Spectral Subdivision of Limestone Types

In the the writer's previous classification of limestones, rocks were divided into three major families. A more sensitive division can be made into eight groups forming a complete spectrum of textural types, representing deposition in environments of different physical energy. Basis for the classification is (1) relative proportion of allochems and carbonate mud, (2) sorting of allochems, and (3) rounding of allochems. A complete parallel exists between these limestone types and the sequence of textural maturity in sandstones, even to the existence of textural inversions. However, rounding appears to be accomplished best in environments where the energy level is too great for good sorting.