Different regions on Mars appear to have low-albedo intracrater deposits that have distinct regional thermophysical and/or aeolian dune characteristics. Thermal inertia derived from a carefully selected set of Viking infrared thermal mapper observations of the dark features obtained in 1977--1978 supports this conclusion. The observed similarities and differences among dark intracrater features on Mars is probably a function of the combined influences of sand availability and regional wind conditons.