Page:Popular Science Monthly Volume 48.djvu/286

274* silica, would go on until the affinities of the acids were satisfied, and there would be a separation of silica taking the form of quartz, and the production of sea-water holding in solution, besides the chlorides and the sulphates of sodium, calcium, and magnesium, salts of ammonium and other metallic bases. The atmosphere, being thus deprived of its volatile chlorine and sulphur compounds, would gradually approximate to that of our own time, but would differ in the greater amount of carbonic-acid gas."

And the meteorologist Abbe, in the course of remarks made before the Philosophical Society of Washington in 1889, expressing the propriety of wholly rejecting the idea that the earth was once a molten globe, stated: "The study of geological climate during and since the formation of Azoic metamorphic strata has led me to adopt the conclusion that surface geology, like volcanic, does not demand excessive temperatures; it seems to me most reasonable to assume that the surface was never much warmer than 250° F., but to allow that this temperature may have prevailed at the close of the Archaic epoch.

"At this temperature all the water of the ocean would exist only as vapor and clouds in the atmosphere. The steady, hot rain from the atmosphere would rapidly disintegrate the surface rocks. Small seas and lakes of water saturated with alkalies and salts would at once begin to form the rocks that we know as metamorphic and archæan. The covering thus formed would contribute to diminish the rate of cooling of the interior mass, thus allowing the atmosphere to cool down to its present condition and deposit the most of its moisture."

In the rocks formed earliest after Archæan time, to which geological age only crystalline rocks devoid of fossils belong, there are found aquatic relics of organisms with calcareous skeletons which when living bore a close generic relation to organic forms which are confined to oceanic waters at the present time. Among these early inhabitants of the sea were corals, crinoids, sea urchins, and starfishes, and many others there doubtless were which, although they require the saline constituents of the sea to live upon, had no calcareous skeletons, and consequently have not been preserved in a fossil state. The remains are found deposited in the lower Silurian as well as the Devonian, Carboniferous, Jurassic, and Cretaceous formations.

But apart from these deductions concerning the saltness of the primeval ocean there is direct evidence that the waters of the sea in the early part of Paleozoic time were highly saline, for there were deposited from the waters of the Silurian sea saliferous strata which constitute the Onondaga salt group and the Trenton and Chazy limestone series, in which the relics of marine organ