THEMIS Image of the Day, June 11, 2019. Today’s VIS image is located on the margin of the Terra Sabaea highlands and the Nilosyrtis Mensae lowlands. The drop off is very steep – about 18,000 ft.
This “edge” circles the northern hemisphere of Mars and is called the crustal dichotomy. The process that created this dichotomy is unknown. In the transition region, the highlands break up into mesas and valleys, like those seen in this image.
The striations in the valley floors suggest that they are filled with glacier ice that flowed at one time.