The Poet Delta (Dr. Moir) — His Definition of Poetry — His Death — His Burial-place at Inveresk — Vision, Geological and Historical, of the Surrounding Country — What it is that imparts to Nature its Poetry — The Tertiary Formation in Scotland — In Geologic History all Ages contemporary — Amber the Resin of the Pinus succinifer — A Vegetable Production of the Middle Tertiary Ages — Its Properties and Uses — The Masses of Insects enclosed in it — The Structural Geology of Scotland — Its Trap Rock — The Scenery usually associated with the Trap Rock — How formed — The Cretaceous Period in Scotland — Its Productions — The Chalk Deposits — Death of Species dependent on Laws different from those which determine the Death of Individuals — The Two great Infinites.

THE members of the Philosophical Institution of Edinburgh enjoyed the privilege last season of listening to one of the sweetest and tenderest of modern British poets eloquently descanting on the history of modern British poetry. Rarely had master established for himself a better Claim to teach. And, regarding the elegant volume produced on that occasion, so exquisite in its taste and so generous in its criticisms, it may justly be said that perhaps its only, at all events its gravest defect, is the inevitable one that, in exhibiting all that during the bypast generation was most characteristic and best in the poesy of our country, it should have taken no cognizance of the poetry of Delta. Dr. Moir had just finished his course, but his volume had not yet appeared, when, urged by a friend, I perhaps too rashly consented to contribute two lectures to a course then delivering in the native town of the poet; and in one of these I expressed the conviction to which I gave utterance last season in this place, that there is no incompatibility between the pursuit of geologic science and a genial [082] development of the poetic faculty. Dr. Moir had honoured my address with his presence ; he had listened with apparent attention to a view very much opposed, as I was told after the breaking up of the meeting, to one which he himself had promulgated to the Institution only a few weeks before; and on the publication of his little volume he politely sent me a copy, accompanied by a kind note, in which he referred to the point apparently at issue between us as involving rather a seeming than a real difference. 'Our antagonism respecting the relations of poetry and science,' he said, 'is, I doubt not, much more apparent than real, and arises simply from the opposite aspects in which we have regarded the subject.' I read his work with interest; and at first deemed the difference somewhat more than merely apparent. I found the lecturer speaking of 'staggering blows' inflicted on the poetry of the age by science in not a few formidably prosaic shapes, — in the shape, among the rest, of 'geological exposition;' and of 'rocks stratified by the geologists as satins are measured by mercers,' and, in consequence, no longer redolent of that emotion of the sublime which was wont to breathe forth of old from broken crags and giddy precipices. But his definition of poetry re-assured me, and set all right again. 'Poetry,' he said, 'may be defined to be objects or subjects seen through the mirror of imagination, and descanted on in harmonious language; and if so, it must be admitted that the very exactness of knowledge is a barrier to the laying on of that colouring by which facts can be invested with the illusive hues of poetry. Wherever light penetrates the obscure and illuminates the uncertain, we may rest assured that a demesne has been lost to the realms of imagination.' Now, if such be poetry, I said, and such the conditions favourable to its development, the poets need be in no degree jealous of the geologists. The stony science, with buried creations for its domains, and half an eternity [083] charged with its annals, possesses its realms of dim and shadowy fields, in which troops of fancies already walk like disembodied ghosts in the old fields of Elysium, and which bid fair to be quite dark and uncertain enough for all the purposes of poesy for centuries to come.

Alas! only a few weeks after, amid hundreds of his sorrowing friends and townsmen, I followed the honoured remains of the poet to the grave; and heard, in that old picturesque burying-ground which commands on its green ridge the effluence of the Esk, the shovelled earth falling heavy on the coffin-lid. It was a lovely day of chequered shadow and sunshine; and the wide firth slept silently in the calm, with a dream-like spectrum of the heavens mirrored on its bosom. From the sadness of the present my thoughts let themselves out upon the past. I stood among the groves on a grassy mound which had been reared by the old Roman invader greatly more than a thousand years before; and I bethought me how, on visiting the place a few twelvemonths previous, for the first time, I had first of all sought out the burying-ground of the family of the deceased, — a spot endeared to every lover of poesy by those tenderest and sweetest of 'domestic verses' which show how truly, according to Cowper, 'the poet's lyre' had been 'the poet's heart;' and how I had next set myself to trace, as next in interest, the remains of that stern old people whose thirst of conquest and dominion had led them so far. And lo! like a dream remembered in a dream, as the crowd broke up and retired, the visions of that quiet day were again conjured up before me, but bearing now a felt reference to the respected dead, and accompanied by the conviction that, had we been destined to meet, and to compare at length our respective views, we should have found them essentially the same.

On that rising ground, so rich in historic associations, both Somerset and Cromwell had planted their cannon, and [084] it had witnessed the disaster at Pinkie, and the headlong flight of the dragoons of Cope. But, passing over the more recent scenes, the vision of a forest-covered country rose before me, — a vision of the ancient aboriginal woods rising dusky and brown in one vast thicket, from the windings of the Esk to the pale brow of the Pentlands. Nor was the landscape without its human figures. The grim legionaries of the Proconsul of Augustus were opening with busy axes a shady roadway through the midst; and the incessant strokes of the axe and the crash of falling trees echoed in the silence throughout the valley. And then there arose another and earlier vision, when the range of semicircular heights which rise above the ancient Saxon borough, with its squat tower and antique bridge, existed as the coast line, and the site of the town itself as a sandy bay, swum over by the sea-wolf and the seal; and the long ridge now occupied by garden and villa, church and burying-ground, as a steep, gravelly bar, heaped up in the vexed line, where the tides of the river on the one hand contended with the waves of the firth on the other; and the Esk, fed by the glaciers of the interior, whose blue gleam I could mark on the distant Lammermuirs and the steeper Pentlands, rolled downwards, a vast stream, that filled from side to side the ample banks which, even when heaviest in flood, it scarce half-fills now; while a scantier and dingier foliage than before, composed chiefly of taper spruce and dark pine, rough ened the lower plains, and flung its multitudinous boughs athwart the turbid and troubled eddies. And then there arose yet other and remoter scenes. From a foreground of weltering sea I could mark a scattered archipelago of waste uninhabited islands, picturesquely roughened by wood and rock; and near where the Scottish capital now stands, a submarine volcano sent forth its slim column of mingled smoke and vapour into the sky. And then there rose in quick succession scenes of the old Carboniferous [085] forests: long withdrawing lakes, fringed with dense thickets of the green Calamite, tall and straight as the masts of pinnaces, and inhabited by enormous fishes, that glittered through the transparent depths in their enamelled armour of proof; or glades of thickest verdure, where the tree-fern mingled its branch-like fronds with the hirsute arms of the gigantic club-moss, and where, amid strange forms of shrub and tree no longer known on earth, the stately Araucarian reared its proud head two hundred feet over the soil; or yet again, there rose a scene of coral bowers and encrinal thickets, that glimmered amid the deep green of the ancient ocean, and in which, as in the groves sung by Ovid, the plants were sentient, and the shrinking flowers bled when injured. And, last of all, on the further limits of organic life a thick fog came down upon the sea, and my excursions into the remote past terminated, like the voyage of an old fabulous navigator, in thick darkness. Each of the series of visions, whether of the comparatively recent or the remote past, in which I at that time indulged, had employed the same faculties and gratified the same feelings; and though, in surveying the stuff out of which they had been sublimed, I could easily say where the historic ended and the geologic began, no corresponding line indicated in the visions themselves where the poetry ended and the prose began. The visions, whether historic or geologic, 'were of imagination all compact.' They all involved the same processes of mind — though, of course, in this instance, mind of a humbler order and ruder texture — as those exhibited in the sweet and fragrant verse of the poet himself, — as those exercised, let me say, in his vision on 'Mary's Mount,' when, with quiet graves above, and surrounded by quiet fields, he saw the contending hosts of a former day thronging the lower ground, and,

'With hilt to hilt, and hand to hand,
The children of our mother land
To battle came;'
[086] or when he called up, after the lapse of half a lifetime, how when, in a wintry morning, he had journeyed before day break, a happy boy, along the frozen Esk, and saw
'In the far west the Pentland's gloomy ridge
Belting the pale blue sky, whereon a cloud,
Fantastic, grey, and tinged with solemn light,
Lay like a dreaming monster, and the moon,
Waning, above its silvery rim upheld
Her horns, as 'twere a spectre of the past.'
I shall continue to hold, therefore, that there was no real difference between the views of the poet and those which I myself entertain but that, as he himself well expressed it, our 'apparent antagonism arose simply from the opposite aspects in which we had viewed the subject.' He had been thinking of but stiff diagrams and hard names, — of dead strata measured off, in 'geological exposition,' by the yard and the mile, and enveloped in the obscuring folds of a Babylonish phraseology: while I, looking through the crooked characters and uncouth sounds in which the meanings of the science are locked up, to the meanings themselves, was luxuriating among the strange wild narratives and richly poetic descriptions of which its pregnant records consist.

What is it, let me ask, that imparts to Nature its poetry?  It is not in Nature itself; it resides not either in dead or organized matter, — in rock, or bird, or flower; 'the deep saith, It is not in me, and the sea saith, It is not in me.' It is in mind that it lives and breathes: external nature is but its storehouse of subjects and models; and it is not until these are called up as images, and invested with 'the light that never was on land or sea,' that they cease to be of the earth earthy, and form the ethereal stuff of which the visions of the poet are made. Nay, is it not mainly through that associative faculty to which the sights and sounds of present nature become suggestive of the images of a nature not present, but seen within the mind, that the landscape pleases, [087] or that we find beauty in its woods or beside its streams, or the impressive and the sublime among its mountains and rocks? Nature is a vast tablet, inscribed with signs, each of which has its own significancy, and becomes poetry in the mind when read; and geology is simply the key by which myriads of these signs, hitherto undecipherable, can be unlocked and perused, and thus a new province added to the poetical domain. We are told by travellers, that the rocks of the wilderness of Sinai are lettered over with strange characters, inscribed during the forty years' wanderings of Israel. They testify, in their very existence, of a remote past, when the cloud-o'ershadowed tabernacle rose amid the tents of the desert; and who shall dare say whether to the scholar who could dive into their hidden meanings they might not be found charged with the very songs sung of old by Moses and by Miriam, when the sea rolled over the pride of Egypt? To the geologist every rock bears its inscription engraved in ancient hieroglyphic characters, that tell of the Creator's journeyings of old, of the laws which He gave, the tabernacles which He reared, and the marvels which He wrought, — of mute prophecies wrapped up in type and symbol, — of earth gulfs that opened, and of reptiles that flew, — of fiery plagues that devastated on the dry land, and of hosts more numerous than that of Pharaoh, that 'sank like lead in the mighty waters;' and, having in some degree mastered the occult meanings of these strange hieroglyphics, we must be permitted to refer, in asserting the poetry of our science, to the sublime revelations with which they are charged, and the vivid imagery which they conjure up. But our history lags in its progress, while we discuss the poetic capabilities of the study through which its records are read and its materials derived.

In the deposits of that Tertiary division of the geologic formation which represents in the history of the globe the period during which mammals began to be abundant, and in [088] which the great Cuvier won his laurels, Scotland is one of the poorest of European countries. Save for the comparatively recent discovery of Tertiary beds in the island of Mull by a nobleman fitted by nature either to adorn the literature or extend the science of his country, the geological historian would have to pass direct from the Pleistocene beds, with their grooved and polished pebbles and their semi-arctic shells, to the Chalk fossils of Banif and Aberdeen. But the discovery of his Grace the Duke of Argyll furnishes us with an interesting glimpse of a middle period widely different in its character from either the Cretaceous system or the boulder-clay. In the island of Mull, in a headland that rises about 130 feet over the sea, there occur, interposed between thick beds of trap, three comparatively thin beds of a grey arenaceous shale, charged with fossil leaves, as beautifully spread out, and with their ribs and veins as distinctly visible, as if they had been preserved in the herbarium of a botanist. Most of them belong to extinct species of existing families of dicotyledonous trees, such as the plane and the buckthorn, mingled, however, with narrow linear leaves of cone-bearing trees, which are supposed to belong, in this instance, to a species of yew, and with what seem the fronds of fern and the stems of equisetaceæ. Some of the beds of coal which have been long known to occur among the traps of the island of Mull are regarded by the Duke of Argyll as prolongations of these Tertiary leaf-beds, so mineralized by some metamorphic action as to have lost the organic structure. There must have been vast accumulations of leaves ere they could have yielded beds of coal. The middle or second bed of the three his Grace describes as peculiarly rich in the leafy impressions of this ancient period; and I need scarce say how suggestive the glimpse is which is furnished us by these buried layers of the foliage of Tertiary forests in Scotland, of which no other known memorial remains. You all remember Coleridge's fine comparison of the sorely-worn sails [089] of the vessel in which the ancient mariner performed his voyage of peril and prodigy, to

'Brown skeletons of leaves that lay
The forest brook along,
When the ivy tod is heavy with snow,
And the owlet whoops to the wolf below ;'

and you must have often marked the extreme delicacy of those deposited leaves, macerated during the winter season at the bottom of some woodland pool, which suggested the poet's simile. In that Tertiary period to which the leaf-beds of Mull belong, it would seem that extensive forests, chiefly of deciduous trees, shed year after year their summer coverings of leaves, some of which fell, and some of which were blown by the autumnal gusts, into the streams of the country, and were swept down by the current to lakes or estuaries, where they lay gradually resolving into such brown skeletons as caught the eye of Coleridge. We learn further, that there were forces active at the time, of which at any later period we have had no examples in the British islands. One of the leaf-beds described by his Grace is overlaid by a bed of volcanic ashes or tuff several feet thick; another by a bed of similar ashes mixed with chalk flints, twenty feet thick; and yet another — the topmost layer — bears over it a bed of overflowing columnar basalt, forty feet thick. The volcanic agencies were active in what is now Scotland during the ages of its Tertiary forests.

The only Tertiary fossils of Scotland yet discovered are these forest and fern leaves of the Mull deposits. Their place in the great geologic division to which they belong is still definitely to fix; but some of our higher geologists are, I find, disposed to refer them to the second Tertiary or Miocene epoch, though with considerable hesitation. They belong, it is probable, to a period not very widely removed from that of the richly fossiliferous Marlstone of Œningen, on the banks of the Rhine, with its vast abundance of [090] plants, chiefly dicotyledonous, — of fishes specifically different from those which now exist, but of the existing genera, — of a fox, which only the comparative anatomist can distinguish from the recent species of this country, — and of reptiles generically akin to those of the United States. It is a curious fact that, both in its animal and vegetable productions, that part of the New World which borders upon the Atlantic in the temperate zone, from Carolina to the mouth of the St. Lawrence, still presents very much the appearance which was presented by the flora and fauna of Europe during the later Tertiary periods. It has been often remarked, in reference to human manners and the progress of civilisation, that all ages of the world may be regarded as contemporary. Man is still, in many of the South Sea Islands, what he was in our own country previous to the times of the Roman invasion; and there are provinces in Spain and Portugal in which neither the people nor the clergy have got beyond the semi-barbarism of the Middle Ages. Curiously enough, in geologic history also, though in a narrower and more restricted sense, all ages are contemporary. The Galapagos have their age of reptiles, New Zealand its age of birds, and New Holland its age of marsupial quadrupeds. These countries bear now, in not a few particulars, the character of the Oolitic period in our own country. Again, on the eastern coasts of North America we are presented with a vegetation greatly resembling that of some of the later Tertiary periods; and of several of its animals the type is still more ancient. America, though emphatically the New World in relation to its discovery by civilized man, is, at least in these regions, an old world in relation to geological type; and it is the so-called Old World that is in reality the new one. 'If we compare,' says Professor Agassiz, in his late admirable work, Lake Superior, — 'if we compare a list of the fossil trees and shrubs from the Tertiary beds of Œningen with a catalogue [091] of the trees and shrubs of Europe and North America, it will be seen that the differences scarcely go beyond those shown by the different floras of these continents under the same latitudes. But what is quite extraordinary and unexpected is the fact, that the European fossil plants of that locality resemble more closely the trees and shrubs which grow at present in the eastern parts of North America, than those of any other part of the world; thus allowing us to express correctly the difference between the opposite coasts of these continents, by saying that the present eastern American flora, and, I may add, the fauna also, have a more ancient character than those of Europe. The plants, especially the trees and shrubs growing in our days in the United States, are, as it were, old-fashioned; and the characteristic genera Lagoings, Chelydra, and the large Salamanders, with permanent gills, that remind us of the fossils of Œningen, are at least equally so : they bear the marks of former ages.' This interesting fact, — vouched for by assuredly no mean authority, — may enable us to conceive of the general aspect of our country, so far at least as its appearance depended on its vegetation, towards the close of the Miocene period. Old Scotland exhibited features in that age greatly resembling those presented to the Puritan Fathers by the forest-covered shores of New England little more than two centuries ago. But no family of man dwelt in its solitary woods; and, as shown by its widely spread deposits of trap-tuff, and its vast beds of over lying basalt, broken by faults and shifts, its ancient volcanoes had not yet died out, and it must have had its frequent earthquake-agues and shaking-fits.

There is, however, another witness besides the leaf-beds of the island of Mull, which we may properly call into court to give evidence regarding the Tertiary period in Scotland. It is known that from a very early time masses of amber have been occasionally furnished by the north-eastern shores [092] of the kingdom, in especial by that extensive tract of coast which stretches from the Buchan-ness to the Firth of Tay; and the geologist now recognises amber as a vegetable production of the Middle Tertiary ages. It is the resin of an extinct pine, which the fossil botanist has only of late learned to term the Pinus succinifer, or amber pine, but which the Prussian peasantry, who gather amber on the southern shores of the Baltic, used for ages to associate with this substance, from its occurrence in a fossil state in the same beds as amber wood. The ornamental character of this precious resin seems to have been appreciated by the native Scotch at an early period: beads of amber have been found in the old sepulchral barrows of the kingdom. Its value, however, as we learn from the first notice of it which occurs in our written history, — that of Hector Boece, — has not been always appreciated. After describing it, not very inadequately, as 'ane maner of goum or electuar, hewit like gold, and sa attractive of natur, that it drawis stra, flax, or hemmes of claethis to it in the samen maner as does an adamant stone grow,' he goes on to say that 'twa year afore the comm af [his] buke to licht (1524) thair arrivit an gret lompe of this goum in Buchquhane, als meikle as an hens; and wes brocht hame by the herdes quhilk wer kepand thair bestis, to thair housis, and cassin in the fere. And becaus they fand an smell and odour thairwith, they scha to thair maister that it wes garand for the insens that is maid in the kirkes. Thair maister wes ane rud man as thay wer; and tuk bot ane litell part thairof, and left the remanent part behind him as mater of litell effect. All the parts of this goum, quhen it wes broken, wes of hew of gold, and schone lyke the licht of an candell. The maist part of this goum or electuar wes destroyit be rud peple afore it cam to any wise mannis eirs; of quhome may be verifyet the proverb, "The sow cares not for balme." Als sone as I wes advertisit thairof, I maid sic diligence that ane pairt of it [093] was brocht me at Aberdene.' I may add to this notice of the old chronicler, that up to a comparatively recent period, ornaments of amber, especially amber beads of large size, or, as they were termed by our ancestors, 'lam our beads,' were highly valued by the humbler Scotch. That mysterious attractive property which resided in this gem-like resin, and which has since been found pregnant with that wonderful science to which the substance has given its Greek name, electrum, threw a halo of mystery around it, that served to enhance its native beauty. The Laird of Dumbiedykes was, it must be confessed, neither a very fervent nor very poetical lover; but a lover he was; and yet he could find nothing more apt with which to compare the eyes of his mistress, when turned upon him in her gratitude, than to beads of amber. 'Dinna ye think,' said the laird, 'puir Jeanie's e'en, wi' the tears in them, glanced like lamour beads, Mr. Saddletree'?'

To the geologist this precious gum of the Tertiary ages is fraught with a peculiar interest, from the circumstance that it forms the best of all matrices for the preservation of organisms of the more fragile kinds. Mosses, fungi, and liverworts, are plants of so delicate a structure, that they are rarely or never preserved in shale or stone; but specimens of all three have been found locked up in amber in a state of the most perfect keeping. And, besides containing fragments of the pine which produced it, it has been found to contain minute pieces of four other species of pine, with bits of cypresses, yews, junipers, oaks, poplars, beeches, etc., — in all, forty-eight different species of shrubs and trees, which must have flourished in the forests where it grew, and which, viewed in the group, may be regarded as constituting,' says Professor Gdppert, 'a flora of a North American character.' You will of course remark how directly this evidence bears on that of Professor Agassiz. The most remarkable organisms of the amber, are, however, its insects, — a kind of [094] fossils suggestive of a very different poetry from that which Pope elaborated from them in his well-known simile

Pretty in amber to observe the forms
Of hairs, or straws, or dirt, or grubs, or worms
The things, we know, are neither rich nor rare,
But wonder how the mischief they got there!'
Fossil insects occur in both the Secondary and Palæozoic divisions, but rarely indeed in a state of suflicient entireness to enable the entomologist to distinguish their species. Even in classing them into families and genera, our best writers on the subject, such as the Rev. Mr. Brodie, confess that some of the number are very imperfectly made out. In the amber, on the contrary, even the most delicate ephemeræ that ever sported for a single summer evening in a forest glade, and then perished as the night came on, are preserved in a state of perfect entireness. In the amber of Prussia eight hundred different kinds of insects have been determined, most of them belonging to species, and even genera, that appear to be distinct from any now known; while of the others, some are nearly related to indigenous species, and some seem identical with existing forms that inhabit the warmer climates of the south. From their great specific variety and abundance we may infer that insects then, as now, formed the most numerous division of the animal kingdom. Our entomologists reckon at the present time about eleven thousand species of recent British insects, — a number many times greater than that of all its other denizens of the animal kingdom united. You will scarce deem the riddle regarding the entombment of these fragile creatures in the amber, which so puzzled the poet, particularly a hard one : the process must have resembled that which we see going on in our pine-forests every summer. The little flutterers must have settled on the bleeding trunks of the Pinus succinifer, and stuck fast, and the after flow of the sap covered them over. They add an interesting feature, [095]  identical with that sung by the poet, to the odoriferous amber forests of the Tertiary. The hot sun is riding high over the recesses of one of these deep woods, never yet trodden by human foot, and lighting up the waved lines of delicate green with which spring, just passing into early summer, has befringed the dark pines, and the yet unwithered catkins of the poplar and plane, and the white blossoms of the buckthorn. The cave-bear and hyena repose in silence in their dens, and not a wandering breeze rustles among the young leafage.
But hark ! how through the peopled air
    The busy murmur glows;
The insect youth are on the wing,
Eager to taste the honeyed spring,
And float amid the liquid noon:
Some lightly o'er the current skim,
Some show their gaily gilded trim
    Quick glaring to the sun.'
And lo ! where the forest glade terminates in a brown primeval wilderness, the sunbeams fall with dazzling brightness on the trunk of a tall stately tree, just a little touched with decay; and it reflects the light far and wide, and gleams in strong contrast with the gloom of the bosky recesses beyond, like the pillar of fire in the wilderness relieved against the cloud of night. 'Tis a decaying pine of stateliest size, bleeding amber. The insects of the hour flutter around, it; and when, beguiled by the grateful perfume, they touch its deceitful surface, they fare as the lords of creation did in a long posterior age, in that
        'Serbonian bog,
Betwixt Damiata and Mount Casius old,
Where armies whole have sunk.'
But, as happened to so many of the heroes of classic history, death is fame here, and by dying they became immortal; for it is from the individuals who thus perish that future [096] ages are yet to learn that the species which they represent ever existed, or to become acquainted with even the generic peculiarities by which they were distinguished.

The question still remains, Whence has the amber of our Scottish coasts been derived? It occurs in situ in Tertiary deposits in the neighbourhood of London: good specimens of considerable size have been found, for instance, in a clay-pit near Hyde Park corner, not a quarter of a mile fiom the site of the Crystal Palace. It occurs, too, in Prussia, in a clay-bed of considerable horizontal extent, of which the larger part lies under the waves of the Baltic, but which rises on some parts of the coast about forty feet over the level of that sea, and to which of late years a sort of classical interest has been given by a modern fiction, worthy, from its air of matter-of-fact truthfulness, of our own Defoe, — the Amber Witch. The black amber vein found by the pastor's little daughter is described in the story as occurring high in a wooded defile behind her father's parsonage, and as owing its black colour to the quantity of charcoal, i.e., carbonized wood, which it contained. And in both particulars the description is true to the geology of the amber deposits. But we have no amber deposits in Scotland: had amber ever existed in connexion with the Tertiary beds of Mull, it would have shared, in all probability, from the close proximity of the trap, the fate of the great lumps of butter which that giant in the nursery story who used to eat knights and young ladies, employed in testing the heat of his oven; and so we must look for its place, not on our shores, but in the seas by which they are washed. But it is here necessary that I should submit to you a brief outline of the structural geology of our country, not only that we may know in what direction to look for its Tertiary beds, but in order also that we may form such an acquaintance with the general frame work of our subject, as it exists in space, as may guide us in all our after conceptions regarding it. Avoiding the prolixity [097] of minute detail, I shall present you at present with but a few of the leading lines.

The great central nucleus of Scotland, presenting considerably more than fifteen thousand square miles of surface, consists of what we shall term, with the elder geologists, primary rocks, — granites, gneisses, mica-schists, quartz-rocks, and clay-slates. These extend in one direction from the southern base of the Grampians to the northern limits of Sutherlandshire, and from Peterhead and Aberdeen on the east to Gleneig and Loch Carron on the west. [Now, around this great primary mass there runs a ring of the sedimentary fossiliferous rocks, somewhat, though of course not with such unbroken regularity, as a frame runs round a picture, or as the metallic setting of a Cairngorm or pebble brooch surrounds the stone. Of these earlier fossiliferous rocks, known about the beginning of the present century as the Grauwacke, and now as the Silurians, the frame or ring contains but fragments, — a narrow strip along the flanks of the Grampians on the south, and a few detached patches along the shores of Banff on the north and east. But the ring or frame of the next oldest fossiliferous system, the Old Red Sandstone, is very nearly complete; and to such a breadth do we find it developed, especially in the southern and northern parts of the enclosing frame, that, with the addition of a few patches in the border counties of Scotland, we find it occupying nearly five thousand square miles of the surface of our country.1] Outside the Old


1 The Old Red Sandstone frame, and its corresponding illustrations, no longer hold good. The geology of north-western Scotland has recently been investigated by Sir Roderick Murchison, from whose researches it appears that Silurian strata occupy a much wider area of that district than had been previously suspected. Aided by Mr. Peach's discovery of Lower Silurian fossils in the crystalline limestones of Sutherlandshire, Sir Roderick has succeeded in showing that from the Atlantic to the German Ocean there is a regular succession of strata in ascending order, representing the Laurentian gneiss of Canada and the [098f] Cambrian and Lower Silurian rocks of Wales, and superposed upon these older formations in the great Old Red Sandstone of Caithness. See the abstract of Sir Roderick Murchison's paper in the Reports of the Leeds Meeting of the British Association. — G.

[098] Red Sandstone frame there occurs to the south, in the line of the great flat valley which runs across the country from the Firth of Forth to that of the Clyde, a broad belt of the Coal Measures, — the system which succeeds to it in natural sequence; but on the east, west, and north, the Coal Measures and New Red Sandstone are wanting, and we find fragments of a ring of Lias, as at Applecross on the one coast, and at Cromarty and Shandwick on the other; and outside the Lias, considerable fragments of yet another and wider ring of the Oolite. The sea on the east coast, and both that and numerous outbursts of overlying trap on the west, covers up the ring which lies beyond; but the Chalk flints and Greensand fossils of Aberdeen and Banff shires on the one hand, and the Chalk flints of Mull and Caithness on the other, indicate its existence and its components. An outer ring or fiame of Chalk and Greensand, more or less broken, surrounds on two, mayhap on three, sides, the central nucleus of the kingdom; and were the beds of the German and Atlantic Oceans to be laid dry to the depth of about fifty fathoms, and the area of Scotland to be proportionally extended, you would find formation succeeding formation, in crossing the ring from the nucleus outwards, as we find them succeeding each other in the south of England, when crossing the country from South Wales in the direction of London. Beyond this outer ring of Chalk there lie, it is more than probable, deposits of the Tertiary system. Of the Mull deposits on the west coast we at least know, though they occur in so disturbed and overflown a district, that they lie outside the Secondary deposits of the island; and again on the east coast, where the Tertiary deposits, which occupy so large a portion of [099] the south-eastern portion of England, outside the Chalk, lose themselves in the German Ocean, the dredge has found interesting trace of them far at sea running northwards, to form, apparently, our submarine belt or ring. It is stated by Woodward, in his Geology of Norfolk, that the oyster-fishers on that coast dredged up from a tract of oyster-beds near Happisburgh no fewer than two thousand grinders of mammoths in the course of thirteen years. Further, those parts of the Continent which lie opposite our eastern coasts, including Holland, Hanover, and the larger part of Denmark, all consist of deposits of the Tertiary system, which, trending westwards at a low angle, form, it is probable, no inconsiderable part of the bed of the German Ocean. Those beds, however, from which our Scottish amber is derived must lie deep in the sea, outside the Lias, the Oolite, the Green-sand, and the Chalk; and our specimens are rare in consequence, because at great depths the bottom is little affected by tempests. Not less than eight hundred pounds weight of this substance has been thrown up on the coast of east Prussia by a single storm.

From the Tertiaries we would naturally pass, in our upward progress, to the Secondary deposits; and of these, the remains of the Cretaceous system, as exhibited in Banif and Aberdeen shires, would, of course, first solicit notice, as representative in Scotland of that portion of the Secondary period nearest our own, — the period with which this great middle division of the earth's history terminated. I must first, however, call your attention to a series of rocks which, without belonging to any of the three great sedimentary divisions, seem in our own country to have been contemporary with them all. I refer to the trap rocks of the kingdom. The Duke of Argyll found in the island of Mull, as has been already shown, thick beds of trap, tuffacious and basaltic, overlying beds of the Tertiary division. Again, in the Isle of Skye, Professor Edward [100] Forbes has detected trap beds which made their way to the surface, and overflowed the shells and corals of the Oolite, about the middle of the great Secondary period. 'The thick sheet of imperfectly columnar basalt,' says the Professor, ' which has so wide an extension in the island of Skye, and plays so important a part in the formation of the magnificent scenery of its coasts, was the product of a submarine eruption, which, if we regard the basalt as an overflow, has its geological date marked to a nicety, having occurred at the close of the middle and at the commencement of the upper Oolitic period.' Yet again, in the neighbourhood of Edinburgh, as well described by Mr. Charles M'Laren, there are traps of the Palæozoic division, — beds of stratified tuff; as among the rocks of the Calton Hill, for instance, — that belong to the early part of the Carboniferous period; and I have seen at Oban a conglomerate low in the Old Red Sandstone, formed chiefly of a trap, which even at that early time must have been a surface rock much exposed to denudation. We must regard, then, the trap rocks of Scotland as of all ages, from the earlier Palæozoic to the middle Tertiary periods. The great ganoidal fishes of the Devonian and Carboniferous ages, the huge reptiles of the Oolite, and the gigantic mammals of the Miocene, must have been exposed, in turn, in what is now Scotland, to deluging outbursts of molten matter from the vexed bowels of the earth, and to overwhelming showers of volcanic ashes.

I would, however, crave attention to the curious fact, that during this immensely protracted period of Plutonic activity, the deep-seated agencies operated in nearly the same lines. Masses of the incarcerated matter seem to have made their escape age after age along the same weak parts of their prison walls, — the earth's crust; and in Scotland we have two of those lines of apparent weakness which converge in a greatly overflown district in the north of Ireland. One of [101] these lines runs along the inner Hebrides nearly south and north, and includes in its area, as distinct centres of Plutonic action, the islands of Skye and of Mull, with what are known as the Small Isles lying between, and the promontory of Ardnamurchan. The other line sweeps across the country from north-east to south-west, commencing at Dunbar on the east, and terminating, in Scotland, with Arran and Campbelton on the west; but running, as I have said, across the Irish Sea, it re-appears in Ulster. It includes, among many lesser trap eminences, the Campsie, the Ochil, and the Tomond hills; the eminences also on which the castles of Stirling and Dumbarton are built; the hills which give character to the scenery around Edinburgh, — Corstorphine, Blackford, the Pentlands, the Castle rock, the Calton, Salisbury Crags, and Arthur Seat; and, far to the east, that Haddington group of trap hills to which North Berwick Law, the Bass, and the Isle of May belong. Beyond these great lines of injected cracks and filled-up craters, especially to the north and east, there are wide districts in Scotland in which there does not occur a single trap rock. The lava-like flood found its way to the surface from the fiery depths beneath, through the chinks and crannies which we now find indicated by the dikes and insulated stacks and hills of what we may term the Lothian and Hebridean lines, and through these only; and those portions of the Lowlands of Scotland which lie to the north of the Grampians, such as the plains of Caithness, Moray, and Easter Ross, present, from the absence of the trap, an entirely different character from that exhibited by the Lowlands of the south.

The igneous rocks have been divided, according to their mineral or mechanical character, into tuffs, amygdaloids, porphyries, dolerites, claystones, clinkstones, wackes, trachytes, and various other species. For our present purpose, however, and as adequate to the demands of our necessarily brief and imperfect sketch, we may regard the trap rocks [102] as consisting of but two great divisions, — first, the traps proper, including all igneous masses, from the porphyries to the basalts, which were ejected from the abyss in a molten form, and which either overflowed from their vents and craters certain portions of the earth's surface, whether sub-aqueous or subaerial, or, forcing their way between strata of the sedimentary rocks, formed among them dykes, or beds, or pillar-like masses; and secondly, trap-tuffs, which, though igneous in their components, were ejected from craters in the form of loose ashes and detached fragments, or were ground down by the agency of water, and subsequently arranged in regular strata under the same laws which have given their stratification to the rocks of aqueous origin amid which we so frequently find these trap-tuffs intercalated. You will at once see that the division here is a natural one. There is a wide difference betwixt a stratum of broken glass and scoriæ, the débris of a glass-house arranged by the tide on the beach on which it had been cast down a few hours before, and a continuous sheet of plate-glass still retaining its place in the mould into which it had been run off by sluices from the furnace. And such is the difference between trap-tuff and trap proper. We have to arrive, too, when we find them occurring, as in this neighbourhood, among the rocks of a district, at very different conclusions regarding their date and history. Without inquiring whether in some rare instances an eruption of volcanic mud might not possibly be ejected, by a sort of hydraulic-press process, between strata of previously existing rock, and thus a tuff-bed come to be formed which was not only newer than the stratum on which it rested, but also than that by which it was overlaid, we may receive it as a general fact, that the true tuff-bed, like beds of the ordinary sedimentary rocks, is more modern than the stratum on which it rests, and more ancient than the stratum which overlies it; that if it occur, for instance, [103] among the Old Red Sandstones, it belongs to the age of the Old Red Sandstones; if among the Coal Measures, to the age of the Coal Measures; and if among the Oolites, to the age of the Oolites. But we cannot predicate after the same fashion, that the bed of trap proper which we find resting over one series of sedimentary strata and under another is of nearly the same age as the rock above and below, or just a little older than the upper and a little newer than the nether ones. It may have been injected among them many ages after their deposition, during even an entirely different period of the earth's history. We may safely infer, that those beds of stratified trap-tuff which alternate in the Calton Hill with beds of trap-porphyry belong to the Carboniferous period, and are very considerably older than the overlying sandstones and shales on which Regent Terrace is built; but we can no more infer that the great bed of greenstone which forms the picturesque crown of Salisbury Crags is of the same age as the rocks among which it occurs, or, more strictly, a little newer than the strata below and a little older than the strata above, than we can infer that a cast-iron wheel or axle is of the same age as the mould into which it was run, or, more strictly, a little newer than the bottom of the mould, and a little older than the top of it.1

Let us now devote a brief space to the consideration of


1 The usual test of the age of these melted traps is the relation they bear to the rocks which overlie them. If the part of the superjacent bed resting on the igneous rock present an altered appearance, as if it had been more or less baked in a furnace, the trap is regarded as intrusive, that is, it forced its way between the planes of the strata, and must consequently be of later age. If, on the other hand, the beds above display no symptom of alteration, and more especially if they consist of trap-tuff, the underlying igneous rock may be presumed to have been erupted either under water or in open air, as the case may be; and hence it is regarded as in a general way contemporaneous with the strata among which it occurs. — G.

[104] the scenery usually associated with the trap rocks, — a subject which should possess some little interest to an Edinburgh audience, seeing that their most magnificent of cities owes almost all that is imposing and peculiar in its aspect and appearance to this cause. The scenery of a trap district may be resolved into two components. In an ancient ruin we frequently see stones hollowed by decay into a sort of fantastic fretwork, not very unlike that which roughens some of our more ancient runic obelisks; and we recognise as the cause of these irregularities of surface on which the effect depends, certain original inequalities in the texture of the mass, and certain weathering influences, which, while they wore away the softer portions, spared such as were harder and more durable. And such, on a larger scale, are the two elements operative in the production of the pecu liarities of trap scenery. The hard trap rocks injected into the comparatively soft sandstones and shales of a district, such as that which surrounds the Scottish capital, compose a mass of very various texture and solidity, which, if operated upon equally by some power analogous to the weathering one in the case of the fretted stone, would necessarily yield unequally; and the weathering influences we find represented on the large scale by the denuding agencies. The noble eminences which give character and individuality to our city were literally scooped out of the general mass by tides, and waves, and deep-acting currents, as the sculptor chisels out his figures, in executing some piece in alto relievo, by chipping away the surrounding plane. The bold figure of the poet Hogg becomes almost a literality here

'Who was it scooped these stony waves?
Who scalped the brows of old Cairngorm,
And dug these ever-yawning caves?
'Twas I, the Spirit of the Storm.'
The masses of enclosed trap are of various forms. Some times they occur as deeply-based pillar-like masses, filling up, [105] it is possible, ancient craters. The rock of hard clinkstone on which the Castle of Edinburgh stands is one of these; but the long inclined plane of sedimentary deposits which it shielded from the wear of the western current interferes with its column-like outline. The Bass Rock is an example of the same kind, with no sedimentary tail to mar the effect of its natural outline. The dike is another and yet more characteristic form of trap rock: it is a rock that was moulded in a longitudinal crack or rent, as the other was moulded in a well-like crater; and when the original matrix in which it was cast has been washed from its sides, and it remains standing up over the level, it assumes the wall-like or dike-like form to which it owes its name. In sailing along the west coast of Scotland in a clear sunny day, that gives to each projecting crag its deep patch of shadow, these fragments of walls, of vastly more ancient date than the oldest and most venerable of our Scottish ruins, may be seen rising from the beach along the faces of grassy banks or rounded tuff-formed precipices, and communicating to the general scenery one of its most characteristic features. But one of the main scenic peculiarities of the trap districts is derivable from their trap beds. We find in this neighbourhood, among the hills of the Queen's Park, bed rolled over bed, with bands of shale, or sandstone, or soft trap-tuff, between; and these beds, ranged often in nearly parallel lines, and bared by the denuding agencies, present not unfrequently, seen in profile, the appearance of a flight of steps. Hence the generic name for this class of rocks, — trappa, a stair: the traps are the stair-like rocks. As seen in a calm, clear morning, from nearly the eastern termination of Regent Terrace, the Arthur Seat group of hills exhibits three of these beds ranged for considerable distances in nearly parallel lines, and, with these, well-marked fragments of several others. First, reckoning from the west or south, there is the continuous greenstone bed of Salisbury Crags; next, the [106] partially-broken bed of greenstone porphyry known as the Bay Crag; next, the continuous bed of compact greenstone known as the Hill Crag, — that along the top of which the path ascends to the summit of Arthur Seat from St. Anthony's Well; and then there are at least two beds of basalt, partially sanded over, which rise in interrupted steps along the face of the eastern hill. These beds form the peculiar feature of the fine fragment of landscape which from this point of view the Arthur Seat group of hills composes.1 The trap scenery may be described generally as eminently picturesque. From the circumstance that its eruptive masses rise often from amid level fields, and that its hard abrupt beds, dikes, and columns, alternate often with rich, soft strata, that decompose into fertile soils, it abounds in striking contrasts. The soft plain ascends often at one stride into a hill fantastically rugged and abrupt; and bare and fractured precipices overtop terraced slopes or level platforms, rich in verdure. Some of the more famed scenery of England owes its peculiar beauty to the trap rocks. Hagley, the seat of the Lytteltons, so celebrated in the English poetry of the last century for its beauty, is situated half on a range of picturesque trap hills, half on a level plain of the New Red Sandstone; and the far-famed view from the Leasowes owes much of its beauty to the traps of the Clent Hills. But it would be unpardonable, in treating, however slightly, of the scenery of the trap, to omit all reference to one of its strangest features,  — those ranges of polygonal columns which, in at least the more perfect specimens, are peculiar to it, and which impart to Dame Nature, in so many instances, those qualities of proportion and regularity in which art can alone

1 On the west coast of Mull, and the islands of Gometra and Ulva six or eight of these step-like beds may be seen, rising the one over the other, like terraces or storeys in a building; and the whole landscape seems barred with right lines, that in this district lie nearly parallel to the horizon.

[107] pretend to vie with or surpass her. The specimens in our own neighbourhood are either of small extent, as in Samson's Ribs, or both that and of imperfect form, as at St. Anthony's Chapel and in the adjacent hill front; but I have seen in the neighbourhood of Linlithgow a range of slender columns sufficiently regular to have given rise to a traditional myth in the locality, that they owe their origin to the ingenuity of the old Picts; and the columned scuir of Eigg greatly surpasses in grandeur the far-famed Giants' Causeway, and scarce falls short of it in the symmetry of its strange architecture. To that wondrous ocean cave of the west which an enlightened age continues to recognise as one of the marvels of Scotland, I need but refer in the graphic verse which the Ettrick Shepherd has transferred, in his Queen's Wake, to 'Allan Bawn, the Bard of Mull :' —

'Awed to deep silence, they tread the strand,
Where furnaced pillars in order stand;
All framed of the liquid burning levin,
And bent like the bow that spans the heaven;
Or upright ranged, in wondrous array,
With purple of green o'er the darkness grey.
The solemn rows in that ocean den
Were dimly seen like the forms of men ;
Like giant monks in ages agone,
Whom the god of the ocean had sear'd to stone;
And their path was on wondrous pavement old,
In blocks all cast in some giant mould.'
The old scenery of the trap rocks of Scotland, — the scenery associated with them when our country, along at least its two great lines of trappean eruption, was a Tierra del Fuego, — a land of fire, — it would require some of that poetic faculty to restore which I would fain challenge for the geologist. Even in the immediate neighbourhood of the capital, the rocky crust of the earth has been heaved into vast waves by the imprisoned Plutonic agencies struggling for vent; huge floods of molten matter, now hardened into mountain masses, [108] have been injected with earthquake throes between the folds of the stony strata; and a submarine volcano has darkened the heavens with its ashes, shutting out during the day the light of the sun, and throwing its red gleam, when the night had fallen, over the steaming eddies of a boiling and broken sea. The area which we now occupy has heaved like the deck of a storm-beset vessel; the solid earth has been rent asunder; and through the wide cracks and fissures, now existing as greenstone dikes, the red molten matter has come rushing through. Could we this evening ascend into the remote past, when that picturesque eminence which over looks Edinburgh, — according to the poet Malcolm,
        'Arthur's craggy bulk,
That dweller of the air, abrupt and lone, ' —

was, like the son of Semele, first ushered into the world amid smoke and flame, you would find the scene such as poets might well desire to contemplate, or solicit the aid of their muse adequately to describe. For many ages, what now exists as the picturesque tract of hill and valley attached to old Holyrood, and to which the privileges of the court still extend, had existed as a tract of shallow sea, darkened, when the tide fell, by algæ-covered rocks and banks, and much beaten by waves. From time immemorial has the portion of the earth's crust which underlies that shallow sea been a scene of deep-seated igneous action. Vast beds of trappean rock, — greenstone, and columnar basalt, and amygdaloidal porphyry, — have been wedged from beneath, as molten injections, between the old sedimentary strata; vast waves of translation have come rolling outwards from that disturbed centre, as some submarine hill, elevated by the force of the fiery injection — as the platform of a hydraulic press is elevated when the pump is plied — has raised its broad back over the tide, only, however, to yield piecemeal to the denuding currents and the storm-raised surf of centuries. And [109] for day after day has there been a succession of earthquake shocks, that, as the Plutonic paroxysm increases in intensity, become stronger and more frequent, and the mountain-waves roll outwards in ever-widening circles, to rise and fall in distant and solitary seas, or to break in long lines of foam on nameless islands unknown to the geographer. And over the roar of waves or the rush of tides we may hear the growlings of a subterranean thunder, that now dies away in low deep mutterings, and now, ere some fresh earthquake-shock tern- pests the sea, bellows wildly from the abyss. The billows fall back in boiling eddies; the solid strata are upheaved into a flat dome, crusted with corals and shells; it cracks, it severs, a dark gulf yawns suddenly in the midst; a dense strongly variegated cloud of mingled smoke and steam arises black as midnight in its central volumes, but chequered, where the boiling waves hiss at its edge, with wreaths of white; and anon, with the noise of many waters, a broad sheet of flame rushes upwards a thousand fathoms into the sky. Vast masses of molten rock, that glow red amid even the light of day, are hurled into the air, rind then, with hol low sound, fall back into the chasm, or, descending hissing amid the vexed waters, fling high the hot spray, and send the cross circlets of wave which they raise athwart the heavings of the huger billows propelled from the disturbed centre within. The crater rises as the thick showers of ashes descend; and amid the rending of rocks, the roaring of flames, the dashings of waves, the hissings of submerged lava, and the hollow grumblings of the abyss, the darkness of a starless night descends upon the deep. Anon, and we are startled by the shock of yet another and more terrible earthquake; yet another column of flame rushes into the sky, casting a lurid illumination on the thick rolling reek and the pitchy heavings of the wave: seen but for a moment, we may mark the silvery glitter of scales, for there is a shoal of dead fish floating past; and as the coruscations [110] of an electric lightning darts in a thousand fiery tongues from the cloud, some startled monster of the deep bellows in terror from the dank sea beyond.

Let us raise the curtain once more from over the past of the trap districts of Scotland. Myriads of ages have come and gone; the submarine volcano has been long extinguished; and the land, elevated high over the waters, has become a scene of human habitation. But the wild country, marked by the well-known features of abrupt precipitous hill and deep retiring valley, is roughened by many a shaggy wood, and gleams with many a blue lochan, and even its richer plains are but partially broken up by the plough. And lo! the trappean centres of the district are scenes of fierce war, as of old; but it is not the dead uninformed elements, — fire, earth, and water, — but energetic, impassioned man, that now contends, and in fierce warfare battles, with his kind. Yonder, on its trap rock, once the crater of a volcano, is the fortress of the Bass, the stronghold that last surrendered in Britain to William of Nassau; and yonder, on its trap rock, the castle of Dunbar, that brave black Agnes held out in so determined a spirit against the English; and yonder, on its trap rock, the castle of Dirleton, which stood siege in behalf of our country against Edward I.; and yonder, on its trap rock, scaled by Lord Randolph of old when he warred for the Bruce, is the castle of Edinburgh, the scene of a hundred fights, and surrrounded by the halo of a thousand historic associations; and yonder, on its trap rock, is the castle of Stirling, with the battle ground of Scotland at its feet, and to maintain which against the greatest of our Scottish kings, the second Edward vainly fought the battle of Bannockburn; and yonder, on its trap rock, is the castle of Dumbarton, long impregnable, but which the soldier of the Reformation won at such fearful risk from the partisans of Mary. I remember at one time deeming it not a little curious that the early [111] geological history of a country should often, as in this instance, seem typical of its subsequent civil history. If a country's geologic history had been much disturbed, — if the trap rock had broken out from below, and tilted up its strata in a thousand abrupt angles, steep precipices, and yawning chasms, I found the chances as ten to one that there succeeded, when man came upon the scene, a history, scarce less disturbed, of fierce wars, protracted sieges, and desperate battles. The stormy morning during which merely the angry elements had contended, I found succeeded in almost every instance by a stormy day maddened by the turmoil of human passion. But a little reflection dissipated the mystery; though it served to show through what immense periods mere physical causes may continue to operate with moral effect, and how, in the purposes of Him who saw the end from the beginning, a scene of fiery confusion, — of roaring waves and heaving earthquakes, of ascending hills and deepening valleys, — may have been closely associated with the right development and ultimate dignity and happiness of the moral agent of creation, — unborn at the time, — reasoning, responsible man. It is amid these cehtres of geologic disturbance, the natural strongholds of the earth, that the true battles of the race, the battles of civilisation and civil liberty, have been successfully maintained by handfuls of hardy men, against the despot-led myriads of the plains. In glancing over a map of Europe and the countries adjacent, on which the mountain groups are marked, you will at once perceive that Greece and the Holy Land, Scotland and the Swiss cantons, formed centres of great plutonic disturbance of this character. They had each their geologic tremors and perturbations, — their protracted periods of eruption and earthquake, — long ere their analogous civil history, with its ages of convulsion and revolution, in which man was the agent, had yet commenced its course. And, indirectly at least, the disturbed civil history was [112] in each instance a consequence of the disturbed geologic one.
From the Tertiary deposits we pass direct to the few scattered remains which survive in Scotland of the Cretaceous period. It is now nearly thirty years since it was found by geologists that chalk flints, enclosing in many specimens the peculiar organisms of the system, occur in the superficial deposits of Banff and Aberdeenshires; and about three years ago they were also discovered by a very ingenious man, a Thurso tradesman, Mr. Robert Dick, in the boulder-clays of Caithness. It is, however, a curious fact, that what the geologist has only come to know within the course of the present generation was well known to the wild aboriginal inhabitants of the country some three or four thousand years ago. Well-nigh one half the ancient arrow and smaller javelin heads of the stone period in Scotland, especially those found to the north of the Grampians, were fashioned out of the yellow Aberdeenshire flints. A history of those arts of savage life which the course of discovery served to supplant and obliterate, but which could not be carried on without a knowledge of substances and qualities afterwards lost, until re-discovered by scientific curiosity, would form an exceedingly curious one. On finding, a good many years ago, a vein of a bituminous jet in one of the ichthyolite beds of the Old Red Sandstone of Ross, — beds unknown at the time to even our first geologists, — it curiously impressed me to remember that my discovery was, after all, only a discovery at second-hand; for that in an unglazed hand-made urn of apparently a very early period, dug up in the neighbourhood only a few years before, there had been found a very primitive necklace, fashioned out of evidently the same jet. It would seem that to these ichthyolite beds, unknown at the time in the district to all but myself; the savage inhabitants had had recourse for the materials of their rude ornaments thousands of years before.

[113] They were mineralogists enough, too, as their stone hatchets and battle-axes testify, to know where the best tool-and-weapon-making rocks occur; and I once found in a northern locality a battle-axe of an exceeding strong and tough variety of indurated talc, that nearly approached in character to the axe-stone of Werner, which, if native to Scotland at all, is so in some primary district which I am not mineralogist enough to indicate. It shows us after how strange a fashion extremes may meet, — that rude savages, ignorant of the use of the metals, and the scientific explorers of a highly civilized age, rationally desirous to know how the adorable Creator wrought upon this earth of old, ere man had yet entered upon it as a scene of probation, should have formed an acquaintance with the same classes of objects, — classes of objects of which the men of an intervening period knew nothing.

The chalk fragments and flints of Caithness and Banif seem to have been carried eastwards on the occidental current of the Pleistocene period, — those of the one county from that western portion of the chalk ring or girdle to which I have already referred as lying in the Atlantic, and those of the other from that eastern portion of the ring which is buried in the outer reaches of the Moray Firth. In Aberdeenshire, however, some twenty miles or so to the north of the city, in the parish of Ellon and some of the contiguous parishes, and running at a considerable distance inland in a line nearly parallel to the coast, the flints so abound, and, unlike those of the English gravels, are so little water-worn, as to give evidence that they must have been derived from the disintegration of outliers of the system that once existed, it is probable, in their immediate neighbourhood. They overlie, too, in some parts of this locality, what seems to be a re-formation of the greensand; of which the soft incoherent masses, containing, as they do, in some instances in a good state of keeping, some of the more [114] fragile organisms of the deposit, could not possibly have travelled far. The fossils of our chalk flints and of the underlying greensand are sufficiently numerous and characteristic to serve the purpose of identifying the worn and scattered deposits in which they occur with the amply developed chalks and greensands of England, but perhaps not sufficiently so, nor yet always in a sufficiently fine state of preservation, to render the district a very hopeful scene of labour to the collector desirous absolutely to extend our know ledge of the extinct forms of life. I have seen, however, especially in the collections of Dr. Fleming, the Rev. Mr. Long-muir of Aberdeen, and Mr. Fergusson of Glasgow, fine and very characteristic specimens of the Scotch Chalk, — delicate flustra sponges and corals locked up in flint, — well-marked portions of the sea-egg order (Echinidæ) belonging to the cidarite, galerite, and spatangus families, — terebratulæ of various species, — good specimens of that very characteristic conchifer of the Chalk, the Inoceramus, — with casts of minute belemnites and portions of ammonites and baculites. The group of remains preserved is unequivocally that of the Cretaceous fauna, just as Scotland has also a group of archæological remains decidedly Roman; though in either case these remains serve but for purposes of identification with larger groups elsewhere; and in order thoroughly to study either the one or the other, the antiquary or geologist would have to remove from what is equally the outskirts of the old Roman or old Cretaceous empire, towards its centre in the south.

All our geologists agree in holding that the Chalk was deposited in an ocean of very considerable depth, and of such extent that it must have covered for many ages the greater part of what is now southern and central Europe. It has been traced in one direction from the north of Ireland to the Crimea in Southern Russia, a distance of about twelve hundred miles, and in another direction from the [115] south of Sweden to the south-west of France, a distance of about nine hundred miles; and there are extensive districts both in France and England where it attains to an average thickness of not less than a thousand feet. The only analogous deposit of the present time occurs on comparatively a small scale among the coralline reefs and lagoons of the Pacific, where there is in the act of forming an impalpable white mud derived from the corals, which in dried specimens cannot be distinguished by the unassisted eye from masses of soft chalk. But what chiefly distinguishes the true chalk from any of its modern representatives is the amazing number of microscopic animals which it contains. On a low estimate half its entire bulk is composed of animalculites of such amazing minuteness, that it has been calculated by Ehrenberg that each cubic inch of chalk may contain upwards of a million of the shells of these creatures. The chalk rocks so characteristic of the sister kingdom have been often sung by the poets as

'Rising like white ramparts all along
The blue sea's border.'
And, in especial, one 'chalky bourn of dread and dizzy summit' has been made by the greatest of poets the subject of the sublimest description of a giddy, awe-inspiring precipice ever drawn. And here is there a new association with which to connect the chalk cliffs of England. Every fragment of these cliffs was once associated with animal life; that impalpable white dust which gives a milky hue to the waves as they dash against them, consists of curiously organized skeletons; even the white line which I draw along the board, were our eyes to be suddenly endowed with a high microscopic power, would resemble part of the wall of a grotto covered over with shells. And, embedded in this mass of minute, nicely-framed invisibilities, — Polythalamia, Foraminifera, Polyporia, and Diatomaceæ, — we find fossils of larger size, such as Spatangus-cor and the [116] spiny Plagiostoma, which seem to have found proper habitats in the mud formed by the dead remains of these animalculæ. Curious examples of a similar kind may be still seen among the Hebrides, of sand-burrowing molluscs and echinoderms finding habitats amid accumulations of the debris of organic life, chiefly comminuted shells, on coasts where otherwise there could have been no place for them. The deep-sea shells propelled shorewards by the agency of tides and waves are ground down by the action of the surf against the rocks. They may be seen occurring in the hollows of the skerries, as one passes shorewards along some of the rocky bays, in handfuls of more and more comminuted fragments, just as, in passing along the successive vats of a paper-mill, one finds the linen rags more and more disintegrated by the cylinders ; and then, within some sheltering shelf or ledge, we find the gathered handfuls of former ages spreading into a wave-rippled beach of minute shelly particles, that presents, save in its snow-white colour, the appearance of sandy beaches of the ordinary mineral components. But the beach once formed in this way soon begins to receive accessions from the exuviæ of animals that love such localities, — spatangi, razor-fish, cockles, and the several varieties of the gaper family, — and that enjoy life agreeably to their natures and constitutions, not in the least saddened by the idea that they are living amid the rubbish of a charnel-house; and sometimes one-half the whole beach comes thus to be composed of a class of remains that, save for the previous existence of the other half of it, could not have been formed in such localities at all. Now, such must have been the state of matters in the times of the Chalk. Unnumbered millions must have died in order that the medium might be provided in which a class of their successors could alone live. Of the land which skirted this ocean of the Chalk, or of its productions, we know almost nothing. There have been found in Chalk [117] flints a few fragments of silicified wood, and, in one or two instances, the cones of cycadaceous plants; and the upper beds of the system have furnished the remains of a gigantic lizard, — the Mosasaurus, with those of turtles, tortoises, and Pterodactyls. True, the Mosasaurus may have been, as Cuvier supposed, a marine reptile, and the turtles must have been so; but then both, as egg-bearing animals, must have brought forth their young on some shore; and the tortoises, with the Pterodactyl or flying lizard, must be regarded as decidedly terrestrial. Such is almost all we yet know of the flora or fauna of the land of the Chalk; whereas in marine organisms the system is so exceedingly rich, that its ascertained species amount, we find it stated by Brown, to about three thousand. The geologic diorama abounds in strange contrasts. When the curtain last rose upon our country, we looked abroad over the amber-producing forests of the Tertiary period, with their sunlit glades and brown and bosky recesses, and we saw, far distant on the skirts of the densely wooded land, a fire-belching volcano, over-canopied by its cloud of smoke and ashes. And now, when the curtain again rises, we see the same tract occupied, far as the eye can reach, by a broad ocean, traversed by a pale milky line, that wends its dimpling way through the blue expanse, like a river through a meadow. That milky way of turbid water indicates the course of a deep-setting current, that disturbs, far beneath, the impalpable mud of the Chalk. Sailing molluscs career in their galleys of pearl over the surface of this ancient sea ; fishes of long extinct species dart with sudden gleam through its middle depths; and far below, on its white floor, the sea-urchin creeps, and the spatangus burrows, and crania and terebratuke have cast anchor, and the &is/a Galli (or carinated oyster) opens its curiously plicated valves, carved with the zigzag mouldings of a Norman doorway, and the flower-like marsupite expands its living petals. And, dim and distant in the [118] direction of the future Grampians, we may espy a cloud-enveloped island; but such is its remoteness, and such the enveloping haze, that we can know little more than that it bears along its shores and on its middle heights a forest of nameless trees, unchronicled by the fossil botanist.

In bringing to a close this part of my subject, let me here remark that, if we except the obscure and humbly organized diatomaceæ, — a microscopic family of organisms which some of our authorities deem animal and some vegetable, and of which hundreds and thousands would find ample room in a single drop of water, — we have now reached a point in the history of our country in which there existed no species of plant or animal that exists at the present time. Not a reptile, fish, mollusc, or zoophyte of the Cretaceous system continues to live. We know that it is appointed for all individuals once to die, whatever their tribe or family, because hitherto all individuals have died; and Geology, by extending our experience, shows us that the same fate awaits on species as on the individuals that compose them. In the one case, too, as in the other, death has its special laws; but the laws which determine the life and death of species seem widely different from those which regulate the life and death of individuals and generations. In general, and with but a few exceptions in favour of the cold-blooded division of the vertebrata, the higher orders of animals live longest. A man may survive for a hundred years; an ephemera bursts from its shell in the morning, and dies at night. But it is far otherwise with the higher orders of species. Molluscs and corals outlive the vertebrata; and tribes of the low infusory animals outlive molluscs and corals. We know not that a single shell of at least the latter Pleistocene period has become extinct; but many of its noblest quadrupeds, such as the Irish elk, the cave-bear, tiger, and hyena, and the northern rhinoceros, hippopotamus, and elephant, exist no longer. And as we [119] rise into the remote past, and take farewell, one after one, of even the lower forms, — shells and corals, — and get into a formation all of whose visible organisms are old-fashioned and extinct, we apply the microscope to its impalpable dust, and again, among still humbler and lowlier shapes, find ourselves in the presence of the familiar and the recent. In another sense than that which the old poet contemplated, we learn from the history of species that the most lowly are the most safe.

'The tallest pines feel most the power
Of wintry bhists ; the loftiest tower
Comes heaviest to the ground.
The bolts that spare the mountain side
His cloud-capt eminence divide,
And spread the ruin round.'
How long some of these extinct species may have lived we know not, and may never know; but in all cases their term of existence must have been very extended. Even the extinct elephant lived long enough as a species to whiten the plains of Siberia with huge bones, and to form quarries of ivory that have furnished the ivory market for year after year with its largest supplies. And of some of the humbler species of animals the period during which they have continued to live must have been vastly more protracted. Cyprina Islandica seems to have come into existence at least as early as the fossil elephant; and now, thousands of years after the boreal pachyderm is gone, the boreal shell still exists by millions, and evinces no symptom of decline. And yet, since the commencement of the great Tertiary division, series of shells, as hardy, apparently, as Cyprina, have in succession come into being, and then ceased to be. The period over which we have passed in cludes generations of species. But there was space enough for them all in the bygone eternity. It has sometimes appeared to me as if, from our own weak inability to conceive [120] of the upper reaches of that awful tide of continuity which had no beginning, and of which the measured shreds and fragments constitute time, we had become jealous lest even God himself should have wrought in it during other than a brief and limited space, with which our small faculties could easily grapple.
'Oh, who can strive
To comprehend the vast, the awful truth
Of the eternity that hath gone by,
And not recoil from the dismaying sense
Of human impotence! The life of man
Is summed in birthdays and in sepulchre;
But the eternal God had no beginning.'
There are two great infinites, — the infinite in space and the infinite in time. It were well, surely, to be humble enough to acknowledge it accordant to all analogy, that as He who inhabits eternity has filled the one limitless void — that of space — with world upon world and system upon system, far beyond the reach of human ken, He should also have wrought in the other limitless world — that of time — for age after age, and period after period, far beyond the reach of human conception.