Aldrich, Thomas Bailey, 1836-1907 · Boston, CT : Hall and Locke · leaf 47
to read and under-stand are becoming more and more clear. It has been already said that unstratified rocks arethose which have been at some period, whether latelyor very long ago, in a liquid state from intense heat, and whichhave since cooled,either quickly orslowly, crystalhz-ing as they… … What the Earths Crust is Made of 23 Secondly.—Plutonic Rocks, such as granite. Thesehave been slowly cooled deep down in the earth underheavy pressure. There is also a class of rocks, called metamorphicrocks, including some kinds of marble. These are,strictly speaking, crystalline rocks, and yet…
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