UNIVERSITY OF CALIFORNIA AT LOS ANGELES IN MEMORIAM BERNARD MOSES The RALPH D. REED LIBRARY o DEPARTMENT OF GEOLOGY UNIVERSITY OF CALIFORNIA LOS ANGELES, CALIF. SKETCH BOOK OF POPULAR GEOLOGY. POPULAR GEOLOGY: SERIES OF LECTURES READ BEFORE THE PHILOSOPHICAL INSTITUTION OF EDINBURGH. litters from a 6toI0pt's f 0rif0Ii0. i BY HUGH MILLER. INTRODUCTORY RESUME OF THE PROGRESS OF GEOLOGICAL SCIENCE WITHIN THE LAST TWO YEARS, B Y MBS. MILLER. BOSTON: GOULD AND LINCOLN, 58 WASHINGTON STREET. NEW YORK: SHELDON AND COMPANY. CINCINNATI: GEORGE 8. BLANCHARD. 1860. Entered according to Act of Congress, in the year 1859, by < , < > I L D AND LINCOLN, lu the Clcik'H OfTico of the District Court of the District of Massachusetts I \1-IH IIV W. K. l>r.,M>i;il, AMX>Vtlt, MASS. .(CI. \TKIi 11Y OLO. C. UAKU It AVEItY, BO8TXIN. Geolog Lib Jo PREFACE TO THE AMERICAN EDITION THIS new volume, from the pen of HUGH MILLER, is a legacy wholly unlocked for by the American public. It was known to many of his admirers on this side of the Atlantic that he had been labor- ing for years on a work designed to be the magnum opus of his life "THE GEOLOGY OF SCOTLAND." But his untimely death, it was supposed, had cut short his labors, and left the work in a state so . fragmentary that his literary executors would not venture to publish it. The impression was a correct one, as related to the design of the author, in its magnitude and completeness. But the present volume supplies, to general readers, what the proposed work would have done for the scientific world. It gives the geological history of Scotland and, with Scotland, of the world in language intel- ligible to all, and with an affluence of anecdote, and incident, and literary allusion, in which HUGH MILLER was without an equal among the scientific writers of our century. It gives precisely what II PREFACE. a multitude of readers in this country have been longing to find a rational account of the manner in which all the strata of the earth's crust have been formed, from the foundation of unstratified granite and gneiss to the alluvial deposits of its surface. Scotland is literally taken to pieces, like a house of many stories; and one looks on the processes of the Divine Architect, as he would on the work of a human builder. The hypotheses (for they can be regarded only as such) are original, and curious, and plausible. Some read- ers may doubt their accuracy, but none will question the eminent ability with which they are developed. The volume will add to the reputation of the author, and the popularity of his writings; and wfll aid many, who have a slight acquaintance with geological science, to form habits of practical observation in their country rambles. The American Publishers have given the title of "Descriptive .Sketches" to sundry papers which Mrs. Miller has selected from unpublished manuscripts of her husband, and to which, with charac- teristic modesty, she gave the simple name of "Appendix." They regarded these papers as an important part of the volume, and de- manding, from their intrinsic merits, a distinctive title. BOSTON, APRIL, 1859. THE REV. . S. SYMONDS, RECTOR OF PENDOCK, HEREFORDSHIRE. DEAR SIR, Am I presuming too much on my position, as merely the editor of the following Lectures, when I ask leave to dedicate them to you? It ia unquestionably a liberty with the production of another which only very pecu- liar circumstances can at all excuse. Yet, in the present case, I venture to think that those peculiar circumstances do exist ; and I feel assured he would readily pardon me, whose work this is, and whose memory you so much revere. Without your cooperation, I believe that neither the " Cruise of the Betsey" nor these pages could by this tune have seen the light. When my own over- laden brain refused to do its duty, you gave me to hope, by offers of well- timed assistance, that the task before me might still be accomplished. Your friendly voice, often heard in tones of sympathizing inquiry when I was una- ble to endure your own or any other human presence, even that of my dear child, was for a time the only sound that brought to my heart any promise or cheer for the future. It was then, while unable to read the very characters in which they were written, that I put into your hands the papers containing "The Cruise" and "Ten Thousand Miles over the Fossiliferous Deposits of Scotland." You undertook the editorial duties connected with them con amore, and performed your task in a manner that left nothing to be desired. During the preparation of the present volume for the press, you have given me all the advantage of your ready stores of information, both in carefully Ecrutinizing the text to see where any addition was required in the form of IV DEDICATION. notes, and in referring me to the best authorities on every point regarding which I consulted you. And while so doing, you have confirmed my own judgment, perhaps too liable to be swayed by partiality, by expressing your conviction that this work is calculated to advance the reputation of its author. Long may you be spared to be, as now, the life and soul of those scientific pursuits so successfully carried on in your own district! Many a happy field- day may you enjoy in connection with that Society of which yon are the hon- ored president Would that all associations throughout our country were as harmless in their methods of finding recreation, as invigorating to body and mind, and as beneficial in their results to the cause of science! In exploring the beautiful fields, and woods, and eunny slopes of Worcestershire, and Here- fordshire, in earnest and healthful communings with nature, and, I trust, with nature's God, the perennial springs of whose bounty are seldom quaffed in this manner as they ought to be, I trust that much, much happiness is in store for you and for the other gentlemen of the Malvern Club,* to whom, as well as to yourself, I owe a debt of grateful remembrance. And for the higher and nobler work which God has given you to do, may he grant you no stinted measure of bis abundant grace, to enable you to per- form it aright. Ever believe me, dear Sir, Yours most faithfully, LYDIA MILLER. Tha Malrern Club devote* itatcd period*, monthly, I think, to ramble* over twenty or thirty mile* of country, when the naturtliitt of whom it ii composed, botanitta, geologist*, etc., eny on the re*erche of their variou* department* separately, or In little group) of two or three, a* they my deilre. They til dine afterward* together at MI inn, or torn-home, the ew may be, where they relate the adTenture* of the day, diicnii thtir favorite topici, and com- pare their newly-found (nature*. At a eontequence of thit. the Malrern Muteum it a perfect model of what a local mnteum ought to be. There I* no town or district of country where (w younj men. pmtefini the advantage of an oecaiional holiday, might not thut awociaU I with the >tmo*t a.lvantacc both to themtelTet and other*. CONTENTS. INTRODUCTORY RESUME OF THE PROGRESS OF GEOLOGICAL SCI- ENCE, 11 LECTURE FIRST. Junction of Geologic and Human History Scottish History of Modern Date The two periods previous to the Roman Invasion; the Stone Age and the Bronze Age Geological Deposits of these Pre-historic Periods The Aborig- inal Woods of Scotland Scotch Mosses consequences of the Roman Invasion How Formed Deposits, Natural and Artificial, found under them The Sand Dunes of Scotland Human Remains and Works of Art found in them An Old Church Disinterred in 1835 on the Coast of Cornwall Controversy regarding it Ancient Scotch Barony underlying the Sand The Old and New Coast Lines in Scotland Where chiefly to be observed Geology the Science of Landscape, Scenery of the Old and New Coast Lines Date of the Change of Level from the Old to the New Coast Line uncertain Beyond the Historic, but within the Human Period Evidences of the fact in remains of Primitive Weapons and Ancient Boats Changes of Level not rare events to the Geologist Some of these enumerated The Boulder-Clay Its preva- lence in the Lowlands of Scotland Indicated in the Scenery of the Country The Scratchings on the Boulders accounted for Produced by the Grating of Icebergs when Scotland was submerged Direction in which Icebergs floated, from West to East " Crag and Tail," theeflect of it Probable Cause of the Westerly Direction of the Current, 37-88 1* VI CONTENTS. LECTURE SECOND. Problem first propounded to the Author in a Quarry The Quarry's Two De- posits, Old lied Sandstone and Boulder-Clay The Boulder-Clay formed while the Laud was subsiding The Groovings and 1'olishiugs of the Recks in the Lower Parts of the Country Evidences of the fact Sir Charles Lyell's Ob- servations on the Canadian Lake District Close of the Boulder-Clay Record in Scotland I t Continuance in England into the Pliocene Ages The Trees and Animals of the Pre-Glacial Periods Elephants' Tusks found in Scotland and England regarded as the Remains of Giants Legends concerning them Marine Deposits beneath the Pre-Glacial Forest* of England Objections of Theologians to the Geological Theory of the Antiquity of the Earth ond of the Human Race considered Extent of the Glacial Period in Scotland Evi- dences of Glacial Action in Glencoe, Garelock, and the Highlands of Suther- landScenery of Scotland owes its Characteristics to Glacial Action The Prriod of Elevation which succeeded the Period of Subsidence Its Indica- tions in Raised Beaches and Subsoils How the Subsoils and Brick Clays were formed Their Economic Importance Boulder-Stones interesting fea- tures in the Landscape Their prevalence in Scotland The more remarka- ble Ice-travelled Boulders described Anecdotes of the "Travelled Stone of Petty "and the Standing-Stone of Torribal Elevation of the Land during tb Post-Tertiary Period which succeeded the Period of the Boulder-Clay The Alpine Plants of Scotland the Vegetable Aborigines of the Country Panoramic View of the Pleistocene and Post-Tertiary Periods Modern Sci- ence not adverse to the Development of the Imaginative Faculty, . 84-124 LECTURE THIRD. The Pot Delta (Dr. Moir) His Definition of Poetry Hia Death His Burial Place at Invereak Vision, Geological and Historical, of the surrounding Country What it te that imparts to Nature its Poetry The Tertiary Forma- tion in Scotland In Geologic History all Ages contemporary Amber the n of the Pi*u* Sureini/rr A Vegetable Production of the Middle Tertiary CONTENTS. VII Ages Its Properties and Uses The Masses of Insects inclosed in it The Structural Geology of Scotland Its Trap Rock The Scenery usually asso- ciated with the Trap Rock How Formed The Cretaceous Period in Scot- landIts Productions The Chalk Deposits Death of Species dependent on Laws different from those which determine the Death of Individuals The Two Great Infinites, 125-167 LECTURE FOURTH. The Continuity of Existences twice broken in Geological History The Three Great Geological Divisions representative of three Independent orders of Ex- istences Origin of the Wealden in England Its great Depth and high An- tiquity The question whether the Weald Formation belongs to the Creta- ceous or the Oolite System determined in favor of the latter by its Position in Scotland Its Organisms, consisting of both Salt and Fresh Water Animals, indicative of its Fluviatile Origin, but in proximity to the Ocean The Out- liers of the Weald in Morayshire Their Organisms The Sabbath- Stone of the Northumberland Coal-Pita Origin of its Name The Framework of Scotland The Conditions under which it may have been formed The Lias and the Oolite produced by the last great Upheaval of its Northern Mountains The Line of Elevation of the Lowland Counties Localities of the Oolitic Deposits of Scotland Its Flora and Fauna History of one of its Pine Trees Its Animal Organisms A Walk into the Wilds of the Oolite Hills of Sutherland, . ' 16&-202 LECTURE FIFTH. The Lias of the Hill of Eathie The Beauty of its shores Its Deposits, how formed Their Animal Organisms indicative of successive Platforms of Exis- tences The Laws of Generation and of Death The Triassic System Its Economic and Geographic Importance Animal Footprints, but no Fossil Organisms, found in it The Science of Ichnology originated in this fact Illustrated by the appearance of the Compensation Pond, near Edinburgh, VIII CONTENTS. in 1842 The Phenomena indicated by the Foot-print* in the Triassic System The Triassic and Permian Systems once regarded as one, under the name of the New Red Sandstone The Coal Measures in Scotland next in Order of Succession to the Triassic System Differences in the Organisms of the two Systems Extent of the Coal Measures of Scotland Their Scenic Peculiari- tiesAncient Flora of the Carboniferous Period Its Fauna Its Reptiles and Reptile Fishes The other Organisms of the Period Great Depth of the System The Processes by which, during countless Ages, it had been formed 203-248 LECTURE SIXTH. Remote Antiquity of the Old Red Sandstone Suggestive of the vast Tracts of Time with which the Geologist has to deal Its great Depth and Extent in Scotland and England Peculiarity of its Scenery Reflection on first dis- covering the Outline of a Fragment of the Asterolepis traced on one of its Rocks Consists of Three Distinct Formations Their Vegetable Organisms The Caithness Flagstones, how formed The Fauna of the Old Red Sand- stone The Pterichthys of the Upper or Newest Formation The Cephalaspis of the Lower Formation The Middle Formation the most abundant in Or- ganic Remains Destruction of Animal Life in the Formation sudden and violent The Asterolepis and Coccostens The Silurian the Oldest of the Geologic Systems That in which Animal and Vegetable Life had their earliest beginnings - The Theologians and Geologists on the Antiquity of the Globe Extent of the Silurian System in Scotland The Classic Scenery of the country situated on it Comparatively Poor in Animal and Vegetable Organisms The Unfossiliferous Primary Rocks of Scotland Its Highland Scenery formed of them Description of Glencoe Other Highland Scenery glanced at Probable Depth of the Primary Stratified Rocks of Scotland How deposited Speculations of Philosophers regarding the Processes to which the Earth owe* its present Form The Author's views on the subject, 249-298 CONTENTS OF DESCRIPTIVE SKETCHES. Page ACCUMULATIONS OF SHELLS, PHENOMENA EXPLANATORY band, consider a succession and development of type to be the one great fixed law of geological science. The reader will see that in the end of Lecture Third such remains as have been found lower than the Tertiary are expressly recognized and excepted. " Save," says the author, " in the dwarf and inferior forms of the marsupials and insectivora, not any of the honest mammals have yet appeared." But while attaching no importance to the discoveries in the Middle Purbeck, except in regard of more ample numerical development, it is necessary to admit the evidence of marsu- pials having been found lower than the Stonesfield or Great Oolite; even so far back as the Upper Trias, the Keuper Sandstone of Germany, which lies at the base*of the Lias. I must be permitted, on this point, to quote the authority of Sir Roderick Murchison, as one of the safest and most cautious exponents of geological fact. " In that deposit," says he, referring to the Keuper Sandstone of Wurtemberg, " the relics of a solitary small marsupial mammal have been ex- humed, which its discoverer, Plieninger, has named Mtcrolestcs Antiquus. Again, Dr. Ebenezer Emmons, the well-known geologist, of Albany, in the United States, has described, from the lower beds of the Chatham Secondary Coal-field, North 1 >!ina (of the same age as those of Virginia, and probably of the Wurtemberg Keuper), the jaws of another minute mam- mal, which he calls Dromotherium Sylvestre. Lastly, while I PROGRESS OF GEOLOGICAL SCIENCE. 19 write, Mr. C. Moore has detected in an agglomerate which fills the fissures of the carboniferous limestone near Frome, Somersetshire, the teeth of marsupial mammals, one of which he considers to be closely related to the Microkstes Antiquus of Germany, and Professor Owen confirms the fact. From that coincidence, and also from the association with other ani- mal remains, the Placodus (a reptile of the Muschelkalk), and certain mollusca, Mr Moore believes that these patches represent the Keuper of Germany. If this view should be sustained, this author, who has already made remarkable additions to our acquaintance with the organic remains of the Oolitic rocks and the Lias, will have had the merit of having discovered the first traces of mammalia in any British stratum below the Stonesfield slates." . . . . " Let me entreat," says Sir Roderick, in a passage occurring shortly after that we have quoted, " Let me entreat the reader not to be led by the reasoning of the ablest physiologist, or by an appeal to minute structural affinities, to impugn the clear and exact facts of a succession from lower to higher grades of life in each forma- tion. Let no one imagine that because the bony characters in the jaw and teeth of the Plagiaulax of the Purbeck strata are such as the comparative anatomist might have expected to find among existing marsupials, and that the animal is, therefore, far removed from the embryonic archetype, such an argument disturbs the order of succession of classes, as seen in the crust of the earth." So far from disturbing the order of succession, 20 INTRODUCTORY RESUME: it is, we conceive, of exceeding interest to find the Mesozoic period marked in its commencement, as it most probably will be found to be, by the introduction of a form of being so entirely different from any that preceded it It seems to us to bring the true development hypothesis into a clearer and more harmonious unity. The great period during which the little annelide or sand-boring worm was the sole tenant of this wide earth, its first inhabitant after the primeval void, has passed. The aeon of the Mollusc and the Crustacean follows. At its close appear the first fishes, very scanty in point of numbers and of species, but multiplying into many genera, and swarming in countless myriads, as the Devonian ages wear on. Again, towards the termination of the latter, appear the first reptiles, which, during the Carboniferous and Permian eras, reign as the master-existences of creation. But Palaeozic or ancient life passes away, and the Mesozoic or Middle period is marked not only by countless forms, all specifically, and many of them generically, new, but by another wholly un- known, either as genus or species, during all the past. The little marsupials and insectivora appear "perfect after their kind," and yet only the harbingers of the great mammalian period which is yet to come. In the volume of Creation, as in that of Providence, God's designs are wrapt in profound niy-tory until their completion. And yet in each it would appear that He sends a prophetic messenger to prepare the PROGRESS OF GEOLOGICAL SCIENCE. 21 way, in which the clear-sighted eye, intent to read His pur poses, may discern some sign of the approaching future. Before we proceed, we must here, on behalf of the un- learned, and therefore the more easily misled, most humbly venture to reclaim against the use, on the part of men of the very highest standing, of the loose and dubious phraseology in which they sometimes indulge, and which serves greatly to perplex, if not to lead to very erroneous conclusions. "In respect to no one class of animals," says Professor Owen, in his last Address to the British Association, "has the manifestation of creative force been limited to one epoch of tune." This, translated into fact, can only mean that the vertebrate type had its representative in the fish of the earliest or Silurian epoch, and has continued to exist throughout all the epochs which succeeded it. But the difficulty lies in the translation ; for, at first sight, the conclusion is inevitable, to the general reader, that not only the lowest class of vertebrate existence, but also man and the higher mammals, had been found from the beginning, and that the highest and the lowest forms of being were at all periods contemporary. No one, surely, would have a right to make such a prodigious stride in the line of inference, on the presumption of supposed evidence yet to come. Again, Sir Charles Lyell, in his supplement to the fifth edition of his " Elementary Geology," says, in speak- 22 INTRODUCTORY RESUME: ing of these same Purbeck beds quarried by Mr. Beckle?. " They afford the first positive proof, as yet obtained, of the coexistence of a varied fauna of the highest class of vertebrata with that ample development of reptile life which marks the periods from the Trias to the Lower Cretaceous inclusive." Are marsupials and insectivora the highest class of vertebrata ? Where, then, do the great placental mammals where does man himself take rank ? It were surely to be desired that some stricter and more invariable form of phraseology were adopted, either in accord- ance with the divisions of Cuvier, or some analogous system, adherence to which would be clearly defined and understood. Why should not the words class, order, type, have as invariable a meaning as genera and species, which, having an application more limited, are seldom mistaken ? We are aware that such terms are often used by the learned in an indefinite and trans- latable sense, just as to the learned in languages it may be a matter of indifference whether the written characters which convey information to them be Roman, Hebrew, or Chinese. But it should be remembered that there is a large class outside which seeks to be addressed in a plain vernacular which asks, first of all, definiteness in the use of terms to which prob- ably they have already sought to attach some fixed sense ; and that it is not well to unship the rudder of their thought, and send them back to sea again. PROGRESS OF GEOLOGICAL SCIENCE. 23 The next point which demands attention in our short resume is that great break between the Permian and Triassic systems, across which, as stated in the following pages, not a single species has found its way. Much attention has been given to the great Hallstad or St. Cassian beds, which lie on the north- ern and southern declivities of the Austrian Alps. These beds belong to the Upper Trias, and they contain more genera com- mon to Palaeozoic and newer rocks than were formerly known. There are ten genera peculiarly Triassic, ten common to older, and ten to newer strata. Among these, the most remarkable is the Orthoceras, which was before held to be altogether Palaeozoic, but is here found associated with the Ammonites and Belemnites of the secondary period. 1 The appearance of this, with a few other familiar forms, serves, in our imagina- tion at least, to lessen the distance, and, in some small measure, to bridge over the chasm, between Palaeozoic and Secondary life. And yet, considering the vast change which then passed over our planet, that all specific forms died out, while new ones came to occupy fcheir room, the discovery of a few more connecting generic links in the rudimentary shell-alphabet, which serve but to show that in all changes the God of the past is likewise the God of the present, no more affects in reality this one great revolution, the completeness of which is marked by the very difficulty of finding, amid so much new 1 See Sir Charles Lyell's " Supplement " for corroboration of the forego- ing statements. 24 INTRODUCTORY RESUME: and redundant life, a single identical specific variety, than the well-known existence of the Terebratula in the earliest, as well as in the existing seas, can efface the great ground-plan of successive geological eras. 1 Nor does it explain the matter to say that geographical changes took place, bringing with them the denizens of different climates, and adapted for different modes of life. The same Almighty Power which now pro- vides habitats and conditions suitable for the wants of his creatures, would, doubtless, have done so during all the past. Geographical changes are at all times indissolubly connected with changes in the conditions of being ; and they serve, in so far, to explain the rule in the stated order of geological events, when a due proportion of extinct and of novel forms are found coexistent. But how can they explain the exception ? A singular effect must have a singular cause. And when we find that there were changes relating to the world's inhabitants altogether singular and abnormal in their revolutionary char- acter, we must infer that the medial causes of which the Crea- tor made use were of a singular and abnormal character also. On this head the best-informed ought to speak with extreme diffidence. We can but imagine that there may have been a long, immeasurable period, during which a subsidence, so to speak, took place in the creative energy, and during which all specific forms, one after another, died out, the lull of a dying l See Terebratula, page 111. The extinct Terebratnla is now called Rhrnronclla. PROGRESS OF GEOLOGICAL SCIENCE. 25 creation, and then a renewal of the impulsive force from that Divine Spirit which brooded over the face of the earliest chaotic deep, producing geographical changes, more or less rapid, which should prepare the way for the next stage in our planetary existence, its new framework, and its fresh burden of vital beings. The other great break in the continuity of fossils, which occurs between the Chalk and the Tertiary, seems to be very much in the same condition with that of which we have just spoken. New connecting genera have been discovered, but still not a single identical species. Jukes, in his " Manual," published at the end of last year, says : " Near Maastricht, in Holland, the chalk, with flint, is covered by a kind of chalky rock, with gray flints, over which are loose, yellowish lime- stones, sometimes almost made up of fossils." Similar beds also occur at Saxoe in Denmark. Together with true creta- ceous fossils, such as pecten and quadricostatus, these beds contain species of the genera Voluta, Fasciolaria, Cyprea, Oliva, etc., etc., several of which GENERA are also found else- where in the Tertiary rocks. 1 Sir Roderick Murchison's late explorations in the Highlands although, of course, local in their character have made a 1 A doubt has, nevertheless, been expressed whether these are not bro- ken-up Tertinries. 3 INTRODUCTORY KKSt.Mi:: change in the GEOLOGY OF SCOTLAND. The next edition of the "Old li<-d Sandstone" will be the most fit- ting place to speak of these at length ; and I have some reason to believe that Sir Roderick himself will then favor me with a communication giving some account of them. Suffice it at present to say, that the supposed Old Red Conglomerate of the Western Highlands, as laid down in the year 1827 by Sir Roderick himself, accompanied by Professor Sedgwick, and so far acquiesced in by my husband, although he always wrote doubtfully on the subject, has now been ascertained to be, not Old Red, but Silurian. In Sir Roderick's last Address to the British Association, he says : " Professor Sedgwick and him- self had, thirty-one years ago, ascertained an ascending order from gneiss, covered by quartz rocks, with limestone, into ( vc Hying quartzose, micaceous, and other crystalline rocks, -oini' of which have a gneissose character. They had also observed what they supposed to be an associated formation of red grit and sandstone ; but the exact relations of this to the crystalline rocks was not ascertained, owing to bad weather. In the meantime, they, as well as all subsequent geologists, had erred in believing the great and lofty masses of purple and red conglomerate of the western coast were of the same age as on the east, and therefore 'Old Red Sandstone.' . . . Xicol had suggested that the quartzites and lime- stones illicit 1)0 the equivalent of the Carboniferous system of th- .-oiith of Sri>tl:md. Wholly dis-cnting from that hypoth- PROGRESS OF GEOLOGICAL SCIENCE. 27 esis, ho (Sir Roderick) had urged Mr. Peach to avail himself of his first leisure moments to reexamine the fossil-beds of Durness and Assynt, and the result was the discovery of so many forms of undoubted Lower Silurian characters (deter- mined by Mr. Salter), that the question has been completely set at rest there being now no less than nineteen or twenty species of M'Lurea, Murchisonia, Cephalita, and Orthoceras, with an Orthis, etc., of which ten or eleven occur in the Lower Silurian rocks of North America." This change would demand an entirely new map of the Geology of Scotland ; for there is clearly ascertained to be an ascending series from west to east, beginning with an older or primitive gneiss, on which a Cambrian conglomerate, and over that again a band containing the Silurian fossils, rest ; while a younger gneiss occupies a portion of the central nucleus, hav- ing the Old Red Sandstone series on the eastern side. A change has likewise been made in the internal arrangements of the Old Red, of which the next edition of my husband's work on the subject will be the proper place to speak in detail. In the meantime, I may just mention, that the Caithness and Cromarty beds have been found to occupy, not the lowest, but the central place, the lowest being assigned to the Forfar- ghire beds, containing Cephalaspis, associated with Pteraspis, an organism characteristically Silurian. That which bears most upon the subject before us, is the now perfectly ascer- 28 INTRODUCTORY RESUME : tained imprint of the footsteps of large reptiles in the Elgin or uppermost formation of the Old Red. A shade of doubt had rested upon the discovery made many years ago by Mr. Pat- rick DulF, of the Telerpeton Elginense, not as to the real nature of the fossil, which is indisputably a small lizard, but as to whether the stratum in which it was found belonged to the Old Red, or to the formation immediately above it. It will be observed, however, that the existence of reptiles in the Old Red did not rest altogether upon this, because the footprints of large animals of the same class had been ascertained in the United States of America. I cannot but conceive, therefore, that Mr. Duff, in a recent letter or paper read in Elgin, and published in the Elgin and MoraysJtire Courier, makes too much of the recent discoveries in his neighborhood, when he rtfl that the Old Red Sandstone had been hitherto -consid- ered exclusively a jish formation, and that the appearance of reptiles is altogether novel. " Now," says he, " that the Old Re.d Sandstones of Moray have acquired some celebrity, it may not be unprofitable to trace the different stages by which the discovery was arrived at of reptilian remains in that very ancient system, which till now was held to have been peopled by n higher order of beings than fs/tes." Mr. Duff forgets that in the programme, as it may be called, given by my husband, of the introduction of different types of animal life, as ascer- tainr.l in his d:iy. reptiles are made to occupy preci-ely the ion tln-y do now. To rci're.-h the memory of the reader, PROGRESS OF GEOLOGICAL SCIENCE. 29 I shall here reproduce it, as given in the " Testimony of the Rocks." At page 45 is this diagram : Silurian. Old Red. Carboniferous. Permian. Triassio. Oolitic. Cretaceous. Tertiary. Recent. .Had. Art. Mol. Fishes. Reptiles. Birds. Mam mala. Fla. Mam. i Man. Geologic [Rail. Art. Mol. Fish. Rep. Bird. Mam. Man.] arrangement. Cuvicr's [Rail. Art. Mol. Fish. Rep. Bird. Mam. Man.] arrangement. THE GENEALOGY OF ANIMALS And on the following page occurs this comment : " In the many-folded pages of the Old Red Sandstone, till we reach the highest and last, there occur the remains of no other verte- brates than those of this fourth class [fishes] ; but in its upper- most deposits there appear traces of the third or reptilian class ; and in passing upwards still, through the Carboniferous, Per- mian, and Triassic systems, we find reptiles continuing the master-existences of the time." And at page 104, express allusion is made to the Tclerpeton Elginense, with the doubt 3* SO INTRODUCTORY RESUME: a; !o tin- nature of its locale very slightly touched upon. 1 All tliis Mr. Duff has forgotten, apparently; and it appears like- wi-c not to have come within his cognizance that Sir Charles Lyell distinctly recognizes his Telerpeton, as well as the American foot-prints, antat-il. in an anonymous article published in a widely-circu- lated journal, 8 and in connection with the discovery of the KL'in reptile foot-prints, that Hugh Miller considered the Old U- d Satid-icnie to have been a shoreless ocean without a tree! 3 utterly ignoring the fact that he was himself the discoverer of the first Old Red fossil-wood of a coniferous character, and 1 Tli is doubt, I see by Sir Roderick Murchison's latest Address to the Association, is not yet entirely obviated. See pajre I _'_'. - For this article, as an excellent specimen of its elass, see pajrc 409, under the I ,1 Discoveries;" and, in contradistinction to it, the extract from Sir R. Murchison's Address otit gratification I have perused Sir Roderick's repeated assurances of to the "01,1 Li-ht." 8.-e Contra, p PROGRESS OF GEOLOGICAL SCIENCE. 31 that he thence expressly infers the then existence of vegetation of a high order. Is it not enough to add to the store of knowledge without attempting to undermine all that has gone before ? Must the discovery of an additional reptile, a few additional marsupials, be the signal for the immediate outcry, "All is changed; the former things have passed away; all things have become new ? " My husband was solicitous even to the point of nervous anxiety to exclude from his writings every particle of error, whether of facts, or of the conclusions to be drawn from them. Much rather would he never have written at all than feel himself in any degree a false teacher. " Truth first, come what may afterwards," was his invariable motto. In the same spirit, God enabling me, I have been desirous to carry on the publication of his posthumous writ- ings. God forbid that one entrusted with such sacred guar- dianship should seek to pervert or suppress a single truth, actual or presumptive, even though its evidence were to over- throw, in a single hour, all his much-loved speculations all his reasonings, so long cogitated, so conscientiously wrought ought Yet I must confess that I was at first startled and alarmed by rumors of changes and discoveries, which, I was told, were to overturn at once the science of Geology as hith- erto received, and all the evidences which had been drawn from it in favor of revealed religion. Though well persuaded that at all times, and by the most unexpected methods, the Most High is able to assert Himself, the proneness of man to make 32 INTRODUCTORY RESUME: use of every unoccupied position in order to maintain his independence of his Maker, seemed about to gain new vigor by acquiring a fresh vantage-ground. The old cry of the eternity of matter, and the " all things remain as they were Inn 11 the beginning until now," rung in my ears. God with us, in the world of science henceforth to be no more ! The very evidences of His being seemed about to be removed into a more distant and dimmer region, and a dreary swamp of infidelity spread onwards and backwards throughout the past eternity. Without stopping to inquire whether although the science of Geology had been revolutionized those fears were not altogether exaggerated, it is enough at present to know, that, as Geology has not been revolutionized, there is no need to entertain the question. I trust I have at least succeeded in furnishing the reader with such references few and simple when we once know where to find them as may enable him to decide upon this important matter for himself. If I have learned anything in the course of the investigations which I been endeavoring to make, it is to take nothing upon credence, but to wait patiently for all the evidence which can be brought to bear upon the subject before me; and this, I li'-lieve, is the only way to make any approximation to a cor- rect opinion. In truth, the science of Geology is itself in that condition, that no fact ought to be accepted as a basis for PROGRESS OF GEOLOGICAL SCIENCE. 33 reasoning of a solid kind, until it has run the round of investi- gation by the most competent authorities, and has stood the test of time. It is peculiarly subject to the cry of Lo, here ! and lo, there ! from false and imperfectly informed teachers ; and I .believe the men most thoroughly to be relied on are those who are the slowest to theorize, the last to form a judgment, and who require the largest amount of evidence before that judgment is finally pronounced. In addition to the inspection of my ever kind and generous friend Mr. Symonds, 1 1 have submitted the following pages to the reading of Mr. Geikie, 2 of the Geological Survey, who has here and there furnished a note. Of the amount and correct- ness of his knowledge, acquired chiefly in the field and in the course of his professional duties, my husband had formed the highest opinion. Indeed, I believe he looked upon him as the individual who would most probably be his successor as an exponent of Scottish Geology. One who walks, on an aver- age, twenty miles per day, and who has submitted nearly every rood of the soil to the accurate inspection demanded by the Survey, must be one whose opinion, in all that pertains to Scottish Geology in especial, must be well worth the having. I have to add an expression of most grateful thanks to Sir 1 The Rev. W. S. Symonds, author of " Old Stones," " Stones of the Valley," etc., and the compiler of the index to the recent edition of Sir R. Murchison's " Siluria." 2 Archibald Geikie, Esq., author of "The Story of a Boulder-" 34 INTRODUCTORY RESUME: Roderick Murchison, for his prompt attention to sundry appli. cations which I was constrained to make to him. His letters have been of the utmost importance in enabling me to perceive clearly the alterations which have taken place in our Scotti-h Geology, and the reasons for them. One feels instantaneously the benefit of contact with a master-mind. A few sentences, a few strokes of the pen, throw more light on the subject than volumes from an inferior hand. It remains now only to explain, that this course of Lec- tures, as delivered before the Philosophical Institution, con- sisted of eight, instead of six. Those now published are com- plete, according to their limits, in all that relates to the facts, literal or picturesque, of the subject; and the last two of the series will be found in " The Testimony of the Rocks," under the heads of" Geology in its Bearing on the Two Theologies," and "The Mosaic Vision of Creation." If it had been within the contemplation of the author to publish the six Lectures as they now stand, these last two would have formed their natural * climax or peroration. And, accordingly, I entertained some thought of republishing them here, in order that the reader might enjoy the advantage of having the whole under his eye at once. But, as they are not in any way necessary to the completion of the sense, and perhaps Geology, viewed simply by it-elf, and in the light of a popular study, is as well freed from extraneous matter, it was thought best, on the whole, to PROGRESS OF GEOLOGICAL SCIENCE. 85 refer the reader who wishes to see the eight discourses in their original connection, to " The Testimony of the Rocks." I have, instead, added an Appendix of rather a novel char- acter. In addition to the " Cruise of the Betsey," and " Ten* Thousand Miles over the Fossiliferous Deposits of Scotland," there was left a volume of papers unpublished as a whole, entitled " A Tour through the Northern Counties of Scotland." They had, however, been largely drawn upon in various other works ; but, scattered throughout were passages of more or less value, which I had not met with elsewhere ; and some such, of the descriptive kind, I have culled and arranged at the end of the Lectures : first, because I was loth that any original observation from that mind which should never think again for the instruction of others, should be lost, and also because many of those passages were of a kind which might prove suggestive to the student, and assist him in reasoning upon those phenom- ena of ordinary occurrence, without close observation of which no one can ever arrive at a successful interpretation of nature. If the reader should descry aught of repetition which has escaped my notice, I must crave his indulgence, in considera- tion of the very difficult and arduous task which God, in His mysterious providence, has allotted me. To endeavor to do by these writings as my husband himself would if he were yet with us to preserve the integrity of the text, and, in dealing with what is new, to bring to bear upon it the same unswerv- 36 INTRODUCTORY RESUME. ing rectitude of purpose in valuing and accepting every iota of truth, whether it can be explained or not, rejecting all that is crude, and abhorring all that is false, this has been my aim, although, alas ! too conscious throughout of the comparative feebleness of the powers brought to bear upon it. If, however, the reader is led to inquire for himself, 1 trust he will find that these powers, such as they are, have been used in no light or frivolous spirit, but with a deep, and somewhat of an adequate, sense of the vast importance of the subject. L. M. LECTURES ON GEOLOGY. LECTURE FIRST. Junction of Geologic and Human History Scottish History of Modern Date The Two Periods previous to the Roman Invasion; the Stone Age an;", the Bronze Age Geological Deposits of these Pre-historic Periods Tin Aboriginal Woods of Scotland Scotch Mosses consequences of the Roma:. Invasion How formed Deposits, Natural and Artificial, found under ther. The Sand Dunes of Scotland Human Remains and Works of Art fount: in them An Old Church Disinterred in 1835 on the Coast of Cornwall Controversy regarding it Ancient Scotch Barony underlying the Sand Th Old and New Coast Lines in Scotland Where chiefly to be observed Geol ogy the Science of Landscape Scenery of the Old and New Coast Lines Date of the Change of Level from the Old to the New Coast Line uncertain Beyond the Historic, but within the Human Period Evidences of the fact i:; remains of Primitive Weapons and Ancient Boats Changes of Level not rare- events to the Geologist Some of these enumerated The Boulder-Clay lt.< prevalence in the Lowlands of Scotland Indicated in the Scenery of the Country The Scratchiugs on the Boulders accounted for Produced by UK- grating of Icebergs when Scotland was submerged Direction in which Ice- bergs floated, from West to East " Crag and Tail the Eflect of it Probablj Cause of the Westerly Direction of the Current. Ix most of the countries of Western Europe, Scotland among the rest, geological history may be regarded as ending where human history begins. The most ancient portions of the one piece on to the most modern portion:: of the other. But their line of junction is, if I may so express myself, not an abrupt, but a shaded line ; so that, on the one hand, the human period passes so entirely into the geological, that we found our conclusions respecting 4 38 LECTURES ON GEOLOGY. the first human inhabitants rather on what they deemed geologic than on the ordinary historic data; and, on the other hand, some of the latter and lesser geologic changes have takrii place in periods comparatively so recent that, in even our own country, we are able to catch a glimpse of them in the first dawn of history proper, that written history in which man records the deeds of his fellows. In Scotland the ordinary historic materials are of no very ancient date. Ty tier's History opens with the acces- sion of Alexander III., in the middle of the thirteenth century ; the Annals of Lord Hailes commence nearly two centuries earlier, with the accession of Malcolm Canmore ; there still exist among the muniments of Durham Cathe- dral charters of the "gracious Duncan," written about the year 1035 ; and it is held by Runic scholars that the Anglo-Saxon inscription on the Ruthwell Cross may be about two centuries earlier still. But from beyond this comparatively ^modern period in Scotland no written docu- ment has descended, or no native inscription decipherable by the antiquary. A few votive tablets and altars, let- tered by the legionaries of Agricola or Lollius Urbicus, wlu'n engaged in laying down their long lines of wall, or rearing their watch-towers, represent a still remoter period ; and a few graphic passages in the classic pages of Tacitus throw a partial and fitful light on the forms and characters of the warlike people against which the ramparts were cast up, and for a time defended. But beyond this epoch, to at least the historian of the merely literary type, or to the antiquary of the purely documentary one, all is darkness. "At one stride comes the dark." The period once reached which we find so happily described by Coleridge. "Antecedently to all history," says the poet, " and long glimmering through it as a hazy tradition, there LECTURES ON GEOLOGY. 39 presents itself to our imagination an indefinite period, dateless as eternity, a state rather than a time. For even the sense of succession is lost in the uniformity of the stream." It is, however, more than probable that the age of Agric- ola holds but a midway place between the present time and the time in which Scotland first became a scene of human habitation. Two great periods had passed ere the period of the Roman invasion, that earliest period now known to the antiquary as tl^e " stone age" in which the metals were unknown, and to which the flint arrow-head and the greenstone battle-axe belong; and that after period known to the antiquary as the "bronze age" in which weapons of war and the chase were formed of a mixture of copper and tin. Bronze had, in the era of Agricola, been supplanted among the old Caledonians by iron, as stone had at an earlier era been supplanted by bronze ; and his legionaries were met in fight by men armed, much after the manner of their descendants at Sheriffmuir and Culloden, with broadsword and target. And it is known that nearly a century and a half earlier, when Caesar first crossed the Channel, the Britons used a money made of iron. The two earlier periods of bronze and stone had come to a close in the island ere the commencement of the Christian era; and our evidence regarding them is, as I have said, properly of a geologic character. We read their history in what may be termed the fossils of the antiquary. Man is peculiarly a tool-and- weapon-making animal ; and his tools and weapons repre- sent always the stage of civilization at which he has arrived. First, stone is the material out of which he fashions his implements. If we except that family of man which preserved the aboriginal civilization, there seems 10 LECTURES ON GEOLOGY. :iever to have been a tribe or nation that had not at one ;!me recourse to this most obvious of substances for their ' ools and weapons. Then comes an age in which stone is upplanted by the metals that occur in a native state, ; . e. in a state of ductility in the rock, such as copper, liver, and gold. Of these, copper is by much the most bundant; and in all countries in which it has been em- .iloyed for tools and weapons, means have been found by the primitive workers to harden it through an admixture of other metals, such as zinc ajid tin. Last of all, the com- paratively occult art of smelting iron is discovered, and -he further art of converting it into steel; and such is its superiority in this form to every other metal employed in the fabrication of implements, that it supplants every >ther ; and the battle-axe and chisel of hardened copper ' bronze) are as certainly superseded by it as the chisel and lie battle-axe of stone had at an earlier period been super- seded by the bronze. 1 Now, it is truly wonderful how thoroughly, for all general purposes, this scheme of classi- icatiou, which we owe to the Danish antiquary Thomson, oranges into corresponding sections and groups the an- 1 In an interesting article on Ireland which lately appeared in the ' Scotsman " newspaper, I find it stated that for a very considerable dis- :ince, " between Lough Rea and Lough Derg, the river Shannon was ford- ^ble at only one point, which of course formed the only medium of eom- nunication between the natives of the two banks. They seem, however," t is added, "to have met oftener for war than peace; and from this ford i whole series of ancient warlike weapons was dug out. These weapons ;re now preserved in the fine collection of antiquities in the Museum of lie Royal Irish Academy in Dublin, and are partly bronze and partly tone. Their position in the river bed told a curious tale, both historically ml geologically. The weapons of bronze were all found in the upper tratum, and below them those of stone; showing, as antiquaries well -now, that an age of bronze followed not an age of gold, but an age of ?tonc." LECTURES ON GEOLOGY. 41 tiquities of a country, and gives to it a legible history in ages unrecorded by the chronicler. With the stone tools or weapons there are found associated in our own country, for instance, a certain style of sepulture, a certain type of cranium, a certain form of human dwellings, a certain class of personal ornaments, certain rude log-hollowed canoes, undressed standing stones, and curiously-poised cromlechs. The bronze tool or weapon has also its associated class of antiquities, massive ornaments of gold, boats built of plank, and, as a modern shipwright would express himself, copper-fastened, cinerary urns, for it would seem that, while in an earlier, as in a later age, our country-folk buried their dead, in this middle period they committed their bodies to the flames ; and, withal, evidences, in the occasional productions of other countries, that commerce had begun to break up the death-like stagnation which characterized the earlier period, and to send through the nations its circulating tides, feeble of pulse and slow, but instinct, notwithstanding, with the first life of civilization. And thus we reason on the same kind of unwritten data regarding the human inhabitants of our country who li~v ed during these two early stages, as that on which we reason regarding their contemporaries the extirpated animals, or their predecessors the extinct ones. The interest which attaches to human history thus conducted on what may be termed the geologic plan is singularly great. No nation during its stone period possesses a literature ; nor did any nation, of at least Western Europe, possess a literature during its bronze period. Of course, without letters there can be no history ; and even if a detailed history of such uncivilized nations did exist, what would be its value? " Milton did not scruple to declare," says Hume, " that the skirmishes of kites or crows as much merited a particular 4* 42 LECTURES ON GEOLOGY. narrative as the confused transactions and battles of the Saxon Heptarchy." But the subject rises at once in dig-, nity and importance when, contemplating an ancient people through their remains, simply as men, we trace, step by step, the influence and character of their beliefs, their progress in the arts, the effects of invasion and conquest on both their minds and bodies, and, in short, the broad and general in their history, as opposed to the minute and the particular. The story of a civilized people I would fain study in the pages of their best and most philosophic historians; whereas I would prefer acquainting myself with that of a savage one archaeologically and in its re- mains. And I would appeal, in justification of the prefer- ence, to the great superiority in interest and value of the recently published " Pre-historic Annals of Scotland," by our accomplished townsman, Mr. Daniel Wilson, over all the diffuse narrative and tedious description of all the old chroniclers that ever wore out life in cloister or cell. What may be properly regarded as the geological de- posits or formations of the two pre-historic periods in Scotland, the period of stone and the period of bronze, are morasses, sand dunes, old river estuaries, and that marginal strip of flat land which intervenes between the ancient and the existing coast lines. The remains of man also occur, widely scattered all over the country, in a su- perficial layer, composed in some localities of the drift- travels, and in others of the boulder-clay; but to this stratum they do not geologically belong: they lie at a grave's depth, and have their place in it through the prev- alence of that almost instinctive feeling which led the patriarch of old to bury his dead out of his sight. Most of the mistakes, however, which would antedate the exist- of our species upon the earth, and make man con- LECTURES ON GEOLOGY. 43 temporary with the older extinct mammals, have resulted from this ancient practice of inhumation, or from accidents which have arisen out of it. All our Scotch morasses seem to be of comparatively modern origin. There are mosses in England, or at least buried forests, as on the Norfolk coast, at Cromer and Happisburgh, that are more ancient than the drift-clays and gravels ; whereas, so far as is yet known, there are none of our Scotch mosses that do not overlie the drift formations ; and not a few of their number seem to have been formed within even the historic ages. They are the memorials of a period, spread over many centuries, which began after Scotland had arisen out of the glacial ocean, and presented, under a softening climate, nearly the exist- ing area, but bore, in its continuous covering of forest, the indubitable signs of a virgin country. It is remarked by Humboldt, that all the earlier seats of civilization are bare and treeless. "When, in passing from our thickly foliated forests of oak, we cross," he says, " the Alps or the Pyr- enees, and enter Italy or Spain, or when the traveller first directs his eye to some of the African coasts of the Medi- terranean, he may be easily led to adopt the erroneous inference that absence of trees is a characteristic of the warmer climates. But he forgets," it is added, "that Southern Europe wore a different aspect when it was first colonized by Pelasgian or Carthaginian settlers. He for- gets, too, that an earlier civilization of the human race sets bounds to the increase of forests ; and that nations, in their change-loving spirit, gradually destroy the decora- tions which rejoice our eye in the north, and which, more than the records of history, attest the youthfulness of our civilization" Borne of my audience must be old enough to remember the last of the great aboriginal woods of 44 LECTURES ON GEOLOGY. Scotland. It was only during the second war of the first French Revolution, when the northern ports of Europe were shut against Great Britain, that the native pine- woods of Rothiemurchus and the upper reaches of the Spey were cut down; and as late as the year 1820, I looked, in the upper recesses of Strathcarron, on the last scattered remains of one of the most celebrated of the old pine-forests of Ross-shire. Possibly some of the frag- ments of the pine-forests which skirted the western shores of Loch Maree may still exist ; though, when I last passed through it, many years ago, the axe was busy among its glades. It is known of some of our Scotch mosses, the deposits which testify geologically to this primitive state of things when the country was forest-covered, that they date from the times of the Roman invasion, and were consequences of it. The mark of the Roman axe a narrow, chisel-like tool has been detected, in many in- stances, on the lower tier of stumps over which the peat has accumulated ; and in some cases the sorely rusted axe itself has been found sticking in the buried tree. Among ^ O O the tangled debris of a prostrated forest the woodman fre- quently mislays his tools, a mishap to which the old Romans seem to have been as subject as the men of a later time ; and so the list of Roman utensils, coins, and arms, found in the mosses of the south and midland parts of Scotland, is in consequence a long one. " In Pousil Moss, near Glasgow," says Rennie, in his "Essay on Peat Moss,"- " a leathern bag containing about two hundred silver coins of Rome was found ; in Dundaff Moor a number of simi- lar coins were found; in Annan Moss, near the Roman Causeway, a Roman ornament of pure gold was found ; a <-:mi].-kottle was found eight feet deep under a on the estate of (>rliu.-rt yn ; in Flanders Moss a LECTURES ON GEOLOGY. 45 similar utensil was found; a Roman jug was found in Locher Moss, Dumfriesshire; a pot and decanter of Ro- man copper was found in a moss in Kirkmichael parish, in the same county ; and two vessels of Roman bronze in the Moss of Glenderhill, in Strathaven." And thus the list runs on. It is not difficult to conceive how, in the circum- stances, mosses come to be formed. The Roman soldiers cut down, in their march, wide avenues in the forests through which they passed. The felled wood was left to rot on the surface ; small streams were choked up in the levels ; pools formed in the hollows ; the soil beneath, shut up from the light and the air, became unfitted to produce its former vegetation ; but a new order of plants, the thick water-mosses, began to spring up ; one generation budded and decayed over the ruins of another; and what had been an overturned forest became in the course of years a deep morass, an unsightly but permanent monument of the formidable invader. Some of our other Scotch mosses seem to have owed their origin to violent hurricanes; their under tier of trunks, either turned up by the roots or broken across, lie all one way. What may be termed their native fossils are exceedingly curious. I have seen personal ornaments of the stone period, chiefly beads of large size, made out of a pink-colored carbonate of lime, which had been found in the bed of gravel on which one of our Galwegian mosses rested, and which intimated that the " stone period " had commenced in the island ere this moss had begun to form. We find the same fact borne out by the Black Moss on the banks of the Etive, Argyleshire, where, under an accu- mulation of eight feet of peat, there occur irregularly oval pavements of stone, overlaid often by a layer of wood- ashes, and surrounded by portions of hazel stakes, the 16 LECTURES ON GEOLOGY. remains, apparently, of such primitive huts as those in which, according to Gihbon, the ancient Germans resided, ami which were, we are told, "of a circular figure, built of rough timber, thatched with straw, and pierced at the top, to leave a free, passage for the smoke." Similar re- mains, but apparently of a still more ancient type, have been laid open in Aberdeenshire ; and I find Mr. Wilson stating, in his archaeological history, that on several occa- sions, rude canoes, which had been hollowed out of single logs of wood by the agency of fire, and evidently of the " stone age," have been found in Lochar Moss, Dumfries- shire, with ornamental tores and brass bowls, not less evi- dently of the subsequent " bronze period." It is stated by Dr. Boates, in his " Natural History," that in Ireland, the furrows of what had been once ploughed fields have been found underlying bogs, in one instance at least (in Don- egal), with the remains of an ancientj)lough, and the wat- tles of a hedge six feet beneath the surface. In 1833 there discovered in Drumkilen bog, near the north-east coast of the county of Donegal, an ancient house formed of oak beams. Though only nine feet high, it consisted of two stories, each about four feet in height. One side of the building was entirely open, and a stone chisel was found on the floor, indicating that this ancient domicile belonged to the stone period. Associated, too, with the works of man of the earlier periods, we find in our mosses equally suggestive remains of the extirpated, and in some - of the extinct animals, such as gigantic skulls and horns of the Jios Primigenius or native ox, and of the Oer- vua Megaceros or Irish elk, with the skeletons of wolves, of beavers, of wild horses, and of bears. Then- c.\ i -t s what :is to be sufficient evidence that the two extinct ani- mals named the Irish elk and native ox were contemporary LECTURES ON GEOLOGY. 47 with the primitive hunters of the stone period : the cervi- cal vertebrae of a native ox have been found deeply scarred by a stone javelin, and the rib of an Irish elk perforated by a stone arrow-head ; and it is known that some of the extirpated animals, such as the wild horse, wolf, and bea- ver, continued to live among our forests down till a com- paratively recent period. 1 We find it stated by Hector Boece, in his " History," that there were beavers living among our Highland glens even in his days, as late as the year 1520; but there rests a shadow of doubt on the state- ment. It is unquestionable, however, that the Gaelic name of the creature, Lasleathin, or broad-tail, still sur- vives; and equally certain that when Baldwin, Arch- bishop of Canterbury, journeyed into Wales towards the close of the twelfth century, to incite the Welsh to join in the Crusades, the beaver was engaged in building its coffer domes and log-houses in the river Teivy, Cardigan- shire. The wolf and wild horse maintained their place in at least the northern part of the island for several centu- ries later. When in 1618 Taylor, the water poet, visited Scotland, he accompanied the " good lord of Mar " on one of his great hunting expeditions among the Grampians; and we find, from the amusing narrative of his journey, that for the space of twelve days he saw neither house nor corn-field, but "deer, wild horses, wolves, and such like creatures." The wolf did not finally disappear from among our mountains until the year 1680, when the last of the race was killed in Lochaber by that formidable Ewan Cameron of Lochiel with whom Cromwell was content to make peace after conquering all the rest of Scotland. 1 Many interesting human remains have latdy been disinterred from the Severn drift and gravels near Tcwkesbury, such as cinerary urns with bones and ashes, and utensils for carrying water, associated with antlers of the red deer. W. S. S. 48 LECTURES ON GEOLOGY. The sand dunes of the country accumulations of sand hrajied over the soil by the winds, and in some cases, as in the neighborhood of Stromness in Orkney, and near New Quay on the coast of Cornwall, consolidated into a kind of open-grained sandstone contain, like the mosses of the country, ancient human remains and works of art. There have been detected among the older sand dunes of Moray, broken or partially finished arrow-heads of flint, with splin- tered masses of the material out of which they had been fashioned, the debris, apparently, of the workshop of some weapon-maker of the stone period. Among a tract of sand dunes on the shores of the Cromarty Frith, imme- diately under the Northern Sutor, in a hillock of blown sand, which was laid open about eighty years ago by the winds of a stormy winter, there was found a pile of the bones of the various animals of the chase, and the horns of deer, mixed with the shells of molluscs of the edible species; and, judging from the remains of an ancient hill- fort in the neighborhood, and from the circumstance that under an adjacent dune rude sepulchral urns were dis- interred many years after, I have concluded that the hunt- ers by whom they had been accumulated could not have flourished later than at least the age of bronze. It was ascertained in one of the Orkneys, about the year 1819, that a range of similar dunes, partially cleared by a long tract of high winds from the west, had overlain for untold ages what seemed to be the remains of an ancient Scan- dinavian village. In fine, very strange fossils of the human period has this sand deposit of subaerial formation been found to contain. There were disinterred on the Cornish coast in 1835, out of an immense wreath of sand, an old British church and oratory, the church and oratory of Perr:m-s;il)iil;e, whirl) had been hidden from the eye of LECTURES ON GEOLOGY. 49 man for nearly a thousand years. The Tractarian contro- versy had just begun at the time to agitate the Episcopacy of England ; it had become of importance to ascertain the exact form of building sanctioned by antiquity as most conducive to devotion ; and a fossil church, which had un- dergone no change almost since the times of the ancient Christianity, was too interesting a relic to escape the notice of the parties which the controversy divided. But though antagonistic volumes were written regarding it, in a style not quite like that in which Professor Owen and Dr. Man- tell have since discussed the restoration of the Belemnite, it was ultimately found that the little old church of St. Pimm the Culdee such a building as Robinson Crusoe might have erected for the ecclesiastical uses of himself and his man Friday threw exceedingly little light on the vexed question of church architecture. The altar is in the east, said the Tractarians. Nay, the building itself does not lie east and west, replied their opponents. We grant you it does not, rejoined the Tractarians ; but its gable fronts the point where the sun rises on the saint's birthday. Who knows that? exclaimed their opponents : besides, the sacred gable was unfurnished with a window. We deny that, said the Tractarians; the laborer who saw it just ere it fell says there was a large hole in it. And thus the con- troversy ran on, undoubtedly amusing, and, I daresay, very instructive. The north of Scotland has its ancient fossil barony underlying a wilderness of sand ; ploughed fields and fences, with the walls of turf-cottages, and the remains of a manor-house, all irrecoverably submerged; and we find the fact recorded in a Scotch act of the times of Wil- liam III. Curious, as being perhaps the only act of Par- liament in existence to which the geologist could refer for the history. of a deposit, I must take the liberty of submit- 50 LECTURES ON GEOLOGY. ting to you a small portion of one of its long sentences. " Our Sovereign Lord," says the preamble, " considering that many lands, meadows, and pasturages, lying on the sea-coa.sts, have l>eeii ruined and overspread in many parts of thi kingdom by sand driven from sand-hills, the which has been mainly occasioned by the pulling up of the roots of bent, juniper, and broom bushes, which did loose and break the surface and scroof of the sand-hills ; and partic- ularly, considering that the barony of Cawbin, and house and yeards thereof, lying within the sheriffdom of Elgin, is quite ruined and overspread with sand, the which was oc- ca*sioned by the foresaid bad practice of pulling the bent and juniper, does hereby strictly prohibit," etc., etc., etc. I have wandered for hours amid the sand-wastes of this ruined barony, and seen only a few stunted bushes of broom, and a few scattered tufts of withered bent, occupy- ing, amid utter barrenness, the place of what, in the middle of the seventeenth century, had been the richest fields of the rich province of Moray; and, where the winds had hollowed out the sand, I have detected, uncovered for a few yards'-breadth, portions of the buried furrows, sorely dried into the consistence of sun-burned brick, but largely charged with the seeds of the common corn-field weeds of the country, that, as ascertained by experiment by the late Sir Thomas Dick Lauder, still retain their vitality. It is said that an antique dove-cot in front of the huge sand- wreath which enveloped the manor-house, continued to present the top of its peaked roof over the sand, as a foun- dered vessel sometimes exhibits its vane over the waves, until the year 1760. The traditions of the district testify that, for many years after the orchard had been enveloped, the topmost branches of the fruit-trees, barely seen over the surface, continued cadi spring languidly to throw out LECTURES ON GEOLOGY. 51 bud and blossom ; and it is a curious circumstance, that in the neighboring churchyard of Dike there is a sepulchral monument of the Culbin family, which, though it does not date beyond the reign of James VI., was erected by a lord and lady of the last barony, at a time when they seem to have had no suspicion of the utte*r ruin which was coming on their house. The quaint inscription runs as follows : VALER : KIJfNAIRD : ELIZABETH : IXXIS : 1613 : THE : BVILDAES : OF : THIS : BED : OP : STAKE : AE : LAIRD : AND : LADIE : OP : COVBIXE : QVHILK : TV A : AND : THAK8 : QVHANE : BRAITHE IS : GAXE : PLEIS : GOD : VIL : 8LEIP : THIS : BED : VITHIN : I refer to these facts, though they belong certainly to no very remote age in the past history of our country, chiefly to show that in what may be termed the geological forma- tions of the human period very curious fossils may be already deposited, awaiting the researches, of the future. As we now find, in raising blocks of stone from the quarry, water-rippled surfaces lying beneath, fretted by the tracks of ancient birds and reptiles, there is a time coming when, under thick beds of stone, there may be detected fields and orchards, cottages, ihanor-houses, and churches, the me- morials of nations that have perished, and of a condition of things and a stage of society that have forever passed away. Sand dunes and morasses are phenomena of a strictly local character. The last great geological change, general in its extent and effects, of which Scotland was the subject, was a change in its level, in relation to that of the ocean, of from fifteen to thirty feet. At some unascertained period, regarded as recent by the geologist, for man seems to have been an actor on the scene at the time, but remote 52 LECTURES ON GEOLOGY. by the historian, for its date is anterior to that of his oldest authorities in this country, the land rose, appar- ently during several interrupted paroxysms of upheaval, so that there was a fringe of comparatively level sea-bottom laid dry, and added to the country's area, considerably broader than that which we now see exposed by the ebb of every stream tide. And what I must deem indubitable marks of this change of level can be traced all around Scot- land and its islands. The country, save in a few interrupted tracts of precipitous coast, where the depth of the water, like that beside a steep mole whose base never dries at ebb, precluded any accession to the land, presents around its margin a double coast line, the line at present washed by the waves, and a line now covered with grass, or waving with shrubs, or skirted by walls of precipice perforated with caves, against which the surf broke for the last time more than two thousand years ago. These raised beaches form a peculiar feature in our Scottish scenery, which you must have often remarked. In passing along the public road be- tween Portobello and Leith, the traveller sees upon the left hand a continuous grassy bank, with a line of willows atop, which he may mark in some places advancing in low promontories, in others receding into shallow bays, and which is separated from the present coast line, which in general flatness it greatly resembles, by a strip of rich meadow land, varying from one to three hundred yards in breadth. The continuous grassy bank is the old coast line ; and the gently sloping margin of green meadow is the strip of flat sea-beach along which the tides used to rise and fall twice every twenty-four hours, ere the retreat of the sea within its present bounds. Should it be low ebb at the tiim-, one may pass from the ancient to the recent sea- l'f:it-h; the one waving with grass, the other brown with LECTURES ON GEOLOGY. 53 alga? ; the one consisting, under its covering of vegetable mould, of stratified gravels and sand, blent with the de- cayed shells of mollusca that died more than twenty cen- turies since ; the other formed of exactly the same sort of lines of stratified sand and gravel, and strewed over by shells that were thrown ashore by the last tide, and that lived only a few weeks ago. And, rising over the lower, as over the upper flat, we see a continuous escarpment, which marks where, in the present age, during the height of stream tides, the sea and the land meet ; just as the up- per willow-crested escarpment indicates where they met of old. The two escarpments and the two gently sloping planes at their base are repetitions of the same phenomena, save that the upper escarpment and upper plane are some- what softer in their outline than the lower, an effect of the wear of the elements, and of the accumulation of the vegetable mould. There is as thorough an identity between them as between two contiguous steps of a stair, covered, the one by a patch of brown, and the other by a patch of green, in the pattern of the stair-carpet. There are other parts of our Scottish shores in which the old coast line is of a much bolder character than anywhere in this* neigh- borhood, and the plane at its base of greater breadth. On the Forfarshire coast, the Dundee and Arbroath Railway runs along the level margin, once a sea-bottom, which at one point, opposite the parish church of Barrie, is at length two miles in breadth, and the old coast line rises from thirty to fifty feet over it. It is strongly marked on the southern side of the Dornoch Frith, immediately below and for sev- eral miles to the east of the town of Tain, where it attains a breadth of from one to two miles, and where the old sea- margin, rising over the cottage-mottled plain below in a series of jutting headlands, with green bosky bays between, 5* 54 LECTURES ON GEOLOGY. strikes even the least practised eye as possessed of all the characteristic peculiarities of a true coast line. It is scarce less marked in the neighborhood of Cromarty, and on the opposite shore of the Cromarty Frith, in the parish of Nigg. It runs along by much the greater portion of the eastern coast of Sutherland ; and forms at the head of Loch Fleet, in the neighborhood of Dornoch, a long withdrawing frith, bounded by picturesque shores, and covered by a short, green sward, level as the sea in a calm, on which groups tit' willow and alder trees take the place of busy fleets, and the hare and the partridge that of the coot and the por- poise. Along the upper recesses of almost all our flatter friths, such as the friths of Beauly, of Dingwall, and of the Tay, and of the Clyde, it exists as fertile tracts of carse- land ; the rich links of the Forth, rendered classical by the muse of Macneil, belong to it ; it furnishes, in various other localities more exposed to the open sea, ranges of sandy links of a less valuable character, such as the range in our own neighborhood occupied by the race-course of Inveresk; and not a few of the seaports and watering places of the country, such as the greater part of Leitli, Portobello, .Mii>.selburgh, Kirkaldy, Dundee, Dingwall, Invergordon, Cromarty, Wick, Thurso, Kirkwall, Oban, and Greenock, have been built upon it. The old coast line, with the flat marginal selvage at its base, form, as I have said, well-marked features in the scenery of the island. Geology may be properly regarded us the wience of landscape: it is to the landscape painte' what anatomy is to the historic one or to the sculptor. T the singularly rich and variously compounded prospects of our country there is scarce a single trait that cannot be resolved into some geological peculiarity in the coun- t'r.ui:. u..ik, or which does not bear witness otherwise LECTURES OX GEOLOGY. 55 and more directly than from any mere suggestion of the associative faculty, to some striking event in its physical history. Its landscapes are tablets roughened, like the tablets of Nineveh, with the records of the past ; and their various features, whether of hill or valley, terrace or escarp- ment, form the bold and graceful characters in which the narrative is inscribed. As our Scottish geologists have given less attention to this special department of their science than to perhaps any other, less, I am disposed to think, than, from its intrinsic interest and its bearing on art, is fairly owing to it, I shall take the liberty cast- ing myself on the forbearance of such of my audience as are least artistic in their tastes of occasionally touching upon it in my course. I need scarce refer to the scenery of our mosses, these sombre, lake-like tracts, divested, however, of the cheerful gleam of the water,- that so often fatigue the eye of the traveller among our mountains, but which at that season when the white cottony carnach mottles their dark sur- faces, reminding one of tears on a hatchment, when the hills around, purple with the richly- blossoming heath, are chequered with the light and shade of a cloud-dappled sky, and when, in-'the rough foreground, the gray upright stone of other days waves its beard of long gray lichen to the breeze, are not unworthy, in their impressive loneli- ness, of employing, as they have oftener than once done, the magic pencil of a Macculloch. I need as little refer to the scenery of those sand dunes which gleam so brightly amid some of our northern landscapes, and which, not only in color, but also in form, contrast so strongly with our morasses. The dark flat morass is suggestive always of sluggish and stagnant repose ; whereas, among our sand dunes, from the minuter ripple-markings of the general 56 LECTURES ON GEOLOGY. surface to the wave-like form of the hills sloped in the direction of the prevailing winds, and curved, like snow- wreaths, to the opposite point of the compass, almost every outline is equally suggestive of motion. I could, however, fain borrow the pencil of our countryman Hill, as he em- ploys it in his exquisite cabinet-pictures, to portray the story of the last Barony: rolling hills of sand all around, the red light of a stormy summer evening deepening into dun and lurid brown, through an eddying column of suf- focating dust snatched up by a whirlwind ; the antique garden-dial dimly shadowing forth the hour of sunset for the last time, nmid half-submerged shrubs and trees ; and, full in the centre of the picture, a forlorn fortalice of the olden time, with the encroaching wreath rising to its lower battlements, like some wrecked vessel on a. wild lee-shore, with the angry surf raging high over her deck, and kissing with its flame-like tips the distant yards. The scenery of the old coast line possesses well-nigh all the variety of that of the existing coast ; but it substitutes field and meadow for the blue sea, and woods and human dwellings for busy mast-crowded harbors,' and fleets riding at anchor. It is pleasing, however, to see headland jutting out beyond headland into some rich plain, traversed by trim hedge-rows and green lanes ; or some picturesque cottage, overshadowed by its gnarled elm, rising in some bosky hollow at the foot of the swelling bank or weather- stained precipice, beneath which the restless surf once broke against the beach. There are well-marked speci- mens of this scenery of the ancient coast line in our imme- diate neighborhood. Musselburgh, with its homely Saxon name, lies in the middle of what was once a flat sandy bay, no\v l:iid out into fields, gardens, and a race-course; :ml ll:r old coast escarpment, luxuriant with hanging woods, LECTURES ON GEOLOGY. 57 and gay with villas, and which may possibly have been its first Celtic designation, Inveresk, ere the last upheaval of the land, half closes around it. The church and burying- ground occupy the top of a long ridge, that had once been a river-bar, heaped up apparently by the action of the waves on the one side, and by that of the stream on the other. But, as shown by the remains of Roman baths and a Roman rampart, which once occupied its summit, it must have borne its present character from at least the times of Lollius Urbicus, perhaps for several centuries earlier. The neighboring port of Portobello, as seen from the east, just as it comes full in sight on the Musselburgh road, seems set so completely in a framework of the ancient escarpment, that it derives from it its natural features. But it is where, along our boulder shores, lines of steep precipices have been elevated over the sea, so that the waves no longer reach their bases, that the old coast sce- nery is at once most striking and peculiar. Tall picturesque stacks, which had once stood up amid the surf, brown and shaggy with the serrated fucus and the broad-fronded lam- inara, now rise out of thickets of fern or sloethorn, and wave green with glassy ivy and the pendant honeysuckle. Deep caverns, too, in which the billows had toiled for ages, but now silent, save when the drop tinkles from above into some cool cistern half hidden in the gloom of the interior, open along the wall of cliffs ; and over projecting buttresses of rock, perforated often at their bases as if by Gothic archways, and thickly mantled over by liverworts, green and gray, the birch hangs tremulous from above, or the hazel shoots out its boughs of brighter green, or the moun- tain-ash hangs its scarlet berries. One of the most pleasing landscapes of one of the most accomplished of female artists Miss Stoddart has as its subject an ancient 58 LECTURES ON GEOLOGY. escarpment of this bold character, which occurs in Arran. A mossy, fern-tufted meadow, skirted by the sea, roughened by what had once been half-tide skerries, and enlivened by a Highland cottage, stretches out into the foreground from an irregular wall of rock, overhung by graceful foli- age, hollowed into deep recesses, adown which the waters tinkle, and with some of its bolder projections perforated at the base like flying buttresses of the decorated Gothic ; and such is the truth of the representation, that we at once determine that the artist had chosen as her subject one of the more precipitous reaches of the old coast line, and that its wall of rock must have derived much of the peculiarity of trait so happily caught, from the action of the waves. Again, in direct contrast with this striking type of old coast escarpment, though in its own way not less striking, Mr. Hill's fine picture, " The Sands at Sunrise," lately engraved by the Art Union, exhibits as its background one of those long, flat, sandy spits, products of the last upheaval, which, stretching far into the sea, bear amid the light of day an air of even deeper loneliness than our woods and fields when embrowned by the gather- ing night. When the insulated stacks of an old coast line are at once tall and attenuated, and of a white or pale- colored rock, the effect, especially when viewed by moon- light, is singularly striking. The valley of the Seine, as described by Sir Charles Lyell, now a valley, but once a broad frith, is flanked on each side, in its lower reaches, by tall stacks of white chalk, of apparently the same age as those of the ancient coast line of our own country ; and, seen ranged along their green hill-sides, in the imper- fect light of evening, or by the rising moon, they seem the sheeted spectres of some extinct tribe of giants. The date of that change of level which gave to Scot- LECTURES ON GEOLOGY. 59 land this flat fringe of margin-land, with its picturesque es- carpment of ancient coast, we cannot positively fix. We find reason to conclude that it took place previous to the age of the Roman invasion. It has been shown, from evidence of a semi-geologic, semi-archasologic character, by one of our highest authorities on the subject, Mr. Smith of Jor- danhill, that the land must have stood at a not lower level than now, when the Roman wall which connects the friths of Forth and Clyde was completed. For, had it been otherwise, some of the terminal works which remain would have been, what they obviously were not, under the sea line at the time. In the sister kingdom, too, which has also its old coast line, St. Michael's Mount in Cornwall, which was connected with the mainland at low water by a strip of beach in the times of Julius Caesar, a fact recorded by Diodorus Siculus, is similarly connected with the mainland at low water still. But though the upheaval of the old coast line is removed thus beyond the historic period, it seems to have fallen, as I have said, within the human one : man seems to have been an inhab- itant of the island when its general level was from twenty to forty feet lower than now, and the waves broke at full tide against the old -coast line. "The skeleton of a Bala3- noptera," says Professor Owen, "seventy-two feet in length, was found," about thirty years ago, " imbedded in the clay on the banks of the Forth, more than twenty feet above the reach of the highest tide." And again, " Several bones of a whale," 1 he continues, "were also discovered at Dun- more rock, Stirlingshire, in brick-earth,' nearly forty feet above the present sea-level." These whales must have been stranded when the old coast line was washed by the 1 Eones of the whale have been found in the clay of the Avon and Severn drifts, in a similar ]>o -iiion. W. S. S. CO LECTURES ON GEOLOGY. waves, and the marginal strip existed as an oozy sea-bot- tom ; and yet in both cases there were found, among the bones, primitive weapons made of the pointed branches of deer's horns, hollowed at their broad ends by artificial perforations; and in one of these perforations the decayed fragments of a wooden shaft still remained. The pointed and perforated pieces of horn were evidently rude lance- heads, that in all probability had been employed against the stranded cetacea by the savage natives. Further, where the city of Glasgow now stands, three ancient boats one of which may be seen in the Museum of our Scottish Antiquaries in Edinburgh, and another in the Andersonian Museum have been dug up since the year 1781 ; the last only four years ago. One of the number was found a full quarter of a mile from the Clyde, and about twenty-six feet above its level at high water. It reposed, too, not on a laminated silt, such as the river now deposits, but on a pure sea sand. "It therefore appears," says Mr. Robert Chambers, in his singularly ingenious work on "Raised Beaches," "that we have scarcely an alternative to the supposition that when these vessels foundered, and were deposited where in modern times they have been found, the Frith of Clyde was a sea several miles wide at Glasgow, covering the site of the lower districts of the city, and receiving the waters of the river not lower than Both well Bridge." I may add, that the Glasgow boat in the Anti- quarian Museum is such a rude canoe, hollowed out of a single trunk, as may be seen in use among such of the Polynesian islands as lie most out of the reach of civiliza- tion, or in the Indian Archipelago, among the rude Alforian races; and that in another of these boats the first dis- covered there was found a beautifully polished hatchet of dark greenstone, an unequivocal indication that they LECTURES ON GEOLOGY. 61 belonged to the "stone period." There are curious ety- mologies traceable among the older Celtic names of places in the country, which I have sometimes heard adduced in evidence that it was inhabited, ere the last upheaval of the land, by the ancient Gaelic-speaking race. Eminences that rise in the flat marginal strip, and which, though islands once, could not have been such since the final recession of the sea, continue to bear, as in the neighborhood of Stir- ling, the Gaelic prefix for an island. But as the old Celts seem to have been remarkable as a people for their nice perception of resemblances, the insular form of these emi- nences may be perhaps regarded as suggestive enough to account for their names. One of these etymologies, how- ever, which could scarce have been founded on any mere resemblance, seems worthy of special notice. Loch Ewe, in Ross-shire, one of our salt sea lochs, receives the waters of Loch Maree, a noble fresh-water lake, about eighteen miles in length, so little raised above the sea-level, that ere the last upheaval of the land it must have formed merely the upper reaches of Loch Ewe. The name Loch Maree Mary's Loch is evidently mediaeval. And, curi- ously enough, about a mile beyond its upper end, just where Loch Ewe would have terminated ere the land last arose, an ancient farm has borne from time immemo- rial the name of Kinlochewe, the head of Loch Ewe. Dispose, however, of the etymologies as we may, there are facts enough on record which render it more than probable that, though the general change of level to which we owe the old coast line in Scotland does not lie within the his- toric ages, it is comprised within the human period. But we cannot, as has been shown, fix upon a date for the event. Were the case otherwise, could we fix with any cer- 6 62 LECTURES OX GEOLOGY. tainty the time when this change of level took place, and the platform of the lower coast line was gained from the sea, there might be an approximation made to the ante- rior space of time during which the line of high water had been the ' willow-crowned escarpment beyond Portobello and the green bank near Rutherglen, and the sea rose far beyond its present limits in our friths and bays. There are portions of the coast that at this early period presented* to the waves lines of precipices that are now fringed at their bases by strips of verdure, and removed far beyond their reach. There are other portions of coast in the immediate neighborhood of these, where similar lines of precipices, identical in their powers of resistance, were brought by the same movement within that very influence of the waves beyond which the others had been raised. And each line bears, in the caves with which it is fretted, caves hollowed by the attrition of the surf in the direc- tion of faults, or where masses of yielding texture had been included in the solid rock, indices to mark, propor- tionally at least, the respective periods during which they were exposed to the excavating agent. Thus, the aver- age depth of the ancient caves in an exposed line of coast, as ascertained by dividing the aggregate sum of their depths by their number, and the average depth, ascertained by the same process, of the recent caves, equally exposed on the same coast, and hollowed in the same variety of rock, could scarce fail to represent their respective periods of exposure, had we but a given number of years, histor- ically determined, to set off against the average measure- ment of the recent excavations. Even wanting that, how- ever, it is something to know, that though the sea has stood* at the existing sea-margin since the days of Agric- <>l:i, Miid ;it least a few centuries more, it stood for a con- LECTURES ON GEOLOGY. 63 siderably longer period at the old const line. The rock of which those remarkable promontories, the Sutors of Crornarty, are composed, is a granite gneiss, much trav- ersed by faults, and inclosing occasional masses of a soft chloride schist, that yields to the waves, while the sur- rounding gneiss hard enough to strike fire with steel remains little affected by the attrition of centuries. These promontories have, in consequence, their numerous caves ranged in a double row, the lower row that of the exist- ing const, the upper that of the old one ; and I have examined both rows with some little degree of care. The deepest of the recent caves measures, from the opening to its inner extremity, where the rock closes, exactly a hun- dred feet ; the deepest of the ancient ones, now so com- pletely raised above the surf, that in the highest tides, and urged upwards by the severest storms, the waves never reach its mouth, measures exactly a hundred and fifty feet. And these depths, though much beyond the respective average depths of their several rows, bear, so far as I could ascertain the point, the proportions to each other that these averages bear. The caves of the existing coast line are as two in depth, and those of the old coast line as three. If the excavation of the recent caves be the work of two thousand years, the excavation of the ancient caves must have been the work of three thousand ; or, as two thou- sand does not bring us much beyond the Roman period, let us assume as the period of the existing coast line and its caves, two thousand two hundred years, and as the proportional period of the old coast line, three thousand three hundred more. Both sums united bring us back five thousand five hundred years. How much more an- cient either coast line may be, we of course cannot deter- mine : we only know that, on the lowest possible assump- 64 LECTURES ON GEOLOGY. tion, we reach a period represented by their united ages only less extended by six years than that which the Sa- maritan chronology assumes as the period during which man has existed upon earth, and only three hundred and fifty-five years less than that assumed by the Masoretic chronology. The chronology of the Septuagint, which many have begun to deem the most adequate of the three, adds about five hundred and eighty-six years to the sum of the latter. Permit me, in closing this part of my subject, to show you that changes of level such as that to which we owe our old coast line in Scotland, and the marginal strip of dry land which we have laid out into so many pleasant gardens and fields, and on which we have built so many of our seaport towns, are by no means very rare events to the geologist. He enumerates at least five localities in the Old World, Scandinavia, part of the west coast of Italy, the coasts of Cutch and of Arracan, and part of the kingdom of Luzan, in which the level is slowly changing at the present time ; and in the New World there are vast districts in which the land suddenly changed its level for a higher one during the present century. "On the 19th of November 1822," says Sir Charles Lyell, " the coast of Chili was visited by a most disastrous earthquake. When the district around Valparaiso was examjned on the morn- ing after the shock, it was found that the whole line of coast for the distance of above one hundred miles was raised above its former level. At Valparaiso the elevation was three feet, and at Quinteno about four feet. Part of* the bed of the sea remained bare and drv at high water, * with beds of oyster, mussel, and other shells, adhering to the rocks on which they grew, the fish being all dead, and exhaling offensive effluvia." Again, on the east side LECTURES ON GEOLOGY. 65 of the Bay of Bengal, upon the coast of Arracan, which is at present in the course of rising, there are islands which present on their shores exactly such an appearance as our own country would have presented some sixty or a hun- dred years after the elevation of the old coast line. The island of Reguain, one of these, was carefully surveyed in the year 1841 by the officers of her Majesty's brig Chil- ders : and it has been carefully mapped in the admirable Physical Atlas of the Messrs. Johnston of Edinburgh. We find it, as shown in the map, resembling three islands ; the one placed within the other, as, to employ a homely illustration, the druggist, to save room, places his empty pill-boxes the one within the other. First, in the centre, there is the ancient island, with a well-defined coast line, some six or eight feet high, running all around it. At the base of this line there is a level sea of rich paddy fields, for what may be termed the second island has been all brought into cultivation; and it has also its coast line, which descends some six or eight feet more, to the level of a third island, which was elevated over the 'sea not more than eighty years ago, and which is still unculti- vated ; and the third island is surrounded by the existing coast line. Thus the centre island of Reguain consists of three great steps or platforms, each of which marks a par- oxysm of elevation ; and, with the upheaval of the coast of Chili, and a numerous class of events of a similar char- acter, it enables us to conceive of the last great geological change of which our country was the subject. We imag- ine a forest-covered land, marked by the bold, command- ing features by which we recognize our country, but in- habited by barbarous, half-naked tribes, that dwell in rude circular wigwams, formed of the branches of trees, that employ in war or the chase weapons of flint or jasper, 6* G6 LECTURES ON GEOLOGY. and that navigate their rivers or estuaries in canoes hollowed by fire out of single logs of wood. There has been an earthquake during the night; and when morning rises, the beach shows its broad, darkened strip of apparent ebb, though the tide is at full at the time ; and when the waters retire, they leave vast uncovered tracts never seen before, comparatively barren in sea-weed, but rich in stony nulliparite encrustations, minute coralines, and fleshy sponges. Ages elapse, and civilization grows. The added belt of level land is occupied to its utmost extent by man : lie lays it out into gardens and fields, and builds himself a dwelling upon it : but no sooner has he rendered it of some value, than the sea commences with him a course of tedious litigation for the recovery of its property ; and bit by bit has it been wresting it out of his hands. Almost all those tracts on our coasts which have been suffering during the last few centuries from the encroachment of the waves, and which have to be protected against their fury wherever land is valuable, as in this neighborhood, by lines of bulwarks, belong to the flat marginal strip won from them by the last change of level. Our next great incident in the geologic history of Scot- laud dates, it would seem, beyond the human period. In passing along the beach between Musselburgh and Porto- bello, or again between Portobello and Leith, or yet again between Leith and Newhaven, one sees an exceedingly stiff, dark-colored clay, charged with rounded pebbles and boulders, and which, where washed by the waves, presents a frontage nearly as steep as that of the rock itself. The deposit by which it is represented is known technically to the agriculturist as Till, and to the geologist as the Boul- der-Clay. Though not continuous, it is of very general occurrence, in the Lowlands of Scotland, and presents, LECTURES ON GEOLOGY. 67 though it varies in color and composition, according to the nature of the rocks which it overlies, certain unique ap- pearances, which seem to connect its origin in the several localities with one set of causes, and which no other deposit presents. Like the raised beaches, it has contrib- uted its distinctive quota to the variously featured scenery of our country. The Scottish word scaur, in the restricted significancy attached to it in many parts of the kingdom, means simply a precipice of clay; and it is almost invari- ably the boulder-clay that forms scaurs in Scotland; for it is one of the peculiarities of the deposit, that it stands up well-nigh as steeply over the sides of rivers, or on encroaching sea-beaches, or on abrupt hill-sides, as rock itself; and these clay precipices bear almost invariably a peculiar set of characters of their own. In some cases they spring up as square and mural, seen in front, as cliffs of the chalk, but seen in profile, we find their outlines described by parabolic curves. In other cases we see the vegetable mould rendered coherent by the roots of shrubs and grasses projecting over them atop, like the cornice of some edifice over its frieze. In yet other cases, though abrupt as precipices of solid rock, we find them seamed by the weather into numerous divergent channels, with py- ramidal peaks between ; and, thus combining the perpen- dicularity of true cliffs with the rain-scooped furrows of a yielding soil, they present eccentricities of aspect which strike, by their grotesqueness, eyes little accustomed to detect the picturesque in landscape. Such are some of the features of the scaurs of our country, a well-marked class of precipices for which the English language has no name. It is, however, in continuous grass-covered escarp- ments, which in some parts form the old coast line, and rise in others along the sides of rivers, that we detect at 68 LECTURES ON GEOLOGY. once the most marked and most graceful scenic peculiarity of the boulder-clay. The steep slopes, furrowed by enor- mous flutings, like those of the antique Doric, appear as if laid out into such burial-mounds as those with which a m frets the surface of a country churchyard, but with tliis difference, that they seem the burial-mounds of giants tall and bulky as those that of old warred against the gods. On a grass-covered escarpment of the boulder-clay in the neighborhood of Cromarty these mounds are strik- ing enough to have caught the eye of the children of the place, and are known among them as the giants' graves. They lie against the green bank, each from forty to sixty yards in length, and from six to ten yards in height, with their feet to the shore, and their heads on the top of the escarpment ; and when the evening sun falls low, and the shadows lengthen, they form, from their alternate bars of light and shade, that remind one of the ebon and ivory buttress of the poet, a singularly pleasing feature in the landscape. I have sometimes wished I could fix their fea- luivs in a calotypc, for the benefit of my friends the land- scape painters. This vignette, I would fain say, represents the boulder-clay after its precipitous banks worn down, by the frosts and rains of centuries, into parallel runnels, that gradually widened into these hollow grooves had sunk into the angle of inclination at which the disintegrat- ing agents ceased to operate, and the green sward covered all up. You must be studying these peculiarities of aspect more than ever you studied them before. There is a time coming when the connoisseur will as rigidly demand the specific character of the various geologic deposits in your rocks and scaurs, as- he now demands specific character in your shrubs and trees. I have said that the boulder-clay exhibits certain unique LECTURES ON GEOLOGY. 69 appearances, which connect its origin in the several locali- ties with one set of causes, and which no other deposit presents. On examining the boulders which it encloses, we find them strongly scarred and scratched. In most instances, too, the rock on which the clay rests, if it be a trap, or a limestone, or a finely-grained sandstone, or, in short, any rock on which a tool could act, and of a texture fitted to retain the mark of the tool, we find similarly scarred, grooved, and scratched. In this part of the country, the boulder-clay contains scarce any fossils, save fragments of the older organisms derived from the rocks beneath ; but in both the north and south of Scotland in Caithness, for instance, and in "Wigtonshire it con- tains numerous shells, which, both in their species and their state of keeping, throw light on the origin of the formation. But of that more anon. Let me first remark, that the materials of the level marginal strip of ancient sea-beach beneath the old coast line seem, like the mate- rials of the existing sea-beach, to have been arranged wholly by the agency of water. But in the boulder-clay we find a class of appearances which mere water could not have produced. Not only are the larger pebbles and boulders of the deposit scratched and grooved, but also its smaller stones, of from a few pounds to but a few ounces, or even less than an ounce, in weight ; and this, too, in a peculiar style and direction. When the stones are de- cidedly of an oblong or spindle shape, the scratchings occur, in at least four cases out of every five, in the line of their longer axis. Now, the agent which produced such effects could not have been simply water, whether im- pelled by currents or in waves. The blacksmith, let him use what strength of arm he may, cannot bring his file to bear upon a minute pin until he has first locked it fast in 70 LECTURES ON GEOLOGY. his vice ; and then, though not before, his tool bears upon it, and scratches it as deeply as if it were a beam of iron of a ton weight. The smaller stones must have been fastened before they could have been scratched. Even, however, if the force of water could have scratched and furrowed them, it would not have scratched and furrowed them longitudinally, but across. Stones, when carried adown a stream by the torrent, or propelled upwards along a beach by the waves, present always their broader and longer surfaces ; and the broader and longer these surfaces arc, the further are the stones propelled. They are not launched forwards, as a sailor would say, end on, but tum- bled forwards broadside. They come rolling down a river in flood, or upwards on the shore in a time of tempest, as a hogshead rolls down a declivity. In the boulder-clay, on the contrary, most of the pebbles that bear the mark of their transport at all Avere not rolled, but slidden for- ward in the line of their longer axis. They were launch' !, as ships are launched, in the line of least resistance, or as an arrow or javelin is sent on its course through the air. .Water could not have been the agent here, nor yet an eruption of mud, propelled along the surface by some wave of translation, produced by the sudden upheaval of the bottom of the sea, or by some great wave raised by an earthquake. But if water or an eruption of mud could not have pro- duced such effects as the longitudinal scratching, let us ask what could have produced them ? There are various pro- cesses going on around us, by which the scratchings on the solid rocks beneath are occasionally simulated with a less or greater degree of exactness. In some of our shallow 1 1 ighland fields, for instance, I have seen the rock beneath, or the stones buried at the depth of but a few inches from LECTURES OX GEOLOGY. 71 the surface, scarred by the plough with ruts not very unlike the larger ones on the stones and rocks of the boulder-clay; but in these plough-scarred surfaces the polish is wanting. Again, in some of our steeper lanes, if a fine-grained trap has been used in the pavement, we find that it soon polishes and wears down under the iron-armed feet of the passengers, and becomes scratched in the line of their tread, in a style not very distinguishable, save for the absence of the deeper furrows, from that of the scratched and polished rock-pavements of the boulder, clay. But I know of only one process by which, on a small scale, all the phenomena of the boulder-clay could be produced, mere especially, however, the phenomena of its oblong pebbles scratched in the lines of their longer axis ; and my recollection of that one dates a good mdtiy years back. When, more than a quarter of a century ago, the herring fishery began to be prosecuted with vigor in the north of Scotland, many of the Highland woods of natural birch and alder were cut down for the manufacture of barrels, and floated in rafts along the rivers to the sea. And my opportunities of observing these rafts, as they shot along the more rapid reaches of our mountain streams, or swept over their 'shallower ledges, grazing the bottom as they passed, naturally led me to inquire into their oper- ations upon the beds of the streams adown which they were floated. Let us advert to some of these. When a large raft of wood, floated down a rapid river, grates heavily over some shallow bank of gravel and pebbles resting on the rock beneath, it communicates motion, not of the rolling, but of the lurching character, to the flatter stones with which it comes in contact. It slides ponder- ously over them; and they, with a speed diminished in ratio from that of the moving power in proportion to the 72 LECTURES ON GEOLOGY. degree of friction below or around, slide over the stones or rock immediately, beneath. And thus, to borrow my terminology from our Scotch law courts, they are con verted at once into scratchers and scratchees. They are scratched by the grating, sand-armed raft, which of course moves quicker than they move ; and they scratch, in turn, the solid mass or embedded fragment along which they are launched. Further, if the gravelly shoals of the stream have, as is not uncommon in the shallows of our Highland rivers, their thickly-set patches of pearl mussels, many of these could scarce miss being crushed and broken ; and we would find not a few of their fragments, if much subjected to the friction of the rafting process, rounded at their edges, and mayhap scratched and polished like the stones. Nor is it difficult to conceive of a yet further consequence of the process. A vast number of rafts dropping down some river, from day to day and year to year, and always grating along the same ledges of sand- stone, trap, or shale, would at length very considerably wear them down ; and the materials of the waste, more or less argillaceous, according to the quality of the rock, would be deposited by the current in the pools and gentler reaches of the stream below. Even the continual tread of human feet in a crowded thoroughfare soon wears down the trap or sandstone pavement, and converts the solid stone into impalpable mud. Further, the color of the mud or clay would correspond, as in the thoroaghfare or public road, with the color of the rocks or stones which had been grooved down to form it; and there would occasionally mingle in the mass thus originated, rounded fragments of shells and pebbles, scratched in the line of their longer axis. Xo\v, in the boulder-clay wo find all these peculiarities LECTURES ON GEOLOGY. 73 remarkably exemplified. It contains, as has been shown, the oblong stones scratched longitudinally; we find it thickly charged in various parts of Scotland, though not in our own immediate neighborhood, with worn and rounded fragments of broken, shells ; and we see it almost invaria- bly borrowing its color from the rocks on which it rests, a consequence, apparently, of its being the dressings of these rocks. There is a peculiar kind of clay which forms on the surface of a hearthstone or piece of pavement, under the hands of a mason's laborer engaged in rubbing it sraooth with water and a polisher of gritty sandstone. This clay varies in quality and color with the character of the stone operated upon. A flag of Arbroath pavement yields a bluish-colored clay ; a flag of the Old Red of Ross or Forfarshire, a reddish colored clay; a flag of Suther- landshire Oolite, or of the Upper Old Red of Moray or of Fife, a pale yellowish clay. The polishing process is a process which produces clay out of stones, as various in tint as the coloring of the various stones which yield it ; and in almost every instance does the clay thus formed resemble some known variety of the boulder-clay. The boulder-clay, in the great majority of cases, is, both in color and quality, just such a clay as might be produced by this recipe of the mason's laborer, from the rocks on which it rests. The red sandstone rocks of Moray, Cro- marty, and Ross, are covered by red boulder-clays; a similar red boulder-clay, overlies the red sandstone rocks of Forfarshire; and I. was first apprised, when travelling in Banffshire some years ago, that I had entered on the dis- trict of the Old Red, by finding the boulder-clay assuming the familiar brick-red hue. Over the pale Oolites of Suth- erlandshire, as at Brora and Golspie, it is of a pale yellow tint, and of a yellowish red over the pale Old Red Sand- 7 74 LECTURES ON GEOLOGY. stones of the long, flat valley known as the Howe of P^ife. Again, in the middle and north-western districts of Caith- ness, where the paving flagstones so well known in com- merce give to the prevailing rocks of the district a sombre tint of gray, the boulder-clay assume^, as in the neighbor- hood of Wick and Thurso, the leaden color of the beds which it overlies; while over the Coal Measures of the south of Scotland, as in East and West Lothian, and around Edinburgh, it is of a bluish-black tint, exactly the color which might be premised, on the polishing the- ory, from the large mixture of shale-beds, coal-seams, and trap-rocks, which occurs amid the prevailing light-hued sandstones of the deposits beneath. Of course, this con- dition of resemblance in average color between the rocks and the boulder-clays of a district is but of general, not invariable occurrence, the boulder-clay is not invariably the dressings of the rocks beneath. We may occasionally find the trail of the rubbings of one tract overlying, in an easterly direction, the deposits of a different one ; just as we would find the rubbings of variously-colored pieces of pavement laid down to form a floor, and then polished, square by square, where they lay, encroaching, the debris of one square on the limits of another, in the direction of the outward stroke of the polisher. But while we thus find all the conditions of a raft- formed deposit in or associated with the boulder-clay, such as grooved and furrowed rocks beneath, scratched and polished stones lined longitudinally inclosed in it, accompanied, in not a few instances, by rounded frag- ments of shells, and a general conformity in its color to that of the rocks on which it rests, where in nature shall we find the analogues of the producing rails thein- selvs? A native of Newfoundland, who season after LECTURES ON GEOLOGY. 75 season had seen the Arctic icebergs grating heavily along the coasts of the island, would experience little difficulty in solving the riddle. For rafts of wood we have but to substitute rafts of ice, a submerged land covered by many fathoms of water, for the shallows of the river of my illus- tration, and some powerful ocean current, such as the gulf or arctic stream, for the river itself, and we at once arrive at a consistent theory of the boulder-clay and its origin. Nor must we deem it a thing improbable, that a country like Scotland, which lies between the fifty-fifth and the fifty-ninth degree of north latitude, should be visited every year by icebergs. Newfoundland lies from five to eight degrees to the south of Scotland, and yet its north- ern shores are included in that vast cake of ice which, when winter sets fairly in, is found to stretch continu- ously, though in a winding line, over the surface of the ocean, from Nova Zembla in the Old World, to Labrador in the New ; and the drift ice-floes in spring, borne south- wards on the Arctic current, brush every season over its southern shores, or ground by hundreds upon its great bank ; nor do they finally disappear until they reach the fortieth, and, in at least one recorded instance, the thirty- sixth, degree of north latitude. I need scarce remind you that the temperatm-e of a country depends on other causes than its distance from the equator or the pole. The iso- thermal line, or line of mean temperature, of the capital of Iceland, Reikiavik, in latitude 64, is nearly as high as that of St. John's, the capital of Newfoundland, in lati- tude 47 ; and old York, in the fifty-fourth degree of north latitude, enjoys as much average warmth throughout the year as New York, in the fortyfirst degree. Now, the causes which give to countries in the same latitudes climates so strangely different are known not to be per- 76 LEG-TURKS ON GEOLOGY. manent causes: temperature is found to depend on the disposition of land and sea, and the position, not of the geographical pole, which is single and centrical in each hemisphere, but of the pole of greatest cold, which, in at least the northern hemisphere, is double, and not centri- cal, Asia having one, and America another ; and if, as is generally held, there be a correspondence amounting almost to identity between the poles of greatest cold and the magnetic poles, then these poles are not fixed, but oscillating. Nor are we left to infer on merely general grounds that the climate of our country may have been at one time greatly more severe than it is now. There is also zoological evidence that it was greatly more severe. It is a curious and significant fact, that the group of shells found in the boulder-clay, resting over the scratched and grooved rocks, and accompanying the scratched and pol- ished pebbles, is essentially a boreal or semi-arctic group. This little shell from the boulder-clay of Caithness the Trophon scalariformis or Fusus scalariformis, which, from its small size, seems to have escaped the fate that crushed its larger contemporaries into fragments is not now found living on our coasts, though it still exists in considerable abundance in the seas of Greenland ; and sev- eral of its neighbors in the clay, such as Tellina proxima and Astarte Borealis, are of the same northern character. Nay, in cases in which the shells of the boulder-clay still live in our seas, we find those of a northern character, such as the Cyprina Islandica, that, though not rare on the shores of Scotland, is vastly more abundant on those of Iceland, occurring, not in the present British, but in the present Icelandic proportions. The Cyprina Islandica is one of the most common shells of the clay, and, as its name testifies, one of the most common shells of Iceland ; LECTURES ON GEOLOGY. 77 but it is by no means one of the most common shells at the present time of our Scottish coasts. The shells of the boulder-clay correspond in the group, not to the present shells of Scotland, but to the present shells of Iceland and the Northern Cape. Further, we are not left merely to infer that icebergs could or might have grooved and worn down the rocks of the country : we learn from Sir Charles Lyell unques- tionably a competent observer that he caught icebergs almost in the very fact of grooving and wearing down similar rocks. In his first work of " Travels through the United States," he describes a visit which he paid to the coast of Nova Scotia, near Cape Blomidon : " As I was strolling along the beach," he says, " at the base of a line of basaltic cliffs, which rise over ledges of soft sandstone, I stopped short at the sight of an unexpected phenom- enon. The solitary inhabitant of a desert island could scarcely have been more startled by a human footprint in the sand than I was on beholding some recent furrows on a ledge of sandstone under my feet, the exact counterpart of those grooves of ancient date which I have so often attributed to glacial action On a recently formed ledge I saw several straight furrows half an inch broad, some of them very nearly parallel, others slightly diverg- ent ; and, after walking about a quarter of a mile, I found another set of similar furrows, having the same general direction within about five degrees ; and I made up my mind that, if these grooves could not be referred to the modern instrumentality of ice, it would throw no small doubt on the glacial hypothesis. When I asked my guide, a peasant of the neighborhood, whether he had ever seen much ice on the spot where we stood, the heat was so ex- cessive (for we were in the latitude of the south of Franc?, 7* 78 LECTURES ON GEOLOGY. 45 degrees north) that I seemed to be putting a strange question. He replied, that in the preceding winter [that of 1841J he had seen the ice, in spite of the tide, which ran at the rate of ten miles an hour, extending in one un- interrupted mass from the shore where we stood, to the opposite coast of Parrsborough, and that the rce- blocks, heaped on each other and frozen together, or packed at the foot of Cape Blornidon, were often fifteen feet thick, and were pushed along, when the tide rose, over the sand- stone ledges. He also stated that fragments of the black stone which fell from the summit of the cliff a pile of which lay at its base were often frozen into the ice, and moved along with it. And I have no doubt that the hard- ness of these gravers, firmly fixed in masses of ice, which, though only fifteen feet thick, are often of considerable horizontal extent, has furnished sufficient pressure and me- chanical power to groove the ledges of soft sandstone." Thus far Sir Charles. The boulder-clay is found in Scotland from deep beneath the sea-level, where it forms the anchoring ground of some of our finest harbors, to the height of from six to nine hundred feet along our hill- sides. The travelled boulders to which it owes its name have been found as high as .fourteen hundred feet. Up to the highest of these heights icebergs at one time operated upon our Scottish rocks. Scotland, therefore, must in that icy age have been submerged to the highest of these heights. It must have existed as three groups of islands, the Cheviot, or southern group ; the Grampian, or middle group ; and the Ben Weavis, or northern group. Let me next advert to a peculiarity in the direction of the icebergs which went careering at this period over the submerged land. As shown by the lines and furrows which they have graven upon the rocks, their general LECTURES ON GEOLOGY. 79 course, with a few occasional divergences, effects appa- rently, of the line of the greater valleys, was from west to east. It is further a fact, exactly correspondent in the evidence which it bears, that the trap eminences of the country eminences of hard rock rising amid districts of soft sandstone, or still softer shale have generally at- tached to their eastern sides sloping tali of the yielding strata out of which they rise, and which have been washed away from all their other sides. Every larger stone in a water-course, after the torrent fed by a thunder-shower has just subsided, shows, on the same principle, its trail of sand and shingle piled up behind it sand and shingle which kept it from being swept awfly ; and the simple ef- fect, when it occurs on the large scale, is known to the geologist as the phenomenon of "Crag and tail." The rock upon which Edinburgh Castle stands, existing as the " crag? and the sloping ridge which extends from the cas- tle's outer moat to Holyrood, existing as the tail, may be cited as a familiar instance. We find the same phenom- enon repeated in the Calton Hill, and in various other eminences in the neighborhood ; as also in the Castle Hill of Stirling. And in all these, and in many other cases, the tail which the crag protected is turned towards the east, indicating that the current which in the lapse of ages scooped out the valleys at the sides of the protecting crags, and in many instances formed, by its eddies, hollows in advance of them, just as we find hollows in advance of the larger stones of the water-course of my illustration, was a current which flowed from the west. The testi- mony of the ice-grooved rocks, and of the eminences composed of crag and tail, bear, we see, in this same line. Now, this westerly direction of the current seems to be exactly that which, reasoning from the permanent phe- 80 LECTURES ON GEOLOGY. nomena of nature, might be premised. There must have been trade winds in every period of the world's history, in which the earth revolved from west to east on its axis; and with trade winds the accompanying drift current. And, of consequence, ever since the existence of a great western continent, stretching far from south to north, there must have been also a gulf stream. The waters 'heaped up against the coasts of this western continent at the equator by the drift current ever flowing westwards, must have been always, as now, returning eastwards in the temperate zone, to preserve the general level of the ocean's surface. Ever, too, since winter took its place among the seasons, there must have been an arctic current. The ice and snows of the higher latitudes, that accumu- lated during the winter, must have again melted in spring, and early summer; and a current must in consequence have set in as the seasons of these came on, just as we now see such a current setting in, in these seasons, in both hemispheres, which bears the ice of the antarctic circle far towards the north, and the ice of the arctic circle far to- wards the south. The point at which, in the existing state of things, the gulf stream and the arctic current come in contact is that occupied by the great bank of Newfound- land ; and by some the very existence of the bank has been attributed to their junction, and to the vast accumu- lation of gravel and stone cast down year after year from the drift ice to the bottom, where these two great tides meet and jostle. Be this as it may, the number of boul- ders and the quantity of pebbles and gravel strewed over the bottom of the western portions of the Atlantic, in the line of the arctic current, from the confines of Baffin's Bay up to the forty-fifth degree of north latitude, must be alto- gether enormous. Captain Scoresby counter! no fewer LECTURES ON GEOLOGT. 81 than five hundred icebergs setting out on their southern voyage on the arctic current at one time. And wherever there are shallows on which these vast masses catch the bottom, or grate over it, shallows of from thirty to a hundred fathoms water, we may safely premise that at the present time there is a boulder-clay in the course of formation, with a scratched and polished surface of rock lying beneath it, and containing numerous pebbles and boulders striated longitudinally. That the point where the gulf and arctic currents come in contact should now lie sc far to the west, is a consequence of the present dis- position of the arctic and western continents, perhaps also of the present position of the magnetic pole. A dif- ferent arrangement and position would give a different point of meeting ; and it is as little improbable that they should have met in the remote past some two or three hundred miles to the west of what is now Scotland, as that in the existing period they should meet some two or three hundred miles to the east of what is now Newfoundland. The northern current would be deflected by the more pow- erful gulf stream into an easterly course, and would go sweeping over the submerged land in the direction indi- cated by the grooves and scratches, bearing with it every spring its many thousand gigantic icebergs, and its fields of sheet-ice many hundred square miles in extent. And these, armed beneath with great pebbles and boulders, or finding many such resting at the bottom, by grinding heavily along the buried surface, like the rafts of my illustration along the bed of the river, would gradually tvear down the upper strata of the softer formations, leav- ing the clay which they had thus formed to be deposited over, and a little to the east of, the rocks that had pro- duced it. It is further in accordance with this theory, that 82 LECTURES OX UEOLOGY. in Scotland generally, the deeper deposits of the boulder- clay occur on the eastern line of coast. The cutler, in whetting a tool with water on a flat Turkey stone, drives the gray, milky dressings detached by the friction of the steel from the solid mass, to the end of the stone farthest from himself and there they accumulate thick in the direc- tion of the stroke. And so it is here. The rubbings of the great Scotch whetstone, acted upon by the innumer- able gravers and chisels whetted upon it, and held down or steadied by the icebergs, have been carried in the east- erly direction of the stroke, and deposited at the further, that is to say, the eastern, end of the stone. But fearing I have already too much trespassed on your time and patience, I shall leave half told for the present the story of the Pleistocene period in Scotland. If, in- stead of presenting it to you as ? piece of clear, condensed narrative, I have led you darkly to grope your way through it by a series of fatiguing inductions, you will, I trust, sustain my apology, when I remind you that this dreary ice-epoch in the history of our country, still forms as debateable a terra incognita to the geologist as the dreary ice-tracts which surround the pole do to the ge- ographer. We have been threading our twilight way through a difficult North- West Passage ; and if our prog- ress has been in some degree one of weariness and fatigue, we must remember that without weariness and fatigue no voyager ever yet explored " The ice-locked secrets of that hoary deep Where fettered streams and frozen continents Lie dark and wild, beat with perpetual storm Of whirlwind and dire hail." "We might expect," says Professor Sedgwick, "that as we come close upon living nature, the characters of our old LECTURES ON GEOLOGY. 88 records would grow legible and clear. But just where we begin to enter on the history of the physical changes going on before our eyes, and in which we ourselves bear a part, our chronicle seems to fail us: a leaf has been torn out from Nature's book, and the succession of events is almost hidden from our eyes." Now, it is to this age of the drift- gravels and the boulder-clay that the accomplished Pro- fessor here refers, as represented in the geologic record by a torn page ; and though we may be disposed to view it rather as a darkened one, much soiled, but certainly not awaiiting, we must be content to bestow on its dim, half- obliterated characters, more time and care than suffice for the perusal of whole chapters in the earlier books of our history. And so, casting myself on your forbearance, I shall take up the unfinished story of the Pleistocene period in Scotland in my next address LECTURE SECOND. Problem first propounded to the Author in a Quarry The Quarry's Two Depos- its, Old Red Sandstone and Boulder-Clay The Boulder-Clay formed while the Laud was subsiding The Groorings and Polishings of the Rocks in the Lower Parts of the Country evidences of the fact Sir Charles Lyell's Observations on the Canadian Lake District Close of the Boulder-Clay Record in Scotland Its Continuance in England into the Pliocene Ages The Trees and Animals of the Pre-Glacial Periods Elephants' Tusks found in Scotland and England regarded as the Remains of Giants Legends concerning them Marine De- posits beneath the Pre-Glacial Forests of England Objections of Theologians to the Geological Theory of the Antiquity of the Earth and of the Human Race considered Extent of the Glacial Period in Scotland Evidences of Glacial Action in Glencoe, Gareloch, and the Highlands of Sutherland Sce- nery of Scotland owes its Characteristics to Glacial Action The Period of Elevation which succeeded the Period of Subsidence Its Indications in Raised Beaches and Subsoils How the Subsoils and Brick Clays were formed Their Economic Importance Boulder-Stones interesting Features in the Landscape Their prevalence in Scotland The more remarkable Ice-trav- elled Boulders described Anecdotes of the " Travelled Stone of Petty " and the Standing Stone of Torribal Elevation of the Land during the Post-Ter- tiary Period which succeeded the Period of the Boulder-Clay The Alpine Plants of Scotland the Vegetable Aborigines of the Country Panoramic View of the Pleistocene and Post-Tertiary Periods Modern Science not adverse to the Development of the Imaginative Faculty. I REMEMBER, as distinctly as if I had quitted it but yes- terday, the quarry in which, some two-and-thirty years ago, I made my first acquaintance with a life of toil and restraint, and at the same time first broke ground as a geologist. It formed a section about thirty feet in height by eighty or a hundred in length, in the front of a furze- covered bank, a portion of the old coast line ; and pre- sented an under bar of a deep-red sandstone arranged in nearly horizontal strata, and an upper bar of a pale-red LECTURES ON GEOLOGY. 85 clay roughened by projecting pebbles and boulders. Both deposits at the time were almost equally unknown to the geologist. The deep-red sandstone beneath formed a por- tion of that ancient Old Red system which represents, as is now known, the second great period of vertebrate exist- ence on our planet, and which has proved to the palaeon- tologist so fertile a field of wonders : the pale clay above was a deposit of the boulder-clay, resting on a grooved and furrowed surface of rock, and containing in abundance its scratched and polished pebbles. Old Red Sandstone and boulder-clay! a broad bar of each; such was the compound problem propounded to me by the Fate that dropped me in a quarry ; and I gave to both the patient study of years. But the older deposit soon became frank and communicative, and yielded up its organisms in abun- dance, which furnished me with many a curious little anec- dote of their habits when living, and of the changes which had passed over them when dead ; and I was enabled, with little assistance from brother geologists, to give a his- tory of the system to the world more than ten years ago. The boulder-clay, on the contrary, remained for years in- vincibly silent and sullen. I remember a time when, after passing a day under its barren scaurs, or hid in its precip- itous ravines, I used to feel in the evening as if I had been travelling under the cloud of night, and had seen nothing. It was a morose and taciturn companion, and had no spec- ulation in it. I might stand in front of its curved preci- pices, red, yellow, or gray (according to the prevailing color of the rocks on which it rested), and might mark their water-rolled boulders of all kinds and sizes sticking ^ut in bold relief from the surface, like the protuberances that roughen the rustic basements of the architect ; but I had no " Open Sesame" to form vistas through them into ib LECTURES ON GEOLOGY. die recesses of the past. And even now, when I have, I think, begun to understand the boulder-clay a little, and it has become sociable enough to indulge me with occa- sional glimpses of its early history in the old glacial period, glimpses of a half-submerged land, and an iceberg-mot- tled sea, turbid with the comminuted debris of the rocks below, you will see how very much I have had to borrow from the labors of others, and that, in worming my way into its secret, there are obscure recesses within its pre- cincts into which I have failed to penetrate. Let us now, however, resume its half-told story. There are appearances which lead us to conclude, that during the formation and deposition of the boulder-clay, what is now Scotland was undergoing a gradual subsid- ence, gradually foundering amid the waves, if I may so speak, like a slowly-sinking vessel, and presenting, as cen- tury succeeded century, hills of lower and yet lower alti- tude, and an ever lessening area. I was gratified to find, that when reasoning out the matter for myself, and arriv- ing at this conclusion from the examination of one special set of data, Mr. Charles Darwin was arriving at the same conclusion from the consideration of a second and entirely different set ; and Sir Charles Lyell from whom, on the publication of my views in the "Witness" newspaper some four years since, I received a kind and interesting note on the subject had also arrived at the same conclusion North America being the scene of his observations from the consideration of yet a third and equally distinct set. And in the " Geological Journal " for the present year, I find Mr. Joshua Trimmer and Mr. Austin arriving, from evidence equally independent, at a similar finding. We " have all come to infer, in short, that previous to the Drift period the land had stood at a comparatively high level, LECTURES ON GEOLOGY. 87 perhaps higher than it does now ; that ages of depression canie on, during which the land sank many hundred feet, and the sea rose high on the hill-sides ; and that during these ages of depression the boulder-clay was formed. Let me state briefly some of the considerations on which we found. The boulder-clay, I thus reasoned with myself, is gener- ally found to overlie more deeply the lower parts of the country than those higher parts which approach its upper limit ; and yet the rocks on which it rests, in some local- ities to the depth of a hundred feet at even the level of the sea, bear as decidedly their groovings and polishings as those on which, eight hundred feet over the sea-level, it reposes to but the depth of a yard or two. Now, had a rising land been subjected piecemeal to the grinding action of the icebergs, this would not have been the case. The higher rocks first subjected to their action would of course bear the groovings and furrowings ; but the argil- laceous dressings detached from them in the process, mixed with the stones and pebbles which the ice had brought along with it, would necessarily come to be deposited in the form of boulder-clay on the lower rocks ; and ere these lower rocks could be brought, by the elevation of the land, within reach of the grinding action of the icebergs, they would be so completely covered up and shielded by the deposit, that the bergs would fail to come in contact with them. They would go sweeping, not over the rocks themselves, but over the clay by which the rocks had been covered up; and so we may safely infer that, had the boulder-clay been formed during an elevating period, the lower rocks, where thickly covered by the clay, would not be scratched and grooved as we now find them, or, where scratched and grooved, 'would not be thickly covered by 88 LECTURES ON GEOLOGY. the clay. The existing phenomena, deep grooves and polished stria?, on rocks overlaid at the present sea-level to a great depth by the boulder-clay, demand for their production the reverse condition of a sinking land, in which the lower rocks are first subjected to the action of the icebergs, and the higher rocks after them. The quar- rier, when he has to operate on some stratum of rock on a hill-side, has to commence his labors below, and to throw the rubbish which he forms behind him, leaving an open face in front ; for, were he to reverse the process, and com- mence above, the accumulating debris, ever seeking down- wards, would at length so choke up the working as to arrest his labors. And such, we infer from the work done, must have been the course of operations imposed by the conditions of a sinking land on the icebergs of the glacial period : they began their special course of action at the hill-foot, and operated upon its surface upwards as the sea arose. Again, Mr. Darwin's reasonings were mainly founded on the significant fact, that in numerous instances travelled boulders of the ice period may be found on levels considerably higher than those of the rocks from which they were originally torn. And though cases of transport from a lower to a higher level could and would take place during a period of subsidence, when the sea was rising or the land sinking, it is impossible that it could have taken place during an elevating period, when the sea was sink- ing or the land rising. 1 A flowing sea, to use a simple illustration, frequently carries shells, pebbles, and sea-weed from the level of ebb to the level of flood; it brings them from a low to a high level : whereas an ebbing sea 1 See Mr. Trimmer's last paper on Boulder-Clays, " Journal of the Geo- lo-iru] Society," May, 18-38, p. 171. W. S. LECTURES ON GEOLOGY. 89 can but reverse the process, by bringing them from a high level to a low. For the facts and reasonings of Sir Charles Lyell on the subject I must refer you as they are incapable of being abridged without being injured to that portion of his first work of Travels in America which treats of the Cana- dian Lake District. But the following are his conclusions : "First? he says, "the country acquired its present geo- graphical configuration, so far as relates to the older rocks, under the joint influence of elevating and denuding oper- ations. Secondly, a gradual submergence then took place, bringing down each part of the land successively to the level of the waters, and then to a moderate depth below them. Large islands and bergs of floating ice came from the north, which, as they grounded on the coast and on shoals, pushed along all loose materials of sand and peb- bles, broke ofi" all angular and projecting points of rock, and, when fragments of hard stone were frozen into their lower surfaces, scooped out grooves in the subjacent solid strata. Thirdly, after the surface of the rocks had been smoothed and grated upon by the passage of innumerable icebergs, the clay, gravel, and sand of the Drift were de- posited; and occasionally fragments of rock, both large and small, which had been frozen into glaciers, or taken up by coast-ice, were dropped here and there at random over the bottom of the ocean, wherever they happened to be detached from the melting ice. Finally, the period of reelevation arrived, or of that intermittent upward move- ment in which the old coast lines were excavated and the ancient sand bars or osars laid down." Such are the con- clusions at which Sir Charles Lyell arrived a few years since respecting the Canadian Lake District ; and he states, in the note to which I have referred, that he has 8* 00 LECTURES ON GEOLOtiV. ever since been applying them to Scotland. Our country, during the chill and dreary period of the boulder-clay, seems to have been settling down into the waves, like the vessel of some hapless Arctic explorer struck by the ice in middle ocean, and sinking by inches amid a wild scene of wintry desolation. There are a few detached localities in Scotland where the remains of beds of stratified sand and gravel have been detected underlying the boulder-clay ; and in some of these in the valley of the Clyde, Mr. Smith, of Jordan- hill, found, on a late occasion, shells of the same semi- arctic character as those which occur in the clay itself. And with these stratified beds the record in Scotland closes; whereas in England we find it carried interest- ingly onward from the Pleistocene period, first into the newer, and then into the older, Pliocene ages. I stated incidentally in my former address, that some of the mosses of the sister kingdom, unlike those of our own country, are older than the Drift period ; and, from the existence of these under the Drift gravels and brown clay, it has been inferred by Mr. Trimmer, that as the trees which enter into their composition grew upon the surface of what is now England, where they now lie, previous to the period of the boulder-clay, and as the boulder-clay is, as shown by its remains, decidedly marine, it must have been depos- ited during a period of depression, when what had been a forest-bearing surface was lowered beneath the level of the sea. None of the trees of these ancient pre-glacial forests seem to be of extinct species; the birch and Scotch fir are among their commonest forms, especially the fir. I find it stated, however, as a curious fact, that along with these, the Abies E/xcelsa, or Norwegian spruce-pine, is found to occur, a tree which, though introduced by man LECTURES ON GEOLOGY. 91 into our country, and now not very rare in our woods, has not been of indigenous growth in any British forest since the times of the boulder-clay. Though the species con- tinued to live in Norway, it became extinct in Britain ; and it has been suggested, that as it was during the Drift period that it disappeared, it may have owed its extirpa- tion to the depression of the land, while its contemporaries the birch and fir were preserved on our northern heights. When this Norwegian pine flourished in Britain, the island was inhabited by a group of quadrupeds now never seen associated, save perhaps in a menagerie. Mixed with the remains of animals still native to our country, such as the otter, the badger, and the red deer, there have been found skeletons of the Lagomy, or tailless hare, now an inhab- itant of the cold heights of Siberia, and horns of the rein- deer, a species now restricted in Europe to northern Scandinavia, and those inhospitable tracts of western Russia that border on the Arctic Sea. And with these boreal forms there were associated, as shown by their bones and tusks, the elephant, the rhinoceros, and the hippopota- mus, all, however, of extinct species, and fitted for liv- ing under widely different climatal conditions from those essential to the well-being of their intertropical congeners. 1 Scotland, though it has proved much less rich than Eng- land in the remains of the early Pleistocene mammals, has furnished a few well-attested elephantine fossils. In the summer of 1821, in the course of cutting the Union Canal, there was found in the boulder-clay near Falkirk, on the Clifton Hall property, about twenty feet from the surface, 1 The true mammoth, with the tichorine rhinoceros and the mnsk buf- falo, are the leading types of the mammalian fauna of the Glacial Drift epoch. The remains of hippopotamus would be washed out of older beds. W. S. 92 LECTURES ON GEOLOGY. a large portion of the tusk of an elephant, three feet three inches in length, and thirteen inches in circumference ; and such was its state of keeping when first laid open, that it was sold to an ivory-turner by the laborers that found it, and was not rescued from his hands until a portion of it had been cut up for chessmen. Two other elephants' tusks were found early in 1817, at Kilmaurs, 1 in Ayrshire, on a property of the Earl of Eglinton, one of them so sorely decayed that it could not be removed ; but a portion of the other, with the rescued portion of the Falkirk tusk, may be seen in the Museum of our Edinburgh University, which also contains, I may here mention, the horn of a rhinoceros, found at the bottom of a morass in Forfarshire, but which, in all probability, as it stands alone among the organisms of our mosses, had been washed out of some previously formed deposit of the Drift period. Scotland seems to have furnished several other specimens of ele- phantine remains; but as they were brought to light in ages in which comparative anatomy was unknown, and men believed that the human race had been of vast strength and stature in the primeval ages, but were fast sinking into dwarfs, they were regarded as the remains of giants. Some of the legends to which the bones of these supposed giants served to give rise in England, occupy a place in the first chapter of the country's history, as told by the monkish chroniclers, and have their grotesque but widely-known memorials in Gog and Mngog, the wooden giants of Guildhall : our Scottish legends of the same class are less famous ; but to one of their number charged 1 At a later period (December 1829), similar elephantine tusks were found thirty-four feet beneath the surface, in boulder-clay overlying the quarry of Greenhill, also in Kilmaurs parish; and they may now be seen in the Hunterian Museum, Glasgow. LECTURES ON GEOLOGY. 93 with an argument in behalf of the temperance cause of which our friends the teetotalers have not yet availed themselves I may be permitted briefly to refer, in the words of one of our elder historians. " In Murray land," says the believing Hector Boece, " is the Kirke of Pette, quhare the bones of Litell Johne remainis in gret admira- tion of pepill. He hes bene fourtene feet of hicht, with squaire membres offering thairto. Six yeirs afore the coming of this work to licht (1520), we saw his henche bane, as meikle as the haill banes of ane manne ; for we schot our arme into the mouthe thairof ; be quhilk appeirs how strang and squaire pepill greu in cure regeoun afore thay were effeminat with lust and intemperance of mouthe." Under these pre-glacial forests of England there rests a marine deposit, rich in shells and quadrupedal remains, known as the Norwich or Mammaliferous Crag; and be- neath it, in turn, lie the Red and Coralline Crags, mem- bers of the Pliocene period. In the Mammaliferous Crag there appear a few extinct shells, blent with shells still common on our coasts. In the Red Crag the number of extinct species greatly increases, rising, it is now estimated, to thirty per cent, of the whole ; while in the Coralline Crag the increase is greater still, the extinct shells averag- ing about forty per cent. 1 In these deposits some of our best known molluscs appear in creation for the first time. The common edible oyster ( Ostrea edulis) occurs in the Coralline Crag, but in no older formation, and with it the great pecten (Pecten maximus), the horee mussel (Modi- ola vulgaris), and the common whelk (Buccinum unda- twri). Other equally well-known shells make their advent 1 The known species of shells in the Coralline Crag amount to three hundred and forty. Of these, seventy-three are living British species. See Woodward's " Manual," part iii. p. 421. W. S. 94 LECTURES ON GEOLOGY. at a still later period; the common mussel (Mytilus nln- lis), the common periwinkle (Littorina littoreci), and, in Britain at least, the dog-whelk (Purpura lapillus), first appear in the overlying Red Crag, and are not known in the older Coralline formation. By a certain very extended period, represented by the Coralline Crag, the edible oyster seems to be older than the edible mussel, and the common whelk than the common periwinkle ; and I call your spe- cial attention to the fact, as representative of a numerous class of geological facts that bear on certain questions of a semi-theological character, occasionally mooted in the religious periodicals of the day. There are few theolo- gians worthy of the name who now hold that the deduc- tions of the geologists regarding the earth's antiquity are at variance with the statements of Scripture respecting its first creation, and subsequent preparation for man. But some of them do seem to hold that the scheme of reconciliation, found sufficient when this fact of the earth's antiquity was almost the only one with which .we had to grapple, should be deemed sufficient still, when science, in its onward progress, has called on us to deal with this new fact of the very unequal antiquity of the plants and ani- mals still contemporary with man, and with the further fact, that not a few of them must have been living upon the earth thousands of years ere he himself was ushered upon it, facts of course wholly incompatible with any scheme of interpretation that would fix the date of their first appearance only a few natural days in advance of that of his own. We have no good reason to hold that the human species existed upon earth during the times of the boulder-clay: such a belief would conflict, as shown by the antiquity of the ancient and existing coast lines, with our received chronologies of the race. But long previous to LECTURES ON GEOLOGY. 95 these times, the Norwegian spruce pine and the Scotch fir were natives of the pre-glacial forests of our country ; at even an earlier period the common periwinkle and edible mussel lived in the seas of the Red Crag deposits ; and at a still earlier time, the great pecten, the whelk, and the oyster, in those of the Coralline Crag. We can now no more hold, as geologists, that the plants and animals of the existing creation eame into being only a few hours or a few days previous to man, than that the world itself came into being only six thousand years ago ; and we do think we have reason to complain of theologians who, ignorant of the facts with which we have to deal, and in no way solicitous to acquaint themselves with them, set themselves coolly to criticize our well-meant endeavors to reconcile the Scripture narrative of creation with the more recent findings of our science, and who pronounce them inadmissible, not because they do not effect the desired reconciliation, but simply because they are now to theol- ogy. They should remember that the difficulty also is new to theology; that enigmas cannot be solved until they are first propounded ; that if the riddle be in reality a new one, the answer to it must of necessity be new like- wise ; and as this special riddle has been submitted to the geologists when the theologians were unaware of its exist- ence, it must not be held a legitimate objection, that geolo- gists, who feel that they possess, as responsible men, a stake in the question, should be the first to attempt solving it. If, however, it be, as I suspect, with our facts, not with our schemes of reconciliation, that the quarrel in reality lies, if it be, in particular, with the special fact of the une- qual antiquity of the existing plants and animals, and the comparatively recent introduction of man, I would fain urge the objectors to examine ere they decide, and not 9S LECTURES ON GEOLOGY. r:ishly and in ignorance to commit themselves against truths which every day must render more palpable and clear, and which are destined long to outlive all cavil and opposition. With respect to the antiquity of our race, we have, as I have said, no good grounds to believe that man existed upon the earth during what in Britain, and that portion of the continent which lies under the same lines of lati- tude, were the times of the boulder-clay and Drift gravels. None of the human remains yet found seem more ancient than the historic period, in at least the older nations ; it is now held that the famous skeletons of Guadaloupe be- longed to men and women who must have lived since the discovery of America by Columbus; and if in other parts of the world there have been detected fragments of the human frame associated with those of the long extinct animals, there is always reason to conclude that they owe such proximity to that burying propensity to which I have already adverted, or to accidents resulting from it, and not to any imaginary circumstance of contemporarily of exist- ence. If man buries his dead in the Gault or the London Clay, human reniains will of course be found mingled with those of the Gault or the London Clay; but the evidence furnished by any such mixture will merely serve to show, not that the existences to which the remains belonged had lived in the same age, but simply that they had been deposited in the same formation. Nor can I attach much value to the supposed historic records of countries such as Kgypt, in which dynasties arc represented as having flour- ished thousands of years ere the era of Abraham. Tlu< chronicles of all nations have their fabulous introductory ] tort ions. No one now attaches any value to the record of the eighty kings that are said to have reigned in Scot- LECTURES ON GEOLOGY. 97 land between the times of Fergus the First and Constan- tino the Bold ; or to that portion of old English history which treats of the dynasty of Brutus the Parricide, or his wars with the giants. All the ancient histories have, as Buchanan tells us, in disposing of the English claims, their beginnings obscured by fable ; nor is it probable that the Egyptian history is an exception to all the others, or that its laboriously inscribed and painfully interpreted hieroglyphics were more exclusively devoted to the re- cording of real events than characters simpler of form and easier of perusal. If, as some contend, man has been a denizen of this world for some ten or twelve thousand years, what, I would ask, was he doing the first five or six thousand? It was held by Sir Isaac Newton, that the species must have been of recent introduction on eai-th, seeing that all the great human discoveries and inventions, such as letters, the principles of geometry and arithmetic, printing, and the mariner's compass, lie within the historic period. The mind of man could not, he inferred, have been very long at work, or, from its very constitution, it would have discovered and invented earlier ; and all his- tory and all archaeological research bear out the inference of the philosopher. The older civilized nations lie all around the original centre of the race in Western Asia ; nor do we find any trace of a great city older than Nine- veh, or of a great kingdom that preceded in its rise that of Egypt. The average life of great nations does not exceed twelve, or at most fifteen, hundred years ; and the first great nations were, we find, living within the memory of letters. Geology, too, scarce less certainly than Reve- lation itself, testifies that the last-born of creation was man, and that his appearance on earth is one of the most 9 98 LECTURES OX ^ which, even where the boulder-clay is shell-bearing, coifr" tains no shells. There are other localities in which a sin*-- ilar deposit also underlies the boulder-clay; and these deposits, upper and lower, are in all probability the debris of glaciers that existed in our country during the ice era, the lower deposit being the debris of glaciers that had existed previous to the glacial period of subsidence, and the upper that of glaciers which had existed posterior to it, and when the land was rising. The evidence is, I think, conclusive, that glaciers there were. I examined, during the autumn of last year, the famous Glencoe, and can now entertain no more doubt that a glacier once descended along the bottom of that deep and rugged valley, filling it up from side to side to the depth of from a hundred and fifty to two hundred feet, than that an actual glacier de- scends at the present day along the valley of the Aar or of the Grindelwald. The higher precipices of Glencoe are among the most rugged in the kingdom : we reach a cer- tain level; and, though no change takes place in the qual- ity of the rock, all becomes rounded and smooth, through the agency, evidently, of the vanished ice river, whose old line of surface we can still point out from the continuous mark on the sides of precipices, beneath which all is smooth, and above which all is rugged, and whose scratchings and groovings we can trace on the hard porphyry descending towards the Atlantic, even beyond where the sea occupies the bottom of the valley. The lines and grooves running in a reverse direction to those of the icebergs, for their course is towards the west, are distinctly discernible as far 100 LECTURES ON GEOLOGY. down as Ballachulish ferry. Similar marks of a great gla- cier in the valley of the Gareloch have been carefully traced and shrewdly interpreted by Mr. Charles M'Laren. But nowhere have I seen the evidence of glacial action more decided than in the Highlands of Sutherland, over which I travelled last August more than a hundred and fifty miles, for the purpose of observation. There is scarce a valley in that wild region, whether it open towards the northern or western Atlantic, or upon the German Ocean, that in this ungenial period was not cumbered, like the valleys of the upper Alps, by its burden of slowly descend- ing ice. Save where, in a few localities on the lower slopes of the hills, the true boulder-clay appears, almost all the subsoil of the country, whei'e it has a subsoil, is composed of a loose, unproductive glacial debris; almost every prominence on the mountain-sides is rounded by the long- protracted action of the ice; and in many instances the surfaces of the rocks bear the characteristic groovings and scratchings as distinctly as if it had performed its work upon them but yesterday. Let me, however, repeat the remark, that the iceberg and glacial theories, so far from being antagonistic, ought rather to be regarded as equally indispensable parts of one and the same theory, parts which, when separated, leave a vast amount of residual phenomena to puzzle and perplex, that we find fully ac- counted for by their conjunction. And why not conjoin them? The fact that more than four thousand square miles of the interior of Iceland are covered by glaciers, is in no degree invalidated by the kindred fact that its shores are visited every spring by hundreds of thousands of ice- bergs. The glnciers of Scotland have, like its icebergs, contrib- uted their distinctive quota to the scenery of the country. LECTURES ON GEOLOGY. 101 The smoothed and rounded prominences of the hills, bare and gray amid the scanty heath, and that often after a sud- den shower gleam bright to the sun, like the sides and bows of windward-beating vessels wet by the spray of a summer gale, form well-marked features in the landscapes of the north-western parts of Sutherland and Ross, espec- ially in the gneiss and quartz-rock districts. The lesser islets, too, of these tracts, whether they rise in some soli- tary lochan among the hills, or in some arm of the sea that deeply indents the coast, still bear the rounded form originally communicated by the ice, and in some instances remind the traveller of huge whales heaving their smooth backs over the brine. Further, we not unfrequently see the general outline of the mountains affected ; all their peaks and precipices curved backwards in the direction whence the glacier descended, and more angular and ab- rupt in the direction towards which it descended. But it is in those groups of miniature hills, composed of glacial debris, which so frequently throng the openings of our Highland valleys, and which Burns so graphically describes in a single line as " Hillocks dropt in Nature's careless haste," that perhaps the most pleasing remains of our ancient gla- ciers are to be found. They seem to be modified moraines, and usually affect regular forms, resembling in some in- stances the roofs of houses, and in some the bottoms of upturned ships; and, grouped thick together, and when umbrageous with the graceful birch, or waving from top to base with the light fronds of the lady-fern and the bracken, they often compose scenes of a soft and yet wild loveli- ness, from which the landscape gardener might be content to borrow, and which seem to have impressed in a very 9* 102 LECTURES ON GEOLOGY. early age the Celtic imagination. They constitute the fairy Tomhans of Highland mythology; and many a curi- ous legend still survives, to tell of benighted travellers who, on one certain night of the year, of ghostly celebrity, have seen open doors in their green sides, whence gleams of dazzling light fell on the thick foliage beyond, and have heard voices of merriment and music resounding from within ; or who, mayhap, incautiously entering, have lis- tened entranced to the song, or stood witnessing the dance, until, returning to the open air, they have found that in what seemed a brief half hour half a lifetime had passed away. There are few of the remoter valleys of the Highlands that have not their groups of fairy Tomhans, memorials of the age of ice. After the lapse of ages but who can declare their number? the period of subsidence represented by the boulder-clay came to a close, and a period of elevation succeeded. The land began to rise ; and there is consid- erable extent of superficial deposits in Scotland which we owe to this period of elevation. It is the main object of the ingenious work of Mr. Robert Chambers on Raised Beaches to show that there were pauses in the elevating process, during which the lines against which the waves beat were hollowed into rectilinear terraces, much broken, it is true, and widely separated in their parts, but that wonderfully correspond in height over extensive areas. It is of course to be expected, that the higher and more ancient the beach or terrace, the more must it be worn down by the action of the elements, especially by the descent of water-courses; and as the supposed beaches intermediate between the strongly-marked ancient coast line which I have already described at such length, and certain upper lines traceable in the moorland districts of LECTURES ON GEOLOGY. 103 the country, occur in an agricultural region, the obliterat- ing wear of the plough has been added to that of the cli- mate. After, however, all fair allowances have been made, there remain great difficulties in the way. I have been puzzled, for instance, by the fact that Scotland presents us with but two lines of water-worn caves, that of the present coast line, and that of the old line immediately above it. Mr. Chambers enumerates no fewer than fifteen coast lines intermediate between the old coast line and a coast line about three hundred feet over it ; and in the range of granitic rocks which skirt on both sides the en- trance of the Cromarty Frith, there are precipices fully a hundred yards in height, and broadly exposed to the stormy north-east, whose bases bear their double lines of deeply-hollowed caverns. But they exhibit no third, or fourth, or fifth line of caves. Equally impressible through- out their entire extent of front, and with their inclosed masses of chloritic schist and their lines of fault as thickly set in their brows as in their bases, they yet present no upper stories of caves. Had the sea stood at the fifteen intermediate lines for periods at all equal in duration to those in which it has stood at the ancient or existing coast line, the taller precipices of the Cromarty Sutors would present their seventeen stories of excavations ; and exca- vations in hard granitic gneiss that varied from twenty to a hundred feet in depth would form marks at least as in- delible as parallel roads on the mountain sides, or mounds of gravel and debris overtopping inland plains, or rising over the course of rivers. The want of lines of caves higher than those of the ancient coast line would seem to indicate, that though the sea may have remained long enough at the various upper levels to leave its mark on soft, impressible materials, it did not remain long enough to excavate into caverns the solid rocks. 104 LECTURES ON GEOLOGY. But though the rise of the land may have been compar- atively rapid, there was quite time enough during the term of upheaval for a series of processes that have given con- siderable variety to the subsoils of our country. Had the land been elevated at one stride, almost the only subsoil of what we recognize as the agricultural region of Scot- land would have been the boulder-clay, here and there curiously inlaid with irregular patches of sand and gravel, which occur occasionally throughout its entire thickness, and which were probably deposited in the forming mass by icebergs, laden at the bottom with the sand and stones of some sea-beach, on which they had lain frozen until floated off, with their burdens, by the tide. But there elapsed time enough, during the upheaval of the land, to bring its boulder-clay deposits piecemeal under the action of the tides and waves; and hence, apparently, the origin of not a few of our lighter subsoils. Wherever the waves act at the present time upon a front of clay, we see a separation of its parts taking place. Its finer argillaceous particles are floated off to sea, to be deposited in the outer depths ; its arenaceous particles settle into sand-beds a little adown the beach ; its pebbles and boulders form a surface stratum of stones and gravel, extending from the base of the scaur to where the surf breaks at the half-tide line. We may see a similar process of separation going on in ravines of the boulder-clay swept by a streamlet. After every shower the stream comes down brown and turbid with the more argillaceous portions of the deposit ; accumulations of sand are swept to the gorge of the ravine, or cast down in ripple-marked patches in its deeper pools ; beds of pebbles and gravel are heaped up in every inflection of its banks ; and boulders are laid bare along its sides. Now, a separa- tion by a sort of washing process of an analogous charac- LECTURES ON GEOLOGY. 105 ter seems to have taken place in the materials of the more exposed portions of the boulder-clay, during the emergence of the land ; and hence, apparently, those extensive beds of sand and gravel which in so many parts of the kingdom exist in relation to the clay as a superior or upper subsoil ; hence, too, occasional beds of a purer clay than that be- neath, divested of a considerable portion of its arenaceous components, and of almost all its pebbles and boulders. This washed clay a re-formation of the boulder deposit cast down mostly in insulated beds in quiet localities, where the absence of currents suffered the purer particles, held in suspension by the water, to settle, forms, in Scot- land at least, with, of course, the exception of the ancient fire-clays of the Coal Measures, the true brick and tile clays of the agriculturist and architect. There are exten- sive beds of this washed clay within a short distance of Edinburgh ; and you might find it no uninteresting em- ployment to compare them, in a leisure hour, with the very dissimilar boulder-clays over which they rest. Unlike the latter, they are finely laminated : in the brick beds of Portobello I have seen thin streaks of coal-dust, and occa- sionally of sand, occurring between the layers ; but it is rare indeed to find in them a single pebble. They are the washings, in all likelihood, of those boulder-clays which rise high on the northern flanks of the Pentlands, and occur in the long, flat valley along which the Edinburgh and Glasgow Railway runs, washings detached by the waves when the land was rising, and which, carried towards the east by the westward current, were quietly deposited in the lee of Arthur Seat and the neighboring eminences, at that time a small group of islands. The only shells I ever detected in the brick-clay of Scotland occurred in a deposit in the neighborhood of St. Andrew's, of appar- 106 LECTURES ON GEOLOGY. ently the same age as the beds at Portobello. 1 They were in a bad state of keeping ; but I succeeded in identifying one of the number as a deep-sea Balanus, still thrown ashore in considerable quantity among the rocks to the south of St. Andrew's. In this St. Andrew's deposit, too, I found the most modern nodules I have yet seen in Scot- land, for they had evidently been hardened into stone dur- ing the recent period; but, though I laid them open by scores, I failed to detect in them anything organic. Sim- ilar nodules of the Drift period, not unfrequent in Canada and the United States, are remarkable for occasionally containing the only ichthyolite found by Agassiz among seventeen hundred species, which still continues to live, and that can be exhibited, in consequence, in duplicate specimens, the one fit for the table in the character of a palatable viand, the other for the shelves of a geological museum in the character of a curious ichthyolite. It is the MaJlotus villosus, or Capelan (for such is its market- name), a little fish of the arctic and semi-arctic seas. " The Mallotus is abundant," says Mr. James Wilson, in his ad- mirable " Treatise on Fishes," " in the arctic seas, where it is taken in immense profusion when approaching the coasts to spawn, and is used as the principal bait for cod. A few are cured and brought to this country in barrels, where they are sold, and used as a relish by the curious in wines." Let me next call your attention to the importance, in an economic point of view, of the great geologic events which gave to our country its subsoils, more especially the boul- der-clay. This deposit varies in value, according to the nature of the rocks out of which it was formed ; but it is, even where least fertile, a better subsoil than the rock 1 See Note at the end of the Lectures. LECTURES ON GEOLOGY. 107 itself would have been ; and in many a district it furnishes our heaviest wheat soils. To the sand and gravel formed out of it, and spread partially over it, we owe a class of soils generally light, but kindly ; and the brick clays are not only of considerable value in themselves, but of such excellence as a subsoil, that the land which overlies them in the neighborhood of Edinburgh still lets at from four to five pounds per acre. I suspect that, in order to be fully able to estimate the value of a subsoil, one would need to remove to those rocky lands of the south that seeni doomed to hopeless barrenness for want of one. It is but a tedious process through which the minute lichen or dwarfish moss, settling on a surface of naked stone, forms, in the course of ages, a soil for plants of greater bulk and a higher order ; and had Scotland been left to the exclusive operation of this slow agent, it would be still a rocky desert, with perhaps here and there a strip of allu- vial meadow by the side of a stream, and here and there an insulated patch of mossy soil among the hollows of the crags ; but, though it might possess its few gardens for the spade, it would have no fields for the plough. We owe our arable land to that geologic agent which, grinding down, as in a mill, the upper layers of the surface rocks of the kingdom, and then spreading over the eroded strata their own debris, formed the general basis in which the first vegetation took root, and in the course of years com- posed the vegetable mould. A foundering land under a severe sky, beaten by tempests and lashed by tides, with glaciers half choking up its cheerless valleys, and with countless icebergs brushing its coasts and grating over its shallows, would have seemed a melancholy and hopeless object to human eye, had there been human eyes to look upon it at the time ; and yet such seem to have been the 108 LECTURES ON GEOLOGY. circumstances in which our country was placed by Him who, to "perform his wonders," " Plants his footsteps in the sea, And rides upon the storm," in order that at the appointed period it might, according to the poet, be a land " Made blithe by plough and harrow." From the boulder-clay there is a natural transition to the boulders themselves, from which the deposit derives its name. These remarkable travelled stones seem, from the old traditions connected with some of them, to have awak- ened attention and excited wonder at an early period, long ' ieology was known as a science; nor are they without their share of picturesqueness in certain situations. You will perhaps remember how frequently, and with what variety of aspect, Bewick, the greatest of wood engravers, used to introduce them into the backgrounds of his vig- nettes. " A rural scene is never perfect," says Shenstone, a poet of no very large calibre, but the greatest of landscape gardeners, " without the addition of some kind of building : I have, however, known," he adds, " a scaur of rock in great measure supplying the deficiency." And the justice of the poet's canon may be often seen exemplified in those more recluse districts of the country which border on the Highlands, and where a huge rock-like boulder, roughened by mosses and lichens, may be seen giving animation and cheerfulness to the wild solitude of a deep forest-glade, or to some bosky inflection of bank waving with birch and ha/.d on the side of some lonely tarn or haunted streamlet. r'.\cn on a dark, sterile moor, where the pale lichen springs LECTURES ON GEOLOGY. 109 up among the stunted heath, and the hairy club-moss goes creeping among the stones, some vast boulder, rising gray amid the waste, gives to the fatigued eye a reposing point, on which it can rest for a time, and then let itself out on the. expanse around. Boulder-stones are stil! very abun- dant in Scotland, though for the last century they have been gradually disappearing from the more cultivated tracts where there were fences or farm steadings to be built, or where they obstructed the course of the plough. We find them occurring in every conceivable situation : high on hill-sides, where the shepherd crouches beside them for shelter in a shower ; deep in the open sea, where they entangle the nets of the fisherman on his fishing banks ; on inland moors, where in some remote age they were labori- ously rolled together to form the Druidical circle or Pict's House ; or on the margin of the coast, where they had been piled over one another at a later time, as protecting bul- warks against the waves. They are no longer to be seen in this neighborhood in what we may term the agricultural region; but they still occur in great numbers atong the const, within the belt that intervenes between high and low water, and on an upper moorland zone over which the plough has not yet passed. Mr. Charles M'Laren describes, in his admirable little work on " The Geology of Fife and the Lothians," a boulder of mica schist weighing from eight to ten tons, which rests, among many others, on one of the Pentland Hills, and which derives an interest from the fact that, as shown by the quality of the rock, the nearest point from which it could have come is at least fifty miles away. A well-known greenstone boulder of still larger size may be seen at the line of half-ebb, about half-way between Leith and Portobello. But though about ten feet in height, it is a small stone, compared with others of its class both in this 10 110 Li;X GEOLOGY. country and the Continent. The rock, as it is well termed (tor it is a mass of granite weighing fifteen hundred tons), on which the colossal statue of Peter the Great at St. Petersburg is plaivd, is a travelled boulder, which was found dissociated from every other stone of its kind in- the mi Idle of a morass; and Sir Roderick Murchison describes, in one of his papers on the Northern Drift, a Scandinavian boulder thirty feet in height by one hundred and forty in circumference. Most, if not all the boulders which we find in this part of the country on the lower zone, have been washed out of the boulder-clay. Wherever we find a group of boulders on the portion of sea-bottom uncovered by the ebb, we have but to look at the line where the surf Itivuks when the sea is at full, and there we find the clay itM-lf, with its half-uncovered boulders projecting from its y'u-lding sides, apparently as freshly grooved and scratched as if the transporting iceberg had been at work upon them but yesterday. I must again adduce the evidence of Sir Charles Lyell, to show that masses of this character are frequently ice- borne. " In the river St. Lawrence," we find him stating in his " Elements," ** the loose ice accumulates on the shoals during the winter, at which season the water is low. The separate fragments of ice are readily frozen together in a climate where the temperature is sometimes thirty degrees below zero, and boulders become entangled with them ; so that in spring, when the river rises on the melting of the snow, the ice is floated ofij frequently conveying the bould- ers to great distances. A single block of granite fifteen ti t long by ten feet both in breadth and height, and which could not contain less than fifteen hundred cubic feet of atone, was in this way moved down the river several hun- dred yards, during the late survey in 1837. Heavy anchors LECTURES ON GEOLOGY. Ill of ships lying on the shore have in like manner been closed in and removed. In October 1808 wooden stakes were driven several feet into the ground at one part of the banks of the St. Lawrence at high-water mark, and over them were piled many boulders as large as the united force of six men could roll. The year after, all the boulders had dis- appeared, and others had arrived, and the stakes had been drawn out and carried away by the ice." Our Scottish boulders though in many instances im- mediately associated, as in this neighborhood, with the boulder-clay, and in many others, as in our moorland dis- tricts, with the bare rock occur in some cases associated with the superficial sands and gravels, and rest upon or over these. And in these last instances they must have been the subjects of a course of ice-borne voyagings subse- quent to the earlier course, and when the land was rising. Even during the last sixty years, though our winters are now far from severe, there have been instances in Scotland of the transport of huge stones by the agency of ice ; and to two of these, as of a character suited to throw some light on the boulder voyagings of the remote past, I must be permitted to refer. Some of my audience may have heard of a boulder well known on both sides of the Moray Frith as the " Travelled Stone of Petty," a district which includes the Moor of Culloden, and at whose parish church Hector Boece saw the gigantic bones of the colossal Little John. The Clack dim n-Aban, or black stone of the white bog, for such is the graphically descriptive Gaelic name of the moss, measures about six feet in height by from six to seven feet in breadth and thickness, and served, up to the 19th of February 1799, as a march-stone between the properties of Castle Stuart and Culloden. It lay just within flood- 1!J LHCTUKES OX GKOI/xiY. mark, near where a little stream empties itself into a shallow sandy bay. There had been a severe, long-continued frost throughout the early part of the month; and the upper portions of the bay had acquired, mainly through the agency of the streamlet, a continuous covering of ice, that had attained, round the base of the stone, which it clasped a thickness of eighteen inches. On the night of the I'.ith the tide rose unusually high on the beach, and there broke out a violent hurricane from the east-south-east, ac- companied by a snow-storm. There is a meal mill in the immediate neighborhood of the stone ; and when the old miller as he related the story to the late Sir Thomas Dick Lander got up on the morning of the 20th, so violent was the storm, and so huge the snow-wreaths that blocked up every window and door, and rose over the eaves, that he could hardly make his way to his barns, a journey of but a few yards ; and in returning again from them to his dwell- ing, he narrowly escaped losing himself in the drift. In looking towards the bay, in one of the pauses of the storm, he could scarce credit his eyesight : the immense Clach du n-Aban had disappeared, vanished, gone clean off the ground ; and he called to his wife in astonishment and alarm, that the "meikle stane was awa." The honest woman looked out, and then rubbed her eyes, as if to verify their evidence ; but the fact was unquestionable, the u meikle stane " certainly " was awa ; " and there remained but a hollow pit in the sand, with a long, shallow furrow, stretching from the pit outwards to where the snow rhime closed thick over the sea, to mark where it had been. When, however, the weather cleared up, the stone again lu came vi>ille, lying out in the sands uncovered by the ebb, seven hundred and eighty feet from its former position. In the evening of the day, the neighbors flocked out by LECTUKES ON GEOLOGY. 113 scores to examine the scene of so extraordinary a prodigy. Where the stone had lain they found but the deep dent connected by the furrow which lay athwart the bay in the line of the hurricane, with the stone itself, around the base of which there still projected a thick cornice of ice. In its new position the stone still lies ; and only a few years ago mayhap, still a wooden post which marked the point where the two contiguous properties met, marked also the spot from which, after a rest of ages, it had set out on its short voyage. My other case of boulder travelling in some respects a more curious case than the one related occurred early in the present century on the eastern coast of Sutherland- shire. Near the small hamlet of Torribal, in the upper part of Loch Fleet, there stood, about fifty years ago, a rude obelisk of undressed stone, generally regarded as Danish, which, though more ancient than authentic history, or even tradition, in the district, was less so than the old coast line, as it had been evidently erected, subsequent to the last change of level, on the flat marginal strip which intervenes between the old line and the sea. It rose in the middle of a swampy hollow, which protracted rains sometimes con- verted into a strip of water, and which was sometimes swept by the overflowings of the neighboring river. On the eve of the incident which proved the terminating one in its history, the hollow, previously filled with rain-water, had been frozen to the bottom by a continued frost, which was, however, on the eve of breaking up ; and a dense fog lay thick in the valley, when a benighted Highlander, re- turning tipsy from a market by the light of the moon, came staggering in the direction of the standing stone, and in a drunken frolic set his bonnet on the top of it ; and then wandering off into the mist, he lost sight of both stone and 10* 114 LECTURES ON GEOLOGY. bonnet, and, failing to regain them, lie bad to return bare- headed to his home. The thaw came on ; the river rose <.\ i r its banks; the ice-cake around the obelisk floated high above the level, wrenching up the obelisk along with it, as the ice of the St. Lawrence wrenched up the stakes de- scribed by Sir Charles Lyell ; and both ice-cake and obelisk floated down the loch to the sea. As the morning broke a fierce morning of flood and tempest they were seen pass- ing what some forty years ago was known as the Little Ferry ; and the alarm went abroad along the shores on both .-ides, that there was a man standing in the middle of the Loch on the floating ice, and in course of being swept out to the ocean. Poor man! he had been crossing the river, it was interred, when the ice broke up ; and though the en- terprise was a somewhat perilous one, for the ice fragments were rushing furiously along on the wild tides of the loch, maddened by the inundation, a boat, double manned, shot out from the shore to the rescue, and soon neared the drift- ing ice-floe. It was ultimately seen, however, that the supposed man was but a Danish obelisk, bearing on its head a m\>terious bonnet; and bonnet and obelisk were left to find their way to the German Ocean, in which it is proba- ble they now both lie. These modern instances of boulder travelling may serve to show how huge stones originally associated with the boulder-clay may have come to rest on the arenaceous or gravelly deposits which overlie it. Through the second voyage of the Petty boulder, it was deposited on a recently formed bed of sand ; and the stand- ing-stone of Torribal may now rest on sea-shells that were living half a century ago. It is held by geologists of high standing, that after the period of submergence represented by the boulder-clays of our country, the British islands were elevated to such a LECTURES ON GEOLOGY. 115 * height over the sea-level, that their distinctive character as islands was lost, and the area which they occupy united to the main land in the character of a western prolongation of the great European continent. It was at this period, says Professor Edward Forbes, that Britain and Ireland received, over the upraised bed of the German Ocean, their Germanic flora, the last acquired of the five floras which compose their vegetation. The evidence on the point, however, still seems somewhat meagre. I can have no doubt that the land stood considerably higher during this Post-Tertiary period than it does now. As shown by the dressed surfaces and rounded forms of many of the smaller islets of the north-western coasts of Scotland, and the markings at the bottom of its lochs and estuaries, and on the rocks along their shores, the latter glaciers must have descended from the central hills of the country far below the present sea-level ; and we find some of the transverse moraines which they ploughed up before them in their descent existing as gravelly spits, that rise amid the waves, in the middle of long friths or at the entrance of deep bays. I have seen, too, on rocky coasts, considerably below the tide-line at flood, a sort of recent breccia formed by cal- careous springs, which, as the stalagmitical matter could not have been deposited in places exposed to the diurnal washings of the sea, indicated a higher level of the land than now, at the time of its formation ; and the submerged mosses of both Britain and Ireland mosses now existing in many localities far below the fall of the tide bear evi- dence, where not more ancient than the boulder-clay, in the same line. But on this obscure passage in the geological history of our country I am unable, from at least actual observation, to say aught more : my few facts lie in the direction of Professor Forbes's theory, but they accompany 116 LECTURES ON GEOLOGY. it only a short way. There is a wide gap still unfilled. I may In- permitted to remind you, that it is lield by the Professor one of the most accomplished of our geolo- gists that of the five British floras, we have two in Scotland, the Germanic flora, and the semi-arctic or Scandinavian flora; that these were introduced into the country at different periods ; and that while the Germanic flora dates from the times of the Post-Tertiary elevation of the land, the more ancient of the two the semi-arctic or Scandinavian dates from the preceding times of the boulder-clay. Nor does it appear in any degree more im- probable that we should have the descendants of the plants of even the remoter period still vital on our hill-tops, than that we should have the descendants of some of its animals still living in our seas. It seems at first a curious problem, ditlicult of solution, that widely separated mountain sum- mits should possess the same alpine plants, that the sum- mits of Ben Wyvis and Ben Lomond, for instance, or of r. 11 Nevis and Ben Muich Dhui, should have their species in common, while not a trace of them appears on the lower elevations between. But it simplifies the case to conceive of these alpine plants as the vegetable aborigines of the country, compelled by climatal invasion to shelter in its last bleak retreats, where the winter snows linger unwasted till midsummer, and the breeze is always laden with the chills of the old glacial period. They compose the Celtic portion of the Scottish flora, cooped up in their mountain recesses by the encroachments of those Gennanic races of the plant family that flourish, in the altered atmos- I -In -re, or the more genial plains of the country, or on the sunny slopes of its lower hills. That language of flowers in which tin- ladies of Mohammedan countries have learned to converse is not unappropriated)- employed in giving LECTURES ON GEOLOGY. 117 expression to the various modes of a passion scarce less evanescent than the flowers themselves. But is it not passing strange, that we of Scotland should be called on to recognize in the transitory flowers of our sheltered low-lying plains and valleys, and of our high, bleak moors and exposed mountain summits, the records of an antiq- uity so remote, that the stories told by the half-effaced hieroglyphics of Nineveh and of Egypt are of yesterday in comparison ? Here the exhibition of our facts illustrative of the Pleis- tocene and Post-Tertiary periods in Scotland properly ends. The existing evidence has been taken, though, of course, briefly and imperfectly, the extent and multiplicity of the subject considered ; and, the record closed, a formal summary of the conclusions founded upon it should now terminate our history. Permit me, however, to present you, in conclusion, not with the formal summary, but a somewhat extended picture, of the whole, exhibited, pan- orama-like, as a series of scenes. The fine passage in the Autumn of Thomson, in which the poet lays all Scotland at once upon the canvas, and surveys it at a glance, must be familiar to you all : " Here awhile the Mase, High hovering o'er the broad cerulean scene, Sees Caledonia in romantic view; Her airy mountains, from the waving main, Invested with a keen diffusive sky, Breathing the soul acute ; her forests huge, Incult, robust, and tall, by Nature's hand Planted of old; her azure lakes between, Poured out extensive, and of watery wealth Full; winding deep and green, her fertile vales, With many a cool, translucent, brimming flood "NVash'd lovely, from the Tweed (pure parent stream, Whose pastoral banks first heard my Doric reed, 118 LECTURES ON GEOLOGY. With, sylvan .Ted, thy tributary brook), To where the North's inflated tempest foams O'er Orcas or Bctubium's highest peak." Let us in like manner attempt calling up the features of our country in one continuous landscape, as they appeared at the commencement of the glacial period, just as the paroxysm of depression had come on, and bold headland and steep iron-bound islet had begun slowly to settle into the sea. The general outline is that of Scotland, though harsher and more rugged than now, for it lacks the softening in- tegument of the subsoils. Yonder are the Grampians, and yonder the Cheviots, and, deeply indenting the shores, yon- der are the well-known estuaries and bays, the friths of Forth, Tay, and Moray, and the long withdrawing lakes, Loch Katrine, and Loch Awe, and Loch Maree, and the far-gleaming waters of the deep Caledonian Valley, the Ness, and the Oich, and the Lochy. But though the sum- mer sun looks down upon the scene, the snow-line de- scends beneath the top of even our second-class mountains; and the tall, beetling Ben Nevis, and graceful Ben Lomond, and the broad-based Ben Muich Dhui, glitter in the sun- shine, in their coats of dazzling white, from their summits half-way down to their bases. There are extended forests of the native fir on the lower plains, mingled with the slim- mer forms and more richly-tinted foliage of the spruce pine. On the upper grounds, thickets of stunted willows ami straggling belts of diminutive birches skirt the ravines and water-courses, and yellow mosses and gray lichens form the staple covering of the humbler hill-sides and the moors. But the distinctive feature of the country is its glaciers. Fed by the perpetual snows of the upper heights, the deeper valleys among the mountains have their rigid LECTUIKS ON GEOLOGY. 119 ice-rivers, that in the narrower friths and lochs of the western and northern coasts shoot far out, mole-like, into the tide. And, lo ! along the shores, in sounds and bays never yet ploughed by the keel of voyager, vast groups of icebergs, that gleam white to the sun, like the sails of distant fleets, He moveless in the calm, or drift slowly along in rippling tideways. Nor is the land without its inhabi- tants, though man has not yet appeared. The colossal elephant, not naked and dingy of coat, like his congener of the tropics, but shaggy, with long red hair, browses among the woods. There is a stronsc-limbed rhinoceros wallow- o ing in yonder swamp, and a herd of reindeer cropping the moss high on the hill-side beyond. The morse is basking on that half-tide skerry; and a wolf, swept seawards by the current, howls loud in terror from yonder drifting ice- floe. We have looked abroad on our future country in the period of the first local glaciers, ere the submergence of the land. Ages pass, and usher in the succeeding period of the boulder-clay. The prospect, no longer that of a continu- ous land, presents us with a wintry archipelago of islands, broken into thre/3 groups by two deep ocean-sounds, the ocean-sound of the great Caledonian Valley, and that of the broader but shallower valley which stretches across the island from the Clyde to the Forth. We stand full in front of one of these vast ocean-rivers, the southern one. There are snow-enwrapped islets on either side. Can yon- der thickly-set cluster be the half-submerged Pentlands? and yonder pair of islets, connected by a low, flat neck, the eastern and western Lomonds ? and yonder half-tide rock, blackened with algas, and around which a shoal of porpoises are gamboling, the summit of Arthur Seat ? The wide sound, now a rich agricultural valley, is here studded by 1^0 LECTURES OX GEOLOGY. its fleets of tall icebergs, there cumbered by its level fields of drift ice. Nature sports wantonly amid every variety of form ; and the motion of the great floating masses, cast into shapes with which we associate moveless solidity, adds to the magical effect of the scene. Here a flat-roofed temple, surrounded by colonnades of hoar and wasted columns, comes drifting past ; there a cathedral, furnished with towers and spire, strikes heavily against the rocky bottom, many fathoms beneath, and its nodding pin- nacles stoop at every blow. Yonder, already fast aground, there rests a ponderous castle, with its curtained towers, its arched gateway, and its multitudinous turrets, reflected on the calm surface beneath ; and pyramids and obelisks, buttressed ramparts, and embrazured watch-towers, with shapes still more fantastic, those of ships, and trees, and brute and human forms, crowd the retiring vista beyond. There is a scarce less marked variety of color. The in- tense white of the field-ice, thinly covered with snow, and glittering without shade in the declining sun, dazzles the eye. The taller icebergs gleam in hues of more softened radiance, here of an emerald green, there of a sapphire blue, yonder of a paly marble gray ; the light, polarized by a thousand cross reflections, sports amid the planes and facets, the fissures and pinnacles, in all the rainbow gor- geousness of the prismatic hues. And bright over all rise on the distant horizon the detached mountain-tops, now catching a flush of crimson and gold from the setting lumi- navy. But the sun sinks, and the clouds gather, and the night comes on black with tempest ; and the grounded ni;ii's, moved by the violence of the aroused winds, grate heavily along the bottom; and while the whole heavens are foul with sleet and snow-rack, and the driving masses clash in rude collision, till all beneath is one wide stun- LECTURES ON GEOLOGY. 121 ning roar, the tortured sea boils and dashes around them, turbid with the comminuted debris of the fretted rocks below. The vision belongs to an early age-of the boulder-clay : it changes to a later time ; and the same sea spreads out as before, laden by what seem the same drifting ice-floes. But the lower hills, buried in the profound depths of ocean, are no longer visible ; the Lainmermuirs have disappeared ; and the slopes of Braid and Duddingstone, with " North Berwick Law, with cone of green, And Bass amid the waters; " and we can determine their place by but the huger ice- bergs that lie stranded and motionless on their peaks ; while the lesser masses drift on to the east. Moons wax and wane, and tides rise and fall ; and still the deep cur- rent of the gulf stream flows ever from the west, traversing the wide Atlantic, like some vast river winding through an enormous extent of meadow ; and, in eddying over the submerged land, it arranges behind the buried eminences, in its own easterly line, many a long trail of gravel and debris, to form the Crag and Tail phenomenon of future ge- ologists. As we extend our view, we may mark, far in the west, where the arctic current, dotted white with its ice- mountains and floes, impinges on the gulf stream ; and where, sinking from its chill density to a lower stratum of sea, it gives up its burden to the lighter and more tepid tide. A thick fog hangs over the junction, where the warmer waters of the west and south encounter the chill, icy air of the north ; and, steaming forth into the bleak at- mosphere like a seething cauldron, the cloud, when the west wind blows, fills with its thick gray reek the recesses of the half-foundered land, and obscures the prospect. 11 LECTURES ON GEOLOGY. Anon there is another change in the dream. The long period of submergence is past; the country is again rising; and, under a climate still ungenial and severe, the glaciers lengthen out seawards, as the land broadens and extends, till the northern and western Highlands seem manacled in ice. Even the lower hill-tops exhibit an alpine vegetation, beautiful, though somewhat meagre ; while in the friths and bays, the remote ancestors of many of our existing shells that thrive in the higher latitudes, still mix, as at an earlier period, with shells whose living representatives are now to be sought on the coasts of northern Scandinavia and Greenland. Ages pass ; the land rises slowly over the deep, terrace above terrace ; the thermal line moves grad- ually to the north ; the line of perpetual snow ascends be- yond the mountain summits; the temperature increases; the ice disappears ; the semi-arctic plants creep up the hill-sides, to be supplanted on the plains by the leafy denizens of happier climates ; and at length, under skies such as now look down upon us, and on nearly the existing breadth of land, the human period begins. The half-naked hunter, armed with his hatchet or lance of stone, pursues the roe or the wild ox through woods that, though comparatively but of yesterday, already present appearances of a hoar antiquity; or, when the winter snows gather around his dwelling, does battle at its beleaguered threshold with the hungry wolf or the bear. The last great geologic change takes place : the coast line is suddenly elevated ; and the country presents a new front to the sea. And on the widened platform, when yet other ages have come and gone, the historic period commences, and the light of a classical literature falls for the first time on the incidents of Scottish story, and on the bold features of Scottish character. LECTURES ON GEOLOGY. 123 It is said that modern science is adverse to the exercise and development of the imaginative faculty. But is it really so ? Are visions such as those in which we have been indulging less richly charged with that poetic pabu- lum on which fancy feeds and grows strong, than those ancient tales of enchantment and faery which beguiled of old, in solitary homesteads, the long winter nights ? Be- cause science flourishes, must poesy decline ? The com- plaint serves but to betray the weakness of the class who urge it. True, in an age like the present, considerably more scientific then poetical, science substitutes for the smaller poetry of fiction, the great poetry of truth ; and as there is a more general interest felt in new revelations of what God has wrought, than in exhibitions of what the humbler order of poets have half borrowed, half invented, the disappointed dreamers complain that the "material laws " of science have pushed them from their place. As well might the Arab who prided himself upon the beauty of some white tent which he had reared in some green oasis of the desert, complain of the dull tools of Belzoni's laborers, when engaged in clearing from the sands the front of some august temple of the ancient time. It is not the tools, it might be well said to the complainer, that are competing with your neat little tent ; it is the sublime edifice, hitherto covered up, which the tools are laying bare. Nor is it the material laws, we may, on the same principle, say to the poets of the querulous cast, that are overbearing your little inventions, and making them seem small ; but those sublime works and wonderful actings of the Creator which they unveil, and bring into comparison with yours. But from His works and His actings have the masters of the lyre ever derived their choicest materials ; and whenever a truly great poet arises, one that will 124 LECTURES ON GEOLOGY. add a profound intellect to a powerful imagination, he will find science not his enemy, but an obsequious caterer and a devoted friend. He will find sermons in stones, and more of the suggestive and the sublime in a few broken scaurs of clay, a few fragmentary shells, and a few green reaches of the old coast line, than versifiers of the ordinary calibre in their once fresh gems and flowers, in sublime ocean, the broad earth, or the blue firmament and all its stars. LECTURE THIRD. The Poet Delta (Dr. Moir) His Definition of Poetry His Death His Burial- place at Inveresk Vision, Geological and Historical, of the Surrounding Country What is it that imparts to Nature its Poetry The Tertiary Forma- tion in Scotland In Geologic History all Ages contemporary Amber the Resin of the Pinits succinifer A Vegetable Production of the Middle Tertiary Ages Its Properties and Uses The Masses of Insects inclosed in it The Structural Geology of Scotland Its Trap Rock The Scenery usually asso- ciated with the Trap Rock H ow formed The Cretaceous Period in Scotland Its Productions The Chalk Deposits Death of Species dependent on Laws different from those which determine the Death of Individuals -r- The Two great Infinites. THE members of the Philosophical Institution of Edin- burgh enjoyed the privilege last season of listening to one of the sweetest and tenderest of modern British poets eloquently descanting on the history of modern British poetry. Rarely had master established for himself a bet- ter claim to teach. And, regarding the elegant volume produced on that occasion, so exquisite in its taste and so generous in its criticisms, it may justly be said that perhaps its only, at all events its gravest defect, is the inevitable one that, in exhibiting all that during the bypast genera- tion was most characteristic and best in the poesy of our country, it should have taken no cognizance of the poetry of Delta. Dr. Moir had just finished his course, but his volume had not yet appeared, when, urged by a friend, I perhaps too rashly consented to contribute two lectures to a course then delivering in the native town of the poet; and in one of these I expressed the conviction to which I 11* 126 LECTURES ON GEOLOGY. gave utterance last season in this place, that there is no incompatibility between the pursuit of geologic science and a genial development of the poetic faculty. Dr. Moir had honored my address with his presence ; he had listened with apparent attention to a view very much opposed, as I was told after the breaking up of the meeting, to one which he himself had promulgated to the Institution only a few weeks before ; and on the publication of his little volume, he politely sent me a copy, accompanied by a kind note, in which he referred to the point apparently at issue between us as involving rather a seeming than a real dif- ference. "Our antagonism respecting the relations of poetry and science," he said, " is, I doubt not, much more apparent than real, and arises simply from the opposite aspects in which we have regarded the subject." I read his work with interest; and at first deemed the differ- ence somewhat more than merely apparent. I found the lecturer speaking of " staggering blows" inflicted on the poetry of the age by science in not a few formidably prosaic shapes, in the shape, among the rest, of "geolog- ic-ill exposition ;" and of " rocks stratified by the geologists as satins are measured by mercers," and, in consequence, no longer redolent of that emotion of the sublime which was wont to breathe forth of old from broken crags and giddy precipices. But his definition of poetry reassured me, and set all right again. "Poetry," he said, "may be defined to be objects or subjects seen through the mirror of imagination, and descanted on in harmonious language ; and if so, it must be admitted that the very exactness of knowledge is a barrier to the laying on of that coloring by which facts can be invested with the illusive hues of poetry. Wherever light penetrates the obscure and illuminates the uncertain, we may rest assured that a demesne has been LECTURES ON GEOLOGY. 127 lost to the realms of imagination." Now, if such be poe- try, I said, and such the conditions favorable to its devel- opment, the poets need be in no degree jealous of the geologists. The stony science, with buried creations for its domains, and half an eternity charged with its annals, possesses its realms of dim and shadowy fields, in which troops of fancies already walk like disembodied ghosts in the old fields of Elysium, and which bid fair to be quite dark and uncertain enough for all the purposes of poesy for centuries to come. Alas ! only a/ew weeks after, amid hundreds of his sor- rowing friends and townsmen, I followed the honored re- mains of the poet to the grave; and heard, in that old, picturesque burying-ground which commands on its green ridge the effluence of the Esk, the shovelled earth falling heavy on the coffin-lid. It was a lovely day of chequered shadow and sunshine ; and the wide frith slept silently in the calm, with a dream-like spectrum of the heavens mir- rored on its bosom. From the sadness of the present my thoughts let themselves out upon the past. I stood among the groves on a grassy mound which had been reared by the old Roman invader greatly more than a thousand years before ; and I bethought me how, on visiting the place a few twelvemonths previous, for the first time, I had first of all sought out the burying-ground of the family of the deceased, a spot endeared to every lover of poesy by those tenderest and sweetest of "domestic verses" which show how truly, according to Cowper, " the poet's lyre " had been " the poet's heart ; " and how I had next set my- self to trace, as next in interest, the remains of that stern old people whose thirst of conquest and dominion had led them so far. And lo ! like a dream remembered in a dream, as the crowd broke up and retired, the visions of 128 LECTURES ON GEOLOGY. that quiet day were again conjured up before me, but bear- ing now a felt reference to the respected dead, and accom- panied by the conviction that, had we been destined to meet, and to compare at length our respective views, we should have found them essentially the same. On that rising ground, so rich in historic associations, both Somerset and Cromwell had planted their cannon, and it had witnessed the disaster at Pinkie, and the head- long flight of the dragoons of Cope. But, passing over the more recent scenes, the vision of a forest-covered coun- try rose before me, a vision of the ancient aboriginal woods rising dusky and brown in one vast thicket, from the windings of the Esk to the pale brow of the Pent- lands. Nor was the landscape without its human figures. The grim legionaries of the Proconsul of Augustus were opening with busy axes a shady roadway through the midst ; and the incessant strokes of the axe and the crash of falling trees echoed in the silence throughout the valley. And then there arose another and earlier vision, when the range of semicircular heights which rise above the ancient Saxon borough, with its squat tower and antique bridge, existed as the coast, line, and the site of the town itself as a sandy bay, swum over by the sea-wolf and the seal ; and the long ridge now occupied by garden and villa, church and burying-ground, as a steep, gravelly bar, heaped up in the vexed line, where the tides of the river on the one hand contended with the waves of the Frith on the other; and the Esk, fed by the glaciers of the interior, whose blue gleam I could mark on the distant Lammermoors and the steeper Pentlands, rolled downwards, a vast stream, that filled from side to side the ample banks which, even when heaviest in flood, it scarce half fills now ; while a scantier and dingier foliage than before, composed chiefly of taper LECTURES ON GEOLOGY. 129 spruce and dark pine, roughened the lower plains, and flung its multitudinous boughs athwart the turbid and troubled eddies. And then there arose yet other and remoter scenes. From a foreground of weltering sea I could mark a scattered archipelago of waste, uninhabited islands, picturesquely roughened by wood and rock; and near where the Scottish capital now stands, a submarine volcano sent forth its slim column of mingled smoke and vapor into the sky. And then there rose in quick succes- sion scenes of the old Carboniferous forests: long with- drawing lakes, fringed with dense thickets of the green Calamite, tall and straight as the masts of pinnaces, and inhabited by enormous fishes, that glittered through the transparent depths in their enamelled armor of proof; or glades of thickest verdure, where the tree-fern mingled its branch-like fronds with the hirsute arms of the gigan- tic club-moss, and where, amid strange forms of shrub and tree no longer known on earth, the stately Araucarian reared its proud head two hundred feet over the soil ; or yet again, there rose a scene of coral bowers and encrinal thickets, that glimmered amid the deep green of the an- cient ocean, and in which, as in the groves sung by Ovid, the plants were sentient, and the shrinking flowers bled when injured. And, last of all, on the further limits of organic life a thick fog came down upon the sea, and my excursions into the remote past terminated, like the voy- age of an old fabulous navigator, in thick darkness. Each of the series of visions, whether of the comparatively re- cent or the remote past, in which I at that time indulged, had employed the same faculties and gratified the same feelings ; and though, in surveying the stuff out of which they had been sublimed, I could easily say where the his- toric ended and the geologic began, no corresponding line 130 LECTURES ON GEOLOGY. indicated in the visions themselves where the poetry ended and the prose began. The visions, whether historic or geologic, "were of imagination all compact." They all involved the same processes of mind though, of course, in this instance mind of a humbler order and ruder tex- ture as those exhibited in the sweet and fragrant verse of the poet himself, as those exercised, let me say, in his vision on " Mary's Mount," when, with quiet graves above, and surrounded by quiet fields, he saw the contending hosts of a former day thronging the lower ground, and, " With hilt to hilt, and hand to hand, The ehildren of our mother land To battle came;" or when he called up, after the lapse of half a lifetime, how when, in a wintry morning, he had journeyed before daybreak, a happy boy, along the frozen Esk, and saw " In the far west the Pentland's gloomy ridge Belting the pale blue sky, whereon a cloud, Fantastic, gray, and tinged with solemn light, Lay like a dreaming monster, and the moon, Waning, above its silvery rim upheld Her horns, as 't were a spectre of the past." I shall continue to hold, therefore, that there was no real difference between the views of the poet and those which I myself entertain, but that, as he himself well expressed it, our apparent antagonism arose simply from the oppo- site aspects in which we had viewed the subject." He had been thinking of but stiff diagrams and hard names, of dead strata measured off, in "geological exposition," by the yard and the mile, and enveloped in the obscuring folds of a Babylonish phraseology; while I, looking through the crooked characters and uncouth sounds in which the LECTURES ON GEOLOGY. 131 meanings of the science are locked up, to the meanings ^ themselves, was luxuriating among the strange, wild narra- tives and richly poetic descriptions of which its pregnant recoi'ds consist. What is it, let me ask, that imparts to Nature its poe- try? It is not in Nature itself; it resides not either in dead or organized matter, in rock, or bird, or flower; " the deep saith it is not in me, and the sea saith it is not in me." It is in mind that it lives and breathes : external nature is but its storehouse of subjects and models; and it is not until these are called up as images, and invested with " the light that never was on land or sea," that they cease to be of the earth earthy, and form the ethereal stuff of which the visions of the poet are made. Nay, is it not mainly through that associative faculty to which the sights and sounds of present nature become suggestive of the images of a nature not present, but seen within the mind, that the landscape pleases, or that we find beauty in its woods or beside its streams, or the impressive and the sub- lime among its mountains and rocks? Nature is a vast tab- let, inscribed with signs, each of which has its own signifi- cancy, and becomes poetry in the mind wh'en read ; and geology is simply the key by which myriads of these signs, hitherto undecipherable, can be unlocked and perused, and thus a new province added to the poetical domain. We are told by travellers, that the rocks of the wilderness of Sinai are lettered over with strange characters, inscribed during the forty years' wanderings of Israel. They testify, in their very existence, of a remote past, when the cloud- o'ershadowed tabernacle rose amid the tents of the desert; and who shall dare say whether to the scholar who could dive into their hidden meanings they might not be found charged with the very songs sung of old by Moses and by 132 LECTURES ON GEOLOGY. Miriam, when the sea rolled over the pride of Egypt? To the geologist every rock bears its inscription engraved in ancient hieroglyphic characters, that tell of the Creator's journeyings of old, of the laws which He gave, the tab- ernacles which He reared, and the marvels which He wrought, of mute prophecies wrapped up in type and symbol, of earth gulfs that opened, and of reptiles that flew, of fiery plagues that devastated on the dry land, and of hosts more numerous than that of Pharaoh, that "sank like lead in the mighty waters;" and, having in some degree mastered the occult meanings of these strange hieroglyphics, we must be permitted to refer, in asserting the poetry of our science, to the sublime revelations with which they are charged, and the vivid imagery which they conjure up. But our history lags in its progress, while we discuss the poetic capabilities of the study through which its records are read and its materials derived. In the deposits of that Tertiary division of the geologic formation which represents in the history of the globe the period during which mammals began to be abundant, and in which the great Cuvier won his laurels, Scotland is one of the poorest of European countries. Save for the com- paratively recent discovery of Tertiary beds in the island of Mull by a nobleman fitted by nature either to adorn the literature or extend the science of his country, the geological historian would have to pass direct from the Pleistocene beds, with their grooved and polished pebbles and their semi-arctic shells, to the Chalk fossils of Banff and Aberdeen. But the discovery of his Grace the Duke of Argyll furnishes us with an interesting glimpse of a middle period widely different in its character from either the Cretaceous system or the boulder-clay. In the island of Mull, in a headland that rises about one hundred and thirty LECTURES ON GEOLOGY. 133 feet over the sea, there occur, interposed between thick beds of trap, three comparatively thin beds of a gray are- naceous shale, charged with fossil leaves, as beautifully spread out, and with their ribs and veins as distinctly vis- ible, as if they had been preserved in the herbarium of a botanist. Most of them belong to extinct species of exist- ing families of dicotyledonous trees, such as the plane and the buckthorn, mingled, however, with narrow linear leaves of cone-bearing trees,. which are supposed to belong, in this instance, to a species of yew, and with what seem the fronds of fern and the stems of equisetacea. Some of the beds of coal which have been long known to occur among the traps of the island of Mull are regarded by the Duke of Argyll as prolongations of these Tertiary leaf-beds, so mineralized by some metamorphic action as to have lost the organic structure. There must have been vast accu- mulations of leaves ere they could have yielded beds of coal. The middle or second bed of the three his Grace describes as peculiarly rich in the leafy impressions of this ancient period ; and I need scarce say how suggestive the glimpse is which is furnished us by these buried layers of the foliage of Tertiary forests in Scotland, of which no other known memorial remains. You all remember Cole- ridge's fine comparison of the sorely-worn sails of the vessel in which the ancient mariner performed his voyage of peril and prodigy, to " Brown skeletons of leaves that lay The forest brook along, When the ivy tod is heavy with snow, And the owlet whoops to the wolf below; " and you must have often marked the extreme delicacy of those deposited leaves, macerated during the winter sea- 12 134 LECTURES ON GEOLOGY. son at the bottom of some woodland pool, which sug- gested the poet's simile. In that Tertiary period to which the leaf-beds of Mull belong, it would seem that extensive forests, chiefly of deciduous trees, shed year after year their summer coverings of leaves, some of which fell, and some of which were blown by the autumnal gusts, into the streams of the country, and were swept down by the cur- rent to lakes or estuaries, where they lay gradually resolv- ing into such brown skeletons as caught the eye of Cole- ridge. We learn further, that there were forces active at the time, of which at any later period we have had no examples in the British islands. One of the leaf-beds described by his Grace is overlaid by a bed of volcanic ashesor tuff seven feet thick ; another by a bed of similar ashes mixed with chalk flints, twenty feet thick ; and yet another the topmost layer bears over it a bed of over- flowing columnar basalt, forty feet thick. The volcanic agencies were active in what is now Scotland during the ages of its Tertiary forests. The only Tertiary fossils of Scotland yet discovered are these forest and fern leaves of the Mull deposits. Their place in the great geologic division to which they belong is still definitely to fix ; but some of our higher geologists are, I find, disposed to refer them to the second Tertiary or Miocene epoch, though with considerable hesitation. They belong, it is probable, to a period not very widely removed from that of the richly fossiliferous Marlstone of (Eningen, on the banks of the Rhine, with its vast abun- dance of plants, chiefly dicotyledonous, of fishes specifi- cally different from those which now exist, but of the existing genera, of a fox, which only the comparative anatomist can distinguish from the recent species of this country, and of reptiles generically akin to those of LECTURES ON GEOLOGY. 185 the United States. It is a curious fact that, both in its animal and vegetable productions, that part of the New World which borders upon the Atlantic in the temperate zone, from Carolina to the mouth of the St. Lawrence, still presents very much the appearance which was presented by the flora and fauna of Europe during the later Tertiary periods. It has been often remarked, in reference to human manners and the progress of civilization, that all ages of the world may be regarded as contemporary. Man is still in many of the South Sea Islands what he was in our own country previous to the times of the Roman invasion ; and there are provinces in Spain and Portugal in which neither the people nor the clergy have got be- yond the semi-barbarism of the Middle Ages. Curiously enough, in geologic history also, though in a narrower and more restricted sense, all ages are contemporary. The Galapagos have their age of reptiles, New Zealand its age of birds, and New Holland its age of marsupial quad- rupeds. These countries bear now, in not a few par- ticulars, the character of the Oolitic period in our own country. Again, on the eastern coasts of North America we are presented with a vegetation greatly resembling that of some of the later Tertiary periods ; and of several of its animals the type is still more ancient. America, though emphatically the New World in relation to its discovery by civilized man, is, at least in these regions, an old world in relation to geological type ; and it is the so-called Old World that is in reality the new one. " If we compare," says Professor Agassiz, in his late admirable work, " Lake Superior," "if we compare a list of the fossil trees and shrubs from the Tertiary beds of GEningen with a cata- logue of the trees and shrubs of Europe and North Amer- ica, it will be seen that the differences scarcely go beyond 136 LECTURES ON GEOLOGY. those shown by the different floras of these continents under the same latitudes. But what is quite extraordi- nary and unexpected is the fact, that the European fossil plants of that locality resemble more closely the trees and shrubs which grow at present in the eastern parts of North America, than those of any other part of the world ; thus allowing us to express correctly the difference between the opposite coasts of these continents, by saying that the present eastern American flora, and, I may add, the fauna also, have a more ancient character than those of Europe. The plants, especially the trees and shrubs growing in our days in the United States, are, as it were, old-fashioned ; and the characteristic genera Lagoings, Chelydra, and the large Salamanders, with permanent gills, that remind us of the fossils of CEningen, are at least equally so ; they bear tfie marks of former ages? This interesting fact vouched for by assuredly no mean authority may enable us to conceive of the general aspect of our country, so far at least as its appearance depended on its vegetation, to- wards the close of the Miocene period. Old Scotland ex- hibited features in that age greatly resembling those pre- sented to the puritan fathers by the forest-covered shores of New England little more than two centuries ago. But no family of man dwelt in its solitary woods ; and, as shown by its widely spread deposits of trap-tuff, and its vast beds of overlying basalt, broken by faults and shifts, its ancient volcanoes had not yet died out, and it must have had its frequent earthquake agues and shaking fits. There is, however, another witness besides the leaf-beds of the island of Mull, which we may properly call into court to give evidence regarding the Tertiary period in Scotland. It is known that from a very early time masses of amber have been occasionally furnished by the north-eastern LECTURES ON GEOLOGY. 137 shores of the kingdom, in especial by that extensive tract of coast which stretches from the Buchan-ness to the Frith of Tay ; and the geologist now recognizes amber as a vegetable production of the Middle Tertiary ages. It is the resin of an extinct pine, which the fossil botanist has only of late learned to term the Pinus succinifer, or amber pine, but which the Prussian peasantry, who gather amber on the southern shores of the Baltic, used for ages to associate with this substance, from its occurrence in a fossil state in the same beds as amber wood. The orna- mental character of this precious resin seems to have been appreciated by the native Scotch at an early period : beads of amber have been found in the old sepulchral barrows of the kingdom. Its value, however, as we learn from the first notice 1 of it which occurs in our written history, that of Hector Boece, has not been always appreciated. After describing it, not very inadequately, as " ane maner of goum or electuar, hewit like gold, and sa attractive of iiatur, that it drawis stra, flax, or hemmes of claethis to it in the samen maner as does an adamant stone grow," he goes on to say, that " twa year afore the comin af [his] buke to licht (1524) thair arrivit an gret lompe of this goum in Buchquhane, als meikle as an hens ; and wes brocht hame by the herdes quhilk wer kepand thair bestis, to thair housis, and cassin in the fere. And becnus they fand an smell and odour thairwith, they scha to thair maister that it wes garand for the trasens that is maid in the kirkes. Thair maister wes ane rud man as thay wer; and tuk bot ane litell part thairof, and left the remanent part behind him as mater of litell effect. All the parts of this goum, quhen it wes broken, wes of hew of gold, and schone lyke the licht of an candell. The maist part of this goum or electuar wes destroyit be rud peple afore 't 12* 138 LECTURES ON GEOLOGY. cam to any wise mannis eirs ; of quhome may be verifyet the proverb, * The sow cares not for balme.' Als sone as I wes advcrtisit thairof, I maid sic diligence that ane pairt of it was brocht me at Aberdene." I may add to this notice of the old chronicler, that up to a com'paratively recent period, ornaments of amber, especially amber beads of large size, or, as they were termed by our ancestors, "lamour beads," were highly valued by the humbler Scotch. That mysterious attractive property which resided in this gem-like resin, and which has since been found pregnant with that wonderful science to which the substance has given its Greek name, electrum, threw a halo of mystery around it, that served to enhance its native beauty. The Laird of Dumbiedikes was, it must be confessed, neither a very fervent nor very poetical lover ; but a lover he was ; and yet he could find nothing more apt with which to compare the eyes of his mistress, when turned upon him in her gratitude, than to beads of amber. " Dinna ye think," said the laird, "puir Jeanie's e'en, wi' the tears in them, glanced like lamour beads, Mr. Saddletree?" To the geologist this precious 'gum of the Tertiary ages is fraught with a peculiar interest, from the circumstance that it forms the best of all matrices for the preservation of organisms of the more fragile kinds. Mosses, fungi, and liverworts, arc plants of so delicate a structure, that they are rarely or never preserved in shale or stone ; but specimens of all three have been found locked up in amber in a state of the most perfect keeping. And, les containing fragments of the pine which produced it, it has been found to contain minute pieces of four other species of pine, with bits of cypresses, yews, junipers, oaks, poplars, beeches, etc., in all, forty-eight different species of shrubs and trees, which must have flourished in LECTURES ON GEOLOGY. Ib9 the forests where it grew, and which, "viewed in the group, may be regarded as constituting," says Professor Goppert, "a flora of North American character." You will of course remark how directly this evidence bears on that of Professor Agassiz. The most remarkable organ- isms of the amber are, however, its insects, a kind of fossils suggestive of a very different poetry from that which Pope elaborated from them in his well-known simile : "Pretty in amber to observe the forms Of hairs, or straws, or dirt, or grubs, or worms : The things, we know, are neither rich nor rare, But wonder how the mischief they got there! " Fossil insects occur in both the Secondary and Palaeozoic divisions, but rarely indeed in a state of sufficient entire- ness to enable the entomologist to distinguish their spe- cies. Even in classing them into families and genera, our best writers on the subject, such as the Rev. Mr. Brodie', confess that some of the number are very imperfectly made out. In the amber, on the contrary, even the most delicate ephemerae that ever sported for a single summer evening in a forest glade, and then perished as the night came on, are preserved in a state of perfect entireness. In the amber of Prussia eight hundred different kinds of insects have been determined, most of them belonging -A,o species, and even genera, that appear to be distinct from any now known ; while of the others, some are nearly related to indigenous species, and some seem iden- tical with existing forms that inhabit the warmer climates of the south. From their great specific variety and abundance we may infer that insects then, as now, formed the most numerous division of the animal kingdom. Our entomologists reckon at the present time about eleven 140 LECTURES ON GEOLOGY. thousand species of recent British insects, a number many times greater than that of all its v other denizens of the animal kingdom united. You will scarce deem the riddle regarding the entombment of these fragile crea- tures in the amber, which so puzzled the poet, particularly a hard one : the process must have resembled that which we see going on in our pine-forests every summer. The little flutterers must have settled on the bleeding- trunks of the Pinus succinifer, and stuck fast, and the after flow of the sap covered them over. They add an interesting feature, identical with that sung by the poet, to the odor- iferous amber forests of the Tertiary. The hot sun is riding high over the recesses of one of these deep woods, never yet trodden by human foot, and lighting up the waved lines of delicate green with which spring, just pass- ing into early summer, has befringed the dark pines, and the yet unwithered catkins of the poplar and plane, and the white blossoms of the buckthorn. The cave-bear and hyena repose in silence in their dens, and not a wandering breeze rustles among the young leafage. " But hark! how through the peopled air The busy murmur glows; The insect youth are on the wing, Eager to taste the honied spring, And float amid the liquid noon : Some lightly o'er the current skim, Some show their gaily gilded trim Quick glaring to the sun." And lo ! where the forest glade terminates in a brown, primeval wilderness, the sunbeams fall with dazzling brightness on the trunk of a tall, stately tree, just a little touched with decay; and it reflects the light far and wide, and gleams in strong contrast with the gloom of the LECTURES ON GEOLOGY. 141 bosky recesses beyond, like the pillar of fire in the wilder- ness relieved against the cloud of night. 'T is a decaying pine of stateliest size, bleeding amber. The insects of the hour flutter around it ; and when, beguiled by the grate- ful perfume, they touch its deceitful surface, they fare as the lords of creation did in a long posterior age, in that " Serbonian bog, Betwixt Damiata and Mount Casius old, Where armies whole have sunk." But, as happened to so many of the heroes of classic his- tory, death is fame here, and by dying they became im- mortal ; for it is from the individuals who thus perish that future ages are yet to learn that the species which they represent ever existed, or to become acquainted with even the generic peculiarities by which they were distinguished. The question still remains, whence has the amber of our Scottish coasts been derived? It occurs in situ in Tertiary deposits in the neighborhood of London : good specimens of considerable size have been found, for in- stance, in a clay-pit near Hyde Park corner, not a quarter of a mile from the site of the Crystal Palace. It occurs too, in Prussia, in a clay-bed of considerable horizontal extent, of which the larger part lies under the waves of the Baltic, but which rises on some parts of the coast about forty feet over the level of that sea, and to which of late years a sort of classical interest has been given by a modern fiction, worthy, from its air of matter-of-fact truthfulness, of our own Defoe, the "Amber Witch." The black amber vein found by the pastor's little daughter is described in the story as occurring high in a wooded defile behind her father's parsonage, and as owing its black color to the quantity of charcoal, t. e., carbonized wood, 1 1 2 LECTURES ON GEOLOGY. \\ hich it contained. And in both particulars the descrip- tion is true to the geology of the amber deposits. But we have no amber deposits in Scotland ; had amber ever existed in connection with the Tertiary beds of Mull, it would have shared, in all probability, from the close prox- imity of the trap, the fate of the great lumps of butter which that giant in the nursery story who used to eat knights and young ladies, employed in testing the heat of his oven ; and so we must look for its place, not on our shores, but in the seas by which they are washed. But it is here necessary that I should submit to you a brief out- line of the structural geology of our country, not only that we may know in what direction to look for its Ter- tiary beds, but in order also that we may form such an acquaintance with the general framework of our subject, as it exists in space, as may guide us in all our after con- ceptions regarding it. Avoiding the prolixity of minute detail, I shall present you at present with but a few of the Ic.i'ling lines. The great central nucleus of Scotland, presenting con- siderably more than fifteen thousand square miles of sur- face, consists of what we shall term, with the elder geol- ogists, primary rocks, granites, gneisses, mica-schists, quartz-rocks, and clay-slates. These extend in one direc- tion from the southern base of the Grampians to the northern limits of Sutherlandshire, and from Peterhead and Aberdeen on the east to Glenelg and Loch Carron on the west. [N"ow, around this great primary mass there runs a ring of the sedimentary fossiliferous rocks, somewhat, though of course not with such unbroken regularity, as a frame rims round a picture, or as the metallic setting of a ('.uniform or pebble brooch surrounds the stone. Of these earlier fossiliferous rocks, known about the begin- LECTURES ON GEOLOGY. 143 ning of the present century as the Grauwacke, and now as the Silurians, the frame or ring contains but fragments, a narrow strip along the flanks of the Grampians on the south, and a few detached patches along the shores of Banff on the north and east. But the ring or frame of the next oldest fossiliferous system, the Old Red Sand- stone, is very nearly complete ; and to such a breadth do we find it developed, especially in the southern and north- ern parts of the inclosing frame, that, with the addition of a few patches in the border counties of Scotland, we find it occupying nearly five thousand square miles of the sur- face of our country. 1 ] Outside the Old Red Sandstone frame there occurs to the south, in the line of the great flat valley which runs across the country from the Frith of Forth to that of the Clyde, a broad belt of the Coal Measures, the system which succeeds to it in natural sequence ; but on the east, west, and north, the Coal Meas- ures and New Red Sandstone are wanting, and we find fragments of a ring of Lias, as at Applecross, on the one coast, and at Cromarty and Shandwick on the other ; and outside the Lias, considerable fragments of yet another and wider ring of the Oolite. The sea on the east coast, and both that and numerous outbursts of overlying trap 1 The Old Red Sandstone frame, and its corresponding illustrations, no longer hold good. The geology of north-western Scotland has recently been investigated by Sir Roderick Murchison, from whose researches it appears that Silurian strata, occupy a much wider area of that district than had been previously suspected. Aided by Mr. Peach's discovery of Lower Silurian fossils in the crystalline limestones of Sutherlandshire, Sir Roder- ick has succeeded in showing that from the Atlantic to the German Ocean there is a regular succession of strata in ascending order, representing the Laurentian gneiss of Canada and the Cambrian and Lower Silurian rocks of Wales, and superposed upon these older formations in the great Old Red Sandstone of Caithness. See the abstract of Sir Roderick March ison's paper in the Reports of the Leeds Meeting of the British Association. G. 144 LECTURES ON GEOLOGY. on the west, covers up the ring which lies beyond; but the Chalk flints and Greensand fossils of Aberdeen and Banff shires, on the one hand, and the Chalk flints of Mull and Caithness on the other, indicate its existence and its components. An outer ring or frame of Chalk and Green- sand, more or less broken, surrounds on two, mayhap on three sides, the central nucleus of the kingdom ; and were the beds of the German and Atlantic Ocean to be laid dry to the depth of about fifty fathoms, and the area of Scot- land to be proportionally extended, you would find for- mation succeeding formation, in crossing the ring from the nucleus outwards, as we find them succeeding each other in the south of England, when crossing the country from South Wales in the direction of London. Beyond this outer ring of Chalk there lie, it is more than probable, deposits of the Tertiary system. Of. the Mull deposits on the west coast we at least know, though they occur in so disturbed and overflown a district, that they lie outside the Secondary deposits of the island; and again on the east coast, where the Tertiary deposits, which occupy so large a portion of the south-eastern portion of England, outside the Chalk, lose themselves in the German Ocean, the dredge has found interesting trace of them far at sea running northwards, to form, apparently, our submarine belt or ring. It is stated by Woodward, in his " Geology of Norfolk," that the oyster-fishers on that coast dredged up from a tract of oyster-beds near Happesburgh no fewer than two thousand grinders of mammoths in the course of thirteen years. Further, those parts of the Continent which lie opposite our eastern coasts, including Holland, Hanover, and the larger part of Denmark, all consist of deposits of the Tertiary system, which, trending westwards at a low angle, form, it is probable, no inconsiderable part LECTURES ON GEOLOGY. 145 of the bed of the German Ocean. Those beds, however, from which our Scottish amber is derived must lie deep in the sea, outside the Lias, the Oolite, the Greensand, and the Chalk; and our specimens are rare in consequence, because at great depths the bottom is little affected by tempests. Not less than eight hundred pounds weight of this substance has been thrown up on the coast of east Prussia by a single storm. From the Tertiaries we would naturally pass, in our upward progress, to the Secondary deposits ; and of these, the remains of the Cretaceous system, as exhibited in Banff and Aberdeen shires, would, of course, first solicit notice, as representative in Scotland of that portion of the Secondary period nearest our own, the period with which this great middle division* of the earth's history terminated. I must first, however, call your attention to a series of rocks which, without belonging to any of the three great sedimentary divisions, seem in our own coun- tiy to have been contemporary with them all. I refer to the trap rocks of the kingdom. The Duke of Argyle found in the island of Mull, as has been already shown, thick beds of trap, tuffacious and basaltic, overlying beds of the Tertiary division. Again, in the Isle of Skye, Pro- fessor Edward Forbes has detected trap beds which made their way to the surface, and overflowed the shells and corals of the Oolite, about the middle of the great Sec- ondary period. "The thick sheet of imperfectly columnar basalt," says the Professor, " which has so wide an exten- sion in the island of Skye, and plays so important a part in the formation of the magnificent scenery of its coasts, was the product of a submarine eruption, which, if we regard the basalt as an overflow, has its geological date marked to a nicety, having occurred at the close of the 13 14j LKCTURES ON GEOLOGY. middle ami at the commencement of the upper Oolitic period." Yet again, in the neighborhood of Edinburgh, as well described by Mr. Charles M'Laren, there are traps of the Palaeozoic division, beds of stratified tuff, as among the rocks of the Calton Hill, for instance, that belong to the early part of the Carboniferous period ; and I have seen at Oban a conglomerate low in the Old Red Sandstone, formed chiefly of a trap, which even at that early time must have been a surface rock much exposed to denudation. We must regard, then, the trap rocks of Scotland as of all ages, from the earlier Paleozoic to the middle Tertiary periods. The great ganoidal fishes of the Devonian and Carboniferous ages, the huge reptiles of the Oolite, and the gigantic mammals of the Miocene, must have been exposed, in turn, in what is now Scotland, to deluging outbursts of molten matter from the vexed bow- els of the earth, and to overwhelming showers of volcanic ashes. I would, however, crave attention to the curious fact, that during this immensely protracted period of Plutonic activity, the deep-seated agencies operated in nearly the same lines. Masses of the incarcerated matter seem to have made their escape age after age along the same weak parts of their prison walls, the earth's crust; and in Scotland we have two of those lines of apparent weakness which converge in a greatly overflown district in the north of Ireland. One of these lines runs along the inner Heb- rides nearly south and north, and includes in its area, as distinct centres of Plutonic action, the islands of Skye and of Mull, with what are known as the Small Isles lying between, and the promontory of Ardnamurchan. The other line sweeps across the country from north-eat to south-west, commencing at Dunbar on the east, an ( ter- LECTURES ON GEOLOGY. 147 minating, in Scotland, with Arran and Campbelton on the west ; but running, as I have said, across the Irish Sea, it reappears in Ulster. It includes, among many lesser trap eminences, the Campsie, the Ochil, and the Lomond hills; the eminences also on which the castles of Stirling and Dumbarton are built; the hills which give character to the scenery around Edinburgh, Corstorphine, Blackford, the Pentlands, the Castle rock, the Calton, Salisbury Crags, and Arthur's Seat ; and far to the east, that Haddington gioup of trap hills to which North Berwick Law, the Bass, and the Isle of May belong. Beyond these great lines of injected Cracks and filled-up craters, especially to the north and east, there are wide districts in Scotland in which there does not occur a single trap rock. The lava- like flood found its way to the surface from the fiery depths beneath, through the chinks and crannies which we now find indicated by the dikes and insulated stacks and hills of what we may term the Lothian and Hebridean lines, and through these only; and those portions of the Low- lands of Scotland which lie to the north of the Grampians, such as the plains of Caithness, Moray, and Easter Ross, present, from the absence of the trap, an entirely different character from that exhibited by the Lowlands of the South. The igneous rocks have been divided, according to their mineral or mechanical character, into tuffs, amygdaloids, porphyries, dolerites, claystones, clinkstones, wackes, tra- chytes, and various other species. For our present pur- pose, however, and as adequate to the demands of our necessarily brief and imperfect sketch, we may regard the trap rocks as consisting of but two great divisions, first, the traps proper, including all igneous masses, from the porphyries to the basalts, which were ejected from the 148 LECTURES ON GEOLOGY. abyss in a molten form, and which either overflowed from their vents and craters certain portions of the earth's sur- face, whether subaqueous or subaerial, or, forcing their way between strata of the sedimentary rocks, formed among them dikes, or beds, or pillar-like masses; and secondly, trap-tuffs, which, though igneous in their components, were ejected from craters in the form of loose ashes and de- tached fragments, or were ground down by the agency of water, and subsequently arranged in regular strata under the same laws which have given their stratification to the rocks of aqueous origin amid which we so frequently find these trap-tuffs intercalated. You will at otite see that the division here is a natural one. There is a wide differ- ence betwixt a stratum of broken glass and scorias, the debris of a glass-house arranged by the tide on the beach on which it had been cast down a few hours before, and a continuous sheet of plate-glass still retaining its place in the mould into which it had been run off by sluices from the furnace. And such is the difference between trap-tuff and trap proper. We have to anive, too, when we find them occurring, as in this neighborhood, among the rocks of a district, at very different conclusions regarding their date and history. Without inquiring whether in some rare instances an eruption of volcanic mud might not possi- bly be ejected, by a sort of hydraulic-press process, between strata of previously existing rock, and thus a tuff-bed come to be formed which was not only newer than the stratum on which it rested, but also than that by which it was overlaid, we may receive it as a general fact, that the true tuff-bed, like beds of the ordinary sedimentary rocks, is more modern than the stratum on which it rests, and more ancM-nt than tin- Mratum which overlies it; that if it oc- cur, for in>taiK-r, among the Old lied Sandstones, it belongs LECTURES ON GEOLOGY. 149 to the age of the Old Red Sandstones ; if among the Coal Measures, to the age of the Coal Measures ; and if among the Oolites, to the age of the Oolites. But we cannot predicate after the same fashion, that the bed of trap proper which we find resting over one series of sediment- ary strata and under another is of nearly the same age as the rock above and below, or just a little older than the upper and a little newer than the nether ones. It may have been injected among them many ages after their deposition, during even an entirely different period of the earth's history. We may safely infer, that those beds of stratified trap-tuff which alternate in the Calton Hill with beds of trap-porphyry belong to the Carboniferous period, and are very considerably older than the overlying sand- stones and shales on which Regent Terrace is built ; but we can no more infer that the great bed of greenstone which forms the picturesque crown of Salisbury Crags is of the same age as the rocks among which it occurs, or, more strictly, a little newer than the strata below and a little older than the strata above, than we can infer that a cast-iron wheel or axle is of the same age as the mould into which it was run, or, more strictly, a little newer than the bottom of the mould, and a little older than the top of it. 1 Let us now devote a brief space to the consideration of 1 The usual test of the age of these melted traps is the relation they bear to the rocks which overlie them. If the part of the superjacent bed resting on the igneous rock present an altered appearance, as if it had been more or less baked in a furnace, the trap is regarded as intrusive, that is, it forced its way between the planes of the strata, and must conse- quently be of later age. If, on the other hand, the beds above display no symptom of alteration, and more especially if they consist of trap-tuff, the underlying igneous rock may be presumed to have been erupted either under water or in open air, as the case may be : and hence it is regarded as in a general way contemporaneous with the strata among which it occurs G. 13* 150 LECTURES ON GEOLOGY. the scenery usually associated with the trap rocks, a subject which should possess some little interest to an Edinburgh audience, seeing that their most magnificent of cities owes almost all that is imposing and peculiar in its aspect and appearance to this cause. The scenery of a trap district may be resolved into two components. In an ancient ruin we frequently see stones hollowed by decay into a sort of fantastic fretwork, not very unlike that which roughens some of our more ancient runic obelisks; and we recognize as the cause of these irregularities of surface on which the effect depends, certain original ine- qualities in the texture of the mass, and certain weather- ing influences, which, while they w r ore away the softer por- tions, spared such as were harder and more durable. And such, on a larger scale, are the two elements operative in the production of the peculiarities of trap scenery. The hard trap rocks injected into the comparatively soft sand- stones and shales of a distiict, such as that which sur- rounds the Scottish capital, compose a mass of very various texture and solidity, which, if operated upon equally by some power analogous to the weathering one in the case of the fretted stone, would necessarily yield unequally ; and the weathering influences we find represented on the large scale by the denuding agencies. The noble eminen- ces which give character and individuality to our city were literally scooped out of the general mass by tides, and waves, and deep-acting currents, as the sculptor chis- els out his figures, in executing some piece in alto relievo, by chipping away the surrounding plane. The bold figure of the poet Hogg becomes almost a literality here : " Who was it scooped these stony waves? Who scalp'U the brows of old Cairngorm, Am! dny: t] lcs p evcr-yawiiiri'j; caves? 'Twas I, the spirit of the storm." LECTURES ON GEOLOGY. 151 The masses of enclosed trap are of various forms. Some- times they occur as deeply-based pillar-like masses, filling up, it is possible, ancient craters. The rock of hard clink- stone on which the Castle of Edinburgh stands is one of these ; but the long-inclined plane of sedimentary deposits which it shielded from the wear of the western current interferes with its column-like outline. The Bass rock is an example of the same kind, with no sedimentary tail to mar the effect of its natural outline. The dike is another and yet more characteristic form of trap rock : it is a rock that was moulded in a longitudinal crack or rent, as the other was moulded in a well-like crater ; and when the original matrix in which it was cast has been washed from its sides, and it remains standing up over the level, it assumes the wall-like or c&'&e-like form to which it owes its name. In sailing along the west coast of Scotland in a clear sunny day, that gives to each projecting crag its deep patch of shadow, these fragments of walls, of vastly more ancient date than the oldest and most venerable of our Scottish ruins, may be seen rising from the beach along the faces of grassy banks or rounded tuft-formed precipices, and communicating to the general scenery one of its most characteristic features. But one of the main scenic peculiarities of the trap districts is derivable from their trap beds. We find in this neighborhood, among the hills of the Queen's Park, bed rolled over bed, with bands of shale, or sandstone, or soft trap-tuff, between; and these beds, ranged often in nearly parallel lines, and bared by the denuding agencies, present not unfrequently, seen in profile, the appearance of a flight of steps. Hence the generic name for this class of rocks, trappa, a stair : the traps are the stair-like rocks. As seen in a calm, clear morning, from nearly the eastern termination of Regent 152 LECTURES ON GEOLOGY. Terrace, the Arthur Seat group of hills exhibits three of these beds ranged for considerable distances in nearly parallel lines, and, with these, well-marked fragments of several others. First, reckoning from the west or south, there is the continuous greenstone bed of Salisbury crags ; next, the partially-broken bed of greenstone porphyry known as the Bay Crag; next, the continuous bed of compact greenstone known as the Hill Crag, that along the top of which the path ascends to the summit of Arthur Seat from St. Anthony's Well ; and then there are at least two beds of basalt, partially sanded over, which rise in interrupted steps along the face of the eastern hill. These beds fbrm the peculiar feature of the fine fragment of land- scape which from this point of view the Arthur Seat group of hills composes. 1 The trap scenery may be described generally as eminently picturesque. From the circum- stance that its eruptive masses rise often from amid level fields, and that its hard abrupt beds, dikes, and columns, alternate often with rich, soft strata, that decompose into fertile soils, it abounds in striking contrasts. The soft plain ascends often at one stride into a hill fantastically rugged and abrupt ; and bare and fractured precipices overtop terraced slopes or level platforms, rich in verdurg. Some of the more famed scenery of England owes its beauty to the trap rocks. Hagley, the seat of the Lyttle- tons, so celebrated in the English poetry of the last cen- tury for its beauty, is situated half on a range of pictur- esque trap hills, half on a level plain of the New Red Sandstone; and the far-famed view from the Leasowes 1 ( >ti the west coast of Mull, and the islands of Gometra and Ulva, six or eight of these step-like beds may he seen, rising the one over the mliiT, like terraces or stories in a building; and the whole landscape seems barred with right lines, that in this district lie neurly parallel to the horizon. LECTURES ON GEOLOGY. 153 owes much of its beauty to the traps of the Clent Hills. But it would be unpardonable, in treating, however slightly, of the scenery of the trap, to omit all refer- ence to one of its strangest features, those of ranges of polygonal columns which, in at least the more perfect specimens are peculiar to it, and which impart to dame Nature, in so many instances, those qualities of propor- tion and regularity in which art alone can pretend to vie with or surpass her. The specimens in our own neighborhood are either of small extent, as in Samson's Ribs, or both that and of imperfect form, as at St. An- thony's Chapel and in the adjacent hill-front; but I have seen in the neighborhood of Linlithgow a range of slender columns sufficiently regular to have given rise to a tra- ditional myth in the locality, that they owe their origin to the ingenuity of the old Picts; and the columned scuir of Eigg greatly surpasses in grandeur the far-famed Giants' Causeway, and scarce falls short of it in the sym- metry of its strange architecture. To that wondrous ocean cave of the west which an enlightened age con- tinues to recognize as one of the marvels of Scotland, I need but refer in the graphic verse which the Ettrick Shepherd has transferred, in his "Queen's Wake," to "Allan Bawn, the bard of Mull." " Awed to deep silence, they tread the strand, Where furnaced pillars in order stand; All framed of the liquid burning levin, And bent like the bow that spans the heaven; Or upright ranged, in wondrous array, With purple of green o'er the darksome gray. The solemn rows in that ocean den Were dimly seen like the forms of men; Like giant monks in ages agone, Whom the god of the ocean had sear'd to stone ; And their path was on wondrous pavement old, In blocks all cast in some giant mould." 154 LECTURES ON GEOLOGY. The old scenery of the trap rocks of Scotland, the scenery associated with them when our country, along at least its two great lines of trappean eruption, was a Terra del Fuego, a land of fire, it would require some of that poetic faculty to restore which I would fain challenge for the geologist. Even in the immediate neighborhood of the capital, the rocky crust of the earth has been heaved into vast waves by the imprisoned Plutonic agen- cies struggling for vent; huge floods of molten matter, now hardened into mountain masses, have been injected with earthquake throes between the folds of the stony strata; and a submarine volcano has darkened the heavens with its ashes, shutting out during the day the light of the sun, and throwing its red gleam, when the night had fallen, over the steaming eddies of a boiling and broken sea. The area which we now occupy has heaved like the deck of a storm-beset vessel; the solid earth has been rent asunder; and through the wide cracks and fissures, now existing as greenstone dikes, the red molten matter has come rushing through. Could we this evening ascend into the remote past, when that picturesque eminence which overlooks Edinburgh, according to the poet Malcolm, " Arthur's craggy bulk, That dweller of the air, abrupt and lone," was, like the son of Semele, first ushered into the world amid smoke and flame, you would find the scene such as poets might well desire to contemplate, or solicit the aid of their muse adequately to describe. For many ages, \vliat now exists as the picturesque tract of hill and valley attached to old Holyrood, and to which the privileges of the court still extend, had existed as a tract of shallow sea, darkened, when the tide fell, by algae-covered rocks LECTURES ON GEOLOGY. 155 and banks, and much beaten by waves. From time im- memorial has the portion of the earth's crust which under- lies that shallow sea been a scene of deep-seated igneous action. Vast beds of trappean rock greenstone, and columnar basalt, and amygdaloidal porphyry have been wedged from beneath, as molten injections, between the old sedimentary strata; vast waves of translation have come rolling onwards from that disturbed centre, as some submarine hill, elevated by the force of the fiery injection as the platform of a hydraulic press is elevated when the pump is plied has raised its broad back over the tide, only, however, to yield piecemeal to the denuding currents and the storm-raised surf of centuries. And now, for day after day has there been a succession of earthquake shocks, that, as the plutonic paroxysm in- creases in intensity, become stronger and more frequent, and the mountain waves roll outwards in ever-widening circles, to rise and fall in distant and solitary seas, or to break in long lines of foam on nameless islands un- known to the geographer. And over the roar of waves or the rush of tides we may hear the growlings of a subter- ranean thunder, that now dies away in low, deep mutter- ings, and now, ere some fresh earthquake-shock tempests the sea, bellows wildly from the abyss. The billows . fall back in boiling eddies; the solid strata are upheaved into a flat dome, crusted with corals and shells ; it cracks, it severs, a dark gulf yawns suddenly in the midst; a dense, strongly variegated cloud of mingled smoke and steam arises black as midnight in its central volumes, but chequered, where the boiling waves hiss at its edge, with wreaths of white ; and anon with the noise of many waters, a broad sheet of flame rushes upwards a thousand fathoms into the sky. Vast masses of molten rock, that 156 LECTURES ON GEOLOGY. glow red amid even the light of day, are hurled into the air, and then, with hollow sound, fall back into the chasm, or, descending hissing amid the vexed waters, fling high the hot spray, and send the cross circlets of wave which they raise athwart the heavings of the huger billows pro- pelled from the disturbed centre within. The crater rises as the thick showers of ashes descend; and amid the rending of rocks, the roaring of flames, the dashings of waves, the hissings of submerged lava, and the hollow grumblings of the abyss, the darkness of a starless night descends upon the deep. Anon, and we are startled by the shock of yet another and more terrible earthquake ; yet another column of flame rushes into the sky, casting a lurid illumination on the thick rolling reek and the pitchy heavings of the wave; seen but for a moment, we may mark the silvery glitter of scales, for there is a shoal of dead fish floating past; and as the coruscations of an electric lightning darts in a thousand fiery tongues from the cloud, some startled monster of the deep bellows in terror from the dank sea beyond. Let us raise the curtain once more from over the past of the trap districts of Scotland. Myriads of ages have come and gone ; the submarine volcano has been long extinguished ; and the land, elevated high over the waters, has become a scene of human habitation. But the wild country, marked by the well-known features of abrupt precipitous hill and deep retiring valley, is roughened by many a shaggy wood, and gleams with many a blue lochan, and even its richer plains are but partially broken up by the plough. And lo ! the trappean centres of the district are scenes of fierce war, as of old ; but it is not the dead uninformed elements, fire, earth, and water, but energetic, impassioned man, that now contends, and LECTURES ON GEOLOGY. 157 in fierce warfare battles, with his kind. Yonder, on its trap rock, once the crater of a volcano, is the fortress of the Bass, the stronghold that last surrendered in Britain to William of Nassau; and yonder, on its trap rock, the castle of Dunbar, that brave black Agnes held out in so determined a spirit against the English ; and yonder, on its trap rock, the castle of Dirleton, which stood siege in behalf of our country against Edward I. ; and yonder, on its trap rock, scaled by Lord Randolph of old when he warred for the Bruce, is the castle of Edinburgh, the scene of a hundred fights, and surrounded by the halo of a thousand historic associations; and yonder, on its trap rock, is the castle of Stirling, with the battle-ground of Scotland at its feet, and to maintain which against the greatest of our Scottish kings, the second Edward vainly fought the battle of Bannockburn ; and yonder, on its trap rock, is the castle of Dumbarton, long impregna- ble, but which the soldier of the Reformation won at such fearful risk from the partisans of Mary. I remember at one time deeming it not a little curious that the early geological history of a country should often, as in this instance, seem typical of its subsequent civil history. If a country's geologic history had been very disturbed, if the trap rock had broken out from below, and tilted up its strata in a thousand abrupt angles, steep precipices, and yawning chasms, I found the chances as ten to one that there succeeded, when man came upon the scene, a his- tory, scarce less disturbed, of fierce Wai's, protracted sieges, and desperate battles. The stormy morning during which merely the angry elements had contended, I found suc- ceeded in almost every instance by a stormy day, mad- dened by the turmoil of human passion. But a little re-: flection dissipated the mystery ; though it served to show 14 158 LECTURES ON GEOLOGY. through what immense periods mere physical causes may continue to operate with moral effect, and how, in the purposes of Him who saw the end from the beginning, a scene of fiery confusion of roaring waves and heaving earthquakes, of ascending hills and deepening valleys may have been closely associated with the right develop- ment and ultimate dignity and happiness of the moral agent of creation, unborn at the time, reasoning, re- sponsible man. It is amid these centres of geologic dis- turbance, the natural strongholds of the earth, that the true battles of the race, the battles of civilization and civil liberty, have been successfully maintained by handfuls of hardy men, against the despot-led myriads of the plains. In glancing over a map of Europe and the countries adjacent, on which the mountain groups are marked, you will at once perceive that Greece and the Holy Land, Scotland and the Swiss cantons, formed centres of great plutonic disturbance of this character. They had each their geologic tremors and perturbations, their pro- tracted periods of eruption and earthquake, long ere their analogous civil history, with its ages of convulsion and revolution, in which man was the agent, had yet com- menced its course. And, indirectly at least, the disturbed civil history was in each instance a consequence of the disturbed geologic one. From the Tertiary deposits we pass direct to the few scattered remains which survive in Scotland of the Cre- taceous period. It is now nearly thirty years since it was found by geologists that chalk flints inclosing in many specimens the peculiar organisms of the system, occur in the superficial deposits of Banff and Aberdeenshires ; and about three years ago they were also discovered by a very ingenious man, a Thurso tradesman, Mr. Robert Dick, in LECTURES ON GEOLOGY. 159 the boulder-clays of Caithness. It is, however, a curious fact, that what the geologist has only come to know within the course of the present generation was well known to the wild aboriginal inhabitants of the country some three or four thousand years ago. Well-nigh one half the ancient arrow and smaller javelin heads of the stone- period in Scotland, especially those found to the north of the Grampians, were fashioned out of the yellow Aber- deenshire flints. A history of those arts of savage life which the course of discovery served to supplant and obliterate, but which could not be carried on without a knowledge of substances and qualities afterwards lost, until re-discovered by scientific curiosity, would form an exceedingly curious one. On finding, a good many years ago, a vein of a bituminous jet in one of the ichthyolite beds of the Old Red Sandstone of Ross, beds unknown at the time to even our first geologists, it curiously impressed me to remember that my discovery was, after all, only a discovery at second-hand ; for that in an un- glazed hand-made urn of apparently a very early period, dug up in the neighborhood only a few years before, there had been found a very primitive necklace, fashioned out of evidently the same jet. It would seem that to these ichthyolite beds, unknown at the time in the distnct to all but myself, the savage inhabitants had had recourse for the materials for their rude ornaments thousands of years before. They were mineralogists enough, too, as their stone hatchets and battle-axes testify, to know where the best tool and weapon-making rocks occur ; and I once found in a northern locality a battle-axe of an exceeding strong and tough variety of indurated talc, that nearly approached in character to the axe-stone of Werner, which, if native to Scotland at all, is so in some primary district 160 LECTURES ON GEOLOGY. which I am not mineralogist enough to indicate. It shows us after how strange a fashion extremes may meet, that rude savages, ignorant of the use of the metals, and the scientific explorers of a highly civilized age, rationally desirous to know how the adorable Creator wrought upon this earth of old, ere man had yet entered upon it as a scene of probation, should have formed an acquaintance with the same class of objects, classes of objects of which the men of an intervening period knew nothing. The chalk fragments and flints of Caithness and Banff seem to have been earned eastward on the occidental current of the Pleistocene period, those of the one county from that western portion of the chalk ring or girdle to which I have already referred as lying in the Atlantic, and those of the other from that eastern portion of the ring which is buried in the outer reaches of the Moray Frith. In Aberdeenshire, however, some twenty miles or so to the north of the city, in the parish of Ellon and some of the contiguous parishes, and running at a considerable distance inland in a line nearly parallel to the coast, the flints so abound, and, unlike those of the English gravels, are so little water- worn as to give evi- dence that they must have been derived from the disinte- gration of outliers of the system that once existed, it is probable, in their immediate neighborhood. They over- lie, too, in some parts of this locality, what seems to be a re-formation of the greensand ; of which the soft, inco- herent masses, containing, as they do, in some, in a good state of keeping, some of the more fragile organisms of the deposit, could not possibly have travelled far. The ill <-f our chalk flints and of the underlying greensnnd ire sufficiently numerous and characteristic to serve the LECTURES ON GEOLOGY. 161 purpose of identifying the worn and scattered deposits in which they occur with the amply developed chalks and greensands of England, but perhaps not sufficiently so, nor yet always in a sufficiently fine state of preservation, to render the district a very hopeful scene of labor to the col- lector desirous absolutely to extend our knowledge of the extinct forms of life. I have seen, however, especially in the collections of Dr. Fleming, the Rev. Mr. Longmuir, of Aberdeen, and Mr. Fergusson, of Glasgow, fine and very characteristic specimens of the Scotch Chalk, delicate flustra sponges and corals locked up in flint, well- marked portions of the sea-egg order (Echinidae) belong- ing to the cidarite, galerite, and spatangus families, terebratulae of various species, good specimens of that very characteristic conchifer of the Chalk, the Inoceramus, with casts of minute belemnites and portions of ammo- nites and baculites. The group of remains preserved is unequivocally that of the Cretaceous fauna, just as Scot- land has also a group of archaeological remains decidedly Roman ; though in cither case these remains serve but for purposes of identification with larger groups elsewhere : and in order thoroughly to study either the one or the other, the antiquary or geologist would have to remove from what is equally the outskirts of the old Roman or old Cretaceous empire, towards its centre in the south. All our geologists agree in holding that the Chalk was deposited in an ocean of very considerable depth, and of such extent that it must have covered for many ages the greater part of what is now southern and central Europe. It has been traced in one direction from the north of Ire- land to the Crimea in Southern Russia, a distance of about twelve hundred miles ; and in another direction from the south of Sweden to the southwest of. France, a distance of 14* 162 LECTURES OX GEOLOGY. about nine hundred miles ; and there are extensive districts both in France and England where it attains to an average thickness of not less than a thousand feet. The only anal- ogous deposit of the present time occurs on comparatively a small scale among the coralline reefs and lagoons of the Pacific, where there is in the act of forming an impalpable white mud derived from the corals, which in dried speci- mens cannot be distinguished by the unassisted eye from masses of soft chalk. But what chiefly distinguishes the true chalk from any of its modern representatives is the amazing number of microscopic animals which it contains. On a low estimate, half its entire bulk is composed of animalculites of such amazing minuteness, that it has been calculated by Ehrenberg that each cubic inch of chalk may contain upwards of a million of the shells of these crea- tuivs. The chalk rocks so characteristic of the sister king- dom have been often sung by the poets as " Rising like white ramparts all along The blue sea's border." And, in especial, one " chalky bourn of dread and dizzy summit " has been made by the greatest of poets the sub- ject of the sublimest description of a giddy, awe-inspiring precipice ever drawn. And here is there a new associa- tion with which to connect the chalk cliffs of England. Every fragment of these cliffs was once associated with animal life; that impalpable white dust which gives a milky hue to the waves as they dash against them, consists of curiously organized skeletons ; even the white line which I draw along the board, were our eyes to be suddenly endowed with a high microscopic power, would resem- ble part of the wall of a grotto covered over with shells. And, embedded in this mass of minute, nicely-framed LECTURES ON GEOLOGY. 163 invisibilities, Polythalamia, Foraminifera, Polyporia, and Diatoraaceae, we find fossils of larger size, such as >Spa- tangus-cor and the spiny Plagiostoma, which seem to have found proper habitats in the mud formed by the dead remains of these animalculae. Curious examples of a similar kind may be still seen among the Hebrides, of sand-burrowing molluscs and echinoderms finding habitats amid accumulations of the debris of organic life, chiefly comminuted shells, on coasts where otherwise there could have been no place for them. The deep-sea shells pro- pelled shorewards by the agency of tides and waves are ground down by the action of the surf against the rocks. They may be seen occurring in the hollows of the skerries, as one passes shorewards along some of the rocky bays, in handfuls of more and more comminuted fragments, just as, in passing along the successive vats of a paper-mill, one finds the linen rags more and more disintegrated by the cylinders ; and then, within some sheltering shelf or ledge, we find the gathered handfuls of former ages spreading into a wave-rippled beach of minute shelly particles, that presents, save in its snow-white color, the appearance of sandy beaches of the ordinary mineral components. But the beach once formed in this way soon begins to receife accessions from the exuvia? of animals that love such localities, spatangi, razor-fish, cockles, and the several varieties of the gaper family, and that enjoy life agree- ably to their natures and constitutions, not the least sad- dened by the idea that they are living amid the rubbish of a charnel-house ; and sometimes one-half the whole beach comes thus to be composed of a class of remains that, save for the previous existence of the other half of it, could not have been formed in such localities at all. Now, such must have been the state of matters in the times of the 1G4 LECTURES ON GEOLOGY. Chalk. Unnumbered millions must have died in order that the medium might be provided in which a class of their successors could alone live. Of the land which skirted this ocean of the Chalk, or of its productions, we know almost nothing. There have been found in Chalk flints a few fragments of silicified wood, and, in one or two instances, the cones of cycadaceous plants; and the upper beds of the system have furnished the remains of a gigan- tic lizard, the Mosasaurus, with those of turtles, tor- toises, and Pterodactyls. True, the Mosasaurus may have been, as Cuvier supposed, a marine reptile, and the turtles must have been so ; but then both, as egg-bearing animals, must have brought forth their young on some shore ; and the tortoises, with the Pterodactyl or flying lizard, must be regarded as decidedly terrestrial. Such is almost all we yet know of the flora or fauna of the land of the Chalk ; whereas in marine organisms the system is so exceedingly rich, that its ascertained species amount, we find it stated by Brown, to about three thousand. The geologic dio- rama abounds in strange contrasts. When the curtain last rose upon our country, we looked abroad over the amber- producing forests of the Tertiary period, with their sunlit glades and brown and bosky recesses, and we saw, far dis- tant on the skirts of the densely wooded land, a fire-belch- ing volcano, over-canopied by its cloud of smoke and ashes. And now, when the curtain again rises, we see the same tract occupied, far as the eye can reach, by a broad ocean, traversed by a pale milky line, that wends its dimpling way through the blue expanse, like a river through a meadow. That milky way of turbid water indicates the course of a deep-setting current, that disturbs, far beneath, the impalpable mud of the Chalk. Sailing molluscs career in their galleys of pearl over the surface of this ancient LECTURES ON GEOLOGY. 165 sea ; fishes of long extinct species dart with sudden gleam through its middle depths; and far below, on its white floor, the sea urchin creeps, and the spatangus burrows, and crania and terebratulae have cast anchor, and the Crista Galli (or carinated oyster) opens its curiously plicated valves, carved with the zigzag mouldings of a Norman doorway, and the flower-like marsupite expands its living petals. And, dim and distant in the direction of the future Grampians, we may espy a cloud-enveloped island ; but such is its remoteness, and such the enveloping haze, that we can know little more than that it bears along its shores and on its middle heights a forest of nameless trees, unchronicled by the fossil botanist. In bringing to a close this part of my subject, let me here remark, that, if we except the obscure and humbly organized diatomaceae, a microscopic family of organ- isms which some of our authorities deem animal and some vegetable, and of which hundreds and thousands would find ample room in a single drop of water, we have now reached a point in the history of our country, in which there existed no species of plant or animal that exists at the present time. Not a reptile, fish, mollusc, or zoophyte of the Cretaceous system continues to live. We know that it is appointed for all individuals once to die, whatever their tribe or family, because hitherto all indi- viduals have died ; and Geology, by extending our expe- rience, shows us that the same fate awaits on species as on the individuals that compose them. In the one case, too, as in the other, death has its special laws; but the laws which determine the life and death of species seem widely different from those which regulate the life and death of individuals and generations. In general, and with but a few exceptions in favor of the cold-blooded division of the 1C(3 LECTURES ON GEOLOGY. vertebrata, the higher order of animals live longest. A man may' survive for a hundred years; an ephemera bursts from its shell in the morning, and dies at night. But it is far otherwise with the higher orders of species. Molluscs and corals outlive the vertebrata ; and tribes of the low infusory animals outlive molluscs and corals. We know not that a single shell of at least the latter Pleis- tocene period has become extinct ; but many of its noblest quadrupeds, such as the Irish elk, the cave-bear, tiger, and hyena, and the northern rhinoceros, hippopotamus, and elephant, exist no longer. And as we rise into the remote past, and take farewell, one after one, of even the lower forms, shells and corals, and get into a formation all of whose visible organisms are old-fashioned and extinct, we apply the microscope to its impalpable dust, and again, among still humbler and lowlier shapes, find ourselves in the presence of the familiar and the recent. In another sense than that which the old poet contemplated, we learn from the history of species that the most lowly are the most safe. " The tallest pines feel most the- power Of wintry blasts : the loftiest tower Comes heaviest to the ground. The bolts that spare the mountain side His cloud-cap't eminence divide, And spread the ruin round." How long some of these extinct species may have lived we know not, and may never know ; but in all cases their term of existence must have been very extended. Even the extinct elephant lived long enough as a species to whiten the plains of Siberia with huge bones, and to form quarries of ivory that have furaished the ivory market for year after year with its largest supplies. And of some of the humbler species of animals, the period during which LECTURES ON GEOLOGY. 167 they have continued to live must have been vastly more protracted. Cyprina Islandica seems to have come into existence at least as early as the fossil elephant ; and now, thousands of years after the boreal pachyderm is gone, the boreal shell still exists by millions, and evinces no symp- tom of decline. And yet, since the commencement of the great Tertiary division, series of shells, as hardy, appar- ently, as Cyprina, have in succession come into being, and then ceased to be. The period over which we have passed includes generations of species. But there was space enough for them all in the bygone eternity. It has some- times appeared to me as if, from our own weak inability to conceive of the upper reaches of that awful tide of continuity which had no beginning, and of which the measured shreds and fragments constitute time, we had become jealous lest even God Himself should have wrought in it during other than a brief and limited space, with which our small faculties could easily grapple. " Oh, who can strive To comprehend the vast, the awful truth Of the eternity that hath gone by, And not recoil from the dismaying sense Of human impotence! The life of man Is summed in birthdays and in sepulchres, But the eternal God had no beginning." There are two great infinites, the infinite in space and the infinite in time. It were well, surely, to be hum- ble enough to acknowledge it accordant to all analogy, that as He who inhabits eternity has filled the one limit- less void that of space with world upon world and system upon system, far beyond the reach of human ken, He should also have wrought in the other limitless world that of time for age after age, and period after period, far beyond the reach of human conception. LECTURE FOURTH. The Continuity of Existence twice broken in Geological History The Three great Geological Divisions representative of three independent Orders of Ex- i-U'iices Origin of the Wealden in England Its great Depth and High Antiquity The question whether the Weald Formation belongs to the Creta- ceous or the Oolitic System determined in favor of the latter by its Position in Scotland Its Organisms, consisting of both Salt and Fresh Water Animals, indicative of its Fluviatilc Origin, but in proximity to the Ocean The Out- liers of the Weald in Morayshire Their Organisms The Sabbath- Stone of the Northumberland Coal Pits Origin of its Name The Framework of Scot- land The Conditions under which it may have been formed The Lias and the Oolite produced by the last great Upheaval of its Northern Mountains The Line of Elevation of the Lowland Counties Localities of the Oolitic Deposits of Scotland Its Flora and Fauna History of one of its Pine Trees Its Animal Organisms A Walk into the Wilds of the Oolite Hills of Sutherland. THE mystic thread, with its three strands of black, white, and gray, spun by the sybil in " Guy Mannering," formed, she said, a "full hank, but not a haill ane:" the lengthened tale of years which it symbolized " was thrice broken and thrice to asp." I have sometimes thought of that wonderfully mingled and variously colored thread of existence which descends from the earliest periods known to the geologist down to our own times, as not unaptly represented by that produced on this occasion from the spindle of the gipsy. "We find, in its general tissue, species interlaced with and laying hold of species, as, in the thread, fibre is interlaced with and lays hold of fibre ; and as by this arrangement the fibres, though not themselves continu- ous, but of very limited length, form a continuous cord, so LECTURES ON GEOLOGY. 169 species of limited duration, that at certain parts in the course of time began to be, and at certain other parts became extinct, form throughout immensely extended periods a continuous cord of existence. New species had come into being ere the old ones dropped away and disap- peared ; and there occurred for long ages no break or hiatus in the course, just as in the human family there occurs no abrupt break or hiatus, from the circumstance that new generations come upon the stage ere the old ones make their final exit. But in the geological thread, as in that of the sybil, the continuity is twice abruptly broken, and the thread itself divided, in consequence, into three parts. It is continuous from the present time up to the commencement of the Tertiary period; and then so abrupt a break occurs, that, with the exception of the microscopic diatoniacea3, to which I last evening referred, and of one shell and one coral, not a single species crosses the gap. On its farther or remoter side, however, where the Secondary division closes, the intermingling of species again begins, and runs on till the commencement of this great Secondary division; and then, just where the Pa- laeozoic division closes, we find another abrupt break, crossed, if crossed at all, for there still exists some doubt on the subject, by but two species of plant. 1 And then, from the farther side of this second gap the thread of being continues unbroken, until we find it terminating with the first beginnings of life upon our planet. Why these strange gaps should occur, why the long descend- ing cord of organic existence should be thus mysteriously broken in three, we know not yet, and never may ; but, 1 For a reference to the research of the last two years, which has been busily at work upon this precise epoch, see Preface. 15 170 LECTURES ON GEOLOGY. like the division into books and chapters of some great work on natural history, such as that of Cuvier or Buffon, it serves to break up the whole according to an intelligible plan, the scheme of which we may, in part at least, aspire to comprehend. The three great divisions of the geol- ogist, Tertiary, Secondary, and Palaeozoic, of which these two chasms, with beginnings of life on the one hand, and the present state of things on the other, form the terminal limits, represent each, if I may so express my- self, an independent dynasty or empire. Under certain qualifications, to which I shall afterwards refer, the Ter- tiary division represents the dynasty of the mammal ; the Secondary division the dynasty of the reptile; and the Palaeozoic division the dynasty of the fish. Each of the divisions, too, has a special type or characteristic fashion of its own ; so that the aspect of its existences differs as much in the group from the aspect of the existences of each of the others, as if they had been groups belonging to different planets. The vegetable and animal organisms of the planet Venus may not differ more from those of the planet Mars, or those of Mars from the organisms of the planet Jupiter, than the existences of the Tertiary division differ from those of the Secondary one, or those of the Sec- ondary one from the existences of the Palaeozoic division. Beneath the two great divisions of the Cretaceous sys- tem, and consequently of more ancient date, there* occurs in the sister kingdom an important series of beds, chiefly of lacustrine or fluviatile origin, known as the Wealden. Before the submergence of what are now the south-eastern parts of England, first beneath the comparatively shallow- sea of the Greensand, and then beneath the profounder depths of the ocean of the Chalk, a mighty river, the drain- age of some unknown continent, seems to have flowed for LECTURES ON GEOLOGY. 171 many ages along these parts of Kent, Surrey, and Sussex, known as the Valley of the Weald. The banks of this old nameless river were covered with forests of coniferous trees of the Pine and Araucarian families, with cycadeae and ferns, and were haunted by gigantic reptiles, herbiv- orous and carnivorous, some of which rivalled in bulk the mammoth and the elephant; its waters were inhabited by amphibiae of the same great class, chiefly crocodiles and chelonians of extinct species and type ; by numerous fishes, too, of the old ganoid order; and by shells whose families, ana even genera, still exist in our pools and rivers, though the species be all gone. Winged reptiles, too, occasionally flitted amid its woods, or sped over its broad bosom ; and insects of the same family as that to which our dragon flies belong spent the first two stages of their existence at the bottom of its pools and shallows, and the terminal one in darting over it on their wings of delicate gauze in quest of their prey. It is stated by Dr. Man tell, our highest author- ity on the subject of the Weald, that the delta of this great river is about two thousand feet in thickness, a thickness which quadruples that of the delta of the Mis- sissippi. There can be little doubt that the American " Father of Waters " is a very ancient river ; and yet it would seem that this river of the Wealden, which has now existed for myriads of ages in but its fossilized remains, hidden under the Wolds of Surrey and Kent, this old river, which flowed over where the ocean of the Oolite once had been, and in turn gave place and was overflowed by the ocean of the Chalk, continued to roll its down- ward waters amid forests as dense and as thickly inhabited as those of the great American valley, during a period per- haps four times as extended. Compared with the English formation of the Weald, 172 LECTURES ON GEOLOGY. which extends over a wide, and what was at one time a very rude district, our beds of the Scotch Wealden are but of little depth, and limited extent. And yet they serve to throw a not unimportant light on the- true character and place of the formation. It occurs in England, as I have said, between two great marine systems, the Cretaceous and the Oolitic; and the question has arisen, to which of these systems does it belong? Now, our Scotch beds of the Weald determine the question. They make their ap- pearance, not at the top of Oolitic deposits, as in England, but intercalated throughout the system, occurring in the Isle of Skye, where they were first detected many years ago by Sir Roderick Murchison, immediately under the Oxford clay, a bed of the Middle Oolite ; and at Brora, win -re they were first detected a few twelvemonths since by Mr. Robertson of Elgin, in pretty nearly the same me- dial position, and where what is known as the great Oolite occurs. Three years ago I had the pleasure of detecting a bed of the same lacustrine or estuary character, and bearing many of the characteristic marks of the Weald, greatly lower still, lower, indeed, than any fresh-water deposit of the Secondary division in Britain. I found it occurring not forty yards over the bottom of the Lias, the formation which constitutes the base of the Oolitic system. In Morayshire the Weald occurs in the form of outliers, that rise, as at Linksfield, in the immediate neighborhood of Elgin, into low swelling hills, resting on the Old Red Sandstone of the district, and so thoroughly insulated from every other rook of the same age, that they have reminded me of detached hillocks of debris and ashes shot down on the surface of some ancient moor by some painstaking farmer, who had contemplated bringing the wa>te tinder subjection to the plough. But though value- LECTURES ON GEOLOGY. 173 less, from their detached character, for determining the place of the formation, they serve better than the inter- calated beds of Ross, Skye, and Sutherland, to establish by their animal remains the palaeontological identity of the Scotch with the English Wealden. Rather more than twelve years ago, the late Dr. John Malcolmson, of Madras, a zealous and accomplished ge- ologist, too early lost to science and his friends, brought with him, when on a visit to the Continent, several speci- mens of ichthyic remains from a Morayshire deposit, and submitted them to Agassiz. "Permit me," said the natur- alist, " to find out for myself the formation to which they belong." He passed hand and eye over tooth and spine, plate and bone, and at length set his finger on a single scale of rhomboid al form and brightly enamelled surface. " Some of these teeth," he said, " belong to the genus Hybo- dus, but the species are new, and the genus itself has a wide range. Here, however, is something more determinate. This scale belongs to the Lepidotus minor, or ichthyolite of the Weald, and one of the most Characteristic fishes of the great fresh-water formation of Surrey and Kent." The fossils on which the distinguished ichthyologist thus promptly, and, as it proved, correctly decided, had been collected by Mr. Malcolmson from the Wealden outlier at Linksfield ; and the ichthyolite which he so specially singled out the Lepidotus seems to have been a fresh-water fish of the nearly extinct ganoid order, and more nearly akin to the Lepidosteus of the North Ameri- can rivers and lakes than to any other fish that now exists. By much the greater number of its contemporaries in the deposit also belonged to lakes and rivers. Some of the limestone slabs are thickly covered over by fresh-water shells, of types very much akin to those which still occur 15* 174 LECTURES ON GEOLOGY. in our pools and ditches, such as Planorbis and Palud in a. It presents also beds of a fresh-water mussel akin to a mussel of the English Weald, Mytilus Lyellii ; and it so abounds in the remains of those minute, one-eyed crus- taceans known as the Cyprides, that the vast numbers of their egg-shaped shelly cases give to some of the beds a structure resembling the roe of a fish. It contains, too, bones of a species of tortoise, and several other decidedly fresh-water remains ; while another class of its organisms serve to show that it was occasionally visited by denizens of the sea. It has furnished specimens of bones and teeth of Plesiosaurus, a marine reptile ; and some of the upper beds contain a small oyster; while a class of its remains, the teeth and huge dorsal spines of Hybodonts, an ex- tinct family of sharks, though they may have been fitted to sustain life in brackish water, seem to indicate rather a sea than a lacustrine or river habitat. The deposit took place in all probability in the upper reaches of an estuary operated upon by the tides, and at one time fresh and at another brackish, artfl where, in a certain debatable tract, the fishes, reptiles, and shells of the river met and mingled with the fishes, reptiles, and shells of the sea. I may men- tion, that in the immediate neighborhood of the fresh-water or Weald beds, intercalated, as in Ross and Sutherland, with the marine deposits of the Lias or Oolite, there al- ways occur beds of a species of shell which, though it ex- hibits internally a peculiar structure of hinge, unlike any other known to the conchologist, bears externally very much the appearance of a my til us or mussel. It seems to have lived in brackish water, and to have marked a tran- sition stage between the marine and lacustrine, the salt and the fresh ; for immediately under or over it, as the case occurs, the explorer is ever sure to find productions of LECTURES ON GEOLOGY. 175 the land or of fresh water, lake or river shells, such as cyclas or paludina, or portions of terrestrial plants, and oc- casionally of fresh- water tortoises. This transition shell is known as the Perna. These notices you will, I am afraid, deem tediously minute ; but they indulge us with at least a glimpse of a portion of what is now our country during an immensely extended period, of which no other record exists. Where some nameless river enters the sea, we de- termine, as through a thick fog, which conceals the line of banks on either hand, that the waters swarm with life, rep- tilian and ichthyic : the glossy scales of the river Lepidotus gleam bright through the depths ; while the shark-like ffybodus from the distant ocean shows above the surface his long dorsal fin, armed with its thorny spine ; and over beds of shells of mingled character, a carnivorous fresh- water tortoise, akin to the fierce Trionyx of the southern parts of North America, meets with the scarce more form- idable sea-born Plesiosaurus. In these Morayshire outliers of the Weald we first find in situ in our country (for we need scarce take into account the Tertiary beds of Mull), fossiliferous deposits that have been converted into solid rock ; and certainly the appear- ance of some of the sections is such as to awaken curiosity. In the section of Linksfield, in the neighborhood of Elgin, though the thickness of the deposit does not exceed forty feet, there occur numerous alternations of argillaceous and calcareous beds, differing from each other in color and quality, and not unfrequently in their fossils also ; and each of which evidently represents a state of things which ob- tained during the period of their deposition, distinct from the preceding and succeeding states. 1 Strata of gray, 1 Fielding, in his "Voyage to Lisbon (1754)," gives an account of an inaccessible bank of mud which stretched at low water between the shore 176 LECTURES ON GEOLOGY. green, blue, and almost black clays, alternate with beds of light green, light brown, gray, and almost black limestones; and such is the effect, when a first section is opened in the deposit, as sometimes happens to facilitate the working of a limestone quarry below, that one is reminded, by the variety and peculiar tone of the colors, of the inlaid work of an old-fashioned cabinet made of the tinted woods which were in such common use about two centimes ago. Some of these bands seem, from their contents, to be of fresh water ; some of marine origin ; one bed nearly four feet in thickness is composed almost exclusively of the shelly coverings of a minute crustacean, Cypris globosa, not half the size of a small pin-head ; one is strewed over with the teeth of sharks ; one with the plates and scales of ganoidal fishes ; in one a small mussel is exceedingly abundant; another contains the shells of Planorbis and Paludina; in this layer we find a small oyster, which must have lived in the sea ; in that, a Cyclas, the inhabitant of a lake ; here the plates of a river tortoise ; there the bones of the marine Plesiosaur. Of all the many-colored strata of which the deposit consists, there is not one which does not speak of that law of change of which the poet, as if in anticipation of the discoveries of modern science, sings so philosophically and well : Of chance exchange, oh! let not man complain, Else shall he never, never cease to wail ; at Ryde and the sea. " Between the shore and the sea," he says, " there is at low water an impassable gulf of deep mud, which can neither be traversed by walking or swimming, so that for near one-half of the twenty- four hours Ryde is inaccessible by friend or foe." The same tract now is occupied by an expanse of firm white sand, which forms excellent bathing -round; but immediately under, at the depth of from eighteen inches to tw.. feet, the mud of Fielding's days is found occurring as a dark-colored impalpable silt. LECTURES OST GEOLOGY. 177 For from the imperial dome, to where the swain Rears the lone cottage in the silent dale, All feel the assault of Fortune's fickle gale ; Art, empire, earth itself, to change are doomed : Earthquakes hare raised to heaven the humble vale, And gulfs the mountain's mighty mass entombed; And where the Atlantic rolls, wide continents have bloomed. Regarded, too, as the record of, if I may so express my- self, a party-colored time, these party-colored layers are of no little interest. There forms in the recesses of the Northumbrian coal-pits a party-colored clay, consisting of grey and black layers, which, from a certain peculiarity to which I shall immediately advert, bears the name of Sab- bath-stone. The springs which ooze into the pits are charged with a fine impalpable pipe-clay, which they deposit in the pools and waters of the deserted workings, and which is of a pale gray color approaching to white. When the miners are at work, however, a light black dust, struck by their tools from the coal, and carried by cur- rents of air into the recesses of the mine, is deposited along with it; and, in consequence, each day's work is marked by a thin black layer in the mass, while each night during which there is a cessation of labor, is repre- sented by a pale layer, which exhibits the color natural to the clay. And when a cross section of the substance thus deposited comes to be made, every week of regular employment is found to be represented by a group of six black streaks closely lined off on a pale ground, and each Sabbath by a broad pale streak interposed between each group, exactly such a space, in short, as a clerk, in keep- ing tally, would leave between his fagots of strokes. In this curious record a holiday takes its place among the working days, like a second Sabbath. " How comes this week to have two Sabbaths?" inquired a gentleman to 178 LECTURES ON GEOLOGY. whom a specimen was shown at one of the pits. "That blank Friday," replied the foreman, " was the day of the races." " And what," said the visitor, " means this large empty space, a full fortnight in breadth and more?" "O, that space," rejoined the foreman, "shows the time of the strike for wages: the men stood out for three weeks, and then gave in." In fine, the Sabbath-stone of the Nor- thumbrian mines is a sort of geologic register of the work done in them, a sort of natural tally, in which the sedi- mentary agent keeps the chalk, and which tells when the miners labor and when they rest, and whether they keep their Sabbaths intact or encroach upon them. One would scarce expect to find of transactions so humble a record in the heart of a stone ; but it may serve to show how very curious that narrative might be, could we but read it aright, which lies couched in the party-colored layers of the Moray shire Wealden. All its many beds, green, black, and gray, argillaceous and calcareous, record the workings of nature, with her alternations of repose, in a time of frequent vicissitude, and amid its annals of chem- ical and mechanical change embody in many an episo- dical little passage its exhibitions of anatomical structure and its anecdotes of animal life. Before passing on to the Oolite, as developed in Scot- land, or rather to our Scotch deposits of the marine Oolite, for what we call our Wealden is, as I have shown, merely an estuary or lacustrine Oolite, let me solicit your attention to a few points illustrative of what may be termed the framework of our country. There are two sets of conditions^ under which land may arise from the ocean. Its hills and plateaus may be formed by the subterranean forces violently thrusting them up, like vast wedges, through the general crust of the earth, and high LECTURES ON GEOLOGY. 179 over the ocean level ; or it may be brought up to the light and air en masse by a general elevation over wide areas of the unbroken crust itself; or land may again sink under these two sets of conditions : it may sink in conse- quence of a breaking up and prostration of its framework to the average level of the crust, of a striking back, if I may so speak, of the protruded wedges; or it may sink in consequence of a general depression over a wide area of the portion of the crust on which its framework is erected. Thus Scotland might disappear under the waves, either by some violent earthquake convulsion that would strike down its hills and table-lands to the general level of the earth's crust, and of consequence wholly destroy its contour; or it might disappear through a gentle sinking of the area that it occupies, which would leave its general contour unchanged. "Were there a depression to take place where it now rises, of but one foot in five hundred over an area a thousand miles square, its highest mountain summits would be buried beneath the sea, and yet the contour of the submerged land would remain almost iden- tically what it is, its hills would retain the same relative elevation over its valleys, and its higher table-lands over its lower plains. Now, in the later ages of its history, in those ages, for instance, in which the ice-laden ocean of the boulder-clay rose high along its hill-sides, and it ex- isted as a wintry archipelago of islands, there seems to have taken place scarce any change in its framework : the depressions through which it sank, and the elevations through which it rose, seem to have been depressions and elevations of area; and, whether under or over the waves, it continued to retain its general contour. The last great change which affected its framework, and gave to it a different profile in relation to the general surface of 180 LECTURES ON GEOLOGY. the globe from that which it had borne in the earlier ages, the change which thrust up its latest-born lines of mountains like wedges through the earth's crust, was a change which took place a little posterior to that period of its history at which I am now arrived. We find that its last lines of hills disturbed and bore up with them deposits of the Lias and of the Oolite, but of no later formations. The gigantic Ben Nevis and his Anakim brethren of the same group were raising their heads and shoulders through the earth's crust, to form the future landmarks of our country, shortly after the period when the river Lepidoids of the Wealden were disporting in the same brackish tract with the Hybodont sharks of its seas, and its fresh-water Chelonians and marine Plesiosauri met and intermingled in the same neutral rocks of es- tuary. The last great paroxysm of upheaval among our Scot- tish mountains seems to have operated in lines that trav- ersed the country diagonally from nearly south-west by south to north-east by north, the line indicated by that of the great Caledonian Valley. We find a northern district of considerable extent ploughed in this direction by the great parallel glens traversed by the Spey, the Findhorn, the Nairn, and the Ness. The northern shore of the Moray Frith, too, with that remarkable line of hills which includes the Sutors of Cromarty, pertains to this system, as also the higher mountain range which rises along the coast of Sutherland, and to which the Ord Hill of Caithness belongs. These lines of hills, wherever they have come in contact as along the shores of the Moray Frith with beds of the Lias and Oolite, have disturbed and tilted up, at a steep angle, their edges. The hill of Eathie, in the neighborhood of Cromarty, a hill of the LECTURES ON GEOLOGY. 181 series in which the two Sutors occur, has at one place borne up the Lower Lias on its flanks at an angle of eighty; and among the rocks of the Northern Sutor there is a tall precipice of the Old Red Sandstone, with an uptilted deposit of the Lias at its base, whose abrupt, dizzy front, once the haunt of the eagle, and still that of the blue hawk, was evidently, ere the elevation of the series, part of the horizontal platform on which the first Liassic stra- tum had been deposited. What was a flat submarine bot- tom then, is a steep ivy-mantled precipice now. Across the long deep valleys and mountain ridges of this last line of upheaval in Scotland, the line to which Ben Nevis, Milfourveny, and the Ord Hill of Caithness belong, and whose period of elevation a high Continental authority, Elie de Beaumont, regards as identical with that of the Mont Pilas and Cote d'Or of France, we find a greatly less continuous, because more interrupted and broken, set of ridges, running in a nearly westerly direction. The friths of Dornoch, Cromarty, and Beauly, with all the bays of Munlochy and Urquhart, Loch Oich and Loch Eil, which all strike westwards across the country from off the great diagonal trench of the Caledonian Valley, indicate the direction of this second and earlier line of upheaval. I say earlier line. The hills of the diagonal Ben Nevis line disturbed and broke up the Oolite, whereas the hills of the transverse, or, as I may term it, Ben Weavis line, disturbed and bore up with them nothing more modern than the Old Red Sandstone. I have described the northern part of the kingdom as consisting of a great Primary nucleus, surrounded by strata, more or less broken, of Old Red Sandstone, Lias, and Oolite. 1 Let 1 To which is to be now added Silurian." 16 182 LECTURES ON GEOLOGY. us now further conceive of that nucleus as a stony field, that had been first ploughed across and fretted into deep furrows and steep mountainous ridges, and then in an after period ploughed diagonally, so as partially to efface the former ploughing, so that only in the direction of the last ploughing do the ridges and furrows remain tolerably entire, let us, I say, conceive of such a ploughed field, and we will have a tolerably adequate conception, so far as it goes, of the framework of at least the northern portion of Scotland. In the southern part of the king- dom there is yet another line of elevation exhibited, whose direction from nearly north-east to south-west we find indicated by the nearly parallel lines in which the greater formations of the Lowland counties, from the clay- states that flank the Grampians, to the Grauwackes of the border districts, sweep across the country. I fear that the homely illustrations which I have to employ in rendering my subject comprehensible, such as wedges struck up- wards from below, a field first ploughed across and then diagonally, may have the effect of so reducing my sub- ject in your minds into a mere model, that, through the necessary reduction, more may be lost in expansiveness of feeling than gained by any substitution of clearness of view. There can be little doubt that in the conceptions of mind, as in the collocations of matter, the portable means the small ; and that Goethe exercised his wonted shrewdness in remarking, that when the ancients spoke of the unmeasurable earth and the illimitable sea, it was with a profounder feeling than any now exercised by the geographer in a time when every school-girl can tell that the world is round. You will, however, remember, that though my illustrations are small, my subject is large ; and such of my audience as have sailed over the profound LECTURES ON GEOLOGY. 183 depths of Loch Ness, depths greatly more profound than those of the German Ocean beyond, and seen those lines of russet mountains, so often capped with cloud, and so often, even at midsummer, streaked with snow, that rise on either hand, and that inclose from sea to sea that mighty trench which the old unsophisticated Highlander learned to distinguish as the great Glen of Albyn, when they call up to memory the noble features of the scene, the long retiring vista on either hand, purple in the far distance, and remember that that vast rectilinear hollow forms but one pf the plough furrows of my illustration, they will see that that with which I am in reality deal- ing is the sublime of nature, and that even the details of my subject, rightly, appreciated, are not suited to lower our conceptions of the wonderful workings of old of Him who, by processes which science is but now aspiring to comprehend, "gathered the waters together into one place, *hat the dry land might appear," and laid the deep-seated foundation of the mighty hills. Let us now pass to the Oolite proper, and its base the Lias, as we find them developed in Scotland. They form hut a comparatively small portion of the surface of the country, not much more, it has been estimated, than sixty square miles; nor can I refer definitely to any marked peculiarity of scenery in the districts in which they occur. The Oolites of Sutherland extend westwards -md southwards from the Ord Hill of Caithness to the village of Golspie, a distance of about sixteen miles ; and' form, under the rugged line of hills against whose flanks they recline, a green narrow strip of low country, that, where not too deeply covered up by debris of the Primary rocks, transported from the interior during the Pleistocene period, is, for its extent, of great agricultural value, and 184 LECTURES ON GEOLOGY. bears on its cultured surface the rich fields and extensive woods of Dunrobin, the stately castle of the old earls of Sutherland. Further to the west and south, along the eastern shores of Crqmarty and Ross, detached patches of the Lias occur, as at Shandwick, at the Northern Sutor of Cromarty, at the Southern Sutor, and at the Hill of Eathie, each patch occurring directly opposite, and lean- ing against, one of the upheaved hills, which, as I have already said, were undoubtedly the agents in raising and bringing it to the surface. The Lias and Oolite also ap- pear on the southern side of the Moray Frith, in the counties of Moray and Banff, but merely as outliers of very limited extent, and sorely broken up or ground down by the denuding Pleistocene agencies. On the western coast of Scotland the Lias may be seen on the mainland at Applecross, and on the sides of Loch Aline, opposite the Sound of Mull ; while in the inner Hebrides, it forms, with the Oolite, though greatly overflown by trap, the base of the larger part of the island of Mull, of two of the Small Isles, Eigg and Muck, of Raza and Scalpa, and of large tracts of the eastern and northern half of Skye. At Broadford, in the latter island, the Lias forms the whole of the rich level islet of Pabba, which, lying as at anchor in its quiet bay, reminds one, from its prevail- ing color and form, of one of the low, green steamboats of the Clyde. Opposite Pabba, the Liassic deposit sweeps across the mainland of Skye from sea to sea, along a flat valley some two or three miles wide ; but while the mi- nute Liassic islet resembles, from the softness of its out- line, an islet of England set down in a hill-enclosed bay of the Scottish Highlands, there is nothing English in the scenic character of the Liassic valley. It is a brown and sombre expanse of marsh and moor, studded by blue, LECTUHES ON GEOLOGY. 185 ilreary lochans, interesting, however, to the botanist, as the habitats of the rare Eriocaulon septangulare. The waste is haunted, too, say the Highlanders, by Ludag, a malignant goblin, not more known elsewhere in Europe than the rare plant that in the last age used to be seen at dusk hopping with immense hops on its one leg, for, unlike every other denizen of the supernatural world, it is not furnished with two, and that, enveloped in rags, and with fierce misery in its hollow eye, has dealt heavy blows, it is said, on the cheeks of benighted travellers. Certainly a more appropriate spectre could scarce be sum- moned to walk at nights over the entombed remains of the old monsters of the Lias than one-legged Ludag, the goblin of the wastes of Broadford. Such, in brief, is a summary of our Oolitic deposits. They occupy, as I have said, but a small portion of the surface of Scotland ; and, though coal has occasionally been wrought in them, and though they furnish in several localities supplies of lime and of building stone, their economic importance is com- paratively small. But a well-filled volume the life- long work of some laborious chronicler may have no economic importance in the lower and humbler sense, and may yet form a valuable record of bygone transac- tions and events suited to delight and instruct throughout all generations. And it is thus with the Oolitic deposits of Scotland. Their innumerable strata, closely written "within and without" in a language in which eveiy character is an organism, form the leaves of a record in which many of the marvellous existences that flourished during what are geologically the middle ages of our coun- try's history are well and wonderfully preserved. -Instead of dissipating your attention by describing at length the fossils of its various deposits, I shall attempt giving you 16* 186 LECTURES ON GEOLOGY. a general idea of the whole under the ordinary division of animal and vegetable, as they have come to my knowl- edge during the researches of at least thirty years. In one of its features Oolitic flora of what is now Scot- land must have resembled its flora in the present, or rather in the past age, ere our native pine-woods had yielded to the axe. Trees of the fir or pine division of the Coniferae, many of them of slow growth and large size, must have formed huge forests in a province of the land of the Oolite Avliich extended from what is now the island of Mull to the Ord Hill of Caithness. The Scuir of Eigg, a subaerial mole of columnar pitchstone, four hundred feet in height, and perched on the ridge of a tall hill, rests on the remains of a prostrated forest, as some of our submarine moles rest on foundations of piles. And of this forest all the trees seem to have consisted of one species, a conifer of the Oolite now known to the fossil botanist as the Pinites EiygensiS) or Eigg pine. Branches and portions of the trunks of a similar pine are not unfrequent in the Lias of Eathie and Ross ; and in shale-beds of the Lower Oolite in the neighborhood of Helmsdale there occur in abun- dance fossil trunks and branches, mingled with cones and the narrow spiky leaflets characteristic of the family. I have reckoned in the transverse section of a Helmsdale pine-trunk about two feet in diameter, more than a hun- dred annual rings. And from the rings and roots of some of the others, its contemporaries, I found that curious insight might be derived respecting the state and condi- tion of vegetable life in the old Scotch woods of the Oolite. In the first place, the annual rings themselves told in,-, w l,. n exposed to transmitted light in the micro- scope, that the winters of that time gave vegetation as decided a check as our winters now. The tender woody LECTURES ON GEOLOGY. 187 cells were first dwarfed and thickened in their formation by the strengthening of the autumnal cold, and then for a season they ceased to form altogether. But then the spring came, and over the hard concentric line drawn by the chill hand of winter they began to form themselves anew in full-sized luxuriance; and thus, year after year, and for century after century, the process went on. Some of these ancient pine-trees grew in rich sheltered hollows, arid acquired bulk so rapidly, that they increased their diameter eight and a half inches in twenty years ; others grew so slowly, that they increased their diameter only two and a half inches in forty years. And it is a curious circumstance, that in both those of slower and of more rapid growth we find alternating groups of broader and narrower annual rings, indicating apparently groups of bet- ter and worse seasons. Lord Bacon remarks in one of his Essays, the Essay on the Vicissitude of Things, that it was a circumstance first observed in the Low Countries (the provinces of the Netherlands), that there were cer- tain meteorological cycles of seasons groups of warmer and groups of colder summers, and of more temperate and of less temperate winters which periodically came round again. And we have seen not very successful attempts made in our own times to measure these cycles, and reduce them to a formula, from which the nature of the coming seasons might be determined beforehand. But there can be little doubt whatever the cause or the order of their occurrence that alternations of groups of colder and warmer, better and worse seasons, do occur ; and it seems more than probable that, in obedience to some occult law, as little understood in the present age as when its opera- tions were first detected in the Netherlands, Scotland had in the times of the Oolite, as certainly as now, its alter 188 LECTURES ON GEOLOGY. nating groups of chill and of genial summers, and of tem- perate and severe winters. And the well-marked rings of its fossil Conifene remain to attest the fact. We can even determine the kind of soil into which a certain proportion of these ancient pines struck root. It was extremely shal- low in some localities, and lay over a hard bottom. We find that some of the fossil stumps shot out their roots horizontally immediately as they entered the earth, and sent down no vertical prolongations of the trunk into the subsoil, an arrangement still common among the roots of trees planted on a shallow stratum of soil resting on a hard bottom. Further, we are still able to ascertain that the hard bottom that underlay the soil in which some of the Oolitic pines of Helmsdale grew was composed of Old Red flagstone, identical in its mineral composition and organic remains with what is now known as Caithness flag- But let us trace the history of a single pine-tree of the Oolite, as indicated by its petrified remains. This gnarled and twisted trunk once anchored its roots amid the cran- nies of a precipice of dark-gray sandstone, that rose over some nameless stream of the Oolite, in what is now the north of Scotland. The rock, which, notwithstanding its dingy color, Avas a deposit of the Lower Old Red Sand- stone, formed a member of the fish-beds of that system, beds that were charged then, as now, with numerous fossils, as strange and obsolete in the creation of the Oolite as in the creation which at present exists. It was a firm, undestnictible stone, covered by a thin, barren soil ; and the twisted rootlets of the pine, rejected and thrown back- wards from its more solid planes, had to penetrate into its narrow fissures for a straitened and meam-e subsistence. O The tree grew but slowly: in considerably more than half LECTURES ON GEOLOGY. 189 a century it had attained to a diameter of little more than ten inches a foot over the soil ; and its bent and twisted form gave evidence of the life of hardship to which it was exposed. It was, in truth, a picturesque rag of a tree, that for the first few feet twisted itself round like an overborne wrestler struggling to escape from under his enemy, and then struck out an abrupt angle, and stretched itself like a bent arm over the stream. It must have resembled, on its bald eminence, that pine-tree of a later time described by Scott, that high above " ash and oak," " Cast anchor in the rifted rock, And o'er the giddy chasm hung His shattered trunk, and frequent flung, Where seemed the cliffs to meet on high, His boughs athwart the narrowed sky." The seasons passed over it : every opening spring gave its fringe of tenderer green to its spiky foliage, and every returning autumn saw it shed its cones into the stream below. Many a delicate fern sprang up and decayed around its gnarled and fantastic root, single-leaved and simple of form, like the Scolopendria of our caverns and rock recesses, or fretted into many a slim pinnate leaflet, like the minute maiden-hair or the graceful lady-fern. Flying reptiles have perched amid its boughs ; the light- winged dragon-fly has darted on wings of gauze through the openings of its lesser twigs ; the tortoise and the lizard have hybernated during the chills of winter amid the hol- lows of its roots; for many years it formed one of the minor features in a wild picturesque scene, on which hu- man eye never looked ; and at length, touched by decay, its upper branches began to wither and bleach white in the winds of heaven; when shaken by a sudden hurricane that came roaring adown the ravine, the mass of rock in 100 LECTURES ON GEOLOGY. which it had been anchored at once gave way, and, bear- ing fast jammed among its roots a fragment of the mass which we still find there, and from which we read a por- tion of its story, it was precipitated into the foaming ton rent. Dancing on the eddies, or lingering amid the pools, or shooting, arrow-like, adown the rapids, it at length finds. its way to the sea; and after sailing over beds of massive coral, the ponderous Isastrea and more delicate Tham- nastrea, and after disturbing the Enaliosaur and Belem- nite in their deep-green haunts, it sinks, saturated with water, into a bed of arenaceous mud, to make its appear- ance, after long ages, in the world of man, a marble mummy of the old Oolite forests, and to be curiously interrogated regarding its character and history. The pines of our Scotch Oolite some of them, as I have shown, or rather as my specimens show, of exceed- ingly slow growth are suggestive of a temperate, if not severe climate. The family of their contempoi'aries, how- ever, to which I must next refer as not less characteristic of the flora of this ancient time than the coniferae them- selves, is now to .be found in a state of nature in only the warmer regions of the earth, and can be studied in this part of the world in but our conservatories and green- houses. It is known to the botanist as the Cycadaceous family ; and at least two of its genera, Cycas and Zamia, we find well represented in the Oolitic deposits of Scot- land. In the Zamia, a cylindrical, squat, scale-covered pedestal is fringed along its upper edge by a ring of long pinnate leaves, that radiate outwards like the spokes of a wheel from the nave; and, placed on the centre of the pedestal, there is, when the plant is in fruit, a handsome cone. The tout ensemble is as if a pine-apple, with the pot in which it grew, and with its leaves arranged like a LECTURES ON GEOLOGY. 191 ruff round its stem, formed altogether but one plant. The Oycas is usually taller than Zamia; the leaves also, of the compound pinnate character, are smaller and more bushy; and it resembles, as a whole, a decapitated palm, with a coronal of fern bound atop, as if to conceal the mutilation. With these Cycadacae there flourished in the marshes of the period plants of a family still widely spread over the various climatal zones, but which now attain to any considerable size only within the tropics. I refer to the Equisetacese, or horsetail family, slim, cone-crowned plants, fringed with green verticillate leaves, or branches rather, and which in this country are rarely thicker than a quill, or rarely exceed eighteen inches in height, but which have been found in the intertropical swamps of South America fifteen feet high, and three inches in circumfer- ence at the lower part of the stem. In the Oolite of Scotland, a well-marked, long-extinct species, the JEquise- tuni columnare must have attained, judging from the thickness of the stem, which is sometimes full three inches in diameter, to at least thrice the size of its tropical con. genera. As shown by its remains, which occur in the lignite shales of Brora, it must have been a plant of con- siderable elegance of form, encircled at each joint in some of the specimens by torus-like mouldings grooved cross- wise, traversed in the spaces between by longitudinal markings, delicately punctulated, and gracefully feathered from root to pointed top by its verticillate garlands of spiky leaves. The Lycopodiaceas or club-moss family, existing in rather massier and more aboraceous forms than now, though reduced in a greatly more than equal degree from their gigantic congeners of the Coal Measures, were also abundant (as shown by the rocks of Helmsdale) in the Oolitic flora of Scotland ; and with these there min- 192 LECTURES ON GEOLOGY. uK'd various genera, consisting of numerous species of' Avell-marked ferns. Ferns, indeed, so far as we yet know, may be regarded as forming the base, and pines the apex, of the terrestrial Oolitic flora; and between these two extremes most of its other productions seem to have ranged. The Cycadacese possess certain characters which belong to both : they are, if I may so speak, fern-pines, with, in some instances, a peculiarity of aspect which seems also to ally them to the palms. Again, the Lyco- podiaccae, intermediate between the mosses and the ferns, may be described as fern-mosses, with a peculiarity of aspect in some of the Oolitic species that seems to ally them to the pines. And the Equisetaceaa belongs to at least the same sub-class as the ferns, the Acrogens. The Palmar, as shown by the English deposits, were also present in the Oolitic flora: nor is it probable that a species of vegetation which the old Yorkshire of the Oolite possessed, the old Scotland of the Oolite should have wanted ; though I have not yet succeeded in finding the remains of palms in any of our Scotch deposits. The animal productions of our country during this early period were divided, like those of the present time, into the four great Cuvierian divisions, all of which we still find in a fossil state in our rocks. Corals akin to the trop- ical forms, some of them of great size, with star-fishes and sea-eggs, represent the radiata ; a fossil lobster which occurs in the Lias of Cromarty somewhat meagrely repre- sents the articulata. The shelled mollusca we find very largely represented in almost all their classes and families, from the high Cephalopods to the low Brachipods ; and in this division the peculiar character of the Oolitic system is more strongly impressed than even on its flora. Its corals, though many of them of great size, as I have just said, LECTURES ON GEOLOGY. 193 and of elegant form, might almost pass for those of the intertropical seas of the present day ; nor are its Crustacea and insects, even where best preserved, as in the Oolites of England, of a character widely different from those which still exist. But by much the larger part of its mollusca bear the stamp of a fashion that has perished. It is chiefly, however, in its molluscs of the first class, the Cephalopods, creatures of a high standing in their division, and represented in the present day by the nauti- lus and the cuttle-fish, that we recognize in its fullest extent this extinct peculiarity of type and form. Its Brachipods, chiefly terebratulae, not unfrequent in the Sutherland Ooli- tes, and in the Lias of Cromarty and Skye, its periwin- kles, whelks, avicula?, pinna, pectens, oysters, and mussels, few of them wanting in any of our Scotch Liassic or Ooli- tic deposits, and many of them very abundant, though all specifically extinct, present us, though with a large admix- ture of strange and exotic forms, with many other forms with which, generically, at least, we are familiar. But among the Cephalopods all is strange and unwonted ; and their vast numbers greater at this period of the world's history than in any former or any after time have the effect of imparting their own unfamiliar character to the whole molluscan group of the Oolite. I need but refer to two families of these, the Belemnite family and the fam- ily of the Ammonites ; both of them so remarkable, that they attracted in their rocks -the notice of the untaught inhabitants of both England and Scotland, and excited their imagination to the point at which myths and fables are produced, long ere Geology existed as a name or was known as a science. The Belemnites are the old thunder- bolts of the north of Scotland, that, in virtue of their sup- posed descent from heaven, were deemed all potent in 17 l'J4 LECTURES ON GEOLOGY. certain cases of bewitchment and the Ammonites are those charmed snakes of the mediaeval legend, " That each one Was changed into a coil of stone, When holy Hilda prayed." The exact affinities of the Belemnite family have formed a subject of controversy of late years among our highest authorities, men such as Professor Owen taking up one side, and men such as Dr. Mautell the other. But there can be little doubt that it more nearly approached to our existing cuttle-fishes than to any other living animals; while there is no question that its contemporary the Am- monite is now most nearly represented, though of course only approximately, by the nautilus. The Belemnite ex- isted in some of its species throughout all the formations of the great Secondary division, but neither during those of the Palaeozoic nor yet of the Tertiary divisions ; the Ammonite, on the other hand, though in an extreme and aberrant form, preceded it by several formations, but be- came extinct at the same time, neither Ammonite nor Belemnite outliving the deposition of the Chalk. The first great division of the animal kingdom, the vertebrata, was represented in Scotland during the Oolitic period by fishes and reptiles. Its fishes seem to have been restricted to two orders, that placoid order to which the existing sharks belong, and that ganoid order, now well- nigh worn out in creation, to which the Lepidosteus of the North American lakes and rivers belongs, and to which I incidentally referred in connection with the Lepidotus of the Weald. I have found in the island of Eigg beds of a limestone composed almost entirely of fossil shells, which were strewed over with the teeth of an extinct LECTURES ON GEOLOGY. 195 genus of sharks, the Hybodonts; and I have seen the dorsal spines of the same placoid division occasionally occurring among the Oolites of Sutherland and the Lias of Eathie. And scales, cerebral plates, and in some in- stances considerable portions of individuals of the ganoidal species, glittering in the enamel to which they owe their name, occur in all the Oolitic deposits of Scotland. Of our Scottish reptiles of the Oolite we have still a good deal to learn. I was fortunate enough in 1844 to find in a deposit of Eigg, and again at Helmsdale in 1849, the remains of several of its more characteristic Enaliosaurs, or bepaddled reptiles of the sea; at Helmsdale I found vertebral joints of the Ichthyosaurus in a conglomerate lower in the Oolite ; and in Eigg, in a stratum composed of littoral univalves, vertebral joints, phalanges, and por- tions of the humerus and of the pelvic arch of Plesiosau- rus, together with the limb-bones of crocodileans, and fragments of the carapace of a tortoise. Previous, how- ever, to even the earlier date of my discoveries, the tooth of a Saurian had been found in the Sutherlandshire Oolite by Mr. (now Sir Roderick) Murchison, and the limb-bone of a Chelonian with a sauroid vertebra, in the outlier of the Moray shire Weald at Linksfield. My collection, how- ever, though still very inadequate in this department, con- tains, in quantity at least, and, I am disposed to think, in variety also, some eight or ten times more of the reptilian remains of Scotland, during the Secondary ages, than all the other collections of the kingdom. They at least serve to demonstrate that the Oolitic period in what is now our country was, as in England and on the Continent, a period of huge and monstrous reptiles, that the bepaddled Enaliosaurs, the strange reptilian predecessors of the Ce- tacea, haunted our seas in at least two of their generic 196 LECTURES ON GEOLOGY. forms, that of the Ichthyosaur and that of the Ple- siosaur; that our livers were frequented by formidable crocodiles ; and that tortoises of various perished species lived in our lakes and marshes, or, according to their na- tures, disported on the drier grounds. Nor is it probable that the other reptilian monsters of the time, the con- temporaries of these creatures in England, would have been wanting here. We may safely infer that flocks of Pterodactyles reptiles mounted on bat-like wings, and as wild and monstrous in aspect and proportion as roman- cer of the olden time ever feigned fluttered through the tall pine-forests, or perched on the cycadeas and the tree-ferns; that the colossal Iguanodon and gigantic Hy- laeosaurus browsed on the succulent equisetaceae of the low meadows; that the minute Amphitherium, an insec- tivorous mammal of the period, lodged among the ferns on the drier grounds, where extinct grasshoppers chirped throughout the long bright summer, and antique coleoptera burrowed in the sand ; and that far off at sea there were moments when the sun gleamed bright on the polished sides of the enormous Cetiosaurus, as it rose from the bot- tom to breathe. But I must close this part of my subject, the Scottish flora and fauna of the Oolite, on which my'narrow limits permit me, as you see, to touch at merely a few salient points, with two brief remarks. First, So rich was its flora, that its remains formed on the east coast of Sutherland a coal, or rather lignite field, so con- siderable that it was wrought for greatly more than a cen- turv > at one time to such effect, that during the twelve years which intervened between 1814 and 1826, no fewer than seventy thousand tons of coal were extracted from one pit. Second, The strange union which we find in the -ame beds of trees that seem to have languished under LECTURES ON GEOLOGY. 197 chill and severe skies, with plants, corals, and shells of a tropical or serai-tropical character, need not be regarded as charged with aught like conflicting evidence respecting the climatal conditions of the time. Climate has its zones marked out as definitely by thousands of feet on our hill- sides as by degrees of latitude on the surface of the globe ; and if the Scotland of the Oolitic period was, as is prob- able, a mountainous country traversed by rivers, produc- tions of an intertropical, and of even a semi-arctic char- acter, may have been not only produced within less than a day's journey of each other, but their remains may have bejtm mingled by land-floods, as we find the huge corals of Helmsdale blent with its slow-growing pines, among the debris of some littoral bed. The poet's exquisite descrip- tion of Lebanon suggests, I am disposed to think, the true reading of the enigma : " Like a glory the broad sun Hangs over sainted Lebanon, Whose head in wintry grandeur towers, And whitens with eternal sleet; While summer, in a vale of flowers, Is sleeping rosy at his feet." The mere lists of the botanist and zoologist are in them- selves repulsive and un-ideaed; and yet the existences which their arbitrary signs represent are the vital marvels of creation, the noble forests, fair shrubs, and delicate flowers, and the many-featured denizens of the animal world, so various in their forms, motions, and colors, and so wondrous in their structure and their instincts. I have been presenting you this evening with little else than a dry list of the Scottish productions of the Wealden and Oolitic ages, a list necessarily imperfect, and all the more unsuggestive from the circumstance that, as myriads of 17* 198 LECTURES ON GEOLOGY. ages had elapsed between the extinction of the races and families which its signs represent, and their first applica- tion as slims, so these signs, in their character as vocables, belong to languages as dead as the organisms themselves. The organisms were dead and buried, and converted into lignite or stone, long ages ere there was language enough in the world to furnish them with names; and now the ;:! I has been employed to designate the dead, dead languages to designate the remains of dead creations. Could we but see the productions of our country as they once really existed, could we travel backwards into the vanished past, as we can descend into the strata that con- tain their remains, and walk out into the woods, or along the sea-shores of old Oolitic Scotland, we should be greeted by a succession of marvels strange beyond even the conceptions of the poet, or at least only equalled by the creations of him, who, in his adventurous song, sent forth the Lady Una to wander over a fairy land of dreary wolds and trackless forests, whose caverns were haunts of dragons and satyrs, and its hills the abodes " Of dreadful beasts, that, when they drew to hande, Half-flying and half-floating, in their haste, Did with their largeness measure o'er much lande, And made wide shadow under bulksome waist, As mountain doth the valley overcaste; And trailing scaly tails did rear afore Bodies all monstrous, horibill, and vaste." Let us, however, ere we part for the evening, adventure a short walk into the wilds of the Oolitic, in that portion of space now occupied on the surface of the globe by the north-eastern hills of Sutherland, where they abut on the jnvrij.jtniis Onl. W e stand on an elevated wood-covered ridge, that on LECTURES ON GEOLOGY. 199 the one hand overlooks the blue sea, and descends on the other towards a broad river, beyond which there spreads a wide expanse of a mountainous, forest-covered country. The higher and more distant hills are dark with pines; and, save that the sun, already low in the sky, is flinging athwart them his yellow light and gilding, high over shaded dells and the deeper valleys, cliff, and copse, and bare mossy summit, the general coloring of the background would be blue and cold. But the ray falls bright and warm on the rich vegetation around us, tree-ferns, and tall club-mosses, and graceful palms, and the strangely proportioned cycadaceaB, whose leaves seem fronds of the bracken fixed upon decapitated stumps; and along the banks of the river we see tall, intensely green hedges of the feathered equisetacea3. Brown cones and withered spiky leaves strew the ground; and scarce a hundred yards away there is a noble Araucarian, that raises, sphere- like, its proud head more than a hundred feet over its fellows, and whose trunk, bedewed with odoriferous bal- sam, glistens to the sun. The calm stillness of the air makes itself faintly audible in the drowsy hum of insects ; there is a gorgeous light-poised dragon-fly darting hither and thither through the minuter gnat-like groupes; it settles for a moment on one of the lesser ferns, and a small insectivorous creature, scarce larger than a rat, issues noiselessly from its hole, and creeps stealthily towards it. But there is the whirr of wings heard overhead, and, lo! a monster descends, and the little mammal starts back into its hole. 'Tis a winged dragon of the Oolite, a carnivor- ous reptile, keen of eye and sharp of tooth, and that to the head and jaws of the crocodile adds the neck of a bird, the tail of an ordinary mammal, and that floats through the air on leathern wings resembling those of the great vampire 200 LECTURES ON GEOLOGY. bat. We have seen, in the minute, rat-like creature, one of the two known mammals of this vast land of the Oolite, the insect-eating AmpMtherium ; and in the flying reptile, one of its strangely organized Pterodactyls. But hark ! what sounds are these? Tramp, tramp, tramp, crash, crash. Tree-fern and club-moss, cycas and zamia, yield to the force and momentum of some immense reptile, and the colossal Iguanodon breaks through. He is tall as the tallest elephant, but from tail to snout greatly more than twice as long; bears, like the rhinoceros, a short horn on his snout; and has his jaws thickly implanted with saw-like teeth. But, though formidable from his great weight and strength, he possesses the comparative inoffensiveness of the herbivorous animals ; and, with no desire to attack, and no necessity to defend, he moves slowly onward, deliberately munching, as he passes, the succulent stems of the cycadacea. The sun is fast sinking, and, as the light thickens, the reaches of the neighboring river display their frequent dimples, and ever and anon long scaly backs are raised over its surface. Its numerous crocodileans are astir ; and now they quit the stream, and we see its thick hedge-like lines of equisetaceae open and again close, as they rustle through, to scour, in quest of prey, the dank meadows that line its banks. There are tortoises that will this evening find their protecting armor of carapace and plastron all too weak, and close their long lives of centuries. And now we saunter downwards to the shore, and see the ground-swell breaking white in the calm against ridges of coral scarce less white. The shores are strewed with shells of pearl, the whorled Ammonite and the Nautilus; and amid the gleam of ganoidal scales, reflected from the green depths beyond, we may see the phosphoric trail of the Belemnite, and its path is oter LECTURES ON GEOLOGY. 201 shells of strange form and name, the sedentary Gryphaea, the Perna, and the Plagiostoma. But lo! yet another monster. A snake-like form, sur- mounted by a crocodilean head, rises high out of the water within yonder coral ledge, and the fiery, sinister eyes peer inquiringly round, as if in quest of prey. The body is but dimly seen ; but it is short and bulky compared with the swan-like neck, and mounted on paddles instead of limbs ; so that the entire creature, wholly unlike anything which now exists, has been likened to a boa constrictor threaded throngh the body of a turtle. We have looked upon the Plesiosaurus. And now outside the ledge there is a huge crocodilean head raised ; and a monstrous eye, huger than that of any other living creature, for it measures a full foot across, glares upon the slimmer and less powerful reptile, and in an instant the long neck and small head dis- appear. That monster of the immense eye, an eye so consti'ucted that its focus can be altered at will, and made to comprise either near or distant objects, and the organ itself adapted either to examine microscopically or to ex- plore as a telescope, is another be-paddled reptile of the the sea, the Ichthyosaurus, or fish-lizard. But the night comes on, and the shadows of the woods and rocks deepen: there are uncouth sounds along the beach and in the forest ; and new monsters of yet stranger shape are dimly dis- covered moving amid the uncertain gloom. Reptiles, rep- tiles, reptiles, flying, swimming, waddling, walking; the age is that of the cold-blooded, ungenial reptile ; and, save in the dwarf and inferior forms of the marsupials and insectivora, not one of the honest mammals has yet ap- peared. And now the moon rises in clouded majesty ; and now her red wake brightens in one long strip of the dark sea*; and we may mark where the Cetiosaurus, a sort of 202 LECTURES ON GEOLOGY. reptilian whale, comes into view as it crosses the lighted tract, and is straightway lost in the gloom. But the night grows dangerous, and these monster-haunted woods were not planted for man. Let us return then to the safer and better furnished world of the present time, and to our secure and quiet homes. LECTURE FIFTH. The Lias of the Hill of Eathie The Beauty of its Shores Its Deposits, how formed Their Animal Organisms indicative of successive Platforms of Exist- ences The Laws of Generation and of Death The Triassic System Its Economic and Geographic Importance Animal Footprints, but no Fossil Organisms found in it The Science of Ichnology originated in this fact Illus- trated by the appearance of the Compensation Pond, near Edinburgh, in 1842 The Phenomenon indicated by the Footprints in the Triassic System The Trias- sic and Permian Systems once regarded as one, under the name of the New Red Sandstone The Coal Measures in Scotland next in Order ot' Succession to the Triassic System Differences in the Organisms of the two Systems Extent of the Coal Measures of Scotland Their Scenic Peculiarities Ancient Flora of the Carboniferous Period Its Fauna Its Reptiles and Reptile Fishes The other Organisms of the Period Great Depth of the System The Pro- cesses by which during countless Ages it had been formed. THE Lias forms, as I have already had occasion to re- mark, the base of the great Oolitic system. I dealt in my last address with the productions, vegetable and animal, of those long ages of the world's history which the various deposits of this system represent, and attempted a restora- tion of some of its more striking scenes, as they must have existed of old, in what is now Scotland. But in glancing once more at the Lias, we must pass from the living to the dead, from the vital myriads that once were, to the cemetery that contains their remains. I shall select as my example a single Liassic deposit of Scotland, but in several respects one of the most remarkable, that of Eathie, on the shores of the Moray Frith, about four miles from the town of Cromarty. And in visiting it in its character as a great burial-ground, the final resting-place, not only of 204 LECTURES ON GEOLOGY. perished individuals, but also of extinct tribes and races, and in scanning its strangely sculptured monuments, rough- ened with hieroglyphics, to which living nature furnishes the key, we may perhaps be permitted to indulge in some of those reflections which so naturally suggest themselves in solitary churchyards, or among the tombs of the ancient dead. The hill of Eathie is a picturesque eminence of granitic gneiss, largely mixed with beds of hornblende schist, which extends, in a long precipitous ridge, some five or six hun- dred feet in height, along the northern side of the Moray Frith, and forms one of a primary chain of hills, which, in their upheaval, uptilted deposits of the Lias and Oolite. The deposit which the hill Eathie disturbed is exclusively a Liassic one : the upturned edge of the base of the forma- tion rests against the bottom of the hill ; and we may trace the edges of its various upper deposits for several hundred feet outwards, bed above bed, until, apparently near the top of the formation, we lose them in the sea. There is a wild beauty on the shores of Eathie. A s'elvage of com- paratively level ground, that occupies the space between the rocky beach and an inflection of the hill, seems em- bosomed in solitude; the naked scaurs and furze-covered slopes, where the fox and the badger breed, interpose their dizzy fence between it and the inhabited portions of the country above; while the rough unfrequented shore and wide-spreading sea form the secluding barriers below. The only human dwellings visible are the minute specks of white that look out in the sunshine from the dim and diluted blue of the opposite coast; and we may see the lonely frith broadening and widening as it recedes from the eye, and opens to the ocean in a direction so uninter- rupted by land, that the waves, which, when the wind LECTURES ON GEOLOGY. 205 blows from the keen north, first begin to break on the dis- tant headlands, and then come running up the coast, like white coursers, may have heaved their first undulating movements under the polar ice. The scene seems such a one as the anchorite might choose to wear out life in, far from the society of fellow-man ; and we actually find, in exploring its bosky thickets of wild rose and sloe-thorn, that some anchorite of the olden time did make choice of it. A gray shapeless hillock of lichened stone, shaded by luxuriant tufts of fern, still bears the name of the old chapel; and an adjacent spring, on whose overhanging sprays of ivy we may occasionally detect minute tags of linen and woollen cloth, the offerings of a long-derived superstition, not quite extinct in the district, is still known as the Saint's Well. But who the anchorite was, tradition has long since forgot ; and it was only last year that I succeeded in recovering the name of the saint from an old man, whose father had been a farmer on the land considerably more than a hundred years before. The chapel and spring had been dedicated, he said, to St. Ken- nat, a name which we need scarce look for in the Romish Calendar, but which designated, it is probable, one of our old Culdee saints. The various beds of the Eathie deposit, all, save the lowest, which consists of a blue adhesive clay, are com- posed of a dark, finely laminated shale ; and, varying in thickness from thirty feet to thirty yards, they are curi- ously separated from each other by bands of fossiliferous limestone. And so impalpable a substance are these shales, that, when subjected to calcination, which is neces- sary to extract the bitumen with which they are charged, and which gives them toughness and coherency, they re- solve into a powder, used occasionally, from its extreme 18 206 LECTURES ON' GEOLOGY. fineness, in the cleaning of polished brass and copper. They were laid down, it is probable, in circumstances similar to those in which, as described by the late Captain Basil Hall, extensive deposits are now taking place in the Yellow Sea of China. "At sunset," says Captain Hall, in the narrative of his voyage to Loo-Choo, " no land could be perceived from the mast-head, although we were in less than five fathoms water. And before the day broke next morning, the tide had fallen a whole fathom, which brought the ship's bottom within three feet of the ground. It was soon afterwards discovered that she was actually sailing along with her keel in the mud, which was sufficiently in- dicated by a long yellow train in our wake. Some incon- venience was caused by this extreme shallowness, as it re- tarded our headway, and affected the steering ; but there was in reality not much danger, as it was ascertained, by forcing long poles into the ground, that for many fathoms below the surface on which the sounding lead rested, and from which level the depth of water is estimated, the bot- tom consisted of nothing but mud formed of an impalp- able powder, without the least particle of sand or gravel." The Liassic deposit of Eathie must have been of slow de- position. It consists of lamina as thin as sheets of paste- board, which, of course, shows that there was but little deposited at a time, and pauses between each deposit. And, though a soft muddy surface could have been of it- self no proper habitat for the sedentary animals, serpulae, oysters, gryphites, and terebratulas, we can find farther, that they did, notwithstanding, find footing upon it, by at- taching themselves to the dead shells of such of the sailing or swimming molluscs, Ammonites and Belcmnites, as died over it, and left upon it their remains ; from which we in- fer that the pauses must have been very protracted, seeing LECTURES ON GEOLOGY. 207 that they gave time sufficient for the Terebratulae, shells that never moved from the place in which they were origi- nally fixed, to grow up to maturity. The thin leaves of these Liassic volumes must have been slowly formed and deliberately written ; for as a series of volumes, reclining against a granite pedestal in the geologic library of nature, I used to find pleasure in regarding them. The limestone bands, curiously marbled with lignite, ichthyolite, and shell, formed the stiff boarding ; and the thin pasteboard- like laminae between, tens and hundreds of thousands in number in even the slimmer volumes, composed the closely written leaves. For never did characters or figures lie closer in a page than the organisms on the surfaces of these leaf-like laminas. Permit me to present you from my note-book with a few readings taken during a single visit from these strange pages. We insinuate our lever into a fissure of the shale, and turn up a portion of one of the laminae, whose surface had last seen the light when existing as part of the bottom of the old Liassic sea, when more than half the formation had still to be deposited. Is it not one of the prints of Sower- by's "Mineral Conchology" that has opened up to us? Nay, the shells lie too thickly for that, and there are too many repetitions of organisms of the same species. The drawing, too, is finer, and the shading seems produced rather by such a degree of relief in the figures as may be seen in those of an embossed card, than by any arrangement of lighter and darker color. And yet the general tone of the coloring, though dimmed by the action of untold cen- turies, is still very striking. The ground of the tablet is of a deep black, while the colors stand out in various shades, from opaque to a silvery white, and from silvery white to deep gray. There, for instance, is a group of 208 LECTURES ON GEOLOGY. large Ammonites, as if drawn in white chalk; there, a clus- ter of minute bivalves resembling Pectens, each of which bears its thin film of silvery nacre; there, a gracefully formed Lima in deep neutral tint; while, lying athwart the page, like the dark hawthorn leaf in Bewick's well- known vignette, there are two slim sword-shaped leaves colored in deep umber. We lay open a portion of another page. The centre is occupied by a large Myacites, still bearing a warm tint of yellowish brown, and which must have been an exceedingly brilliant shell in its day ; there is a Modiola, a smaller shell, but similar in tint, though not quite so bright, lying a few inches away, with an assem- blage of dark gray Gryphites of considerable size on the one side, and on the other a fleet of minute Terebratulas, that had been borne down and covered up by some fresh deposit from above, when riding at their anchors. We turn over yet another page. It is occupied exclu- sively by Ammonites of various sizes, but all of one species, as if a whole argosy, old and young, convoyes and convoyed, had been wrecked at once, and sent disabled and dead to the bottom. And here we open yet another page more. It bears a set of extremely slender Belem- nites. They lie along and athwart, and in every possible angle, like a heap of boarding-pikes thrown carelessly down a vessel's deck on the surrender of the crew. Here, too, is an assemblage of bright black plates, that shine like pieces of japan work, the cerebral plates of some fish of the ganoid order ; and here an immense accumulation of minute glittering scales of a circular form. We apply the microscope, and find every little interstice in the page covered with organisms. And leaf after leaf, for tens and hundreds of feet together, repeats the same strange story." The great Alexandrian library, with its unsununed tonic; LECTURES ON GEOLOGY. 209 of ancient literature, the accumulation of long ages, was but a poor and meagre collection, scarce less puny in bulk than recent in date, when compared with this vast and wondrous library of the Scotch Lias. Now, this Eathie deposit is a crowded burying-ground, greatly more charged with remains of the dead, and more thoroughly saturated with what was once animal matter, than ever yet was city burying-ground in its most unsani- tary state. Every limestone band or nodule, yields, when struck by the hammer, the heavy fetid odor of corruption and decay; and so charged is the laminated shale with an animal-derived bitumen, that it flames in the fire as if it had been steeped in oil, and yields a carburetted hydro- gen gas scarce less abundantly than some of our coals of vegetable origin. The fact of the existence, through- out all the geological ages, of the great law of death, is a fact which must often press upon the geologist. Almost all the materials of his history he derives from cenotaphs and catacombs. He finds no inconsiderable portion of the earth's crust composed of the remains of its ancient inhabitants, not of dead individuals merely, but also of dead species, dead genera, nay, of even dead creations ; and here, where the individual dead lie as thickly on the surface of each of many thousand layers as leaves along the forest glades in autumn, here, where all the species and many of the genera are dead, nay, where the whole creation represented by its multitudinous- organisms is dead, the great problem which this law of death pre- sents comes upon the explorer in its most palpable and urgent form. The noble verses of James Montgomery, somewhat exagerative in their character when addressed to a molehill, become as remarkable for their sober pro- priety as for their beauty when employed here: 18* 210 LECTURES ON GEOLOGY. " Tell me, thou dust beneath my feet, Thou dust that once hadst breath, Tell me how many mortals meet In this small hill of death? By wafting winds and flooding rains, From ocean, earth and sky, Collected, here the frail remains Of slumbering millions lie. The mole that scoops, with curious toil, Her subterranean bed, Thinks not she ploughs so rich a soil, And mines among the dead. But ! where'er she turns the ground, My kindred earth I see; Once every atom of this mound Lived, breathed, and felt like me. Like me, these elder-born of clay Enjoyed the cheerful light, Bore the brief burden of a day, And went to rest at night. Mcthinks this dust yet heaves with breath, Ten thousand pulses beat : Tell me, in this small hill of death How many mortals meet." What does this inexorable law of death mean, or on what principle does it depend ? In our own species it has a moral significancy, "Death reigned from Adam," and though a pardonable mistake, no longer insisted on by at least theologians of the higher class, the same moral character, as a reflex influence, has been made to attach to it in its inevitable connection with the inferior animals. But in them, it seems to have no moral significancy. Bacon makes a shrewd distinction, in one of his Essays, between "death as the wages of sin," and death as "a tribute due to nature;" and we can now fully appreciate LECTURES OX GEOLOGY. 211 the value of /the distinction. For we now know that while, as the wages of sin, it has reigned from but the fall of Adam, it has reigned as a tribute due to nature throughout the long lapse of the geologic ages from the first beginnings of life upon our planet. What, then, does this inexorable law of death mean ? and on what principle does it depend? It was in mere cobweb toils that those Sadducees who believed " not in angel, neither in spirit," endeavored to entangle our Saviour, when they propounded to him the case of the woman with the seven husbands, and de- map ded whose wife of the seven she was to be in the Resurrection. But there was a profundity in the reply, which the theologians of nearly two thousand years have, I am disposed to think, failed adequately to comprehend. " The children of this world marry and are given in mar- riage," he said, "but the children of the Resurrection neither marry nor are given in marriage, neither can they die any more." Now there seems to be a strictly logical sequence between the two distinct portions of this pro- position, the enunciation that the denizens of the state after death do not marry, and the enunciation that they do not die, which for eighteen centuries there was not science enough in the world adequately to appreciate. The marriage provision was simply a provision tanta- mount to the original injunction, not of paradise merely, but of every preceding period in which there were organi- zations of matter possessed by the vital principle: "In- crease and multiply, and replenish the earth." And all geology presses upon us the conviction, so powerfully enforced by the Liassic deposit at Eathie, that, from the very nature of things, the law of generation and the law of death, wherever space is limited, cannot be dissociated. 212 LECTURES ON GEOLOGY. Each of the multitudinous leaves of the Lias formed in succession an upper surface, or platform, on which, for a certain period of time in the world's history, living and sentient creatures pursued the several instincts of their natures, and then ceased to exist. And so immense, in many instances, was the crowd, that, had the existence of two platforms been restricted to the occupancy of only one platform, they would have lacked footing. A dense crowd of living men may find ample standing-room in an ancient city churchyard, occupying, as they do, a different stratum of space from that occupied by the dead; but were the dead to revive and arise, it would be impossible that the living could find in it the necessary standing- room any longer. They would be jostled from their places far beyond the limits of the inclosing wall. And let us remember, that " the great globe itself which we inherit " is all one vast burying-ground ; nor is it to one stratum that the densely piled remains of its dead are restricted, nor to one hundred, nor to one thousand, nor yet to one hundred thousand strata. Even in this deposit of the Eathie Lias, the successive platforms of the dead may be reckoned up by thousands and tens of thousands; and it would be more possible that a fertile field should have growing upon it at once the harvests of ten thousand succeeding autumns, than that any one of the platforms should have living upon it at once the existences of all the innumerable platforms above and below. The great law " increase and multiply " gave to each platform its count- less crowds ; and to make room for the continuous opera- tion of this law, the other great law of death came into action, and so the generations of succeeding periods found space to pursue their various instincts on platforms com- posed in no small part of the perished generations from LECTURES ON GEOLOGY. 213 which they had sprung. Throughout the whole incalcula- ble past of our planet, throughout all its unmeasured and immeasurable periods, the laws of production and decay have gone inseparably together; they were twin stars on the horizon, tinged by the complementary colors, and so inseparably associated, that the appearance of the one always heralded the rise of the other. And to my mind at least, it does seem demonstrative of the full-orbed and perfect wisdom of the Divine Master of the Theolo- gians, that He, with that quiet simplicity which Pascal so well designates the characteristic style of Godhead, and with a logic too profound to be appreciated at the time, should have coupled together the twin laws of production and decay, as equally inadmissible into that future state in which the life of man is to be no longer " Summed up in birthdays and in sepulchres." " The children of the resurrection neither marry nor are given in marriage, neither can they die any more." From the Oolite, with its Liassic base, we pass on to the Triassic system, a deposit less characteristically de- veloped in England than on the Continent, but of much economic importance, from those vast beds of rock-salt which, in Britain, at least, are exclusively restricted to this system; and of considerable geographic importance, from its great lateral extent. In Scotland 1 it occupies rather more than a hundred square miles of surface, chiefly in Dumfriesshire, along the northern shores of the Solway, 1 There is good reason to believe that the red rocks overlying the coal of Cumberland, the red sandstones of Corncockle Muir, near Dumfries, the Ayrshire red sandstones, and those of the Isle of Arran, are all of the Permian, not Triassic, epoch. See " Siluria," new edition, p. 351. w. s. s. 214 LECTURES ON GEOLOGY. and in the line of boundary between the two kingdoms, where it can boast, among its other celebrities, of the famous village of Gretna Green, and the whole of Gretna parish. In England it is chiefly remarkable, in a scenic point of view, for its extreme flatness : its main feature is a want of features. It was, however, at one time, noto- rious for its ponds and marshes, consequents of the imper- fect drainage incident to flat low surfaces when of great extent ; and in Scotland, though so much more limited in area, it bears this character still. No fossil organisms have yet been found in this deposit in Scotland : it contains, however, in abundance, traces of the ancient inhabitants, even more curiously imprinted on the stone than if they had left in it the remains of their framework; and is interesting as the field in which, from the sedulous study of these, and undeterred by the skepticism of some of our highest authorities, the late Dr. Duncan, of Ruthwell, laid the first foundations of that curious and instructive de- partment of geologic science since known as Ichnology. The strange reptiles of this ancient time, in passing over the tide-uncovered beaches of the district, left their foot- steps imprinted in the yielding sand ; and in this sand, no longer yielding, but hardened long ages ago into solid rock, the footsteps still remain. And with truly wonder- ful revelations, revelations of things the most evanescent in themselves, and of incidents regarding which it might seem extravagant to expect that any record should remain, do we find these strange markings charged. They even tell us how the rains of that remote age descended, and how its winds blew. Let us see whether we cannot indicate a few of at least the simpler principles of this department of science. The artificial sheet of water situated among the Pentlands, and LECTURES ON GEOLOGY. 215 known as the Compensation Pond, was laid dry, during the warm summer of 1842, to the depth of ten fathoms; and as a lake bottom ten fathoms from the surface, is not often seen, I visited it, in the hope of acquiring a few facts that might be of use to me among the rocks. What first struck me, in surveying the brown sun-baked bottom from the shore, was the manner in which it had cracked, in the drying, into irregularly polygonal partings, and that the ripple-markings with which it was fretted extended along only a narrow border, where the water had been shallow enough to permit the winds or superficial currents to act on the soft clay beneath. As I descended, I found the surface between the partings indented with numerous well-marked tracks of the feet of men and animals, made while the clay was yet soft, and now fixed in it by the drying process, like the mark of the stamp in an ancient brick. And some of these tracks were charged with little snatches of incident, which they told in a style remarkably intelligible and clear. At one place, for in- stance, I found the footprints of some four or five sheep. They struck out towards the middle of the hollow, but turned upwards at a certain point, in an abrupt angle, towards the bank they had quitted, and the marks of increased speed became palpable. The prints, instead of being leisurely set down, so as to make impressions as sharp-edged as if they had been carved or modelled in the clay, were elongated by being thrown out backwards, and the strides were considerably longer than those in the downward line. And, bearing direct on the retreating footprints from the opposite bank, and also exhibiting signs of haste, I detected the track of a dog. The details of the incident thus recorded in the hardened mud were complete. The sheep had gone down into the hollow 216 LECTURES ON GEOLOGY. shortly after the retreat of the waters, and while it was yet soft; and the dog, either acting upon his own judg- ment, or on that of the shepherd, had driven them back. A little farther on I found the prints of a shoed foot of small size. They passed onwards across the hollow, the steps getting deeper and deeper as they went, until near the middle, where there were a few irregular steps, shorter, deeper, and more broken than any of the others; and then the marks of the small shoes altogether disappeared, and a small naked foot of corresponding size took their place, and formed a long line to the opposite bank. In this case, as in the other, the details of the incident were clear. Some urchin, in venturing across when the mud was yet soft and deep, after wading nearly half the way shod, had deemed it more prudent to wade the rest of it barefoot than to bemire his stockings. In each case the incident was recorded in peculiar characters ; and to read such characters aright, when inscribed upon the rocks, forms part of the proper work of the ichnologist. His key, so far at least as mere incident is concerned, is the key of circumstantial evidence ; and very curious events, as I have said, events which one would scarce expect to find recorded in the strata of ancient systems, does it at times serve to unlock. In some remote and misty age, lost in the deep obscu- rity of the unreckoned eternity that hath passed, but which we have learned to designate as the Triassic period, a strangely formed reptile, unlike anything which now exists, paced slowly across the ripple-marked sands of a lake or estuary. 1 It more resembled a frog or toad than 1 Reptiles are known to have existed from the period of the Old Red S:m 276 LECTURES ON GEOLOGY. ities, in some of their genera, to the sea-pens, and by cer- tain other affinities, in some of their other genera, to the Sertularia. They are known to the geologist by the gene- ral name of Graptolites. The Sertularia, compound, plant- like animals, that resemble miniature bushes in spring, just as the buds are bursting into leaf, are attached al- ways, by their seeming roots, to rocks, shells, or sea- weed, and so require a hard bottom; whereas the sea- pens, compound, feather-like Zoophites, whose every fibre contains its rows of living creatures, affect soft muddy bottoms, in which they may be found sticking by their quill-like points, like arrows in the soft sward around a target. I have seen them brought up by scores on the lines of the fisherman, out of a muddy ravine in the Mo- ray Frith, that sinks abruptly from beside the edge of a hard submarine bank, to the depth of thirty fathoms ; and have often admired their graceful, quill-like forms, and their delicate hues, that range from pink to crimson, and from crimson to purple. And, judging from the character of those gray carbonaceous deposits in which the Grap- tolites of our Silurian rocks most abound, it is probable that they also were mud-loving animals, and more resem- bled in their habitats, if not in their structure, the sea- pens than the Sertularia. It is a curious circumstance that, in the group at least, the Graptolites of Scotland are more obviously allied to the Graptolites of the vast Silu- rian deposits of Canada and the United States, than to those of the Silurians of England. With this curious zoophite we take farewell, in Scotland, of life and organ- ization, and the record of the paleontologist closes. The remains of no plant or of no animal have been detected in this country underlying the rocks in which the oldest Ornptolites occur. LECTURES ON GEOLOGY. 277 Beneath the SILURIAN deposits of Scotland there rest, to an enormous thickness, what, with the elder geologists, I shall persist in terming the primary deposits, consisting, in the descending order, of clay-slates, mica-schists, quartz- rocks, primary limestones, and the two varieties of gneiss, the granitic and the schistose. 1 In retaining the old name, I must, however, be regarded as merely holding that these rocks were actually the first-formed rocks of what is now Scotland, that the gneiss was gneiss, and the slate was slate, ere ever our oldest fossiliferous formations began to be deposited, or the organisms which they contain had lived or died. Into the question raised regarding the form in which they were deposited, or the condition of our planet during the period of their deposition, I do not at present enter. On the other point, however, the com- parative antiquity of these unfossiliferous rocks in Scot- land, the evidence seems very conclusive ; the base of some of the oldest deposits in which we find organisms inclosed consists of broken, and in most cases water- rolled, fragments of the gneisses, quartz-rocks, clay-slates, and mica-schists of the primary regions of the country. 2 These primary regions are of great extent. The gneiss region contains nearly ten thousand square miles of sur- face ; the mica-schist, fully three thousand ; and the quartz- rock and clay-slate united, about fourteen hundred miles more. Comprising almost all the Highlands of Scotland, with the greater part of two of our Lowland counties, Banfishire and Aberdeen, their entire area, if we add about fifteen hundred miles additional of granite and primary 1 Hugh Miller evidently MOKE THAN SUSPECTED the history of the geology of the north and northwest of Scotland, as developed by Mr. Peach and Sir Roderick Murehison in 1858. W. S. S. 2 See Murchison's " Siluria," 2d edition, App. 553, 554, and 556. 24 278 LECTURES ON GEOLOGY. porphyry, docs not fall short of sixteen thousand square miles. It would be a bold and perilous task for one who has in some degree appreciated those sublimely impres- sive word-paintings of the Highlands which have added so largely to the well-earned celebrity of your distinguished President, and which seem invested with the very atmos- phere of our hills, or who has seen with admiration and delight not only the very features, but all the poetry, of our noble mountain scenery, glowing from the canvas of Macculloch and of Hill, it would, I say, be a perilous task under the recollection of achievements such as theirs, to attempt a dull analysis of the geologic principles on which the peculiarities of our Highland landscape depend. I would feel as if I were bringing you from the studio of some heaven-taught sculptor, crowded Avith shapes of manly beauty and feminine loveliness, to lecture, amid the melancholy rubbish of a dissecting room, on the articula- tions and proportions of the bones, and the form and position of the muscles. I shall venture, therefore, on merely a few desultory remarks, and shall request you, in order to lighten them as much as possible, to accompany me, first, in a sort of mesmeric expedition to the western extremity of Glencoe ; at which, after having journeyed as only the clairvoyant can journey, let us now deem our- selves all safely arrived, and just set out on our way back again by the Locft Lomond road. In the course of our journey we shall pass, in the ascending order, over all the great Primary formations. 1 1 According to a diagram which I have had the honor of receiving from the hand of Sir Roderick Murchison, illustrating his latest explorations in the north, there are two distinct gneisses, an older and a younger ; the first underlying the Cambrian conglomerate and Silurian fossil-bearing baud of the west; the other or younger gneiss forming part of the central LECTURES ON GEOLOGY. 279 Let us first mark the character of the Glen, not less famous for the severe and terrible sublimity of its natural features, than for that dark incident in its history which associates in such melancholy harmony with the terrible and the severe. We are in a region of primary porphyry, in the main a dark-colored rock, though it is one of its peculiar traits, that in the course of a few yards it some- times changes its hue from dark green to black or a deep neutral tint, and from these again to chocolate color, to brick red, or to iron gray. But the prevailing hues are dingy and sombre; and hence, independently of the brown heath and ling, and those deep shadows which always accompany steep rocks and narrow ravines, a sombre tone in the coloring of the landscape. When, however, for a few days the atmosphere has been dry and the sky serene, the dark rocks seem in many parts as if strewed over with an exceedingly slight covering of new-fallen snow, the effect of the weathering of a thin film of the compact feld- spar, which forms the basis of the porphyry- into a white porcelanic earth. It is, however, in the form of the rocks that we detect the more striking peculiarities of the por- phyritic formation. They betray their igneous origin in their semi-columnar structure. Every precipice is scarred vertically by the thick-set lines which define the thin irreg- ular columns into which the whole is divided; and as the columnar arrangement is favorable to the production of tall steep precipices, deep narrow corries, and jagged and peaked summits, the precipices on either side are tall and steep, the corries are deep and narrow, and the summits nucleus, and underlying; the Old Red Sandstone conglomerates and ascend- ing fossiliferous series of the east. Of course, the Cambrian will contain fragments of the older, and the Old Red conglomerate fragments of the younger gneiss. L. M. 280 LECTURES ON GEOLOGY. are sharp, spine-like and uneven. A hill of primary por- phyry, where not too much pressed upon by its neighbor hills, as trees press upon one another in a thick wood, so that each checks the development of each, generally affects a pyramidal form ; and we find fine specimens of the reg- ularly pyramidal hill in the upper part of the valley, just as we enter on the open moor. I may mention, ere we quit Glencoe, that the more savagely sublime scenery of Scotland is almost all porphyritic.. There is only one other rock hypersthene which at all equals the pri- mary porphyry in this respect ; and hypersthene is of com- paratively rare occurrence in Scotland. It furnishes, how- ever, one very noble scene in the Isle of Skye : the stern and solitary valley of Corriskin, so powerfully described in the " Lord of the Isles," is a hypersthene valley. Emerging from Glencoe, we enter upon a scene that, in simple outline, abstracted from the dingy tone of the coloring, and the bleak and scanty vegetation common to both, contracts with it more strongly than perhaps any other in Scotland. We have quitted the porphyritic re- gion, and entered upon a region of granite and gneiss. Looking back from that most solitary of Scottish inns, King's House, we find that we can determine with much exactness, from the form of the hills, where the porphyry ends and the granite or gneiss begins. The last of the porphyritic hills is a noble pyramid, broken into dizzy prec- ipices, and lined vertically, like some of our semi-columnar traps ; whereas the first of the granitic hills, placed imme- diately beside it, with but a narrow valley between, is of rounded outline, a mere hummock magnified into a mountain, and wrapped round by a continuous cawl of brown heath. On the other hand, we see the granite rol- ling out into a moory plain, one of the dreariest in Scot- LECTURES ON GEOLOGY. 281 land, and forming a basin for a long, flat-shored loch, whose brown waters do not reflect a single human dwel- ling. Granite, however, does not always present features so little attractive. It is, in truth, a many-charactered rock. In general, the feldspar, which enters so largely into its composition, contains a considerable per centage of potash, and so decomposes readily ; and hence the rounded forms of many of our granite hills and boulders. It affects, too, on the large scale, though unstratified, a tabular ar- rangement, and sometimes exists, as in this instance, and in those dreary parts of the lowlands of Aberdeen where the patrimony of the redoubtable Sir Dugald Dalgetty lay, as extensive and usually very barren plains. But in other parts it has little or no potash in its composition ; and forming, in these circumstances, one of the most durable of rocks, its peaks and precipices stand up, as in Goatfell in Arran, with all the porphyritic sharpness of outline, un weathered for ages, or present, as in Ben Macdui and its Titanic compeers, features at once bold, broad, and sub- limely impressive. Humboldt, generally so correct in his "Views of Nature," seems to have seized on the granite in but one of its aspects. " All formations," we find him say- ing, " are common to every quarter of the globe, and as- sume the like forms. Everywhere basalt rises in twin mountains and truncated cones; everywhere trap porphyry presents itself to the eye under the form of grotesquely- shaped masses of rock ; while granite terminates in gently rounded summits." We pursue our journey, and enter on a great gneiss dis- trict. And in its swelling hills, rolled, like pieces of plain drapery, into but a few folds, and in its long withdrawing valleys, more imposing from an element of simple extent than from aught peculiarly striking in their contour, we 24* 282 LECTURES ON GEOLOGY. recognize the staple scenery of the Scotch Highlands, the scenery of ten thousand square miles. A gneiss hill is usually massive, rounded, broad of base, and withal some- what squat, as if it were a mountain well begun, but in- terdicted somehow in the building, rather than a finished mountain. It seems almost always to lack the upper stories and the pinnacles. It is, if I may so express myself, a hill of one heave; whereas all our more imposing Scottish hills, such as Ben Nevis and Ben Lomond, are hills of at le:ist two heaves; and hence, in journeying through a gneiss district, there is a frequent feeling on the part of the traveller that the scenery is incomplete, but that a few hills, judiciously set down upon the tops of the other hills, would give it the proper finish. No hill, however, accom- plishes more with a single heave than a gneiss one ; the broad-based Ben Wyvis, that raises its head, white with other snows than those of age, more than three thousand feet over the sea, and looks down on all the other moun- tains of Ross-shire, is a characteristic gneiss hill of a single heave. Quitting the gneiss region, we cross a compara- tively narrow strip of quartz rock. The quartz hills in its course are, however, not very characteristic. Such of you as may have sailed over the upper reaches of Loch Maree, Avith its precipitous, weather-bleached pyramidal hills, so bare of vegetation atop that their peaks may be seen gleaming white in the autumnal moonlight for miles, as if covered with snow, or who may have threaded your way through the deep and sterile valleys that open their long vistas towards the head of the lake, will be better able to conceive, than from aught witnessed in the course of our present day's journey, of the savage wildness of scenery savage and wild, but grand withal which is the proper characteristic of a quartz-rock district.- LECTURES ON GEOLOGY. 283 And now, the strip of quartz rock passed over, we enter into an extensive region of mica-schist, a formation so favorable to the development of a picturesque beauty, ever and anon rising into the sublime, that what is pecu- liarly the classic ground of Highland scenery is to be found within its precincts. Loch Awe, Loch Long, Loch Goil, Loch Tay, by much the larger and finer part of Loch Lo- mond, all Loch Katrine, Ben Venue, Ben Lerli, Ben Lo- mond, and the Trossachs, with many a fine lake and stream besides, and many a noble hill, are included in this rich province of the mica-schist. We first become aware that we are nearing the forma- tion by the peculiar contour of its hills, as seen at a dis- tance of several miles. As we approach their gray rocks of silky lustre, we find that they are curved, wrinkled, contorted, so as to remind us of pieces of ill-laid-by satin, that bear on their crushed surfaces the creases and crump- lings of a thousand careless foldings; and mark farther, that it is to these curves and contortions of the strata that the tubercled outlines of the hills are owing, and, with these, the bold projecting knobs and sudden recesses which break up their surfaces into so many picturesque wildernesses of light and shade. Not unfrequently, how- ever, vast masses of schist, of a structure as dense and solid as that of granite, occur in the micaceous districts; and these form hills of a simpler outline, which, like the rock which composes them, seem intermediate in character between the mica-schist and the gneiss hills. All the mica-schists, however, decompose into soils, which, though light and thin, are more favorable to the production of the grasses and the common dicotyledonous shrubs and trees of the Highlands," than any of the gneisses or granites, and greatly more so than the porphyries or quartz-rocks ; and 284 LECTURES ON GEOLOGY. so the micaceous regions are not only more picturesque in outline than any of the others, but also richer in foliage and softer in color. A tangled profusion of vegetation forms quite as marked a feature in the living and breath- ing description of the " Lady of the Lake," as the mural picturesqueness of the crags and precipices which the vegetation half conceals ; and this, be it remembered, is not an ordinary characteristic of the Scottish Highlands, though true to nature in the mica-schist region selected by Scott as the scene of his story. After employing, in describing the rocks near Loch Katrine, well nigh half the vocabulary of the architect, spires, pyramids and pinna- cles, towei-s, turrets, domes, and battlements, cupolas, minarets, pagodas, and mosques, he goes on to say, " Nor were these earth-born castles bare, Nor lacked they many a banner fair; * For from their shivered brows displayed, Far o'er the unfathomable glade, All twinkling with the dewdrop's sheen, The brier-rose fell in streamers green, And creeping shrubs of thousand dyes Waved in the west wood's summer sighs. Boon nature scattered free and wild Each plant or flower, the mountain's child. Here eglantine embalmed the air, Hawthorn and hazle mingled there, The primrose pale and violet flower Found in each cliff a narrow bower; Foxglove and nightshade, side by side, Emblems of punishment and pride, Grouped their dark hues with every stain The weather-beaten crags retain, With boughs that quaked with every breath; Gray birch and aspen wept beneath ; Aloft the ash and warrior oak Cast anchor in the rifted rock ; And higher yet the pine-tree hung His shattered trunk, and frequent flung, LECTURES ON GEOLOGY. 285 Where seemed the cliffs to meet on high, His boughs athwart the narrow sky." Here is there a description of the characteristic vegetation of our richer mica-schist valleys, not more remarkable for its poetic luxuriance than for its strict truth, truth so strict and literal, that I question whether even the hyper- critic, who looked for but a typical catalogue, could enu- merate more than two forms of vegetation, prevalent in such districts, which it does not include. The ferns grow at once singularly rank and delicate in the shade, amid the bosky recesses of the mica-schist ; and every damper recess of the rock we find thickly tapestried over by the mosses and the liverworts. Passing southwards along the dark surface of Loch Lomond, skirted for rather more than two-thirds of its length by these hills of mica-schist, which confer on its upper reaches a character of mingled picturesqueness and sublimity, we enter, nearly opposite the pastoral village of Luss, on a band of clay-slate, the last or most modern of the primary formations. It is of no great breadth, some three or four miles at most ; but it runs diagonally across the entire kingdom, from the western shores of Bute, where it disappears under the outer waters of the Frith of Clyde, to near Stonehaven, where we lose it in the German Ocean. We find it associated with a softer style of scenery than the mica-schist. Lacking the mul- titudinous contortions, and consequent knobs and pro- tuberances, of the schist, it is less picturesque, though scarce less beautiful; nor is its beauty devoid of an en- nobling mixture of the sublime. The gracefully-contoured hills that rise immediately behind Luss, with their recluse withdrawing valley, the green rolling meadoAv on which the village is built, and in front the bolder and finer 286 LECTURES ON GEOLOGY. islands of the lake, belong all to the clay-slate, and com- pose a very characteristic landscape. Dunkeld, Comrie, and the fine country to the north and west of Callendar, including Loch Vennacher, with many a scene besides/of a character intennediate, as becomes their place, between the Highlands and the Lowlands, occur in the belt of clay- slate that sweeps in its diagonal course from sea to sea. Leaving Luss behind us, we enter, ere quitting the lakes, on what is unmistakably the low country. The frame- work of the land before us and on either hand, with that of about one-half the lower islands of Loch Lomond, is all formed of the Old Red Sandstone ; and what Byron would perhaps term the "domestic beauties" of the pros- pect, swelling hills ploughed to the top, green lanes, rich meadows, and woods whose rectilinear edges still tell of the planter's line, bear evidence to the fact. The land, however, is that of Buchanan and of Smollett. Both were born on the Old Red Sandstone here; and the latter, in his well-known description of the lake, in "Humphrey Clinker," the product of a time when descriptions of Scottish scenery were less common than they are now, places in the foreground, in a style unmistakable from their truth, the features of this Lowland formation, which, in his age, was unfurnished with a name. " I have seen," he says, "the Lago di Garda, Albano, De Vico, Bolsina, and Geneva, and, upon my honor, prefer Loch Lomond to them all, a preference which is certainly owing to the verdant islands that seem to float upon its surface, afford- ing the most enchanting objects of repose to the excursive view. Nor are the banks destitute of beauties which even partake of the sublime. On this side they display a variety of woodland, corn-fields, and pasture, with several agreeable villas emerging, as it were, out of the lake, till, LECTURES ON GEOLOGY. 287 at some distance, the prospect terminates in huge moun- tains covered with heath. Everything here is romantic beyond imagination : the country is justly termed the Arcadia of Scotland." In the corn-fields here, the wood- lands, and the pastures, we recognize the Lowland features of the Old Red placed prominently in the foreground; and in the huge mountains in the distance, the bolder Highland features of the clay-slate and the mica-schist. In still journeying southwards, we skirt the banks of the Leven, the stream which connects .the waters of the lake with those of the Clyde, and which, for the greater part of its course, runs over an Old Red Sandstone of the same age as that of Balruddery, Carmylie, and Turin, and which presents as its characteristic organism, the Cepha- laspis. And nowhere in Scotland, as is well shown in Smollett's classical Ode, is there a more thoroughly Low- land river. "Pure stream, in whose transparent wave My youthful limbs I wont to lave ; No torrents stain thy limpid source, No rocks impede thy dimpling course, That sweetly warbles o'er its bed, With white, round, polished pebbles spread. Devolving from thy parent lake, A charming maze thy waters make, By bowers of birch and groves of pine, And hedges flowered with eglantine." Ere, however, closing our journey of a day, which intro- duces us to so interesting an epitome of the scenery of the primary rocks and the Scottish Highlands, we are startled in the midst of the low country by scenery which seems to be that of the Highlands repeated, but on a smaller scale, and, if I may so express myself, in a more mannered style. We pass over a narrow belt of the trap- 288 LECTURES ON .GEOLOGY. rocks, which, like the stratified deposits of this part of the kingdom, clay-slate and Old Red Sandstone, runs from sea to sea, and which, including in its range the Campsie and the Ochil hills, is here represented by the picturesque double-peaked rock which bears the ancient fortalice of Dumbarton, the castle which, according to Jeanie Deans's friend, Mr. Archibald, was always given in keeping to the best man in Scotland, at one time to Sir William "Wallace, at another to the Duke of Argyle. The depth of the primary stratified rocks, which in Scotland must be very great, has been variously estimated by geologists, as low as five and as high as ten miles, evidence enough, did we require any such, that there must be some degree of obscurity in the data on which the calculations regarding it have been founded. It is always extremely difficult to estimate the thickness of even a clay-slate or quartz-rock deposit in a mountainous coun- try, where the centres of disturbance are numerous and involved ; and in gneiss and mica-schist always greatly contorted deposits the difficulty is so enhanced, that what begins as calculation usually ends as guess. But we at least know that it can be no thin series of deposits, however much their strata may be contorted, or however often repeated, that covers, in highly inclined positions, tracts of country so extended as even those which we find covered by them in the Scotch Highlands. In crossing the four primary stratified deposits clay-slate, mica- schist, quartz-rock, and gneiss, at right angles with the line in which they traverse the country in the southern division of the Highlands, we find them occupying, as from near CriefF to Fort-Augustus, a tract rather more than sixty miles across ; and in crossing at the same angle the northern division of the Highlands, as from Glen LECTURES ON GEOLOGY. 289 TJrquhart to the middle reaches of Loch Carron, we find a tract of nearly forty miles occupied by the gneiss alone. The question is one on which I would not choose to dogmatize ; but an estimate that gave to our Scottish primary rocks an aggregate thickness of from six to eight miles I would not regard as by any means too high. A more vexed question, however, and a still more doubtful one, respects their formation. In what form, and under what circumstances, it has been often asked, and very variously* answered, were these stratified primaiy rocks deposited ? They exhibit with almost equal prominence two distinct classes of phenomena, an igneous class and an aqueous class; and are as intimately associated with the Pleistocene rocks by the one, as with the sedimentary rocks by the other. I have seen in the same quarry of quartz-rock, one set of strata as decidedly chemical in their texture as porphyry or hypersthene, and another intermingling set as decidedly mechanical as grauwacke or conglomerate. I have seen, too, in the same gneiss rock, the minute plates of mica, so abundant in this formation, arranged between the layers as decidedly on the sedimentary prin- ciple as in a micaceous sandstone, and in the layers them- selves as decidedly on the crystalline principle as in granite. And this compound character of the gneiss may be regarded as the general one, with, of course, certain exceptions in all the primary stratified rocks : the condi- tion of their stratification is mechanical and sedimentary, but the condition of the strata themselves igneous and chemical. How were these variously-blended characters first induced ? The geologists of one school tell us that the primary formations originally existed as ordinaiy sedi- mentary rocks, but that they have since been altered by *r 25 290 LECTURES ON GEOLOGY. the action of intense heat, and that, while the stratifica- tion remains as an evidence of their first condition, the texture of the strata indicates the igneous change which has passed over them; while the geologists of another school hold that their first deposition took place under circumstances essentially unlike any which now exist, on at least the surface of our planet, and that their inineralogical conditions were, in consequence, originally different from those of any deposition taking place at the present time, or in any of the later geological ages. I am inclined to hold that there is a wide segment of truth embodied in the views of the metamorphists ; but there seems to be also a segment of truth on the other side ; and so I must likewise hold with their antagonists, that there existed long periods in the history of the earth in which there obtained conditions of things entirely different from any which obtain now, periods during which life, either animal or vegetable, could not have existed on our planet; and further, that the sedimentary rocks of this early age may have derived, even in the forming, a constitution and texture which, in present circumstances, sedimentary rocks cannot receive. The scientific world is subject, like the worlds of politics and trade, to its periods of action and reaction. Those who hold that the earth was once a molten mass through- out, nay, that at a certain, not very profound, depth its matter may be still in an incandescent state, may have perhaps driven their theory too far; and the current at present seems to have set in against them. Mr. Hopkins's profound deductions on the phenomena of Precession and Nutation have been held to establish that the crust of the earth is at present a solid unyielding mass to the depth of at least a thousand miles from the surface. "Nay, there LECTURES ON GEOLOGY. 291 is nothing in this inquiry," says Professor Nichol, in refer- ring, in his late admirable work, " The Planetary System," to the problem of Mr. Hopkins, "there is nothing in this inquiry rendering it impossible that the globe is solid throughout ; and assuredly, a distinct negative is given to a whole class of prevalent geological conceptions, on grounds vastly more solid than any which appear to sus- tain them." And I find Sir Charles Lyell, in the latest edition of his " Principles," that of last year, suggest- ing the existence of a circle of superficial action on the earth's crust, quite sufficient to account for an intermittent igneous activity altogether independent of central heat, and which might go on by fits and starts forever, and be as powerful a million of years hence as in those incal- culably ancient times when our Scottish gneiss was in the forming. Accepting the theory of Sir Humphrey Davy, of an unoxidized metallic nucleus of the globe, capable of being oxidized all around its porphyry by the percolation of water, and of evolving heat enough in the process to melt the surrounding rocks, he thus provides plutonic, metamorphic, volcanic agencies; and whereas Sir Hum- phrey Davy held, that when a thick crust of oxide had once formed in this way, it served to shut out the water, and the chemical action became in consequence more and more languid, till it altogether ceased, Sir Charles finds, in another but harmonizing theory, an expedient for rein- vigorating the slumbering plutonic forces, and thus, after a period of repose, renewing their activity. The oxygen of the water is, of course, the oxidizing agent ; but water also contains hydrogen, and hydrogen is a deoxidizing agent. "When the oxidizing process was going on," says Sir Charles, "much hydrogen would of necessity be evolved : it would permeate the crust of the earth, and 292 LECTURES ON GEOLOGY. be stored up for ages in fissures and caverns ; and when- ever it happened to come in contact with the metallic oxides at a high temperature, the reduction of these oxides would be the necessary result." And we have thus a circle of forces, oxidization of the metallic basis to evolve the plutonic agencies, and deb'xidization of the oxides to produce the metallic basis again. The process would somewhat resemble that on which the movement of the steam-engine depends, and in which water is first expanded into steam, and then the steam in turn con- densed into water, and thus the action of the engine kept up. Now, I need not here say how thoroughly I respect the judgment and admire the genius of Sir Charles Lyell, one of the greatest of geologists, and a man of whom Scot- land may well be proud ; nor need I say how much of pleasure and instruction I owe to the rich and eloquent writings of Professor Nichol. But, like Job's younger friend, I too must take the liberty of showing forth my opinion, and of giving expression to a conviction, on grounds of which my audience must judge, that both Sir Charles and the Professor have suffered the reaction wave to carry them too far. Mr. Chai'les M'Laren, in a popular digest of Mr. Hop- kins's deductions, which first appeared, if I remember aright, in the "Scotsman" newspaper, and then in "Jame- son's Philosophical Journal," referred, with his character- istic caution, to the narrowness of the base on which they rested. "Mr. Hopkins's conclusion, no doubt, rests," he said, " on a narrow enough basis. It is somewhat like an estimate of the distance of the stars deduced from a differ- ence of one or two seconds in their apparent position, a difference scarcely distinguishable from errors of obser- LECTURES ON GEOLOGY. 293 vation." Let us, however, waive the doubt imp/ied in this remark, however important we may deem it, and grant, for the argument's sake, that the base is sufficiently broad for the superstructure erected upon it. Let us freely grant, after first availing ourselves of Mr. M'Laren's protest, and placing it on record, that that equatorial ring, thirteen miles in thickness, which, by disturbing the balance of the earth, is the cause of the phenomena of Precession and Nutation, must be attached to a consolidated crust of at least a thousand miles in thickness, in order to account for the extreme slowness of the peculiar movement which it induces. But let us then inquire how it happens that this equatorial ring at all exists. If our earth was always the stiff, rigid, unyielding mass that it is now, a huge metal- lic ball, bearing, like the rusty ball of a cannon, its crust of oxide, how conies it that its form so entirely belies its history ? Its form tells that it also, like the cannon ball, was once in a viscid state, and that its diurnal motion on its axis, when in this state of viscidity, e' ..gated it, through the operation of a well-known law, at the equator, and flattened it at the poles, and made it altogether the oblate spheroid which all experience demonstrates it to be. It may be urged, however, that this form of our planet, which seems to speak so unequivocally of law, may, after all, be but accident. If so, it must be singular. What say the other planets ? Of these, the form of three may be at least approximately, and that of one exactly, ascertained. Ve- nus, Mars, Saturn, are all, like our earth, oblate spheroids, flattened at their poles, and elongated at their equators. Their substance must have been spun out by their rotatory motion in exactly the line in which, as in the earth, that motion is greatest. But while we can only approximately determine the values of the equatorial and polar diameters 25* 294 LECTURES ON GEOLOGY. of these three planets, in one great planet, Jupiter, we can ascertain them scarce less exactly than in our own earth ; we can gauge, and measure, and fix the proportions which his equatorial ring bears to his general mass. With a diameter about eleven times larger than that of our planet, and rotating on his axis in less than half the time, the motion of the surface at his equator must be more than twenty times greater than that of the earth's equatorial surface, and his equatorial ring ought, even in proportion to his huge bulk, to be more than twenty times as massive. And what is the fact? While the thickness of the equato- rial ring of the earth is only equal to about one three-hun- dredth part of the earth's diameter, the equatorial ring of Jupiter is equal to about the one fourteenth or fifteenth part of his diameter. It is, as the integrity of the law demands, more than twenty times greater in proportion to his mass than the earth's equatorial ring, and absolutely more than two thousand times greater. Here, then, is demonstration tli ' the oblate sphericity of the earth is a consequence of the ea.th's diurnal motion on its axis ; nor is it possible that it could have received this form when in a solid state. A glass ball made to revolve on a spindle, when in a state of viscidity, elongates equatorially, and flattens at its poles ; but, if allowed to cool in its original form as a sphere, it retains its perfect sphericity without change, let us whirl it as rapidly as we may : and no me- chanic ever dreams of increasing the disk of a grindstone simply by turning it round. The earth, then, when it assumed its present form, could not have been a solidified mass, like the glass sphere when cooled down, or like the grindstone. But is it not possible, it may be asked, that the diurnal motion may so act on the depositions taking place in the LECTURES ON GEOLOGY. 295 sea, and forming sedimentary rock, or on a region of igne- ous action interposed between the oxidized crust of the earth and its solid metallic nucleus, and forming plutonic or igneous rock is it not possible that, in the course of vastly-extended periods, the earth may have taken its form under the influence of the motion exerted on sedimentary deposition and plutonic intrusion and upheaval? Nay, what, we ask in reply, are the facts ? Does the diurnal motion exercise any influence, even the slightest, on depo- sition or plutonic intrusion ? The laws of deposition are few, simple, and well known. The denuding and trans- porting agencies are floods, tides, waves, icebergs. The sea has its currents, the land its rivers ; but while some of these flow from the poles towards the equator, others flow from the equator towards the poles, uninfluenced by the rotatory motion ; and the vast depth and extent of the equatorial seas, show that the ratio of deposition is not greater in them than in the seas of the temperate regions. We have, indeed, in the arctic and antarctic currents, and the icebergs which they bear, agents of denudation and transport permanent in the present state of things, which bring detrital matter from the higher towards the lower latitudes ; but they stop far short of the tropics ; they have no connection with the rotatory motion ; and their influ- ence on the form of the earth must be infinitely slight ; nay, even were the case otherwise, instead of tending to the formation of an equatorial ring, they would lead to the production of two rings widely distinct from the equator. And, judging from what appears, we must hold that the laws of plutonic intrusion or upheaval, though more ob- scure than those of deposition, operate quite as independ- ently of the earth's rotatory motion. Were the case other- wise, the mountain systems of the world, and all the great 296 LECTURES ON GEOLOGY. continents, would be clustered at the equator ; and the great lands and great oceans of our planet, instead of run- ning, as they do, in so remarkable a manner, from south to north, would range, like the belts of Jupiter, from east to west. There is no escape for us from the inevitable con- clusion that our globe received its form as an oblate sphe- roid at a time when it existed throughout as a viscid mass. Nor is it unworthy of remark, that the same arrangement through which a fluid earth was moulded into this shape under the impulsion of the rotatory motion, also secured that when that earth came to be covered by a fluid sea, placed under the same impulsive influence, it should cling to it equably, like a well-fitted cloak, without falling off to the poles on the one hand, or accumulating in a belt round the equator at the other. But time fails, and I cannot follow up this subject to its legitimate conclusions. Allow me, therefore, simply to state, that I must continue to hold, with Humboldt and with Hutton, with Play fair and with Hall, that this solid earth was at one time, from the centre to the circumfer- ence, a mass of molten matter. Let us remember I employ here the words of Humboldt that the great chemist Sir Humphrey Davy, to whom we are indebted for the knowledge of the most combustible metallic sub- stances, renounced his bold chemical hypothesis in his last work ("Consolations of Travel"), as "inadequate and un- tenable ;" and further, that, with the oblate sphericity of the earth and the planets to be accounted for, those who continue to hold what he rejected, will be reduced, if they persist, to the unphilosophical necessity of regarding as a consequence of miracle, a peculiarity of shape easily ex- plainable on the principles of known law. Now, the fact of a molten earth involves a long series of LECTURES ON GEOLOGY. 297 conditions, each different from all the others, and from the conditions of the present time. It involves the existence of a period in the 'history of our planet when life, animal or vegetable, was not, and of a succeeding period, when life began to be. It involves, too, the ripening of the earth, from ages in which its surface was a thin, earthquake-sha- ken crust, subject to continual sinkings, and to fiery out- bursts of the plutonic matter, to ages in which it is the very nature of its noblest inhabitant to calculate on its stability as the surest and most certain of all things. It involves, in short, those successive conditions of life in the geologic ages, which, in connection with what is now Scot- land, I have, I am afraid, all too inadequately attempted to set before you in my present course. In fine, the primary rocks, when they underlie to a great thickness, as in our own country, the Paleozoic deposits, I regard as the de- posits of a period in which the earth's crust had sufficiently cooled down to permit the existence of a sea, with the necessary denuding agencies, waves and currents, and, in consequence, of deposition also ; but in which the internal heat acted so near the surface, that whatever was deposited came, as a matter of course, to be metamorphosed into semi-plutonic forms, that retained only the stratifica- tion. I dare not speak of the scenery of the period. We may imagine, however, a dark atmosphere of steam and vapor, which for age after age conceals the face of the sun, and through which the light of moon or star never pene- trates ; oceans of thermal water, heated in a thousand cen- tres to the boiling point ; low, half-molten islands, dim through the fog, and scarce more fixed than the waves themselves, that heave and tremble under the impulsions of the igneous agencies ; roaring geysers, that ever and anon throw up their intermittent jets of boiling fluid, va- 298 LECTURES ON GEOLOGY. por, and thick steam, from these tremulous lands ; and, in the dim outskirts of the scene, the red gleam of fire, shot forth from yawning cracks and deep chasms, and that bears aloft fragments of molten rock and clouds of ashes. But should we continue to linger amid a scene so featureless and wild, or venture adown some yawning opening into the abyss beneath, where all is fiery and yet dark, a soli- tary hell, without suffering or sin, we would do well to commit ourselves to the guidance of a living poet of true faculty, Thomas Aird, and see with his eyes, and describe in his verse : " The awful walls of shadows round might dusky mountains seem, But never holy light hath touched an outline with its gleam; 'T is but the eye's bewildered sense that fain would rest on form, And make night's thick blind presence to created shapes conform. No stone is moved on mountain here by creeping creature crossed, No lonely harper comes to harp upon this fiery coast; Here all is solemn idleness; no music here, no jars, Where silence guards the coast ere thrill her everlasting bars; No sun here shines on wanton isles; but o'er the burning sheet A rim of restless halo shakes, which marks the internal heat; As in the days of beauteous earth we see, with dazzled sight, The red and setting sun o'erflow with rings of welling light." NOTE. "The only shells I ever detected in the brick-clay of Scotland occurred in a deposit in the neighborhood of St. Andrew's, of apparently the same age as the beds at Portobello." Lecture Secontl, page 106. NOTE. Some time after this statement was made, Mr. Miller devoted himself to a farther investigation of the brick-clay beds in the neighborhood of Porto- bello, and discovered several species of shells in situ, especially great abundance of Scrobicularia piperata which he has described in a paper on the brick-clays, to be published hereafter. They form a very interesting portion of his Museum, now in the University of Edinburgh. " But for him," said an accomplished geologist, in talking with me on the subject, " we would have known nothing whatever of the brick-clays." I* M. DESCEIPTIVE SKETCHES FROM A GEOLOGIST'S PORTFOLIO. DESCRIPTIVE SKETCHES FROM GEOLOGIST'S PORTFOLIO. GANOID SCALES AND RAYS. THE scales of the ganoid order consist of three plates, an inner, an outer, and an intervening one. The outer is composed mainly of enamel, and retains, when entire, however long exposed, much of the original dinginess of hue which it bore in the quarry. The inner is a plane of porcelanic-looking bone. The intermediate plate is finely composed of concentric lines, crossed from the centre to the circumference by finely radiating ones ; and when, as mostly happens, this middle plate is exposed, the appear- ance of a mass of scales through the glass is of groat beauty. The rays of our soft-finned fish, (Malacopterygii), such as the haddock, seem as if cut through at minute dis- tances, and then reunited, though less firmly than where the bone is entire, with the design, it would seem, of giv- ing to the organs of motion which they compose, the nec- essary flexibility, somewhat on the principle that a carpen- ter cuts half-through with his saw the piece of moulding which he intends bending along some rounded corner, or forcing into some concave. But in the ancient ganoid 26 302 DESCRIPTIVE SKETCHES FROM fish, in which the rays are bare enamelled bones, and nec- essarily of great rigidity, the joints appear real, not ficti- tious. We see them cut across into short lengths, a single fin consisting of many hundred pieces ; and the problem lay in conceiving how such a fin was to be wrought, whether, for instance, each detached length was to have its moving ligament ; and if so, how a piece of machinery so very complicated and multifarious was to be set and kept in motion. Here, however, I found the problem very simply resolved. The rays of the ganoid fish, like its scales, consist of three plates, two plates of enamel, one on each side, and an interior plate of bone. Now the joints, though so well marked, that in rays imbricated on the sides, as in those of the Cheirolepis, the imbricated markings turn the corners, if one may so speak, just as the carvings on a moulding recounter, as a workman would say, at the corners of a building, are not real joints after all : they reach but through the inflexible enamel, leaving the central plate of bone undivided. Like the rays of the Malacopterygii, they are formed on the principle of the half-sawn moulding. I observed, too, that the inner plate is in every instance considerably narrower than the plates of enamel which rest upon it. In the lateral edges of every ray which composes the inner portion of the fin there must exist a groove, therefore ; and in this groove, it is probable, 'the connecting membrane at one time lay hid, performing, like an invisible hinge, its work unseen. RECENT BONE-BED IN THE FORMING. I ONCE found an interesting illustration of the bone- bed, coupled with at least one of the causes to which it owes its origin, in the upper part of the Moray Frith. I A GEOLOGIST'S PORTFOLIO. 303 had been spending a night at the herring-fishing, on one of the most famous fishing-banks of the east coast of Scot- land, the bank of Guilliam. It is a long, flat ridge of rock that rises to within ten or twelve fathoms of the sur- face. On its southern edge there is a submarine valley that sinks to at least twice that depth ; and in the course of the night our boat drifted from off the rocky ridge, the haunt of the* herrings, to the deepest part of the valley, where scarce a herring is ever found. Our nets had, how- ever, brought fish with them from the fishing-ground, suf- ficient in quantity to sink them to the bottom of the hol- low ; and in raising them up, a work of some little exertion, we found them bedaubed with patches of a stinking, adhesive mud, that, where partially washed on the surface, seemed literally bristling over with minute fish-bones. The muddy bottom of the valley may be regarded as a sort of submarine burial-ground, an ex- tensive bone-bed in the forming. " What," we asked an intelligent old fisherman, "brings the fish here to die? Have you observed bones here before ?" " I have observed them often," he said: "we catch few herrings here; but in winter and spring, when the cold draws the fish from off the shallows into deep water, we catch a great many haddock and cod in it, and bring up on our lines large lumps of the foul bottom. In spring, when most of the small fish are sickly and out of season, and too weak to lie near the shore, where the water is rough and cold, they take shelter in the deep here, in shoals ; and thousands of them, as the bones testify, die in the mud, not because they come to die in it, but just because their sickly season is also their dying season." And such seemed to be the true secret of the accumulation. The fish resorted to this place of shelter, not in order that they might die, but that 304 DESCRIPTIVE SKETCHES FROM they might live ; just as people go to poor-houses and hospitals with a similar intention, and yet die in them, at times, notwithstanding. And hence, I doiibt not, in most instances those accumulations of fish-bones which men accustomed to the use of the trawl-net find in detached spots of bottom, when in other parts, not less frequented by fish in the milder seasons, not a single bone is to be found, and which have been described as 'dying places. The dying places, the deep burial-grounds of the sea's finny inhabitants, will be found, almost always, to prove their places of shelter. And hence, it is probable, many of the bone-beds of the geologist. DIPTEKUS MACROLEPIDOTUS ABUNDANT IN THE BANNISKIRK OLD RED OF CAITHNESS. Let the reader imagine a fish delicately carved in ivory, and then crusted with a smooth shining enamel, not less hard than that which covers the human teeth, but thickly dotted with minute puncturings, as if stippled all over with the point of a fine needle; let him imagine the enamelled rays lying so thickly in the fins, that no con- necting membrane appears, and that each individual ray consists of numerous pseudo-joints, so rounded at their terminations, that each joint seems a small oblong scale, or each ray, rather, a string of oval beads ; in due har- mony with the rounded joints, let him imagine the scales of a circular form, and so regularly laid on, that the ruler ranges along them in three different ways, from head to tail, parallel to the deeply-marked lateral line, and in slant angles across the body ; immediately under the gill- covers, which consist, as in the sturgeon, of but a single plate a-piece, let him imagine two strong pectoral fins of A GEOLOGIST'S PORTFOLIO. 305 an angular form, with an interior angle in each covered with small scales, and the rays, as in the case of the tail, forming but a fringe around it ; let him imagine the ven- tral fins, which lie far adown the body, of an exactly simi- lar pattern, angular projections covered with scales in the centre, and fringed on two of their edges with rays ; exactly opposite to these, let there occur an anterior dorsal fin of comparatively small size, and then exactly opposite to the anal fin a posterior dorsal of at least twice the size of the other; let the anal fin be also large and sweeping, extending for a considerable way under the tail, which must like the tails of all the more ancient fish, be formed mainly on the under side, the vertebral column running on to its termination ; and the fish so formed will be a fair representation of the ancient Dipterus. Pre- senting externally in its original state no fragment of skin or membrane, and with even its most flexible organs sheathed in enamelled bone, it must have very much re- sembled a fish carved in ivory. What chiefly struck me in the examination was the peculiar structure of the ven- tral fins, the hind paws of the creature, if I may so speak. Their internal angle of scales imparts to them an appearance of very considerable strength, such an ap- pearance as that presented by the hind fins of the Ichthy- osaurus, which, as shown by a lately-discovered specimen, were furnished on the outer edges with a fringe of cartila- ginous rays ; and I deemed it interesting thus to mark the true fish approximating in structure, ere the reptilia yet existed, to the reptile type. The young frog, when in its transition state, gets its legs fully developed, and yet for some little time thereafter retains its tail. The Dipterus seems to have been a fish formed on this sort of transition plan. 26* 30t> DESCRIPTIVE SKETCHES FROM FOSSIL-WOOD OF THE OOLITE AT HELMSDALE, SUTHERLAND. What first strikes the observer in the appearance of the fossil-wood of this coast is the great distinctness with which the annual layers are marked. The harder lines of tissue, formed in the end of autumn, stand out as dis- tinctly on the weathered surfaces as we see them in pieces of dressed deal that have been exposed for a series of years to the light and the air. The winters of the Oolitic period in this northern locality must have been sufficiently severe to have given a thorough check to vegetation. We are next struck by the great inequality of size in these layers, as we find them shown in separate specimens. I brought with me one specimen in which there is a single layer nearly half an inch in breadth, and another in which, in no greater space, there occur fourteen different layers. The tree to which the one belonged must have been in- creasing in bulk fourteen times more rapidly than that of the other. Occasionally, too, we find very considerable diversities of size in the layers of the same specimen. One year added to its bulk nearly half an inch ; in another it increased scarce an eighth part. Then, as now, there must have been genial seasons, in which there luxuriated a rich-leaved vegetation, and other seasons of a severer cast, in which vegetation languished. My microscope, a botanist's, was of no great power ; but by using its three glasses together, and carefully grinding down small patches of the weathered wood till it began to darken, I could as- certain with certainty, from the structure of the cellular tissue, what, indeed, seemed sufficiently apparent to the naked eye from the general appearance of the specimens, that they all belonged to the coniferae. When viewed longitudinally, I could discern the elongated cells lying A GEOLOGIST'S PORTFOLIO. 307 side by side, and the medullary rays stretching at right angles across; but my glass lacked power to show the glandular dots. When viewed transversely the regularly reticulated texture of the conifers was very apparent. A bluish-gray limestone adhered to some of the specimens, and bore evidence in the same track. It abounded in cones and fragments of cones, in what seemed minute needle-shaped leaves, and in thin detached pieces of bark, like those which fall off in scales from the rind of so many of the coniferse. The limestone bore also its fre- quent fragments of fern. There seemed nothing lacking to restore the picture. There rose before me a solemn forest of pines, deep, shaggy, and sombre; its opening slopes and withdrawing vistas were cheered by the lighter green of the bracken ; and far beyond, where the coast terminated, and the feathery tree-tops "were relieved against the dark blue of the sea, a long line of surf tumbled inces- santly over a continuous reef of coral. I picked up one very fine specimen, which, though it weighed nearly a hundred weight, I resolved on getting transported to Edinburgh, and which now lies on the floor before me. It is a transverse cut of a portion of a large tree, including the pith, and measures twenty-three inches across. In the sections of trees, figured by Mr. Witham in his interesting and valuable work, the original struc- ture seems much disorganized: a granular radiating spar occupies the greater portion of the interior ; and the tissue is found to exist in but detached portions. Here, on the contrary, the tissue exists unbroken from the pith to the outer ring. We may see one annual circle succeeding another in the average proportion of about ten per inch ; and though we cannot reckon them continuously, foi* there are darker shades in which they disappear, shades 308 DESCRIPTIVE SKETCHES FROM which the polisher of the marble-cutter may yet succeed in dissipating, the number of the whole must rather exceed than fall short of a hundred. However obscure the geologist may be in his eras generally, here at least is the record of one century. But how were its years filled ? I sat beside the root of a newly-felled fir some six or eight seasons ago, and amused myself, when the severed vessels were throwing up their turpentine in minute transparent globules, in reckoning the years by the rings, from the bark inward. Here, I said, is the year in which the Re- form Bill passed ; and this the year in w r hich Canning died ; and this the year of the great commercial crisis ; and this the year of Waterloo ; and this of the burning of Moscow. The yearly rings of the Oolite have no such indices of recollection attached to them: we see their record in the markle, but know no more of contemporary history than that, when forests showed their fringes of lighter green on the hill-sides, and cell and fibre swelled under the rind, the promptings of instinct were busy all around and beneath, that the pearly ammonite raised its tiny sails to the breeze, as the belemnite, with its many arms, shot past below, that nameless birds mingled with flying reptiles, and that, while the fierce crocodile watched in his pool for prey, the gigantic iguanodon stretched his long length of eighty feet in the sand. But who shall reveal the higher history of the time? The reign of war and of death had commenced long before ; and who shall assert that moral evil had not long before cast its blighting shadows over the universe, that there had not been that war in heaven in which the uncreated angel had overthrown the dragon, or that unhappy intel- ligences did not wander, "seeking rest, but finding none," in an earth of " waste places," whose future sovereign still lay hid in the deep purposes of Eternity ? A GEOLOGIST'S PORTFOLIO. 309 ASTREA OF THE OOLITE, SUTHERLAND. The same deposit in which I found the wood embed- ded, contains large masses of coral, all apparently of one species, not a branching coral, but of the kind which, consists of large stone-like masses covered on the surface with stellular impressions, framed in polygons, and which composes the genus Astrea. I picked up one very fine specimen, which I have since got cut through and pol- ished. It presents a polygonal partitioning, of a delicate cream-color, that somewhat resembles the cells of a honey- comb. Each cell is filled with a brownish ground of car- bonate of lime ; and on this ground of brown there is a cream-colored star, composed of rays that proceed from the centre to the sides. One of these corals measured two feet and a half across in one direction, by two feet in another ; and if it grew as slowly as some of its order in the present scene of things, its living existence must have stretched over a term of not less extent than that of its contemporary, the pine of the hundred rings. Some of the masses seem as if still adhering to the rocks on which they originally grew ; the pentagonal cells are still open, as if the inhabitants died but yesterday ; and the star-like lines inside still retain their original character of thin par- titions, radiating outwards and upwards from a depressed centre. In other instances they have been torn from their places, and He, upturned in the shale, amid broken shells and fragments of wood. I brought with me one curious specimen perforated by an ancient pholas. The cavity exactly resembles those cavities of the existing Lithodo- mus shell which fretted so many of the calcareous masses that lay scattered on the beach on every side; but it is shut firmly up by the indurated shale in which the speci- 310 DESCRIPTIVE SKETCHES FROM men itself had lain buried, and a fragment of carbonized Avood lies embedded in the entrance. The cave is cur- tained across by a wall of masonry, immensely more ancient than that which converted into a prison the cave of the Seven Sleepers. RECENT TYPES OF FOSSILS. An imagination curious to reerect and restore, finds assistance of no uninteresting kind among the pools and beneath the bunches of sea-weed which we find scattered, at the fall of the tide, over the surface of the Navidale deposits. One very minute pool of sea-water, scarcely thrice the size of a common washing basin, and scarcely half a foot in depth, furnished me with the recent types of well nigh all the fossils that lay embedded for several feet around it ; though there were few places in the bed where these lay more thickly. Three beautiful sea ane- mones two of crimson, and the third of a greenish-buff color stretched out their sentient petals along the sides; and the minute currents around them showed that they were all employed in their proper trade of winnowing the water for its animalcular contents, working that they might live. One of the three had fixed its crimson base on the white surface of a fossil coral ; the pentagonal cav- ities, out of each of which a creature of resembling form had once stretched its slim body and still /ninuter petals, to agitate the water with similar currents, were lying open around it. In another corner of the pool a sea-urchin was slowly dragging himself up the slope, with all his red fleshy halsers that could be brought to bear, and all his nearer handspikes hard strained in the work. His pro- gress resembled that of the famous Russian boulder, trans- A GEOLOGIST'S PORTFOLIO. 311 ported for so many miles to make a pedestal for the statue of Peter the Great; with this difference, however, that here it was the boulder itself that was plying the hand- spikes and tightening the ropes. And, lo ! from the plane over which he moved there projected the remains of creatures of similar type ; the rock was strewed with fossil handspikes, greater in bulk than his, and somewhat diverse in form, but whose general identity of character it was impossible to mistake. The spines of echini, fret- ted with lines of projections somewhat in the style of the pinnacles of a Gothic building, lie as thickly in this de- posit as in any deposit of the Chalk itself. The pool had its zoophytes of the arborescent form, the rock its flus- tra ; the pool had its cluster of minute muscles, the rock its scallops and ostrea ; the pool had its buccinidae, the rock its numerous whorls of some nameless turreted shell ; the pool had its cluster of serpula3 ; the serpulae lay so thick in the rock, as to compose, in some layers, no inconsiderable proportion of its substance. BRORA COAL-FIELD OTHER THAN THE TRUE COAL MEASURES. A coal-field in other than the true Coal Measures is always an object of peculiar interest to the geologist ; and the coal-field of Brora is, in at least one respect, one of the most remarkable of these with which geologists are yet acquainted. The seams of the well-known Bovey coal of South Devon a lignite of the Tertiary are described as of greater depth ; but it burns so imperfectly, and emits so offensive an odor, that, though used by some of the poorer cottagers in the neighborhood, and some of the local potteries, it never became, nor can become, an article of commerce. It is curious merely as an immense 312 DESCRIPTIVE SKETCHES FROM accumulation of vegetable matter passing into the mineral state, as, shall I venture to say, a sort of half-mineralized peat of the Tertiary, a peat moss that, instead of over- lying, underlies the diluvium. In the Brora coal, as might be inferred from its much greater age, the process of mineralization is more complete ; and it furnishes, if I mistake not, the only instance in which a coal newer than that of the carboniferous eja has been wrought for cen- turies, and made an article of trade. There were pits opened at Brora as early as the year 1598 : they were reopened at various intermediate periods in the seven- teenth and eighteenth centuries ; on one occasion in the middle part of the latter, by Williams, the author of a "Natural History of the Mineral Kingdom," which has been characterized by Lyell as " a work of great merit for its day ; " and during twelve years of the present century, from 1814 to 1826, there were extracted from but a single pit in this field no fewer than seventy thousand tons of coal. The Oolitic coal-field of Sutherland stands out in prominent relief amid the ligneous deposits that derive their origin from the later geological floras. And yet its commercial history does not serve to show that the specu- lations of the miner may be safely pursued in connection with any other than that one wonderful flora which has done so much more for man, with its coal and its iron, than all the gold mines of the world. The Brora work- ings were at no time more than barely remunerative; and the fact that they were often opened to be as often aban- doned, shows that they must have occasionally fallen somewhat below even this low line. Latterly, at least, it was rather the deficient quality of the coal that mili- tated against the speculation, than any deficiency in the quantity found. It burned freely, and threw out a pow- A GEOLOGIST'S PORTFOLIO. 313 erful flame; but it was accompanied by a peculiar odor, that seemed to tell rather of the vegetable of which it had been originally composed, than of the mineral into which it had been converted, and then sunk into a white l' ht ash, which every breath of air sent floating over carpets and furniture. And so, when brought into compe- tition, in our northern ports, with the coal of the Mid- Lothian and English fields, it failed to take the market. The speculation of Williams was singularly unlucky. He became lessee of the entire field about the year 1764, and wrought it for nearly five years. There occurs near the centre of the main seam a band of pyritiferous concre- tions, which here, as elsewhere, have the quality of taking fire spontaneously when exposed in heaps to air and mois- ture, and which his miners had not been sufficiently careful in excluding from the coal. A cargo which he had ship- ped from Portsoy, in BanfFshire, took fire in this way, in consequence, it has been said, of the vessel springing a leak ; and such was the alarm excited among his cus- tomers, that they declined dealing with him any longer for a commodity so dangerous. And so, after an ineffec- tual struggle, he had to relinquish his lease. LONDON MUSEUM OF ECONOMIC GEOLOGY. In the Museum of Economic Geology now in the course of forming in London, there are specimens exhibited of not only the various rude materials of art, furnished by the mine and the quarry, but also of what these can be converted into by the chemist and the mechanic. Not only does it show the gifts of the mineral kingdom to man, but the uses also to which man has applied them. The rough and unpromising block of marble stands side 27 314 DESCRIPTIVE SKETCHES FROM by side with the exquisitely polished and delicately-sculp* tured vase. The bracelet of glittering steel, scarcely of less value than if wrought in gold, ranges in striking con- trast with the earthy, umbry nodule of clay-ironstone. There are series of specimens, too, illustrative of the various changes which an earth or metal assumes in its progress through the workshop or the laboratory. Here, for instance, is the ironstone nodule, there the roasted ore, yonder the fused mass ; the wrought bar succeeds ; then comes the rudely-blocked ornament or implement; and, last of all, the exquisitely finished piece of work, as we find it in the cutler's warehouse or the jeweller's shop. I am not aware whether the museum also exhibits its sets of specimens illustrative of substances, elaborated, not by man, but by nature herself; and elaborated, if one may so speak, on the principle of serial processes and succeed- ing stages. The arrangement in many cases would have to proceed, no doubt, on a basis of hypothesis ; but the cases would also be many in which the hypothesis would, at least, not seem a forced one. It was suggested to me on the Brora coal-field, that the process through which nature makes coal might be strikingly illustrated in this style. One might almost venture to begin one's serial col- lection with a well-selected piece of fresh peat, containing its fragments of wood, its few blackened reeds, its fern- stalks, and its club-mosses. Another specimen of more solid homogeneous structure, and darker hue, cut from the bottom of some deep morass, might be placed second in the series. Then might come a first specimen of Bovey coal, taken from under its eight or ten feet of Tertiary clay, a specimen of light and friable texture, and that exhibited more of its original and vegetable qualities than of its acquired mineral ones. A second specimen, brought A GEOLOGIST'S PORTFOLIO. 315 from a deeper bed of the same deposit, might be chosen by the darker brown of its color, and its nearer "approxi- mation to the structure of pit-coal. The Oolitic coal of the Brora or Yorkshire field might furnish at least two specimens more. And thus the collector might pass on, by easy gradations, to the true Coal Measures, and down through these to the deeply-seated anthracite of Ireland, or the still- more deeply-seated anthracite of America, not altogether so assured of his arrangement, perhaps, as in dealing with the processes of the laboratory or the workshop, but at least tolerably sure that both chemists and naturalists would find fewer reasons to challenge than to confirm it. BRORA PEAT-MOSSES OF THE OOLITE. The Brora field, so various in its deposits, must have ex- isted in many various states, now covered by salt water, now by fresh, now underlying some sluggish estuary, now presenting, perchance, a superaqueous surface, dark- ened by accumulations of vegetable matter, and now, again, let down into the green depths of the sea. To real- ize such a change as the last, one has but to cross the Moray Frith at this point to the opposite land, and there see a peat-moss covered, during stream tides, by from two to three fathoms of water, and partially overlaid by a stratum of sea-sand, charged with its characteristic shells. It is a small coal-bed, kneaded out and laid by, though still in its state of extremest unripeness, a coal-bed in the raw material ; and there are not a few such on the coasts of both Britain and Ireland. Professor Fleming's description of the submerged forests of the Friths of Forth and Tay must be familiar to many of my readers. 316 DESCRIPTIVE SKETCHES FROM They must have heard, too, through the far-known "Prin- ciples " .of Lyell, of the submerged forests of Lancashire. "In passing over Slack Sod Bay, in a clear, calm morn- ing," says a late tourist in Erris and Tyrawly, "I could see, fathoms down, the roots of trees that seemed of the same sort as are every day dug out of our bogs." Now, we do not know that the Oolite had properly its peat- mosses. The climate, though its pines had. their well- marked annual rings, seems, judging from its other pro- ductions, to have been warmer than those in which peat now accumulates ; but there can be no doubt that both it and the true Coal Measures must have had their vast accumulations of vegetable matter, formed, in many in- stances, on the spot on which the vegetable matter grew ; and no one surely need ask a better definition of a peat- moss. A peat-moss, in the present state of things, is sim- ply an accumulation of vegetable matter formed on the spot on which it grew. These, as I have said, we fre- quently find let down on our coasts far beneath the sea- level, and covered up by marine deposits ; and the fact furnishes a first and important step in the proposed serial arrangement of coal in the forming. May I not further add, that Professor Johnston, of Durham, so well known in the field of geological chemistry, regards all our coal- seams, whether of the Carboniferous period or of the Oo- litic, as mere beds of ancient peat, mineralized in the labo- ratory of Nature ? QUARRY OF BRAAMBURY UPPER OOLITE, SUTHERLAND. On entering the quarry hollowed on the southern emi- nence, one is first struck by the character of the broken masses of stone that lie scattered over the excavations. A GEOLOGIST'S PORTFOLIO. 317 The rubbish abounds 'in what seem fragments of a very exquisite sculpture. The shells and lignites, which it con- tains in vast numbers, exist as mere impressions in the white sandstone, and look as if fresh from the chisel of a Thorn or Forrest. But even these masters of their art would confess themselves outdone here in beauty of finish. Their best works don't stand the microscope ; whereas the carvings of the Upper Oolite here, though in sandstone, mightily improve under it. The cast of a broken frag- ment of wood at present before me shows not only the markings of the annual rings, but also the microscopic stria3 of the vegetable fibre, a niceness of impression impossible in any sandstone that had not what the sand- stones of this quarry have, a large mixture of calcare- ous cement. I remember that, on my first introduction to the excavations of Braambury, for such is the name of the quarry, the vast amount of what seemed broken sculpture in the rubbish reminded me of some of Ten- nant's singularly happy descriptions in his "Dingin down o' the Cathedral." They seemed mememorials of a time when, to the signal detriment of ecclesiastical architecture in Scotland, and all the good solid religion that springs out of sandstone, " Hk tirlie-wirlie mament bra, That had for centuries ane and a' Brankit on bunker or on wa', Cam tumblin tap o'er tail * * Whan in ilk kirk the angry folk Carv't wark, an arch, an pillar broke." I had not a few other recollections of the quarry of Braambury. Nothing can be more interesting to the geol- ogist than its fossils, and nothing more annoying, at times, to the workman. Occurring often in the wrought stone, they occasion sad gaps and deplorable breaches, where the 27* 318 DESCRIPTIVE SKETCHES FROM plane should be smooth or the moulding sharp. I remem- ber laying open, on one occasion, a beautiful cast that had once been a belemnite, but that had become a mere cavity in which a belemnite might be moulded, for even this solid fossil, that so doggedly preserves its substance in most other deposits, is absorbed by the sandstone of Braambury. And greatly did I admire its peculiar state of keeping. The smooth, cylindrical hollow was partitioned across by two stony diaphragms, thin as bits of drawing- paper; for ere the absorbing-process had begun, the fossil had been broken into three pieces by the superincumbent weight, and the minute strips of sand which had filled up the cracks had hardened into stone. The point was sharp and smooth ; a rectilinear convex ridge showed the place of the abdominal groove ; a cone at the base, lined trans- versely, represented the chambered shell of the interior. There could not be a more interesting specimen for a museum ; but, alas ! it occupied the polished plane of a tombstone, just where the hicjacet should have been ; and though it symbolized the sentence wonderfully well, it was a symbol which I feared few would succeed in interpreting. I pointed it out to a brother workman. "Ah," said he, "you have got one of these terrrible tangle-holes; they're the dash'dest things in all the quarry." Many a curious thing besides does this quarry contain : boles of trees, that look as if sculptured in the white sand- stone, with their gnarled and twisted knots and furrowed rinds ; striated reeds of the same brittle material, that seem the fluted columns of architectural models ; club- mosses, with their gracefully-disposed branches; rounded stems, scaled like the cones of the fir ; impressions of fi- brous, sword-shaped leaves, that resemble the leaves of the iris ; and the casts of fragmentary masses of timber, A GEOLOGIST'S PORTFOLIO. 319 deeply fretted by the involved and tortuous gnawings of some marine worm. Such are a few of the sculptured representations of the flora of the period, things more delicate by a great deal than those carved flowers of Mel- rose which we find described with such picturesque effect by Sir Walter. And its fauna we see represented quite as interestingly as its flora. Its sculptured Pectens remind us of those of a Grecian frieze ; a beautifully-ribbed Cardium has proved a still finer subject for the chisel; its Gryphites stand out in the boldest style of art. One very striking Ammonite (Ammonite perarmatus) exhibits a double row of prominent cones, that run along the spiral windings, and give to it the appearance of an Ionic volute inge- niously rusticated ; and another Ammonite, that takes its name from the quarry (Ammonite JBraamburiensis)^ pre- sents on its smooth, broad surface, for in form it resem- bles some of our recent nautili, the gracefully-involved lines of the internal partitioning, as sharp and distinct as if traced on copper by the burin. The traveller explores and examines, and finds the rude excavation on the hill- side converted into the studio of some wonderful sculptor. In the quarry opened on the other eminence there are similar appearances presented, but the stone is softer, and the impressions less sharp. GLACIERS AND MORAINES OF SUTHERLAND. Let vis mark the abrupt and imposing character of the hills. They rise dark, lofty, and bare, and show to em- ploy a graphic Highland phrase their bones sticking through the skin. They must have been well swept, surely ; and as they are composed mainly of Old Red Sandstone conglomerate in this locality, for we have left 320 DESCRIPTIVE SKETCHES FROM behind us the granitic hills of Navidale and Loth, their sweepings, could we but find them, would have, doubtless, a well-marked character. And now let us turn to appear- ances of another kind. We stand on the polished surface of the rock, with its rectilinear grooves and scratches, and, when we look upwards along the lines, see the mountains and the valley ; but what see we when we look downwards along the lines? Something exceedingly curious indeed; double and triple ranges of miniature hills, composed of boulders and gravel, the veritable conglomerate sweepings of the mountain-slopes and the valley, mixed with sweep- ings of the more distant primary hills that rise behind. There they lie, in lines that preserve such a rude parallel- ism to the steep range from which they were originally scraped, as the waves that rebound from a seaward barrier of cliff maintain to the line of the barrier. Varying from thirty to forty feet in height, and steep and pyramidal, in the cross section, as roofs of houses, they run in contin- uous undulating lines of from a hundred yards to half a mile in length. Three such lines, with their intervening valleys, occur between the base of Braambury Hill and the village of Brora, like inner, outer, and middle mounds of circumvallation in an ancient hill-fort. If one steadily rakes, with the edge of one's moist palm, the scattered crumbs on a polished tea-table, they form, of course, into irregular lines, presenting in the transverse section a rudely angular form ; and in the direction in which they have been swept, the moisture from the palm furrows the mahogany with minute streaks of dimness. The illustra- tion is one on the smallest scale possible. But if the palm be tolerably moist, the crumbs tolerably abundant, and the polish of the mahogany brought brightly out, and if we rake into rude parallelism in this way, line after line from A GEOLOGIST'S PORTFOLIO. 321 the front of some platter or bread-dish, upturned to repre- sent the line of hills, we shall have provided ourselves with no very inadequate model of the phenomena of Braam- bury. But what palm of inconceivable weight, breadth, and strength, could have been employed here in thus raking the debris into lines of hills half a mile in length by at least thirty feet in height, and in pressing into smoothness, as it passed, the asperities of the solid rocks below? The reader has already anticipated the reply. We have before us indications of an ancient glacier, the most unequivocal that are to be found, perhaps, anywhere in the kingdom : there is not a condition or accompani- ment wanting. I have had my doubts regarding glacial agency in Scotland; but, after visiting this locality a twelvemonth ago, I found doubt impossible ; and I would now fain recommend the skeptical to suspend their ulti- mate decision on the point, until such time as they shall have acquainted themselves with the grooved and polished rocks of Braambury, and the parallel moraines that stretch out around its base. I had lacked time, during my visit of the previous sea- son, to examine the moraines that lie in the opening of the valley higher up, and now set out to explore them. The day had become exceedingly pleasant. A few cottony- looking wreaths of mist still mottled the hills, and the sky overhead was still laden with clouds ; but ever and anon the sun broke out in hasty glimpses, that went flashing across the dark moors, now lighting up some bosky recess or abrupt cliff, now casting into strong prominence some insulated moraine. The hollow between Braambury and the hills is occupied, as I have said, by an extensive mo- rass, in which the inhabitants of the neighborhood dig their winter fuel, and which we find fretted, in conse- 322 DESCRIPTIVE SKETCHES FROM quence, by numerous rectilinear cavities, filled with an inky water, and roughened and darkened on its drier swellings with innumerable parallelograms of peat. I passed an opening in which there were no fewer than five gnarled, short-stemmed fir-trees, laid bare. They lay clustered to- gether, as if uprooted and thrown down by some tremen- dous hurricane, presenting exactly such appearances as I have seen in the woods of Cromarty after the hurricane of November 1830, when, in less than an hour, three thou- sand full-grown trees were blown down in one not very extensive wood, and lay heaped on some of the more ex- posed eminences in groups of six and eight. A few hun- dred yards from the prostrate trees there rises, amid the morass, a solitary moraine. I could see its gravelly root extending downwards under the peat, which, in the slow course of ages, had accumulated around it, and found the conviction pressing upon me, that, many centuries ago, when the five prostrate pines were living denizens of the forest, and the moss which now enveloped them had not formed, this insulated hill must have raised its heathy ridge over the trees, and borne the marks of an antiquity apparently not less remote than those which it bears now. And then, long ere the hill itself had formed, the same re- mark must have applied, with at least equal force, to the Oolitic rock below. We see that, when overlaid by the ponderous ice, it must have been exactly the same sort of hard, brittle sandstone it is at the present moment. As shown by the slim partitionings that divide internally its casts of Belemnites, it must have hardened ere its fossils were absorbed ; and, as shown by its polished and striated surfaces, its fossils must have been absorbed ere the glacier slid over it. "We see laid bare in the lines of the striae, the casts of Gryphites, Pectens, and Terebratula; we see, A GEOLOGIST'S PORTFOLIO. 323 further, that the hollows which they formed were weak places in the stone, and that the ice, breaking through, had crushed into them the minute fragments of which their roofs had been composed ; and so infer, from the appear- ances, that the newer Oolite of Sutherland must have been as firm a building-stone in the ages of the glaciers as it is now. As we approach the valley of the Brora, we see a long, well-marked moraine sweeping in a curved line along the base of the hill that forms its northern boundary of en- trance, and are again reminded, by the general parallelism of moraine and hill, of the reversed wave thrown back from a barrier of rock. In the gorge of the valley, immediately below where the river expands into a fine wild lake, we find the moraines very abundant, but preserving no regu- larity of line. They exist as a broken, cockling sea of miniature hills ; and, to follow up the twice-used illustra- tion, remind one of rebounding waves at the opening of a rocky bay, where the lines meet and cross, and break one another into fragments. Like many of the other moraines of the Highlands, they were of mark enough to attract the notice of the old imaginative Celtaa, who called them Tom- hans, and believed them to be haunts of the fairies, dom- iciles whose enchanted places of entrance might be discov- ered on just one night of the year, but which no man, not desirous of becoming a denizen of fairyland, would do well to enter. The lake above is a fine, lonely sheet of water, fringed with birch, and overlooked by many a green, unin- habited spot, dimly barred by the plough. A range of stern, solemn-looking hills rise steep and precipitous on either hand ; while a single picturesque hill, with abrupt sides and a tabular summit, terminates the upward vista some six or eight miles away. I saw in one reedy bay a 324 DESCRIPTIVE SKETCHES FROM whole community of water-lilies opening their broad white petals and golden stamens to the light ; and, wishing to possess myself of one that grew nearer the shore than any of the others, and having no such companion as Cowper's dog Beau to bring it me, I cut a long switch of birch, and struck sharply at the stem, that I might decapitate it, and then steer it to land. But the blow, though repeated and re-repeated, fell short ; and I had drawn my last, when up there started from the bottom a splendid lily, tAvo-thirds developed, a true Venus, that, rising from the water, looked up to the light, neck-deep, with the rest. The agi- tation occasioned by the strokes had burst the calix, and, true to its nature, up the prematurely-liberated flower had sprung. The image which the incident furnished mingled curiously with my attempted restorations of the ancient state of the valley. The delicate lily, rising to the surface in its quiet, sheltered bay, during a bright glimpse of sun- shine, formed an interesting point of contrast to what seemed a vast foaming river of ice, that rose on the hill- sides more than half their height, and swept downwards, till where it terminated in the plain, in an abrupt moving precipice, that ploughed before it, in its irresistible march, huge hills of gravel and stone. LEVEL STEPPES OF KUSSIA, AND THEORY OF MORAINES. In the level steppes of Russia, where the traveller may journey without seeing a hill for weeks together, the rocks have their grooved and polished surfaces. And even in localities where there are hills, the hills not unfrequently merely add to the difficulty. The lofty top of Schehallien, for instance, is grooved and polished ; and, pray, from what neighboring eminence could the glacier have descended on it? Extreme, however, as the difficulties that environ the A GEOLOGIST'S PORTFOLIO. 325 phenomena may seem, they have been manfully met by Agassiz, and dealt with in a style in which only a man of genius could have dealt with anything. And if difficulties still attend his theory, there are at least other difficulties which it ingeniously obviates ; and it seems but right, at all events, to give it generous entertainment and a fjiir trial, until such time as it may be found untenable, or until at least something better turns up to set in its place. The flat steppes of Russia have, I have said, their groov- ings and polishings : they have also their moraine ; and so enormous is the extent of the latter, that for week after week the traveller may find it stretching through the cen- tral wilds of the empire, on and on, without apparent ter- mination, by North Novogorod towards Pinsk, as far as the confines of Silesia. It exists as a broad belt of erratic blocks, mingled with heaps of gravel, and resembles, from its linear continuity, the scattered remains of some such vast wall as that which protected of old the Chinese fron- tier from the Tartar. And here, says Agassiz, is the mo- raine of a glacier that had for its centre no group of local eminences, no vanished Alps of the Frozen Ocean, but the North Pole itself. The ice of the Southern Pole advances as far. Could we but reverse the conditions of the two poles, the northern icy barrier would extend to the English Channel, and the whole British islands would lie enveloped in one vast glacial winding-sheet, that, overlying the sum- mits of our hills, would furrow with its parallel striae even the granitic top of Schehallien. A complete reversal of the conditions of the two poles would account, doubtless, for many of the phenomena existing in connection with the boulder-clay, which seem otherwise so inexplicable. But is the reversal itself pos- sible ? A Laplace or Lagrange could perhaps answer the 28 326 DESCRIPTIVE SKETCHES FROM question. This much, however, men of lower attainments may know, that the meteorological condition of the two poles are very different, the icy barrier advancing, in the case of the one, many degrees nearer the equator than it does in the case of the other ; that their astronom- ical condition is also very different, the sun being many millions of miles nearer the one in winter, and nearer the other in summer. It may be known, further, that these astronomical conditions are in a state of gradual change ; that, so far at least, as human observation extends, the change has been steadily progressing in one direction ; that, should it but continue, a time must inevitably arrive when their astronomical circumstances shall be wholly re- versed, a time when the sun shall look down upon our northern hemisphere in aphelion in winter, and in perihe- lion in summer. True, we do not yet know that the me- teorological differences of the poles depend on their astro- nomical differences, or whether the gradual diminution in the eccentricity of the earth's orbit, which has been lessen- ing these latter differences ever since astronomers regis- tered their observations, may not be like the change in the ecliptic, the result of mere oscillation, limited to a few degrees. Let us, however, conclude the case to be otherwise : let us deem the oscillations in the earth's orbit to be so great as to involve an alternate progress in the sun, between his two foci; let us further infer a dependence between his place in each and the meteorological condition of the poles. We stand, let us suppose, on the summit of a hill ; but, as if an immense wedge had been thrust between our feet and the soil, we rise to a higher elevation on an in- clined plane of ice, and look over a frozen continent, enlivened by no winding arms of the sea, and bounded by no shore. In the words of Coleridge, A GEOLOGIST'S PORTFOLIO. 327 " The ice is here ; the ice is there ; The ice is all around ; It cracks, and growls, and roars, and howls, A wild and ceaseless sound." It is summer; and the sun, in perihelion, looks down with intense glare on the rugged surface. There is a ceaseless dash of streams that come leaping from the more exposed ridges, as they shrink and lessen in the heat, or patter from the sunlit pinnacles, like rain from the eaves of a roof in a thunder-shower. They disappear in cracks and fissures; and we may hear the sound, rising from where they break themselves, far beneath, in chill caverns and gloomy re- cesses, where, even at this season, at noon, the tempera- ture rises but little above the freezing-point, and sinks far beneath it every evening as the sun declines. The night shall scarce have come on when all these water-courses shall be bound up by the frost, and the melted accumula- tions which they precipitated into the fissures beneath shall be converted into expansive wedges of ice, under the influence of which the whole ice-continent shall be moving slowly onwards over the buried land. Millions of millions of wedges shall ply their work during the night on every square mile of surface, and the coming day shall prepare its millions of millions more. There is thus a slow but steady motion induced towards the open space where the huge glacier terminates ; the rocks far below grind down into a clayey paste, as the ponderous mass goes crushing over them, deliberate, when at its quickest, as the hour- hand of a time-piece, and vast fragments are borne away from submerged peaks and precipices by the enclasping solid, just as ordinary streams bear along their fragments of rock and stone from the banks and ridges that lie most 328 DESCRIPTIVE SKETCHES FROM exposed to the sweep of their currents. All around, ac- cording to Milton, " A frozen continent Lies dark and wild, beat by perpetual storms." Not a peak of our higher hills appears : all are enveloped in their cerements of cold and death. Even along the flanks of the gigantic Alps, the groovings and polishings rise, says Agnssiz, to an elevation of nine thousand feet ; and then, and not before, do we find the pinnacles that overlooked the scene standing up sharp and unworn. If we ask a varied prospect, we must remove from our pres- ent stand, to where Mont Blanc and his compeers raise their white summits over the line of the horizon, to give earnest of a buried continent, or to where the smoke and fire of Hecla ascends amid the level from a dripping crater of ice. CROMARTY. Cromarty, my own especial manor, which I have so often beat over, but not yet half exhausted, presents to the geologist one of the most interesting centres of explor- ation in Scotland. Does he wish thoroughly to study our Scotch Lias, Upper and Lower, with the Oolitic member which immediately overlies it? then let him remove to Cromarty, and study it there. Is he solicitous to acquaint himself with the fossils of the Lower 1 Old Red Sandstone in that state of finest preservation in which the microscope finds most of beauty and finish in them ? then let him by all means settle at Cromarty. Is he wishful of know- ing much about the last elevated of our granitic hill i Now ascertained to be Middle. A GEOLOGIST'S PORTFOLIO. 329 ranges, a range newer, apparently, than many of our south-country traps? let him not hesitate to take lodg- ings at Cromarty. Is he curious regarding our boulder- clay ? let him set himself carefully to examine the splen- did sections which it presents in the neighborhood of Cromarty. Does he feel aught of interest in our raised beaches ? then let him come and live upon one at Cro- marty. Is he desirous of furnishing himself with a key to the geology of the north of Scotland generally? in no place will he be able to possess himself of so complete a key as among the upturned strata of Cromarty. Had he to grope his way along a course of discovery, he might find the district yielding up its more interesting phenom- ena but slowly. To know its Lias deposits thoroughly would be a work of months, and to know its Old Red Sandstone, a work of years ; but with some intelligent guide to point out to him the localities to which his atten- tion should be directed, and all in them that has been done and observed already, he would find that much might be accomplished in the course of a single week, especially in the long calm days of July, when the more exposed shores of the district, with all their insulated stacks and ledges, and all their deep-sea caves, may be explored by boat. CAVES OF CROMARTY, OR THE ART OF SEEING OVER THE ART OF THEORIZING. We swept ownwards through the noble opening of the Cromarty Frith, and landed under the southern Sutor, on a piece of rocky beach, overhung by a gloomy semi- circular range of precipices. The terminal points of the range stand so far out into the sea, as to render inacces- 28* 330 DESCRIPTIVE SKETCHES FROM sible, save by boat, or at the fall of ebb in stream tides, the piece of crescent-shaped beach within. Each of the two promontories is occupied by a cave in which the sea at flood stands some ten or twelve feet over the gravel bottom, and there are three other caves in the semicircle, into which the tide has not entered since it fell back from the old coast line. The larger and deeper of the three caves in the semicircular inflection is mainly that which we had landed to explore. It runs a hundred and fifty feet into the granitic rock, in the line of a fault that seems first to have opened some eight or ten feet, and then, lean- ing back, to have closed its sides atop, forming in this way a long angular hollow. It has borne for centuries the name of the Doo-cot, i. e. Dove-cot, Cave, and has been from time immemorial a haunt of pigeons. We approach the opening. There is a rank vegetation springing up in front, where the precipice beetles over, and a small stream comes pattering in detached drops like those of a thunder- shower; and we see luxuriating under it, in vast abun- dance, the hot, bitter, fleshy-leaved scurvy-grass, of which Cook made such large use, in his voyages, as an anti-scor- butic. The floor is damp and mouldy ; the green ropy sides, which rise some five-and-twenty feet ere they close, are thickly furrowed by ridges of stalactites, that become purer and whiter as we retire from the light and the vege- tative influences, and present in the deeper recesses of the cave the hue of statuary marble. The last vegetable that appears is a minute delicate moss, about half an inch in length, which slants outwards to the light on the promi- nence of the sides, and overlies myriads of similar sprigs of moss, long since converted into stone, but which, faith- ful in death to the ruling law of their lives, still point, like the others, to the free air and sunshine. As we step on- A GEOLOGIST'S PORTFOLIO. 331 wards, we exchange the brightness of noon for the mel- lower light of evening. A few steps farther, and evening has deepened into twilight. We still advance : and twi- light gives place to a gloom dusky as that of midnight. We grope on, till the rock closes before us ; and, turning round, see the blue waves of the frith through the long, dark vista, as if we viewed them through the tube of some immense telescope. We strike a light. The roof and sides are crusted with white stalactites, that depend from the one like icicles from the eaves of a roof in a severe frost, and stand out from the other in pure, semi-transpar- ent ridges, that resemble the folds of a piece of white drapery dropped from the roof; while the floor below has its rough pavement of stalagmite, that stands up, wherever the drops descend, in rounded prominences, like the bases of columns. The marvel has become somewhat old-fash- ioned since the days when Buchanan described the drop- ping cave of Slains, " where the water, as it descends drop by drop, is converted into pyramids of stone," as one of the wonders of Scotland, and deemed it necessary to strengthen the credibility of his statement by adding, that he had been "informed by persons of undoubted veracity that there existed a similar cave among the Pyr- enees." Here, however, is a puzzle to exercise our ingenuity. Some of the minuter stalactites of the roof, after descend- ing perpendicularly, or at least nearly so, for a few inches, turn up again, and form a hook, to which one may sus- pend one's watch by the ring ; while there are others that form a loop, attached to the roof at both ends. Pray, how could the descending drop have returned upwards to form the hook, or what attractive power could have drawn two drops together, to compose the eliptical curve of the loop ? The problem is not quite a simple one. It is sufficiently 332 DESCRIPTIVE SKETCHES FROM hard at least, as it has to deal with only half-ounces of rock, to inculcate caution on the theorists who profess to deal with whole continents of similar material. Let us examine somewhat narrowly. Dark as the recess is, and though vegetation fails full fifty feet nearer the entrance than where we now stand, the place is not without its inhabitants. We see among the dewy damps of the roof the glistening threads of some minute spider, stretching in lines or depending in loops. And just look here. Along this loop there runs a single drop. Observe how it de- scends, with but a slight inclination, for about two inches or so, and then turns round for about three quarters of an inch more; observe further, that along this other loop there trickle two drops, one on each side ; that, as a conse- quence of the balance which they form the one against the other, their descent has a much greater sweep ; and that, uniting in the centre, they fall together. We have found a solution of our riddle, and received one proof more of the superiority of the simple art of seeing over the ingen- ious art of theorizing. But let us proceed to the proper business of the excur- sion. We have provided ourselves with tools for digging; and, selecting a spot some thirty feet within the cavern, where the bottom seems composed of a damp dark mould, we set ourselves, with spade and pick-axe, to penetrate to the sea-gravel beneath. The soil yields as easily to the tool as a piece of garden mould ; and, turning it up to the light in cubical adhesive masses, we find it consisting of an impalpable brown earth, that exactly resembles raw umber. We have fallen on a bed of pure guano, not quite so rich, perhaps, as that which our agriculturists export from the rocky islets of South America, at the rate of about fourteen pounds per ton, for it must have been A GEOLOGIST'S PORTFOLIO. 333 formed originally of vegetable, not animal matter, and we find that it lacks the strong ammonical smell of the guano produced by predacious water-birds ; but, judging from its appearance, and from the high estimate formed of old of the dung of pigeons as a manure, it must be of value enough to deserve removal from the damp unproductive floor of the Doo-cot. We find the bed which it com- poses extending downwards from two to three feet, and filling the cavern from side to side. A rock-gravel lies below, hardened into an imperfect breccia by a ferrugin- ous cement; but the rotting moisture exuded from the guano has been unfavorable, apparently, to the preserva- tion of the shells, and we find that it contains nothing organic. We again remove to the inner recesses of the cave. Mark first, that peculiar appearance along the sides. There stands out, at the height of about four feet from the present floor, what seems a rude projecting cornice of rock -gravel, bound together by the stalactitical cement : the projection at one point somewhat exceeds eighteen inches ; and we find it bearing short-stemmed' stalagmites atop, just like the rugged pavement below. To use a homely but apt illustration, the appearance is tha$ pre- sented by the lower part of a tallow-candle that had been burning, exposed to a current of air, with its grease run- ning down in ridges on the sides, and then spreading out on the margin of the metal socket, when, after raising it out of the candlestick, we see the lower accumulation pro- jecting from it like a cornice. That line of projecting gravel indicates the level at which the floor of the cavern once stood. If we remove the looser parts of the present floor, we shall find its place indicated by just a similar line of projection. The loose sea-gravel could have adhered to the sides only by having formed the part of the flopr in 334 DESCRIPTIVE SKETCHES FKOM contact with them, until the stalagmitical substance had taken effect upon it, by binding it into a mass, and fixing it where it had lain. Let us break into one of the projec- tions. We find it a true breccia, thickly interspersed with such fragments of shells as we may pick up by hundreds in the neighboring sea-caves, where the incessant beat of the surf on the hard rocks against which it dashes breaks them into rounded fragments. There, for instance, is a massy little bit of the strong smooth buckie, (Fusus An- tiquus), the largest of British univalves ; and there a frag- ment equally massy of the Icelandic Venus, both of them productions of the oceans, and of such rivers as the Friths of Cromarty and Dornoch. The materials of the projecting cornice are those of a cavern-beach much ex- posed to the roll of the surf. Let us now see what our several points of circumstan- tial evidence amount to. First, then, the bottom of the cave must have stood at one time at least four feet over its present level, and at least fourteen feet over the level of the two sea-caves outside ; and yet, just as the sea now covers them, must the sea at that remote period have covered it. The incessant wave must have resounded along these silent walls as it dashed sullenly onwards, and awakened all their echoes with its harsh rattle as it rolled back. The cavern at that early time, like all the other deep-sea caves of the coast, could have had no crust of stalactites. Its sides and roof must have been as dark and bare as the sides and roofs of the caves outside, where the spray washes away every film of calcareous matter ere it has been deposited for half a day. A sudden elevation of the coast took place, and sudden it must have been, for the loose gravel beach, with its finely comminuted shells, was at once raised beyond the influence of the tides ; the A GEOLOGIST'S PORTFOLIO. 335 stalactitical ridges began to form on the walls, and the sea-gravel to consolidate where these terminated be- neath, and the petrifying water oozed through into the brecciated cornice. But the waves from the lower line had been encroaching inwards, bit by bit, from the cavern's mouth, washing down the floor to their own reduced level, until they had at length scooped it all out, and left but the hardened projections to mark where it had stood. The cave, though now occupied by only the higher tides, had again become, in some sort, a sea-cave, when a second elevation of the land raised it to its present level. The covering of stalactites thickened along its sides ; its minute mosses lived, died, and became marble ; and, as age suc- ceeded age, the dark recesses in its roof were cheered by the unerring affections of instinct ; and brood after brood, reared with assiduous labor to maturity, went forth, some again to return to their hereditary cells, some to take up their abodes with man. I need scarce say, that the rock, or white-backed dove, is the original of our domestic species. LINE OF CROMARTY SUTOR. We find that there leaned against one of the precipices of the Southern Sutor, now washed by the spring tides, a talus of loose debris, such as we see still leaning against the precipices of the old coast line, and that a calcareous spring, dropping upon it from an upper ledge, had, in the course of years, converted its apex into a hard breccia and cemented it to the rock, while the base below remained incoherent as at first. During this period it must have lain beyond the sweep of the waves. But a change of level took place ; the waves came dashing against the loose debris, and swept it away ; and all that now remains 336 DESCRIPTIVE SKETCHES FROM of the talus is the consolidated apex, projecting about three feet from the rock. Under another precipice of the Cromarty Sutor we find a line of consolidated debris which, like the breccia of the apex, must have been the work of a calcareous spring running out about fifty feet into the ebb, where it is altogether impossible it could have formed now. The spring must have flowed down- wards for these fifty feet ere it reached the sea; for no sooner could it have touched the latter than its waters would have been diffused and lost ; and, even could they have avoided such diffusion, the waves must have pre- vented the loose gravel on which the calcareous matter acted from remaining sufficiently stationary for a single tide. In each of these cases is the value of the evidence enhanced by the circumstances in which it is given. Both the talus and the brecciated line were formed on a basis of gigantic rock, so hard that it strikes fire with steel, and which only a general change of level could have let down to the influence of the tide, or elevated over it. LESSON TO YOUNG GEOLOGISTS FROM CLAY-BED OF THE NORTHERN SUTOR. There is a stiff, blue clay much used in Cromarty and the neighborhood for rendering the bottom of ponds water- tight, and the foundations of cellars impervious to the land-springs, and which, save for its greater tenacity, much resembles the blue boulder-clay of our Coal Measures. It is found in the ebb at half-tide, in a bed varying from eighteen inches to three feet in thickness, which overlies the red boulder-clay, and contains minute fragments of shells, too much broken to be distinguished. I had deemed it a sort of re-formation from strata of a grayish-colored A GEOLOGIST'S PORTFOLIO. 337 aluminous shale, which occur in the Old Red Sandstone, and are laid bare in the neighborhood by the sea. The waves dash against them, and then roll back turbid with the lighter particles, to deposit these in the deep, still water outside. But in the place at present occupied by the bed the waves could not have deposited them ; it is so much exposed to the surf, that the deposit is gradually wearing down under the friction, and it must have been formed, therefore, at a lower level, and when the sea beat against the ancient beaches. We find further proof that such must have been the case in a soft stratum of gray, shaly sandstone, which rises through the bed, and which is thickly perforated by cells of the Pholas candiclus, con- taining in abundance the dead shells, but which has been elevated to a too high place to form any longer a fit habitat for the living animals. I had often examined the frag- mentary shells of this clayey layer, in the hope of being able to elicit from them somewhat regarding the history of a deposit older than our present coast line, yet newer than our boulder-clay ; but I had hitherto found them in every case too comminuted to yield the necessary evi- dence. I now succeeded, however, in detecting the same deposit under the Northern Sutor, in the same close neigh- borhood as on the Cromarty side to the gray aluminous shale of the Old Red Sandstone, to which it seems to have owed its origin, and abounding in organisms marine and terrestrial. All are recent. I found it containing cones of our common Scotch fir, hazel-nuts, fragments of aider and oak, shells of the common mussel much decomposed, and shells, too, of one of the Gaper family (Myce are- nan'rt), still lying in pairs. The blue, adhesive clay in which they *are embedded can scarce be distinguished from that of the Lower Lias of Eathie; the sets of organ- 29 338 DESCRIPTIVE SKETCHES FROM isms in the two deposits are also the same, indicating that their deposition must have taken place under similar conditions. The Lias, like the recent clay, has its cones, its bits of wood, and its marine bivalves lying in pairs ; and the sole difference that obtains between them is, that while the cones, and wood, and bivalves of the blue clay are all existences of the present time, the cones, and wood, and bivalves of the Lias represent classes of organic beings that have long since passed into extinction. This clay- bed of the Northern Sutor is one of the best places I know for the young geologist taking his first lesson upon. I deemed it of interest chiefly as corroborative of the fact that our raised beaches on the shores of the Cromarty and Moray Friths belong to exactly the. present state of things ; nay, that for a very inconsiderable period ere their elevation, when the blue bed was forming in com- paratively de'ep water, both sea and land were stored with their existing productions. GLACIAL APPEARANCES AT NIGG AND LOGIE. There are two several localities in which, after acquaint- ing one's-self with the glacial moraines of Brora, one may examine with advantage the glacial moraines of the neigh- borhood of Cromarty. One of these we find in the parish of Logic, not a hundred yards distant from the great coach road ; the other, in the parish of Nigg, on one of the slopes in which the lofty ridge, whose south-western termination forms the northern Sutor, sinks at its north- eastern boundary into the plain of Easter Ross. The Logie moraine extends, for full three-quarters of a mile, in a line parallel to the mountain range from which its glacier must have descended. There is a furzy level in A GEOLOGIST'S PORTFOLIO. 330 front, mottled over with groups of cottages ; the moraine, thickly planted with fir, and amid whose sheltering hollows the gipsies' tent may be seen in the warmer months, and the houseless Free Church congregation at this inclement season, forms a long undulating ridge, in what a painter would term the middle ground of the landscape ; while on the swelling acclivities behind, over which the icy plane must have once extended, we see woods, and fields, and stately manor-houses, and, high above all, the heathy mountain ridge, where the sky seems resting on the land. I have not seen the rock laid bare in any part of the cultivated tract which intervenes between the moraine and the upland ridge ; but I enter- tain little doubt that its surface will be found to bear the characteristic groovings and polishings of the glacial period. The moraines of the Hill of Nigg, as might be premised from the lower elevation and narrower slopes of the em- inence from which their glacier descended, are of small extent, compared with the moraine of Logie. There is, however, one of the number, a beautiful grassy Tomhan, fringed at the base with its thickets of dwarf-birch and hazel, that was deemed commanding enough in some early age, to be selected as the site of a hill-fort, still known to tradition as the Danish camp, and whose double mound of turf we may still see encircling the summit. It must have been a dreary period when the great glacier of Logie, sloping towards the south, and the lesser glacier of the hill of Nigg, sloping towards the north, saw them- selves reflected in the separating strait of sea which at this remote period flowed through the flat valley be- tween. The valley is still occupied for half its length by a sandy estuary, known as the Sands of Nigg, which, ere the upheaval of the higher beaches, must have existed as a 340 DESCRIPTIVE SKETCHES FROM shallow channel, through which the Frith of Cromarty then a double-mouthed arm of the sea, with the hill of Nigg as a mountainous island in the midst communi- cated with the Moray Frith beyond. PHENOMENA EXPLANATORY OF ACCUMULATIONS OF SHELLS. There are scarce any of the appearances with which the geologist is conversant more mysterious than the immense accumulations of shells which he occasionally finds, as in some parts of Sweden, separated from all extraneous mat- ter, as if they had been subjected to some sifting process, cleaned, as it were, and laid by ; and it has long been a question with him how this sifting process had been effected. The theory that the accumulation had been heaped up by great floods, through which substances of the same specific gravity were huddled together, has been the commonly accepted one; but who ever saw a flood, however great, that did not cast down its mud and its clay among its transported shells, or that had not mingled them, in the process of removal, with its lighter gravels or its sand? In the flat estuary of Nigg, I have seen the sifting process effected through a simple but adequate agency. For about two miles from where the estuary opens into the Cromarty Frith, its wide tracts of yielding sand are thickly occupied by the shells that love such lo- calities, in especial, by the common cockle. Almost every tide, when the animals are in season, furnishes its vast quantities for the markets of the neighboring towns, and still the supply keeps up ample as at first. Now the tracts of sand which they inhabit, if not properly quick- sands, are at least extremely loose, especially when cov- ered by the tide; and though the creatures succeed, so A GEOLOGIST'S PORTFOLIO. 341 long as they live, in maintaining their proper place in them within a few inches of the surface, no sooner do they die than the shells begin gradually to sink downwards through the unsolid mass, till, reaching, at the depth of about six feet, a firmer stratum, they there accumulate, and form a continuous bed. The work of accumulation has been going on for many centuries; generation after generation has been dying, to undergo this process of burial, this pro- cess of subarenaceous deposition, if I may so speak ; and there are places in the estuary in which the shelly stratum has risen to within a foot or two of the surface. It forms a sort of quarry of shells ; and when, about thirty years ago, there was a lime-work established in the neighbor- hood, many thousand cartloads were dug out and burnt into lime. I had frequent occasion, some five or six years since, to pass through the estuary at seasons when the mere amateur would have perhaps staid at home. There runs through it a stream of fresh water, that drains the flat fields and scattered lochans of Easter Ross ; and on one of my winter journeys, after a sudden thaw, accompanied by heavy rains, I found the stream swollen to the size of a considerable river, and its bed excavated beneath the usual level some three or four feet, with the sectional line of sand and shells through which it had cut standing up over it like a wall. There was first, reckoning downwards, from a foot to eighteen inches of pure sand ; and next, from two feet to two feet and a half of dead shells. The sandy tract all around, for many hundred acres in extent, used to be.partially covered with water; every ^furrow of the ripples, and every depression of the surface, borrowed its full from the receding tide, and', from the general flatness, retained it till its return. But on this occasion, the sur- face-water had found an unwonted drainage, through the 29* 342 DESCK1PTIVE SKETCHES FROM upright sectional front, into the newly excavated bed of the stream. It sank through the upper arenaceous layer as through a filtering stone, and then came rushing through the stratum of shells underneath, brown with the sand which it swept from their interstices. Nor could there be a completer sifting process. For yards and roods together the shells were as thoroughly divested of the sandy ma- trix in which they had lain as if they had been carefully washed in a sieve. I was bold enough to infer from the phenomenon at the time, that the problem of the unmixed accumulation of shells may be, in at least some cases, not so difficult of solution as has been hitherto supposed. One has but to take for granted conditions such as those of the estuary of Nigg, the incoherent bed, half a quicksand, and the subarenaceous deposition, to account for their original production, and the superadded conditions of the surface-water and the free drainage, to account for their after clearance of extraneous matter. CAUTION TO GEOLOGISTS ON TUB FINDING OF REMAINS. In consolidated slopes- it is not unusual to find remains, animal and vegetable, of no very remote antiquity. I have seen a human skull dug out of the reclining base of a clay bank, once a precipice, fully six feet from under the surface. It might have been deemed, not without a de- gree of plausibility, the skull of some long-lived contem- porary of Enoch, perchance that of one of the accursed race, " Who sinned and di land's Sermons. Delivered in the Chapel of Brown Univ. 12mo. Cl., 11.00. Entertaining and lust motive Works FOR THE YOUNO. Elegantly illustrated. IGmo. Cloth, gilt backs. The American Statesman. 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