Types of Tectonic Process

Abstract

The fundamentals of structural geology are not dealt with in this book The reader is assumed to be familiar with them to the extent of the ordinary textbooks. See, for example: V.V. Beloussov, Structural Geology. Translated by A. Gurevich, Mir Publishers, Moscow, 1968. Here we shall only touch on its problems in passing, our book being chiefly devoted to general geotectonics, which means that our attention will be mainly focused on the movements of the Earth’s crust that shape tectonic forms rather than on the forms themselves. It must be remembered, however, that ideas about tectonic movements themselves (or diastrophism) come almost exclusively from study of the structural forms that are the end results of these movements. Only by studying the folding of crustal strata can we form an opinion of “folding” tectonic movements. Only by considering the distribution of the thicknesses of the Earth’s crust and the lithological composition of rocks and the broad gentle upwarps and downwarps of strata do we obtain data on vertical (so-called oscillatory) movements of the crust. The history of the uplifts and subsidences of the crust that occurred in past geological periods is also reconstructed from the changes in the outlines of land and sea imprinted in the distribution of regions (a) of the accumulation of marine and continental sediments, and (b) where the sediments of a given age have been eroded away.