20. The second effect of the cooling process was to liquefy certain vaporous substances in the air, which were precipitated to the surface of the ground. There were then shower and lakes of sulphur and bitumen, veritable stream of iron, copper, lead, and other heated metals infiltrating themselves into the fissures which constitute today the metallic veins and arteries of the Earth.
Under the influence of these different agents the granite surface experienced successive decomposition. Combinations were formed which resulted in primitive rocks distinct from the granite rocks, but in confused masses, and without regular stratifications.
Then came the waters, which, falling upon a burning soil, vaporized anew, fell again and again in torrents until the temperature permitted them to rest upon the soil in a liquid state.
At the formation of the granite rocks the regular series of geologic periods commence. To the six principal periods it is proper to add that of the primitive incandescent state of the globe.