Hebes Chasma is an almost 8 km deep basin on Mars, stretching 315 km in an east-west direction and 125 km from north to south.
Video: "Flight over Hebes Chasma" from 2008 [4:36 min]
Copyright: ESA/DLR/FU Berlin (G. Neukum)
Hebes Chasma is located north of the vast Valles Marineris canyon. As for Valles Marineris, scientists suspect the origins of Hebes Chasma in the emergence of the Tharsis volcanic region (see also press releases of 2008 and 2013). Scarp slopes rise almost 8000 m into the skies and a mesa, or flat-topped mountain in the centre stretches over 100 km in length and between 10 and 20 km in width. The 8000-meters flat-topped mountain is made up of numerous strata of different rocks, as can be seen clearly in the banded and layered flanks. These are sediment layers, most likely deposited by flowing or standing water.
Link to release in press archive (in German): Hebes Chasma (May 29, 2008)