By Prof. A. Johannsen. Vol. 1: Introduction, Textures, Classifications and Glossary. Pp. xxii + 267. (Chicago ... he gives in summary some twenty-five systems of classification of the igneous rocks.

Roughly 1.6 miles from the start, fist-sized globs of rust- and ash-colored rock begin to appear along the route. Look closely and you’ll see the characteristic vesicular texture (holes formed ...