The Geology and Mapping of Granite Batholiths

Book excerpt: This book is mainly about the field geology of granites at all scales from that of a single outcrop to plutons and batholiths. All field geologists work initially at the scale of the outcrop, consequently most of the phenomena treated herein are those which are visible at outcrop scale. However, granites typically occur as plutons and batholiths, some of which are so large as to apparently defy any effort at systematic treatment. Having had the opportunity of mapping two very large and very different batholiths, namely the Coastal Batholith of Peru and the tin granites of Southeast Asia, I have found that it is possible to map large batholiths within a relatively short time, so that the geology of the batholith as a whole can be appreciated. Moreover batholiths are one of the most common modes of granite occurrence, so it makes sense to study them at their natural scale. During my working life I have worked with many geologists from underdevel oped countries and this book is mainly to help them in unravelling the geology of their native batholiths. I have been lucky with my friends and colleagues of many nationalities, and I particularly thank Wallace Pitcher, who took me on as an untried apprentice in Peru, and who, by his kindness and example, showed me how to look at granites properly.