Overview

Abstract

The study of shale—and we use shale as the generally accepted class name for all fine-grained argillaceous sediment, including mud, clay, and mudstone—can be approached from many points of view (Fig. 1.1), but most of the emphasis has generally been placed upon mineralogy and geochemistry, a possible exception being the study of microfauna in Tertiary and Mesozoic shales. As a consequence, much more is known about sandstones and carbonates and even evaporites than shales. As sedimentologists we have long had an interest in shales and are acutely aware of how far their study lags behind that of most other sediments. All too commonly shale has been the “interbedded” and “taken for granted” matrix between lithologies of greater scientific or economic interest, in spite of the fact that shale forms more than 60% of the world’s sediments.

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