rounded, 
 and more strongly marked by scratches and furrows. It 
 was then, and during this period of subsidence, that huge 
 boulders were carried by floating ice far from their parent 
 rocks ; and thus it is that these boulders, now hundreds of 
 miles from their original cliffs, mark in a special manner 
 the second stage of the glacial epoch.* During this stage, 
 as during the preceding, we have no evidence of a terres- 
 trial flora or fauna, the climate being evidently too rigorous 
 for their support ; and it is only towards the southern 
 limits of the ice-field (the 40th or 42d parallel of lati- 
 tude t) that we can expect to find the remains either of 
 
 * It is difficult to convey by description the difference between the 
 clays and boulders of the first and second stages ; but a few days in the 
 field will train the eye sufficiently to mark the distinction, and this 
 altogether independent of superposition. There is a roughness of ad- 
 mixture and heterogeneousness about them that never appear in those 
 of the earlier stage. Perhaps the best test of the second stage is the 
 number of " erratic blocks," or boulders far removed from their parent 
 rocks. In Europe, Scandinavian rocks are found in Central Germany 
 and over the south-east of England ; in North America, Canadian blocks 
 occur a hundred and a hundred and fifty miles southward of their 
 parent sources. 
 
 t American geologists give the southern limit of the drift in their 
 
ITS THIRD STAGE. 237 
 
 plants or animals, and these in all likelihood of "boreal 
 habits, like those now inhabiting the borders of the arctic 
 regions. How long this period of descent continued rela- 
 tively to the other stages, it is difficult to determine, 
 though, on the whole, it appears to have been the longest 
 stage, and that which has most impressed its character on 
 the terrestrial surface. The extent to which the subsi- 
 dence took place is variously estimated at from 1700 to 
 2000 feet, for from that limit down to the existing sea- 
 shore, the land-surface is marked with rounding and smooth- 
 ing, polishing and scratching, glacial moraines and clays, 
 ice- borne blocks and boulders. One cannot turn to the 
 higher districts of our own islands, to the north of Europe, 
 or to Xorthern America, without perceiving on every hand 
 traces of this long-continued ice-action the bouldery clays, 
 the rounded blocks and boulders, the scratched and polished 
 rock-surfaces, the rounded outlines of the hills and knolls, 
 all bespeaking its presence as incontestably as the existing 
 surface of the Alps, the Scandinavian mountains, or the 
 uplands and shores of Greenland. 
 
 But the forces that govern the external conditions of our 
 planet are never at rest. Change succeeds change, and cycle 
 follows cycle. The downward tendency of the land ceases, 
 and an upward movement commences. Along with this 
 gradual elevation, new distributions of sea and land begin 
 to appear, and with these changes the intensity of the gla- 
 cial epoch seems to come to a close. Glacier and ice-sheet, 
 however, still shroud the land, and icebergs drift away 
 from the shores. Other currents, however, are evidently 
 setting in, a more genial climate begins to prevail, and with 
 this higher temperature the ice disappears frum the seas 
 and lower grounds, and only clings to the higher bills in 
 
 continent as 39 N. lat. ; in Europe it has been variously stated at 40, 
 42% and even 44 N. lat. 
 
238 THE GLACIAL OR ICE EPOCH. 
 
 shrinking and gradually lessening glaciers. Even these, 
 too, vanish in the long-run, and the present order of things, 
 the ordainings of the current epoch, are established. This 
 gradual elevation of the land constitutes the third and last 
 stage of the glacial epoch, the proofs of which are to be 
 found in the moraines, lateral and terminal, that still linger 
 in every glen and corrie of our island, in the re-assorted 
 clays and boulders of the two former stages, in the numerous 
 terraces which mark the successive steps of the land's up- 
 rise, and in the fine silty clays (the " brick-clays " of some 
 geologists), with boreal shells, star-fishes, bones of seals 
 and whales, which fringe our bays and estuaries at various 
 altitudes above the present sea-level. Compared with the 
 earlier stages of the ice-epoch, the traces of this latter stage 
 are still fresh and recent. The mounds of sand and gravel 
 so frequent at the mouths of all. our glens and upland 
 valleys, are but the terminal moraines of the ancient gla- 
 ciers ; the gravelly terraces (in some instances with shells) 
 that fringe so many of our hill-sides, are but the ancient 
 beaches of the gradually uprising land ; the great blocks and 
 boulders so abundantly strewn over our heathy uplands, 
 are but the denuded ice-borne blocks of the two former 
 stages ; and the fine silty " brick-clays " are but the up- 
 raised muds of the deeper sea-bed. Since then, frost, rain, 
 and rivers have done their work on the land's surface, and 
 obliterated many of the ice-traces, yet enough still remains 
 to convince the unbiassed inquirer of its long reign over 
 these northern latitudes during the three successive stages 
 we have here endeavoured to describe. 
 
 The accumulations described in the preceding paragraphs 
 are usually distinguished by such names as " northern 
 drift," " glacial drift," " erratic blocks," and " boulder- 
 clay," all conveying the idea that they have not been de- 
 
PROOFS OF ITS EXISTENCE. 239 
 
 posited under the ordinary conditions of water, that they 
 belong especially to the northern hemisphere, have been 
 drifted from a northerly source, and in all likelihood by 
 ice partly on land and partly in water.* The older terms 
 " diluvium " and " diluvial drift," under the idea that they 
 were the results of the Noachian deluge, have been long 
 ago set aside, and geologists with one consent now look to 
 ice, in one or other of its manifestations, as the only known 
 agent by which they could have been accumulated. Eain 
 and rivers can, no doubt, waste and wear down the land, 
 but it is ice alone that can grind and smooth and confer 
 those rounded outlines which characterise so much of the 
 surface in the higher latitudes of the northern hemisphere. 
 River floods and freshets can accumulate vast mounds of 
 sand and shingle ; but it is the glacier alone that throws 
 across the glen its dam-like moraine, and scores and polishes 
 the pebbles of which it is composed. Running water laden 
 with debris will wear and smooth the rock-surfaces over 
 which it flows ; but it is ice alone that can put on the glassy 
 polish, and scratch and gouge in long straight furrows with 
 its imbedded blocks and fragments. Rivers and torrents 
 will roll and transport blocks of considerable size ; but it is 
 ice alone, either as the ice-sheet on land or the iceberg on 
 water, that can tansport boulders many tons in weight up 
 and over hills, or float them away hundreds of miles from 
 their parent precipices. Running water invariably assorts 
 its debris in beds and layers according to its fineness ; it is 
 floating ice alone that drops its burden on the sea-bed with- 
 out regard to arrangement. All these appearances boulder- 
 
 * Objection has been taken to each and all of these designations, and 
 it must be confessed we are still in want of a good general term for the 
 accumulations of the glacial epoch. Drifts, erratic blocks, and boulder- 
 clays, are but members of a great series, and it is for this series, taken 
 as a whole, that we still stand in need of a comprehensive designation. 
 
240 THE GLACIAL OR ICE EPOCH. 
 
 clays of great thickness, erratic Hocks of enormous size, 
 polished, striated, and grooved rocks, moraine-like mounds 
 of gravel, and smoothed and rounded surfaces are so com- 
 mon in Britain, Northern Europe, and North America, 
 that geologists are driven to the conclusion of a glacial 
 epoch; a long period intermediate between the Tertiary 
 and the Current era, when all the northern hemisphere, 
 down to the 40th or 42d parallel, was under the influences 
 of an icy climate like that which now prevails within the 
 arctic and antarctic circles. 
 
 Geologists have long been at variance, and in some in- 
 stances are still at variance, as to whether the phenomena 
 are to be attributed more to land-ice or to sea-ice, to glaciers 
 or to icebergs. As we became better acquainted, however, 
 with the operations of ice in such regions as the Alps, 
 Himalayas, Scandinavia, Spitzbergen, Greenland, and the 
 polar seas, such differences of opinion grew less, and com- 
 petent authorities seem to be agreed that we must call in 
 both agencies, and this during the successive stages of sub- 
 sidence and re-elevation which we have already endeavoured 
 to describe. Indeed, it is impossible to conceive of a glacial 
 climate over any large portion of the earth's surface without 
 seeing that it must affect sea and land alike j and that if 
 there is any brief period of thaw, like the existing arctic 
 summer, the ice must be set in motion both on land and 
 water.* Once set in motion, each would contribute its 
 quota to the general result the land-ice grinding and 
 smoothing and rounding the rocky surface in its descent to 
 the sea, and the sea-ice ploughing the shallower sea-bed as 
 it floated away to drop its burden of boulders and debris 
 
 * Even without any great degree of summer thaw, a mobile mass like 
 ice and snow would be urged forward by its own accumulating weight, 
 and this over heights and hollows, so long as the head pressure remained 
 sufficiently powerful. See preceding Sketch, p. 221. 
 
DIRECTION OF ITS DRIFTS. 241 
 
 in the deeper and warmer waters. In consequence of the 
 long subsidence and gradual re-elevation of the land, the 
 results of the terrestrial and sea-floated ice would become 
 commingled ; and hence one great source of the difficulty 
 attending the interpretation of the phenomena of the glacial 
 epoch. He, therefore, that would read aright the ice-epoch, 
 must restrict himself to no limited theory, but must grasp 
 broadly the consequences of a general glacialised condition, 
 calling in alike the aid of terrestrial and marine ice, and 
 ascribing to both what he cannot clearly determine as 
 having been performed by either. 
 
 Another question that has given rise to much discussion, 
 is the direction in which the ice has generally moved, and 
 the source or sources from which the debris has been borne. 
 In the north of Europe the set seems to have been from 
 the north or a little west of north, so that the rocks torn 
 from the Scandinavian mountains have been scattered over 
 the plains of Denmark and Germany. In the British 
 Islands, the set seems also to have been from the north and 
 north-west, so that boulders from the Grampians are strewn 
 over the Lowlands, and blocks from the Cumberland hills 
 over the valleys of Yorkshire. In North America too, the 
 general float or trend has been, in like manner, from the 
 north, or from directions between the north and north-west 
 hence the appropriateness of the term " northern drift " 
 when applied to the erratic blocks that now lie scattered so 
 far and wide from their native sources. But in most coun- 
 tries the land-ice has moved in accordance with the general 
 slopes of the land or the trends of its principal valleys ; 
 hence the glacial gougings and groovings radiate in all 
 directions from some main eminence, or lie chiefly in one 
 way, according to the bearing of the valley down which the 
 ice has descended. A great deal of minute but worthless 
 labour has indeed been spent on this subject. The grooves 
 
 Q 
 
242 THE GLACIAL OE ICE EPOCH. 
 
 and strise produced by the mountain-glacier can give no 
 idea of the direction of the current that bore the iceberg ; 
 and the ploughings of the iceberg through firth and strait 
 can give no indication of the course of the glacier from 
 which it was detached. The fact is, that the direction of 
 these groovings and gougings must be read each in the light 
 of its own locality ; and we have seen on many rock-sur- 
 faces in Scotland striae crossing each other, and evidently 
 produced at different times by forces moving in different 
 directions. That the land-ice must have moved in the 
 direction of the slopes on which it rested, is self-evident; 
 and that the floating ice must have taken a southerly course, 
 is only what may have been expected, seeing that the cold 
 currents from the poles must ever be towards the warmer 
 and lighter waters of the equator. 
 
 A third and important question is, whether this glaciation 
 of so large a portion, of the northern hemisphere was con- 
 temporaneous, or whether it passed gradually and succes- 
 sively over the areas of Europe, Asia, and America ? This 
 question, in fact, involves the cause of the glaciation, and 
 will be answered very mu(jh according to the views which 
 different theorists entertain. If we regard the ice-epoch as 
 brought about by external or astronomical causes, its con- 
 temporaneity is the most likely result ; but if we consider 
 it as arising from some peculiar distribution of sea and land, 
 and dependent on the earth's own physical relations, the 
 glaciation of Europe may have been separated by long ages 
 from that of America ; or, in other words, the ice-mantle 
 may have gradually crept from the one hemisphere to the 
 other, according as the set of polar currents was altered by 
 upheaval and depression of the land areas. In the mean 
 time, the general leaning seems to be towards the idea of 
 contemporaneity, though it must be confessed that a gradual 
 advance of the glaciation from area to area seems, in some 
 
SUPPOSED CAUSES OP. 243 
 
 respects, the more philosophical belief. Either way the 
 fact remains of its occurrence between the tertiary and cur- 
 rent epochs ; of its having brought to a close the tertiary 
 conditions that prevailed over these latitudes; and of its 
 having passed away before the present order of things 
 could be established. Wherever it occurs it forms a great 
 hiatus between the Tertiary and Recent a lifeless blank, 
 as it were, between the flora and fauna of the Tertiary epoch, 
 and the flora and fauna now flourishing around us. 
 
 The hypotheses that have been advanced to account for the 
 glacial epoch resolve themselves into two great categories 
 first, those that depend on astronomical causes, or causes 
 extraneous to the earth ; and, second, those that depend on 
 the earth's own physical relations as regards the then pecu- 
 liar distribution of its lands and waters. This is not the 
 place to enter minutely into the merit of these theories, 
 but we may glance at their general bearings as indicating 
 the widely different sources to which geologists have been 
 driven for a solution of this strange and anomalous period. 
 By those who seek for the solution in a peculiar distribution 
 of sea and land, it is argued, that by elevating the terres- 
 trial surface in the northern hemisphere and shutting oif 
 the warm currents of the ocean from the circumpolar areas, 
 an extreme degree of cold would be induced; that the snow 
 and ice accumulated under this cold would have a tendency 
 to diminish still further the annual temperature ; and that 
 by these means the ice-sheet, in course of ages, would push 
 its way southward alike over land and sea, to the furthest 
 known verge of glaciation. This, they contend, would 
 account for the first stage of the ice-epoch : and even when, 
 during the second stage, the land began in some areas to 
 subside, the ice-sheet must have acquired so much mastery 
 over the average annual temperature as still to maintain its 
 
244 THE GLACIAL OR ICE EPOCH. 
 
 ground the chief heat conveyed to the north being by- 
 atmospheric currents. During the third stage, when the 
 land began to rise, the elevation, they argue, was only 
 partial, and accompanied by depressions, which permitted 
 warm oceanic currents to penetrate further north, and thus 
 gradually to dissolve the ice -sheet to its present limits. 
 Others also, who seek for the solution in the peculiar dis- 
 tribution of sea and land, contend that the ice-mantle was 
 never general over the northern hemisphere, but that it 
 passed from area to area according to the set and direction 
 of the polar sea-currents. Were the existing arctic current, 
 say they, to pass down by the coasts of Norway instead of 
 by the coasts of Labrador, the glaciers of Scandinavia would 
 envelop the whole peninsula, and come down, as they do 
 in Spitzbergen, to the very sea-shore. It is only necessary, 
 these theorists contend, to arrange the polar currents and the 
 warm currents (like the Gulf Stream), or, in other words, the 
 northward and southward currents of the ocean, in such a 
 way as to produce over certain areas glaciers and icebergs, 
 and all the accompanying phenomena of the glacial epoch. 
 
 Those, on the other hand, who appeal to extraneous causes, 
 maintain that the ice-sheet was general and contempor- 
 aneous, and could only be produced by forces affecting alike 
 the whole of the northern hemisphere. In their opinion, 
 there was only a gradual advance, and as gradual a departure, 
 of the ice- epoch. And this advance and departure may 
 have been brought about by our planetary system passing 
 through some colder region of space ; by some secular or 
 recurrent diminution of the sun's heat; by greater eccen- 
 tricity of the earth's orbit; or by some secular deviation 
 in the earth's inclination, depending upon change of centre 
 of gravity, or the precession of the equinoxes. In other 
 words, the causes they seek to establish are planetary 
 and not terraqueous, and such as have already occurred, 
 
SUPPOSED CAUSES OF. 245 
 
 and will yet occur, in the history of our globe. Of course, 
 before such hypotheses can be entertained, astronomers 
 must admit their possibility, and find in the existing 
 ordainings of nature some proofs that such great periodic 
 changes are still in process of fulfilment. It is true that 
 we are not without evidence of colder and warmer periods 
 over the same latitudes in the geological history of our 
 planet. It is many years ago * since we first drew attention 
 to the occurrence of colder and warmer cycles the Cam- 
 brian, Old Red, Permian, Cretaceous, and Boulder- Drift, 
 being the cold, and the Silurian, Carboniferous, Oolitic, 
 Tertiary, and Recent, being the warm ; but we still need 
 further corroboration of this, and it were the wisdom of 
 geology to exhaust the operative causes that lie within our 
 knowledge in the earth before seeking for extraneous causes 
 that are placed in the mean time beyond our probation. In 
 either case we cannot conceive of colder and warmer cycles 
 occurring at random ; and whether they depend upon the 
 earth's own ordainings, or upon her wider planetary re- 
 lations, they must be obedient to an orderly law of time, 
 and will occur in the future as they have already taken 
 place in the past. 
 
 Of course, before the origin and history of the glacial 
 epoch can be fully expounded, much exact and prolonged 
 labour must be devoted to the subject. The sequence and 
 superposition of the clays, gravels, boulders, and silts, re- 
 quire more thorough examination over wider areas than 
 those of the British Islands. The southerly limits of these 
 accumulations in Europe, Asia, and America require to be 
 determined with greater precision ; as well as the question 
 of their altitude, and their dispersion over eastern and 
 central Asia. We have also to learn how far the southern 
 hemisphere (in Patagonia, Australia, and New Zealand) has 
 * See ' The Past and Present Life of the Globe/ p. 189-191. 
 
246 THE GLACIAL OR ICE EPOCH. 
 
 ever undergone a similar glaciation; and if so, whether 
 it took place, as in the northern hemisphere, immediately 
 preceding the current era.* These and similar questions 
 must receive satisfactory answers hefore a generally ap- 
 proved theory can he hoped for; and geology, in this as 
 in other instances, will "best attain her end "by a diligent 
 accumulation of facts, and the widening of her field of 
 observation. 
 
 Such is a hasty, hut, we trust, not unintelligible Sketch 
 of the glacial or ice epoch that strange period in recent 
 geology when the frost-giant that now reigns supreme within 
 the polar circles laid his iron grasp on the northern hemi- 
 sphere down to the 40th or 42d parallel of latitude. How 
 or by what means this crisis was brought about whether 
 by some peculiar distribution of sea and land, or by some 
 great secular recurrence in the earth's planetary relations 
 theorists are not agreed; but there is no difference of 
 opinion as to its existence, and none as to the long con- 
 tinuance of its sway. Its presence is visible on every hill- 
 side and in every glen in the British Islands, Northern 
 Europe, and North America ; in the rounded eminences, in 
 the polished and striated and grooved rock-surfaces, in the 
 moraine-like mounds of gravel that bar the glens, in the 
 huge rounded and striated blocks that lie scattered over the 
 ground, and in the thick tenacious bouldery clay that en- 
 velops so much of the lower and level tracts of the country. 
 No known agent, save ice, could have produced these ap- 
 pearances ice on land, and ice on water ; ice, in fact, such 
 
 * From recent reports by the provincial surveyors of New Zealand, as 
 well as from Mr Darwin's well-known descriptions of South America, it 
 would appear that the southern hemisphere has been subjected to a simi- 
 lar phase of ice-action. The further investigation of this as to contempo- 
 raneity with that of the northern hemisphere, would materially assist in 
 the framing of an acceptable hypothesis. 
 
GENERAL REVIEW. 247 
 
 as we now behold on the higher mountains of the globe, 
 and within the arctic and antarctic regions. 
 
 "We have arranged the period into three stages the first, 
 when the pre-glacial land (somewhat higher than the exist- 
 ing continents) began to receive the ice-sheet ; the second, 
 during which the ice-bound land subsided to the extent of 
 1800 or 2000 feet; and the third, during which the land 
 was step by step re-elevated, and the ice gradually dis- 
 appeared.* Each of these three stages must have left its 
 own proper impress ; but the second has obliterated so 
 much of the first, and the third so much of both, to say 
 nothing of what has been subsequently effaced by frosts 
 and rains and rivers, that it is always extremely difficult, 
 and often impossible, to discriminate their results. Hence 
 the great difficulty of reading aright the phenomena of the 
 glacial epoch ; and hence the conflicting views entertained 
 by geologists respecting their origin and arrangement. This 
 much, however, is certain, that the pre-glacial or pliocene 
 land -surfaces, wherever they are found, contain fossils; 
 that the first stage of the ice-epoch is characterised by 
 boulders little removed from their parent rocks, by finely 
 glacialised rock-surfaces, and by the true boulder-clay or 
 " till " of Scottish geologists, and is always unfossiliferous ; 
 that the second stage is characterised by re-assorted clays, 
 by more rounded and widely-dispersed boulders, and is also 
 
 * While, for the sake of distinctness, we thus divide the ice-epoch 
 into three great stages, it must be borne in mind that there may have 
 been minor and local osciDations of sea and land during each successive 
 stage. Since the close of the glacial period such oscillations have taken 
 place more than once in our own islands, as proved by the " submarine 
 forests " that occur at so many places along the existing coasts these 
 forests, now partially under the sea-level, having evidently grown at a 
 higher elevation, been submerged to receive the silts that now cover 
 them, and again upraised to their present levels. Such minor oscilla- 
 tions tend to complicate, but they do not obliterate, the broader pheno- 
 mena of a period. 
 
248 THE GLACIAL OR ICE EPOCH. 
 
 unfossiliferous ; while the third stage has more moraines, 
 ridges of sand and gravel, terraces with occasional shells, 
 and finally, in the lower levels, the silty clay or " brick-clay," 
 containing boreal shells, star-fishes, bones of seal, whale, 
 northern ducks, and other kindred remains. The local 
 differences may not be always ascertainable ; the general 
 order above sketched is unmistakable throughout the 
 British Islands. 
 
 Cold and dreary, and inimical to life, as the ice-epoch 
 must have been, it has left its impress on every foot of the 
 surface to which its limits extended. The rounded outlines 
 of our hills, the gentler mouldings of our glens, the scoop- 
 ing-out of many of our higher lake-basins, the undulating 
 gravelly surfaces of our broader valleys, the terraciform 
 southern and south-eastern slopes of our mountains nine- 
 tenths, in fact, of that which gives character and colour to 
 our northern scenery are the direct results of its long-con- 
 tinued sway. Much has no doubt been since obliterated 
 by the frosts, rains, and running waters of the current era, 
 but the broader features chiselled out by the ice-epoch still 
 remain, reminding the spectator at every turn of its pre- 
 sence, and the long continuance of its power. 
 
EECEKT FOEMATIONS. 
 
 RECENT OR POST-TERTIARY FORMATIONS LATEST CHAPTER IN GEO- 
 LOGICAL HISTORY FLUVIATILE : DALES AND RIVER-TERRACES 
 LACUSTRINE : ALLUVIAL FLATS AND STRATHS ESTUARINE : PLAINS 
 AND DELTAS MARINE : SILTS, SAND-DRIFTS, AND RAISED BEACHES 
 CHEMICAL : MINERAL PRECIPITATES AND EXUDATIONS OR- 
 GANIC ! VEGETABLE AND ANIMAL GROWTHS VOLCANIC : LAVAS, 
 TUFAS, ETC. EXTENT AND VARIETY OF RECENT FORMATIONS 
 THEIR STUDY THE KEY TO THOSE OF EARLIER DATES CHRONOLO- 
 GICAL ARRANGEMENT OF HISTORIC AND PRE-HISTORIC HUMAN 
 AND PRE-HUMAN. 
 
 As the glacial epoch, with its bouldery clays and gravels, 
 formed a limit to the tertiary system over a large portion 
 of the northern hemisphere at least so within the same 
 latitudes it constitutes an equally decided basement for 
 what are usually termed the Post-tertiary, or recent forma- 
 tions. Of course, like other appellations in geology having 
 reference to time, these terms are merely relative, embracing 
 accumulations that have taken place within the current 
 century, and others that may have been formed fifty or a 
 hundred thousand years ago, but still recent when compared 
 with those of the tertiary and other preceding systems. 
 This is all that is meant by the title at the head of the 
 present Sketch ; and whether we adopt Quaternary, Post- 
 tertiary, or Eecent designations all employed by geologists 
 in describing these formations it matters little so long as it 
 is understood that the events referred to have taken place 
 subsequent to the glacial era. These events, recent though 
 
250 RECENT FORMATIONS. 
 
 they be, present a curious but difficult chapter in world- 
 history; curious as displaying more clearly than the older 
 formations their whole origin and progress, but, like modern 
 human history, difficult of narration, from the exuberance 
 and nearness of the details. Approaching our own times, 
 their interest is proportionally increased, and he who under- 
 stands them aright cannot fail to catch by reflection a clearer 
 insight into the cycles and systems that went before. In 
 their origin and formation we see a repetition of the origin 
 and formation of all the older formations, hence their in- 
 structiveness as a study ; while in their superficial disper- 
 sion they become the immediate source of sustentation to 
 the plants and animals that inhabit the terrestrial surface. 
 
 Arising from the operations of waste and reconstruction 
 described in Sketch No. 2, these Eecent, or, as they are 
 sometimes termed, Superficial Accumulations, will be as 
 multifarious as the agencies concerned in their formation ; 
 and hence perhaps the most intelligible way of treating 
 them is to. arrange them according to the agents more im- 
 mediately concerned in their production. In this way we 
 will have Fluviatile formations, or those arising from the ac- 
 tion of rivers ; Lacustrine, or those formed in lakes ; Estua- 
 rine, in estuaries; Marine, in seas; Chemical, arising from 
 chemical action; Organic, from the growth and decay of 
 plants and animals ; and Volcanic, from the internal fire- 
 forces of the globe. There will be older and younger, of 
 course, among these different formations some so old as to 
 imbed the remains of plants and animals no longer inhabiting 
 the same localities, and others so recent as to belong entirely 
 to the current age, and indeed to be still in process of forma- 
 tion. To display them, whatever their age, in intelligible 
 order, is the object of the present Sketch ; and he who bears 
 in mind the operations of waste and reconstruction de- 
 scribed in a previous paper, can have no difficulty in fol- 
 
FLUVIATILE. 251 
 
 lowing the narration of this, the most recent chapter in 
 geological history. 
 
 Among the most obvious of Eecent Formations are those 
 produced by the action of rain and rivers. Whatever the 
 winds and rains and frosts loosen and disintegrate, the 
 stream carries onward and downward to lower levels. 
 Were there no great rivers, the debris worn from the moun- 
 tains would accumulate mainly along their bases, but the 
 runnels gave it to the streams, the streams by their union to 
 the river, and the river carries it forward to be scattered over 
 the plains, to be deposited in lakes, or borne out to the 
 depths of the ocean. Geologically speaking, what is strictly 
 Fluviatile is laid down by the streams and rivers along their 
 courses ; and there is not a river in the world that does not 
 present, in some portion or other of its course, patches of 
 meadow-land, holmes, dales, and other flats, that have been 
 formed by the debris carried down by its current. These 
 alluvial flats are generally very heterogeneous in their com- 
 position loamy and clayey silts, sand, gravel, and shingle, 
 with here and there the imbedded but often imperfectly 
 preserved remains of terrestrial plants and animals. In 
 course of ages, as the river deepens its channel, and cuts its 
 way from side to side down the valley, the older of these 
 flats will stand higher and higher above the current ; and 
 thus it is that along most rivers there are sets of terraces 
 marking the heights at which they formerly ran, and the 
 levels over which they spread their inundating waters. It 
 is usual to arrange these terraces into higher river-gravels 
 and lower river-gravels the former of vast antiquity, and 
 rarely containing organic remains, and the lower of more 
 recent origin) and containing the remains of plants and 
 animals, some of which have long since become extinct in 
 the regions where their relics now occur. It is from the 
 
252 RECENT FORMATIONS. 
 
 lower and middle of these terraces in Britain, Trance, and 
 other European countries, that the bones of the mammoth 
 and woolly rhinoceros have "been exhumed, along with the 
 flint implements of rude and primitive races ; and were the 
 river-deposits of the other continents geologically examined, 
 there is no doubt they would exhibit in a similar way a gra- 
 dation from the events of the current century back to those 
 bordering on the tertiary epoch. As it is, these river-deposits 
 play an important part in the physical geography of every 
 country, their rich and well- watered surfaces presenting the 
 finest fields, whether for forest-growth, pasture, or cultivation. 
 We have only to name the principal rivers of the world to 
 recall to the geographical reader the alluvial expanses that 
 mark the most of their courses, and these in magnitude 
 according to the volumes of the respective rivers and the 
 flatness of the country through which they flow. And 
 even where magnitude is not concerned, these river-deposits 
 are not without their importance. Every gully from the 
 mountain-side has its. terminal spit of sand and gravel, 
 and it is often in such deposits, worn from the cliffs and 
 veins above, that we find the most abundant and readiest 
 supplies of the gems and precious metals as witness the 
 diamond-conglomerates of Brazil and India, the tin-gravels 
 of Cornwall, and the gold-sands and shingle of California, 
 Columbia, Australia, New Zealand, and the Oural. These 
 auriferous sands and gravels are but the debris of the older 
 mountain-cliffs disintegrated by the frosts and rains, and 
 carried down by the streams to the lower " creeks " and 
 "gullies," where, accumulating for ages, they are often of 
 great thickness, and carry us, in many instances, far back 
 even into the tertiary period. Many of the Australian 
 gold-gravels, indeed, are surmounted by thick overflows of 
 basaltic lava, and as volcanic agency has long ago ceased to 
 manifest itself in these regions, these show at once the vast 
 
LACUSTRINE. 
 
 253 
 
 changes that must have taken place, and the ages that must 
 have elapsed since the gravels and sands were piecemeal 
 worn and washed down from their parent formations.* 
 
 Closely associated with these river- deposits, and some- 
 times indeed undistinguishahle from them, are the Lacus- 
 trine or lake deposits, that occupy so many of the alluvial 
 expanses in our plains and valleys. The tendency of 
 every lake fed by running streams is to become shallower 
 and shallower from the sediment deposited in its basin by 
 these inflowing waters. Every stream protrudes its little 
 delta of silt and sand, fresh-water shell-fish accumulate 
 layers of marl, and aquatic plants contribute their annual 
 quota of growth and decay. By-and-by the shallow lake 
 becomes a stagnant morass, and in process of time, partly 
 by surface plant- growth, and partly by the deepening of the 
 outflowing stream, the morass is converted into meadow- 
 land. A large portion of all the " straths " of Scotland 
 and the "dales" of England are of lacustrine formation; 
 and we have only to watch the cutting of any main drain 
 
 * The following is a section of the Uralla gold-field, as given to us some 
 years ago by Mr W. Cleghorn of that district : 
 
 Red rich soil, . . 5 feet. 
 
 Stiff red clay, . 5 
 
 Mottled clay volcanic ashes . 20 
 
 Basaltic lava, . . 35 
 
 Brown laminated clay, . 5 
 
 Loose sand (decomposed quartz and granite) . 2^ 
 
 Black peaty clay, with numerous leaves and stems, 6g 
 
 Loose sand (decomposed quartz and granite) . 2 
 
 Finely laminated reddish clay, . 1 
 Loose sand (decomposed quartz and granite), with 
 
 numerous crystal-pebbles and a little gold, . 15 
 
 Fine reddish clay, . . . . . 
 Loose sand (decomposed quartz and granite), with 
 
 numerous pebbles the main gold deposit, . 4 
 
 102 
 
 Granite, water- worn surface, with large granitic boulders. 
 
254 EECENT FORMATIONS. 
 
 through their subsoils to be convinced of the truth of this 
 origin. A thick layer of vegetable or peaty soil, followed 
 by beds of silty sand, marl, and clay, imbedding the bones 
 of deer, oxen, and other animals, with the remains of an 
 occasional tree-canoe, clearly bespeak their lacustrine forma- 
 tion, and point to the time when the wild animals of the 
 country were mired in their muds, and the primitive inhabit- 
 ants paddled across their waters. JSTow how changed ! the 
 site of the former lake green with the richest pastures, or 
 waving with luxuriant corn-fields ! As with the straths and 
 dales of Britain, so with a large proportion of all the inland 
 plains and valleys of the world. Many of them are but 
 chains of silted-up lakes converted into dry land, partly by 
 the process of silting or filling up, and partly by the main 
 stream of the valley cutting deeper and deeper its channel, 
 and thus affording a more thorough drainage for the whole. 
 Lacustrine formations, though occurring in the same plain 
 with those of fluviatile origin, are in general readily dis- 
 tinguishable by their finer sediments, greater regularity of 
 deposition, the occurrence of beds of shell-marl and peat, 
 and the more perfect preservation of their organic remains. 
 These remains are often of great antiquity, ranging from 
 the time of the mammoth, great Irish deer, and species of 
 oxen that have been long extinct, down to the pile-dwellings 
 of our Celtic or pre-Celtic ancestors, who betook themselves 
 for safety to their waters, and erected artificial mounds for 
 their habitations, where nature had not provided the neces- 
 sary "inches" or islands.* Even since the time ^of the 
 
 * Since 1854 these lake-dwellings or pile-dwellings (known as pfahl- 
 ^iten in Switzerland, and crannoges in Ireland), have received much 
 attention from archaeologists and geologists. These dwellings occur in 
 existing lakes, as well as in bogs and marshes which were formerly the 
 sites of lakes, and seem to have been erected on piles driven through 
 the water, or on mounds partly formed of stones, wood, and other 
 debris. They have been found in Switzerland, Ireland, Scotland, and 
 
ESTUARINE. 255 
 
 earlier Celts hundreds of shallow lakes and morasses have 
 been converted into dry land ; and the process still goes 
 forward, accelerated in all civilised countries by the inces- 
 sant operations of man. 
 
 Still associated with river-action, but necessarily separated 
 from strictly fluviatile deposits, are those Estuarine forma- 
 tions which occupy extensive areas in almost every region 
 of the globe. Wherever a river discharges itself into the 
 sea by a broad mouth, or by many mouths, and in particular 
 where the tidal influence pounds back the river- water and 
 runs for some distance inland, sandbanks and mud-shoals 
 have a tendency to accumulate. In process of time the 
 banks and shoals become islands, and by further accretion 
 and union the islands are converted into deltas. In this 
 way most of our larger rivers present deltic flats or estua- 
 rine formations, and these must have been slowly accumu- 
 lating since sea and land received their present relative 
 configurations. These accumulations, consisting mainly of 
 debris borne down by the river, but partly also of tidal 
 sediments, will imbed marine as well as terrestrial and 
 
 other European countries, and point to a time when the early inhabitants 
 "betook themselves to this style of habitation for purposes of defence and 
 protection. In some instances, as in the Swiss lakes, the piled area is 
 of considerable extent (forming an aquatic village, as it were), and con- 
 nected with the shore by a piled way or causeway. In the older pfahl- 
 bauten the implements are chiefly of stone, and associated with the cast- 
 away bones of the deer, boar, and wild-ox ; in those of intermediate age, 
 bronze implements prevail, associated with the bones of the domestic ox, 
 pig, and goat ; while in the more recent, iron swords and spears have 
 been found, accompanied by carbonised grains of wheat and barley, and 
 with fragments of rude textures woven of flax, bast, and straw. The 
 more recent seem to have been immediately anterior to the great Roman 
 invasion of northern Europe ; the more ancient may be several thousand 
 years older than that event. Those curious in these matters may consult 
 Dr Keller's ' Lake-Dwellings of Switzerland,' as translated and arranged 
 by Mr Lee, 1866. 
 
256 RECENT FORMATIONS. 
 
 fresh-water organisms, and thus they are regarded as estu- 
 arine or fluvio- marine, in contradistinction to those of 
 strictly fluviatile or lacustrine origin. The low-lying deltas 
 of the Mississippi, the plain of Lower Egypt, the jungle- 
 swamps of the Niger, the sunderbunds or mud-islands of 
 the Ganges and Irawaddy, and the alluvial plain of China, 
 are familiar examples on a great scale of these estuarine or 
 deltic deposits; "but as with these, so with almost every 
 other river that discharges its waters into the ocean. The 
 magnitude of estuarine formations is one of the most 
 notable features in the geology of the current epoch, and 
 this magnitude is increased by a twofold process which the 
 reader would do well to consider. 
 
 In the first place, the delta that makes its appearance as 
 dry land may form but a small portion of the sedimentary- 
 matter borne down by a river, the greater portion being 
 carried forward and projected, as it were, over the bed of 
 the ocean. An estuarine formation is thus partly sub- 
 aerial and partly submarine, and it necessarily requires a 
 long and gradual process of silting to convert the sub- 
 marine into sub -aerial. But during the oscillations or 
 crust-motions to which the earth is subjected, it frequently 
 happens that a whole island or portion of a continent is 
 gradually upraised, and thus the submarine portion of an 
 estuary may be upheaved into dry land, and this altogether 
 independent of the slow and ordinary process of silting. 
 An uprise of fifty feet would convert a large portion of 
 the Yellow Sea into a lower terrace of the great Chinese 
 plain ; and by a similar uprise thousands of square miles 
 of Mississippi swamp would assume the character of fertile 
 prairie-ground. To such upheavals much of the " carses " 
 of Scotland and " levels " of England are no doubt due ; 
 for though wholly composed of river and marine silts, their 
 final conversion into dry alluvial plains has been more a 
 
ESTUARINE. 257 
 
 matter of terrestrial uprise than of sedimentary accumula- 
 tion. As with the estuarine plains of our own islands, so 
 to a great extent with those of other regions : they owe 
 their accumulation wholly to silt and sediment, "but their 
 conversion into dry land, partly to silting, and partly to 
 terrestrial upheavals. 
 
 Whatever their mode of accretion, the composition of 
 these estuarine formations is much the same in every 
 region : mud -silts, clays, sands, gravels, drift-wood, shell- 
 beds, peat and swamp earths the whole being usually 
 surmounted by loamy, vegetable soils of extraordinary fer- 
 tility. Their imbedded remains are partly terrestrial, partly 
 fresh-water, and partly marine ; and these, of course, will 
 differ according to the latitudes in which the estuary occurs, 
 and the regions through which its affluent rivers flow. 
 Thus the Mississippi will sweep down the terrestrial and 
 fresh- water spoils of temperate North America, the Amazon 
 those of tropical South America, the Niger those of Equa- 
 torial Africa, and the Ganges and Irawaddy those of sub- 
 tropical Asia. Every estuary, in fact, is characterised by 
 its own fossil flora and fauna, and these of varying anti- 
 quity, from the spoils swept down by the latest land-flood 
 or deposited by yesterday's tide, back to the confines of the 
 glacial epoch, if in the higher latitudes, and it may be to 
 the tertiary itself, if occurring in intertropical regions. In 
 the estuarine silts of our own islands, for example, we pass 
 through every gradation of antiquity, from the plants and 
 animals now flourishing around us, back through those 
 which, like the bear, wild-boar, wolf, and beaver, have 
 long since been ^extirpated, and from these backwards still 
 to the seals, whales, and boreal shells that inhabited our 
 firths and estuaries in times immediately post-glacial. The 
 reader may readily trace this gradation in the estuarine 
 deposits of the Clyde, Forth, Tay, or any other of our 
 
 R 
 
258 EECENT FORMATIONS. 
 
 larger rivers. "We take, for example, Stratheden in Fife 
 (locally the " Howe " or hollow of Fife), and there, within 
 a distance of twenty miles, we have first the sand-banks 
 and sand-drift now in course of formation along the outer 
 estuary; a few miles inland a greyish " carse-clay," with 
 antlers of deer and bones of oxen, overlying a peaty layer 
 of forest-growth replete with the stumps and trunks of 
 the oak, pine, hazel, alder, birch, and willow, marking an 
 oscillation of the land;* and still further up the strath, 
 extensive deposits of sand and brick-clay, containing the 
 remains of whales, seals, northern sea-birds, arctic shells, 
 and star -fishes, usually regarded as immediately post- 
 glacial. 
 
 Of Eecent Formations, the next that fall to be con- 
 sidered are the Marine, or those accumulated in seas, and 
 whose imbedded remains are chiefly of oceanic growth and 
 habitat. Of course much of the sediment deposited in 
 the ocean is brought down by rivers from the surface of 
 the land, but we refer here to the areas in which it is col- 
 lected, and the manner in which it occurs. Marine silt 
 (mud, sand, and miscellaneous debris) is formed in every 
 sheltered bay and recess of the ocean, where, under the 
 influence of winds, waves, and tides, it gradually accumu- 
 lates till it banks out the water, and is converted into 
 tracts of low-lying alluvial land. The fens of Lincoln, 
 and the polders of Holland, are familiar examples in our 
 own seas ; and as these have been formed, so have similar 
 flats along every sea -shore favoured with the necessary 
 shelter and the necessary tidal sets. In many areas it will 
 
 * This submarine forest, which is well exposed at the railway bridge 
 across the affluent stream of the Motrie, is at the same level and of a 
 similar character with those occurring on the Tay, Forth, Humber, the 
 coast of Lincolnshire, Devonshire, Lancashire, and other localities. 
 
MARINE. 259 
 
 be difficult to distinguish between estuarine silts and silts 
 that are truly marine, but in all bays and recesses where 
 there is no great entering river, the formations may be 
 regarded as belonging exclusively to the sea. Besides 
 these Littoral or shore-formed silts, there are submarine 
 shoals and banks accumulating far from land, and sedi- 
 ments collecting in the stiller depths of the ocean. Every 
 chart bears witness to the numbers of these shoals and 
 banks, and in certain areas every throw of the sounding- 
 lead brings up evidence of the vastness of these Pelagic or 
 deep-sea deposits. On wave-washed shoals the accumula- 
 tions are usually sand and shingle ; but along the deeper 
 sea-bed they consist of slimy muds the " oaze " or " ooze " 
 of the navigator.* And were such pelagic deposits up- 
 raised into dry land, they would rival the older formations 
 alike in their geographical extent and in the diversity of 
 their mineral composition and organic remains. 
 
 Besides these truly marine sediments, there is another 
 set of accumulations of vast extent and peculiar interest, 
 which are partly marine and partly ^Eolian or wind-formed. 
 We allude to the sand-dunes, sand-drift, or links, which 
 border most of the bays in our own islands, and indeed the 
 bays and sea-shallows of every other country. Originally 
 formed in the sea, the sands dried during neap-tides are 
 
 * Speaking of this mud, Captain Dayman, in his ' Deep-Sea Sound- 
 ings/ says: "Between the 15th and 45th degree of west longitude lies 
 the deepest part of the ocean between Ireland and Newfoundland, vary- 
 ing from about 1500 to 2000 fathoms, the bottom of which is almost 
 wholly composed of the same kind of soft mealy substance, which, for 
 want of a better name, I have called oaze. This substance is remarkably 
 sticky, having been found to adhere to the sounding-rod and line through 
 its passage from the bottom to the surface, in some instances from a 
 depth of more than 2000 fathoms." On microscopic examination this 
 oaze was found to consist for the most part of foraminiferal organisms, 
 there being about 90 per cent of calcareous, and only 10 per cent of 
 siliceous matter ; the mass when dried greatly resembling chalk in colour 
 and consistency. 
 
260 RECENT FORMATIONS. 
 
 drifted inland, and piled up in fringes of dunes or hillocks 
 beyond the reach of the waves. By this process, continued 
 year after year, and century after century, the sea is gra- 
 dually banked back, and large sandy tracts created, terres- 
 trial and wind-blown above, but marine and water-drifted 
 below. We once watched the sinking of a well in the 
 sandy tract that stretches between St Andrews and the Tay 
 (Pilmoor and Tentsmoor Links) : the first fifteen or twenty 
 feet were through wind-blown sands and thin layers of 
 vegetable soil ; the remainder, to a great depth, was through 
 masses of sand, shells, gravel, and shingle, the drift of St 
 Andrews Bay when its waves rolled several miles farther 
 inland than they do now. As with this instance so with 
 others, whether along the shores of Holland, the Landes of 
 Biscay, or the Bights of Western Australia. These sand- 
 dunes, from narrow fringes of a few acres to rolling ex- 
 panses of many square miles in extent, may be witnessed 
 along the seaboard of every region, one of the most strik- 
 ing examples in Europe being the "Landes de Bour- 
 deaux " (stretching southward from the mouth of the 
 Garonne along the Bay of Biscay, and onwards towards 
 Bourdeaux), with their shifting sandhills along shore, their 
 dense forests of sea-pine farther inland, and beyond these 
 artificially planted shelters vast expanses of heathy undu- 
 lating sheep-runs. 
 
 In addition to these littoral silts and pelagic sediments, 
 there is another class of marine deposits which have of late 
 years much engaged the attention of geologists, partly from 
 their varying and vast antiquity, and partly from the evi- 
 dence they afford of repeated elevations of the land. We 
 refer to those " raised beaches " or " ancient sea-margins," 
 whose terrace-like flats are found fringing the seaboard of 
 almost every region. Were our own islands to be upraised 
 to the extent of twenty or thirty feet, the present shores 
 
CHEMICAL. 261 
 
 (unless where steep and rocky) would form a low fringing 
 terrace, here composed of gravel and shingle, there of sand 
 and shelly debris, and in another portion of silty sedi- 
 ments. So it is with these ancient beaches ; their compo- 
 sition is quite analogous, and their organic remains differ 
 with their relative antiquities, or, which is the same thing, 
 with their elevation above the existing sea-level. Such 
 aDcient sea-margins, at various heights (9, 25, 40, 63, and 
 120 feet), are very obvious along our own coasts, and, as 
 already adverted to under " Crust-Motions" (Sketch No. 3), 
 at still greater elevations (400 or 600 feet) along the shores 
 of Scandinavia, Spitzbergen, Siberia, Greenland, and arctic 
 North America. In South America also, both on the 
 Atlantic and Pacific sides, similar terraces are frequent and 
 boldly marked those in Peru and Chili containing the 
 " salinas," so valuable as the repositories of the salts of 
 soda, potash, and other kindred substances.* Wherever 
 they occur these ancient beaches notch the earth's surface 
 like a great scale of time descending from the glacial 
 epoch down to the present day ; all that is wanting being 
 the numerical expression of their successive stages in years 
 and centuries. 
 
 * The most important of these saline deposits (scientifically as well as 
 commercially speaking) are those of Iquique in Peru. From six to four- 
 teen leagues from the coast, and running parallel with it through the pro- 
 vince, at an elevation of 3000 feet or thereabouts, is the pampa of Tara- 
 mugal. This plain or pampa has evidently been a sea-lake, and in all 
 likelihood the result of elevation by volcanic agency. There are other 
 minor terraces or old sea-flats between the main pampa and the sea, but 
 that of Taramugal is the most important and productive. It consists in 
 some parts of many feet in thickness of sand indurated with salt, soft sand 
 with crystals of nitrate, and true caleches of concreted nitrate of soda 
 and stony debris. The other salts found in the deposit are chloride of 
 sodium (common salt), biborates of lime and soda, sulphates of lime and 
 soda, magnesian alum, &c. Iodine also exists with the nitrate, and 
 throughout the calacheros traces of boracic acid have been found in the 
 water the whole pointing unmistakably to the marine origin of the 
 deposits. 
 
262 RECENT FORMATIONS. 
 
 The next class of Recent Formations that falls to be 
 noticed, embraces all such as arise more immediately from 
 Chemical actions and reactions. It is true that chemical 
 changes are incessantly taking place in every formation, 
 whether of aqueous, of organic, or of igneous origin ; but 
 we allude in the present instance to those which, like tra- 
 vertine, sinter, bitumen, and the like, arise from deposition 
 and exudation by mineral springs and other causes chiefly 
 chemical. Every one must have observed how the " petri- 
 fying spring" of ordinary language incrusts the stems, 
 leaves, and stones that lie along its course, the limy incrus- 
 tation thickening with time, and varying in magnitude 
 according to the volume of the spring, and the amount of 
 lime held in solution in its waters. To this set of deposits 
 belong the travertines, cole-tuffs, and calc-sinters of the 
 mineralogist ; and the stalagmites and stalactites found in- 
 crusting the floors and depending from the roofs of caverns.* 
 These calcareous masses are found of all ages, from the 
 incrustations of the present century to the old cave-floors 
 imbedding the stone implements of primitive men and the 
 bones of extinct mammalia cave-lions, cave-bears, hyaenas, 
 mammoths, Irish elks, reindeer, and others, dating back 
 even to the tertiary epoch. As with calcareous depositions, 
 so also with those of a siliceous or flinty nature, which arise 
 generally from hot springs, such as those of Iceland, the 
 Azores, California, New Zealand, and other regions. These 
 siliceous tufas and sinters occur on a less extensive scale, 
 but they accumulate quite in the same manner, and imbed 
 
 * Travertines are light concretionary limestones deposited from waters 
 holding lime in solution, like those of the Arno and Tiber, hence Tibwtinus, 
 Travertinus ; Sinters (Ger. sintern, to drop) are compact calcareous and 
 siliceous incrustations ; tuffs or tufas, on the other hand, are light and 
 porous ; stalactites (Gr. slallaso, to drop) depend from the roofs of calcare- 
 ous caverns ; while stalagmites (Gr. stalagma, a drop) are the more massive 
 incrustations that accumulate on their floors. 
 
ORGANIC. 263 
 
 or silicify whatever organism comes in their way. To this 
 class of deposits "belong also all superficial accumulations of 
 saline substances (common salt, soda, nitrates of soda and 
 potash, borax, &c.), sublimations of sulphur, exudations of 
 bitumen and asphalt, and indeed all formations arising more 
 immediately from chemical action and reaction. Compared 
 with mechanical accumulations, they are usually of limited 
 dimensions, but they are often of curious interest, and their 
 study throws a flood of light on many of the older pheno- 
 mena of the rocky crust. 
 
 Among Recent Formations those of Organic origin that 
 is, arising from the growth and decay of plants and animals 
 are, perhaps, the most interesting and instructive. There 
 is no phenomenon more familiar to British readers than 
 the peat-mosses which occupy considerable tracts in every 
 part of the country, and which, before the extension of 
 modern agriculture, made their appearance over still wider 
 areas. These peat-mosses are entirely of vegetable growth 
 mosses, aquatic plants, heath, and fallen forests ; and 
 imbed isolated trunks of oak, pine, and birch, as well as the 
 remains of man, oxen, deer, and other animals that have 
 been swamped in their boggier portions. These accumula- 
 tions are of all ages, from the growth of the current year 
 back to the very close of the glacial epoch ; and their ex- 
 tent and thickness depend entirely upon the nature of the 
 area (its flatness, moisture, and shelter) in which they occur. 
 We have witnessed a depth of thirty feet reposing on blue 
 lake-silt which enclosed the remains of the extinct Irish 
 deer; while in another district similar silts have been found 
 beneath a peat-covering of less than a third of that thickness. 
 We have seen Eoman remains of the time of Agricola found 
 at a depth of twelve feet ; while in other tracts we have ex- 
 amined the hewn stumps of trees, the plank-roads, the lost 
 
264 RECENT FORMATIONS. 
 
 armour and coins of the same invaders, at a depth of not 
 more than five feet, and this all that had accumulated since 
 the time they marched their legions across the Lowlands of 
 Scotland. As with the peat-mosses of Britain, so with 
 those of Holland and the north of Europe generally, those 
 of Canada, and North America, and indeed of all tem- 
 perate and coldly-temperate latitudes. They are of all ages, 
 of varying dimensions and thickness, and of all degrees of 
 purity, from masses wholly and exclusively vegetable, to 
 others more or less intermingled with earthy debris, or 
 with the siliceous and ferruginous accumulations of micro- 
 scopic plant-growths and animalcules. In warmer latitudes, 
 swamp-growths, jungle-growths, and other kindred vege- 
 table accumulations make their appearance, the vegetable 
 mass in these cases being more macerated and decayed than 
 in the true peat-moss, but still wholly or almost wholly of 
 organic origin. These peats and swamp-growths are in 
 reality the coal-formers of the present day (see Sketch No. 
 9); nor let it be thought that in the aggregate they are 
 either of inconsiderable thickness or of limited surface. 
 In the peat-bogs of Europe, 20, 30, and 40 feet are no un- 
 common depths ; the tundras of Northern Asia, though 
 less pure in composition, are of much greater extent and 
 thickness; the " Dismal Swamp" of the Southern States 
 of America is 40 miles long by 25 miles broad ; the peat- 
 moss of Anticosti is stated by Sir William Logan to be 80 
 miles long, with an average width of two miles; and those 
 in the lake regions of sub-arctic America are of still more 
 extensive dimensions. 
 
 As with vegetable accumulations, so with those of animal 
 origin the coral-reefs, shell-beds, foraminiferal deposits, 
 bone-shoals, and guano islands of the current epoch. The 
 most obvious of these are perhaps the coral-reefs the slow 
 but incessant secretions of myriad polypes within all the 
 
ORGANIC. 265 
 
 warmer latitudes and shallower depths of the ocean. 
 "Within thirty degrees on either side of the equator, and at 
 depths within twenty fathoms, these polypes in numerous 
 genera are perpetually piling up their beautiful calcareous 
 structures ; here encircling lagoons, there fringing islands, 
 and in another area extending in long ridge-like barriers. 
 Many of these coral-reefs are of vast extent the great 
 " Barrier" of ]N"ew Holland being upwards of 1000 miles 
 in length, and from 20 to more than 100 feet in thickness; 
 and in all, the mass is essentially composed of coral 
 structure, but intermingled more or less with shells, crusts, 
 coral-debris, and other extraneous substances. There is 
 nothing more marvellous than this enormous secretion' of 
 rock-matter by the tiniest of agencies ; nothing more over- 
 whelming to the conception than the number of individual 
 organisms concerned in the work ! And yet as it is now, 
 so it has been in all time past ; the same agencies have ever 
 secreted the surplus lime from the ocean-waters, and built 
 their reefs much in the same dimensions and much after the 
 same style of construction. As with coral-reefs, so with 
 serpula-reefs (annelids that secrete calcareous cases); shell- 
 beds^ whether drifted or buried in situ ; bone-shoals drifted 
 by currents, or frequented by fishes, seals, and other creatures 
 that die and accumulate in myriads; and with guano-deposits ', 
 the droppings of sea-fowls that have accumulated under a 
 rainless sky for ages. All are alike of animal origin, and 
 all are alike returning to the sblid crust that which other 
 agencies had dissipated and dissolved. The importance of 
 these organic deposits serpula-reefs 12 or 15 feet thick, 
 like those of Bermuda ; shell-beds many leagues in extent, 
 like those of the Indian Ocean ; bone-shoals like that lying 
 in the North Sea between the Faroe Islands and Iceland ; 
 and guano-deposits 40, 60, or 80 feet thick, like those off 
 the coast of Peru are not sufficiently recognised by geolo- 
 
266 RECENT FORMATIONS. 
 
 gists. As a curious illustration, we may notice the island 
 of Sombrero, one of the West India group, which is almost 
 entirely of organic origin. This islet, so called from its re- 
 semblance to a " sombrero," or low-crowned Spanish hat, 
 and situated about 130 miles east of Porto Rico, is about 
 two and a half miles long, one-half to three-fourths of a 
 mile wide, and rises from 20 to 30 feet above the level of 
 the ocean. It is a barren rock, and appears to be entirely 
 composed of the rich phosphatic mineral known in com- 
 merce as Sombrero guano. This substance imbeds numer- 
 ous bones of turtles and other marine animals ; and from 
 its composition, which resembles bones deprived of their 
 cartilage, it has been supposed (with every degree of proba- 
 bility) that the island was once a shoal swarming with 
 turtles and other vertebrate animals, whose accumulated 
 remains of ages have been cemented together, and gradually 
 elevated above the ocean-level to the present position of the 
 island. The history of such an accumulation is interesting 
 not only on its own account as a Recent Formation, but 
 from the light which it throws on the origin of osseous 
 breccias belonging to earlier epochs. 
 
 Besides these more obvious operations of plants and 
 animals, there are others equally extensive though less 
 apparent. The very lowest forms of life organisms that 
 stand, as it were, between the confines of the vegetable and 
 animal kingdoms, and which require the aid of the micro- 
 scope to reveal their forms are equally busy, in equally 
 inconceivable numbers, in accumulating their calcareous 
 and siliceous remains. The calcareous oaze or mud of the 
 deep seas, extending for thousands of miles, and of unknown 
 thickness, is, as we have seen under the head of Marine 
 formations, chiefly composed of the minute shells of fora- 
 minifera ; and many siliceous muds in lakes, estuaries, and 
 even in the deeper waters, are composed in like manner 
 
THEIR CHRONOLOGICAL STAGES. 267 
 
 of the flinty shields of polycistinae and diatomacese. The 
 foraminifers and polycistines belong to the animal kingdom, 
 the diatoms to the vegetable ; but all require the higher 
 powers of the microscope for their study, and when ob- 
 servers speak of miles of diatomaceous earths, and thou- 
 sands of miles of foraminiferal muds, the mind is utterly 
 impotent to grapple with the conception of the numbers 
 of individual organisms that must have contributed their 
 quota to the aggregate amount. But so it often happens 
 in nature, that the most gigantic results are brought about 
 by the minutest agents, and by the most imperceptible 
 stages the main conditions being incessant activity and 
 unlimited duration. 
 
 The last of the Eecent Formations that fall within the 
 scope of our Sketch are the Volcanic, or those that have 
 arisen from the substances discharged by modern volcanoes. 
 These formations will consist mainly of lava in its different 
 varieties, of tufa or compacted dust and ashes, of sconce 
 or cindery and slaggy matter, of pumice, obsidian, lapilli, 
 and agglomerates that have accumulated by the washing 
 together of heterogeneous volcanic products. The pro- 
 ducts of every active volcano are more or less an epi- 
 tome of those of all the rest ; for though some, like those 
 of the Andean cones, consist mainly of light cindery dis- 
 charges, the great majority are admixtures, in varying 
 sheets and masses, of all the substances above enume- 
 rated. Kow a shower of dust and ashes blown aloft and 
 scattered over one or other side of the mountain ; now an 
 overflow of lava slowly wending its way for miles down 
 the rugged slopes; now explosive discharges of slag and 
 cinders ; and anon some gigantic lava-stream enveloping 
 the whole in its rocky mass again to be overlaid by re- 
 peated successions of similar materials. Etna, Vesuvius, 
 
268 RECENT FORMATIONS. 
 
 and Hecla may be taken as familiar instances of volcanic 
 accumulations, and as these have added hundreds of feet to 
 their height, and cast their discharges for miles around dur- 
 ing the current epoch, so have all other active volcanoes 
 "been similarly adding to their altitudes and lateral dimen- 
 sions. One has only to cast his eye over a map of Volcanic 
 Lines and Centres to see what a large area of the globe 
 must have received accumulations of this kind within modern 
 times partly as mountain masses piled up on land, partly 
 as islands upheaved from the sea, and partly as submarine 
 sheets that have flowed as lava, or been cast abroad in 
 showers of dust and ashes. All along the Andes, Central 
 America, Mexico, the West Indies, and the north-western 
 shores of the New World, volcanic accumulations have 
 taken place, and are still taking place, on a grand scale. 
 The same may be said of the Aleutian Islands, Kamtchatka, 
 Japan, the Philippines, and the East Indian Archipelago ; 
 while over the bosom of the Pacific, along the Atlantic 
 islands of Africa, in the Indian Ocean, in the Southern 
 Ocean (as New Zealand), and in the Northern (as Iceland), 
 similar phenomena have marked the course of the Tertiary- 
 period, and must, if we can judge from their present dis- 
 plays, have materially contributed to the exterior crust of 
 our planet. Indeed, as there is no other Recent formation 
 more obvious in its character and mode of accumulation, 
 so there is none more rapid and gigantic in its results 
 a few months being often sufficient to pile up hills of slag 
 and scoriae, or spread abroad sheets of lava hundreds of feet 
 in thickness, and many square miles in extent.* But it is 
 
 * Sir W. Hamilton reckoned the current which reached Catania in 
 1669 to be 14 miles long, and in some parts 6 wide ; Recupero measured 
 the length of another, upon the northern side of Etna, and found it 40 
 miles ; Spallanzani mentions currents 15, 20, and 30 miles ; the stream 
 that flowed from the Skaptar Jokul in Iceland in 1783 was about 50 miles 
 
THEIR CHRONOLOGICAL ST 
 
 not to the mere volcano alone that we mi 
 full effects of vulcanic energy. The earthquake 
 motions alluded to in a former Sketch (No. 3) are in like 
 manner ever busy in moulding and modifying the earth's 
 exterior the former fracturing and fissuring the rocky 
 crust, and giving tenfold significance to the discharges of 
 the volcano, the latter silently elevating the sea-hed into 
 dry land, or submerging the dry land beneath the waters. 
 
 Such is a rapid sketch of the Post-Tertiary or Quaternary 
 formations, which, though recent and superficial to us, will 
 become old and deep-seated to the observers of future ages. 
 Scattered over the land, and spread out under the waters, 
 they are not only everywhere present, but of all dates, 
 from the accumulations of the current century back to those 
 that mark the close of the glacial epoch. Indeed, the main 
 difficulty connected with them is to assign their respective 
 dates, and fix a scale of chronology that will be at all gene- 
 rally applicable. Superposition can only be applied in very 
 limited cases; and mineral composition is of little avail, 
 as the older are often as loose and unconsolidated as the 
 younger. The only satisfactory test is fossils, striking back 
 from the existing flora and fauna of any locality to those 
 that have been removed from that locality, and from these 
 back to such as have become totally extinct. In this way 
 we may speak of Upper, or those containing existing plants 
 and animals ; of Middle, or those characterised by plants 
 and animals locally extirpated j and Loicer, or those marked 
 by organisms now wholly extinct. As regards Man, they 
 
 long, by 12 or 15 in its greatest breadth, and from 20 to 600 feet in 
 thickness, according to the nature of the ground ; while Dr Coan esti- 
 mates the discharge of Mauna Loa (one of the Sandwich Island volcanoes) 
 in August 1855, at 70 miles long, with a varying width from 1 to 5 miles, 
 and from ten to several hundred feet in thickness. 
 
270 RECENT FORMATIONS. 
 
 may "be arranged into Pre-human and Human the former 
 containing no traces of man or of his works, the latter being 
 here and there characterised by such remains. And even this 
 Human period may be conveniently subdivided into Pre- 
 historic and Historic the former, like the flint implements, 
 shell-mounds, and cave-dwellings, dating back far beyond 
 the reach of history, the latter coming within periods to 
 which we can assign something like a date in years and 
 centuries. But whatever the arrangement, we clearly per- 
 ceive that some are very ancient so ancient as to merge 
 into the close of the glacial period, and others very recent 
 so recent as to be still in progress of formation. Nor let it 
 be imagined that, because recent, these accumulations are 
 limited and insignificant. All that is necessary to make 
 them rival the older formations in extent and thickness is 
 time, and this is an element as unlimited in the future as 
 it has been prodigal in the past. 
 
 During the deposition of the more ancient, the mam- 
 moth, woolly-haired rhinoceros, hippopotamus, cave-lion, 
 cave-bear, hyaena, and great Irish deer, were inhabitants of 
 Western Europe ; herds of mastodon roamed over the river 
 and lake flats of North America; the plains of South 
 America were densely peopled by the megatherium, megal- 
 onyx, glyptodon, mylodon, and macrauchene ; and Austra- 
 lia, with more gigantic forms of kangaroo and other marsu- 
 pials. At this period we have no traces of man save in 
 Southern and Western Europe * (the only tracts yet suffi- 
 ciently examined) ; and there savage races seem to have lived 
 in caves and wigwams, fashioned stone and flint implements, 
 
 * "We do not lose sight of the fact, that implements fashioned out of the 
 native quartzite of India have been found in the alluvial laterite of Madras 
 and North Arcot, but merely hold it subordinate till the discovery of as- 
 sociated organisms enable geologists to form a more definite idea of the 
 relative antiquity of these lateritic deposits. 
 
THEIR CHRONOLOGICAL STAGES. 271 
 
 and subsisted chiefly by hunting and fishing. During the 
 deposition of the less ancient or middle formations the 
 earlier fauna had in a great measure disappeared, and species 
 of ox, deer, horse, wild-hog, wolf, bear, and other existing 
 genera had taken their places. To this period belong the 
 extinct species of ox, horse, and deer, which have been found 
 alike in Europe and America ; and perhaps also the gigantic 
 ostrich-like birds of Madagascar and New Zealand the 
 aepiornis, dinornis, palapteryx, and their congeners. The 
 men of Western Europe still fashion their stone and bone 
 tools and tree-canoes; but traces of underground stone- 
 dwellings, and pile-dwellings in lakes, with doubtful indica- 
 tions of metal implements, bespeak an advance and mark 
 the first stages from savagery to civilisation. During the 
 deposition of the more recent, the flora and fauna of every 
 region have remained much as we now behold them.* A few 
 general extinctions, like the dodo, solitaire, great auk, and 
 rhytina,t have been recorded ; hundreds of local extirpa- 
 tions and removals (like the original flora and fauna of our 
 
 * According to Professor Heer, the native flora and fauna of Switzerland 
 have remained much the same since the time of the earliest lake-dwell- 
 ings, while the cultivated plants and domesticated animals have passed 
 into totally different varieties. If this observation be correct, it tends to 
 show that organic changes are slow or rapid in proportion to the physical 
 changes to which life is subjected, and that where the physical surround- 
 ings undergo slow and gradual mutations (which is the common course of 
 nature) plants and animals may exhibit little variation for ages. It is 
 thus that the specific changes recorded by Palaentology afford the strongest 
 evidence of the incalculable lapse and length of geological time. 
 
 f The circumstances connected^with the extinction of the dodo, soli- 
 taire, and great auk, are well known. The rhytina, a phytophagous 
 Sireiiian, discovered by Steller on Behring Island in 1741, is also consid- 
 ered as completely extirpated the last individual having been killed in 
 1768. Unlike the manatees or sea-cows, the rhytina was edentate, having 
 special bony palatal apparatus for the crushing of its food. Its sub-fossil 
 remains (from 8 to 24 feet in length) are now eagerly sought after for our 
 public museums, and one or two specimens, we believe, were exhumed in 
 1864. 
 
272 RECENT FORMATIONS. 
 
 own islands) have taken place under the aggressions of 
 man; and man himself has risen through the successive 
 stages of stone, bronze, and iron, to what we now behold 
 him. We pass from pre-historic to historic times, but still 
 there is no cessation. The agencies of nature are as busy 
 now in moulding and remodelling the rocky crust as ever 
 they were. From their slow and gradual operation we may 
 fail to appreciate the results ; to the future, however, they 
 will appear in all their vastness and universality. 
 
MAX'S PLACE IX THE GEOLOGICAL KECOKD. 
 
 THE GEOLOGICAL RECORD NATURE OF ITS CHRONOLOGICAL STAGES- 
 DIFFICULTIES AND IMPERFECTIONS COMPARATIVE RECENTNESS OF 
 MAN'S PLACE NATURE OF THE EVIDENCE PREJUDICES TO BE 
 COMBATED MAN*S EARLIER LIFE - COMPANIONS IN SOUTHERN 
 AND WESTERN EUROPE THEIR REMOVALS AND EXTINCTIONS 
 TRACES OF HIS OWN RACE PRE-HISTORIC AND HISTORIC AGES 
 OF STONE, BRONZE, AND IRON SHELL-MOUNDS, CAVE-DWELLINGS, 
 LAKE-DWELLINGS, ETC. MAN IN OTHER REGIONS GENERAL 
 QUESTION OF MAN'S ANTIQUITY HOW TO BE SOLVED. 
 
 UNLIKE the periods of human history, those of Geology 
 have no definite expression in years and centuries. We 
 speak of eras and epochs, of cycles and systems, but these 
 are merely relative terms. They have no definite duration ; 
 the one merely precedes the other, and the larger may in- 
 clude many recurrences of the lesser within its limits. In 
 speaking of geological time this is all that is signified ; in 
 fixing the dates of geological events this is all that can be 
 fairly asserted. The Primary merely precedes the Secondary, 
 the Secondary the Tertiary, and the Tertiary the events of 
 the Current epoch. "We may subdivide these greater stages 
 into narrower limits, and talk of Laurentian, Cambrian, 
 Silurian, Devonian, Carboniferous, Permian, Triassic, Ooli- 
 tic, Cretaceous, Tertiary, and Eecent rock-systems, and this 
 is no doubt restricting events to more precise bounds, but 
 it gives no definite idea of duration, nor tells us how long 
 the Chalk preceded the Tertiary, or the Tertiary the occur- 
 
 s 
 
274 MAN'S PLACE IN THE GEOLOGICAL EECORD. 
 
 rences of the existing epoch. We can judge from its thick- 
 ness, and the nature of its rocks and fossils, that one sys- 
 tem took much longer time to accumulate than another, 
 "but we cannot venture, by any known method of compu- 
 tation, to say how long in years. All that we have to do 
 with is relative time ; and even in dealing with the current 
 epoch, should we assert that certain events took place more 
 than six thousand or eight thousand years ago, we are 
 simply asserting a provisional opinion, and not maintain- 
 ing a belief like that founded upon the written record of 
 human history. 
 
 The geological record is thus relative and not absolute ; 
 and when we arrange it, as in the subjoined tabulation, 
 into Primary, Secondary, Tertiary, and Quaternary, we are 
 merely asserting a certain order of succession, and this suc- 
 cession not always clearly defined over certain areas. In- 
 deed, it is often impossible to define the boundaries of the 
 minor stages, portions having been removed by denudation, 
 others overlaid by more recent deposits, and some being 
 partially submerged beneath the waters of the ocean. Again, 
 though the thickness of one formation may seem to have 
 required a longer time for its accumulation than another of 
 smaller dimensions, yet in the one case the rate of deposi- 
 tion may have been much more rapid than in the other, 
 and the thinner may, after all, have required the longer 
 period. Still further, though organic remains are most im- 
 portant aids, yet they are often absent from certain beds, or 
 if there, these beds are not sufficiently exposed to investi- 
 gation, and our information becomes in this way fragmen- 
 tary and defective. Neither in sequence of events, nor in 
 expression of time, does Geology lay claim to exactitude. 
 Its cultivators are successfully labouring to complete the 
 one, and they are hopeful of arriving at more definite terms 
 in the other ; but this is all in the mean time, and the fol- 
 
STAGES OF THIS RECORD. 275 
 
 lowing arrangement expresses the amount of their infor- 
 mation : 
 
 CAIXOZOIC f Quaternary or Kecent formations. 
 
 (Recent Life.) \ Tertiary. 
 
 MESOZOIO ( Cretaceous or Chalk. 
 
 (Middle Life) 1 Oolitic or Jurassic. 
 
 t Triassic or Upper New Bed Sandstone. 
 
 {Permian or Lower New Red Sandstone. 
 Carboniferous or Coal System. 
 Old Red Sandstone and Devonian. 
 Silurian. 
 
 Eozoic ( Cambrian. 
 
 (Dawn Life.) \ Laurentian. 
 
 In this arrangement the terms Eozoic, Palaeozoic, Mesozoic, 
 and Cainozoic, indicate the chronological stages having re- 
 ference to the ascent of life ; and Laurentian, Cambrian, 
 Silurian, &c., those having reference to the different for- 
 mations whose depositions mark the successive physical 
 operations of nature. By this arrangement the geologist 
 simply asserts that the Laurentian preceded the Cambrian, 
 and the Cambrian the Silurian, but no opinion is expressed 
 as to the amount of time required for the deposition of the 
 Laurentian, or whether the Cambrian occupied a longer 
 time in formation than the overlying Silurian. We may 
 feel convinced, from the total thickness of a system, the 
 alternations of its strata, and the succession of its fossils, 
 that it occupied a much longer time in formation than 
 another system ; but this is not expressed in the above 
 arrangement, which merely affirms a sequence from older 
 to younger, and from the earliest ascertainable operations 
 to those still taking place around us. 
 
 Such is the chronology of Geology a chronology to which 
 investigators endeavour to conform the rock-formations of 
 the globe j and although the Chalk of one country, for ex- 
 ample, may not have been exactly contemporaneous with 
 
276 MAN'S PLACE IN THE GEOLOGICAL RECORD. 
 
 the Chalk formation of another region, still we know that 
 it stands intermediate between the Oolite and Tertiary, and 
 can therefore assign to it a place relatively to these forma- 
 tions. In some region yet unexplored a whole suite of 
 strata may be discovered older than our Carboniferous, and 
 yet younger than our Old Red, and in such a case geolo- 
 gists would give the new formation a name, and place it as 
 intermediate between these two systems. It would disturb 
 no established order, but merely render more complete the 
 sequence, like the interpolation of a hitherto unknown reign 
 in the dynasties of human history. The geological record 
 is thus a thing of mere sequence an inconceivable amount 
 of unexpressed time, during which certain events follow each 
 other in definite order. How many ages have elapsed since 
 the first deposition of the Laurentian strata we cannot tell ; 
 how many centuries were spent in the formation of the 
 Coal-measures of any locality, we can only, estimating from 
 existing operations, offer the widest conjecture. But we 
 can affirm with certainty, and this is a great point gained, 
 that one rock-system is younger than another ; that these 
 rock-systems follow in the order above given ; that accord- 
 ing to our present knowledge invertebrate life preceded the 
 vertebrate ; that fishes preceded reptiles, reptiles birds, and 
 birds mammalia.* We can also affirm, what it is the ob- 
 ject of the present Sketch to prove, that as there has been 
 an ascent in time from lower to higher forms of life, so 
 Man, being the highest known creature, comes latest on the 
 geological stage, and that evidences of his existence are to be 
 found only in the most recent and superficial formations. 
 
 It will be seen from the preceding statements that the 
 geological record is avowedly indefinite and defective in- 
 definite, as it deals only with relative time ; and defective, 
 as many strata cannot be assigned to their proper positions, 
 * See tabulation of ascending orders, p. 29. 
 
THE READING OP THIS RECORD. 277 
 
 partly from the obscurities of superposition, and partly from 
 the absence of typical fossils to connect them. But, while 
 admitting this defect in details, it must not be imagined 
 there is any uncertainty as to the broader features of the re- 
 cord, or that any new discoveries have ever been at variance 
 with the great order of sequence which modern geology has 
 established. Man, so far as every known fact tends to 
 indicate, belongs exclusively to the Eecent or Post-tertiary 
 period. No remains of his kind, no fragment of his works, 
 no traces of his presence, have ever been detected in earlier 
 formations. But though this is admitted on all hands, the 
 question still remains, at what stage of the Post-tertiary 
 are traces of his existence first detected ? Till recently the 
 general belief has been that man's first appearance on the 
 globe dates back, at the very most, to little more than six or 
 seven thousand years ; and so incorporated had this belief 
 become with others of a more sacred character, that few, 
 even though doubting, had the boldness to express a con- 
 trary conviction. Like the age of our planet, which was 
 also at one time restricted to a few thousand years, the 
 antiquity of man has become a question of science and 
 reason ; . and well-informed minds are now prepared to admit 
 that as the earth has existed for untold ages, so man, its 
 latest creation, may have inhabited its surface for hundreds 
 of centuries. The evidence is purely geological, and as 
 such ought to be treated like any other problem in science, 
 without bar or hindrance from preconceived opinion ; or, as 
 it has been well said by Bishop Tait, in his address to the 
 Philosophical Institution of Edinburgh, " The man of 
 science ought to go on honestly, patiently, diffidently, 
 observing and storing up his observations, and carrying his 
 reasonings unflinchingly to their legitimate conclusions, 
 convinced that it would be treason at once to the dignity 
 of science and of religion, if he sought to help either by 
 
278 MAN'S PLACE IN THE GEOLOGICAL BECOED. 
 
 swerving ever so little from the straight rule of truth." In 
 investigating the antiquity of man we are dealing with a 
 question of natural history, and are "bound "by the same 
 methods of research as if we were treating of the history 
 of the mammoth or mastodon. Our business as geologists 
 is to examine the rock-formations composing the earth's 
 crust, to note their imbedded organisms, and to fix their 
 relative antiquities. Wherever the remains of man or of 
 his works occur, there, we presume, has been his presence ; 
 and though we cannot assign any definite date to the time 
 of such occurrence, we are at all events entitled, judging 
 from all the correlative circumstances, to say that it took 
 place more than six thousand, ten thousand, or twenty 
 thousand years ago. In other words, we are bound to deal 
 with Man's antiquity as with any other question in geo- 
 logy ; and though our dates be merely relative, we can 
 affirm the order of sequence, and arrive at some notion 
 of duration from the rate of existing operations. 
 
 Abiding by these methods, we find the remains of man 
 and of his works gradually receding from the historical into 
 the pre-historic ages. In Southern and Western Europe 
 the only regions that have been examined with anything 
 like geological accuracy these remains occur in peat-mosses, 
 in lake-silts, river-drifts, and cave-earths, and from their 
 associated organisms we judge of their relative antiquities. 
 If they occur along with the remains of the existing horse, 
 ox, sheep, pig, and the like, we know that they are compa- 
 ratively recent, and in all probability belong to the historic 
 era. If, on the other hand, they are found accompanied by 
 remains of extinct species of horses and oxen, we know 
 they are of greater antiquity ; and if such horses and oxen 
 are not spoken of in history, or represented in human monu- 
 ments, then we are entitled to regard them as pre-historic. 
 Or again, if they are associated with remains of the great 
 
THE READING OF THIS RECORD. 279 
 
 Irish deer, the mammoth, mastodon, woolly-haired rhino- 
 ceros, and other animals long since extinct, we feel assured 
 that vast changes in physical geography have taken place 
 since their entombment, and are entitled to assign to them 
 a still higher antiquity. In fact we know that all changes 
 in physical conditions, and all removals and extinctions 
 of life, take place by slow and silent stages, and that the 
 greater the diiference between the existing and the extinct, 
 the longer must be the time that has elapsed since their 
 extinction. By methods such as these we can establish a 
 scale of old, older, oldest ; and there need be no more un- 
 certainty about the results obtained by such methods than 
 there is about the results obtained by the historian in 
 modern, medieval, and ancient history. 
 
 Another method by which we arrive at notions of relative 
 antiquity is by the implements and works of art that occur 
 in recent formations, or accompany the remains of man. 
 "We know the phases of modern, medieval, Eoman, Greek, 
 Egyptian, and Babylonian art, and can assign something 
 like a historical date to such objects and the accumulations 
 in which they occur. We know, too, that man employs tools 
 of wood and stone long before he learns the uses of the 
 metals; and that he reduces the softer metals, and works in 
 copper and bronze, long before he has acquired the mastery 
 over iron and steeL In this way we speak of the ages of 
 stone, bronze, and iron, the one preceding the other, and 
 forming, as it were, a rude scale of time for the antiquarian 
 and geologist But while one nation may be working in 
 iron, another more belated may be working in bronze, and 
 a third, still more remote and savage, may be adhering to 
 implements of wood and stone. To be of any use, this 
 scale of stone, bronze, and iron, must be applied to the same 
 district; and when so applied, archaeologists are now pretty 
 well agreed that it marks with considerable certainty the 
 
280 MAN'S PLACE IN THE GEOLOGICAL EECOED. 
 
 various stages of relative antiquity. Of course, were im- 
 plements of iron ever found along with remains of mam- 
 moth and mastodon, the scale would "be utterly worthless ; 
 hut when stone tools invariahly accompany the older re- 
 mains, and those of bronze and iron those of younger and 
 younger date, then we feel assured from this concordance of 
 the implement scale with that of the animal that we have 
 hit upon a pretty exact method, so far as Europe at least 
 is concerned;* and it is by both of those modes that man's 
 place in the geological record has been mainly determined. 
 It will be seen that in speaking of implements of stone, 
 bronze, and iron, the geologist is trenching on the field of 
 archaeology, and the archaeologist on that of geology. Both 
 must, in fact, lend their aid in solving the question of 
 man's antiquity ; and whether it be by sepulchral barrows, 
 by shell-mounds the old feasting-stations of our northern 
 ancestors by pile-dwellings in lakes, or by flint implements 
 in river-drifts, much the same kind of reasoning must be 
 employed by both. A lake-dwelling, with implements of 
 stone and bronze, may carry us no further back than the 
 time of the Romans ; while a tree-canoe, hollowed out by 
 fire, and found under twelve or fourteen feet of river-silt, 
 may take us thousands of years before Eome had a founda- 
 tion. The inhabitants of Northern Europe may have lived 
 on shell-fish and been wrapt in skins when the Pharaohs 
 were clothed in fine linen and purple j but when we find 
 
 * Some archaeologists divide the Stone Period into the paleolithic and 
 neolithic stages the former the age of rude stone implements, and when 
 man shared the possession of Europe with the mammoth, the cave-bear, 
 the woolly-haired rhinoceros, and other extinct animals ; and the latter 
 the age of polished stone implements, and when man began to domesti- 
 cate the dog, ox, horse, and other existing mammalia. In this way we 
 have four stages of pre-historic time : 1, the Ancient Stone age ; 2, the 
 Newer Stone age ; 3, the Bronze age ; and, 4, the Iron age. For much 
 interesting and well-condensed information on this topic, see Lubbock's 
 1 Pre-historic Times/ 1865. 
 
THE READING OF THIS RECORD. 281 
 
 stone implements associated with worked horns of the 
 great Irish elk and reindeer, and with bones of the musk- 
 ox, mammoth, and woolly-haired rhinoceros, and these in 
 silts and drifts that indicate great physical changes in the 
 geography of Europe, then we may rest assured that these 
 monuments are pre-historic and of unknown antiquity. We 
 have no indication in history that the mammoth, rhinoceros, 
 or Irish deer were inhabitants of Southern and Western 
 Europe ; nothing either in history or tradition that points 
 to the time when the reindeer and musk-ox roamed in the 
 latitudes of France and England. It is true that natural 
 events are rarely noticed in ancient history, and especially 
 those of slow and gradual occurrence like the facts of geo- 
 logy; still it maybe safely asserted that during the historic 
 period none of the animals above referred to were inhabi- 
 tants of the southern and western portions of our continent. 
 Whatever the date of these stone implements, and their 
 associated mammoth and rhinoceros remains, they clearly 
 belong to pre-historic times; and the question is thus 
 narrowed to the relative antiquities of certain events which 
 occurred far beyond the reach of the oldest history and 
 the remotest traditions. 
 
 In dealing with pre-historic monuments, we may adopt 
 either the methods of the archaeologist, who founds chiefly 
 on the comparative rudeness and simplicity of the relics, or 
 those of the geologist, who looks mainly to the superposi- 
 tion of the beds in which the relics occur, or those of the 
 palaeontologist, who argues from the specific differences of 
 the flora and fauna ; or we may adopt a mixed method, and 
 reason from all that archeology, geology, and palaeontology 
 supply. Adopting this latter plan, we reason from the 
 lake-silts, peat-mosses, and deltic deposits containing stone 
 implements and tree-canoes, associated with the bones of 
 extinct varieties of the horse and ox, back to similar depo- 
 
282 MAN'S PLACE IN THE GEOLOGICAL RECORD. 
 
 sits and cave-earths imbedding ruder implements and re- 
 mains of the Irish deer, reindeer, and musk-ox, and from 
 these again to deeper river-gravels and brick-earths con- 
 taining implements still simpler in fashion, and associated 
 with the relics of mammoth and rhinoceros. Considerable 
 changes in the physical geography of Europe must have 
 taken place (as these silts and peat-growths imply) since 
 the time of the primitive horse and long-fronted ox ; still 
 greater must have taken place since the reindeer and musk- 
 ox found a suitable climate in the latitude of France and 
 England j and greater still since the mammoth roamed in 
 the pine forests and over the plains of the same regions. 
 Admitting the changes, the question remains, How shall 
 we estimate the lapse of time required for their fulfilment ? 
 If they are changes of a physical kind, we estimate accord- 
 ing to the rate at which similar changes are taking place 
 at the present day ; if of a vital kind, by the rate at which 
 extinctions and creations seem to have been effected in 
 former epochs ; and if of a kind involving the progress of 
 our own race, we know that civilisation in the long-run is 
 only arrived at, even under the most favourable circum- 
 stances, by slow and gradual stages. 
 
 Guided by these methods, the pile-dwellings in lakes (the 
 pfahlbauten of Switzerland and the crannoges of Ireland 
 and Scotland*) carry us back to the earlier Celtic times, 
 and may range from two to four thousand years, but clearly 
 they are not of the vast antiquity some archaeologists have 
 imagined, and though pre-historic in Europe, may have been 
 contemporary with historical events in Egypt and Western 
 Asia. Estimated by the implement-scale, they belong alike 
 to the ages of iron, bronze, and stone, and mark the long 
 occupancy of South-western Europe by the same partially 
 civilised but gradually improving race. As regards the 
 * For an account of these Lake-dwellings, see note, p. 254. 
 
PRE-CELTIC PERIODS. 283 
 
 shell -mounds (the Kjokken-modding* of Denmark) and 
 cave-dwellings of Belgium and France, they seem to indi- 
 cate the presence of a pre-Celtic people, simpler in their 
 mode of life, less civilised, and only acquainted with the 
 use of implements in stone, wood, and "bone. Smaller in 
 stature than the Celt, round-headed, hunters and fishers, 
 these pre-Celtic races never seem to have cultivated the soil, 
 or to have settled down in fixed situations. "Western 
 Europe appears to have "been their home before the Celts 
 left the mountains of the East ; and five or six thousand 
 years ago may mark the date of their occupancy of the 
 regions where now are found their shell -mounds, cave- 
 dwellings, and kindred reliquiae. Still earlier than these 
 pre-Celts, Southern Europe to the shores of the Mediter- 
 ranean, and Western Europe to the limits of the British* 
 Islands, seem to have been occupied by a ruder but perhaps 
 kindred race the fashioners of flint implements, and the 
 contemporaries of the reindeer, the mammoth, and woolly 
 rhinoceros. Reindeer, hairy elephants, and woolly-haired 
 rhinoceroses, in the latitudes of France and England, bespeak 
 a severer climate than at present prevails, and under this 
 boreal climate these rude races seem to have earned a scanty 
 subsistence, by hunting and fishing along shore, by lake, 
 
 * Literally " kitchen-middens ; " the name given by the Danes to cer- 
 tain mounds which occur along their sea-coasts, and which consist 
 chiefly of the castaway shells of the oyster, cockle, periwinkle, and other 
 edible kinds of shell-fish. These mounds, which have also been found 
 on the shores of Moray and the north of Scotland, are from 3 to 10 feet 
 high, and from 100 to 1000 feet in their longest diameter. They greatly 
 resemble heaps of shells formed by the Red Indians along the eastern 
 shores of the United States, before these tribes were extirpated. The 
 " kitchen-middens " of Europe are ascribed by archseologists to an early 
 people unacquainted with the use of metal, as all the implements found 
 in them are of stone, horn, bone, or wood, with fragments of rude pot- 
 tery and traces of wood-fires. All the bones yet found are those of wild 
 animals, with the exception perhaps of the dog, which seems to have 
 been domesticated. 
 
284 MAN'S PLACE IN THE GEOLOGICAL KECORD. 
 
 and by river-side. And it is generally in such situations 
 that their flint implements are found associated with the 
 bones and tusks and horns of these extinct mammalia. 
 But these implements (like those of Abbeville, &c.) are 
 often found at great depths, and at "altittdes above the 
 levels of existing rivers, that prove the occurrence of great 
 physical changes in these regions; and this, taken in con- 
 junction with the extinction of the mammalia and the evi- 
 dent amelioration in climate, bespeaks a vast antiquity 
 compared with the shell-mounds and pile-dwellings of 
 the preceding races. A vast antiquity ! but whether ten, 
 twelve, or twenty thousand years, we have in the mean 
 time no mode of precisely determining. 
 
 Physical changes proceed at rates too uncertain to con- 
 *stitute a scale of chronology, and we know too little of the 
 law of vital development to found upon the duration and 
 extinction of species. But if we may judge from existing 
 operations, and if we may estimate from the specific changes 
 in life now going on around us (and this with all the inter- 
 fering influences imposed by man), then the time must be 
 vast indeed since these primitive races were the inhabitants 
 of Southern and Western Europe. We do not contend, 
 like some, for thousands of centuries ; but we argue for 
 triple or quadruple the amount that has hitherto been as- 
 signed to human chronology. Let us look fairly at the 
 facts: the river -drifts, cave -earths, and lake -silts are, no 
 doubt, very ancient, but there is nothing connected there- 
 with that may not (computing by existing operations) have 
 been accomplished in ten or twelve thousand years. Again, 
 the mammoth, woolly rhinoceros, cave-lion, cave-bear, and 
 cave-hysena, are but species of existing genera ; and so little 
 do they vary in general character from those still living, 
 that their appearance at the present day would excite no 
 marvel. The whole aspects and surroundings of these ex- 
 
EXTINCT CONTEMPORARY MAMMALS. 285 
 
 tinct mammalia are in truth geologically recent; and when we 
 further consider the fresh condition in which some of them 
 occur in the ice -gravels of Siberia, we are compelled to 
 withhold from them an unlimited antiquity. It is a sound 
 maxim in paleontology, that the greater the divergence of 
 any species from existing species, the greater its antiquity ; 
 and founding on this rule, the mammoth, mastodon, and 
 their huge congeners, cannot lay claim to the vast antiquity 
 which many geologists have been so anxious to assign to 
 them. Still, with all these facts and allowances, it must 
 ever be remembered that the occurrence of hairy elephants 
 and woolly rhinoceroses in Western Europe bespeaks a 
 much colder climate than the present ; and as changes in 
 climate can only arise from great physical changes, great 
 alterations must have taken place in the external conditions 
 of our continent. Such changes are ever slow and gradual, 
 and thus we are compelled to admit a high antiquity to the 
 fashioners of these flint implements and their contempora- 
 ries, the mammoth and mastodon. 
 
 Indeed, the existence of a boreal climate necessitating 
 shaggy coverings for the elephant, and rhinoceros, would 
 seem to carry us back to times immediately post-glacial 
 that is, to the time when the last traces of the glacial 
 epoch were gradually being effaced by the advent of a 
 more genial and equable climate. Were this the case, 
 the appearance of man in Europe would be coeval with 
 the earlier Post-tertiaries, and his antiquity much higher 
 than the majority of geologists are yet prepared to ad- 
 mit. But his occurrence in Europe does not settle the 
 question of his first appearance on the globe. On the 
 contrary, the human race, in one or other of its varieties, 
 may have existed for ages in Asia or Africa before it 
 found its way to Western Europe, and, indeed, all that we 
 know of language and ethnology seems to point to this 
 
286 MAN'S PLACE IN THE GEOLOGICAL RECORD. 
 
 conclusion. Before we can arrive at the absolute anti- 
 quity of man, or of his real place in the Geological Eecord, 
 we must know more of the Asiatic and African Post-ter- 
 tiaries, and more of the correlation of these to the Post- 
 tertiary accumulations of Europe. We must also learn to 
 deal with man as with other fossil genera, and instead of 
 seeking for mere variations in skull and facial angle, we 
 must be prepared to admit variations that amount to true 
 specific distinctions. All animals in the history of the 
 past, if they have existed long enough, break into varieties 
 and species ; and it will be a proof of man's comparative 
 recentness, if we can discover no wider difference than mere 
 varieties ; but, on the contrary, it will be evidence of his 
 higher antiquity, if zoologists can show that any variation, 
 past or existing, is so great as to entitle it to be ranked 
 as a specific distinction. Man may be the sole species of a 
 single genus, but in this particular zoologists have departed 
 from the true Baconian method, and dealt with man as if 
 he did not belong to the same category of vitality with 
 which it is the duty of their science to deal ; and not till 
 they have learned to treat him from a natural-history point 
 of view, can we hope to receive from them anything like 
 truly philosophical opinion. 
 
 As the matter stands at present, we have evidence of 
 man's occupancy in Europe during the formation of the 
 earlier Post-tertiaries, and during the period when the rein- 
 deer, musk-ox, hairy elephant, and woolly rhinoceros 
 roamed over its surface. The existence of these animals in 
 Western Europe betokens a somewhat boreal climate, and 
 in all likelihood man gradually took possession of the 
 continent as the climate began to improve on the gradual 
 recession of the glacial epoch. Arranging the Post-tertiary 
 system, as has been proposed, into Mammothian, Rein- 
 deer, and Bovine stages, we find man occurring at least 
 
HIS FIRST APPEARANCE IN EUROPE. 287 
 
 during a portion of the Mammothian stage, and thus he- 
 speaking for him a vast and venerahle antiquity unex- 
 pressed in years, no douht, hut not on that account the 
 less certain in its existence and duration. But while man's 
 place in the geological record "belongs to the earlier Post- 
 tertiaries in Europe, older varieties of his race may have 
 existed for untold ages in the regions of Asia and Africa, 
 from which in all likelihood the European "branches were 
 descended.* On the advent of the glacial epoch over the 
 latitudes of Europe, the pre-glacial animals seem to have 
 receded to southern and more genial climates, and again on 
 its departure they appear, in some of their species, to have 
 returned to the old areas. It was during this post-glacial 
 return that man seems to have made his first appearance in 
 Europe a fisher and hunter, forming rude stone imple- 
 ments, and, so far as geology has discovered, very low in 
 the scale of civilisation. But while Mammothian man was 
 straggling along the river -hanks of Europe for a scanty 
 subsistence, other families of his race were in all proha- 
 
 * " It is not under the hard conditions of the glacial epoch in Europe," 
 says Dr Falconer, " that the earliest relics of the human race upon the 
 globe are to be sought. Like the Esquimaux, Tchukche, and Samoyeds 
 on the shores of the Icy Sea at the present day, man must have been 
 then and there an emigrant placed under circumstances of rigorous and 
 uncertain existence, unfavourable to the struggle of life and to the main- 
 tenance and spread of the species. It is rather in the great alluvial 
 valleys of tropical or sub-tropical rivers, like the Ganges, the Irrawaddy, 
 and the Nile, where we may expect to detect the vestiges of his earliest 
 abode. It is there where the necessaries of life are produced by nature 
 in the greatest variety and profusion, and obtained with the smallest 
 effort there where climate exacts the least protection against the 
 vicissitudes of the weather and there where the lower animals which 
 approach man nearest now exist, and where fossil remains turn up in 
 greatest variety and abundance. The earliest date to which man has as 
 yet been traced back in Europe, is probably but as yesterday in compa- 
 rison with the epoch at which he made his appearance in more favoured 
 regions." On the asserted occurrence of human bones in the ancient flu- 
 viatile deposits of the Nile and Ganges Quarterly Journal of Geology, 
 1865. 
 
288 MAN'S PLACE IN THE GEOLOGICAL RECORD. 
 
 bility we may almost say were undoubtedly enjoying a 
 higher civilisation in the sub-tropical and higher tropical 
 regions of Africa and Asia. Were these Asiatic races of 
 the same variety of our species as the Abbeville flint- 
 formers, or did they, though enjoying a higher degree of 
 civilisation, belong to some older but inferior variety 1 ? 
 Much, indeed, in the matter of man's antiquity will de- 
 pend upon how this question is answered by subsequent 
 discovery. If they belong to the same race, and there be 
 no indication of any inferior species of our kind, in ac- 
 cordance with the great law of animal development, then, 
 geologically speaking, man is of comparatively recent ori- 
 gin, and the question is narrowed to one or other of his 
 existing varieties. Our own opinion is that, granting a law 
 of development, the higher animals pass through fewer in- 
 termediate stages than the lower, and that, in man's case, 
 species more closely related to the Quadrumana are scarcely 
 to be expected. But while this may be true, it is equally 
 certain that if there be any truth in geological development 
 at all, the higher varieties must be more recent than the 
 lower; and thus the white variety of man more recent 
 than either the Eed Indian, the Negro, the Malay, or the 
 Mongol. And it is equally certain, according to any law 
 of development, that the older and lower varieties must 
 first pass away a fact in wonderful accordance with the 
 gradual disappearance of the coloured varieties before the 
 spread of the white variety of our kind. Here, then, we 
 have a twofold argument that may avail us in our re- 
 searches viz., the earlier appearance, and, conversely, the 
 earlier disappearance, of the lower varieties of a species ; 
 and applying this to man, the coloured varieties, which are 
 evidently inferior (whatever may be said to the contrary), 
 must have long preceded the white, just as now they are 
 passing away before it. 
 
VARIATION AS A TEST OF ANTIQUITY. 289 
 
 In this way we cany the antiquity of man high as it 
 may be in Europe to a still higher antiquity in the other 
 continents of the Old "World, and which must be geo- 
 logically investigated before any definite conclusion can 
 be arrived at either as regards time or developmental 
 descent.* The European men of the Bovine and Rein- 
 deer periods evidently belonged to the white or Caucasian 
 variety, but we have no certain evidence whether the 
 Abbeville flint-fashioners were of Caucasian, Mongolian, or 
 other variety. To whatever variety they belonged, they 
 were clearly of a date immediately post-glacial; though, 
 could it be shown by craniology that they were of other type 
 than the Caucasian, it would in our opinion be further proof 
 of their high antiquity. If we are to pursue the subject 
 of man's antiquity in Africa or Asia, this question of type 
 must constitute one of the main elements of determination, 
 for it would be outraging every principle in science to ap- 
 ply the test of variation and development to the other 
 orders of life, and shrink from applying it in the solitary 
 instance of man. Where we can prove by archaeological 
 means a high antiquity for man, let us adopt them ; where 
 we can show the same result by geological methods, let us 
 not neglect them ; but at the same time let us also value 
 those palaeontological doctrines of progression and develop- 
 ment which have thrown so much light on the order and 
 connection of vitality in general. If there be such a law of 
 progression, man must be as amenable to it as the rest of 
 creation, and whatever variation occurs in his race must be 
 taken, along with other elements, as a measure of time and 
 duration. We are aware that many geologists shrink from 
 
 * Since the above was written, we observe that implements of quartzite 
 have been discovered in the lateritic formation of Madras by Messrs Foote 
 and King of the Indian Geological Survey, thus opening the way to this 
 new and much desiderated line of evidence. 
 
290 MAN'S PLACE IN THE GEOLOGICAL EECORD. 
 
 this test of variation, and feel an uneasy tenderness when- 
 ever the question of man's descent becomes involved in 
 their researches and speculations. Truth, however, will 
 never "be attained by such weakness. In science, as in 
 morals, error becomes only more deeply rooted, and bigotry 
 more emboldened, the longer that honest conviction hesi- 
 tates, or gives to its beliefs a timid and uncertain utter- 
 ance. 
 
 Observe that, however man may have originated, it does 
 not alter his position in the scale of being. It is no degra- 
 dation to have been descended from some antecedent form of 
 life, any more than it is an exaltation to have been formed 
 directly from the dust of the earth. In the present state 
 of our knowledge it is even more difficult to conceive of an 
 origin from inorganic matter than of a development from 
 some pre-existing form. No one can compare with atten- 
 tion the vertebrate skeleton (of the mammals, for example) 
 without perceiving that it is adaptive modification that 
 runs throughout the whole of the ascensive orders, rather 
 than independent creation of newer and higher forms. In 
 his physical relations man is as much dependent upon 
 external conditions as the lowest creature with which he is 
 associated in the scheme of vitality. This scheme of vitality 
 is one united whole, from which you cannot possibly dis- 
 sociate any of its component parts ; and whatever be the 
 plan that has regulated the development of this scheme in 
 time, it must embrace man as certainly as it embraces all 
 or any of its other members. His high position depends 
 not so much upon the physical life which he shares in 
 common with other beings as upon his improvable intel- 
 lect ; and this, in any theory of his origin, can only be re- 
 solved into a newer and higher creational endowment the 
 latest manifestation in that Divine plan of cosmical pro- 
 gress which science is ever humbly and reverently endea- 
 
GENERAL REVIEW OF THE QUESTION. 291 
 
 vouring to reveal. "We accept the fact of this new endow- 
 ment ; shall we reject the continuity of progress through 
 which it has been evolved ? 
 
 Such are some of the reasonings that suggest themselves 
 in reviewing the question of " Man's Place in the Geologi- 
 cal Record." In the first place, let it be treated without 
 bias or predilection, as a matter of natural history and 
 geology. In the second place, let us avail ourselves of 
 all the evidence that history, archaeology, geology, and 
 palaeontology can supply. And in the third place, let us, 
 as true geologists, be wary in assigning dates in years and 
 centuries, while the whole superstructure of our science is 
 founded on a relative and not upon an absolute chronology. 
 Guided by these methods, it would appear that man has 
 been an inhabitant of Southern and Western Europe from 
 a time immediately succeeding the close of the glacial 
 epoch, and that in these regions his antiquity dates, if not 
 from the very earliest, at least from the earlier of the post- 
 tertiary formations. How long ago this may have been in 
 years and centuries, there is no condescension on the part 
 of legitimate geology; but clearly it is far, very far, beyond 
 the limits of the ordinarily received chronology of the 
 human race. But ancient as this may be, the implement- 
 bearing gravels, the cave-earths, the peat-mosses, shell- 
 mounds, and lake-dwellings of Europe cannot be taken as a 
 measure of antiquity for Asia, from which, as everything 
 tends to show, the first races of Europe were derived by the 
 ordinary means of natural dispersion and selection. And 
 even were the first appearance of the white or Caucasian 
 race geologically determined in Asia, the first appearance of 
 the coloured varieties (Mongol, Negro, Malay, &c.), each in 
 its own proper headquarters, would still remain a problem 
 of antecedent date, requiring similar methods of research, 
 
292 MAN'S PLACE IN THE GEOLOGICAL RECORD. 
 
 and similar processes of solution. In this way, and on the 
 fair presumption of the coloured and inferior being the 
 older varieties, the antiquity of man as a species mounts 
 still higher and higher, and the course of discovery may 
 yet compel us nay, will almost to a certainty compel us 
 to assign to him an origin coeval with the very dawn of 
 what we are in the habit of regarding as the Quater- 
 nary epoch, if not, indeed, with the close of the Tertiary 
 period, and just when the more gigantic fauna of that 
 era were passing away from the warmer zones of Asia, 
 Africa, and America. 
 
OEDEE AND SUCCESSION OF LIFE. 
 
 LIFE, ITS NATURE AND FUNCTION INTERDEPENDENCE OF PLANTS 
 AND ANIMALS HARMONY OF THEIR RELATIONS THEIR EXISTING 
 ASPECTS AND DISTRIBUTIONS ASPECTS AND DISTRIBUTIONS OF 
 THE PAST ADVANCE IN TIME FROM LOWER TO HIGHER FORMS 
 ORDER OF THIS PROGRESSION THEORIES OF LIFE-DEVELOPMENT 
 HOW FAR PROBABLE LAW OF CREATIONAL PROGRESS PROOFS 
 OF ITS EXISTENCE UNIVERSALITY OF ITS OPERATIONS ALIKE III 
 THE PHYSICAL, VITAL, AND INTELLECTUAL ITS ENDURANCE. 
 
 HOWEVER interesting it may be to trace the material changes 
 to which the crust of the earth has been subjected, this in- 
 terest falls infinitely short of that excited by the study of 
 the life-forms by which its surface has been successively 
 peopled. In the one case we know something of the forces 
 by which the changes are produced, and the modes in 
 which these forces operate ; in the other we perceive only 
 the external conditions under which plants and animals 
 exist, but we know nothing of the origin of Life, and as yet 
 very little of the causes concerned in the numerous varia- 
 tions and aspects it has assumed. In the one case we can, 
 to a certain extent, mould and modify the operating forces ; 
 in the other, vital action is altogether beyond our produc- 
 tion, and we can modify its variations only in the slightest 
 and most temporary degree. In the one case we have 
 masses that are operated upon from without ; in the other, 
 forms that are actuated by impulses from within, and, in 
 
294 ORDER AND SUCCESSION OP LIFE. 
 
 the higher animals at least, by the subtler promptings of 
 the intellect and reason. In the one case we deal with 
 forms and forces that are extraneous j in the other, with 
 those to which we ourselves belong, and hence the higher 
 the interest excited, and the deeper the mysteries involved. 
 What is life 1 Whence its origin ? And how has it mani- 
 fested itself during the long ages throughout which geology 
 has traced its presence in the rock-formations of the globe 1 
 These are questions of the highest interest to science, and 
 how feeble soever the indication towards a solution which 
 human knowledge can offer, every tracing is of value so 
 long as it is founded upon fact, and sketched by an honest 
 hand. Such is the aim of the present Sketch a deduction 
 from the statements in the preceding chapters, a digest of 
 the discoveries of palaeontology, an indication, if not of the 
 nature and relations of life, at least of its order and succes- 
 sion as warranted by the truths of Geology. 
 
 Concerning the origin of life, Geology ventures no opin- 
 ion. It may have started into being at the immediate 
 fiat of the Creator, or it may have arisen through secondary 
 causation, acting in obedience to Creative Law. It may 
 have sprung from a single primordial germ, or it may have 
 spread from several primordial sources. In its essence it 
 may be a thing per se, or it may be merely a manifestation 
 arising from the interactions of the subtler physical forces. 
 On such points Geology offers no opinion. It deals with 
 life as it finds it, and dates its commencement with the 
 earliest traces yet discovered in the stratified formations. 
 At one time this limit was found in the lower Silurians, 
 more lately in the Cambrians, and now, as we have seen in 
 Sketch No. 5, discovery has carried it back to the Lau- 
 rentian system a suite of strata of much higher antiquity. 
 Whether these Laurentian rocks are the oldest or earliest 
 in which traces of life can be detected, Geology does not 
 
ITS NATURE AND FUNCTION. 295 
 
 aver ; "but as the forms of vitality "become fewer and lower 
 in kind with, each successive remove in time, and as the 
 Laurentian forms are both very lowly in organisation and 
 scanty in number, inquirers are constrained to believe that 
 they are nearly approaching, if indeed they have not already 
 reached, the first beginnings of life on our planet. Be this 
 as it may, the earliest known forms of vitality occur in the 
 Laurentian system, and it seems something more than a 
 mere coincidence, that these forms should belong at the 
 same time to the very lowest orders that are known to 
 Zoology. Such is all we know of the commencement of 
 life on our globe ; such is the ultimate limit to which geo- 
 logical science has yet been enabled to push her investiga- 
 tions. But while this is incontrovertible as matter of fact, 
 we may believe and all analogy seems to favour the be- 
 lief that life was contemporaneous with the laying down 
 of the first-formed sediments. The external conditions 
 (light, heat, cold, rains, rivers, and seas) that favour the 
 one set of operations are usually those that accompany the 
 other ; and thus, wherever sedimentary strata occur, there 
 also may we expect to find traces of vegetable or animal 
 organisation. If the Laurentian be the earliest formed 
 strata, we have already reached the goal; should others 
 have existed before them, we can merely regard them 
 as the provisional commencement of that long line of 
 vital development which Geology is still labouring to 
 reveal. 
 
 But though ignorant of the origin and commencement of 
 life, we know something of its nature and functions. We 
 perceive that minerals increase by the accretion or external 
 addition of similar matter, but vegetables and animals grow 
 by the internal assimilation of substances which they 
 absorb and convert each into its own proper tissues. Once 
 formed, and the course of the mineral is completed; once 
 
296 ORDER AND SUCCESSION OF LIFE. 
 
 matured, and the plant or animal gives "birth to similar 
 plants and animals, and the course of reproduction may 
 endure for ages. Wherever heat, light, and moisture are 
 present, there life occurs, fitted partly for the air, partly for 
 the land, partly for the waters, and partly also for a para- 
 sitic existence, on and within the tissues of other plants 
 and animals. Unless under the extremes of heat and cold, 
 life is everywhere present, restricted, no doubt, to a thin 
 film of the globe measuring vertically, but spreading hori- 
 zontally over every belt of latitude, and enjoying, each 
 order according to its grade of organisation, the realisations 
 of growth and reproduction. We can imagine a material 
 world devoid of all manifestations of life, and such our 
 planet may have been during ages of which we have no geo- 
 logical indication ; but, constituted as it now is, its harmo- 
 nies would be incomplete without the presence both of 
 vegetable and animal existences. Not only is the presence 
 of the one necessary to the life of the other, but both are 
 indispensable to the consumption and reproduction of those 
 substances by which the structure and individuality of our 
 globe is maintained. The crust of our earth is a thing of 
 vegetable and animal as well as of mineral growth, and we 
 may be assured, that from the beginning it was contem- 
 plated that each should perform its part in the harmonious 
 maintenance of the whole. The mineral building up its 
 chemically composite structure, the plant disintegrating and 
 living upon these elements, the herbivorous animal feeding 
 upon the plant, the carnivorous animal upon the herbivor- 
 ous, the animal breathing the oxygen of the atmosphere and 
 exhaling carbonic acid, and the vegetable imbibing carbonic 
 acid and discharging in turn the oxygen, are but so many 
 stages in a cosmical succession as harmonious in its adjust- 
 ments as it seems interminable in its duration. Mineral, 
 vegetable, and animal, are evident co-adaptations of the 
 
GRADES OP ORGANISATION. 297 
 
 same great plan. "We may never know how they originate, 
 or why they exist, but we perceive the modes in which they 
 operate, and can determine the results of their harmonious 
 and incessant inter-actions. 
 
 At the present day we know that the great regulators of 
 plants and animals are heat, light, and moisture. Some are 
 adapted to the warmer regions of the globe, some to the 
 temperate, and others, again, to the colder latitudes. Some 
 are fitted for life on the dry land, some for life in the 
 waters ; while others, again, are fitted for both, or even to 
 wing their way through the atmosphere. Some affect the 
 marsh, while others cling to the thirsty upland ; some re- 
 joice in the shallow waters of the shore, while others find 
 their fitting habitat only in the deeper ocean. Some are 
 restricted to specific centres of limited extent, and present 
 little variation in character, while others enjoy a wider 
 range, and break into numerous and often widely divergent 
 varieties. Such are the obvious conditions and distributions 
 of life now, and such we may be certain were the nature of 
 its conditions and dispersion sduring all previous periods. 
 Again, some plants are rooted independently in the soil, 
 while others find their subsistence on other plants, or even 
 in animals. A vast number of animals live on vegetables, 
 while others prey on the vegetable-feeders, and are fitted 
 alone for this mode of existence. The tooth to tear is as 
 necessary as the tooth to grind, the foot to seize as the foot 
 to run, the hand to climb as the hand to hold, and the limb 
 to fly as the limb to walk or the limb to swim. Such are 
 the arrangements by which the balance and harmonies of 
 life are now sustained, and such we may presume were the 
 methods by which its harmonies were secured in former 
 ages. Plant-feeder and flesh-feeder, life and death, repro- 
 duction and decay, are necessary concomitants in the great 
 biological scheme of creation. ~VVe perceive them operating 
 
298 ORDER AND SUCCESSION OF LIFE, 
 
 in full force now ; palaeontology declares they were as uni- 
 versally energetic in bygone epochs. 
 
 Besides these obvious arrangements and inter-relations 
 of life, there is also grade or degree of organisation some 
 orders being more simple in structure and fitted for lower 
 functions, others being more complex and fitted for the 
 higher offices of vitality. The lichen incrusting the rock or 
 the sea- weed clustering the shelving reefs of the sea- shore, 
 and devoid of stem and leaf, is a lowlier organism than 
 the clubmoss or tree-fern ; and these again are less highly 
 organised than the true timber-tree, with its complex de- 
 velopment of trunk, branches, leaves, flowers, and fruits. 
 The sponge, rooted plant-like to the rock, is clearly a lower 
 phase of animal life than the coral or star-fish ; and these 
 again are less highly organised than the crabs and shell-fishes. 
 Animals like the star-fishes, crabs, and shell-fish, devoid of 
 backbone and bony skeleton (the Invertebrata\ are obvi- 
 ously lower in the scale of being than the fishes, reptiles, 
 birds, and mammalia (the Vertebrata); and even among 
 these vertebrates the cold-blooded water-breather is inferior 
 to the warm-blooded air-breather the fish on a lower stage 
 than the reptile, the reptile than the bird, and the bird 
 than the mammal. Still more, the marsupial or pouched 
 mammal, bringing forth immature young and carrying them 
 about for months, is less highly organised than the placen- 
 tal or true mammal, which gives birth to fully developed 
 young ; and among the true mammals themselves there are 
 manifestly various grades of organisation the whales are 
 lower than the ruminants, the ruminants than the carnivora, 
 the carnivora than the monkeys, and the monkeys than man. 
 And whatever may have been the abundance or develop- 
 ment of life during the geologic epochs, we may pre- 
 sume that such grades and distinctions have ever per- 
 vaded the whole vital scheme high and low, low and 
 
GEOLOGICAL EVIDENCES. 299 
 
 lower, being indispensable concomitants, then as now, ac- 
 cording to the field to be occupied and the function to be 
 performed. 
 
 But while there are, have been, and will continue to be such 
 distinctions and inter-relations of life, geology has unfolded 
 a new phase, unknown to, and unthought of by, our ances- 
 tors. To the earlier botanists and zoologists the existing 
 aspect of life seemed complete, and only such diversities 
 were acknowledged as those produced by station and habi- 
 tat in the various latitudes of the world. Kow, however, 
 geology has revealed by proofs innumerable and unmistak- 
 able that myriads of forms have ceased to exist, that as we 
 go backward in time these forms become more simple or 
 less highly organised, and that a period is at last reached 
 when our planet was peopled only by the very lowest forms 
 of vegetable and animal existence. The establishment of 
 this ascent in time from lower to higher forms is one of the 
 noblest triumphs of geology a revelation that has invested 
 the scheme of life with new significance, and imparted to 
 its study a higher and more enduring interest. How broad 
 the Scheme of Life when living and extinct are conjoined ; 
 how marvellous the inter-relations that subsist between its 
 innumerable and varied parts ; and yet how ceaselessly the 
 whole has ever been passing onward into newer and higher 
 manifestations ! "What has been the order of this ascent ? 
 Has it been regular and progressive ? Is the higher form 
 linked on to the lower by characters that are invariable and 
 discoverable 1 and if so, what seems to be the law that has 
 regulated this progression and development 1 ? Such are 
 some of the questions suggested by the consideration of 
 this ascent of life ; and as Geology has revealed the fact, it 
 may be legitimately allowed to attempt an explanation. 
 
 Assuming (and as yet we have no proof to the contrary) 
 that only the lowest or protozoan forms of life occur in the 
 
300 ORDER AND SUCCESSION OF LIFE. 
 
 Laurentian strata, it is admitted that we have an ascent to 
 corals, annelids, and Crustacea in the Cambrian, and to a 
 still higher and more abundant display of corals, star-fishes, 
 shell-fishes, annelids, and Crustacea in the Silurian. ISTot 
 only are the forms more numerous and varied, but at each 
 successive stage newer and higher orders come into view, 
 and we are compelled by evidence obtained from these early 
 systems, wherever they have been examined, to believe that 
 the march of life has been steadily onward and upward. 
 Up to this stage the living forms are wholly invertebrate 
 (that is, if we except a few doubtful instances in the upper 
 Silurians), and the plants chiefly sea- weeds and lycopods ; 
 but in the Old Red Sandstone ferns and coniferous frag- 
 ments are found, and fishes make their appearance in con- 
 siderable abundance. In the Carboniferous system, sea- 
 weeds, lycopods, ferns, equisetums, reeds, coniferous trees, 
 and numerous intermediate forms testify to a continuous 
 and gradual ascent in the flora ; while to a greater exuber- 
 ance of all the previous fauna is added the existence of 
 aquatic and terrestrial reptiles. In the earlier Secondary 
 rocks birds make their appearance, or at all events have not 
 been detected in more ancient strata; and in the upper 
 Secondaries, mammalian life of the marsupial orders begins 
 to manifest itself in increasing abundance. It is not till 
 we arrive at the Tertiary system that the higher mammals 
 occur ; and not till the Post-tertiary or Recent period that 
 we have any reliable evidence of the presence of Man, or of 
 his industrial operations. This progressive ascent in the 
 animal scale is accompanied by a similar advance in the 
 vegetable the palms and coniferse of the Secondary ages 
 being succeeded by the exogenous or true timber-trees of 
 the Tertiary, and these again by the timber-trees, fruits, and 
 cereals of the Current epoch. There may be imperfections 
 in the geological record districts unexamined, and fossil 
 
HYPOTHESES OP VITAL DEVELOPMENT. 301 
 
 forms yet undetected ; but the fact of this wonderful coin- 
 cidence of ascent in such large areas as Europe, North 
 America, and parts of South America, Asia, and Australia, 
 surely entitles the belief in a professional development of 
 life from lower to higher forms from thallogen to acrogen, 
 from acrogen to endogen, and from endogen to exogen;* 
 from invertebrate to vertebrate, from cold-blooded water- 
 breathers to warm-blooded air-breathers, and from simply 
 sentient existences to the higher activities of intellect and 
 reason. However complicated in detail, there can be no 
 gainsaying of this broad outline of ascent ; geologists may 
 differ in their interpretations of the means by which the 
 phenomena have been produced, but they cannot refuse as- 
 sent to the order in which they occur. Nor is it a mere 
 ascent in general terms from lower to higher classes, but 
 the orders, the genera, and the species partake of the same 
 progressional development this progression bearing a strik- 
 ing analogy to the order that prevails among the existing 
 grades of life, and in most instances also to the successive 
 stages of individual development. The forms, vegetable 
 and animal, of the Primary periods are on the whole lower, 
 more embryonic in aspect, and less specialised than the 
 forms of the Secondary, and these again less than those of 
 the Tertiary and Current epochs, t The ascent runs through 
 every ordinal group and section branching onwards and 
 upwards ; and is, we may rest assured, however little we 
 may perceive it, as operative now as during any of the by- 
 gone geological ages. 
 
 * See Schemes of Vegetable and Animal Classification in Sketch No. 7. 
 
 f " A progress from more generalised to more specialised structures " 
 (we quote Professor Owen, the most cautious, perhaps, of modern ana- 
 tomists), " analogous to that exemplified in the existing grades of animal 
 life and in successive phases of individual development, is appreciable 
 in the series of species which have succeeded one another upon our 
 planet." 
 
302 ORDER AND SUCCESSION OF LIFE. 
 
 As is well known to every reader of modern science, 
 various hypotheses have been advanced to account for this 
 progressive development of life as revealed by geology. Pro- 
 ceeding upon the assumption that the Scheme of Vitality 
 is one united whole, these hypotheses endeavour to show 
 that all the forms of plants and animals that have appeared 
 or will yet appear are but modifications by secondary means 
 of forms that had previously existed. Admitting that the 
 origin of life is beyond the grasp of science, they neverthe- 
 less seek to explain how the lowly forms of the Primary 
 periods were developed into the higher orders of the Sec- 
 ondary ages, and these again into the still higher orders of 
 the Tertiary and Current epochs. Perceiving that plants 
 and animals do undergo modifications and variations accord- 
 ing to climate, food, and geographical position, some would 
 ascribe the whole development and ascent which Geology 
 has revealed to the mere force of external conditions, oper- 
 ating through untold ages. Others, regarding this view as 
 inadequate, would seek to combine with the force of exter- 
 nal conditions the use and disuse of organs, by which any 
 organ habitually disused may become feeble, or altogether 
 disappear, while another organ by more varied use may be 
 increased or even transformed into an organ of altogether 
 different form and fitted for an altogether different purpose. 
 By these means, the plant originally formed for the waters 
 may become fitted for the marsh, and the plant of the marsh 
 adapted for growth and reproduction on dry land. And by 
 the same process the limb originally destined to swim may 
 be transformed into one fitted for walking, and the limb 
 for walking on land converted into one adapted for flight in 
 the atmosphere. Such changes as these, they contend, must 
 take place by almost imperceptible stages, and must require 
 long ages for their elaboration the newer qualities being 
 transmitted from generation to generation, and accelerated 
 
HYPOTHESES OF VITAL DEVELOPMENT. 303 
 
 during the embryonic state of each successive generation.* 
 Others, again, combine with these views the doctrine of 
 natural selection, by which, during the incessant changes 
 of geographical conditions, those varieties of plants and 
 animals best fitted for the new conditions will survive and 
 multiply, while those less adapted will gradually die out 
 and disappear. By such a process, these theorists contend, 
 such variations may go on till they amount to specific dis- 
 tinctions, and species themselves be converted into other 
 and higher genera. Perceiving that the ascent of life in 
 time that is, the ascent of life as shown by Geology co- 
 incides in a wonderful manner with the ascent from lower 
 to higher in living plants and animals, these hypothesists 
 admit the existence of a great creational plan, but seek to 
 explain its development through the operation of secondary 
 causes. Seeing that the physical phenomena of nature are 
 brought about by the operation of secondary causes, and 
 seeing that life is inseparably bound up with and de- 
 pendent on physical conditions, they seek to apply to the 
 one the same methods of research and reasoning which 
 
 * A little reflection will enable the non-scientific reader to perceive the 
 force of these arguments. The eyes of animals inhabiting dark caverns 
 gradually degenerate, and in course of generations become merely rudi- 
 mentary. The feet of ruminants habitually frequenting arid plains gra- 
 dually lose the digits that add to the resistance of the hoof on soft and 
 swampy ground. Wingless birds, like the apteryx and ostrich, while 
 they have lost the power of flight, apparently through disuse, acquire by 
 degrees greater size and strength of limbs. Certain structures which are 
 transitory and rudimental in existing species, are persistent and developed 
 in extinct. Thus, the heterocercal or unequally-lobed tail, universal in 
 palaeozoic fishes, is still found in the embryo state of existing fishes, which 
 have chiefly homocercal or equally-lobed tails. The tapering caudal ver- 
 tebrae which appear in the embryo or chick of modern birds, was persis- 
 tent and characteristic in mesozoic species like the Archceopteryx. These 
 and many similar facts well known to anatomists give foundation and re- 
 liability to these theories, and evidently point the way to the Law which 
 has regulated and still continues to regulate the development of organic 
 existences. 
 
304 ORDER AND SUCCESSION OF LIFE. 
 
 they apply to the other, and, philosophically speaking, there 
 is no other mode of approaching the question. "We must 
 deal with life as we find it, and however much science may 
 fail in its demonstration, it is bound at least to make the 
 attempt. In the present state of human knowledge, rea- 
 son may be unable to grasp all the subtle and multifarious 
 conditions that regulate the development of vitality on our 
 globe ; under a deeper and broader insight into nature's 
 operations, the truth may begin to dawn upon us, and all 
 the sooner and clearer the sooner and more earnestly we 
 commence the investigation. 
 
 Admitting the philosophy of the methods, we may still 
 be permitted to inquire how far any or all of these hypo- 
 theses are adequate to the solution of the problem ? In the 
 first place, it is obvious that external conditions operate 
 powerfully in the distribution of plants and animals, and 
 it is also admitted that they modify, in the long-run, the 
 species subjected to their operation; but it seems incredible 
 that they could transform one species into another species, 
 or one order into another order, without the aid of other 
 and more intimate physiological causes. Even combining 
 the force of external conditions with the use and disuse of 
 organs, and with the impulse of hereditary tendencies in 
 the embryonic or foetal stage of each successive generation, 
 the combination seems inadequate without some other factor 
 to keep the successive development in conformity with the 
 known plan of vitality. Should we add the operation of 
 natural selection, which is admittedly a powerful and ever- 
 active agent in the modification of species, still the questions 
 remain how plants and animals should exist in their 
 present ordinal arrangements, and how their appearance 
 in time should coincide, in the main, with these ordinal 
 arrangements 1 There are clearly some other factors over 
 and above all those which have yet been brought for- 
 
UNIVERSALITY OP CREATIONAL PROGRESS. 305 
 
 ward, to account for the plan of vital development ; some 
 physiological law for the general order of Life analogous to 
 that which governs the growth and development of the in- 
 dividual. The better, then, that we understand the physi- 
 ology of individual growth and varietal divergence the 
 fuller our knowledge of the palaeontological order and ascent 
 of vitality, the sooner will we be enabled to arrive at some 
 indication of this Law of progressional development. If 
 the teachings of geology are not a delusion, the fact of vital 
 progression on this globe is as certain as the succession of 
 its stratified formations. Science has already done much to 
 arrange and elucidate the one; may we not hope that under 
 the light of increasing knowledge and more philosophical 
 methods, human reason shall by-and-by attain to a satisfac- 
 tory explanation of the other 1 It is admitted that in course 
 of time, and under new conditions, plants and animals do 
 break into new varieties. Variation is thus merely a mat- 
 ter of time and continuance of condition. And if this be 
 admitted, we have only to discover in the respective species 
 those physiological peculiarities which give direction and 
 character to the new variations. Mysterious as the ordainings 
 of life may seem, the problem is manifestly bound up with 
 the operating forces of the universe, and as such is hope- 
 fully within the reach of science, as it is certainly within 
 its legitimate domain. All that we know of the growth, 
 reproduction, and decay of vitality are the results of physical 
 causation, which can be investigated and determined ; shall 
 we cease to believe that its development in time is similarly 
 produced and as capable of demonstration? 
 
 The outcry that has been raised in certain quarters 
 against these hypotheses of vital development, is utterly 
 senseless and unworthy. Investigators perceive that cer- 
 tain plans pervade the vegetable and animal kingdoms, 
 and that the whole is inseparably associated in one vital 
 
 u 
 
306 OBDER AND SUCCESSION OF LIFE. 
 
 scheme. They perceive that life is governed in its distri- 
 bution and existence by the operating forces of the uni- 
 verse ; they learn from* Geology that it has taken a certain 
 order of ascent in time, from lower to higher forms ; and 
 as students of nature, they endeavour to account for its 
 progression by appealing to the forces by which it is mani- 
 festly affected. Philosophically there is no other course 
 left to them. They must deal with life as they deal with 
 the other phenomena of the universe ; and human reason 
 is never more religiously occupied than when earnestly 
 striving to comprehend and account for the designs and 
 methods of the Creator. If there has been any irreverence 
 in dealing with this problem, that irreverence must rest 
 with those who would circumscribe the range of reason, 
 and seek, by unworthy clamour, to deter the human intel- 
 lect from rising to some conception, however faint, of the 
 laws by which the Creator has chosen to develop the 
 phenomena of His marvellous universe. The authors of 
 these hypotheses may be right, or they may be wrong, in 
 their views ; they may ascribe too much or too little to 
 certain agencies : but so long as they honestly endeavour 
 to arrive at the truth, their opinions ought to be gratefully 
 received and treated with candour. As students of science, 
 they abide by scientific methods ; and unless Life is to be 
 altogether removed from the category of Natural Science, 
 they have no alternative but to treat it in all its bearings 
 its rise, progress, and inter-relations as they would deal 
 with any other problem that comes within the scope of 
 their investigations. Higher than mere material pheno- 
 mena, more subtle in its relations than any physical 
 agency, more marvellous in its growth and reproduction 
 than any other department of nature, its comprehension, no 
 doubt, taxes the severest efforts of the human understand- 
 ing j but still, as portion of the universe, it partakes of all 
 
UNIVERSALITY OP CREATIONAL PROGRESS. 307 
 
 its progress, and must be amenable to all its laws. In this 
 view, Life is simply one of the great features of the uni- 
 verse, carried along with it through all its mutations, and 
 governed by the same great law of creational progression. 
 
 And this great law of creational progression is alike 
 operative in the material, vital, intellectual, and moral 
 phenomena of the universe. Nothing stands still. That 
 which has been will never occur again ; that which appears 
 now will assume a different aspect in the future. All the 
 former distributions of sea and land, with their various 
 surfaces, climates, and productions, have disappeared ; and 
 the existing distribution is as incessantly passing into 
 newer forms and aspects. All the phases of life which 
 Geology has revealed differ with each successive formation ; 
 higher succeeds lower at each advancing stage ; and the 
 present, we may rest assured, will be followed by a similar 
 progressional advancement. Man, too, in all his inter- 
 relations, is subject to the same all-pervading law. Physi- 
 cally, the lower variety has preceded the higher, and the 
 highest variety of the present day stands on a lower plat- 
 form than that which is destined to succeed it. Race after 
 race has risen from barbarism to higher and higher stages 
 of intellectualism and civilisation ; and in the moral world 
 clearer and purer views gain, age by age, a wider recogni- 
 tion and more general fulfilment. Nothing stands still; 
 truth alone is eternal ; and as the whole world, physical, 
 vital, intellectual, and moral, must partake of this progress, 
 truth itself will illuminate a broader field, and lead to 
 nobler and more godlike activities.* 
 
 * " In the lapse of ages, hypothetical^ invoked for the mutation of 
 specific distinctions," says Professor Owen, " I would remark that Man 
 is not likely to preserve his longer than contemporary species theirs. 
 Seeing the greater variety of influences to which he is subject, the 
 present characters of the human kind are likely to be sooner changed 
 than those of lower existing species. And with such change of specific 
 
308 ORDER AND SUCCESSION OP LIFE. 
 
 Such seems to have been and to be the destined order 
 and succession of vitality. As in existing plants and ani- 
 mals we perceive a vast variety of grades from lower to 
 higher forms, so throughout the development of Life in 
 time there has been a coincident ascent from the lower 
 to the higher ,orders. During the primary periods the 
 lands and waters were peopled only by the lowest forms ; 
 but as time rolled on, higher and higher orders gradually 
 made their appearance, each successive rock-system bearing 
 testimony to the introduction of newer and more highly 
 organised existences. Imperfect as the geological record 
 admittedly is, and limited as may be the portions of the 
 earth's crust yet examined, there is such a coincidence in 
 the fossil life of all the surveyed tracts, that we may 
 regard the order of ascent as an established fact, subject 
 only to minor modifications in the details. The differences 
 that have arisen ainong geologists relate not to the facts of 
 the ascent, but to the mode or modes in which the de- 
 velopment has been brought about. As we know more of 
 extinct life and more of the physiology of existing life, 
 these differences will in a great measure disappear, and 
 conflicting hypotheses give way to a uniform and satisfac- 
 tory theory. In the mean time every earnest endeavour 
 is entitled to our regard, and however startling its views, 
 or how little soever it may seem to clear the way to sounder 
 conclusions, it ought to be gratefully received as a contribu- 
 tion towards the solution of the highest and most interest- 
 ing problems, perhaps, that the progress of discovery has 
 submitted to the consideration of modern philosophy. 
 
 character, especially if it should be in the ascensive direction, there 
 might be associated powers of penetrating the problems of zoology, so 
 far transcending those of our present condition as to be equivalent to a 
 different and higher phase of intellectual action, resulting in what might 
 be termed another species of zoological science." Preface to Comparative 
 Anatomy and Physiology of Vertebrates. 
 
WHAT OF THE FUTUBE? 
 
 POSSIBILITY OF INDICATING THE FUTURE OF OUR PLANET OPINION 
 OF DR HUTTON EVERYTHING IN NATURE, PHYSICAL AND VITAL, 
 PASSING ON TO NEWER FORMS AND CONDITIONS NEW DISTRI- 
 BUTIONS OF SEA AND LAND NEW CLIMATES AND PHYSICAL 
 SURROUNDINGS NEW ARRANGEMENTS OF PLANTS AND ANIMALS 
 
 NEW DEVELOPMENTS, OR HIGHER AND HIGHER LIFE-FORMS 
 
 MAN SUBJECT TO THE SAME LAW OF PROGRESSION INFLUENCE 
 OF MAN ON THE FUTURE SLOW AND GRADUAL RATE OF NATURE'S 
 OPERATIONS EXALTED CONCEPTIONS OF THE UNIVERSE INSPIRED 
 BY THE BELIEF IN A LAW OF INCESSANT DEVELOPMENT AND 
 PROGRESS. 
 
 " MAN," says Dr Hutton in his celebrated < Theory/ " first 
 sees things upon the surface of the earth no otherwise than 
 the brute, who is made to act according to the mere im- 
 pulse of his sense and reason, without inquiring into what 
 had been the former state of things, or what will be the 
 future. But man does not continue in that state of ignor- 
 ance or insensibility to truth ; and there are few of those 
 who have the opportunity of enlightening their minds with 
 intellectual knowledge, that do not wish at some time or 
 another to be informed of what concerns the whole, and to 
 look into the transactions of time past, as well as to form 
 some judgment with regard to future events. It is only 
 from the examination of the present state of things that 
 judgments may be formed, in just reasoning, concerning 
 what had been transacted in a former period of time ; and 
 
310 WHAT OF THE FUTURE? 
 
 it is only by seeing what had been the regular course of 
 things that any knowledge can be formed of what is after- 
 wards to happen ; but, having observed with accuracy the 
 matter of fact, and having thus reasoned as we ought, with- 
 out supposition or misinformation, the result will be no 
 more precarious than any other subject of human under- 
 standing." No more precarious than any other subject, 
 and a great deal more certain, indeed, than most of the 
 topics with which the human understanding is apt to busy 
 itself ! Here is a world, Physical Geography informs us, 
 having certain ordainings at present ; here is a world, Geo- 
 logy informs us, which has had a strange and varied history 
 in the past ; and combining our knowledge of past and 
 present, with faith in the uniformity of nature's operations, 
 we are surely entitled to speculate with some degree of cer- 
 tainty as to the fate that awaits it in the future. Such spec- 
 ulation forms the subject of the present Sketch, and guided 
 by the spirit of the Huttonian philosophy as above ex- 
 pressed, we do not despair of arriving at something like an 
 intelligible indication. This indication may not exactly 
 carry us forward to positive appearances, but it will show 
 us, at least, what cannot continue, and thus the better pre- 
 pare us for the perception and admission of the changes 
 that must follow. Xo doubt, the changes in the natural 
 world are so multiform and complex, and their producing 
 causes act and react so unequally upon each other, that 
 man, limited in his faculties and imperfect in his know- 
 ledge, can never hope to forecast either their exact order 
 or amount; still, by adhering to right methods, he can 
 sketch an outline of the future, just as he has been enabled 
 to trace the vestiges of the past, and this outline, shadowy 
 as it may be, is something at least for Geology to boast of. 
 It is true that it will add no new fact to our knowledge, 
 for facts are things that have been accomplished; but its 
 
NEW DISTRIBUTIONS OP SEA AND LAND. 311 
 
 tracing gratifies the intellect, and the belief in its cer- 
 tainty exalts our conceptions of the course and continuity 
 of creation. 
 
 And, first, we may safely assert that the present distribu- 
 tion of sea and land, with all its diversity of continent and 
 island, will not be the prevailing arrangement in future 
 ages ; and that the more remote the period, the greater in 
 all likelihood the difference. All that Geology teaches of 
 the past, shows that sea and land have repeatedly changed 
 places; all that Physical Geography tells of the present, 
 declares that similar changes are incessantly in progress. 
 Every wind that blows, every frost that freezes, every shower 
 that falls, river that runs, and wave that strikes, is wast- 
 ing and wearing down the framework of the existing con- 
 tinents ; and the eroded material, borne down to lakes and 
 estuaries and seas, is gradually displacing so much of the 
 water and creating newer lands. This waste is so apparent 
 on every cliff, and on every ravine and river-glen, that its 
 truth requires no further enforcement ; and the same holds 
 good of every shore against which the waves dash, or the 
 tidal currents scour. But while loss goes forward in one 
 region, gain takes place in another ; and thus most of our 
 river plains are but the sites of silted-up lakes, just as all 
 our deltas, occupying millions of square miles, are recent 
 and still progressing acquirements from the sea. Nor is it 
 alone to forces from without that the surface of our earth is 
 subjected. The forces from within the volcano, earth- 
 quake, and crust-motions, described in Sketch No. 3 are 
 equally active and incessant; here piling up new hills, 
 there throwing up the sea-bed into dry land, and here, 
 again, submerging terrestrial surfaces beneath the waters of 
 the ocean. If, then, such changes are unmistakably taking 
 place at the present day, and if by a parity of reasoning 
 
312 - WHAT OF THE FUTURE? 
 
 we can show that kindred changes took place in times past, 
 we are surely entitled to rely on the uniformity of nature's 
 operation, and to believe that similar changes will continue 
 to "be effected. The conclusion is irresistible, and thus 
 must be admitted the truth of our first proposition, that the 
 future distributions of sea and land must differ from the 
 present, and that as time rolls on the divergence will be- 
 come greater and greater, till all the existing continents 
 disappear, and new ones arise, with other contours, other 
 surfaces, and other climates, but all fluctuating and progres- 
 sive as those that went before. The whole history of the 
 past, as interpreted by Geology, has been one incessant 
 round of terraqueous change ; the forces of nature are still 
 as active and unabated in operation; and the inevitable 
 results must be a round of terraqueous changes in the 
 future, as incessant in their recurrence and as extensive 
 in their range. 
 
 In the second nplace, it is equally clear that if the lands 
 of the current era are gradually disappearing, and newer 
 ones as gradually in course of formation, the latter must 
 occupy different positions on the earth's surface, and as a 
 consequence, must enjoy different climates and different 
 geographical surroundings. They may be more continental 
 or more insular, more tropical, more temperate, or more 
 arctic ; but however this may be, it is quite evident they 
 must differ in these respects from the existing. In ignor- 
 ance of the law which regulates the great crust-motions of 
 the globe those slow upheavals and submergences of ex- 
 tensive tracts we can scarcely indicate the position of the 
 lands that will immediately succeed the existing ; though, 
 judging from the directions of most of the great delta-form- 
 ing rivers, it would seem that they will lie more within the 
 warmer zones of the globe. The great rivers of the New 
 
FUTURE POSITIONS OP 
 
 World the Mississippi, Orinocco, Amazon, and 
 are all projecting their vast deltas within these warmer 
 zones ; so also are the larger rivers of Europe and Africa, 
 for though the Nile has a northerly trend, its delta is still 
 within these warmer limits ; and so also are the more im- 
 portant delta-formers of Asia the Tigris and Euphrates, the 
 Indus, Ganges, Irawaddy, Menam, Kong, Yang-tse-Kiang, 
 and Hoang-ho. One has only to cast his eye over a map 
 of the " river-systems," to perceive the truth of this asser- 
 tion; for though Siberia and Arctic America are also pos- 
 sessed of large rivers, their ice-bound character and other 
 conditions render their laniforming powers comparatively 
 unimportant. To this southerly projection of the great 
 rivers must also be added the fact, that vulcanic agency 
 is much more active in its accumulations within tropical 
 and sub -tropical than within arctic or antarctic zones. 
 Appeal to any volcanic map of the world, and see how 
 blank and quiescent are the great tracts of North America, 
 Northern Europe, and Northern Asia, as compared with 
 the warmer and more southerly zones, and then judge how 
 much this may have to do with the formation and disposi- 
 tion of the future continents. In all the formations of 
 newer lands vulcanicity has played an essential part ; can 
 we fail to infer that the vast cincture of volcanic action 
 that surrounds the Pacific, as well as the numerous centres 
 that stud its basin, are intimately connected with the ela- 
 boration of future land-masses within its area ? It is true 
 that the gradual elevation noted by voyagers among the 
 Arctic Islands, Northern Greenland, Spitzbergen, Scan- 
 dinavia, and Siberia, would seem to point to a more con- 
 tinuous massing of the land in that direction ; but though 
 this were to be the case, it would not interfere with the 
 likelihood of our previous surmise, that the dry lands more 
 immediately succeeding the existing will lie within more 
 
314 WHAT OF THE FUTURE? 
 
 southerly and warmer latitudes. But the mere lying 
 within more southerly latitudes does not altogether de- 
 termine the nature of a climate or the geniality of external 
 conditions. Insular or continental arrangement of the land- 
 masses, altitude above the sea-level, the direction of moun- 
 tain-ranges and valleys, the amount of rainfall, and the set 
 of ocean-currents from colder or warmer regions, all influence 
 less or more the climate of a country ; and these, as affecting 
 the future lands of our globe, we have no means whatever 
 even of guessing at. All that we know for certain is, that 
 the existing continents are gradually passing into newer 
 forms and dispositions, and that these dispositions must 
 of necessity be accompanied by other climates and by other 
 vegetable and animal appointments. All that we can offer 
 as a legitimate geological inference is, that the land-masses 
 more immediately succeeding the existing will be more sub- 
 tropical and tropical in their position, and, cceteris paribus, 
 more congenial in their physical surroundings. 
 
 In the third place, if the present continents and islands 
 are to be superseded by others possessed of different ex- 
 ternal conditions, it follows that these newer lands must be 
 characterised by different distributions of plants and animals. 
 At present it is presumed that each plant and animal oc- 
 cupies the station and habitat best suited to its growth and 
 perfection ; but if these situations be interfered with, no 
 matter how slowly, certain races must succumb to the change, 
 while others will usurp their places. Were the future con- 
 tinents, for example, to be gradually evolved within lower 
 latitudes, their flora and fauna would as gradually assume 
 a tropical aspect existing forms, on the other hand, dis- 
 appearing stage by stage with the external conditions to 
 which they had been originally adapted. The disposition 
 of the existing continents is mainly longitudinal, hence they 
 
NEW CLIMATES AND LIFE DISTRIBUTIONS. 315 
 
 are subjected to extreme diversity of climate, and conse- 
 quent variety of vegetable and animal life ; were the lands 
 of the future to be arranged more latitudinally, a greater 
 uniformity of climate would prevail, and with this uni- 
 formity a corresponding sameness in the specific distribution 
 of vitality. The existing land-masses bulk most largely in 
 the northern hemisphere ; we can readily perceive how dif- 
 ferent the climatic and vital arrangements of the globe 
 were they mainly disposed in the southern. The trade- 
 winds, tides, and oceanic currents the great modifiers of 
 climate are interrupted in their normal continuity by the 
 longitudinal disposition of the existing continents, and 
 thrown into minor and complex deviations ; how different 
 the result did the disposition of the land permit them to 
 revolve in simple and unbroken continuity ! On the whole, 
 it may be safely assumed, that the greater the difference be- 
 tween future and existing continents in position and climate, 
 the greater will be the difference in their vital appointments; 
 and thus the future, from those physical causes alone, would 
 present a totally different life-picture from the present. 
 There might be no new creations nor developments, but 
 there would be extensive re-arrangements and re-assortments 
 of the existing extermination of certain genera and species 
 and increase of others, and along with these a corresponding 
 redistribution of the varieties of the human family itself. 
 We have said " there might be no new creations nor de- 
 velopments," and yet it is difficult to conceive of any exten- 
 sive alterations in the distribution of sea and land, without 
 associating with them newer phases of vegetable and animal 
 existence. In the history of the past, new developments of 
 life are so intimately associated with geographical changes, 
 and every newer formation so distinctively characterised by 
 its own peculiar and higher species, that whatever the law 
 by which the succession of vitality on our globe is gov- 
 
316 WHAT OP THE FUTURE? 
 
 erned, external conditions are undoubtedly one of its prin- 
 cipal factors ; and thus, with other distributions of sea 
 and land, we may anticipate not only other distributions, 
 but other and newer phases of their flora and fauna. 
 
 But, fourthly, if we are to be guided in our speculations 
 respecting the future by our knowledge of the past, another 
 and more important element comes to be considered, and 
 that is, the continuous ascent from lower to higher life- 
 forms which is traceable throughout the whole of the geo- 
 logical periods. If there has been such an ascent through- 
 out the past by some process of development, or whatever 
 it may be, the reasonable presumption is, that the same 
 process will continue to manifest itself in the future. It is 
 by no means asserted that investigators have anything like 
 completed the geological record; but all that has been done, 
 whether in Europe, Asia, America, or Australia, tends to 
 the establishment of an ascent in the main from the cryp- 
 togam to the phanerogam, from the invertebrate to the ver- 
 tebrate ; from the endogen to the exogen, from the fish to 
 the reptile, from the reptile to the bird, and from the bird 
 to the mammal. Even within these great sections there 
 has been a corresponding ordinal advance j and although 
 new discoveries occasionally compel us to modify our views 
 as to the time when certain orders and genera made their 
 first appearance, still no discovery has ever been made that 
 militates in the least against the general doctrine, that the 
 more lowly organised have regularly preceded the higher 
 and more specialised orders. We say " regularly preceded," 
 for though systematists are occasionally puzzled with appar- 
 ent breaks in the continuity, these breaks are either the 
 result of local obliterations, or they arise from limited and 
 imperfect observation. Such having been the progressive 
 evolution of life during the long and physically-varying 
 
HIGHER PLANTS AND ANIMALS. 317 
 
 cycles of the past, the geologist is surely entitled to pre- 
 sume that a similar evolution will continue to mark the 
 onward course of creation. 
 
 It is true, it may be argued, and indeed has been argued, 
 that the system of Life has culminated in the present 
 epoch, and is, consequently, subject to no further develop- 
 ment; and if it has not so culminated, that new races ought 
 now and then to be making their appearance. Such rea- 
 soning, however, is altogether at variance with the slow 
 and gradual evolution of events as impressively taught by 
 Geology. During the past, well-defined genera and orders 
 make their appearance only after the lapse of ages; and two 
 thousand or twenty thousand years of the current epoch 
 may be too short a period for the full development of new 
 and higher races. All that seems necessary for our argu- 
 ment is, that physiology can prove a tendency to variations 
 in existing genera and species ; and if such a tendency can 
 be demonstrated, no matter how slight and slow, the widest 
 subsequent divergence, even to the extent of new families 
 and orders, is only a question of time and continuation. 
 This is all that Geology contends for; and surely the varia- 
 tions in plants and animals which are continually taking 
 place under change of external condition, and under the in- 
 fluence of culture and domestication, must be sufficient to 
 convince every mind capable of ordinary reasoning, that 
 the susceptibility to newer developments is a quality as 
 operative now as during any of the former epochs. It is 
 vain to argue that no introduction of newer forms has been 
 witnessed during the last three or four thousand years of 
 human history. It is little more than half a century since 
 such questions began to attract the attention of philoso- 
 phers ; and all that went before erroneous notions of nat- 
 ural history, limited acquaintance with the geography of 
 the world, ignorance of geology, and total absence of all 
 
318 WHAT OF THE FUTURE? 
 
 reliable record renders any arguments founded on this 
 ground utterly idle and worthless. If vast physical changes 
 have passed unmarked by our ancestors, what marvel need 
 there be that the minuter phenomena of vital variations 
 should have wholly escaped their attention 1 If the varia- 
 tions, descent, and dispersion of the human family be a 
 matter of doubt and uncertainty to historians and ethnolo- 
 gists, what marvel need there be that the varieties, descent, 
 and dispersion of the lower races should have passed un- 
 noticed and even unsuspected 1 But if the introduction of 
 new genera and species cannot be positively proven, we 
 know that numerous forms have disappeared from certain 
 localities, and that several (the dinornis, sepiornis, dodo, 
 solitaire, great auk, rhytina, &c.), within a comparatively 
 recent period, have become altogether extinct. As extinc- 
 tion and creation ever went side by side in the past, so the 
 fair presumption is that extinction is attended by a similar 
 creation in the present. The minutest scrutiny can detect 
 no decay in the physical accompaniments of life, no decline 
 in the powers of vitality itself, and no change whatever 
 in any of its discoverable relations to external nature ; 
 and surely on these, as on all the grounds formerly men- 
 tioned, we are entitled to believe in a continuance of vital 
 development, as firmly as in a continuance of the physical 
 changes which are daily and hourly taking place around 
 us. The one may be less perceptible than the other, but 
 not on that account the less real ; slower in their rate of 
 progress, but not the less certain and continuous. 
 
 Such a progression being granted, the Life of the future 
 must differ from that of the present, as that of the pre- 
 sent differs from all that went before. Old genera and 
 species must pass away, and newer and higher ones take 
 their places. As the ratio of development among the dif- 
 ferent classes and orders, both of plants and animals, seems 
 
HIGHER PLANTS AND ANIMALS. 319 
 
 to have differed during the past the lower being more per- 
 sistent, or less variable, than the higher so the same ratio 
 will manifest itself in the future, the more highly organised 
 passing by more rapid stages into newer and higher forms. 
 Within the same limit of time the invertebrate may un- 
 dergo less modification than the vertebrate, the aquatic less 
 than the terrestrial, and the cold-blooded less than the 
 warm-blooded ; but all (by whatever process) must sooner 
 or later pass into newer and higher forms, and man himself 
 as certainly as the plants and animals that form the theme 
 of his deliberations. If there exist a great Law of Progres- 
 sion and all that palaeontology has revealed of the past or 
 physiology taught of the present points to such an ordain- 
 ing it would be reversing our ordinary ideas of the per- 
 manence of nature to suppose such progression had come 
 to an end when all its accompaniments and all the media 
 through which it manifests itself remain unimpaired and 
 persistent. And it would be equally at variance with all 
 philosophical notions of natural history to suppose that a 
 law which had operated alike on all the orders of life in the 
 past would become partial and exempting in the present. 
 It may startle some minds to hear the same argument ap- 
 plied to man as to the rest of the animate creation. The 
 reverse, unfortunately, has been too long the fashion. The 
 interests of science, as well as the sacredness of truth, demand, 
 however, that where nature operates alike the student of 
 nature shall not venture to obtrude with artificial " schemes 
 of arrangement," and "lines of demarcation." Looking at 
 it merely as a question of natural history and this, be it 
 observed, is the only way in which science can approach it 
 the future of the human race must be subject to the 
 same laws of variation and progression as those which have 
 governed and still continue to govern the extinctions and 
 evolutions of the other orders of vitality. The rate of 
 
320 WHAT OF THE FUTURE? 
 
 variation may differ in the respective orders, but from the 
 law of variation there can be no possible exemption. And 
 if this rate of variation has hitherto been more rapid in the 
 higher than in the lower orders, the existing varieties of 
 man must consequently the sooner pass into other and 
 higher varieties. 
 
 In the last place, a new and important element must 
 ever be taken into account in all our reasonings respecting 
 the future flora and fauna of the globe. During the old 
 geological epochs the " Law of Development," or whatever 
 else it may be termed, exerted itself universally, and this 
 without control or interference by human operations. 
 Now, however, and during the current epoch, man comes 
 in as a modifying and sub-creative agent here removing 
 and extirpating, there transferring and multiplying, and 
 this the more signally the more settled and civilised he be- 
 comes. Observe what changes must have taken place since 
 civilised man first took possession of Asia and Europe, and 
 how much more since, under the impulse of modern pro- 
 gress, he has carried his efforts to America and Australia ! 
 The natural flora of a region must make way for his culti- 
 vated plants, and the fauna for his domesticated animals. 
 Here he reclaims and extirpates, and this extirpation reacts 
 in a hundred ways on the surrounding fauna. There he 
 transfers and acclimatises, and in a few generations the 
 plants and animals of the Old World flourish and multiply 
 in the New, and by reciprocation those of the New World 
 become equally prolific in the Old. Here he destroys the 
 plant, and the animal deprived of its food shifts ground or 
 dies out ; there he introduces a new animal, and, in the 
 struggle for existence, some weaker and less elastic species 
 succumbs before the intruder. Of course, there are great 
 climatal limits to this transference, which the utmost inge- 
 
GENERAL RETROSPECT. 321 
 
 nuity of man cannot pass, but there is no possible end to 
 his extirpations and modifications; and thus in the lapse of 
 time the natural course of vital development and distribu- 
 tion will be extensively interfered with by the operations 
 of man. But extensive as may be his interference, he can- 
 not overrule the great Law of Progression any more than he 
 can prevent the physical operations by which the continents 
 themselves are continually modified. The law will go irre- 
 sistibly forward, carrying man in his several varieties along 
 with it ; employing, it may be, his influence as a pre-ordain- 
 ed portion of its operations, but still methodically ascending 
 from higher to higher, till the future aspects of life differ as 
 widely from those of the present, as its present aspects differ 
 from those that preceded. 
 
 Such are the leading features of the future, which, rea- 
 soning from the order of the past and the appointments of 
 the present, Geology is enabled to indicate new distribu- 
 tions of sea and land, new climates and physical surround- 
 ings, new and higher orders of plants and animals ; but 
 all these brought about so slowly and gradually that the 
 changes become apparent only after the lapse of ages. The 
 present, so far as we can judge, is as fluctuating as the past, 
 and yet the oldest scenes of human history India, Meso- 
 potamia, the valley of the Nile, the shores of the Levant, 
 Greece, and Italy remain in all their broader features 
 much as they were three thousand, four thousand, and six 
 thousand years ago. So tranquil, indeed, are the great 
 physical progressions of nature that it requires some mental 
 effort to perceive them ; so gradual the vital, and through 
 so many intermediate stages, that it demands an exercise of 
 reason to admit their reality. But when once perceived, 
 how enlarged our conceptions of the universe a system of 
 incessant fluctuation and progress in its details ; a system 
 
 x 
 
322 WHAT OF THE FUTURE? 
 
 of stability and permanence in its general appointments ! 
 To the ignorant mind, alluded to by Dr Hutton in our open- 
 ing quotation, the earth is a mere monotonous panorama 
 of birth, progress, and decay the same now as it has been 
 from the beginning, and as it is now so to continue un- 
 changed and unchangeable to the end. To the enlightened 
 mind, on the other hand, it becomes a scene of incessant 
 development and progress multiform and variable in its 
 physical relations, diversified and progressive in its vital 
 appointments, and still at every turn assuming more won- 
 derful and more exalted aspects. How much more en- 
 nobling this conviction of our planet's incessant mutation 
 and progress than the old belief in its stereotyped same- 
 ness and ever-threatened decay ! How enlarged the con- 
 ceptions of Creative Wisdom inspired by a knowledge of 
 these ever-varying and ever-advancing aspects these end- 
 less adaptations and boundless resources ! And how much 
 more when we carry our views from this world of ours to 
 the other members of the planetary brotherhood, and be- 
 lieve them subject to similar laws, and characterised by 
 similar appointments ! To the eye of sense they are mere 
 balls swinging clearly and coldly in space j to the eye of 
 enlightened reason they become, like their sister orb, multi- 
 form in the details of their terraqueous surfaces, variable in 
 their physical and vital aspects, and yet throughout all 
 their variability invariably conforming to a higher law of 
 development and progress. 
 
INDEX. 
 
 ABBEVILLE flints and flint-formers, 284. 
 .fEpiornLs, extinction of, in Madagascar, 
 
 Agassiz, " monograph of fossil fishes," 
 
 Agents modifying the earth's crust, 38. 
 " Age of mammals," the, 207. 
 " Age of reptiles," the, 193. 
 Amber, its relation to lignitic beds, 
 
 211. 
 
 Ammonites of secondary systems, 193. 
 Animals and plants of the future, 316. 
 Animals, systematic classification of. 
 
 124. 
 
 Anthracites as distinguished from bitu- 
 minous coals, 153. 
 Antiquity of man, relative not absolute, 
 
 284. 
 
 Antiquity, relative, of rock-deposits, 85. 
 Aqueous agencies, their operations, 40. 
 Archteopteryx, or fossil bird of oolite, 
 
 196. 
 Atmospheric agencies, their operations, 
 
 38. 
 
 Atmospheric denudation, effects of, 53. 
 Auk, great, probable extinction of , 271. 
 Avalanches, formation and varieties of, 
 
 219. 
 Azoic rocks, definition of, 97. 
 
 Barrier reef of New Holland, 265. 
 Basins, tertiary, illustrations of, 204. 
 Beaches, raised, or ancient sea-margins, 
 
 260. 
 
 Bergrap, the, of Norway, 217. 
 Bird-life of secondary periods, 195. 
 Bone-shoals and osseous breccias, 265. 
 Boue, his description of glaciers, 222. 
 Boulder clay or lower " till," 234. 
 Bovine period in European geology, 
 
 286. 
 
 Bovine stage of post-tertiary epoch, 286. 
 Brick-clays of the glacial period, 238. 
 Britain's mechanical supremacy, and 
 
 her coal-fields, 177. 
 
 Bronze, stone, and iron ages, relative 
 
 antiquities of, 279. 
 
 Brown-coals or lignites, nature of, 167. 
 Browne on ice-caverns, quoted, 223. 
 Burrh- stone of tertiary formations, 
 
 211. 
 
 Cainozoic formations, definition of, 26, 
 29. 
 
 Calc-tufa and calc-sinter, 262. 
 
 Cambrian system, its rocks and fossils, 
 91. 
 
 Cannel or parrot coal, 154. 
 
 Carboniferous or coal-period vegeta- 
 tion, 167. 
 
 Carboniferous period, its probable phy- 
 sical conditions, 170. 
 
 Carboniferous system, subdivisions of, 
 161. 
 
 Carses of Scotland, their formation, 
 256. 
 
 Cave-bear, extinction of, in Europe, 
 270. 
 
 Cave-earths and cave-dwellers of Eu- 
 rope, 283. 
 
 Cave-lion, extinction of, in Europe, 
 270. 
 
 Cephalaspis, old red sandstone fish, 
 
 Chalk or cretaceous system, its com- 
 position, 190. 
 
 Chambered shells of secondary ages, 
 193. 
 
 Chemical action, metamorphic effects 
 of, 71. 
 
 Chemical agencies, their operations, 42. 
 
 Chronological arrangement of rock-^ 
 formations, 29. 
 
 Chronology of geology, relative nature 
 of, 273. 
 
 Chronology of rock-formations, how 
 determined, 26. 
 
 Classification of rock-formations, 29. <-"" 
 
 Cleveland ironstone district, 199. 
 
 Climate, periodical oscillations of, 215. 
 
324 
 
 INDEX. 
 
 Climatic character of the future land 
 
 masses, 314. 
 Coal, ancient and recent use of, 156. 
 
 COAL AND COAL-FORMATIONS, 143-158. 
 
 Coal, chemical composition of, 153. 
 
 Coal family, arrangement of, 145, 153. 
 
 Coal, its applications and importance, 
 178. 
 
 Coal, nature and formation of, 150, 151. 
 
 Coal-fields of America, &c., 175. 
 
 Coal-fields of Britain, their value and 
 accessibility, 185. 
 
 Coal-fields of Britain, probable dura- 
 tion of, 174. 
 
 Coal-measures, flora of, 167. 
 
 Coal-measures, their economic value, 
 173. 
 
 Coals of the oolitic system, 148, 149. 
 
 Coals of the secondary systems, 148. 
 
 Coccosteus, fish of the old red sand- 
 stone, 138. 
 
 Colossochelys, fossil turtle of India. 
 208. 
 
 Cones, volcanic, varieties of, 52. 
 V Conglomerates, formation of, 71, 72. 
 
 Continents, position of the future, 312. 
 
 Coral-growths, geological results of, 44. 
 ->XDoral-reefs, their nature and formation, 
 264. 
 
 Crannoges of Ireland and Scotland, 
 254. 
 
 Craters, central and lateral, 52. 
 
 Creational progression, law of, 307. 
 
 Cretaceous or chalk system, 189. 
 
 Crevasses in glaciers, 221. 
 
 Crust motions, nature and ope'rations 
 of, 57. 
 
 Crust of the globe, meaning of, 18, 
 
 CRUST, THE, WE DWELL UPON, 17-34. 
 
 Crustacea of the old red sandstone, 136. 
 
 Crustacean tracks on old red sandstone 
 strata, 132. 
 
 Currents, oceanic, geological effects of, 
 41. 
 
 Cuvier's law of co-relation of parts, 115. 
 
 Cycads of secondary formations, 197. 
 
 Dayman's (Captain) soundings of the 
 
 Atlantic, 259. 
 Deductions from study of the earth's 
 
 crust, 30. 
 Denudation, effects of, on mountain 
 
 ranges, 54. 
 Development, law of, relating to man. 
 
 290. 
 
 Development, vital, theories of, 302. 
 Developmental progression, idea of, 
 
 how originating, 301. 
 Devonian, nature and limits of its 
 
 strata, 135. 
 Diatomaceous accumulations, extent 
 
 of, 266. 
 
 Diluvium or diluvial drift, 239. 
 Dinornis, extinction of, in New Zea- 
 land, 271. 
 Dinosaurus, huge secondary reptile,195. 
 
 Diplacanthus, spiny fish of old red 
 sandstone, 138. 
 
 Diprotodon, tertiary marsupial of Aus- 
 tralia, 208. 
 
 Dirt-bed or fossil soil of Portland, 197. 
 
 Distribution of land and water in the 
 future, 311. 
 
 Dodo, extinction of, in Mauritius, 271. 
 
 Dressings.glacial, on rock surfaces, 235. 
 
 Drifts from river action, 252. 
 
 Dura Den, its fossil fish-beds, 137. 
 
 Earth-crust, deductions from its study, 
 
 Earth's crust, composition of, 21. 
 Earth's crust, how sustained, 48. 
 Earthquakes, nature and operations 
 
 of, 53. 
 
 Earthquake-waves, nature of, 56. 
 Eocene tertiaries, definition of, 203. 
 Eozoic formations, definition of, 26, 
 
 29. 
 
 Eozoon Canadense, animal nature of, 89. 
 Erratic block-group of glacial epoch, 
 
 Estuarine formations of current era, 
 255. 
 
 Estuarine formations, their composi- 
 tion, 257. 
 
 Eurypterus, crustacean of the old red, 
 136. 
 
 Falconer, Dr, on antiquity of man, 287. 
 Fauna of the carboniferous era, 168. 
 Fens of Lincolnshire, 258. 
 Ferns of carboniferous era, 167. 
 Fishes of the old red sandstone, 137. 
 Fire-clays, their value and applications, 
 
 183. 
 Flint implements of Abbeville, &c , 
 
 284. 
 
 Flora of the carboniferous era, 167. 
 Fluviatile accumulations of current 
 
 era, 251. 
 Fluvio-marine formations of current 
 
 era, 255. 
 Footprints, fossil, of triassic system, 
 
 195. 
 Footprints, fossil, of old red sandstone, 
 
 136. 
 
 Foraminifera, their nature and opera- 
 tions, 44. 
 Foraminiferal deposits of current era, 
 
 259, 266. 
 Forbes, Principal, on glacier motion, 
 
 221. 
 Forests, submarine, of British coasts, 
 
 247. 
 
 Formation, definition of, in geology, 23. 
 Fossil, definition of the term, 111. 
 Fossil remains, how imbedded, 113. 
 Fossils, modes in which they occur 
 
 (note), 127. 
 
 FOSSILS, THEIR NATURE AND ARRANGE- 
 MENT, 111-128. 
 
 Fossils, the medals of creation, 115. 
 
INDEX. 
 
 325 
 
 Freezing, the principle of, 225. 
 
 Freezing, effects of, on rocks and soils, 
 217. 
 
 Fremy, M., on the chemical composi- 
 tion of coal, 153. 
 
 Frost, geological effects of, 39. 
 
 Frosts, from night radiation, 225. 
 
 Future, its character and arrangements, 
 309-322. 
 
 Future of the earth, man's influence 
 on, 320. 
 
 Geology, economic importance of the 
 study, 32. 
 
 Geology, relation of, to physical geo- 
 graphy, 27. 
 
 Geology, scientific advantages .of the 
 study, 32. 
 
 Glacial epoch, its different stages, 247. 
 
 Glacial epoch, its geographical limits, 
 
 Glacial epoch, theories and hypotheses, 
 243. 
 
 Glacial groovings and striations, 235. 
 
 GLACIAL OR ICE-EPOCH, THE, 231-248. 
 
 Glacier motion, description of, by 
 Forbes, 221. 
 
 Glaciers, formation and effects of, 219. 
 
 Glyptodon, tertiary mammal, 207. 
 
 Gold-drifts in creeks and gullies, 252. 
 
 Granitic rocks, summary of, 62. 
 
 Graptolites of the Silurian system, 95. 
 
 Ground-ice, nature and effects of, 226. 
 
 Guano deposits, their age and magni- 
 tude, 265. 
 
 Hail, nature and formation of, 215. 
 Haughton, Professor, quoted, 208. 
 Heat, metamorphic effects of, 73. 
 Heer, Professor, on current flora of 
 
 Europe, 271. 
 Historic and pre-historic formations, 
 
 269. 
 
 Hoar-frost, production of, 215. 
 Holoptychius, fish of old red sand- 
 stone, 138. 
 
 - Hot springs in connection with volcan- 
 oes, 55. 
 
 Hull's ' Coal-fields of GreatBritain,' 174. 
 Human and pre-human formations, 269. 
 Human remains and implements in 
 
 Europe, 278. 
 Humboldt, on relative ages of rocks, 
 
 24. 
 Button, Dr, on our knowledge of the 
 
 future, 309. 
 
 Hutton, Dr, quoted, 35. 
 Hysenodon, tertiary carnivore, 210. 
 Hypozoic rocks, definition of, 99. 
 
 Ice, preservative effects of, 229. 
 
 Icebergs, their formation and magni- 
 tude, 222. 
 
 Ice-caverns,Mr Browne's account of ,223. 
 
 Ichthyosaurus, secondary reptile, 195. 
 
 Igneous agencies, geological results of, 
 45. 
 
 Igneous phenomena of carboniferous 
 era, 165. 
 
 Igneous rocks, volcanic, trappean, and 
 granitic, 62. 
 
 Industrial importance of geology, 32. 
 
 Infusorial or microphytal earths, 211. 
 
 Inorganic and organic, difference be- 
 tween, 295. 
 
 Xj Interior of the globe, supposed nature 
 of, 18. 
 
 Intermediate forms of the tertiary epoch, 
 208. 
 
 Iron, bronze, and stone ages, relative 
 antiquities, 279. 
 
 Iron, its applications and importance, 
 ISO. 
 
 Ironstones of the coal formation, 180. 
 
 Ice, formation and nature of, 214. 
 Ice, general functions of, 229. 
 Ice in the atmosphere, 215. 
 
 ICE, ITS FORMS AND FUNCTIONS, 213-230. 
 
 Ice on land, 216. 
 Ice on water, 225. 
 
 Jukes, Professor, quoted, 209. 
 Kjokken-modding of Denmark, &c., 283 
 
 Labyrinthodon, character of, 195. 
 Lacustrine formations of current era, 
 253. 
 
 Lake-dwellings of Europe, 254. 
 
 Lake-dwellings of Europe, apparent age 
 of, 282. 
 
 Land and water of the future, 311. 
 
 Landes de Bourdeaux, origin of, 260. 
 
 Laurentian system, its rocks and fos- 
 sils, 87. 
 
 Lava-cones, general slope of, 52. 
 
 Lava discharges, magnitude of, 268. 
 
 Law of progression, incessant operation 
 of, 319, 321. 
 
 Levels of England, their formation, 256. 
 
 Life, as a branch of natural science, 306. 
 
 Life, first traces of, 97. 
 
 Life, future distributions of, 314. 
 
 Life, its forms and functions, 297. 
 
 Life, its grades and arrangements, 298. 
 
 Life, its origin and first appearance, 294. 
 
 Life, its progressive ascent in time, 300. 
 
 Life, its relations and physical condi- 
 tions, 296. 
 
 Lignites of Austria, their value, 148. 
 
 Lignites or brown coals, nature of, 147. 
 ~-^4 Limestone, its applications and import- 
 ance, 181. 
 
 Limestones of the carboniferous sys- 
 tem, 161. 
 
 Links or sand-drifts of British shores, 
 259 
 
 Littoral concrete, nature and origin of 
 71. 
 
 Lyell on tertiary formations, 203. 
 
 Lyell's, Sir Charles, description of 
 Richmond coal, 149. 
 
326 
 
 INDEX. 
 
 Magnetic currents, metamorphic effects 
 of, 74. 
 
 Mammals, age of, 207. 
 
 Mammals, marsupial, of the oolite, 196. 
 
 Mammoth, extinction of, in Europe, 270. 
 
 Mammoth remains, how preserved iu 
 Siberia, 230. 
 
 Mammothian stage of post-tertiary sys- 
 tem, 286. 
 
 Man, high relative antiquity of, 285. 
 
 Man, his varieties and their relative 
 antiquity, 28S. 
 
 Man's influence on the future, 320. 
 
 Man's origin a question of natural his- 
 tory, 289. 
 
 Man's place, as a geological problem, 
 277. 
 
 MAN'S PLACE IN THE GEOLOGICAL RE- 
 CORD, 273-292. 
 
 Man's remains in Western Europe, 278. 
 Mantell's 'Medals of Creation' quoted, 
 
 115. 
 
 Marine formations of current era, 258. 
 Marsupial mammals of the oolite, 196. 
 Megatherium, tertiary mammal, 207. 
 Mesozoic formations, definition of, 26, 
 
 29. 
 
 * Metamorphic rocks, their arrange- 
 ments, 77. 
 Metamorphic rocks, the so-called, 76, 
 
 77. 
 <Metamorphism, all-pervading influence 
 
 of, 80. 
 '. METAMORPHISM OR TRANSFORMATIONS 
 
 OF ROCK-MATTER, 69-82. 
 Metamorphisin, summary of causes, 75. 
 Meteoric agencies, their operations, 38. 
 Microscopic organisms, accumulations 
 
 of, 44. 
 Miller's, Hugh, 'Old Red Sandstone,' 
 
 129. 
 
 Millstone grit formation, nature of, 161. 
 Mineral and metalliferous districts, as- 
 pects of, 108. 
 
 Miocene tertiaries, definition of, 203. 
 Mixed rocks, character of, 24. 
 Moraines, terminal, medial, and lateral,- 
 
 220. 
 Mountain or carboniferous limestone, 
 
 161. 
 Musk-ox, date of, in Europe, 281. 
 
 Neolithic or younger stone age, 280. 
 V Neve, nature and formation of, 216. 
 Northern drift or glacial drift, 238. 
 
 -'Gaze or ooze of Atlantic sea-bed, 259. 
 Ocean-currents, geological effects of, 
 
 Oil-shales of coal formation, 173, 183. 
 OLD COAL-MEASURES, THE, 159-176. 
 
 OLD RED SANDSTONE, THE, 129-142. 
 
 Old red sandstone, its fossils, 134. 
 Old red sandstone, its rocks, 131. 
 Old red sandstone, probable climate of 
 period, 133. 
 
 Oolitic coal of Richmond in Virginia, 
 149. 
 
 Oolitic or Jurassic system, 189. 
 
 ORDER AND SUCCESSION OF LIFE, 293-308. 
 
 Organic agencies, geological effects of, 
 43. 
 
 Organic and inorganic, difference be- 
 tween, 295. 
 
 Organic formations of current era, 263. 
 
 Organic structures most readily pre- 
 served, 116. 
 
 Ornithiclmites or bird footprints, 195. 
 
 Owen, progression of human species 
 307. 
 
 Owen's description of the archseopteryx, 
 
 Palaeolithic or ancient stone age, 280. 
 Palaeontology, the science of fossils, 1 12. 
 Palseophytology, science of fossil plants, 
 
 Palseotherium, tertiary mammal, 207. 
 Palaeozoic formations, definition of 26 
 
 29. 
 Palseozoology, science of fossil animals, 
 
 112. 
 Parka decipiens, fossil crustacean 
 
 spawn (?), 136. 
 Peat-moss, growth of, 43. 
 Peat-moss, nature and formation of. 
 
 146. 
 
 Peat-mosses of temperate latitudes, 263. 
 Pelagic or deep-sea deposits, 259. 
 Petrifaction, nature of the process, 118. 
 Petrifaction, preservative effects of 
 
 119. 
 
 Pfahlbauten or pile-dwellings of Swit- 
 zerland, 254. 
 Physical geography, relations of, to 
 
 geology, 27. 
 
 Pile-dwellings in lakes, 254. 
 Plant-growths, geological results of, 43. 
 Plants and animals of the future, 316. 
 Plants, systematic classifications of, 
 
 121, 122. 
 
 Polar seas, formation of ice on, 226. 
 Polders of Holland, 258. 
 Post-tertiary formations, arrangement 
 
 of, 250. 
 Pre-historic and historic formations, 
 
 269. 
 
 Pre-historic remains of man, 281. 
 Pressure, metamorphic effects of, 70. 
 PRIMARY PERIODS, THE, 83-100. 
 Progression, law of, its irresistible pro- 
 gress, 321. 
 
 Progression of life in the future, 318. 
 Progressive ascent of plants and ani- 
 mals, 300. 
 Pteraspis, fish of old red sandstone, 
 
 138. 
 
 Pterygotus, crustacean of the old red, 
 13t>. 
 
 Quaternary or post tertiary formations 
 249. 
 
INDEX. 
 
 327 
 
 Rain, geological effects of, 39. 
 
 Raised beaches, examples of, 59. 
 
 Raised beaches or ancient sea-margins, 
 260. 
 
 RECENT FORMATIONS, 249-272. 
 
 Rein-deer stage of post-tertiary era, 286. 
 
 Reptiles occurring in carboniferous 
 system, 169. 
 
 Reptiles, so called, age of, 193. 
 
 Rhinoceros, woolly-haired, extinction 
 of, 270. 
 
 Rhytina, extinction of, in Behring 
 Island, 271. 
 
 River-gravels, high and low level, 257. 
 
 Rivers, geological effects of, 41. 
 
 Roches moutonne'es, how formed, 221. 
 
 Rock, definition of the term, 19. 
 
 Rock - formations, chronological ar- 
 rangement of, 29. 
 
 Rocks, chemical composition, 24. 
 
 Ross, Sir James, on antarctic icebergs, 
 222. 
 
 Salinas of South America, their pro- 
 ducts, 261. 
 
 Salses, definition of, 55. 
 Salt-water ice, nature and formation 
 
 of, 226. 
 
 Sand-dunes or drifts of existing sea- 
 shores, 259. 
 Sandstones of the coal-measures, their 
 
 value, 182. 
 
 Scandinavian coast, uprise of, 58, 59. 
 Scientific importance of geological 
 
 science, 32. 
 Sea-ice, varieties and descriptions of, 
 
 227. 
 Sea-margins or ancient sea -beaches, 
 
 880. 
 
 SECONDARY AGES, THE, 186-200. 
 Secondary formations, economic value 
 
 of, 199. 
 Secondary systems, nature of their 
 
 strata, 191. 
 Secondary systems, their fossil flora 
 
 and fauna, 192. 
 Secondary systems, their systematic 
 
 arrangement, 190. 
 
 Seismology, science of earth-shocks, 66. 
 Serpula reefs, their formation and 
 
 thickness, 265. 
 Slnlcs and coals, distinction between 
 
 (note), 154. 
 
 Shales of the coal-measures, 163. 
 Shales of the coal-measures, their 
 
 value, 183. 
 Shell-beds, their formation and extent, 
 
 265. 
 
 Siberian coast, uprise of, 58, 59. 
 Silurian system, its rocks and fossils, 
 
 93. 
 
 Sinters, calcareous and siliceous, 262. 
 Sivatherium, tertiary mammal, 210. 
 Snow, nature and formation of, 215. 
 Snow-line, latitudinal limits of, 218. 
 Soil, fossil, of the oolite (note), 197. 
 
 fiolfataras and suffioni, 55. 
 
 Solitaire, extinction of, in Mauritius, 
 271. 
 
 Sombrero, island, and formation of, 265. 
 
 Spawn (fossil) of crustaceans, 136. 
 
 Springs, geological results of, 42. 
 
 Stalactites and stalagmites, their ori- 
 gin, 262. 
 
 Stalagmites and stalactites, their ori- 
 gin, 262. 
 
 Stone age, subdivisions of, 280. 
 
 Stone, bronze, and iron ages, relative 
 antiquities, 279. 
 
 Stone implements found in India, 289. 
 
 Stratheden in Fife, its formations, 257. 
 1 Stratified rocks, how formed, 20. 
 
 Stream-works, nature of, 109. 
 
 Stylonurus, crustacean of the old red, 
 136. 
 
 Sub-fossil, definition of the term, 111. 
 
 Submarine forests of Britain (note), 
 258. 
 
 Submarine forests of British coasts, 
 267. 
 
 Sun-cracks on strata of old red sand- 
 stone, 133. 
 
 Surveys, geological, progress of, 199. 
 
 Swamp and jungle growths, 264. 
 
 Tait, Bishop, on the duty of scientific 
 
 inquiry, 277. 
 
 Temperature of the earth's interior, 18. 
 Terraces, on river banks, 251. 
 Tertiary basins of Europe, 204. 
 Tertiary flora and fauna, 205, 207. 
 Tertiary strata, their economic value 
 
 211. 
 
 Tertiary system, subdivisions of, 203. 
 TERTIARY TIMES, 201-212. 
 Theophrastus on coal, 157. 
 Theories of life development, 302. 
 Theory of the earth, Button's, quoted, 
 
 20, 35, 49, 57. 
 
 Tides, their geological effects, 41. 
 Transition rocks of the older geologists, 
 
 77. 
 
 Trap rocks, summary of, 62. 
 Travertines or calcareous tufas, 262. 
 Trias or triassic system, 189. 
 Trilobites of the Silurian system, 95. 
 Tripoli or polishing stone, nature of, 
 
 Tropical character of future lands, 
 
 312: 
 Tufa-cones, nature and inclination of, 
 
 52. 
 Tufas, calcareous and siliceous, 262. 
 
 Unstratified rocks, how formed, 21. 
 Uralla gold-field, section of, 253. 
 
 Variation, tendency to, in plants and 
 
 animals, 317. 
 Vegetable kingdom, schemes of, 121, 
 
 122. 
 Wein and vein-stuffs, definition of, 103. 
 
328 
 
 INDEX. 
 
 Veins, general composition of, 104. 
 Veins, their formation and infiltration, 
 106. 
 
 VEINS, THEIR NATURE AND ORIGIN, 
 101-110. 
 
 Vital development, theories of, 302. 
 
 Vital development, treatment of the- 
 ories, 305. 
 
 Volcanic accumulations of current 
 epoch, 267. 
 
 Volcanic areas of present day, 62, 64. 
 
 Volcanic cones, various slopes of, 53. 
 
 Volcanic products, summary of, 62. 
 
 Volcanoes, nature and operations of, 52. 
 
 Volcanoes, upheaval and accumulation 
 theories, 54. 
 
 Vulcanism, cosmical functions of, 63. 
 
 VULCANISM, ITS NATURE AND FUNC- 
 TION, 51-68. 
 
 Vulcanism, mechanical and chemical 
 theories of, 60. 
 
 Vulcanism, necessary portion of world 
 
 mechanism, 63. 
 Vulcanism, vulcanicity, Humboldt's 
 
 definition of, 61. 
 
 "Wash-outs," probable nature of, 166. 
 WASTE AND REPRODUCTION, 35-50. 
 Water, its nature and circulation, 213. 
 Waves, geological effects of, 41. 
 Wealden formation, nature of, 189. 
 Wenham ice, how prepared, 225. 
 WHAT OF THE FUTURE? 309-322. 
 WHAT WE OWE TO OUR COAL-FIELDS, 
 
 177-186. 
 
 Winds, geological effects of, 39. 
 Worm-trails and burrows of the old red, 
 
 132. 
 
 Zamias of secondary system, 197. 
 
 THE END. 
 
 PRINTED BY WILLIAM BLACKWOOD AND SONS, EDINBURGH. 
 
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