bulk of the fluid which it displaces. Thus, if a rock be twice as heavy, bulk for bulk, as water, then when immersed in that fluid, it loses just one half its weight. A man may lift a stone under water with great ease, but if not aware of the above fact, he will be astonished to find that he cannot, with all his might, raise it above the surface.

There is no difficulty in conceiving that immense blocks of rock may be moved by water, since the weight lost by immersion, is in exact proportion to the bulk; and therefore if a little brook will move a pebble, by the same law, a great flood will transport a mountain. The blocks of granite found on the opposite side of the lake of Geneva, were probably carried there by the action of the deluge, after which the retiring waters scooped out the lake, and left both in the situation in which they are now found. Many of the plains in the north of Europe, exhibit on their surfaces, large blocks of granite, called boulders, with their sharp angles worn off, showing that they have been rolled from a distance. Their surfaces never exhibit the smoothness of sea-worn pebbles, nor do their forms shew the effects of long-continued friction, like rocks which are found on the shores of the ocean, a proof that the catastrophe which forced them from their original situations was not of long continuance. Sir James Hall has even discovered the traces of such movements on rocks now in their original situations in the vicinity of Edinburgh. That district consists of hills and valleys, the surfaces of which are strewed with the wrecks of former rocks, which have been moved from their ancient positions by some mighty pow

er.

Channels, or furrows may be observed on the surfaces of solid rocks, across which these have been forced. The clay, covering the surfaces of these rocks, being removed, they are found to resemble a road along which many heavy bodies have been recently dragged, as if every heavy fragment had made a scratch of greater or less depth as it passed. These furrows are parallel to the general direction in which the diluvial current passed, as shewn by the forms of the hills and valleys.

That the diluvial waters reached the summits of lofty mountains, is evident from the boulder blocks of Mount Blanc, being thrown over on the high acclivities of Mount Jura. Professor Buckland says, that the Alps and Carpathians, as well as every other mountainous region which

he has visited, bear the same evidence of having been modified by the force of water, as do the hills of the lower regions.

Besides the evidence which the situations of rocky masses exhibit of a great flood, there are proofs of the same, to be found almost every where among the hills and valleys. Thus many hills have been formed by the removal of the earth, which forms the valley between them, circumstances proving that such valleys did not always exist, but that the strata forming the two hills were once continuous,

Suppose that on digging wells, on two hills separated by a valley, there should be found a bed of gravel ten feet thick, then a layer of clay, then a bed of chalk, &c., and that these formations should correspond exactly with each other, both in respect to kind, direction and thickness; then the inference would be unavoidable, that these strata once continued through the valley, and that both the hills and valley were formed by the removal of the earth from the latter, and that this must have been effected by a stream of water now existing, or by a great flood. But in the cases to which we refer no such streams exist, nor from appearances ever did exist, there being no sources of water by which they could be supplied.

No adequate cause can therefore be assigned for such an effect, except it be the Noachian deluge. The adjoining cut shows the two hills; the correspondence of the strata through each, and the wells by which they are pierced. Such examples it is believed are of very common occurrence, and would often be observed were due notice taken of the strata when digging wells on opposite hills.

Immense beds of sand and water-worn pebbles are found deposited in places and situations which cannot be accounted for on any supposition, except that of a temporary and sweeping flood of waters.

Mr. de la Beche under the head of "Erratic Block Group," "Geological Manual," p. 157, has described and figured a deposition of gravel which occurs at Warren Point, near Dawlish, and which we copy as an illustration of the subject. The figure is a section of the point, and is a mixed example of a fault, and of transported gravel upon it, b b, conglomerates, or pudding stones, and cc, strata of the red sandstone formation, fractured or broken into faults, by the dykes f f, so that continuous strata are displaced as seen in the cut. Upon these fractured strata rests a bed of gravel a a, composed of chalk, flints, and green flinty sand, mixed with a few pebbles similar to those in the conglomerates b b. This sand has evidently been deposited since the fracture, for it rests quietly upon it, and appears never to have been disturbed since its deposition. The chalk and green sand of this district have once covered very considerable spaces, though the latter is now seen only on Haldon Hills, near this section, but separated from it by an intervening valley. There are many other dislocations so covered on the same coast, (Plymouth); where these appearances can be observed with the greatest ease, especially at low

water.

"It might be supposed," says Mr. De La Beche," that these chalk flints and pieces of chert, (a flinty stone,) were merely the remains of superincumbent masses of chalk and green sand, which have been destroyed, by meteorie agents, the harder parts falling down on the top of the fracture. We can scarcely consider this physically probable, or even possible; for it supposes, the removal of more than 600 feet of sandstone and conglomerate, (for not until that height above this section would the green sand and chalk come on,) without scarcely leaving any of the pebbles, or large masses of the red sandstone, while the flints and cherts, which belonged to the upper, and consequently first destroyed rocks, remain."

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Let us now consider," continues our author, "another class of appearances. Over the whole of this district, (Plymouth,) where transported gravel occurs, the surface of the rocks, (it being of no importance what they

happen to be,) is drilled into cavities and holes, similar to those well known on the chalk of the east of England. The following sections will illustrate this.

a, a, gravel, principally of flint and chert, resting in a hollow of the red sandstone, b, b, between Teignmouth and Dawlish, the lines in the gravel following the outline of the cavity.

a, a, in the next figure, is gravel composed in a great measure of flints, among which are some large rounded pieces of silicious breccia, resting on cavities in pipe-clay.

"Other examples might easily be adduced, but these are here given, because the geological student can easily observe them. They seem to point to some general agent, which in its passage over the land, has produced similar effects on various rocks, forming cavities and depositing fragments, transported from greater or less distances."

Mr. De La Beche further remarks, "that the form of the valleys in that district are gentle and rounded, and such as no complication of meteoric causes, that ingenuity can imagine, seems capable of producing; that numerous valleys occur on the lines of the faults; and that the detritus, (broken rocks,) is dispersed in a way that cannot be accounted for by the present action of mere atmospheric waters. I will more particularly remark," says he, "that on Great Haldon Hill, about 900 feet above the sea, pieces of rock which must have been derived from levels not greater than 700 or 800 feet, and even less, occur in the superficial gravel. They certainly are rare, but may be discovered by diligent search. I there found pieces of red sandstone, porphyry, and a compact silicious rock, not uncommon in the greywacke of the vicinity, where all the rocks occur at a lower level than the summit of Haldon, and where certainly they could not have been carried by rains or rivers, unless the latter be supposed to delight in running up hill."

In continuing this subject with respect to the lowlands of Sidmouth and Lyme, Mr. De La Beche says, "it may sometimes be possible, with the aid of ingenuity, to produce a case of transport by a long continuance of such

natural effects as are now seen, but in other situations, such explanations seem altogether valueless, and unphilosophical.

Not only are gravels brought from various distances, but even huge blocks, the transport of which, by actual causes, into their present situations seem physically impossible. Professor Buckland mentions that he found among the transported gravel of Durham, twenty varieties of slate and greenstone, which do not occur in places nearer than the lake district of Cumberland. Professor Sedgwick remarks that the boulders of Shap granite, which is so peculiar as not to be confounded with any other rocks in the North of England, are not only drifted over the hills of Appleby, but have been scattered over the plain of new red sand stones; rolled over the great central chain of England into the plains of Yorkshire;embedded in transported matter of the Zees; and even carried to the eastern coast of the Island.—Ann. of Phil. 1825.

Between the Thames and the Tweed, pebbles, and even blocks of rock, are discovered, of such a character that they have been considered, we believe, by all competent judges, as having been derived from the coast of Norway, where only similar rocks are known to exist.

Mr. Phillips states, that the diluvial accumulation in Holderness, on the coast of Yorkshire, is composed of a base of clay, containing fragments of pre-existing rocks, varying in roundness and size. The rocks from which the fragments appear to have been transported are found, some in Norway; others in the Highlands of Scotland, and in the mountains of Cumberland-others, in the north western and western parts of Yorkshire; and no inconsiderable portion appears to have come from the seacoast of Durham, and in the neighborhood of Whitby. In proportion to the distance they have travelled is the degree of roundness they have acquired.-Phillips' Illus. Geol. Yorkshire.

In this country, similar phenomena almost every where present themselves to the eye of the observer. Beds of water-worn pebbles, such as are now found only on the borders of the sea; and immense blocks of granite lying in situations to which it is evident they must have been transported, and where no causes now in operation, could possibly have placed them, are not uncommon occur

rences.