Читать книгу The Romance of Modern Geology. Describing in simple but exact language the making of the earth with some account of prehistoric animal life онлайн

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Pits, quarries, and mines that cut down still deeper into the earth and lay it bare bring before our eyes most impressive testimony regarding the ancient changes of the land. Suppose, by way of further illustration, that underneath a bed of sand full of oyster shells there lies a dark brown band of peat. This substance, composed of mosses and other water-loving plants, is formed in boggy places by the growth of marshy vegetation. Below the peat there might occur a layer of soft white marl full of lake shells, such as may be observed on the bottom of many lakes at the present time. These three layers—oyster beds, peat, and marl—would be like a family pedigree showing the history of the place. The bottom layer of white marl would show that there was once a lake. The next layer of peat would show that by the growth of marshy vegetation the lake became choked up and was gradually changed into a swamp and then a morass. The other layer of oyster shells would show that the ground was afterwards submerged by the sea. The present condition of the ground would show that the sea at last retired, and the place passed into dry land as it is to-day.