. Key to the upper Devonian of southern New York. Paleontology; Paleontology. Look at the rocks themselves. What are they? Some are soft and decompose rapidly; others are harder and withstand the elements for a longer period. But all in course of time will dis- integrate and form clay or sand, accordingly as they were shaly or sandy rocks. Such rocks are in fact nothing but hardened clayey or sandy mud. The shells in them prove that the sands and mud before hardening formed a part of an old sea-bottom where sea-shells lived, died, and were buried beneath more sand and mud washed over them by i
. Key to the upper Devonian of southern New York. Paleontology; Paleontology. Look at the rocks themselves. What are they? Some are soft and decompose rapidly; others are harder and withstand the elements for a longer period. But all in course of time will dis- integrate and form clay or sand, accordingly as they were shaly or sandy rocks. Such rocks are in fact nothing but hardened clayey or sandy mud. The shells in them prove that the sands and mud before hardening formed a part of an old sea-bottom where sea-shells lived, died, and were buried beneath more sand and mud washed over them by inflowing rivers. If the water is deep, or the bottom of the sea is gradually sinking, the thickness of such deposits may become very great—several thousands of feet. The lower beds become intensely compressed and hardened after the lapse of long ages, especially if they are subjected to volcanic heat and activity. If then a movement of the earth's crust takes place and these lowT-lying beds are raised above sea level they are visible to man in quarries and other places as here- tofore stated, and he terms them "hard rocks"; the shells and other traces of life they contain are called fossils. That the conditions under which the rocks in southern New York were deposited or formed may be clear to the mind of the reader the following two outline maps have been inserted (Fig's. 3 and 4). They both show the same area (see degrees of Lat. jfr 77* *v ^L 44* AW<r - The mtttor geqgrafhiml feet* tt*ts cf tht$ land area during Upper Dewnftin titnet are unknown JJfe ddiraiutacks and other mountains to the Rmth and the Taconta range to the east were doubtless then more prominent than they are today <tf. F*g- 3- and Long.), the one approximately as the area appeared in De- vonian times, the other as it appears to-day—showing especially. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration an
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectpaleontology, bookyea
