The student of petrography, if possible, shoulf make an attempt to get the complet story of each sample. Under indeal conditions he would start with the examination and systematic sampling of rock masses in the field. Frequently a study of field exposure yields information that is invaluable in the laboratory study of hand specimens and thin sections. Samples are collected in the filed under a …
The Science of Petrology-Petrology is the science of rocks, that is, of the more or less definite units of which the earth is built. In the nature of things the study is limited to the materials of the accessible crust, although we have in meteorites samples of rocks which must be identical with, or analogous ti, those composing the interior of the earth. The science deals with the modes of occ…