Petrography Petrography Petrography is a branch of petrology that focuses on detailed descriptions of rocks. Someone who studies petrography is called a petrographer. The mineral content and the textural relationships within the rock are described in detail. The classification of rocks is based on the information acquired during the petrographic analysis. Petrographic descriptions start with the field notes at the outcrop and include macroscopic description of hand specimens. However, the most important tool for the petrographer is the petrographic microscope. The detailed analysis of minerals by optical mineralogy in thin section and the micro-texture and structure are critical to understanding the
A Study of History 23 civilizations identified by Toynbee in vol. Vii. This table does not include what Toynbee terms primitive societies, arrested civilizations, or abortive civilizations. Civilizations are shown in boldface. Toynbee's "Universal Churches" are written in "italic" and are chronologically located between second- and third- generation civilizations, as is described in volume VII. The social scientist Ashley Montagu assembled 29 other historians' articles to form a symposium on Toynbee's "A Study of History", published as The book includes three of Toynbee's own essays: "What I am Trying to Do" (originally published in "International Affairs" vol. 31, 1955); "What the Book is For: