Rock Fractography

Abstract

Woodworth (1895, 1896) set the stage for the science of fractography by astute observations of the morphology of joints in geologic exposures. He also noted the essential morphologic similarities between fracture markings in glass samples and rock outcrops. No one who has worked with glass as an industrial material can fail to be fascinated by its intriguing geometries and lustrous fracture features, so that the interest of the early glass experimentalists in fracture markings was no more than natural (e. g. De Freminville 1907, 1914; Preston 1926,1931, Chap. 2). Rock fracture, by comparison, is drab and lacklustre, and it is therefore not surprising that only very few geologists were attracted to the subject of fracture morphologies on rock exposures during the long period that elapsed between the studies of Woodworth (1896) and those of Hodgson (1961 a, b) (see below). The systematic description of fracture markings in rocks begins with the trail-blazing investigations of Woodworth, followed by the elaboration on those studies by later observers. The present chapter deals mainly with fractography of sedimentary rocks, and only to a limited extent with fracture morphology of igneous rocks.