The Continuity of Existences twice broken in Geological History — The three great Geological Divisions representative of three independent Orders of Existences — Origin of the Wealden in England — Its great Depth and high Antiquity — The question whether the Weald Formation belongs to the Cretaceous or the Oolitic System determined in favour 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 Outliers 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.
 

THE mystic thread, with its three strands of black, white, and grey, spun by the sybil in Guy Mannering, formed, she said, a 'full hank, but not a haul ane:' the lengthened tale of years which it symbolized 'was thrice broken and thrice to asp.' I have sometimes thought of that wonderfully mingled and variously coloured thread of existence which descends from the earliest periods known to the geologist down to our own times, as not unaptly represented by that produced on this occasion from the spindle of the gipsy. We find, in its general tissue, species interlaced with and laying hold of species, as, in the thread, fibre is interlaced with and lays hold of fibre; and as by this arrangement the fibres, though not themselves continuous, but of very limited length, form a continuous cord, so species of limited duration, that at certain parts in the course of time began to be, and at certain other parts became extinct, form throughout [122] immensely extended periods a continuous cord of existence. New species had come into being ere the old ones dropped away and disappeared; and there occurred for long ages no break or hiatus in the course, just as in the human family there occurs no abrupt break or hiatus, from the circumstance that new generations come upon the stage ere the old ones make their final exit. But in the geological thread, as in that of the sybil, the continuity is twice abruptly broken, and the thread itself divided, in consequence, into three parts. It is continuous from the present time up to the commencement of the Tertiary period; and then so abrupt a break occurs, that, with the exception of the microscopic diatomaceæ, to which I last evening referred, and of one shell and one coral, not a single species crosses the gap. On its further or remoter side, however, where the Secondary division closes, the intermingling of species again begins, and runs on till the commencement of this great Secondary division; and then, just where the Palæozoic division closes, we find another abrupt break, crossed, if crossed at all, — for there still exists some doubt on the subject, — by but two species of plant.¹ And then, from the further side of this second gap the thread of being continues unbroken, until we find it terminating with the first beginnings of life upon our planet. Why these strange gaps should occur, — why the long descending cord of organic existence should be thus mysteriously broken in three, — we know not yet, and never may; but, like the division into books and chapters of some great work on natural history, such as that of Cuvier or Buffon, it serves to break up the whole according to an intelligible plan, the scheme of which we may, in part at least, aspire to comprehend. The three great divisions of the geologist, — Tertiary, Secondary, and Palæozoic, — of which these two chasms, with the beginnings

¹ For a reference to the research of the last two years, which has been busily at work upon this precise epoch, see Preface.

[123] of life on the one hand, and the present state of things on the other, form the terminal limits, — represent each, if I may so express myself an independent dynasty or empire. Under certain qualifications, to which I shall afterwards refer, the Tertiary division represents the dynasty of the mammal; the Secondary division the dynasty of the reptile; and the Palæozoic division the dynasty of the fish. Each of the divisions, too, has a special type or characteristic fashion of its own; so that the aspect of its existences differs as much in the group from the aspect of the existences of each of the others, as if they had been groups belonging to different planets. The vegetable and animal organisms of the planet Venus may not differ more from those of the planet Mars, or those of Mars from the organisms of the planet Jupiter, than the existences of the Tertiary division differ from those of the Secondary one, or those of the Secondaiy one from the existences of the Palæozoic division.

Beneath the two great divisions of the Cretaceous system, and consequently of more ancient date, there occurs in the sister kingdom an important series of beds, chiefly of lacustrine or fluviatile origin, known as the Wealden. Before the submergence of what are now the south-eastern parts of England, first beneath the comparatively shallow sea of the Greensand, and then beneath the profounder depths of the ocean of the Chalk, a mighty river, the drainage of some unknown continent, seems to have flowed for many ages along those parts of Kent, Surrey, and Sussex, known as the Valley of the Weald. The banks of this old name less river were covered with forests of coniferous trees of the Pine and Araucarian families, with cycadeæ and ferns, and were haunted by gigantic reptiles, herbivorous and carnivorous, some of which rivalled in bulk the mammoth and the elephant; its waters were inhabited by amphibiæ of the same great class, chiefly crocodiles and chelonians of extinct species and type; by numerous fishes, too, of the old [124] ganoid order; and by shells whose families, and even genera, still exist in our pools and rivers, though the species be all gone. Winged reptiles, too, occasionally flitted amid its woods, or sped over its broad bosom; and insects of the same family as that to which our dragon-flies belong spent the first two stages of their existence at the bottom of its pools and shallows, and the terminal one in darting over it on their wings of delicate gauze in quest of their prey. It is stated by Dr. Mantell, our highest authority on the subject of the Weald, that the delta of this great river is about two thousand feet in thickness, — a thickness which quadruples that of the delta of the Mississippi. There can be little doubt that the American 'Father of Waters' is a very ancient river; and yet it would seem that this river of the Wealden, which has now existed for myriads of ages in but its fossilized remains, hidden under the Wolds of Surrey and Kent, — this old river, which flowed over where the ocean of the Oolite once had been, and in turn gave place and was overflowed by the ocean of the Chalk, — continued to roll its downward waters amid forests as dense and as thickly inhabited as those of the great American valley, during a period perhaps four times as extended.

Compared with the English formation of the Weald, which extends over a wide, and what was at one time a very rude district, our beds of the Scotch Wealden are but of little depth, and limited extent. And yet they serve to throw a not unimportant light on the true character and place of the formation. It occurs in England, as I have said, between two great marine systems, — the Cretaceous and the Oolitic; and the question has arisen, to which of these systems does it belong? Now, our Scotch beds of the Weald determine the question. They make their appearance, not at the top of the Oolitic deposits, as in England, but intercalated throughout the system, — occurring in the Isle of Skye, where they were first detected many [125] years ago by Sir Roderick Murchison, immediately under the Oxford clay, a bed of the Middle Oolite; and at Brora, where they were first detected a few twelvemonths since by Mr. Robertson of Elgin, in pretty nearly the same medial position, and where what is known as the great Oolite occurs. Three years ago I had the pleasure of detecting a bed of the same lacustrine or estuary character, and bearing many of the characteristic marks of the Weald, greatly lower still, — lower, indeed, than any fresh-water deposit of the Secondary division in Britain. I found it occurring not forty yards over the bottom of the Lias, — the formation which constitutes the base of the Oolitic system. In Moray-shire the Weald occurs in the form of outliers, that rise, as at Linksfield, in the immediate neighbourhood of Elgin, into low swelling hills, resting on the Old Red Sandstone of the district, and so thoroughly insulated from every other rock of the same age, that they have reminded me of detached hillocks of débris and ashes shot down on the surface of some ancient moor by some painstaking farmer, who had contemplated bringing the waste under subjection to the plough. But though valueless, from their detached character, for determining the place of the formation, they serve better than the intercalated beds of Ross, Skye, and Sutherland, to establish by their animal remains the pake ontological identity of the Scotch with the English Wealden.

Rather more than twelve years ago, the late Dr. John Malcolmson of Madras, — a zealous and accomplished geologist, too early lost to science and his friends, — brought with him, when on a visit to the Continent, several specimens of ichthyic remains from a Morayshire deposit, and submitted them to Agassiz. 'Permit me,' said the naturalist, 'to find out for myself the formation to which they belong.' He passed hand and eye over tooth and spine, plate and bone, and at length set his finger on a single scale of rhomboidal form.and brightly enamelled surface. 'Some of these teeth,' [126] he said, 'belong to the genus Hybodus, but the species are new, and the genus itself has a wide range. Here, however, is something more determinate. This scale belongs to the Lepidotus minor, or ichthyolite of the Weald, and one of the most characteristic fishes of the great fresh-water formation of Surrey and Kent.' The fossils on which the distinguished ichthyologist thus promptly, and, as it proved, correctly decided, had been collected by Dr. Malcolrnson fiom the the Wealden outlier at Linksfield; and the ichthyolite which he so specially singled out, — the Lepidotus, — seems to have been a fresh-water fish of the nearly extinct ganoid order, and more nearly akin to the Lepidosteus of the North American rivers and lakes than to any other fish that now exists. By much the greater number of its contemporaries in the deposit also belonged to lakes and rivers. Some of the limestone slabs are thickly covered over by fresh-water shells, of types very much akin to those which still occur in our pools and ditches, such as Planorbis and Paludina. It presents also beds of a fresh-water mussel akin to a mussel of the English Weald, — Mytilus Lyellii; and it so abounds in the remains of those minute, one-eyed crustaceans known as the Cyprides, that the vast numbers of their egg-shaped shelly cases give to some of the beds a structure resembling the roe of a fish. It contains, too, bones of a species of tortoise, and several other decidedly fresh-water remains while another class of its organisms serve to show that it was occasionally visited by denizens of the sea. It has furnished specimens of bones and teeth of Plesiosaurus, — a marine reptile; and some of the upper beds contain a small oyster; while a class of its remains, — the teeth and huge dorsal spines of Hybodonts, an extinct family of sharks, though they may have been fitted to sustain life in brackish water, seem to indicate rather a sea than a lacustrine or river habitat. The deposit took place in all probability in the upper reaches of an estuary operated upon by the tides, and [127] at one time fresh and at another brackish, and where, in a certain debatable tract, the fishes, reptiles, and shells of the river met and mingled with the fishes, reptiles, and shells of the sea. I may mention, that in the immediate neighbourhood of the fresh-water or Weald beds, intercalated, as in Ross and Sutherland, with the marine deposits of the Lias or Oolite, there always occur beds of a species of shell, which, though it exhibits internally a peculiar structure of hinge, unlike any other known to the conchologist, bears externally very much the appearance of a mytilus or mussel. It seems to have lived in brackish water, and to have marked a transition stage between the marine and lacustrine, — the salt and the fresh; for immediately under or over it, as the case occurs, the explorer is ever sure to find productions of the land or of fresh water, — lake or river shells, such as cyclas or paludina, or portions of terrestrial plants, and occasionally of fresh-water tortoises. This transition shell is known as the Perna. These notices you will, I am afraid, deem tediously minute; but they indulge us with at least a glimpse of a portion of what is now our country during an immensely extended period, of which no other record exists. Where some nameless river enters the sea, we determine, as through a thick fog, which conceals the line of banks on either hand, that the waters swarm with life, reptilian and ichthyic: the glossy scales of the river Lepidotus gleam bright through the depths ; while the shark-like Hybodus from the distant ocean shows above the surface his long dorsal fin, armed with its thorny spine; and over beds of shells of mingled character, a carnivorous fresh-water tortoise, akin to the fierce Trionyx of the southern parts of North America, meets with the scarce more formidable sea-born Plesiosaurus.

In these Morayshire Outliers of the Weald we first find in situ in our country (for we need scarce take into account the Tertiary beds of Mull), fossiliferous deposits that have been [128] converted into solid rock; and certainly the appearance of some of the sections is such as to awaken curiosity. In the section of Linksfield, in the neighbourhood of Elgin, though the thickness of the deposit does not exceed forty feet, there occur numerous alternations of argillaceous and calcareous beds, differing from each other in colour and quality, and not unfrequently in their fossils also; and each of which evidently represents a state of things which obtained during the period of their deposition, distinct from the preceding and succeeding states.¹ Strata of grey, green, blue, and almost black clays, alternate with beds of light green, light brown, grey, and almost black limestones; and such is the effect, when a first section is opened in the deposit, as some times happens to facilitate the working of a limestone quarry below, that one is reminded, by the variety and peculiar tone of the colours, of the inlaid work of an old-fashioned cabinet made of the tinted woods which were in such common use about two centuries ago. Some of these bands seem, from their contents, to be of fresh water; some of marine origin; one bed nearly four feet in thickness is composed almost exclusively of the shelly coverings of a minute crustacean, — Cypris globosa, — not half the size of a small pin head; one is strewed over with the teeth of sharks; one with the plates and scales of ganoidal fishes; in one a small mussel is exceedingly abundant; another contains the shells of Planorbis and Paludina; in this layer we find a small

¹ Fielding, in his Voyage to Lisbon (1754), gives an account of an in accessible bank of mud which stretched at low water between the shore at Ryde and the sea. 'Between the shore and the sea,' he says, 'there is at low water an impassable gulf of deep mud, which can neither be traversed by walking nor swimming, so that for near one-half of the twenty-four hours Ryde is inaccessible by friend or foe.' The same tract now is occupied by an expanse of firm white sand, which forms excellent bathing ground; but immediately under, at the depth of from eighteen inches to two feet, the mud of Fielding's days is found occurring as a dark-coloured impalpable silt.

[129] oyster, which must have lived in the sea; in that, a Cyclas, the inhabitant of a lake; here the plates of a river tortoise; there the bones of the marine Plesiosaur. Of all the many- coloured strata of which the deposit consists, there is not one which does not speak of that law of change of which the poet, as if in anticipation of the discoveries of modern science, sings so philosophically and well: —

'Of chance or change, oh! let not man complain,
Else shall he never, never cease to wail
For from the imperial dome, to where the swain
Rears the lone cottage in the silent dale,
All feel the assault of Fortune's fickle gale;
Art, empire, earth itself, to change are doom'd:
Earthquakes have raised to heaven the humble vale,
And gulfs the mountain's mighty mass entomb'd;
And where the Atlantic rolls, wide continents have bloom'd.'

Before passing on to the Oolite, as developed in Scotland, or rather to our Scotch deposits of the marine Oolite, — for what we call our Wealden is, as I have shown, merely an estuary or lacustrine Oolite, — let me solicit your attention to a few points illustrative of what may be termed the framework of our country. There are two sets of conditions under which land may arise from the ocean. Its hills and [131] plateaus may be formed by the subterranean forces violently thrusting them up, like vast wedges, through the general crust of the earth, and high over the ocean level; or it may be brought up to the light and air en masse by a general elevation over wide areas of the unbroken crust itself; or land may again sink under these two sets of conditions: it may sink in consequence of a breaking up and prostration of its framework to the average level of the crust, — of a striking back, if I may so speak, of the protruded wedges; or it may sink in consequence of a general detression over a wide area of the portion of the crust on which its framework is erected. Thus Scotland might disappear under the waves, either by some violent earthquake convulsion that would strike down its hills and table-lands to the general level of the earth's crust, and of consequence wholly destroy its contour; or it might disappear through a gentle sinking of the area that it occupies, which would leave its general contour unchanged. Were there a depression to take place where it now rises, of but one foot in five hundred over an area a thousand miles square, its highest mountain-summits would be buried beneath the sea, and yet the contour of the submerged land would remain almost identically what it is, — its hills would retain the same relative elevation over its valleys, and its higher table-lands over its lower plains. Now, in the later ages of its history, — in those ages, foi instance, in which the ice-laden ocean of the boulder-clay rose high along its hill-sides, and it existed as a wintry archipelago of islands, there seems to have taken place scarce any change in its framework: the depressions through which it sank, and the elevations through which it rose, seem to have been depressions and elevations of area; and, whether under or over the waves, it continued to retain its general contour. The last great change which affected its frame work, and gave to it a different profile in relation to the general surface of the globe from that which it had borne [132] in the earlier ages, — the change which thrust up its latest- born lines of mountains like wedges through the earth's crust, — was a change which took place a little posterior to that period of its history at which I am now arrived. We find that its last lines of hills disturbed and bore up with them deposits of the Lias and of the Oolite, but of no later formation. The gigantic Ben Nevis and his Anakim brethren of the same group were raising their heads and shoulders through the earth's crust, to form the future landmarks of our country, shortly after the period when the river Lepidoids of the Wealden were disporting in the same brackish tract with the Hybodont sharks of its seas, and its fresh-water Chelonians and marine Plesiosauri met and intermingled in the same neutral rocks of estuary.

The last great paroxysm of upheaval among our Scottish mountains seems to have operated in lines that traversed the country diagonally from nearly south-west by south to north-east by north, — the line indicated by that of the great Caledonian Valley. We find a northern district of considerable extent ploughed in this direction by the great parallel glens traversed by the Spey, the Findhorn, the Nairn, and the Ness. The northern shore of the Moray Firth, too, with that remarkable line of hills which includes the Sutors of Cromarty, pertains to this system, as also the higher mountain range which rises along the coast of Sutherland, and to which the Ord Hill of Caithness belongs. These lines of hills, wherever they have come in contact — as along the shores of the Moray Firth — with beds of the Lias and Oolite, have disturbed and tilted up, at a steep angle, their edges. The hill of Eathie, in the neighbourhood of Cromarty, — a hill of the series in which the two Sutors occur, — has at one place borne up the Lower Lias on its flanks at an angle of eighty; and among the rocks of the Northern Sutor there is a tall precipice of the Old Red Sandstone, with an uptilted deposit of the Lias at its base, whose abrupt, dizzy [133] front, once the haunt of the eagle, and still that of the blue hawk, was evidently, ere the elevation of the series, part of the horizontal platform on which the first Liassic stratum had been deposited. What was a flat submarine bottom then is a steep ivy-mantled precipice now. Across the long deep valleys and mountain ridges of this last line of up heaval in Scotland, — the line to which Ben Nevis, Milfourveny, and the Ord Hill of Caithness belong, and whose period of elevation a high Continental authority, Elie de Beaumont, regards as identical with that of the Mont Pilas and Côte d'Or of France, we find a greatly less continuous, because more interrupted and broken, set of ridges, running in a nearly westerly direction. The firths of Dornoch, Cromarty, and Beauly, with the bays of Munlochy and Urquhart, Loch Oich and Loch Eil, which all strike west wards across the country from off the great diagonal trench of the Caledonian Valley, indicate the direction of this second and earlier line of upheaval. I say earlier line. The hills of the diagonal Ben Nevis line disturbed and broke up the Oolite, whereas the hills of the transverse, or, as I may term it, Ben Wyvis line, disturbed and bore up with them nothing more modern than the Old Red Sandstone. I have described the northern part of the kingdom as consist ing of a great Primary nucleus, surrounded by strata more or less broken, of Old Red Sandstone, Lias, and Oolite.1 Let us now further conceive of that nucleus as a stony field, that had been first ploughed across and fretted into deep furrows and steep mountainous ridges, and then in an after period ploughed diagonally, so as partially to efface the former ploughing, so that only in the direction of the last ploughing do the ridges and furrows remain tolerably entire, — let us, I say, conceive of such a ploughed field, and we shall have a tolerably adequate conception, so far as it goes, of the framework of at least the northern portion of Scotland. [134] In the southern part of the kingdom there is yet another line of elevation exhibited, whose direction from nearly north-east to south-west we find indicated by the nearly parallel lines in which the greater formations of the Lowland counties, from the clay-slates that flank the Grampians, to the Grauwackes of the border districts, sweep across the country. I fear that the homely illustrations which I have to employ in rendering my subject comprehensible, — such as wedges struck upwards from below, — a field first ploughed across and then diagonally, — may have the effect of so reducing my subject in your minds into a mere model, that, through the necessary reduction, more may be lost in expansiveness of feeling than gained by any substitution of clearness of view. There can be little doubt that in the conceptions of mind, as in the collocations of matter, the portable means the small; and that Goethe exercised his wonted shrewdness in remarking, that when the ancients spoke of the unmeasurable earth and the illimitable sea, it was with a profounder feeling than any now exercised by the geographer in a time when every school-girl can tell that the world is round. You will, however, remember, that though my illustrations are small, my subject is large ; and such of my audience as have sailed over the profound depths of Loch Ness, — depths greatly more profound than those of the German Ocean beyond, — and seen those lines of russet mountains, so often capped with cloud, and so often, even at midsummer, streaked with snow, — that rise on either hand, and that enclose from sea to sea that mighty trench which the old unsophisticated Highlander learned to distinguish as the great Glen of Albyn, — when they call up to memory the noble features of the scene, — the long retiring vista on either hand, purple in the far distance; and remember that that vast rectilinear hollow forms but one of the plough furrows of my illustration, — they will see that that with which I am in reality dealing is the sublime of nature, [135] and that even the details of my subject, rightly appreciated, are not suited to lower our conceptions of the wonderful workings of old of Him, who, by processes which science is but now aspiring to comprehend, 'gathered the waters together into one place, that the dry land might appear,' and laid the deep-seated foundation of the mighty hills.

Let us now pass on to the Oolite proper, and its base the Lias, as we find them developed in Scotland. They form but a comparatively small portion of the surface of the country, — not much more, it has been estimated, than sixty square miles; nor can I refer definitely to any marked peculiarity of scenery in the districts in which they occur. The Oolites of Sutherland extend westwards and southwards from the Oid Hill of Caithness to the village of Golspie, a distance of about sixteen miles; and form, under the rugged line of hills against whose flanks they recline, a green narrow strip of low country, that, where not too deeply covered up by débris of the Primary rocks, transported from the in terior during the Pleistocene period, is, for its extent, of great agricultural value, and bears on its cultured surface the rich fields and extensive woods of Dunrobin, the stately castle of the old Earls of Sutherland. Further to the west and south, along the eastern shores of Cromarty and Ross, detached patches of the Lias occur, as at Shandwick, at the Northern Sutor of Cromarty, at the Southern Sutor, and at the Hill of Eathie, — each patch occurring directly opposite, and leaning against, one of the upheaved hills, which, as I have already said, were undoubtedly the agents in raising and bringing it to the surface. The Lias and Oolite also appear on the southern side of the Moray Firth, in the counties of Moray and Banff, but merely as outliers of very limited extent, and sorely broken up or ground down by the denuding Pleistocene agencies. On the western coast of Scotland the Lias may be seen on the mainland at Apple-cross, and on the sides of Loch Aline, opposite the Sound [136] of Mull; while in the inner Hebrides, it forms, with the Oolite, though greatly overflown by trap, the base of the larger part of the island of Mull, of two of the Small Isles, Eigg and Muck, of Raasay and Scalpa, and of large tracts of the eastern and northern half of Skye. At Broadford, in the latter island, the Lias forms the whole of the rich level islet of Pabba, which, lying as at anchor in its quiet bay, reminds one, from its prevailing colour and form, of one of the low, green steamboats of the Clyde. Opposite Pabba, the Liassic deposit sweeps across the mainland of Skye from sea to sea, along a flat valley some two or three miles wide; but while the minute Liassic islet resembles, from the softness of its outline, an islet of England set down in a hill-enclosed bay of the Scottish Highlands, there is nothing English in the scenic character of the Liassic valley. It is a brown and sombre expanse of marsh and moor, studded by blue dreary lochans, interesting, however, to the botanist as habitats of the rare Eriocaulon septangulare. The waste is haunted, too, say the Highlanders, by Ludag, a malignant goblin, not more known elsewhere in Europe than the rare plant that in the last age used to be seen at dusk hopping with immense hops on its one leg, — for, unlike every other denizen of the supernatural world, it is not furnished with two, — and that, enveloped in rags, and with fierce misery in its hollow eye, has dealt heavy blows, it is said, on the cheeks of benighted travellers. Certainly a more appropriate spectre could scarce be summoned to walk at nights over the entombed remains of the old monsters of the Lias than one-legged Ludag, the goblin of the wastes of Broadford. Such, in brief, is a summary of our Oolitic deposits. They occupy, as I have said, but a small portion of the surface of Scotland; and, though coal has occasionally been wrought in them, and though they furnish in several localities supplies of lime and of building stone, their economic importance is comparatively small. But a well-filled volume, — the life-long [137] work of some laborious chronicler, — may have no economic importance in the lower and humbler sense, and may yet form a valuable record of bygone transactions and events suited to delight and instruct throughout all genera tions. And it is thus with the Oolitic deposits of Scotland. Their innumerable strata, closely written 'within and with out' in a language in which every character is an organism, form the leaves of a record in which many of the marvellous existences that flourished during what are geologically the middle ages of our country's history are well and wonderfully preserved. Instead of dissipating your attention by describing at length the fossils of its various deposits, I shall attempt giving you a general idea of the whole under the ordinary division of animal and vegetable, as they have come to my knowledge during the researches of at least thirty years.

In one of its features the Oolitic flora of what is now Scotland must have resembled its flora in the present, or rather in the past age, ere our native pine-woods had yielded to the axe. Trees of the fir or pine division of the Coniferæ, many of them of slow growth and large size, must have formed huge forests in a province of the land of the Oolite which extended from what is now the island of Mull to the Ord Hill of Caithness. The Scuir of Eigg, a subaërial mole of columnar pitchstone, four hundred feet in height, and perched on the ridge of a tall hill, rests on the remains of a prostrated forest, as some of our submarine moles rest on foundations of piles. And of this forest all the trees seem to have consisted of one species, — a conifer of the Oolite now known to the fossil botanist as the Pinites Eiggensis, or Eigg pine. Branches and portions of the trunks of a similar pine are not unfrequent in the Lias of Eathie and Ross; and in shale-beds of the Lower Oolite in the neighbourhood of Helmsdale there occur in abundance fossil trunks and branches, mingled with cones and the narrow spiky leaflets characteristic of the family. I have [138] reckoned in the transverse section of a Helmsdale pine-trunk about two feet in diameter, more than a hundred annual rings. And from the rings and roots of some of the others, its contemporaries, I found that curious insight might be derived respecting the state and condition of vegetable life in the old Scotch woods of the Oolite. In the first place, the annual rings themselves told me, when exposed to transmitted light in the microscope, that the winters of that time gave vegetation as decided a check as our winters now. The tender woody cells were first dwarfed and thickened in their formation by the strengthening of the autumnal cold, and then for a season they ceased to form altogether. But then the spring came, and over the hard concentric line drawn by the chill hand of winter they began to form themselves anew in full-sized luxuriance; and thus, year after year, and for century after century, the process went on. Some of these ancient pine-trees grew in rich sheltered hollows, and acquired bulk so rapidly, that they increased their diameter eight and a half inches in twenty years; others grew so slowly, that they increased their diameter only two and a half inches in forty years. And it is a curious circumstance, that in both those of slower and of more rapid growth we find alternating groups of broader and parrower annual rings, indicating apparently groups of better and worse seasons. Lord Bacon remarks in one of his Essays, — the Essay on the Vicissitude of Things, — that it was a circumstance first observed in the Low Countries (the provinces of the Netherlands), that there were certain meteorological cycles of seasons, — groups of warmer and groups of colder summers, and of more temperate and of less temperate winters, — which periodically came round again. And we have seen not very successful attempts made in our own times to measure these cycles, and reduce them to a formula, from which the nature of the coming seasons might be determined beforehand. But [139] there can be little doubt, — whatever the cause or the order of their occurrence, — that alternations of groups of colder and warmer, better and worse seasons, do occur; and it seems more than probable that, in obedience to some occult law, as little understood in the present age as when its operations were first detected in the Netherlands, Scotland had in the times of the Oolite, as certainly as now, its alternating groups of chill and of genial summers, and of temperate and severe winters. And the well-marked rings of its fossil Coniferæ remain to attest the fact. We can even determine the kind of soil into which a certain proportion of these ancient pines struck root. It was extremely shallow in some localities, and lay over a hard bottom. We find that some of the fossil stumps shot out their roots horizontally immediately as they entered the earth, and sent down no vertical prolongations of the trunk into the subsoil, — an arrangement still common among the roots of trees planted on a shallow stratum of soil resting on a hard bottom. Further, we are still able to ascertain that the hard bottom that underlay the soil in which some of the Oolitic pines of Helmsdale grew was composed of Old Red flagstone, identical in its mineral composition and organic remains with what is now known as Caithness flag.

But let us trace the history of a single pine-tree of the Oolite, as indicated by its petrified remains. This gnarled and twisted trunk once anchored its roots amid the crannies of a precipice of dark-grey sandstone, that rose over some nameless stream of the Oolite, in what is now the north of Scotland. The rock, which, notwithstanding its dingy colour, was a deposit of the Lower Old Red Sandstone, formed a member of the fish-beds of that system, — beds that were charged then, as now, with numerous fossils, as strange and obsolete in the creation of the Oolite as in the creation which at present exists. It was a firm, indestructible stone, covered by a thin, barren soil; and the twisted rootlets of [140] the pine, rejected and thrown backwards from its more solid planes, had to penetrate into its narrow fissures for a straitened and meagre subsistence. The tree grew but slowly: in considerably more than half a century it had attained to a diameter of little more than ten inches a foot over the soil; and its bent and twisted form gave evidence of the life of hardship to which it was exposed. It was, in truth, a picturesque rag of a tree, that for the first few feet twisted itself round like an overborne wrestler struggling to escape from under his enemy, and then struck out at an abrupt angle, and stretched itself like a bent arm over the stream. It must have resembled, on its bald eminence, that pine-tree of a later time described by Scott, that high above 'ash and oak,'

'Cast anchor in the rifted rock,
And o'er the giddy chasm hung
His shatter'd trunk, and frequent flung,
Where seem' d the cliffs to meet on high,
His boughs athwart the narrow'd sky.'

The pines of our Scotch Oolite — some of them, as I have shown, or rather as my specimens show, of exceedingly slow growth — are suggestive of a temperate, if not severe climate. The family of their contemporaries, however, to which I must next refer as not less characteristic of the flora of this ancient time than the coniferæ themselves, is now to be found in a state of nature in only the warmer regions of the earth, and can be studied in this part of the world only in our conservatories and greenhouses. It is known to the botanist as the Cycadaceous family; and at least two of its genera, Cycas and Zamia, we find well represented in the Oolitic deposits of Scotland. In the Zamia, a cylindrical, squat, scale-covered pedestal is fringed along its upper edge by a ring of long pinnate leaves, that radiate outwards like the spokes of a wheel from the nave; and, placed on the centre of the pedestal, there is, when the plant is in fruit, a handsome cone. The tout ensemble is as if a pine-apple, with the pot in which it grew, and with its leaves arranged like a ruff round its stem, formed altogether but one plant. The Cycas is usually taller than [142] Zamia; the leaves also, of the compound pinnate character, are smaller and more bushy; and it resembles, as a whole, a decapitated palm, with a coronal of fern bound atop, as if to conceal the mutilation. With these Cycadaceæ there flourished in the marshes of the period plants of a family still widely spread over the various climatal zones, but which now attain to any considerable size only within the tropics. I refer to the Equisetaceæ, or horse-tail family, — slim, cone-crowned plants, fringed with green verticillate leaves, or branches rather, and which in this country are rarely thicker than a quill, or rarely exceed eighteen inches in height, but which have been found in the intertropical swamps of South America fifteen feet high, and three inches in circumference at the lower part of the stem. In the Oolite of Scotland, a well-marked, long-extinct species, the Equisetum columnare must have attained, judging from the thickness of the stem, which is sometimes fully three inches in diameter, to at least thrice the size of its tropical congeners. As shown by its remains, which occur in the lignite shales of Brora, it must have been a plant of con siderable elegance of form, encircled at each joint at some of the specimens by torus-like mouldings grooved crosswise, traversed in the spaces between by longitudinal markings, delicately punctulated, and gracefully feathered from root to pointed top by its verticillate garlands of spiky leaves. The Lycopodiaceæ or club-moss family, existing in rather massier and more arboraceous forms than now, though reduced in a greatly more than equal degree from their gigantic congeners of the Coal Measures, were also abundant (as shown by the rocks of Helmsdale) in the Oolitic flora of Scotland; and with these there mingled various genera, consisting of numerous species of well-marked ferns. Ferns, indeed, so far as we yet know, may be regarded as forming the base, and pines the apex, of the terrestrial Oolitic flora; and between these two extremes most of its [143] other productions seem to have ranged. The Cycadaceæ possess certain characters which belong to both : they are, if I may so speak, fern-pines, with, in some instances, a peculiarity of aspect which seems also to ally them to the palms. Again, the Lycopodiaceæ, intermediate between the mosses and the ferns, may be described as fern-mosses, with a peculiarity of aspect in some of the Oolitic species that seems to ally them to the pines. And the Equisetaceæ belong to at least the same sub-class as the ferns, — the Acrogens. The Palmæ, as shown by the English deposits, were also present in the Golitic flora: nor is it probable that a species of vegetation which the old Yorkshire of the Oolite possessed, the old Scotland of the Oolite should have wanted; though I have not yet succeeded in finding the remains of palms in any of our Scotch deposits.

The animal productions of our country during this early period were divided, like those of the present time, into the four great Cuvierian divisions, all of which we still find in a fossil state in our rocks. Corals akin to the tropical forms, — some of them of great size, — with star-fishes and sea-eggs, represent the radiata; a fossil lobster which occurs in the Lias of Cromarty somewhat meagrely represents the articulata. The shelled mollusca we find very largely represented in almost all their classes and families, from the high Cephalopods to the low Brachipods; and in this division the peculiar character of the Oolitic system is more strongly impressed than even on its flora. Its corals, though many of them of great size, as I have just said, and of elegant form, might almost pass for those of the intertropical seas of the present day; nor are its crustacea and insects, even where best preserved, as in the Oolites of England, of a character widely different from those which still exist. But by much the larger part of its mollusca bear the stamp of a fashion that has perished. It is chiefly, however, in its molluscas of the first class, — the Cephalopods, — creatures [144]  of a high standing in their division, and represented in the present day by the nautilus and the cuttle-fish, that we recognise in its fullest extent this extinct peculiarity of type and form. Its Brachipods, chiefly terebratulæ, not unfrequent in the Sutherland Oolites, and in the Lias of Cromarty and Skye, — its periwinkles, whelks, aviculæ, pinnæ, pectens, oysters, and mussels, few of them wanting in any of our Scotch Liassic or Golitic deposits, and many of them very abundant, though all specifically extinct, present us, though with a large admixture of strange and exotic forms, with many other forms with which, generically at least, we are familiar. But among the Cephalopods all is strange and unwonted; and their vast numbers — greater at this period of the world's history than in any former or any after time — have the effect of impar ting their own unfamiliar character to the whole molluscan group of the Golite. I need but refer to two families of these, — the Belemnite family and the family of the Ammonites; both of them so remarkable, that they attracted in their rocks the notice of the untaught inhabitants of both England and Scotland, and excited their imagination to the point at which myths and fables are produced, long ere Geology existed as a name or was known as a science. The Belemnites are the old thunder-bolts of the north of Scotland, that, in virtue of their supposed descent from heaven, were deemed all potent in certain cases of bewitchment and the evil-eye; and the Ammonites are those charmed snakes of the medkeval legend,

        'That each one
Was changed into a coil of stone,
When holy Hilda prayed.'

The first great division of the animal kingdom, the vertebrata, was represented in Scotland during the Oolitic period by fishes and reptiles. Its fishes seem to have been restricted to two orders, — that placoid order to which the existing sharks belong, and that ganoid order, now well-nigh worn out in creation, to which the Lepidosteus of the North American lakes and rivers belongs, and to which I incidentally referred in connexion with the Lepidotus of the Weald. I have found in the island of Eigg beds of a limestone composed almost entirely of fossil shells, which were strewed over with the teeth of an extinct genus of sharks, the Hybodonts; and I have seen the dorsal spines of the same placoid division occasionally occurring among the Oolites of Sutherland and the Lias of Eathie. And scales, cerebral plates, and in some instances considerable portions of individuals of the ganoidal species, glittering in the enamel to which they owe their name, occur in all the Oolitic deposits of Scotland. Of our Scottish reptiles of the Oolite we have still a good deal to learn. I was fortunate enough in 1844 to find in a deposit of Eigg, and again at Helmsdale, in i 849, the remains of several of its more characteristic Enaliosaurs, or bepaddled reptiles of the sea; at Helmsdale I found vertebral joints of the Ichthyosaurus in a conglomerate lower in the Oolite; and in Eigg, in a [146]  stratum composed of littoral univalves, vertebral joints, phalanges, and portions of the humerus and of the pelvic arch of Plesiosaurus, together with the limb-bones of crocodileans, and fragments of the carapace of a tortoise. Previous, however, to even the earlier date of my discoveries, the tooth of a Saurian had been found in the Sutherlandshire Oolite by Mr. (now Sir Roderick) Murchison, and the limb-bone of a Chelonian with a sauroid vertebra, in the outlier of the Morayshire Weald at Linksfield. My collection, however, though still very inadequate in this department, contains, in quantity at least, and, I am disposed to think, in variety also, some eight or ten times more of the reptilian remains of Scotland, during the Secondary ages, than all the other collections of the kingdom. They at least serve to demonstrate that the Oolitic period in what is now our country, was, as in England and on the Continent, a period of huge and monstrous reptiles, — that the bepaddled Enaliosaurs, the strange reptilian predecessors of the Cetacea, haunted our seas in at least two of their generic forms, — that of the Ichthyosaur and that of the Plesiosaur; that our rivers were frequented by formidable crocodiles; and that tortoises of various perished species lived in our lakes and marshes, or, according to their natures, disported on the drier grounds. Nor is it probable that the other reptilian monsters of the time, the contemporaries of these creatures in England, would have been wanting here. We may safely infer that flocks of Pterodactyles, — reptiles mounted on bat-like wings, and as wild and monstrous in aspect and proportion as romancer of the olden time ever feigned, — fluttered through the tall pine-forests, or perched on the cycadeæ and the tree-ferns; that the colossal Iguanodon and gigantic Hykeosaurus browsed on the succulent equisetaceæ of the low meadows; that the minute Amphitherium, an insectivorous mammal of the period, lodged among the ferns on the drier grounds, where extinct grass-hoppers [147]  chirped throughout the long bright summer, and antique coleoptera burrowed in the sand; and that far off at sea there were moments when the sun gleamed bright on the polished sides of the enormous Cetiosaurus, as it rose from the bottom to breathe. But I must close this part of my subject, — the Scottish flora and fauna of the Oolite, — on which my narrow limits permit me, as you see, to touch at merely a few salient points, — with two brief remarks : — First, So rich was its flora, that its remains formed on the east coast of Sutherland a coal, or rather lignite field, so considerable that it was wrought for greatly more than a century, — at one time to such effect, that during the twelve years which intervened between 1814 and 1826, no fewer than seventy thousand tons of coal were extracted from one pit. Second; The strange union which we find in the same beds of trees that seem to have languished under chill and severe skies, with plants, corals, and shells of a tropical or semi-tropical character, need not be regarded as charged with aught like conflicting evidence respecting the climatal conditions of the time. Climate has its zones marked out as definitely by thousands of feet on our hill-sides as by degrees of latitude on the surface of the globe; and if the Scotland of the Oolitic period was, as is probable, a mountainous country traversed by rivers, productions of an intertropical, and of even a semi-arctic, character, may have
been not only produced within less than a day's journey of each other, but their remains may have been mingled by land-floods, as we find the huge corals of Helmsdale blent with its slow-growing pines, among the débris of some littoral bed. The poet's exquisite description of Lebanon suggests, I am disposed to think, the true reading of the enigma : —

'Like a glory the broad sun
Hangs over sainted Lebanon,
Whose head in wintry grandeur towers,
And whitens with eternal sleet; [148]
While summer, in a vale of flowers,
Is sleeping rosy at his feet.'

'Of dreadful beasts, that, when they drew to hande,
Half-flying and half-floating, in their haste,
Did with their largeness measure o'er much lande, [149]
And made wide shadow under bulksome waist,
As mountain doth the valley overcaste;
And trailing scaly tails did rear afore
Bodies all monstrous, horribill, and vaste.'

We stand on an elevated wood-covered ridge, that on the one hand overlooks the blue sea, and descends on the other towards a broad river, beyond which there spreads a wide expanse of a mountainous, forest-covered country. The higher and more distant hills are dark with pines; and, save that the sun, already low in the sky, is flinging athwart them his yellow light, and gilding, high over shaded dells and the deeper valleys, cliff, and copse, and bare mossy summit, the general colouring of the background would be blue and cold. But the ray falls bright and warm on the rich vegetation around us, — tree ferns, and tall club-mosses, and graceful palms, and the strangely-proportioned cycadaceæ, whose leaves seem fronds of the bracken fixed upon decapitated stumps; and along the banks of the river we see tall, intensely green hedges of the feathered equisetaceæ. Brown cones and withered spiky leaves strew the ground; and scarce a hundred yards away there is a noble Araucarian, that raises, sphere-like, its proud head more than a hundred feet over its fellows, and whose trunk, bedewed with odoriferous balsam, glistens to the sun. The calm stillness of the air makes itself faintly audible in the drowsy hum of insects; there is a gorgeous light-poised dragon-fly darting hither and thither through the minuter gnat-like groups: it settles for a moment on one of the lesser ferns, and a small insectivorous creature, scarce larger than a rat, issues noiselessly from its hole, and creeps stealthily towards [150] it. But there is the whirr of wings heard overhead, and lo! a monster descends, and the little mammal starts back into its hole. 'Tis a winged dragon of the Oolite, a carnivorous reptile, keen of eye and sharp of tooth, and that to the head and jaws of the crocodile adds the neck of a bird, the tail of an ordinary mammal, and that floats through the air on leathern wings resembling those of the vampire bat. We have seen, in the minute rat-like great creature, one of the two known mammals of this vast land of the Oolite, — the insect-eating Amphitherium; and in the flying reptile, one of its strangely organized Pterodactyls.

But hark! what sounds are these ~ Tramp, tramp, tramp, — crash, crash. Tree-fern and club-moss, cycas and zamia, yield to the force and momentum of some immense reptile, and the colossal Iguanodon breaks through. He is tall as the tallest elephant, but from tail to snout greatly more than twice as long; bears, like the rhinoceros, a short horn on his snout; and has his jaws thickly implanted with saw-like teeth. But, though formidable from his gieat weight and strength, he possesses the comparative inoffensiveness of the herbivorous animals; and, with no desire to attack, and no necessity to defend, he moves slowly onward, deliberately munching, as he passes, the succulent stems of the cycadaceæ. The sun is fast sinking, and, as the light thickens, the reaches of the neighbouring river display their frequent dimples, and ever and anon long scaly backs are raised over its surface. Its numerous crocodileans are astir; and now they quit the stream, and we see its thick hedge-like lines of equisetaceæ open and again close, as they rustle through, to scour, in quest of prey, the dank meadows that line its banks. There are tortoises that will this evening find their protecting armour of carapace and plastron all too weak, and close their long lives of centuries. And now we saunter downwards to the shore, and see the ground-swell breaking white in the calm against ridges of coral scarce less white. The [151] shores are strewed with shells of pearl, — the whorled Ammonite and the Nautilus; and amid the gleam of ganoidal scales, reflected from the green depths beyond, we may see the phosphoric trail of the Belemnite, and its path is over shells of strange form and name, — the sedentary Gryphæa, the Perna, and the Plagiostoma.
But lo! yet another monster. A snake-like form, surmounted by a crocodilean head, rises high out of the water within yonder coral ledge, and the fiery sinister eyes peer inquiringly round, as if in quest of prey. The body is but dimly seen; but it is short and bulky compared with the swan-like neck, and mounted on paddles instead of limbs; so that the entire creature, wholly unlike anything which now exists, has been likened to a boa-constrictor threaded through the body of a turtle. We have looked upon the Plesiosaurus. And now outside the ledge there is a huge crocodilean head raised; and a monstrous eye, huger than that of any other living creature, — for it measures a
full foot across, — glares upon the slimmer and less powerful reptile, and in an instant the long neck and small head disappear. That monster of the immense eye, — an eye so constructed that its focus can be altered at will, and made to comprise either near or distant objects, and the organ it self adapted either to examine microscopically or to explore as a telescope, — is another bepaddled reptile of the sea, the Ichthyosaurus or fish-lizard. But the night comes on, and the shadows of the woods and rocks deepen: there are uncouth sounds along the beach and in the forest; and new monsters of yet stranger shape are dimly discovered moving amid the uncertain gloom. Reptiles, reptiles, reptiles, — flying, swimming, waddling, walking ; — the age is that of the cold-blooded, ungenial reptile; and, save in the dwarf and inferior forms of the marsupials and insectivora, not one of the honest mammals has yet appeared. And now the moon rises in clouded majesty; and now her red wake [152] brightens in one long strip the dark sea; and we may mark where the Cetiosaurus, a sort of reptilian whale, comes into view as it crosses the lighted tract, and is straightway lost in the gloom. But the night grows dangerous, and these monster-haunted woods were not planted for man. Let us return then to the safer and better furnished world of the present time, and to our secure and quiet homes.