> Types of cave entrances identified in the catalog include lava tube skylights, deep fractures, Atypical Pit Craters (APCs), and other void spaces in karst-sim

> Types of cave entrances identified in the catalog include lava tube skylights, deep fractures, Atypical Pit Craters (APCs), and other void spaces in karst-similar terrains. The cave candidates that they displayed in the image were all in the Tharsis Montes surrounding the major martian volcanos in the most volcanic region of Mars, so I suspect that those ones are largely lava tubes.