A lithologic strip log draws the ground as a vertical object. A depth axis runs down one side, deepest at the bottom; beside it a graphic column carries FGDC Section 37 patterns — sandstone as stipple dots, shale as fine horizontal rules — inked flat black on white log stock, with only components at or above 25% abundance drawn, at width proportional to percentage.

The sheet is read next to the physical core: brown rock in 2–3 ft trays, wooden spacer blocks marking runs and core loss, run numbers written three times on every box. Brown is the working line colour because these plates were reproduced as sepia diazo for sixty years, and the tradition kept the colour of its own copies.