Page:Transactions of the Geological Society, 1st series, vol. 2.djvu/264

254 In the smooth and undulating surface of the chalk hills, in the banks of gravel of great extent, in the deep hollows often filled up again by the detritus of regular strata, in the direction of the principal ridges and valleys, we cannot but recognize the effect of water, the only agent which we know to be capable of producing such appearances.

But under what influence has this power, fully equal to such a purpose, been directed? What could give sufficient energy to a body at other times so tranquil? These are questions of which the complete solution will perhaps ever remain in obscurity.

Yet already we have had sufficient proofs that the sea has not always maintained the same relative level; that it has alternately risen and fallen; although to ascertain the distance of time between these changes be absolutely beyond the reach of human sagacity.

Let us then imagine an ocean in a violent state of agitation. The hills of chalk, and the last depositions of the globe are torn to pieces; the flints are dispersed and rounded by attrition against each other; finally, currents carry them to great distances, and lodge them in hollows worn by the waters, or form them into ridges and other accumulations. Fragments of other rocks are intermixed; forests are torn up and levelled, and, with the vegetable soil, formed into morasses. The inhabitants of the land are destroyed and buried deep in this dreadful ruin. But a more surprizing revolution ensues. Disorder ends; the waters retire; the northern continents are disclosed, become fitted for vegetation, and are peopled by the tribes of animals which now inhabit them.