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State of the OceaN. 87 When we view the various demolitions from the earlieft difcoverable period to the neweft, we find in them fuch differences, as {hew that the contents of the water of the globe mud have changed by de grees, and that all its depofitions; form beautiful and connected feries. The oldeft rocks, which, are pure chemical precipitates, arej compofed principally of filiceous, argillaceous and magnefian. earths. The rocks, as Granite, Gneifs, and Mica- flate, contain metals that are of cotemporaqeous formation with them, and that fcarcely occur in newer periods ; thefe are. Tin, Molybdena, and Tungften. 1, 1—. a • Thisftateof the water of the globe, however, alters gradually and remarkably, as we approach the newer periods, by the appearance of Limeflorte in quan- v tity, Coal, and Salt, and the difappearance of old and the appearance of new metals. Befides this general fucceffion, (which will afterwards be particularly confidered), difcoverable in the pro- duaions of different periods, we have inftances of the repetition of certain produ&s at confiderable intervals, and in formations of different aeras and kind. In a feries of this kind, all the members have general charaaers of agreement, and the in dividual members bear charaaers expreffive, not only of the period of their formation, but alfo of the circumftances under which they were formed. Such a feries, as we have already mentioned, is denominated a Principal Formation Suite, or Series-