Carbonate facies can be described in a concise format that reads like an algebraic equation:

CARBONATE FACIES = (LITHIC DESCRIPTOR) (COMPOSITION) (TEXTURE) ± REMARK.

Lithic descriptors are portrayed by symbols for sedimentary structures, admixtures of argillaceous or arenaceous material, diagenetic features, and/or porosity. The second term, composition, generally used for describing the sand-size fraction of the rock, is represented by symbols designed to look like the grains themselves. Compositional symbols that appear in the equation should include only common rock-forming particle types, listed in order of decreasing abundance. The third term of the equation, texture, consists of a one-letter or two-letter abbreviation for the textural terms of Dunham or of Embray and Klovan. The fourth term of the descriptive equation is optional and allows a qualifying remark, using a minimum of appropriate symbols. Thus, a limestone that is cross-stratifie and consists of 75% ooids and 25% carbonate cement is written as X^ThgrG.

Advantages of this shorthand system are (1) it is graphic and can be used to expedite routine sample logging and digital data recording; (2) it is useful in maps and cross sections to illustrate facies patterns in carbonate rocks, (3) it provides an international shorthand that transcends language barriers, and (4) it is both descriptive and genetic and has important implications for porosity prediction, and is thus an aid in the search for stratigraphic traps.

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