MEGATECTONICS AND MICROTECTONICS

Abstract

TECTONICS is a branch of structural geology concerned with the deformational structure of the earth's crust as a whole and of its major and minor elements. It was Nicolaus Steno who in 1669 laid the foundation of the science of tectonics, but it was not until the beginning of the nineteenth century that tectonics assumed the character of an inductive science. During its earlier stages, tectonics was concerned only with the larger features such as folding, faulting and jointing, but with the advent of the microscope in geology, smaller features of rocks came to be studied. The pioneer of microscopical methods in petrology was H. C. Sorby, whose series of papers piiblished between 1850 and 1860 opened up a new line of research both in the mineral composition and in the texture of rocks. After 1860 the attention of petrologists was concentrated mainly on the study of the composition of rocks, and their textural aspects were treated only from a descriptive point of view. The study of larger features of the earth's crust, however, proceeded with increasing vigour and scope.