Page:Geology and Mineralogy considered with reference to Natural Theology, 1837, volume 1.djvu/82

 78 forms of genera which exist at the present time. This ad-mixture was first noticed by M. Desnoyers, in the marine formations of the Faluns of Touraine. Similar admixtures have been found in Bavaria, and near Darmstadt. Many

blende, to be 7.29. (Geol. Researches, p. 379.)—The compact lava of Calabria contains 10. of carbonate of lime, and the basalt of Saxony 9.5.

We may, in like manner, refer the origin of those large quantities of silex, which constitute the chert and flint beds of stratified formations, to the waters of hot springs, holding siliceous earth in solution, and depositing it on exposure to reduced degrees of temperature and pressure, as silex is deposited by the hot waters that issue from the geysers of Iceland.