Edward W. Sawyer 
Atlas of Migmatites [PDF ebook] 

Migmatites are highly heterogeneous rocks found in high-grade metamorphic environments; they are commonly encountered in the continental crust. Until now, many geologists have been deterred from working with migmatites because of their complex appearance and an unhelpful non-genetic nomenclature. In his Atlas of Migmatites, Dr. Edward Sawyer provides genetically based definitions and a system of nomenclature with which it will be possible to describe and map migmatites effectively and to understand how combinations of factors and processes produce a bewildering morphological diversity.