The Old Red Sandstone; or, New Walks in an Old Field

by Hugh Miller

Let us attempt bringing our knowledge of the present to bear upon the past. The larger crustaceæ of the British seas abound most on iron-bound coasts, where they find sheltering places in the deeper fissures of sea-cliffs covered up by kelp and tangle, or under the lower edges of detached boulders, that rest unequally on uneven platforms of rock, amid forests of the rough-stemmed cuvy. We may traverse sandy or muddy shores for miles together, without rinding a single crab, unless a belt of pebbles lines the upper zone of beach, where the forked and serrated fuci first appear, or a few weed-covered fragments of rock here and there occur in groups on the lower zones. In this formation, however, the bottom must have been formed of mingled sand and mud, and yet the crustacea were abundant. How account for the fact? There is, in most instances, an interesting conformity between the character of the ancient rocks, in which we find groups of peculiar fossils, and the habitats of those existences of the present creation which these fossils most resemble. The fisherman casts his nets in a central hollow of the Moray Frith, about thirty fathoms in depth, and draws them up foul with masses of a fetid mud, charged with multitudes of that curious purple-colored zoophyte the sea-pen, invariably an inhabitant of such recesses. The graptolite of the most ancient fossiliferous rocks, an existence of unequivocally the same type, occurs in greatest abundance in a finely-levigated mudstone, for it, too, was a dweller in the mud. In like manner, we may find the ancient Modiola of the Lias in habitats analogous to those of its modern representative the muscle, and the encrinite of the Mountain Limestone fast rooted to its rocky platform, just as we may see the Helianthoida and Ascidioida of our seas fixed to their boulders and rocky skerries. But is not analogy at fault in the present instance? Quite the reverse. Mark how thickly these carbonaceous impressions cover the muddy-colored and fissile sandstones of the formation, giving evidence of an abundant vegetation. We may learn from these obscure markings, that the place in which they grew could have been no unfit habitat for the crustaceous tribes.

There is a little, land-locked bay on the southern shore of the Frith of Cromarty, effectually screened from the easterly winds by the promontory on which the town is built, and but little affected by those of any other quarter, from the proximity of the neighboring shores. The bottom, at low ebb, presents a level plain of sand, so thickly covered by the green grass-weed of our more sheltered sandy bays and estuaries, that it presents almost the appearance of a meadow. The roots penetrate the sand to the depth of nearly a foot, binding it firmly together; and as they have grown and decayed in it for centuries, it has acquired, from the disseminated particles of vegetable matter, a deep leaden tint, more nearly approaching to black than even the dark gray mudstones of Balruddery. Nor is this the only effect: the intertwisted fibres impart to it such coherence, that, where scooped out into pools, the edges stand up perpendicular from the water, like banks of clay; and where these are hollowed into cave-like recesses,—and there are few of them that are not so hollowed,—the recesses remain unbroken and unfilled for years. The weeds have imparted to the sand a character different from its own, and have rendered it a suitable habitat for numerous tribes, which, in other circumstances, would have found no shelter in it. Now, among these we find in abundance the larger crustaceans of our coasts. The brown edible crab harbors in the hollows beside the pools; occasionally we may find in them an overgrown lobster, studded with parasitical shells and zoöphytes—proof that the creature, having attained its full size, has ceased to cast its plated covering. Crustaceans of the smaller varieties abound. Hermit crabs traverse the pools, or creep among the weed; the dark green and the dingy, hump-backed crabs occur nearly as frequently; the radiata cover the banks by thousands. We find occasionally the remains of dead fish left by the retreating tide; but the living are much more numerous than the dead; for the sand-eel has suffered the water to retire, and yet remained behind in its burrow; and the viviparous blenny and common gunnel still shelter beside their fuci-covered masses of rock. Imagine the bottom of this little bay covered up by thick beds of sand and gravel, and the whole consolidated into stone, and we have in it all the conditions of the deposit of Balruddery—a mud-colored, arenaceous deposit, abounding in vegetable impressions, and enclosing numerous remains of crustaceans, fish, and radiata, as its characteristic organisms of the animal kingdom. There would be but one circumstance of difference: the little bay abounds in shells; whereas no shells have yet been found in the mudstones of Balruddery, or the gray sandstones of the same formation, which in Forfar, Fife, and Moray shires represent the Cornstone division of the system.

Ages and centuries passed, but who can sum up their number? In England, the depth of this middle formation greatly exceeds that of any of the other two; in Scotland, it is much less amply developed; but in either country it must represent periods of scarce conceivable extent. I have listened to the controversies of opposite schools of geologists, who, from the earth's strata, extract registers of the earth's age of an amount amazingly different. One class, regarding the geological field as if under the influence of those principles of perspective which give to the cottage in front more than the bulk and altitude of the mountain behind, would assign to the present scene of things its thousands of years, but to all the extinct periods united merely their few centuries; while with their opponents, the remoter periods stretch out far into the bygone eternity, and the present scene seems but a narrow strip running along the foreground. Both classes appeal to facts; and, leaving them to their disputes, I have gone out to examine and judge for myself. The better to compare the present with the past, I have regarded the existing scene merely as a formation—not as superficies, but as depth; and have sought to ascertain the extent to which, in different localities, and under different circumstances, it has overlaid the surface.

The slopes of an ancient forest incline towards a river that flows sluggishly onwards through a deep alluvial plain, once an extensive lake. A recent landslip has opened up one of the hanging thickets. Uprooted trees, mingled with bushes, lie at the foot of the slope, half buried in broken masses of turf; and we see above a section of the soil, from the line of vegetation to the bare rock. There is an under belt of clay, and an upper belt of gravel, neither of which contains any thing organic; and overtopping the whole we may see a dark-colored bar of mould, barely a foot in thickness, studded with stumps and interlaced with roots. Mark that narrow bar: it is the geological representative of six thousand years. A stony bar of similar appearance runs through the strata of the Wealden: it, too, has its dingy color, its stumps, and its interlacing roots; but it forms only a very inconsiderable portion of one of the least considerable of all the formations; and yet who shall venture to say that it does not represent a period as extended as that represented by the dark bar in the ancient forest, seeing there is not a circumstance of difference between them?

We descend to the river side. The incessant action of the current has worn a deep channel through the leaden-colored silt; the banks stand up perpendicularly over the water, and downwards, for twenty feet together,—for such is the depth of the deposit,—we may trace layer after layer of reeds, and flags, and fragments of driftwood, and find here and there a few fresh-water shells of the existing species. In this locality, six thousand years are represented by twenty feet. The depth of the various fossiliferous formations united is at least fifteen hundred times as great.

We pursue our walk, and pass through a morass. Three tiers of forest trees appear in the section laid open by the stream, the one above the other. Overlying these there is a congeries of the remains of aquatic plants, which must have grown and decayed on the spot for many ages after the soil had so changed that trees could be produced by it no longer; and over the whole there occur layers of mosses, that must have found root on the surface after the waters had been drained away by the deepening channel of the river. The six thousand years are here represented by that morass, its three succeeding forests, its beds of aquatic vegetation, its bands of moss, and the thin stratum of soil which overlies the whole. Well, but it forms, notwithstanding, only the mere beginning of a formation. Pile up twenty such morasses, the one over the other; separate them by a hundred such bands of alluvial silt as we have just examined a little higher up the stream; throw in some forty or fifty thick beds of sand to swell the amount; and the whole together will but barely equal the Coal Measures, one of many formations.

But the marine deposits of the present creation have been, perhaps, accumulating more rapidly than those of our lakes, forests, or rivers? Yes, unquestionably, in friths and estuaries, in the neighborhood of streams that drain vast tracts of country, and roll down the soil and clay swept by the winter rains from thousands of hill-sides; but what is there to lead to the formation of sudden deposits in those profounder depths of the sea, in which the water retains its blue transparency all the year round, let the waves rise as they may? And do we not know that, along many of our shores, the process of accumulation is well nigh as slow as on the land itself? The existing creation is represented in the little land-locked bay, where the crustacea harbor so thickly, by a deposit hardly three feet in thickness. In a more exposed locality, on the opposite side of the promontory, it finds its representative in a deposit of barely nine inches. It is surely the present scene of things that is in its infancy! Into how slender a bulk have the organisms of six thousand years been compressed! History tells us of populous nations, now extinct, that flourished for ages: do we not find their remains crowded into a few streets of sepulchres? 'Tis but a thin layer of soil that covers the ancient plain of Marathon. I have stood on Bannockburn, and seen no trace of the battle. In what lower stratum shall we set ourselves to discover the skeletons of the wolves and bears that once infested our forests? Where shall we find accumulations of the remains of the wild bisons and gigantic elks, their contemporaries? They must have existed for but comparatively a short period, or they would surely have left more marked traces behind them.

When we appeal to the historians, we hear much of a remote antiquity in the history of man: a more than twilight gloom pervades the earlier periods; and the distances are exaggerated, as objects appear large in a fog. We measure, too, by a minute scale. There is a tacit reference to the threescore and ten years of human life; and its term of a day appears long to the ephemera. We turn from the historians to the prophets, and find the dissimilarity of style indicating a different speaker. Ezekiel's measuring-reed is graduated into cubits of the temple. The vast periods of the short-lived historian dwindled down into weeks and days. Seventy weeks indicated to Daniel, in the first year of Darius, the time of the Messiah's coming. Three years and a half limit the term of the Mohammedan delusion. Seventeen years have not yet gone by since Adam first arose from the mould; nor has the race, as such, attained to the maturity of even early manhood. But while prophecy sums up merely weeks and days, when it refers to the past, it looks forward into the future, and speaks of a thousand years. Are scales of unequally graduated parts ever used in measuring different portions of the same map or section—scales so very unequally graduated, that, while the parts in some places expand to the natural size, they are in others more than three hundred times diminished? If not,—for what save inextricable confusion would result from their use,—how avoid the conclusion, that the typical scale employed in the same book by the same prophet represents similar quantities by corresponding parts, whether applied to times of outrage, delusion, and calamity, or set off against that long and happy period in which the spirit of evil shall be bound in chains and darkness, and the kingdom of Christ shall have come? And if such be the case—if each single year of the thousand years of the future represents a term as extended as each single year of the seventeen years of the past—if the present scene of things be thus merely in its beginning—should we at all wonder to find that the formation which represents it has laid down merely its few first strata?

The curtain again rises. A last day had at length come to the period of the middle formation; and in an ocean roughened by waves, and agitated by currents, like the ocean which flowed over the conglomerate base of the system, we find new races of existences. We may mark the clumsy bulk of the Holoptychius conspicuous in the group; the shark family have their representatives as before; a new variety of the Pterichthys spreads out its spear-like wings at every alarm, like its predecessors of the lower formation; shoals of fish of a type more common, but still unnamed and undescribed, sport amid the eddies; and we may see attached to the rocks below substances of uncouth form and doubtful structure, with which the oryctologist has still to acquaint himself. The depositions of this upper ocean are of a mixed character: the beds are less uniform and continuous than at a greater depth. In some places they consist exclusively of sandstone, in others of conglomerate; and yet the sandstone and conglomerate seem, from their frequent occurrence on the same platform, to have been formed simultaneously. The transporting and depositing agents must have become more partial in their action than during the earlier period. They had their foci of strength and their circumferences of comparative weakness; and while the heavier pebbles which composed the conglomerate were in the course of being deposited in the foci, the lighter sand which composes the sandstone was settling in those outer skirts by which the foci were surrounded. At this stage, too, there are unequivocal marks, in the northern localities, of extensive denudation. The older strata are cut away in some places to a considerable depth, and newer strata of the same formation deposited unconformably over them. There must have been partial upheavings and depressions, corresponding with the partial character of the depositions; and, as a necessary consequence, frequent shiftings of currents. The ocean, too, seems to have lessened its general depth, and the bottom to have lain more exposed to the influence of the waves. And hence one cause, added to the porous nature of the matrix, and the diffused oxide, of the detached, and, if I may so express myself, churchyard character of its organisms.