The Age of the Earth

“We must look for a moment at the common notions regarding the fundamental rocks. In the ordinary teaching of geology, we are given to understand that the foundation-rock of the globe is granite, and that the fluid matter supposed to underlie the solid crust is melted granite; that the difference between the matter ejected from volcanoes and the fundamental rock lies in the mode of cooling: the former, solidifying in the open air, becomes lava, basalt, or the like; while the latter, slowly cooled under enormous pressure, becomes the mineral compound called granite.