POSTSCRIPT.

Since this work was completed, the "Principles of Geology," by Mr. Lyell, have appeared; a work of very great talent, and full of interesting research and information on the secondary causes in constant action upon the earth. This able writer has, however, taken, in some respects, a new line of theory, and is as desirous of accounting for the phenomena on the surface of the earth, without the aid of any unusual or preternatural convulsion, as other geologists have been to press into their service a constant repetition of deluges and disasters. He sets out upon the principle of Playfair, "that amid all the revolutions of the globe, the economy of nature has been uniform, and her laws are the only things that have resisted the general movement. The rivers and the rocks, the seas and the continents, have changed in all their parts; but the laws which direct those changes, and the rules to which they are subject, have remained invariably the same.”—Title Page.

Thus we find, that while Cuvier inculcates the doctrine of numerous deluges, alternately of salt and of fresh water, Mr. Lyell endeavours to account for all things without the aid of any general deluge, though he considers local deluges as amongst the ordinary occurrences of nature, and producing violent local effects. The Mosaic deluge appears to be looked upon either as a fable, or as a less general catastrophe, than it is usually conceived to have been; and, as a supporter of the Mosaic account of it, it is probable that I shall be classed among those "physico-theological writers," who, in the early days of science, wrote, it is true, but little worthy of saving them from the contempt with which they are here treated.

As may easily be conceived of a theory wherein all things are to be accounted for by the slow and gradual march of na

tural secondary causes, Mr. Lyell's system requires an unlimited period of time for its completion; and in tracing the errors into which other philosophers have fallen, he thinks there can be no wonder if such should be the case, when hundreds of years are often reckoned instead of thousands, and thousands instead of millions. Mr. Lyell accounts for the elevation of mountain ridges, by successive up-heavings of Volcanic force, small in degree, but of frequent repetition; and, having time at command, he finds no difficulty in this process.

But notwithstanding this theoretical argument in the "Principles of Geology," so distinctly opposed by so many facts in nature; and, with regard to at least one deluge, so totally opposed to history, and the traditions of all nations, Mr. Lyell has taken a very learned and extended view of secondary causes and of secondary formations. On the evidences to be derived from the fossil remains of quadrupeds, however, he has encountered the same difficulties as professor Buckland, without having succeeded in throwing any greater degree of light on the obscurities of that subject. His mode of accounting for the remains of elephants in the icebergs of the polar seas, and for the other tropical remains of animals and vegetables over the temperate and polar regions, proceeds upon the same principle, and is open to the same glaring objections as the theories of Dr. Buckland and baron Čuvier.

With regard, however, to the actual age of the world, and the actually short period during which secondary causes have been in action on the portions of the globe we now inhabit, we may safely refer the subject to the powerful evidence produced in such abundance, and with so much industry, by this author himself. I have had occasion in a note, in another part of this treatise, (see Chapter V.) to notice the startling facts produced by Mr. Lyell, with respect to the quantity of mud daily imported into the sea by the single river, the Ganges: it is there admitted by Mr. Lyell, that even at the lowest estimate, viz. one part in a hundred, of mud, in the waters of that river, there is imported daily into the Bay of Bengal, “a mass more than equal in weight and bulk to the great pyramid of Egypt."* It does not suit the theory of Mr. Lyell to admit the correctness of major Rennell's estimate, in which it is shown, with much clearness, that the daily deposit of that sin

gle river, in the flood season, instead of only once, is nearly equal to SEVENTY-FOUR times the weight of that gigantic monument. If we even divide the difference between these two authors, and admit the amount to be not more than than from thirty to forty times the size of the pyramid per day, and if we extend our view of a similar action to all the rivers of the earth, and then consider the comparative actual extent of the whole mass of secondary formations over the surface of the primitive globe, we shall at once perceive that such violent transporting powers, acting for a million of years, must have produced a mass of secondary formations, infinitely greater than what actually exists upon the earth, which may, probably, be considered as of not greater medium thickness than about one mile. But one million of years is not sufficient for those who advocate the view of the subject adopted by Mr. Lyell; no author of that school has ever yet been able to bound his views within any nameable period; and we may, with much truth, transpose their own animadversion, and consider it as not very wonderful if they find themselves involved in inextricable confusion and difficulty, when they calculate upon thousands of years, instead of hundreds, and millions instead of thousands.

CHAPTER I.

Our ideas of the real extent of Objects on the Earth's Surface often erroneous.-True height of Mountains.-Depths of the Ocean. -Of Mines.-Of Volcanic Foci.-Eruptions of Mud containing Fish.-Volcanoes only in Secondary Formations.—True Scale on which to view the Earth.-Form of the Earth.-Newton's Demonstrations.-Gravity and Centrifugal Force.False inferences drawn from Newton's Hypothesis.—True Primitive Creations.-Density of the Earth.-Reflections arising from the Subject.-The Days of Creation.

On entering on a subject so extensive as the consideration of the entire globe, and with the intention of first viewing it in a general way, before we proceed to the examination of its particular parts, our first object ought to be to attain the necessary elevation from whence this full and general view may be obtained.

Man, in his little sphere of action, on a minute portion of its surface, finds his ideas so confined, that he is constantly misled by them, in forming conceptions of objects beyond common, every day observation. Thus, when traversing the stupendous Alpine regions of the earth, the mind of a stranger is overcome with the unusual appearances of things; and it is in such scenes that the geologist but too often forms erroneous notions of the "fracture and ruin of the solid crust of the earth."* In like manner, an idea of immensity is attached to

"In the midst of such scenes, the geologist feels his mind invigorated; the magnitude of the appearances before him extinguishes all the little and contracted notions he may have formed in his closet; and he learns that it is only by visiting and studying these stupendous works, that he can form an adequate conception of the great relations

the fathomless abysses of the great deep, or to the profound sources of volcanic fires. These objects, however, great as as they may appear in the common scale of human comparison, almost vanish when the larger and more correct scale, on which the whole globe has been framed, is applied to them. The entire diameter of the earth is computed at about 8000 miles. Now, the loftiest peak upon the earth's surface,* though it rises to the enormous elevation of upwards of twentysix thousand feet, is but five such miles above the general surface of the ocean. In like manner, the greatest depths of the ocean sink into comparative insignificance, when this scale is applied to them. For although the actual measurement of these depths is, and ever must remain, beyond the reach of human art, yet we have the strongest reasons (almost amounting to certainty) for supposing, from analogy, that the form and surface of the bed of the sea have no greater variation from the general level than those of the surface of the dry land; and, consequently, that while there may be depths in the ocean extending to four or five miles, by far the greater of the crust of the globe, and of its mode of formation.”—Edinburgh Encyclopedia, Mineralogy.

It has been well observed, that greatness is only a comparative quality. It is true, that Alpine scenery is well calculated to enlarge the mind, and to extinguish notions, formed on a more contracted view of the earth's surface. But even this enlarged view becomes contracted in its turn, unless the earth be viewed upon its own proper scale.

* Dhawalageri, in Asia. Mount Blanc is not quite three miles above the same level. On taking the mean height of twenty-nine of the greatest elevations in the Old World, it is found to be only one mile and three-quarters. The mean height of an equal number in the New World is nearly two miles above the level of the sea.

+ We find it a general rule, probably without any material exception, that where a country is low, and the shore flat, the neighbouring sea is shallow in about the same proportion. On the contrary, where a coast is mountainous, and the cliffs high and precipitous, there we find the sea of very considerable depth, and nearly of the same form under water as above. We have this point ably illustrated in the survey of the German Ocean, with sections of the depths, in six different lines, from the shores of Great Britain to those of Holland, Denmark, and Norway, by Mr. Stevenson, in 1820. We come to the same conclusion on a small, but generally correct scale, by considering any fresh-water lake, the shores of which present a variety of scenery. In all the Swiss lakes it is very striking; and in some, where the immediate shores are of great elevation, the bottom of the lake has not yet been found.

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