III. Other singular records of the age under review have been preserved in a similar manner; for the ocean itself has not failed to impress its own movements on the sands laved by its waters. Hence the ripple-mark has been detected, a recognized object of the science, and a phenomenon to be seen in the sandstones of all ages and in all countries. The new red, from the stiller waters perhaps in which it was formed, contains everywhere beautifully minute and perfect delineations of the kind. The furrowed sandstones form a class by themselves, being selected in the neighborhood of Brighton, as paving-stones for the streets, and in the stable-yards as a protection for the horses against slipping. The traces often of the more destructive violence of the sea, even of recent date, in leveling villages, sweeping down plains, undermining cliffs, overwhelming proud navies, are completely obliterated or forgotten, while here the records of its still voice are indelibly engraven on the rock.
Observe other markings as you walk along the sea-shore on a summer’s eve; how every wavelet that breaks upon the beach leaves its tiny indentation, until the whole surface becomes furrowed as the reflex of the ever-shifting flood; there spring up on every side innumerable hillocks of sand, little blisters through which you detect the movements of a creature within, and then the trail of the sea-worm is visible all over. These were vermes and annelides burrowing in the sands, in those ancient times, with instincts and habits precisely the same. “We find,” says Dr. Buckland, “on the surface of slabs, both of the calcareous grit, and Stonesfield slate, near Oxford, and on sandstones of the Wealden formation, in Sussex and Dorsetshire, perfectly-preserved and petrified castings of marine worms, at the upper extremity of holes bored by them in the sand, while it was yet soft at the bottom of the water; and within the sandstones, traces of tubular holes in which the worms resided.” Nature here has changed little from her first models; the same element, which is now chaffing upon the same materials of sand and rock, has possessed through all time the same ingredients of life-stirring action.
IV. Nor has the atmosphere—that twin ocean of upper earth—failed to give evidence of the properties and laws by which it was then governed. The rain-drop, a singular unmistakeable marking, has also been detected upon the sandstones of the period. These impressions have been described and adopted by men of science as the true veritable indices of the showers and cloud-falls of the old world. The very size of the drop may be measured, the thick pattering of the rain compared with the scanty or copious showers of the present day, and the very point detected from which the wind blew on the day that these showers fell. What a curious tale is thus disclosed, by a record, no modern version of which any one will stay to read a moment longer than he can escape to shelter from its influences. Astronomers tell us, upon the faith of the Herschels, the measurements of Strüve, Bessel, and Mädler, that, notwithstanding that light travels at the inconceivable speed of two hundred and thirteen thousand miles in a second, the light from Uranus, one of our own planetary system, does not reach our earth until two hours after it has been emitted from its orb; that, from the edge of the Milky Way, a star of the twelfth magnitude, careering in all the effulgence of that luminous ether, cannot be descried until four thousand years after the ray has begun its journeyings; and yet more, as the results of the most rigid induction, it is revealed to us that the spots of clouds, which under the resolving power of the best telescopes seem more oval flakes or small specks of whiteness, are really distinct and independent systems, floating at such an immeasurable distance that the light has to wander millions of years before it can break in its faintest morning-streak upon our horizon. Mark the analogy, therefore, ere you scoff at the credulity of the geologist, or the power of the rain-drop to transmit an image of itself through so many revolutions and ages of the earth’s history. How impalpable a substance is light! how readily effaced its impressions, or intercepted its brilliant colorings, by the interposition of the frailest creation of matter—an insect’s wing, the covering of a leaf, the disc of a flower-petal. But the light, thus easily obliterated or dimmed on earth, has been maintaining its own solitary independent course through every medium, every change, of upper and netherworlds. The moment of its efflux from remotest orb, in depth of infinite space, gave to every particle of that feebly or intensely luminous beam, a separate being and direction, with no return back to its parent source. And now, says the intelligent astronomer, as it drops gently into the searcher of his telescope, that is a ray from yon far distant unresolvable cluster of stars, or of astral systems, for millions of years traveling through these incalculable heights, when as yet the Chaldee sages had pointed no instrument to the heavens, nor the learned of Memphis recorded an observation. Can you deny to other matter, argues the geologist, a similar tenacity of self-preservation, the vitality of impress which merely records the uniformity of the laws and constitution of nature, and which intimates that, through all past time, there were showers to cheer and to refresh the products of the earth? Truth becomes more marvelous than fiction when traced in researches such as these—showing the illimitable range over time and space permitted to human inquiry—and producing, at the same time, things both of heaven and of earth scarcely to be dreamt of in human philosophy.
V. But the economic and practically useful, no less than the speculative or fanciful, form constituents of the new red sandstone formation. The strata are not only indented with impressions of strange and doubtful origin; they inclose, like those of the carboniferous system, treasures of the greatest value; and nature, in ceasing to abound in one kind of product, has been no less exuberant in others, equally contributive to the comfort and convenience of man. In this class of rocks are situated our great deposits of rock-salt and gypsum, of the former of which, beside supplying the demands of the home market, the mines of Cheshire alone export from Liverpool upward of half a million of tons weight. The distribution of the saline mineral is very general over the earth, and by no means constant in its geognostic position; as, for example, in Galicia, it is found among the tertiary deposits; in New York, it occupies the middle of the silurians; while in Hungary, Poland, and England, it is uniformly associated with the new red sandstone. Rock-salt has been long known to and prized by mankind; it became an object of taxation or tribute six hundred and forty years before the Christian era, as narrated of Ancus Martins, “salinarum vectigal instituit;” and hence centuries afterward, when Great Britain was in possession of the Romans, the legions received salt as part of their pay or “salary.” Our richest mines are in Cheshire, and along the districts watered by the Dee, the Weaver, and the Mersey. The beds, or rather masses, are imperfectly stratified, and vary in thickness from a few inches to 120 feet and upward: gypsum and variegated marls may be regarded as constants in the formation, the gypseous deposits sometimes attaining the enormous depth of 150 feet.
We speak of the beds of gypsum as deposits, in common with those of the sandstone matrix in which they are imbedded. It appears, however, on inquiring into the theory of their origin, that they are not strictly such in the true sense of deposits—originally as gypseous deposits—but altered limestones, metamorphosed by the action of gases which have escaped from beneath, and permeated the calcareous mass. The carbonates of lime have been converted into the sulphates of lime, by means of gaseous emanations produced in unknown volcanic depths. Even the dolomitic member of the group is supposed to have a like metamorphic origin; the needful elementary agencies having entered into the parent limestone, and converted it into the magnesian type. Why nature should not have done these things directly, at the first off-throw, science could not, perhaps, very satisfactorily answer the skeptically inquiring mind; but, as the ingredients are all chemically well known, and more especially as there is a vast laboratory ever at work, filled with all kinds of elements, in her subterranean regions, any hypothesis of formation is as rapidly established as it is conceived, and the interest of the subject humanly speaking augmented. The celebrated Berzelius, when questioned on the point, had his ready solution of the problem, easily derived from his unparalleled stores of chemical knowledge:—“Give me a substance containing sulphur—admit the presence of the vapors of sulphur, or sulphurous or sulph-hydrous vapors,—let limestone be also present, and water on the surface or in the atmosphere, and we shall readily have gypsum.” The origin of the saltness of the ocean is still a mystery in science; equally involved in doubt and conjecture is that of the other member of the series, the rock-salt formation. The generally adopted theory, however, is, that it was dependent on volcanic agency for development, as it both contains, and is uniformly associated with, the acids, and other materials found in connection with volcanoes. The chlorides of sodium and gypsum, for example, are at present sublimed from volcanic vents; vapors charged with sulphuric acid are constantly issuing from the same sources; and these passing through or associated with the saline waters of the period, must have aided in the formation of rock-salt and gypsum, which occur more frequently in irregular masses than in true stratified deposits. An additional corroboration of the theory is inferred from the circumstance, that the gypsum accompanying the rock-salt is anhydrous, that is, free from water before exposure to the action of the atmosphere. Hence the conclusion, that the consolidation of both the rock-salt and the gypsum must have been effected by the agency of heat, as, by means of aqueous deposition, a hydrometric influence would have been sensibly perceived.
Wonderful certainly is all this—the inclosing, the consolidation, the arrangement of these remarkable substances. The sea, in the first instance, may readily and abundantly have supplied all the elements of the formation; but how collected and retained, crystallized and incrusted, layer upon layer, over the rocky bottom and volcanic inner chambers, are points still of nice geological inquiry. The celebrated salt mines of Cracow, in Poland, are wondrous operations of the art of man, into the still more wondrous products and recesses of nature. Here the entire arrangements of a city are almost perfected; the streets, marketplace, chapel, rivers, reservoirs, grottoes, and all the requirements of comfort and safety gleaming in a blaze of saline crystals.
“Scoop’d in the briny rock long streets extend
Their hoary course, and glittering domes ascend;
Down the bright steeps, emerging into day,
Impetuous fountains burst their headlong way,