Class-Book of Science and Literature

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1869 edition. Excerpt: ...and therefore the remains in them are more numerous and better preserved. They are of great thickness, and are found in Wales, Cumberland, North-west Scotland, Ireland, North America, and elsewhere. Along with the older rocks beneath them, they everywhere form mighty rugged peaked mountains, like those of Wales and the Highlands; and their worn rugged aspect is due to their being so long subjected to wasting influences from their great antiquity. All these earlier rock-formations, from the Metamorphic to the Silurian, are exceedingly rich in mineral wealth, most of the precious metals being obtained from them. Shooting through their hard crystalline masses, we find veins of iron, copper, silver, and gold; and, from the presence of these metals, bare mountain tracts have teeming populations, where even the sheep with difficulty finds its scanty food. Organic Remains.--The fossil remains are all of the very lowest kinds of life. Sea-weeds, shells of different kinds, and some Crustacea, especially one that occurs abundantly in the next formation, called the trilobite, have been discovered. The tracks and burrows of worms, formed in the sand of the ancient seas, may also be seen perforating these hard masses. Scenery of Period.--During the Cambrian age, quiet seas heaved their waters as now, tenanted with shells and crab-like creatures, while waves rolled on the sandy shores, over which worms crawled, and into which they burrowed; interesting as shewing that creatures had then the same kinds of habits as now, and that what we can see any day along our own shores sends us back to the distant ages when the world was young! IV.--Silurian System. Description.--The Silurian System contains rocks less changed by heat than those below, and...