Junction of Geologic and Human History — Scottish History of Modem Date — The Two Periods previous to the Roman Invasion: the Stone Age and the Bronze Age — Geological Deposits of these Prehistoric 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 — 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 Prevalence 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.
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 modem 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 the first human inhabitants rather on what may be deemed  geologic than on the ordinary historic data; and, on the other hand, some of the later 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 accession 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 Cathedral 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 document has descended, or no native inscription decipherable by the antiquary. A few votive tablets and altars, lettered 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 presents itself to our imagination an indefinite period, dateless as eternity, — a state rather than a time. For even the sense ot succession is lost in the uniformity of the stream.' 
It is, however, more than probable that the age of Agricola 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 Cæsar 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 represent always the stage of civilisation 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 civilisation, there seems 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 employed 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 comparatively 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 superseded by the bronze.1 Now, it is truly wonderful how thoroughly, for all general purposes, this scheme of classification, which we owe to the Danish antiquary Thomsen arranges into corresponding sections and groups the antiquities 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,
1 In an interesting article on Ireland which lately appeared in the Scotsman newspaper, I find it stated that for a very considerable distance, 'between Lough Rea and Lough Derg, the river Shannon was fordable at only one point, which of course formed the only medium of communication 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.'
 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 civilisation. 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 narrative as the confused transactions and battles of the Saxon Heptarchy.' But the subject arises at once in dignity 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 archæologically  and in its remains. And I would appeal, in justification of the preference, to the great superiority in interest and value of the recently published Prehistoric Annals of Scotland, by our accomplished townsman Mr. Daniel Wilson, over all the diffusive 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 deposits or formations of the two prehistoric 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 superficial 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 prevalence 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 existence of our species upon the earth, and make man contemporary 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 existing 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 civilisation are bare and treeless. 'When, in passing from our thickly foliated forests of oak, we cross,' he says, 'the Alps or the Pyrenees, and enter Italy or Spain, or when the traveller first directs his eye to some of the African coasts of the Mediterranean, 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 forgets, too, that an earlier civilisation of the human race sets bounds to the increase of forests; and that nations, in their change-loving spirit , gradually destroy the decorations which rejoice our eye in the north, and which, more than the records of history, attest the youthfulness of our civilisation.' Some of my audience must be old enough to remember the last of the great aboriginal woods of Scotland. It was only during the second war of the first French Revolution, when the northern ports of Europe were shut against Great Britain, that the native pine-woods of Rothiemurchus and the upper reaches of the Spey were cut down; and as late as the year 1820, I looked, in the upper recesses of Strathcarron, on the last scattered remains of one of the most celebrated of the old pine-forests of Ross-shire. Possibly some of the fragments of the pine-forest 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 instances, 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 débris of a prostrated forest the woodman frequently 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 Possil 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 similar 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 similar utensil was found; a Roman jug was found in Lochar Moss, Dumfriesshire; a pot and decanter of Roman copper was found in a moss in Kirk- michael parish, in the same county; and two pair of 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 circumstances, 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 torn 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-coloured 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 accumulation 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 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 remains, but apparently of a still more ancient type, have been laid open in Aberdeenshire; and I find Mr. Wilson stating, in his archæological history, that on several occasions, 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, Dumfriesshire, with ornamental torcs and brass bowls, not less evidently of the subsequent 'bronze period.' It is stated by Dr. Boate, 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 Donegal), with the remains of an ancient plough, and the wattles 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 storeys, 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 Bos Primigenius or native ox, and of the Cervus 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 animals named the Irish elk and native ox were contemporary with the primitive hunters of the stone period the cervical vertebrae of a native ox have been found deeply scarred by a stone javelin, and the rib of an Irish elk perforated by a stone arrow-head; and it is known that some of the extirpated animals, such as the wild horse, wolf; and beaver, continued to live among our forests down till a comparatively 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 statement. It is unquestionable, however, that the Gaelic name of the creature, Lasleathin, or broad-tail, still survives; and equally certain that when Baldwin, Archbishop 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, Cardiganshire. The wolf and wild horse maintained their place in at least the northern part of the island for several centuries 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
1 Many interesting human remains have lately been disinterred from the Severn drift 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.
 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.
The sand dunes of the country, — accumulations of sand heaped over
the soil by the winds, and in some cases, as in the neighbourhood 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 arro-heads of
with splintered masses of the material out of which they had been
— the débris, apparently, of the workshop of some weapon-maker
the stone period. Among a tract of sand dunes on the shores of the
Firth, immediately under the Northern Sutor, in a hillock of blown
which was laid open about eighty years ago by the winds of a stormy
there was found a pile of the bones of various animals of the chase,
the horns of deer, mixed with the shells of molluscs of the edible
and, judging from the remains of an ancient hill-fort in the neighbour
and from the circumstance that under an adjacent dune rude sepulchral
were disinterred many years after, I have concluded that the hunters by
they had been accumulated could not have flourished later than at least
age of bronze. It was ascertained in one of the Orkneys, about the year
that a range of similar dunes, partially cleared by a long tract of
winds from the west, had overlain for untold ages what seemed to be the
of an ancient Scandinavian village. In fine, very  strange fossils
the human period has this sand deposit of subaerial formation been
to contain. There were disinterred on the Cornish coast in 1835, out of
immense wreath of sand, an old British church and oratory, — the church
oratory of Perran-sabulæ, — which had been hidden from the eye of
for nearly a thousand years. The Tractarian controversy had just begun
the time to agitate the Episcopacy of England; it had become of
to ascertain the exact form of building sanctioned by antiquity as most
to devotion; and a fossil church, which had undergone no change almost
the times of the ancient Christianity, was too interesting a relic to
the notice of the parties which the controversy divided. But though
volumes were written regarding it, in a style not quite like that in
Professor Owen and Dr. Mantell have since discussed the restoration of
Belemnite, it was ultimately found that the little old church of St.
the Culdee, — such a building as Robinson Crusoe might have erected for
ecclesiastical uses of himself and his man Friday, — threw exceedingly
light on the vexed question of church architecture. The altar is in the
said the Tractarians. Nay, the building itself does not lie east and
replied their opponents. We grant you it does not, rejoined the
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 labourer who saw
just ere it fell says there was a large hole in it. And thus the
ran on, undoubtedly amusing, and, I daresay, very instructive. The
of Scotland has its ancient fossil barony underlying a wilderness of
ploughed fields and fences, with the walls of turf-cottages, and the
of a manor-house, all irrecoverably submerged ; — and we find the fact
in a  Scots Act of the times of William III. Curious, as being
the only Act of Parliament in existence to which the geologist could
for the history of a deposit, I must take the liberty of submitting to
a small portion of one of its long sentences. 'Our Sovereign Lord,'
the preamble, 'considering that many lands, meadows, and pasturages,
on the sea-coasts, have been ruined and over spread in many parts of
kingdom by sand driven from sand-hills, the which has been mainly
by the pulling up of the roots of bent, juniper, and broom bushes,
did loose and break the surface and scroof of the sand-hills; and
considering that the barony of Cawbin, and house and yeards thereof;
within the sheriffdom of Elgin, is quite ruined and overspread with
the which was occasioned by the foresaid bad practice of pulling the
and juniper, — does hereby strictly prohibit,' etc. etc. etc. I have
for hours amid the sand-wastes of this ruined barony, and seen only a
stunted bushes of broom, and a few scattered tufts of withered bent,
amid utter barrenness, the place of what, in the middle of the
century, had been the richest fields of the rich province of Moray;
where the winds had hollowed out the sand, I have detected, uncovered
a few yards'-breadth, portions of the buried furrows, sorely dried into
consistence of sun-burned brick, but largely charged with the seeds of
common corn-field weeds of the country, that, as ascertained by
by the late Sir Thomas Dick Lauder, still retain their vitality. It is
that an antique dove-cot in front of the huge sand wreath which
the manor-house, continued to present the top of its peaked roof over
sand, as a foundered vessel sometimes exhibits its vane over the waves,
the year 1760. The traditions of the district testify that, for many
after the orchard had been enveloped, the top most branches of the
barely seen over the surface,  continued each spring languidly to
out bud and blossom; and it is a curious circumstance, that in the
churchyard of Dike there is a sepulchral monument of the Culbin family,
though it does not date beyond the reign of James VI., was erected by a
and lady of the last barony, at a time when they seem to have had no
of the utter ruin which was coming on their house. The quaint
runs as follows
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 formations 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 memorials of nations that have perished, and of a condition of things and a stage of society that have for ever passed away.VALER KINNAIRD : ELIZABETH INNES : 1613:
THE : BVILDARS : OF : THIS : BED: OF STANE:
AR : LAIRD : AND : LADlE : OF : COVBINE:
QVHILK : TVA : AND : THARS : QVHANE : BRAITHE IS : GANE:
PLEIS : GOD : VIL : SLEIP : THIS : BED : VITHIN:
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 by the historian — for its date is anterior to that of his oldest  authorities in this country, — the land rose, apparently 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 Scotland 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 between 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. That 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 algæ; the one consisting, under its covering of vegetable mould, of stratified gravels and sand, blent with the decayed shells of mollusca that died more than twenty centuries since, — the other formed of exactly the same sort of lines of stratified sand and gravel,  and strewed over by shells that were thrown ashore by the last tide, and that lived only a few weeks ago. And, rising over the lower, as over the upper flat, we see a continuous escarpment, which marks where, in the present age, during the height of stream tides, the sea and the land meet; just as the upper 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 somewhat softer in their outline than the lower, — an effect of the wear of the elements, and of the accumulation of the vegetable mould. There is as thorough an identity between them as between two contiguous steps of a stair, covered, the one by a patch of brown, and the other by a patch of green, in the pattern of the stair-carpet. There are other parts of our Scottish shores in which the old coast line is of a much bolder character than anywhere in this neighbourhood, 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 Barry, is at least 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 Firth, immediately below and for several miles to the east of the town of Tam, where it attains a breadth of from one to two miles, and where the old sea-margin, rising over the cottage-mottled plain below in a series of jutting headlands, with green bosky bays between, 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 neighbourhood of Cromarty, and on the opposite shores of the Cromarty Firth, 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 neighbourhood of Dornoch, a long withdrawing firth, 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 porpoise. Along the upper recesses of almost all our flatter firths, such as the firths of Beauly, of Dingwall, 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 neighbourhood 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, Kirkcaldy, Dundee, Dingwall, Invergordon, Cromarty, Wick, Thurso, Kirkwall, Oban, and Greenock, have been built upon it.
The old coast line, with the flat marginal selvage at its base,
I have said, well-marked features in the scenery of the island. Geology
be properly regarded as the science of landscape: it is to the
what anatomy is to the historic one or to the sculptor. In the
rich and variously compounded prospects of our country there is scarce
single trait that cannot be resolved into some geological peculiarity
the country's framework, or which does not bear witness otherwise and
directly than from any mere suggestion of the associative faculty, to
striking event in its physical history. Its landscapes are tablets
like the tablets of Nineveh, with the records of the past; and their
features, whether of hill or valley, terrace or escarpment, form the
and graceful characters in which the narra tive is inscribed. As our
geologists have given less attention to this special department of
science than to perhaps any other, — less, I am disposed to think,
from its intrinsic interest and its bearing on art, is
 fairly owing to it — I shall take the liberty — casting 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 surfaces, 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 grey upright stone of other days waves its beard of long grey lichen to the breeze, — are not unworthy, in their impressive loneliness, 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 colour, 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 surface, to the wave-like form of the hills sloped in the direction of the prevailing winds, and curved, like snow wreaths, to the opposite point of the compass, almost every outline is equally suggestive of motion. I could, however, fain borrow the pencil of our countryman Hill, as he employs 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 suffocating dust snatched up by a whirlwind; the antique garden dial dimly shadowing forth the hour of sunset for the last time amid half-submerged shrubs and trees; and, full in  the centre of the picture, a forlorn fortalice of the olden time, with the encroaching wreath rising to its lower battle ments, like some wrecked vessel on a wild lee-shore, with the angry surf raging high over her deck, and kissing with its flame-like tips the distant yards.
The scenery of the old coast line possesses well-nigh all the variety of that of the existing coast; but it substitutes field and meadow for the blue sea, and woods and human dwellings for busy mast-crowded harbours, and fleets riding at anchor. It is pleasing, however, to see headland jutting out beyond headland into some rich plain, traversed by trim hedgerows 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 specimens of this scenery of the ancient coast line in our immediate neighbourhood. 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, and gay with villas, and which may possibly have been its first Celtic designation, Inveresk, ere the last upheaval of the land, half-closes around it. The church and burying-ground occupy the top of a long ridge, that had once been a river-bar, heaped up apparently by the action of the waves on the one side, and by that of the stream on the other. But, as shown by the remains of Roman baths and a Roman rampart, which once occupied its summit, it must have borne its present character from at least the times of Lollius Urbicus, — perhaps for several centuries earlier. The neighbouring town of Portobello, as seen from the east, just as it comes full in sight on the Musselburgh road, seems set so completely in a framework of the ancient escarpment, that it derives from it all its natural features. But it is where, along our  bolder shores, lines of steep precipices have been elevated over the sea, so that the waves no longer reach their bases, that the old coast scenery is at once most striking and peculiar. Tall picturesque stacks, which had once stood up amid the surf; brown and shaggy with the serrated fucus and the broad-fronded laminaria, now rise out of thickets of fern or sloethorn, and wave green with glassy ivy and the pendant honeysuckle. Deep caverns, too, in which the billows had toiled for ages, but now silent, save when the drop tinkles from above into some cool cistern half-hidden in the gloom of the interior, open along the wall of cliffs; and over projecting buttresses of rock, perforated often at their bases as if by Gothic archways, and thickly mantled over by liver-worts, green and grey, the birch hangs tremulous from above, or the hazel shoots out its boughs of brighter green, or the mountain-ash hangs its scarlet berries. One of the most pleasing landscapes of one of the most accomplished of female artists, — Miss Stoddart, — has as its subject an ancient 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 foliage, hollowed into deep recesses, adown which the waters trickle, 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  ground one of those long, flat, sandy spits, products of the last upheaval, which, stretching far into the sea, bear amid the light of day an air of even deeper loneliness than our woods and fields when embrowned by the gathering night. When the insulated stacks of an old coast line are at once tall and attenuated, and of a white or pale-coloured rock, the effect, especially when viewed by moonlight, is singularly striking. The valley of the Seine, as described by Sir Charles Lyell, — now a valley, but once a broad firth, — 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 imperfect 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 Scotland this flat fringe of margin-land, with its picturesque escarpment 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-archæologic character, by one of our highest authorities on the subject, Mr. Smith of Jordanhill, that the land must have stood at a not lower level than now, when the Roman wall which connects the firths of Forth and Clyde was completed. For, had it been other wise, 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 Cæsar, — a fact recorded by Diodorus Siculus, — is similarly connected with the main land 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 inhabitant 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 Balænoptera,' says Professor Owen, 'seventy-two feet in length, was found,' about thirty years ago, 'imbedded in the clay on the banks of the Forth, more than twenty feet above the reach of the highest tide.' And again, 'Several bones of a whale,'1 he continues, 'were also discovered at Dunmore 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 waves, and the marginal strip existed as an oozy sea-bottom; 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 an other in the Andersonian Museum, — have been dug up since the year 178I; 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
1 Bones of the whale have been found in the clay of the Avon and Severn drifts, in a similar position. — W. S. S.
 Firth 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 Antiquarian 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 civilisation, or in the Indian Archipelago, among the rude Alforian races; and that in another of these boats, — the first discovered, — there was found a beautifully polished hatchet of dark green stone, — an unequivocal indication that they belonged to the 'stone period.' There are curious etymologies 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 neighbourhood of Stirling, 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 eminences may be perhaps regarded as suggestive enough to account for their names. One of these etymologies, however, 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 mediæval. And, curiously 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 immemorial 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 historic ages, it is comprised within the human period. But we can not, as has been shown, fix upon a date for the event.
Were the case otherwise, — could we fix with any certainty the time when this change of level took place, and the platform of the lower coast line was gained from the sea, — there might be an approximation made to the anterior space of time during which the line of high water had been the willow-crowned escarpment beyond Portobello and the green bank near Rutherglen, and the sea rose far beyond its present limits in our firths and bays. There are portions of the coast that at this early period presented to the waves lines of precipices that are now fringed at their bases by strips of verdure, and removed far beyond their reach. There are other portions of coast in the immediate neighbourhood of these, where similar lines of precipices, identical in their powers of resistance, were brought by the same movement within that very influence of the waves beyond which the others had been raised. And each line bears, in the caves with which it is fretted, — caves hollowed by the attrition of the surf in the direction of faults, or where masses of yielding texture had been included in the solid rock, — indices to mark, proportionally at least, the respective periods during which they were exposed to the excavating agent. Thus, the average depth of the ancient caves in an exposed line of coast, as ascertained by dividing the aggregate sum of their depths by their number, and the average depth, ascertained by the same process, of the recent caves, equally exposed on the same coast, and hollowed in the same variety of rock, could scarce fail to represent their respective periods of exposure, had we but a given number of years, historically determined, to set off against the average measurement of the recent excavations.  Even wanting that, however, it is something to know, that though the sea has stood at the existing sea-margin since the days of Agricola, and at least a few centuries more, it stood for a considerably longer period at the old coast line. The rock of which those remarkable promontories, the Sutors of Cromarty, are composed, is a granitic gneiss, much traversed by faults, and enclosing occasional masses of a soft chloritic schist, that yields to the waves, while the surrounding 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 existing 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 hundred feet; the deepest of the ancient ones, now so completely raised above the surf; that in the highest tides, and urged upwards by the severest storms, the waves never reach its mouth, measures exactly a hundred and fifty feet. And these depths, though much beyond the respective average depths of their several rows, bear, so far as I could ascertain the point, the proportions to each other that these averages bear. The caves of the existing coast line are as two in depth, and those of the old coast line as three. If the excavation of the recent caves be the work of two thousand years, the excavation of the ancient caves must have been the work of three thousand; or, as two thousand 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 ancient either coast line may be, we of course cannot determine:  we only know that, on the lowest possible assumption, we reach a period represented by their united ages only less extended by six years than that which the Samaritan 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 eight-six years to the sum of the latter.
Permit me, in closing this part of my subject, to show you that changes of level such as that to which we owe our old coast line in Scotland, and the marginal strip of dry land which we have laid out into so many pleasant gardens and fields, and on which we have built so many of our seaport towns, are by no means very rare events to the geologist. He enumerates at least five localities in the Old World, — Scandinavia, part of the west coast of Italy, the coasts of Cutch and of Arracan, and part of the kingdom of Luzan, in which the level is slowly changing at the present time; and in the New World there are vast districts in which the land suddenly changed its level for a higher one during the present century. 'On the 19th of November 1822,' says Sir Charles Lyell, 'the coast of Chili was visited by a most disastrous earthquake. When the district around Valparaiso was examined on the morning 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 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 hundred 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 oflicers of Her Majesty's brig Childers; 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 uncultivated; 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 paroxysm of elevation; and, with the upheaval of the coast of Chili, and a numerous class of events of a similar character, it enables us to conceive of the last great geological change of which our country was the subject. We imagine a forest-covered land, marked by the bold commanding features by which we recognise our country, but inhabited 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, — 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 uncovered vast tracts never seen before, comparatively barren in sea-weed, but rich in stony nulliporite incrustations, minute corallines, and fleshy sponges. Ages elapse, and civilisation 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 wrested 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 neighbourhood, 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 Scotland dates, it would seem, beyond the human period. In passing along the beach between Musselburgh and Portobello, or again between Portobello and Leith, or yet again between Leith and Newhaven, one sees an exceedingly stiff, dark-coloured 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 Boulder-Clay. Though not continuous, it is of very general occurrence, in the Lowlands of Scotland, and presents, though it varies in colour and composition, according to the nature of the rocks which it overlies, certain unique appearances, 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 contributed 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 invariably 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 pyramidal peaks between; and, thus combining the perpendicularity 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 land scape. 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 escarpments, which in some parts form the old coast line, and rise in others along the sides of rivers, that we detect at once the most marked and most graceful scenic peculiarity of the boulder-clay. The steep slopes, furrowed by enormous 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 neighbourhood of Cromarty, these mounds are striking 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 buttresses of the poet, a singularly pleasing feature in the landscape. I have sometimes wished I could fix their features in a calotype, for the special benefit of my friends the landscape 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 disintegrating 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 appearances, which connect its origin in the several localities 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 in stances, 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 contains 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 materials 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 decidedly of an oblong or spindle shape, the scratchings occur, in at least four cases out of every five, in the line of their longer axis. Now, the agent which produced such effects could not have been simply water, whether impelled 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 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 are not launched forwards, as a sailor would say, end on, but tumbled 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 forward 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 produced such effects as the longitudinal scratching, let us ask what could have produced them? There are various processes 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 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-pave ments 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 fishing began to be prosecuted with vigour 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 operations 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 ponderously over them; and they with a speed diminished in ratio from that of the moving power in proportion to the 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 converted 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 sandstone, 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 sand stone pavement, and converts the solid stone into impalp able mud. Further, the colour of the mud or clay would correspond, as in the thoroughfare or public road, with the colour 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 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 neighbourhood, with worn and rounded fragments of broken shells; and we see it almost invariably borrowing its colour 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 labourer engaged in rubbing it smooth with water and a polisher of gritty sandstone. This clay varies in quality and colour with the character of the stone operated upon. A flag of Arbroath pavement yields a bluish-coloured clay; a flag of the Old Red of Ross or Forfarshire, a reddish coloured clay; a flag of Sutherlandshire 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 colouring 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 colour and quality, just such a clay as might be produced by this recipe of the mason's labourer from the rocks on which it rests. The red sandstone rocks  of Moray, Cromarty, and Ross are covered by red boulder-clays; a similar red boulder-clay overlies the red sandstone rocks of Forfarshire; and I was first apprised, when travelling in Banffshire some years ago, that I had entered on the district of the Old Red, by finding the boulder-clay assuming the familiar brick-red hue. Over the pale Oolites of Suther landshire, as at Brora and Golspie, it is of a pale yellow tint, and of a yellowish red over the pale Old Red Sand stones of the long flat valley known as the Howe of Fife. Again, in the middle and north-western districts of Caithness, where the paving flagstones so well known in commerce give to the prevailing rocks of the district a sombre tint of grey, the boulder-clay assumes, as in the neighbourhood of Wick and Thurso, the leaden colour 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 colour which might be premised, on the polishing theory, 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 condition of resemblance in average colour 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 oc casionally find the trail of the rubbings of one tract over lying, in an easterly direction, the deposits of a different one; just as we would find the rubbings of variously-coloured pieces of pavement laid down to form a floor, and then polished square by square where they lay, encroaching, the débris 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, enclosed in it, accompanied, in  not a few instances, by rounded fragments of shells, and a general conformity in its colour to that of the rocks on which it rests, — where in nature shall we find the analogues of the producing rafts themselves? A native of Newfoundland, who season after 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 illustration, and some powerful ocean current, such as the gulf or arctic stream, for the river itself, and we at once ar rive 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 degrees 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 northern shores are included in that vast cake of ice which, when winter sets fairly in, is found to stretch continuously, 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 southwards 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 isothermal 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 latitude 47°; and old York, in the fifty-fourth degree of north atitude, enjoys as much average warmth throughout the rear 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 permanent 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 centrical, — 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 fhe boulder-clay, resting over the scratched and grooved rocks, and accompanying the scratched and polished pebbles, is essentially a boreal or semi-arctic group. This little shell from the boulder-clay of Caithness, — the Trophon scalariformis or Fusus scalariformis, which, from its small size, seems to have escaped the fate that crushed its larger contemporaries into fragments, is not now found living on our coasts, though it still exists in considerable abundance in the seas of Greenland; and several of its neighbours in the clay, such as Tellina proxima and Astarte Borealis, are of the same northern character. Nay, in cases in which the shells of the boulder-clay still live in our seas, we find those of a northern character, such as the Cyprina Islandica, that, though not rare on the shores of Scotland, is vastly more abundant on those of Iceland, occurring, not in the present British, but in the present Icelandic proportions. The Cyprina Islandica is one of the most common shells of the clay, and, as its name testifies, one of the most common shells of Iceland; 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, — unquestionably 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 phenomenon. 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 divergent; 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 neighbourhood, whether he had ever seen much ice on the spot where we stood, the heat was so excessive (for we were in the latitude of the south of France, 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 uninterrupted 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 Blomidon, were often fifteen feet thick, and were pushed along, when the tide rose, over the sandstone 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 hardness 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 mechanical 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 harbours, 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 Wyvis, or northern group.
Let me next advert to a peculiarity in the direction of the icebergs which went careering at this period over the submerged land. As shown by the lines and furrows which they have graven upon the rocks, their general course, with a few occasional divergences, — effects, apparently, 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 attached to their eastern sides sloping ta/i 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 it kept from being swept away; and the simple effect, 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 castle's outer moat to Holyrood, existing as the tail; may be cited as a familiar instance. We find the same phenomenon repeated in the Calton Hill, and in various other eminences in the neighbourhood; as also in the Castle Hill of Stirling. And in all these, and 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 xvest. The testimony of the ice-grooved rocks, and of the eminences composed of crag and tail; bear, we see, in the same line.
Now, this westerly direction of the current seems to be exactly that which, reasoning from the permanent phenomena 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 accumulated during the winter, must have again melted in spring and early summer; and a current must in consequence have set in as the seasons of these came on, just as we now see such a current setting in in these seasons in both hemispheres, which bears the ice of the antarctic circle far towards the north, and the ice of the arctic circle far towards 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 Newfoundland; and by some the very existence of the bank has been attributed to their junction, and to the vast accumulation 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 boulders and the quantity of pebbles and gravel strewed over the bottom of the western portions of the Atlantic, in the line of the arctic current, from the confines of Baffin's Bay up to the forty-fifth degree of north latitude, must be altogether enormous. Captain Scoresby counted no fewer 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 disposition of the arctic and western continents, — perhaps also of the present position of the magnetic pole. A different arrangement and position would give a different  point of meeting; and it is as little improbable that they should have met in the remote past some two or three hundred miles to the west of what is now Scotland, as that in the existing period they should meet some two or three hundred miles to the east of what is now Newfoundland. The northern current would be deflected by the more powerful gulf stream into an easterly course, and would go sweeping over the submerged land in the direction indicated 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, leaving the clay which they had thus formed to be deposited over, and a little to the east of, the rocks that had produced it. It is further in accordance with this theory, that 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 grey milky dressings detached by the friction of the steel from the solid mass, to the end of the stone furthest from himself and there they accumu late thick in the direction of the stroke. And so it is here. The rubbings of the great Scotch whetstone, acted upon by the innumerable gravers and chisels whetted upon it, and held down or steadied by the icebergs, have been carried in the easterly 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; instead 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
you that this dreary ice-epoch in the history of our country still
as debatable a terra incognita to the geologist as the dreary
which surround the pole do to the geographer. We have been threading
twilight way through a difficult North-West Passage; and if our
has been in some degree one of weariness and fatigue, we must remember
without weariness and fatigue no voyager ever yet explored
'We might expect,' says Professor Sedgwick, 'that as we come close upon living nature, the characters of our old 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 Professor 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 wanting, — 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.'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.'