X^ .- LIBRARY UNIVERSITY OF I SCIENCE CALIFORNIA 7 LIBRARY 1 : I KEIEV LIBRARY DIVERSITY OF CALIFORNIA EARTH SCIENCES LIBRARY GOULD AND LINCOLN, 59 WASHINGTON STREET, BOSTON, Would, call particular attention to the following valuable worKS described in their Catalogue of Publications, viz. : Hugh Miller's Works. TJayne'S Works. Walker's Works. Miall's Works. Bungener's Work. Annual of Scientific Discovery. Knight's Knowledge is Power. Krummacher's Suffering Saviour, Banvard's American Histories. The Aimwell Stories. -rewcOmb's Works. Tweedie's Works. Chambers's Works. Harris' Works. K-itto's Cyclopaedia of Biblical Literature. *?rs. Knight's Life of Montgomery. Kitto's History of Palestin Wheewell's Work. Wayland's Works. Agassiz's Works. "William's Works. G-uyot's Works. Thompson's Better Land. Kimball's Heaven. Valuable Works on Missions. Haven's Mental Philosophy. Buchanan's Modern Atheism. Cruden's Condensed Concordance. Eadie's Analytical Concordance. The Psalmist : a Collection of Hymns. Valuable School Books. Works for Sabbath Schools. Memoir of Amos Lawrence. Poetical Works of Milton, Cowper, Scott. Elegant Miniature Volr.irT-. Arvine's Cyclopaedia of Anecdotes. Itipley's Notes on Gospels, Acts, and Romans. Sprague's European Celebrities. Marsh's Camel and the Hallig. Roget's Thesaurus of English Words. Hackett's Notes on Acts. M'Whorter's Yahveh Christ. f ibold and Stannius's Comparative Anatomy. Marco's Geological Map ; U. a. Religious and Miscellaneous Works. Works i the various Department? *>f Literature, Science and Art. SKETCH: BOOK OF POPULAR GEOLOGY. P'OPULAR GEOLOGY: SERIES OF LECTURES READ BEFORE THE PHILOSOPHICAL INSTITUTION OF EDINBURGH. kidjcs from a Mtogist's $)0rtf01i0. B Y HUGH MILLER. WITH AN INTRODUCTORY RESUME OP THE PROGRESS OF GEOLOGICAL SCIENCE WITHIN THE LAST TWO YEARS, B Y MRS. MILLER. BOSTON: OOULD AND LINCOLN, 59 'WASHINGTON STREET. NEW YORK: SHELDON AND COMPANY, CINCINNATI : GEORGE S. BLANCHARD. 1859, EARTH SCIENCES LIBRARY Entered according to Act of Congress, in the year 1859, by GOULD AND LINCOLN, In the Clerk's Off.ce of the District Court of the District of Massachusetts. ELECTUOTYPED BY W. F. DRAPER, AKbOVER, MASS. PIUNTED BY OEO. C. RAM> & AVEUY, BOSTON. PREFACE TO THE AMERICAN EDITION. THIS new volume, from the pen of HUGH MILLER, is a legacy wholly unlooked 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 Avriters of our century. It gives precisely what 1 463204 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 will 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 IlEV. . S. SlMONDS, 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 is 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 time 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 scrutinizing 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 you 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 sunny 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 quafled 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 his abundant grace, to enable you to per- form it aright. Ever believe me, dear Sir, Tours most faithfully, LYDIA MILLER. * The Malvern Club devotes stated periods, monthly, I think, to rambles over twenty or thirty miles of country, when the naturalists of whom it is composed, botanists, geologists, etc., carry on the researches of their various departments separately, or in little groups of two or three, as they may desire. They all dine afterwards together at an inn, or farm-house, as the case may be, where they relate the adventures of the day, discuss their favorite topics, and com- pare their newly-found treasures. As a consequence of this, the Malvern Museum is a perfect model of what a local museum ought to be. There is no town or district of country where a few young men, possessing the advantage of an occasional holiday, might not thus associate themselves with the utmost advantage both to themselves 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," the effect of it Probable Cause of the Westerly Direction of the Current, 37-83 1* VI CONTENTS. LECTURE SECOND. Problem first propounded to the Author in a Quarry The Quarry's Two De- posits, Old Red Sandstone and Boulder-Clay The Boulder-Clay formed while the Laud was subsiding The Groovings and Polishiugs of the Rocks 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 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 Deposits 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 Evi- dences of Glacial Action in Glencoe, Garelock, and the Highlands of Suther- landScenery of Scotland owes its Characteristics to Glacial Action The Period 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 the 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 Poet Delta (Dr. Moir) His Definition of Poetry His Death His Burial- place at Inveresk Vision, Geological and Historical, of the surrounding Country What it is that imparts to Nature its Poetry The Tertiary Forma- tion in Scotland In Geologic History all Ages contemporary Amber the Resin of the Pinus Succiniftr 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 th use 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-Pits 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, 168-202 -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- tencesThe 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-prints in theTriassic System The Triassic and Permian Systems once regarded as one, under the name of the New Bed 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 Coccosteus 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 owes its present Form The Author's views on the subject, 249-298 CONTENTS OF DESCRIPTIVE SKETCHES. Page ACCUMULATIONS OP SHELLS, PHENOMENA EXPLANATORY OF . . 340 AMMONITES OF THE NORTHERN LIAS ..... 348 ASTREA OF THE OOLITE, SUTHERLAND ..... 309 BELEMNITES OF THE NORTHERN LIAS ..... 349 BONE-BED, RECENT, IN THE FORMING ..... 302 BRAAMBURY, QUARRY OF, UPPER OOLITE, SUTHERLAND . . 316 BREWSTER, SIR DAVID, ON THE CUTTLE-FISH AND BELEMNITE . . 372 BRORA COAL FIELD OTHER THAN THE TRUE COAL-MEASURES . 311 BRORA PEAT-MOSSES OF THE OOLITE ...... 315 CAUTION TO GEOLOGISTS ON THE FINDING OF REMAINS . . 342 CLAY-BED OF THE NORTHERN SUTOR, LESSON TO YOUNG GEOLOGISTS , 336 CONGENERS OF THE CUTTLE-FISH, BELEMNITE, ETC. ... 357 COPROLITES OF THE LIAS ....... 365 CROMARTY ......... 328 CRO MARTY, CAVES OF, OR THE ART OF SEEING OVER THE ART OF THEO- RIZING ......... 329 CROMA.RTY SUTOR, LINE OF ....... 335 CUTTLE-FISH ......... 349 DIPTERUS MACROLEPIDOTU8, ABUNDANT IN THE BANNISKIRK OLD RED OF CAITHNESS ........ 304 EATHIE, INTRUSIVE DIKES OF . . . . . . .366 ECONOMIC GEOLOGY, LONDON MUSEUM OF .... 313 FOSSIL-WOOD OF THE OOLITE AT HELMSDALE, SUTHERLAND . . 306 X CONTENTS. GANOID SCALES AND RATS ....... GLACIAL APPEARANCES AT NIGG AND LOGIB .... GLACIERS AND MORAINES OF SUTHERLAND .... GRANITIC GNEISS AND SANDSTOWE, WITH THE CONDITIONS OF THEIR UPHEAVAL . . . . . . LEVEL STEPPES OP RUSSIA, AND THEORY OP MORAINES . SEPTARIA, OR CEMENT-STONES, OF THE LIAS .... TEREBRATULA, CONTEMPORARY AND EXTINCT TYPES OF THE LIFE OF TRAVELLED BOULDERS NOT ASSOCIATED WITH CLAY . TYPES, RECENT, OF FOSSILS ....... UNDERLYINGX'I-AY ON LEVEL MOORS, REMARKS ON . THEORY OF THE OCEAN'S LEVEL ...... CHAIN OF CAUSES . . . . . . . . RECENT GEOLOGICAL DISCOVERIES ...... SIR RODERICK MURCHISON ON THE RECENT GEOLOGICAL DISCOVERIES 4 EN MORAY8H1RE . INTRODUCTORY RESUME OF THE PROGRESS OF GEOLOGICAL SCIENCE, THE following Lectures, with " The Cruise of the Betsey," and " Rambles of a Geologist," are all that remain of what Hugh Miller once designed to be his Maximum Opus, THE GEOLOGY OF SCOTLAND. It is well, however, that his ma- terials have been so left that they can be presented to the public in a shape perfectly readable ; furnishing two volumes, each of which, it is hoped, will be found to possess in itself a uniform and intrinsic interest differing in matter and man- ner as much as they do in the form in which they have found an embodiment. That form is simply the one naturally arising out of the circumstances of the Author's life as they occurred, instead of the more artificial plan designed by himself, in which these circumstances would probably, more or less, if not alto- gether, have disappeared. Yet it may well be doubted whether .*. . : : :': : : .'. **' * .-* : : * .-.. 12 ' 'INTRODUCTORY RESUME: the natural method does not possess a charm which any more formal arrangement would have wanted. Every one must be struck with the freshness, buoyancy, and vigor displayed in the "Summer Rambles;" qualities more apparent in these than even in his more labored Autobiography, of which they are, indeed, but a sort of unintentional continuation. They were the spontaneous utterances of a mind set free from an occu- pation never very congenial, that of writing compulsory articles for a newspaper, to find refreshment amid the fami- liar haunts in which it delighted, and to seize, with a grasp easy, yet powerful, on the recreation of a favorite science, as the artist seizes on the pencil from which he has been sepa- rated for a time, or the musician on some instrument much loved and long lost, which he well knows will, as it yields to him its old music, restore vigor and harmonv to his entire being. My dear husband did, indeed, bring to his science all that fondness, while he found in it much of that kind of enjoyment, which we are wont to associate exclusively with the love of art. The delivery of these Lectures may not yet have passed quite away from the recollection of the Edinburgh public. They excited unusual interest, and awakened unusual atten- tion, in a city where interest in scientific matters, and attend- ance upon lectures of a very superior order, are affairs of every-day occurrence. Rarely have I seen an audience so PROGRESS OF GEOLOGICAL SCIENCE. 13 / profoundly absorbed. And at the conclusion of the whole, when the lecturer's success had been triumphantly established (for it must be remembered that lecturing was to him an experiment made late in life), I ventured to urge the propriety of having the series published before the general interest had begun to subside. His reply was, " I cannot afford it. I have given so many of my best facts and broadest ideas, so much, indeed, of what would be required to lighten the drier details in my ' Geology of Scotland,' that it would never do to pub- lish these Lectures by themselves." It will thus be seen that they veritably gather into one luminous centre the best por- tions of his contemplated work, garnering very much of what was most vivid in painting and original in conception, of that which has now, alas ! glided, with himself, into those silent shades where dwell the souls of the departed, with the halo of past thought hovering dimly round them, waiting for that new impulse from the Divine Spirit which is to quicken them into an intenser and higher unity. I have been led to indulge the hope that this work will be found useful in giving to elementary Geology a greater attrac- tiveness in the eyes of the student than it has hitherto pos- sessed. It was characteristic of the mind of its author, that he valued words, and even facts, as only subservient to the high powers of reason and imagination. It is to be regretted that many introductory works, especially those for the use of 2 14 INTRODUCTORY RESUME : schools, should be so crammed with scientific terms, and facts hard packed, and not always well chosen, that they are fitted to remind us of the dragon's teeth sown by Jason, which sprung up into armed men, being much more likely to repel, than to allure into the temple of science. One might, indeed, as well attempt to gain an acquaintance with English literature solely from the study of Johnson's Dictionary, as to acquire an insight into the nature of Geology from puzzling over such books. But, viewed in the light of a mind which had ap- proached the subject by quite another pathway, all unconscious, in its outset, of the gatherings and recordings of others, and which never made a single step of progression in which it was not guided by the light of its own genius and the inspiration of nature, it may be regarded by beginners in another aspect, one very different from that in which Wordsworth looked upon it when he thanked Heaven that the covert nooks of nature reported not of the geologist's hands, " the man who classed his splinter by some barbarous name, and hurried on." At that time the poet must have seen but the cold, hard profile of the man, instead of the broad, beaming, full-orbed glance which he may have cast over the wondrous aeons of the past eternity. To meet any difficulties arising from misconception, it may be proper to glance rapidly at what has been accomplished in geological research within the last two years. The reader will PROGRESS OF GEOLOGICAL SCIENCE. 15 thus avoid the painful impression that there are any suppressed facts of recent date which clash with the theories of the suc- ceeding Lectures, destroying their value and impairing their unity. And it may be well to remind him that there are two schools of Geology, quite at one in their willingness to bring all theories to the test of actual discovery, but widely differing in their leanings as to the mode in which, a priori, they would wish the facts brought to light to be viewed. The one, as expounded in the following Lectures, delights in the unfolding of a great plan, having its original in the Divine Mind, which has gradually fitted the earth to be the habitation of intelligent beings, and has introduced upon the stage of time organism after organism, rising in dignity, until all have found their completion in the human nature, which, in its turn, is a prophecy of the spiritual and Divine. This may be said to be the true development hypothesis, in opposition to the false and puerile one, which has been discarded by all geologists worthy of the name, of whatsoever side. The other school holds the opinion though, perhaps, not very decidedly that all things have been from the beginning as they are now ; and that if evidence at the present moment leans to the side of a gradual progress and a serial development, it is because so much remains undiscovered ; the hiatus, wherever it occurs, being always in our own knowledge, and not in the actual state of things. The next score of years will probably bring the matter to a pretty fair decision ; for it seems impossible that, 16 INTRODUCTORY RESUME: if so many able workers continue to be employed as industri- ously as now in the same field, the remains of man and the higher mammals will not be found to be of all periods, if at all periods they existed. In the meantime, it is well to know the actual point to which discovery has conducted us ; and this I have taken every pains most carefully to ascertain. The Upper Ludlow rocks the uppermost of the Silurians continue to be the lowest point at which fish are found. Up to that period, during the vast ages of the Cambrian, where only the faintest traces of animal life have been de- tected 1 in the shape of annelides or sand-boring worms, throughout the whole range of the Silurians, where shell-fish and crustaceans, with inferior forms of life abounded, no traces of fish, the lowest vertebrate existences until the latest formed beds of the Upper Silurian, have yet appeared. There are now six genera of fish ranked as Upper Silurian, Auchenaspis, Cephalaspis, Pteraspis, Plectrodus, Onchus Mur- chisoni, and Sphagodus. The two latter Onchus Murchisoni and Sphagodus are represented by bony defences, such as are possessed by placoid fishes of the present day. Sir Rod- erick Murchison at one time entertained the idea of placing the Ludlow bone-bed at the base of the Old Red Sandstone ; but its fish having been found decidedly associated with Silu- rian organisms, this idea has been abandoned. i See the lately published edition of Sir Roderick Murchison's " Siluria," chap. ii. p. 20. PROGRESS OF GEOLOGICAL SCIENCE. 17 The next point to which public attention has been specially directed, is the discovery of mammals lower than they had formerly appeared. Considerable misconception has arisen on this head. The Middle Purbeck beds, recently explored by Mr. Beckles, in which various small mammals were found, occur considerably farther up than the Stonesfield slates, in which the first quadruped was detected so far back as 1818. But this discovery involves no theoretical change, inasmuch as all the mammalian remains of the Middle Purbecks consist of small marsupials and insectivora, varying in size from a rat to a hedgehog, with one or two doubtful species, not yet proved to be otherwise. The living analogue of one very interesting genus is the kangaroo rat, which inhabits the prairies and scrub-jungles of Australia, feeding on plants and scratched-up roots. Between the English Stonesfield or Great Oolite, in which, many years ago, four species of these small mammals were known to exist, and the Middle Purbeck, quarried by Mr. Beckles, in which fourteen species are now found, there intervene the Oxford Clay, Coral Rag, Kimmeridge Clay, Portland Oolite, and Lower Purbeck Oolite ; and then, after the Middle Purbeck, there occurs a great hiatus throughout the Weald, Green Sand, Gault, and Chalk, wherein no quad- rupedal remains have been found ; until at length we are introduced, in the Tertiary, to the dawn of the grand mamma- lian period; so that nothing has occurred in this department to occasion any revolution in the ideas of those who, with my 2* 18 INTRODUCTORY RESUME: husband, 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 Microlestes 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 Carolina (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, wldle 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 Microlestes 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 Palasozic 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 mystery 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 time." 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,^vith 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 their 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 diaries 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 1 See Terebratula, page 111. The extinct Terebratula is now called Rhynconella. 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 Maestricht, 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 Yoluta, 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 Tertiaries. 3 26 INTRODUCTORY RESUME: considerable change in the GEOLOGY OF SCOTLAND. The next edition of the "Old Red 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 overlying quartzose, micaceous, and other crystalline rocks, some 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 those on the east, and therefore ' Old Red Sandstone.' . . . Professor Nicol had suggested that the quartzites and lime- stones might be the equivalent of the Carboniferous system of the south of Scotland. Wholly dissenting from that hypoth- PROGRESS OF GEOLOGICAL SCIENCE. 27 * esis, lie (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- shire 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 Duff, 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 Morayshire Courier, makes too much of the recent discoveries in his neighborhood, when he asserts that the Old Red Sandstone had been hitherto consid- ered exclusively a fish formation, and that the appearance of reptiles is altogether novel. " Now," says he, " that the Old Red 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 no higher order of beings than fishes." 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- tained in his day, reptiles are made to occupy precisely the position they do now. To refresh 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. .uaa. Art. moi. Fishes. Reptiles. Permian. Triassic. Oolitic. Birds. Mammals. Cretaceous. : : Tertiary. ria. Mam, Geologic [Bad. Art. Mol. Fish. Rep. Bird. Mam. Man.] arrangement. Cuvier's [Rad. 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 Telerpeton JElginense, with the doubt 3* 30 INTRODUCTORY RESUME: us to the nature of its locale very sHghtly touched upon. 1 All this Mr. Duff has forgotten, apparently ; and it appears like- wise not to have come within his cognizance that Sir Charles Lyell distinctly recognizes his Telerpeton, as well as the American foot-prints, and assigns both their proper places, in the last edition of his " Principles." Even in the edition before the last of the " Siluria," almost the first thing that meets us, on opening it at Chapter Tenth, which treats of the Old Red Sandstone, is a print of the fossil skeleton of this same Teler- peton Elginense its true place assigned to it with quite as much certainty as now ! These very singular lapses in mem- ory seem not to be peculiar to Mr. Duff. I have seen it stated, in an anonymous article published in a widely-circu- lated journal, 2 and in connection with the discovery of the Elgin reptile foot-prints, that Hugh Miller considered the Old Red Sandstone 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 This doubt, I see by Sir Roderick Murchison's latest Address to the British Association, is not yet entirely obviated. See page 422. 2 For this article, as an excellent specimen of its class, see page 409, under the head "Recent Geological Discoveries;" and, in contradistinction to it, the extract from Sir R. Murchison's Address ought to be -carefully studied. I myself had seen neither that extract, nor the recent " Siluria," until after this short sketch was in type, the references to the latter hav- ing been introduced afterwards, and it may be conceived with what feel- ings of gratification I have perused Sir Roderick's repeated assurances of adherence to the " Old Light." 3 See Contra, p. 246. 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 from 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 have 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 believe, 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." 84 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 peircive clearly the alterations which have taken place in our Scottish 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 itself, 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, I 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 and the Bronze Age Geological Deposits of these Pre-historic Periods The Aboriginal 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 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 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 prevalence in the Lowlands of Scotland Indicated in the Scenery of the Country The Scratchiugs on the Boulders accounted for Produced by the grating of Icebergs when Scotland was submerged Direction in which Ice- bergs floated, from West to East " Crag and Tail " the Eflect of it Probable Cause of the Westerly Direction of the Current. IN 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 portions 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 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 taken 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. Tytler'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, when 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 is at 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. 89 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 the " 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 Ca3sar 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 40 LECTURES ON GEOLOGY. never to have been a tribe or nation that had not at one time recourse to this most obvious of substances for their tools and weapons. Then comes an age in which stone is supplanted by the metals that occur in a native state, i. e. in a state of ductility in the rock, such as copper, silver, and gold. Of these, copper is by much the most abundant ; and in all countries in which it has been em- ployed for tools and weapons, means have been found by the primitive workers to harden it through an admixture of other metals, such as zinc and tin. Last of all, the com- paratively occult art of smelting iron is discovered, and the 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 other ; and the battle-axe and chisel of hardened copper (bronze) are as certainly superseded by it as the chisel and the 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- fication, which we owe to the Danish antiquary Thomsen, arranges 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- tance, " between Lough Rea and Lough Derg, the river Shannon Avas ford- able at only one point, which of course formed the only medium of com- munication between the natives of the two banks. They seem, however," it is added, "to have met oftener for war than peace; and from this ford a whole series of ancient warlike weapons was dug out. These weapons are now preserved in the fine collection of antiquities in the Museum of the Royal Irish Academy in Dublin, and are partly bronze and partly stone. Their position in the river bed told a curious tale, both historically and geologically. The weapons of bronze were all found in the upper stratum, and below them those of stone; showing, as antiquaries well know, that an age of bronze followed not an age of gold, but an age of stone." 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 lived 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 archa3ologically 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- gravels, 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- ence 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" Some 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 Rothieraurchus 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 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 Roman camp-kettle was found eight feet deep under a moss on the estate of Ochtertyre; in Flanders Moss a LECTURES ON GEOLOGY. 45 similar utensil was found; a Roman jug was found in Loclier 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 46 LECTURES ON GEOLOGY. remains, apparently, of such primitive huts as those in which, according to Gibbon, the ancient Germans resided, and 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 archaBological 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 ancient plough, and the wat- tles of a hedge six feet beneath the surface. In 1833 there was 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 cases of the extinct animals, such as gigantic skulls and horns of the J3os Primigenius or native ox, and of the Cer- vus Megaceros or Irish elk, with the skeletons of wolves, of beavers, of wild horses, and of bears. There exists what seems 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 havejbeen 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 1526; but there rests a shadow of doubt on the state- ment. It is unquestionable, however, that the Gaelic name of the creature, Lasleatliin, 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 lately been disinterred from the Severn d,rift and gravels near Tewkesbury, 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 heaped 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 Perran-sabula), which 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. Pirran 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- 5 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-coasts, have been ruined and overspread in many parts of this 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 sheriifdom of Elgin, is quite ruined and overspread with sand, the which was oc- casioned 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 each 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 utter ruin which was coming on their house. The quaint inscription runs as follows : VALER : KINNAIRD : ELIZABETH : INTQ8 : 1613 : THE : BVILDARS : OF : THI8 : BED t OF : STAKE : AR : LAIRD : AND : LADIE : OF : COVBINE : QVHILK : TVA : AND : THAR8 : QVHANE : BRAITHE IS : GANE : PLEIS : GOD : VI L : SLEIP : 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, manor-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 time, one may pass from the ancient to the recent sea- beach ; the one waving with grass, the other brown with LECTURES ON GEOLOGY. 53 algaa ; 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 jsea 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 eflfect 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 scries 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 of 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 Leith, Portobello, Musselburgh, Kirkaldy, Dundee, Dingwall, Invergordon, Cromarty, Wick, Thurso, Kirk wall, 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 jis the science of landscape : it is to the landscape painter what anatomy is to the historic one or to the sculptor. In 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- try's framework, or which does not bear witness otherwise LECTURES ON 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, arc 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 CO LECTURES OX GEOLOGY. surface to the ware-like form of the hiUs 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, amid hall-submerged shrubs and trees ; and, fufl in the centre of the picture, a forlorn fbrtalice 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 Inaaang 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 tins 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, now laid out into fields, gardens, and a race-course ; and the old coast escarpment, luxuriant with hanging woods, LECTURES W GEOLOGY. 57 and gay with villas, and which mar possibly hare been its first Celtic designation, Hweresk, ere the last upheaval of the land, half closes around it. The church and borying- 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 most have borne its present character from at least the times of Lollios Urbicus, perhaps for several centuries earlier. The neighboring port of Portobello, as seen from the east, just as it conies full in sight on the Mnsselburgh 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 focus 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 far 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 dins ; 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 tain-ash hangs Hs scarlet berries One of the landscapes of one of the most accomplished of artists Miss Stoddart has as its 58 LECTUEES 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 spHs, 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 efiect, 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 CaBsar, 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 Balae- noptera," says Professor Owen, "sevenity-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 i Bones of the whale have been found in the clay of the Avon and Severn drifts, in a similar position. W. S. S. 60 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 Bothwell 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 ON GEOLOGY. tainty the time when this change of level took place, ai the platform of the lower coast line was gained from t sea, there might be an approximation made to the ant rior space of time during which the line of high water h; been the willow-crowned escarpment beyond Portobel and the green bank near Rutherglen, and the sea rose i beyond its present limits in our friths and bays. The are portions of the coast that at this early period present to the waves lines of precipices that are now fringed their bases by strips of verdure, and removed far beyoi their reach. There are other portions of coast in t immediate neighborhood of these, where similar lines < precipices, identical in their powers of resistance, we brought by the same movement within that very influen of the waves beyond which the others had been raise And each line bears, in the caves with which it is frette caves hollowed by the attrition of the surf in the dire tion of faults, or where masses of yielding texture h; been included in the solid rock, indices to mark, prop( tionally at least, the respective periods during which th were exposed to the excavating agent. Thus, the av( age depth of the ancient caves in an exposed line of coa as ascertained by dividing the aggregate sum of th< depths by their number, and the average depth, ascertain- by the same process, of the recent caves, equally expos- on the same coast, and hollowed in the same variety rock, could scarce fail to represent their respective perio of exposure, had we but a given number of years, histc ically determined, to set off against the average measui nient of the recent excavations. Even wanting that, ho 1 ever, it is something to know, that though the sea h stood at the existing sea-margin since the days of Agri ola, and at least a few centuries more, it stood for a co LECTURES ON GEOLOGY. fc 63 siderably longer period at the old coast line. The rock of i which those remarkable promontories, the Sutors of Cromarty, are composed, is a granite gneiss, much trav- ersed by faults, and inclosing occasional masses of a soft chloritic 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- O ' ing coast, 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 tico in depth, and those of the old coast line as three. If the excavation of the recent caves be the work of tico 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 winch 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 examined 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 dry 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 OX 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 : he 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- land 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 IsTewhaven, 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. G7 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 sexton frets the surface of a country churchyard, but with this 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- tures in a calotype, 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 scratching^ occur, in at least four cases out of every five, in the line of their longer axis. !N"ow, 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 are, the further are the stones propelled. They arc 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 were not rolled, but slidden for- ward in the line of their longer axis. They were launched, 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 Highland fields, for instance, I have seen the rock beneath, or the stones buried at the depth of but a few inches from LECTURES 0$ 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, more 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 many 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 thoroughfare 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. Now, in the boulder-clay we 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 smooth 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 BnnfFshire 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 : LECTURES ON GEOLOGY. stones of the long, flat valley known as the Howe of Fife. 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 assumes, 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 rafts them- selves? A native of Newfoundland, who season after LECTURES ON GEOLOGY. 75 -x 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 temperature 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 forty-first degree. Now, the causes which give to countries in the same latitudes climates so strangely different are known not to be per- 76 LECTURES OST 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 Troplion 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 proximo, 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 France, 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 1841] 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 ice-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 ad veil 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 away ; 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. nomcna 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 sec 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 B;iy up to the forty-fifth degree of north latitude, must be alto- gether enormous. Captain Scoresby counted no fewer I LECTURES ON GEOLOGY, 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 so 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 giA^e 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 wear 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 ON GEOLOGY. 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 a 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 OX GEOLOGY. 83 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 awanting, 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 Groovings and Polishings of the Rocks in the Lower Tarts 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 MS 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 paleon- 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 out 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 8 80 LECTURES ON GEOLOGY. the 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 imdergoing 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 Otf GEOLOGY. 87 perhaps higher than it does now ; that ages of depression came 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 arid 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- logical Society," May, 1858, 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 off 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 lie states, in the note to which I have referred, that he has 8* 90 LECTURES OX GEOLOGY. 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 Excelsa, 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 musk buf- falo, are the leading types of the mammalian fauna of the Glacial Drift epoch. The remains of hippopotami* would be washed out of older beds. \V. S. 92 LECTURES OX 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 Magog, the wooden giants of Guildhall : our Scottish legends of the same class are less famous ; but to one of their number charged i 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 Kilmnurs parish; and they may now be seen in the Himterian 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 lies bene fourtene feet of hicht, with squaire membres effering 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 oure 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 ; Awhile 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 horse mussel (Modi- ola vulgaris), and the common whelk (Buccinum unda- tum). 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. \V. S. 94 LECTURES ON GEOLOGY. at a still later period ; the common mussel (Mytilus edu- lis), the common periwinkle (Littorina littoreci), and, in Britain at least, the dog-whelk (Purpura lapittus), 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 fays 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 lied 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 came 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 new 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 96 LECTURES ON GEOLOGY. rashly 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 owo 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 remains 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 Egypt, in which dynasties are represented as having flour- ished thousands of years ere the era of Abraham. The chronicles of all nations have their fabulous introductory portions. 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 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 earth, 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 GEOLOGY. recent events of which it submits the memorials to its votaries. But to return : The glacial or ice period in Scotland seems to have extended from the times of the stratified beds, charged with sub-arctic shells, which underlie the boulder-clay, until the land, its long period of depression over, was again rising, and had attained to an elevation less by only fifty or a hundred feet than that which it at present maintains. Such is the height over the sea-level, of the raised beach at Gamrie in Banffshire ; and in it the arctic shells last appear. And to the greatly-extended sub-arctic period in Scotland there belong a class of ap- pearances which have been adduced in support of a glacial as opposed to an iceberg theory. But there is in reality no antagonism in the case. After examining not a few of our Highland glens, especially those on the north-western coast of the country, I have arrived at the conviction, that Scotland had at one time its glaciers, which, like those of Iceland, descended along its valleys, from its inland heights, to the sea. And as in most cases certain well- marked accompaniments of the true glacier, such as those lateral and transverse moraines of detached rock and gravel that accumulate along their sides and at their lower terminations, are wanting in Scotland, it is inferred -that great currents must have swept over the country since the period of their existence, and either washed their moraines away, or so altered their character and appearance that they can be no longer recognized as moraines. Of course, this sweeping process might have taken place during that period of profound subsidence when the boulder-clay was formed, and in a posterior period of more partial subsidence, which is held to have taken place at a later time and un- der milder climatal conditions, and which is said to have LECTURES ON GEOLOGY. 99 brought down the land to its present level from a considera- bly higher one. In many localities there rests over the true boulder-clay an argillaceous or gravelly deposit, in which the masses and fragments of rock are usually angular, and which, even where the boulder-clay is shell-bearing, con- tains no shells. There are other localities in which a sim- 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 for 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, where 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 glaciers 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 ichence the glacier descended, and more angular and ab- rupt in the direction towards ichich 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 OX 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 o 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. 10 o 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,