Page:The Journal of geology (IA journalofgeology11893univ).pdf/201

from the chaotic fluid, the water became purer. Mountains were conceived of as the local points of original crystallization which drew to them, in the process, the minerals from the general fluid. As the waters gradually withdrew by evaporation and sinking into the interior caverns, they became clarified and capable of supporting organic life.

Kirwan says (p. 26): "The level of the ancient ocean being lowered to the height of 8,500 or 9,000 feet, then and not before, it began to be peopled with fish." (Under the name fish he included shell-fish, and all other petrifactions). The plains were formed of depositions from the water of argillaceous, siliceous and ferruginous particles, mingled with those derived by erosion from the already protruding mountains. All the rocks above the height mentioned, he observed, quoting from testimony of numerous travelers, are lacking in fossils; even the limestones are crystalline or "primative" limestones and marbles. These observations were cited in refutation of Buffon's "error" in claiming that all limestones were derived from comminuted shells. According to some authorities, primitive mountains should include rocks of even less height than 8,000 feet, and the occasional presence of fossils at a greater elevation was by them accounted for by their transference to that elevation by the deluge. This account of Kirwan's will suggest the way in which the rock formation came at to be first called "gebirge," or mountains. Rocks were supposed to lie as they were originally formed, and thus in classifying rocks the larger aggregates were naturally mountain masses. As the conception of movements in the earth's crust with folding and displacement come into the science, the idea of classification and grouping of rocks was retained, but that their grouping was based upon present massing above the surface as mountains ceased to be accepted as truth. In the German language the term "Gebirge" was retained, and apparently with restricted meaning. Kirwan apparently translated the term directly into English as mountains. Formation however took the place of mountain, as applied to rock classification, in the early part of the century.