Page:VCH Warwickshire 1.djvu/31

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GEOLOGY

THE beginnings of the history of our county are to be found written on the stony tablets of the rocks, in records by the side of which the Saxon chronicle, the Roman epitaph, are nothing but the closing passages of a many-chaptered story.

Through a study of the various operations by which to-day the materials of the land are everywhere being worn down, carried away by streams, and redeposited in seas and lakes as beds of gravel, as sandbanks, or as mudflats, it is possible in some measure not only to realize the physical conditions which prevailed in our district in those far-off ages, but also to people again those ancient waters with their shelly denizens, and to form some idea of the animal and vegetable inhabitants of those long since vanished lands.

For the beds of sandstone, clay, and limestone which make up the bulk of our Warwickshire rocks are comparable in all respects with accumulations forming at the present day ; they were for the most part laid down in estuaries, seas and lakes ; and many of the inhabitants of the waters, and not a few of the animals, insects, and plants from the adjacent land became entombed in the gathering sediments. In the course of ages these areas of deposition by slow upheaval have been more than once converted into land ; and it is clear that these new lands would consist of layers of hardened sediments (' stratified ' rocks), and that the entombed organic remains would be the ' fossils ' of succeeding times. And so long as any particular part of our area stood up as a land-tract above the waters, there the continuity of deposit would be broken ; certain beds would be missing. Subsequent submergence of the whole area would result in the burying of everything under newer sheets of sediment which, while resting unconformably on the worn-down ruins of the old land-mass, would have a closer parallelism to the deposits immediately preceding themselves. In the sequel we shall meet with several instances of these great gaps in the geological succession.

Further, by a knowledge of the physical and climatic conditions specially favourable to certain forms of life of to-day, we arrive at some idea of the state of things prevalent in our area during the formation of many of these fossiliferous rocks, and can distinguish marine from lacustrine deposits, and deep-water formations from those laid down along a shore. As we examine in succession the ascending series of sediments it is found too that there has been a steady change in

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