Preface to Part I
At present many geologists in the United States are interested in some investigations of rock structure that have been developing in Austria and Germany over a period of about twenty-five years. Sander, of Innsbruck, who is the pioneer in this approach to the study of rock constitution, published, in 1930, an exhaustive treatise on the subject, the Gefügekunde der Gesteine. Unfortunately this book, being written in German and being by virtue of its subject matter somewhat difficult reading, has not become widely known by English-speaking geologists.
I became interested in Gefügekunde (structural petrology) about ten years ago, because I was then realizing that I had practically reached a blank wall after struggling for some thirty years with the structural intricacies of metamorphic rocks in the Appalachian Mountains and the Piedmont Province. No field observations seemed to furnish conclusive evidence of structure. Intensive microscopic study of the highly metamorphosed rocks that make up so much of the Atlantic slope added much information about the composition of the rocks, but did not afford a real key to the problem of their history and structure. In fact, the interpretation of geologic structure in this area seemed to resolve itself into a matter of more or less well-justified speculation based upon what poor stratigraphic evidence could be extracted from a terrane of crystalline schists.
At that time a new point of approach to various structural problems appeared to me on reading a paper by Sander in Tschermak’s Mitteilungen. 1 The fundamental . . .