Analysis of Sedimentary Structures

Abstract

Sedimentary structures are generally studied in the field, where sketches or photographs are taken to record characteristics and for later analysis, and where a compass and clinometer are utilized to quantitatively measure the three-dimensional attitude of the elements composing the structures (see Chapter 3 and PS Chapter 4). Devices such as the disk shown in Fig. 6–1 can prove convenient in the field for measuring the strike and dip of cross-bedding that is not exposed along the bed surfaces. Video cameras are utilized increasingly in both the laboratory and the field to obtain quantitative as well as qualitative data on the development of sedimentary structures. Peels (see Chapter 3) and surface replicas (see below) are also obtained in the field to permit laboratory studies of small-scale structures. Obscure small-scale internal structures can be artificially enhanced or must be studied in the laboratory utilizing special photographic equipment, X-ray radiography, or stains (e.g., Chapter 8). In the case of laboratory specimens, if any directional data are desired, it is essential that their spatial orientation be recorded when they are collected.