This paper is a discussion of methods of collecting and presenting sedimentological field data. A new method of plotting sedimentological data is described which produces a continuous field sketch of the section. These sections consist of a column showing the rock type, to the side of which is added a vertical histogram of grain-size. Within the spaces formed by the histograms, sedimentary structures are shown symbolically. The nature of the basal contact of each bed is also indicated. From date thus recorded, frequency histograms of bed base types and diagrams showing the frequency of occurrence of sedimentary structures within various lithologies can be prepared. On a diagram termed the 'facies profile', a section or group of sections of similar facies are drawn using the conventions already described. However, instead of presenting the beds in the sequence in which they occur in the field, they are grouped vertically according to lithology. All the limestone beds are grouped together, all the shales, and so on. Within the various lithologies beds are grouped according to grain-size and sedimentary structures. Facies profile diagrams contain a wealth of quantitative data in a readily comprehensible form. Such diagrams summarize the sedimentological characters of facies in a quantitative manner. Objective comparisons can be made of strata of similar or dissimilar ages, areas, or environments. These graphic methods of data presentation have been applied in a quantitative comparative study of Miocene and Oligocene shoreline sediments of the Sirte basin, Libya.

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