How is limestone containing appreciable amounts of clay represented on a lithologic log?

When representing limestone that contains appreciable amounts of clay on a lithologic log, the method involves modifying the existing symbol for limestone. This is achieved by adding a short dash within each box that represents the limestone section of the log. This notation visually indicates that the limestone is not pure and contains a significant amount of clay, which can influence the physical and chemical properties of the rock.

Using a short dash effectively communicates to anyone interpreting the log that this particular limestone sample has distinct characteristics compared to standard limestone, which is typically represented without any modifications. This kind of notation is essential for geologists and engineers as it provides clarity on the composition of the material, which can impact decisions related to construction, resource extraction, or environmental assessments.

In contrast, the other methods outlined do not accurately capture the specifics of limestone with clay content. For instance, using a double box symbol or placing an additional box on top would not convey the intended modification of the limestone's composition, which is crucial for proper interpretation of the geological data.