Dionysius crater (17.297°E, 2.766°N) is situated on the western edge of Mare Tranquillitatis (the Sea of Tranquility) and excavates both bright (highland) and dark (mare) materials. Dark banded layers of mare peek out of the eastern wall, where mare material was disturbed by the impact that formed Dionysius crater. Bright talus trails wind downslope through crags and crannies in the dark mare scarps.
Looking closely, the mare appears banded or striated, indicating a non-uniform material. In general, mare are thought to form from large volumes of fluid lavas, much like the Columbia River Basalts in the Pacific Northwest of North America. The stratifications in the lunar mare may represent a series of lava flows in the region.