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Excerpt from Everyday Life in Prehistoric Times For the ordinary man, it seems sufficient to suppose that if you find the same kind of fossil in the limestones of America and England, and find the limestone itself in the same relative position to the other strata, then if the two are not twin brothers they must be most nearly related. The modern scientist can find out by observation how long the delta of a river, or any other form of sediment, takes to accumulate. In this way they form a scale by which they can also estimate the age of the older deposits. To revert then to our strata: The Chart (p. xi) shows the Geological Periods and the stratified rocks. These latter are shown in the order in which they were deposited, starting from the bottom upwards. To illustrate this more fully, we give a section across Wales and England (Fig.3). We have Snowdon in the west at A. Its base at 1 is built on Pre-Cambrian, Cambrian, and Ordovician rocks, and there is an outcrop of these more to the east. Eruptive rocks appear at 3, and the Silurian at 4. The Devonian at 5, and at 6 the Gneiss at Malvern. All this west part of England has been disturbed, and the many skins or strata of the earth distorted by enormous physical disturbances. At B are the Malverns, and here there is a fault or break in the stratum, but as we go east the geological conditions become easier to understand; 8 and 9 are Red Marl or Triassic; 10 the Lias. At C we have the Cotswold Hills composed of the Oolites, 11; the Lias and Oolites are Jurassic. This is overlaid by the Greensand at 12, and the Chalk of the Chiltern Hills at 13; these are Cretaceous. Then we have the Eocene beds at 14. We shall not be very concerned with the primary rocks in our study of prehistoric life, but shall soon come across references to those of the Mesozoic, or Secondary Period. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.
