The Cruise of the Betsey Part 8

In a few days the storm blew by; and as the prolonged rains had cleared out the deep ravines of the district, and given to the boulder-clay in which they are scooped a freshness in its section a.n.a.logous to fresh fracture in rocks of harder consistency, I availed myself of the facilities afforded me in consequence, for exploring it once more. It has long const.i.tuted one of the hardest of the many riddles with which our Scottish deposits exercise the patience and ingenuity of the geologist. I remember a time when, after pa.s.sing a day under its barren _scaurs_, or hid in its precipitous ravines, I used to feel in the evening as if I had been travelling under the cloud of night, and had seen nothing. It was a morose and taciturn companion, and had no speculation in it. I might stand in front of its curved precipices, red, yellow or gray, according to the prevailing average color of the rocks on which it rests, and mark their water-rolled boulders, of all qualities and sizes, sticking out in bold relief from the surface, like the rock-like protuberances that roughen the rustic bas.e.m.e.nts of the architect, from the line of the wall; but I had no _open sesame_ to form vistas through them into the recesses of the past. I saw merely the stiff pastry matrix of which they are composed, and the inclosed pebbles. But the boulder-clay has of late become more sociable; and, though with much hesitancy and irresolution, like old Mr. Spectator on the first formal opening of his mouth,--a consequence, doubtless, in both cases of previous habits of silence long indulged,--it begins to tell its story. And a most curious story it is.

The morning was clear, but just a little chill; and a soft covering of snow, that had fallen during the storm on the flat summit of Ben-Wevis, and showed its extreme tenuity by the paleness of its tint of watery blue, was still distinctly visible at the distance of full twenty miles.

The sun, low in the sky,--for the hour was early,--cast its slant rays athwart the prospect, giving to each nearer bank and hillock, and to the more distant protuberances on the mountain-sides, those well-defined accompaniments of shadow that serve by throwing the minor features of a landscape upon the eye in bold relief, to impart to it an air of higher finish and more careful filling up than it ever bears under a more vertical light. I took the road which, leading westward from the town towards Invergordon Ferry, skirts the Frith on the one hand, and runs immediately under the n.o.ble escarpment of green bank formed by the old coast line on the other. Fully two-thirds of the entire height of the rampart here, which rises in all about a hundred feet over the sea-level, is formed of the boulder-clay; and I am acquainted with no locality in which the deposit presents more strongly, for at least the first half mile, one of its marked scenic peculiarities. It is furrowed vertically on the slope, as if by enormous flutings in the more antique Doric style; and the ridges by which these are separated,--each from a hundred to a hundred and fifty feet in length, and from five-and-twenty to thirty feet in average height,--resemble those burial mounds with which the s.e.xton frets the churchyard turf; with this difference, however, that they seem the burial mounds of giants, tall and bulky as those that of old warred against the G.o.ds. They are striking enough to have caught the eye of the children of the place, and are known among them as the Giants' Graves. I could fain have taken their portrait in a calotype this morning, as they lay against the green bank,--their feet to the sh.o.r.e, and their heads on the top of the escarpment,--like patients on a reclining bed, and strongly marked, each by its broad bar of yellow light and of dark shadow, like the ebon and ivory b.u.t.tresses of the poet. This little vignette, I would have said to the landscape painter, represents the boulder-clay, after its precipitous banks--worn down, by the frosts and rains of centuries, into parallel runnels, that gradually widened into these hollow grooves--had sunk into the angle of inclination at which the disintegrating agents ceased to operate, and the green sward covered all up. You must be studying these peculiarities of aspect more than ever you studied them before. There is a time coming when the connoisseur will as rigidly demand the specific character of the various geologic rocks and deposits in your hills, _scaurs_, and precipices, as he now demands specific character in your shrubs and trees.

It is worthy the notice of the young geologist, who has just set himself to study the various effects produced on the surface of a country by the deposits which lie under it, that for about a quarter of a mile or so, the base of the escarpment here is bordered by a line of bogs, that bear in the driest weather their mantling of green. They are fed with a perennial supply of water, by a range of deep-seated springs, that come bursting out from under the boulder-clay; and one of their number, which bears I know not why, the name of Samuel's Well, and yields its equable flow at an equable temperature, summer and winter, into a stone trough by the way-side, is not a little prized by the town's-people, and the seamen that cast anchor in the opposite roadstead, for the lightness and purity of its water. What is specially worthy of notice in the case is, the very definite beginning and ending of the chain of bogs. All is dry at the base of the escarpment, up to the point at which they commence; and then all is equally dry at the point at which they terminate. And of exactly the same extent,--beginning where the bogs begin, and ending where they end,--we may trace an ancient stratum of pure sand,--of considerable thickness, intercalated between the base of the clay and the superior surface of the Old Red Sandstone. It is through this permeable sand that the profoundly seated springs find their way to the surface,--for the clay is impermeable; and where it comes in contact with the rock on either side of the arenaceous stratum, the bogs cease.

The chain of green bogs is a consequence of the stratum of permeable sand. I have in vain sought this ancient layer of sand,--decidedly of the same era with the argillaceous bed which overlies it,--for aught organic. A single sh.e.l.l, so unequivocally of the period of the boulder-clay as to occur at the base of the deposit, would be worth, I have said, whole drawerfuls of fossils furnished by the better-known deposits. But I have since seen in abundance sh.e.l.ls of the boulder-clay.

There is another scenic peculiarity of the clay, which the neighborhood of Cromarty finely ill.u.s.trates, and of which my walk this morning furnished numerous striking instances. The Giants' Graves--to borrow from the children of the place--occur on the steep slopes of the old coast line, or in the sides of ravines, where the clay, as I have said, had once presented a precipitous front, but had been gradually moulded, under the attritive influences of the elements, into series of alternating ridges and furrows, which, when they had flattened into the proper angle, the green sward covered up from further waste. But the deep dells and narrow ravines in which many ranges of these graves occur are themselves peculiarities of the deposit. Wherever the boulder-clay lies thick and continuous, as in the parish of Cromarty, on a sloping table-land, every minute streamlet cuts its way to the solid rock at the bottom, and runs through a deep dell, either softened into beauty by the disintegrating process, or with all its precipices standing up raw and abrupt over the stream. Four of these ravines, known as the "Old Chapel Burn," the "Ladies' Walk," the "Morial's Den," and the "Red Burn," each of them cutting the escarpment of the ancient coast line from top to base, and winding far into the interior, occur in little more than a mile's s.p.a.ce; and they lie still more thickly farther to the west. These dells of the boulder clay, in their lower windings,--for they become shallower and tamer as they ascend, till they terminate in the uplands in mere _drains_, such as a ditcher might excavate at the rate of a s.h.i.+lling or two per yard,--are eminently picturesque. On those gentler slopes where the vegetable mould has had time and s.p.a.ce to acc.u.mulate, we find not a few of the finest and tallest trees of the district. There is a bosky luxuriance in their more sheltered hollows, well known to the schoolboy what time the fern begins to pale its fronds, for their store of hips, sloes, and brambles; and red over the foliage we may see, ever and anon as we wend upwards, the abrupt frontage of some precipitous _scaur_, suited to remind the geologist, from its square form and flat breadth of surface, of the cliffs of the chalk. When viewed from the sea, at the distance of a few miles, these ravines seem to divide the sloping tracts in which they occur into large irregular fields, laid out considerably more in accordance with the principles of the landscape gardener than the stiffly squared rectilinear fields of the agriculturist. They are _ha-has_ of Nature's digging; and their bottom and sides in this part of the country we still find occupied in a few cases--though in many more they have been ravaged by the wasteful axe--by n.o.ble forest-_hedges_, tall enough to overtop, in at least their middle reaches, the tracts of table-land which they divide.

I pa.s.sed, a little farther on, the quarry of Old Red Sandstone, with a huge bank of boulder-clay resting over it, in which I first experienced the evils of hard labor, and first set myself to lessen their weight by becoming an observer of geological phenomena. It had been deserted apparently for many years; and the debris of the clay partially covered up, in a sloping talus, the frontage of rock beneath. Old Red Sandstone and boulder-clay, a broad bar of each!--such was the compound problem which the excavation propounded to me when I first plied the tool in it,--a problem equally dark at the time in both its parts. I have since got on a very little way with the Old Red portion of the task; but alas for the boulder-clay portion of it! A bar of impenetrable shadow has rested long and obstinately over the newer deposit; and I scarce know whether the light which is at length beginning to play on its pebbly front be that of the sun or of a delusive meteor. But courage, patient hearts! the boulder-clay will one day yield up _its_ secret too. Still further on by a few hundred yards, I could have again found use for the calotype, in transferring to paper the likeness of a protuberant picturesque cliff, which, like the Giants' Graves, could have belonged, of all our Scotch deposits, to only the boulder-clay. It stands out, on the steep acclivity of a furze-covered bank, abrupt as a precipice of solid rock, and yet seamed by the rain into numerous divergent channels, with pyramidal peaks between; and, combining the perpendicularity of a true cliff with the water-scooped furrows of a yielding clay, it presents a peculiarity of aspect which strikes, by its grotesqueness, eyes little accustomed to detect the picturesque in landscape. I remember standing to gaze upon it when a mere child; and the fisher children of the neighboring town still tell that "_it has been prophesied_" it will one day fall, "and kill a man and a horse on the road below,"--a legend which shows it must have attracted _their_ notice too.

I selected as the special scene of exploration this morning, a deep ravine of the boulder-clay, which had been recently deepened still more by the waters of a mill-pond, that had burst during a thunder-shower, and, after scooping out for themselves a bed in the clay some twelve or fifteen feet deep, where there had been formerly merely a shallow drain, had then tumbled into the ravine, and bared it to the rock. The sandstones of the district, soft and not very durable, show the scratched and polished surfaces but indifferently well, and, when exposed to the weather, soon lose them; but in the bottom of the runnel by which the ravine is swept I found them exceedingly well marked,--the polish as decided as the soft red stone could receive, and the lines of scratching running in their general bearing due east and west, at nearly right angles with the course of the stream. Wherever the rock had been laid bare during the last few months, _there_ were the markings; wherever it had been laid bare for a few twelvemonths, they were gone. I next marked a circ.u.mstance which has now for several years been attracting my attention, and which I have found an invariable characteristic of the true boulder-clay. Not only do the rocks on which the deposit rests bear the scratched and polished surfaces, but in every instance the fragments of stone which it incloses bear the scratchings also, if from their character capable of receiving and retaining such markings, and neither of too coa.r.s.e a grain nor of too hard a quality.

If of limestone, or of a coherent shale, or of a close, finely-grained sandstone, or of a yielding trap, they are scratched and polished,--invariably on one, most commonly on both their sides; and it is a noticeable circ.u.mstance, that the lines of the scratchings occur, in at least nine cases out of every ten, in the lines of their longer axes. When decidedly oblong or spindle-shaped, the scratchings run lengthwise, preserving in most cases, on the under and upper sides, when both surfaces are scratched, a parallelism singularly exact; whereas, when of a broader form, so that the length and breadth nearly approximate,--though the lines generally find out the longer axis, and run in that direction,--they are less exact in their parallelism, and are occasionally traversed by cross furrows. Of such certain occurrence is this longitudinal lining on the softer and finer-grained pebbles of the boulder-clay, that I have come to regard it as that special characteristic of the deposit on which I can most surely rely for purposes of identification. I am never quite certain of the boulder-clay when I do not detect it, nor doubtful of the true character of the deposit when I do. When examining, for instance, the acc.u.mulation of broken Liasic materials in the neighborhood of Banff, I made it my first care to ascertain whether the bank inclosed fragments of stone or shale bearing the longitudinal markings; and felt satisfied, on finding that it did, that I had discovered the period of its re-formation.

CHAPTER VI.

Organisms of the Boulder-clay not unequivocal--First Impressions of the Boulder-clay--Difficulty of accounting for its barrenness of Remains--Sir Charles Lyell's reasoning--A Fact to the contrary--Human Skull dug from a Clay-bank--The Author's Change of Belief respecting Organic Remains of the Boulder-clay--Sh.e.l.ls from the Clay at Wick--Questions respecting them settled--Conclusions confirmed by Mr. d.i.c.k's Discoveries at Thurso--Sir John Sinclair's Discovery of Boulder-clay Sh.e.l.ls in 1802--Comminution of the Sh.e.l.ls ill.u.s.trated--_Cyprina islandica_--Its Preservation in larger Proportions than those of other Sh.e.l.ls accounted for--Boulder-clays of Scotland reformed during the existing Geological Epoch--Scotland in the Period of the Boulder-clay "merely three detached groups of Islands"--Evidence of the Subsidence of the Land in Scotland--Confirmed by Rev. Mr. c.u.mming's conclusion--High-lying Granite Boulders--Marks of a succeeding elevatory Period--Scandinavia now rising--Autobiography of a Boulder desirable--A Story of the Supernatural.

For the greater part of a quarter of a century I had been finding organisms in abundance in the boulder-clay, but never anything organic that unequivocally belonged to its own period. I had ascertained that it contains in Ross and Cromarty nodules of the Old Red Sandstone, which bear inside, like so many stone coffins, their well laid out skeletons of the dead; but then the markings on their surface told me that when the boulder-clay was in the course of deposition, they had been exactly the same kind of nodules that they are now. In Moray, it incloses, I had found, organisms of the Lias; but _they_ also testify that they present an appearance in no degree more ancient at the present time than they did when first enveloped by the clay. In East and West Lothian too, and in the neighborhood of Edinburgh, I had detected in it occasional organisms of the Mountain Limestone and the Coal Measures; but these, not less surely than its Liasic fossils in Moray, and its Old Red ichthyolites in Cromarty and Ross, belonged to an incalculably more ancient state of things than itself; and--like those shrivelled ma.n.u.scripts of Pompeii or Herculaneum, which, whatever else they may record, cannot be expected to tell aught of the catastrophe that buried them up--they throw no light whatever on the deposit in which they occur. I at length came to regard the boulder-clay--for it is difficult to keep the mind in a purely blank state on any subject on which one thinks a good deal--as representative of a chaotic period of death and darkness, introductory, mayhap, to the existing scene of things.

After, however, I had begun to mark the invariable connection of the clay, as a deposit, with the dressed surfaces on which it rests, and the longitudinal linings of the pebbles and boulders which it incloses, and to a.s.sociate it, in consequence, with an ice-charged sea and the Great Gulf Stream, it seemed to me extremely difficult to a.s.sign a reason why it should be thus barren of remains. Sir Charles Lyell states, in his "Elements," that the "stranding of ice-islands in the bays of Iceland since 1835 has driven away the fish for several successive seasons, and thereby caused a famine among the inhabitants of the country;" and he argues from the fact, "that a sea habitually infested with melting ice, which would chill and freshen the water, might render the same uninhabitable by marine mollusca." But then, on the other hand, it is equally a fact that half a million of seals have been killed in a single season on the meadow-ice a little to the north of Newfoundland, and that many millions of cod, besides other fish, are captured yearly on the sh.o.r.es of that island, though grooved and furrowed by ice-floes almost every spring. Of the seal family it is specially recorded by naturalists, that many of the species "are from choice inhabitants of the margins of the frozen seas towards both poles; and, of course, in localities in which many such animals live, some must occasionally die."

And though the grinding process would certainly have disjointed, and might probably have worn down and partially mutilated, the bones of the amphibious carnivora of the boulder period, it seems not in the least probable, judging from the fragments of loose-grained sandstone and soft shale which it has spared, that it would have wholly destroyed them. So it happened, however, that from North Berwick to the Ord Hill of Caithness, I had never found in the boulder-clay the slightest trace of an organism that could be held to belong to itself; and as it seems natural to build on negative evidence, if very extensive, considerably more than mere negative evidence, whatever the circ.u.mstances, will carry, I became somewhat skeptical regarding the very existence of boulder-fossils,--a skepticism which the worse than doubtful character of several supposed discoveries in the deposit served considerably to strengthen. The clay forms, when cut by a water-course, or a.s.sailed on the coast by some unusually high tide, a perpendicular precipice, which in the course of years slopes into a talus; and as it exhibits in most instances no marks of stratification, the clay of the talus--a mere re-formation of fragments detached by the frosts and rains from the exposed frontage--can rarely be distinguished from that of the original deposit. Now, in these consolidated slopes it is not unusual to find remains, animal and vegetable, of no very remote antiquity. I have seen a human skull dug out of the reclining base of a clay-bank once a precipice, fully six feet from under the surface. It might have been deemed the skull of some long-lived contemporary of Enoch,--one of the accursed race, mayhap,

"Who sinned and died before the avenging flood."

But, alas! the laborer dug a little further, and struck his pickaxe against an old rybat that lay deeper still. There could be no mistaking the character of the champfered edge, that still bore the marks of the tool, nor that of the square perforation for the lock-bolt; and a rising theory, that would have referred the boulder-clay to a period in which the polar ice, set loose by the waters of the Noachian deluge, came floating southwards over the foundered land, straightway stumbled against it, and fell. Both rybat and skull had come from an ancient burying-ground, that occupies a projecting angle of the table-land above. I must now state, however, that my skepticism has thoroughly given way; and that, slowly yielding to the force of positive evidence, I have become as a.s.sured a believer in the _comminuted recent sh.e.l.ls_ of the boulder-clay as in the belemnites of the Oolite and Lias, or the ganoid ichthyolites of the Old Red Sandstone.

I had marked, when at Wick, on several occasions, a thick boulder-clay deposit occupying the southern side of the harbor, and forming an elevated platform, on which the higher parts of Pulteneytown are built; but I had noted little else regarding it than that it bears the average dark-gray color of the flagstones of the district, and that some of the granitic boulders which protrude from its top and sides are of vast size. On my last visit, however, rather more than two years ago, when sauntering along its base, after a very wet morning, awaiting the Orkney steamer, I was surprised to find, where a small slip had taken place during the rain, that it was mottled over with minute fragments of sh.e.l.ls. These I examined, and found, so far as, in their extremely broken condition, I dared determine the point, that they belonged in such large proportion to one species,--the _Cyprina islandica_ of Dr.

Fleming,--that I could detect among them only a single fragment of any other sh.e.l.l,--the pillar, apparently, of a large specimen of _Purpura lapillus_. Both sh.e.l.ls belong to that cla.s.s of old existences,--long descended, without the pride of ancient descent,--which link on the extinct to the recent scenes of being. _Cyprina islandica_ and _Purpura lapillus_ not only exist as living molluscs in the British seas, but they occur also as crag-sh.e.l.ls, side by side with the dead races that have no place in the present fauna. At this time, however, I could but think of them simply in their character as recent molluscs; and as it seemed quite startling enough to find them in a deposit which I had once deemed representative of a period of death, and still continued to regard as obstinately unfossiliferous, I next set myself to determine whether it really _was_ the boulder-clay in which they occurred. Almost the first pebble which I disengaged from the ma.s.s, however, settled the point, by furnis.h.i.+ng the evidence on which for several years past I have been accustomed to settle it;--it bore in the line of its longer axis, on a polished surface, the freshly-marked grooves and scratchings of the iceberg era. Still, however, I had my doubts, not regarding the deposit, but the sh.e.l.ls. Might they not belong merely to the talus of this bank of boulder-clay?--a re-formation, in all probability, not _more_ ancient than the elevation of the most recent of the old coast lines,--perhaps greatly less so. Meeting with an intelligent citizen of Wick, Mr. John Cleghorn, I requested him to keep a vigilant eye on the sh.e.l.ls, and to ascertain for me, when opportunity offered, whether they occurred deep in the deposit, or were restricted to merely the base of its exposed front. On my return from Orkney, he kindly brought me a small collection of fragments, exclusively, so far as I could judge, of _Cyprina islandica_, picked up in fresh sections of the clay; at the same time expressing his belief that they really belonged to the deposit as such, and were not accidental introductions into it from the adjacent sh.o.r.e.

And at this point for nearly two years the matter rested, when my attention was again called to it by finding, in the publication of Mr.

Keith Johnston's admirable Geological Map of the British Islands, edited by Professor Edward Forbes, that other eyes than mine had detected sh.e.l.ls in the boulder-clay of Caithness. "Cliffs of Pleistocene," says the Professor, in one of his notes attached to the map, "occur at Wick, containing boreal sh.e.l.ls, especially _Astarte borealis_."

I had seen the boulder-clay characteristically developed in the neighborhood of Thurso; but, during a rather hurried visit, had lacked time to examine it. The omission mattered the less, however, as my friend Mr. Robert d.i.c.k is resident in the locality; and there are few men who examine more carefully or more perseveringly than he, or who can enjoy with higher relish the sweets of scientific research. I wrote him regarding Professor Forbes's decision on the boulder-clay of Wick and its sh.e.l.ls; urging him to ascertain whether the boulder-clay of Thurso had not its sh.e.l.ls also. And almost by return of post I received from him, in reply, a little packet of comminuted sh.e.l.ls, dug out of a deposit of the boulder-clay, laid open by the river Thorsa, a full mile from the sea, and from eighty to a hundred feet over its level. He had detected minute fragments of sh.e.l.l in the clay about a twelvemonth before; but a skepticism somewhat similar to my own, added to the dread of being deceived by mere surface sh.e.l.ls, recently derived from the sh.o.r.e in the character _of_ sh.e.l.l-sand, or of the edible species carried inland for food, and then transferred from the ash-pit to the fields, had not only prevented him from following up the discovery, but even from thinking of it as such. But he eagerly followed it up now, by visiting every bank of the boulder-clay in his locality within twenty miles of Thurso, and found them all charged, from top to bottom, with comminuted sh.e.l.ls, however great their distance from the sea, or their elevation over it. The fragments lie thick along the course of the Thorsa, where the encroaching stream is scooping out the clay for the first time since its deposition, and laying bare the scratched and furrowed pebbles. They occur, too, in the depths of solitary ravines far amid the moors, and underlie heath, and moss, and vegetable mould, on the exposed hill-sides. The farm-house of Dalemore, twelve miles from Thurso as the crow flies, and rather more than thirteen miles from Wick, occupies, as nearly as may be, the centre of the county; and yet there, as on the sea-sh.o.r.e, the boulder-clay is charged with its fragments of marine sh.e.l.ls. Though so barren elsewhere on the east coast of Scotland, the clay is everywhere in Caithness a sh.e.l.l-bearing deposit; and no sooner had Mr. d.i.c.k determined the fact for himself, at the expense of many a fatiguing journey, and many an hour's hard digging, than he found that it had been ascertained long before, though, from the very inadequate style in which it had been recorded, science had in scarce any degree benefited by the discovery. In 1802 the late Sir John Sinclair, distinguished for his enlightened zeal in developing the agricultural resources of the country, and for originating its statistics, employed a mineralogical surveyor to explore the underground treasures of the district; and the surveyor's journal he had printed under the t.i.tle of "Minutes and Observations drawn up in the course of a Mineralogical Survey of the County of Caithness, ann. 1802, by John Busby, Edinburgh." Now, in this journal there are frequent references made to the occurrence of marine sh.e.l.ls in the blue clay. Mr. d.i.c.k has copied for me the two following entries,--for the work itself I have never seen:--"1802, Sept. 7th.--Surveyed down the river [Thorsa] to Geize; found blue clay-marl, _intermixed with marine sh.e.l.ls_ in great abundance." "Sept. 12th.--Set off this morning for Dalemore. Bored for sh.e.l.l-marl in the 'gra.s.s-park;' found it in one of the quagmires, but to no great extent. Bored for sh.e.l.l-marl in the 'house-park.' Surveyed by the side of the river, and found blue clay-marl in great plenty, _intermixed with marine sh.e.l.ls, such as those found at Geize_. This place is supposed to be about twenty miles from the sea; and is one instance, among many in Caithness, of _the ocean's covering the inland country at some former period of time_."

The state of keeping in which the boulder-sh.e.l.ls of Caithness occur is exactly what, on the iceberg theory, might be premised. The ponderous ice-rafts that went grating over the deep-sea bottom, grinding down its rocks into clay, and deeply furrowing its pebbles, must have borne heavily on its comparatively fragile sh.e.l.ls. If rocks and pebbles did not escape, the sh.e.l.ls must have fared but hardly. And very hardly they have fared: the rather unpleasant casualty of being crushed to death must have been a greatly more common one in those days than in even the present age of railways and machinery. The reader, by pa.s.sing half a bushel of the common sh.e.l.ls of our sh.o.r.es through a barley-mill, as a preliminary operation in the process, and by next subjecting the broken fragments thus obtained to the attritive influence of the waves on some storm-beaten beach for a twelvemonth or two, as a finis.h.i.+ng operation, may produce, when he pleases, exactly such a water-worn sh.e.l.ly debris as mottles the blue boulder-clays of Caithness. The proportion borne by the fragments of one species of sh.e.l.l to that of all the others is very extraordinary. The _Cyprina islandica_ is still by no means a rare mollusc on our Scottish sh.o.r.es, and may, on an exposed coast, after a storm, be picked up by dozens, attached to the roots of the deep-sea tangle. It is greatly less abundant, however, than such sh.e.l.ls as _Purpura lapillus_, _Mytilus edule_, _Cardium edule_, _Littorina littorea_, and several others; whereas in the boulder-clay it is, in the proportion of at least ten to one, more abundant than all the others put together. The great strength of the sh.e.l.l, however, may have in part led to this result; as I find that its stronger and ma.s.sier portions,--those of the umbo and hinge-joint,--are exceedingly numerous in proportion to its slimmer and weaker fragments. "The _Cyprina islandica_," says Dr.

Fleming, in his "British Animals," "is the largest British bivalve sh.e.l.l, measuring sometimes thirteen inches in circ.u.mference, and, exclusively of the animal, weighing upwards of nine ounces." Now, in a collection of fragments of Cyprina sent me by Mr. d.i.c.k, disinterred from the boulder-clay in various localities in the neighborhood of Thurso, and weighing in all about four ounces, I have detected the broken remains of no fewer than _sixteen_ hinge joints. And on the same principle through which the stronger fragments of Cyprina were preserved in so much larger proportion than the weaker ones, may Cyprina itself have been preserved in much larger proportion than its more fragile neighbors. Occasionally, however,--escaped, as if by accident,--characteristic fragments are found of sh.e.l.ls by no means very strong,--such as _Mytilus_, _Tellina_, and _Astarte_. Among the univalves I can distinguish _Dentalium entale_, _Purpura lapillus_, _Turritella terebra_, and _Littorina littorea_, all existing sh.e.l.ls, but all common also to at least the later deposits of the Crag. And among the bivalves Mr. d.i.c.k enumerates,--besides the prevailing _Cyprina islandica_,--_Venus casina_, _Cardium edule_, _Cardium echinatum_, _Mytilus edule_, _Astarte danmoniensis_ (_sulcata_), and _Astarte compressa_, with a _Mactra_, _Artemis_, and _Tellina_.[15] All the determined species here, with the exception of _Mytilus edule_, have, with many others, been found by the Rev. Mr. c.u.mming in the boulder-clays of the Isle of Man; and all of them are living sh.e.l.ls at the present day on our Scottish coasts. It seems scarce possible to fix the age of a deposit so broken in its organisms, on the principle that would first seek to determine its per centage of extinct sh.e.l.ls as the data on which to found. One has to search sedulously and long ere a fragment turns up sufficiently entire for the purpose of specific identification, even when it belongs to a well-known living sh.e.l.l; and did the clay contain some six or eight per cent. of the extinct in a similarly broken condition (and there is no evidence that it contains a single per cent. of extinct sh.e.l.ls), I know not how, in the circ.u.mstances, the fact could ever be determined. A lifetime might be devoted to the task of fixing their real proportion, and yet be devoted to it in vain. All that at present can be said is, that, judging from what appears, the boulder-clays of Caithness, and with them the boulder-clays of Scotland generally, and of the Isle of Man,--for they are all palpably connected with the same iceberg phenomena, and occur along the same zone in reference to the sea-level,--were formed during the _existing_ geological epoch.

These details may appear tediously minute; but let the reader mark how very much they involve. The occurrence of recent sh.e.l.ls largely diffused throughout the boulder-clays of Caithness, at all heights and distances from the sea at which the clay itself occurs, and not only connected with the iceberg phenomena by the closest juxtaposition, but also testifying distinctly to its agency by the extremely comminuted state in which we find them, tell us, not only according to old John Busby, "that the ocean covered the inland country at some former period of time," but that it covered it to a great height at a time geologically recent, when our seas were inhabited by exactly the same mollusca as inhabit them now, and so far as yet appears, by none others. I have not yet detected the boulder-clay at more than from six to eight hundred feet over the level of the sea; but the travelled boulders I have often found at more than a thousand feet over it; and Dr. John Fleming, the correctness of whose observations few men acquainted with the character of his researches or of his mind will be disposed to challenge, has informed me that he has detected the dressed and polished surfaces at least four hundred feet higher. There occurs a greenstone boulder, of from twelve to fourteen tons weight, says Mr. M'Laren, in his "Geology of Fife and the Lothians," on the south side of Black Hill (one of the Pentland range), at about fourteen hundred feet over the sea. Now fourteen or fifteen hundred feet, taken as the extreme height of the dressings, though they are said to occur greatly higher, would serve to submerge in the iceberg ocean almost the whole agricultural region of Scotland. The common hazel (_Corylus avellana_) ceases to grow in the lat.i.tude of the Grampians, at from one thousand two hundred to one thousand five hundred feet over the sea level; the common bracken (_Pteris aquilina_) at about the same height; and corn is never successfully cultivated at a greater alt.i.tude. Where the hazel and bracken cease to grow, it is in vain to attempt growing corn.[16] In the period of the boulder-clay, then, when the existing sh.e.l.ls of our coasts lived in those inland sounds and friths of the country that now exist as broad plains or fertile valleys, the sub-aerial superficies of Scotland was restricted to what are now its barren and mossy regions, and formed, instead of one continuous land, merely three detached groups of islands,--the small Cheviot and Hartfell group,--the greatly larger Grampian and Ben Nevis group,--and a group intermediate in size, extending from Mealfourvonny, on the northern sh.o.r.es of Loch Ness, to the Maiden Paps of Caithness.

The more ancient boulder-clays of Scotland seem to have been formed when the land was undergoing a slow process of subsidence, or, as I should perhaps rather say, when a very considerable area of the earth's surface, including the sea-bottom, as well as the eminences that rose over it, was the subject of a gradual depression; for little or no alteration appears to have taken place at the time in the _relative_ levels of the higher and lower portions of the sinking area: the features of the land in the northern part of the kingdom, from the southern flanks of the Grampians to the Pentland Frith, seemed to have been fixed in nearly the existing forms many ages before, at the close, apparently, of the Oolitic period, and at a still earlier age in the Lammermuir district, to the south. And so the sea around our sh.o.r.es must have deepened in the ratio in which the hills sank. The evidence of this process of subsidence is of a character tolerably satisfactory. The dressed surfaces occur in Scotland, most certainly, as I have already stated on the authority of Dr. Fleming, at the height of fourteen hundred feet over the present sea-level; it has been even said, at fully twice that height, on the lofty flanks of Schehallion,--a statement, however, which I have had hitherto no opportunity of verifying. They may be found, too, equally well marked, under the existing high-water line; and it is obviously impossible that the dressing process could have been going on at the higher and lower levels at the same time. When the icebergs were grating along the more elevated rocks, the low-lying ones must have been buried under from three to seven hundred fathoms of water,--a depth from three to seven times greater, be it remembered, than that at which the most ponderous iceberg could possibly have grounded, or have in any degree affected the bottom.

The dressing process, then, must have been a bit-and-bit process, carried on during either a period of elevation, in which the rising land was subjected, zone after zone, to the sweep of the armed ice from its higher levels _downwards_, or during a period of subsidence, in which it was subjected to the ice, zone after zone, from its lower levels _upwards_. And that it was the lower, not the higher levels, that were first dressed, appears evident from the circ.u.mstance, that though on these lower levels we find the rocks covered up by continuous beds of the boulder-clay, varying generally from twenty to a hundred feet in thickness, they are, notwithstanding, as completely dressed under the clay as on the heights above. Had it been a rising land that was subjected to the attrition of the icebergs, the debris and dressings of the higher rocks would have protected the lower from the attrition; and so the thick acc.u.mulation of boulder-clay which overlies the old coast line, for instance, would have rested, not on dressed, but on undressed surfaces. The barer rocks of the lower levels might of course exhibit their scratchings and polis.h.i.+ngs, like those of the higher; but wherever these scratchings and polis.h.i.+ngs occurred in the inferior zones, no thick protecting stratum of boulder-clay would be found overlying them; and, _vice versa_, wherever in these zones there occurred thick beds of boulder-clay, there would be detected on the rock beneath no scratchings and polis.h.i.+ngs. In order to _dress_ the entire surface of a country from the sea-line and under it to the tops of its hills, and at the same time to cover up extensive portions of its low-lying rocks with vast deposits of clay, it seems a necessary condition of the process that it should be carried on piece-meal from the lower level upwards,--not from the higher downwards.

It interested me much to find, that while from one set of appearances I had been inferring the gradual subsidence of the land during the period of the boulder-clay, the Rev. Mr. c.u.mming of King William's College had arrived, from the consideration of quite a different cla.s.s of phenomena, at a similar conclusion. "It appears to me highly probable," I find him remarking, in his lately published "Isle of man," "that at the commencement of the boulder period there was a gradual sinking of this area [that of the island]. Successively, therefore, the points at different degrees of elevation were brought within the influence of the sea, and exposed to the rake of the tides, charged with ma.s.ses of ice which had been floated off from the surrounding sh.o.r.es, and bearing on their under surfaces, mud, gravel, and fragments of hard rock." Mr.

c.u.mming goes on to describe, in his volume, some curious appearances, which seem to bear direct on this point, in connection with a boss of a peculiarly-compounded granite, which occurs in the southern part of the island, about seven hundred feet over the level of the sea. There rise on the western side of the boss two hills, one of which attains to the elevation of nearly seven hundred, and the other of nearly eight hundred feet over it; and yet both hills to their summits are mottled over with granite boulders, furnished by the comparatively low-lying boss. One of these travelled ma.s.ses, fully two tons in weight, lies not sixty feet from the summit of the loftier hill, at an alt.i.tude of nearly fifteen hundred feet over the sea. Now, it seems extremely difficult to conceive of any other agency than that of a rising sea or of a subsiding land, through which these ma.s.ses could have been rolled up the steep slopes of the hills. Had the boulder period been a period of elevation, or merely a stationary period, during which the land neither rose nor sank, the travelled boulders would not now be found resting at higher levels than that of the parent rock whence they were derived. We occasionally meet on our sh.o.r.es, after violent storms from the sea, stones that have been rolled from their place at low ebb to nearly the line of flood; but we always find that it was by the waves of the rising, not of the falling tide, that their transport was effected. For whatever removals of the kind take place during an ebbing sea are invariably in an opposite direction;--they are removals, not from lower to higher levels, but from higher to lower.

The upper subsoils of Scotland bear frequent mark of the elevatory period which succeeded this period of depression. The boulder-clay has its numerous intercalated arenaceous and gravelly beds, which belong evidently to its own era; but the numerous surface-beds of stratified sand and gravel by which in so many localities it is overlaid belong evidently to a later time. When, after possibly a long protracted period, the land again began to rise, or the sea to fall, the superior portions of the boulder-clay must have been exposed to the action of the tides and waves; and the same process of separation of parts must have taken place on a large scale, which one occasionally sees taking place in the present time on a comparatively small one, in ravines of the same clay swept by a streamlet. After every shower, the stream comes down red and turbid with the finer and more argillaceous portions of the deposit; minute acc.u.mulations of sand are swept to the gorge of the ravine, or cast down in ripple-marked patches in its deeper pools; beds of pebbles and gravel are heaped up in every inflection of its banks; and boulders are laid bare along its sides. Now, a separation, by a sort of was.h.i.+ng process of an a.n.a.logous character, must have taken place in the materials of the more exposed portions of the boulder-clay, during the gradual emergence of the land; and hence, apparently, those extensive beds of sand and gravel which in so many parts of the kingdom exist, in relation to the clay, as a superior or upper subsoil; hence, too, occasional beds of a purer clay than that beneath, divested of a considerable portion of its arenaceous components, and of almost all its pebbles and boulders. This _washed_ clay,--a re-formation of the boulder deposit, cast down, mostly in insulated beds in quiet localities, where the absence of currents suffered the purer particles held in suspension by the water to settle,--forms, in Scotland at least, with, of course, the exception of the ancient fire-clays of the Coal Measures, the true brick and tile clays of the agriculturist and architect.

It is to these superior beds that all the recent sh.e.l.ls yet found above the existing sea-level in Scotland, from the Dornoch Frith and beyond it, to beyond the Frith of Forth, seem to belong. Their period is much less remote than that of the sh.e.l.ls of the boulder-clay, and they rarely occur in the same comminuted condition. They existed, it would appear, not during the chill twilight period, when the land was in a state of subsidence, but during the after period of cheerful dawn, when hill-top after hill-top was emerging from the deep, and the close of each pa.s.sing century witnessed a broader area of dry land in what is now Scotland, than the close of the century which had gone before. Scandinavia is similarly rising at the present day, and presents with every succeeding age a more extended breadth of surface. Many of the boulder-stones seem to have been cast down where they now lie, during this latter time. When they occur, as in many instances, high on bare hill-tops, from five to fifteen hundred feet over the sea-level, with neither gravel nor boulder-clay beside them, we of course cannot fix their period. They may have been dropped by ice-floes or sh.o.r.e-ice, where we now find them, at the commencement of the period of elevation, after the clay had been formed; or they may have been deposited by more ponderous icebergs during its formation, when the land was yet sinking, though during the subsequent rise the clay may have been washed from around them to lower levels. The boulders, however, which we find scattered over the plains and less elevated hill-sides, with beds of the washed gravel or sand interposed between them and the clay, must have been cast down where they lie, during the elevatory ages. For, had they been washed out of the clay, they would have lain, not _over_ the greatly lighter sands and gravels, but _under_ them. Would that they could write their own histories! The autobiography of a single boulder, with notes on the various floras which had sprung up around it, and the various cla.s.ses of birds, beasts, and insects by which it had been visited, would be worth nine-tenths of all the autobiographies ever published, and a moiety of the remainder to boot.

A few hundred yards from the opening of this dell of the boulder-clay, in which I have so long detained the reader, there is a wooded inflection of the bank, formed by the old coast line, in which there stood, about two centuries ago, a meal-mill, with the cottage of the miller, and which was once known as the scene of one of those supernaturalities that belong to the times of the witch and the fairy.

The upper anchoring-place of the bay lies nearly opposite the inflection. A s.h.i.+pmaster, who had moored his vessel in this part of the roadstead, some time in the latter days of the first Charles, was one fine evening sitting alone on deck, awaiting the return of his seamen, who had gone ash.o.r.e, and amusing himself in watching the lights that twinkled from the scattered farm-houses, and in listening, in the extreme stillness of the calm, to the distant lowing of cattle, or the abrupt bark of the herdsman's dog. As the hour wore later, the sounds ceased, and the lights disappeared,--all but one solitary taper, that twinkled from the window of the miller's cottage. At length, however, it also disappeared, and all was dark around the sh.o.r.es of the bay, as a belt of black velvet. Suddenly a hissing noise was heard overhead; the s.h.i.+pmaster looked up, and saw what seemed to be one of those meteors known as falling stars, slanting athwart the heavens in the direction of the cottage, and increasing in size and brilliancy as it neared the earth, until the wooded ridge and the sh.o.r.e could be seen as distinctly from the s.h.i.+p-deck as by day. A dog howled piteously from one of the out-houses,--an owl whooped from the wood. The meteor descended until it almost touched the roof, when a c.o.c.k crew from within; its progress seemed instantly arrested; it stood still, rose about the height of a s.h.i.+p's mast, and then began again to descend. The c.o.c.k crew a second time; it rose as before; and, after mounting considerably higher than at first, again sank in the line of the cottage, to be again arrested by the crowing of the c.o.c.k. It mounted yet a third time, rising higher still; and, in its last descent, had almost touched the roof, when the faint clap of wings was heard as if whispered over the water, followed by a still louder note of defiance from the c.o.c.k. The meteor rose with a bound, and, continuing to ascend until it seemed lost among the stars, did not again appear. Next night, however, at the same hour, the same scene was repeated in all its circ.u.mstances: the meteor descended, the dog howled, the owl whooped, the c.o.c.k crew. On the following morning the s.h.i.+pmaster visited the miller's, and, curious to ascertain how the cottage would fare when the c.o.c.k was away, he purchased the bird; and, sailing from the bay before nightfall, did not return until about a month after.

On his voyage inwards, he had no sooner doubled an intervening headland, than he stepped forward to the bows to take a peep at the cottage: it had vanished. As he approached the anchoring ground, he could discern a heap of blackened stones occupying the place where it had stood; and he was informed on going ash.o.r.e, that it had been burnt to the ground, no one knew how, on the very night he had quitted the bay. He had it re-built and furnished, says the story, deeming himself what one of the old schoolmen perhaps term the _occasional_ cause of the disaster. He also returned the c.o.c.k,--probably a not less important benefit,--and no after accident befel the cottage. About fifteen years ago there was a human skeleton dug up near the scene of the tradition, with the skull, and the bones of the legs and feet, lying close together, as if the body had been huddled up twofold in a hole; and this discovery led to that of the story, which, though at one time often repeated and extensively believed, had been suffered to sleep in the memories of a few elderly people for nearly sixty years.

CHAPTER VII.

Relation of the deep red stone of Cromarty to the Ichthyolite Beds of the System--Ruins of a Fossil-charged Bed--Journey to Avoch--Red Dye of the Boulder-clay distinct from the substance itself--Variation of Coloring in the Boulder-clay Red Sandstone accounted for--Hard-pan how formed--A reformed Garden--An ancient Battle-field--Antiquity of Geologic and Human History compared--Burn of Killein--Observation made in boyhood confirmed--Fossil-nodules--Fine Specimen of _Coccosteus decipiens_--Blank strata of Old Red--New View respecting the Rocks of Black Isle--A Trip up Moray and Dingwall Friths--Altered color of the Boulder-clay--Up the Auldgrande River--Scenery of the great Conglomerate--Graphic Description--Laidlaw's Boulder--_Vaccinium myrtillus_--Profusion of Travelled Boulders--The Boulder _Clach Malloch_--Its zones of Animal and Vegetable Life.

The ravine excavated by the mill-dam showed me what I had never so well seen before,--the exact relation borne by the deep red stone of the Cromarty quarries to the ichthyolite beds of the system. It occupies the same place, and belongs to the same period, as those superior beds of the Lower Old Red Sandstone which are so largely developed in the cliffs of Dunnet Head in Caithness, and of Tarbet Ness in Ross-s.h.i.+re, and which were at one time regarded as forming, north of the Grampians, the a.n.a.logue of the New Red Sandstone. I paced it across the strata this morning, in the line of the ravine, and found its thickness over the upper fish-beds, though I was far from reaching its superior layers, which are buried here in the sea, to be rather more than five hundred feet. The fossiliferous beds occur a few hundred yards below the dwelling-house of Rose Farm. They are not quite uncovered in the ravine; but we find their places indicated by heaps of gray argillaceous shale, mingled with their characteristic ichthyolitic nodules, in one of which I found a small specimen of Cheiracanthus. The projecting edge of some fossil-charged bed had been struck, mayhap, by an iceberg, and dashed into ruins, just as the subsiding land had brought the spot within reach of the attritive ice; and the broken heap thus detached had been shortly afterwards covered up, without mixture of any other deposit, by the red boulder-clay. On the previous day I had detected the fish-beds in another new locality,--one of the ravines of the lawn of Cromarty House,--where the gray shale, concealed by a covering of soil and sward for centuries, had been laid bare during the storm by a swollen runnel, and a small nodule, inclosing a characteristic plate of Pterichthys, washed out. And my next object in to-day's journey, after exploring this ravine of the boulder-clay, was to ascertain whether the beds did not also occur in a ravine of the parish of Avoch, some eight or nine miles away, which, when lying a-bed one night in Edinburgh, I remembered having crossed when a boy, at a point which lies considerably out of the ordinary route of the traveller. I had remarked on this occasion, as the resuscitated recollection intimated, that the precipices of the Avoch ravine bore, at the unfrequented point, the peculiar aspect which I learned many years after to a.s.sociate with the ichthyolitic member of the system; and I was now quite as curious to test the truth of a sort of vignette landscape, transferred to the mind at an immature period of life, and preserved in it for full thirty years, as desirous to extend my knowledge of the fossiliferous beds of a system to the elucidation of which I had peculiarly devoted myself.

As the traveller reaches the flat moory uplands of the parish, where the water stagnates amid heath and moss over a thin layer of peaty soil, he finds the underlying boulder-clay, as shown in the chance sections, spotted and streaked with patches of a grayish-white. There is the same mixture of arenaceous and aluminous particles in the white as in the red portions of the ma.s.s; for, as we see so frequently exemplified in the spots and streaks of the Red Sandstone formations, whether Old or New, the coloring matter has been discharged without any accompanying change of composition in the substance which it pervaded;--evidence enough that the red dye must be something distinct from the substance itself, just as the dye of a handkerchief is a thing distinct from the silk or cotton yarn of which the handkerchief has been woven. The stagnant water above, acidulated by its various vegetable solutions, seems to have been in some way connected with these appearances. In every case in which a crack through the clay gives access to the oozing moisture, we see the sides bleached, for several feet downwards, to nearly the color of pipe-clay; we find the surface, too, when it has been divested of the vegetable soil, presenting for yards together the appearance of sheets of half-bleached linen: the red ground of the clay has been acted upon by the percolating fluid, as the red ground of a Bandanna handkerchief is acted upon through the openings in the perforated lead, by the discharging chloride of lime. The peculiar chemistry through which these changes are effected might be found, carefully studied, to throw much light on similar phenomena in the older formations. There are quarries in the New Red Sandstone in which almost every ma.s.s of stone presents a different shade of color from that of its neighboring ma.s.s, and quarries in the Old Red the strata of which we find streaked and spotted like pieces of calico. And their variegated aspect seems to have been communicated, in every instance, not during deposition, nor after they had been hardened into stone but when, like the boulder-clay, they existed in an intermediate state. Be it remarked, too, that the red clay here,--evidently derived from the abrasion of the red rocks beneath,--is in dye and composition almost identical with the substance on which, as an unconsolidated sandstone, the bleaching influences, whatever their character, had operated in the Palaeozoic period, so many long ages before;--it is a repet.i.tion of the ancient experiment in the Old Red, that we now see going on in the boulder-clay. It is further worthy of notice, that the bleached lines of the clay exhibit, viewed horizontally, when the overlying vegetable mould has been removed, and the whitened surface in immediate contact with it paired off, a polygonal arrangement, like that a.s.sumed by the cracks in the bottom of clayey pools dried up in summer by the heat of the sun. Can these possibly indicate the ancient rents and fissures of the boulder-clay, formed, immediately after the upheaval of the land, in the first process of drying, and remaining afterwards open enough to receive what the uncracked portions of the surface excluded,--the acidulated bleaching fluid?

The kind of ferruginous pavement of the boulder-clay known to the agriculturist as _pan_, which may be found extending in some cases its iron cover over whole districts,--sealing them down to barrenness, as the iron and bra.s.s sealed down the stump of Nebuchadnezzar's tree,--is, like the white strips and blotches of the deposit, worthy the careful notice of the geologist. It serves to throw some light on the origin of those continuous bands of clayey or arenaceous ironstone, which in the older formations in which vegetable matter abounds, whether Oolitic or Carboniferous, are of such common occurrence. The _pan_ is a stony stratum, scarcely less indurated in some localities than sandstone of the average hardness, that rests like a pavement on the surface of the boulder-clay, and that generally bears atop a thin layer of sterile soil, darkened by a russet covering of stunted heath. The binding cement of the _pan_ is, as I have said, ferruginous, and seems to have been derived from the vegetable covering above. Of all plants, the heaths are found to contain most iron. Nor is it difficult to conceive how, in comparatively flat tracts of heathy moor, where the surface water sinks to the stiff subsoil, and on which one generation of plants after another has been growing and decaying for many centuries, the minute metallic particles, disengaged in the process of decomposition, and carried down by the rains to the impermeable clay, should, by acc.u.mulating there, bind the layer on which they rest, as is the nature of ferruginous oxide, into a continuous stony crust. Wherever this _pan_ occurs, we find the superinc.u.mbent soil doomed to barrenness,--arid and sun-baked during the summer and autumn months, and, from the same cause, overcharged with moisture in winter and spring. My friend Mr. Swanson, when schoolmaster of Nigg, found a large garden attached to the school-house so inveterately sterile as to be scarce worth cultivation; a thin stratum of mould rested on a hard impermeable pavement of _pan_, through which not a single root could penetrate to the tenacious but not unkindly subsoil below. He set himself to work in his leisure hours, and bit by bit laid bare and broke up the pavement. The upper mould, long divorced from the clay on which it had once rested, was again united to it; the piece of ground began gradually to alter its character for the better; and when I last pa.s.sed the way, I found it, though in a state of sad neglect, covered by a richer vegetation than it had ever borne under the more careful management of my friend. This ferruginous pavement of the boulder-clay may be deemed of interest to the geologist, as a curious instance of deposition in a dense medium, and as ill.u.s.trative of the changes which may be effected on previously existing strata, through the agency of an overlying vegetation.

I pa.s.sed, on my way, through the ancient battle-field to which I have incidentally referred in the story of the Miller of Resolis.[17] Modern improvement has not yet marred it by the plough; and so it still bears on its brown surface many a swelling tumulus and flat oblong mound, and--where the high road of the district pa.s.ses along its eastern edge--the huge gray cairn, raised, says tradition, over the body of an ancient Pictish king. But the contest of which it was the scene belongs to a profoundly dark period, ere the gray dawn of Scottish history began. As shown by the remains of ancient art occasionally dug up on the moor, it was a conflict of the times of the stone battle-axe, the flint arrow-head, and the unglazed sepulchral urn, unindebted for aught of its symmetry to the turning-lathe,--times when there were heroes in abundance, but no scribes. And the cairn, about a hundred feet in length and breadth, by about twenty in height, with its long h.o.a.ry hair of overgrown lichen waving in the breeze, and the trailing club-moss shooting upwards from its base along its sides, bears in its every lineament full mark of its great age. It is a mound striding across the stream of centuries, to connect the past with the present. And yet, after all, what a mere matter of yesterday its extreme antiquity is! My explorations this morning bore reference to but the later eras of the geologist; the portion of the geologic volume which I was attempting to decipher and translate formed the few terminal paragraphs of its concluding chapter. And yet the _finis_ had been added to them for thousands of years ere this latter antiquity began. The boulder-clay had been formed and deposited; the land, in rising over the waves, had had many a huge pebble washed out of its last formed red stratum, or dropped upon it by ice-floes from above; and these pebbles lay mottling the surface of this barren moor for mile after mile, bleaching pale to the rains and the sun, as the meagre and mossy soil received, in the lapse of centuries, its slow accessions of organic matter, and darkened around them. And then, for a few brief hours, the heath, no longer solitary, became a wild scene of savage warfare,--of waving arms and threatening faces,--and of human lives violently spilled, gus.h.i.+ng forth in blood; and, when all was over, the old weathered boulders were heaped up above the slain, and there began a new antiquity in relation to the pile in its gathered state, that bore reference to man's short lifetime, and to the recent introduction of the species. The child of a few summers speaks of the events of last year as long gone by; while his father advanced into middle life, regards them as still fresh and recent.

I reached the Burn of Killein,--the scene of my purposed explorations,--where it bisects the Inverness road; and struck down the rocky ravine, in the line of the descending strata and the falling streamlet, towards the point at which I had crossed it so many years before. First I pa.s.sed along a thick bed of yellow stone,--next over a bed of stratified clay. "The little boy," I said, "took correct note of what he saw, though without special aim at the time, and as much under the guidance of a mere observative instinct as Dame Quickly, when she took note of the sea-coal fire, the round table, the parcel-gilt goblet, and goodwife Keech's dish of prawns dressed in vinegar, as adjuncts of her interview with old Sir John when he promised to marry her. These are unequivocally the ichthyolitic beds, whether they contain ichthyolites or no." The first nodule I laid open presented inside merely a pale oblong patch in the centre, which I examined in vain with the lens, though convinced of its organic origin, for a single scale.

Proceeding farther down the stream, I picked a nodule out of a second and lower bed, which contained more evidently its organism,--a finely-reticulated fragment, that at first sight reminded me of some delicate festinella of the Silurian system. It proved, however, to be part of the tail of a Cheiracanthus, exhibiting--what is rarely shown--the interior surfaces of those minute rectangular scales which in this genus lie over the caudal fin, ranged in right lines. A second nodule presented me with the spines of _Diplacanthus striatus_; and still farther down the stream,--for the beds are numerous here, and occupy in vertical extent very considerable s.p.a.ce in the system,--I detected a stratum of bulky nodules charged with fragments of Coccosteus, belonging chiefly to two species,--_Coccosteus decipiens_ and _Coccosteus cuspidatus_. All the specimens bore conclusive evidence regarding the geologic place and character of the beds in which they occur; and in one of the number, a specimen of _Coccosteus decipiens_, sufficiently fine to be transferred to my knapsack, and which now occupies its corner in my little collection, the head exhibits all its plates in their proper order, and the large dorsal plate, though dissociated from the nail-