A graphic display summarizing the stratigraphy of a particular area. The vertical scale represents geologic time, the horizontal scale represents distance, and the time-range and geographic extent of known stratigraphic units are plotted against these two variables. A range of information, obtained from seismic sections, well log, outcrops, etc., is shown on the chart. This may include lithology, bounding unconformities at the top or bottom of depositional sequences (see baselap; downlap; onlap; toplap), the position of known lithostratigraphic units, facies changes, and the location of wells. See also seismic stratigraphy.