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summer by melted snow and ice. A remarkable uniformity of climate would prevail amid the archipelagoes of the temperate and polar oceans, where the tepid waters of equatorial currents would freely circulate

"We might expect, therefore, in the summer of the 'great year,' which we are now considering, that there would be a predominance of tree-ferns and plants allied to palms and arborescent grasses in the islands of the wide ocean, while the dicotyledonous plants and other forms now most common in temperate regions would almost disappear from the earth. Then might those genera of animals return, of which the memorials are preserved in the ancient rocks of our continents. The huge iguanodon might reappear in the woods, and the ichthyosaur in the sea, while the pterodactyle might flit again through umbrageous groves of tree-ferns. Coral reefs might be prolonged once more beyond the arctic circle, where the whale and the narwal now abound; and droves of turtles might wander again through regions now tenanted by the walrus and the seal.

"But not to indulge too far in these speculations, I may observe, in conclusion, that however great during the lapse of ages may be the vicissitudes of temperature in every zone, it accords with this theory that the general climate should not experience any sensible change in the course of a few thousand years, because that period is insufficient to affect the leading features of the physical geography of the globe." —Principles, Book i., chap, vii., pp. 121-131.

This is perhaps the most ingenious and elaborate

theory presented by Sir Charles Lyell in the whole course of his speculations to account for the geological conditions which he supposes to have once existed; and were the reality of those conditions admitted, it would in some respects form a plausible solution of the effects he refers to them. Instead, however, of being established by a scientific induction, it is a mere supposition. Not a pretence is made of demonstrating it by direct and indubitable evidence. Every one of its propositions that is made the basis of the inference he aims to sustain by it, is preceded by an IF, tall

"As the mast Of some great admiral."

The only consideration he offers to support it is, that if the conditions and processes he supposes are admitted, they seemingly furnish a natural and adequate explanation of the variations of temperature and peculiar forms of vegetable and animal life, which he holds characterized the earth at certain stages of its ancient history. It contributes nothing, therefore, towards the verification of his general theory respecting the force by which the strata were formed, and the vast series of ages their deposition occupied. To treat it as a fact; to exalt it to the rank of a positive proof of that great hypothesis; to make it the basis of a rejection and confutation of the testimony of the Scriptures respecting the date of the creation of the earth, is truly an extraordinary misjudgment. The fact that it apparently presents an explication of the conditions and events it is invented to explain is no evidence of its truth. To admit the validity of such a method of establishing a system, would be at a blow to annihilate every fact of experience, and overthrow every truth of science. The theory of Buffon, of Burnet, of Whiston, of La Place, respecting the origin and laws of the world, might, by such a process, be as effectually established as that of Newton.

Its want of pertinence to the immediate purpose for which he employs it is not, however, its only disqualification for the support of his system; as he deserts in it the great postulate on which he professedly proceeds, that the forces that are producing changes in the earth's surface act without intermission and with a uniform energy; and tacitly assumes that those forces at certain crises operate with thousands of times their ordinary intensity, and give birth to changes immeasurably above the usual range of their effects; as it is inconsistent with the conditions he prescribes to himself, to suppose that under such a process, "the general climate should not experience any sensible change in the course of a few thousand years; because that period is insufficient to affect the leading features of the physical geography of the

globe," which he supposes to be so wholly revolutionized. It would be impossible that such an elevation of a continent with lofty mountains in one part of the ocean, should take place simultaneously with a depression of an equal area of land with mountains of the same height in another; and yet at the same time, "the proportion of dry land to sea continue the same; the volume of the land rising above the sea be a constant quantity; and not only its mean but its extreme height be liable only to trifling variations; and both the mean and extreme depths of the sea be invariable," unless the change took place instantaneously, or at least was completed in so brief a space that the period occupied in it would not be of any geological consideration. For on no other condition could the proportion of dry land to sea, the volume of land above the level of the sea, and both the mean and extreme height of the mountains, continue the same. If the elevation, for example, of the supposed continent in the sea between Greenland and the Orkneys, took place at the same rate as the depression of the Himalaya mountains and Hindostan, and advanced so gradually as to be prolonged through a vast round of ages, it is manifest that Hindostan would descend beneath it thousands of years before the corresponding part of the arctic continent could emerge from its bosom. The submersion of Hindostan would take place in the early stages of the revolution; the ascent of the other at its close. During the vast period therefore that intervened, the proportion of dry land to sea, and of the volume of land rising above the level of the sea, instead of remaining constant, would, to that extent, be altered; and consequently an equal change would be produced in the mean and extreme depth of the ocean. Moreover, as there are great inequalities in the surface of Hindostan, a large part consisting of low plains, part of high table lands and elevated valleys, and part rising into lofty mountain ranges— other subordinate variations in the proportion of land to sea would take place while the submersion was in progress. A depression of two to three hundred feet would carry beneath the waters all the lower plain of the Ganges and a wide tract along the eastern coast of the peninsula, probably together equal to one third of the whole. A further descent of five hundred feet would leave nothing above the waves except the mountains, the table lands, and the high valleys that lie between the ranges or heights of the Himalaya. The table lands that slope from the Ghauts on the western side of the peninsula to the opposite coast on the bay of Bengal, rise from 1700 to 2800 or 3000 feet above the level of the ocean; and the lower of the high valleys of the Himalaya, 2000 feet. They would be submerged therefore by an additional descent of 1200 to 2200 feet. A further depression

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