megabreccia

-A new image shows possible "megabreccia" along the center of Mars's Coprates Chasma, a major trough in the Valles Marineris canyon system.

On Earth, breccia is a jumble of broken rocks cemented together by fine-grained material that is found around volcanoes and impact craters. Megabreccia is a larger version of this feature--large enough that it can be identified in images taken by the Mars-orbiting HiRISE camera.