Pumice is an example of extrusive igneous rock. The word extrusive means that the magma was forced onto the earth's surface and cooled in a matter of hours. Granite is an example of intrusive igneous ...

Sedimentary rocks are made up of pieces of older rocks (igneous, metamorphic, and sedimentary) and organic remains (shells, bone, etc.). When rocks break apart from erosion they are transported by ...

Introduction -- Physical properties of magma -- Intrusion of magma -- Forms of igneous bodies -- Cooling of igneous bodies and other diffusion processes -- Classification of igneous rocks -- ...

In my last column, I wrote about the locations where you can find igneous rocks that were formed from lava. The metarhyolite and metabasalt described in the column are known as extrusive rocks, those ...

THIS book is intended for two classes of reader, namely, the student beginning the study of the igneous rocks, and the geologist seeking a refresher course. As a result, the beginner will need careful ...

THE closing years of the nineteenth century witnessed a revival of interest in the petrology of gneous rocks, which must be regarded as marking an important stage in the development of that subject.