THEMIS Image of the Day, April 30, 2014. Triangular shaped deposits at cliff edges are termed alluvial fans. Alluvial fans typically form in arid regions were water flow is limited, so deposits of material are not washed away. Formation of these alluvial fans in the channel of Kasei Valles likely happened after any flow of fluid in the Valles system.
More THEMIS Images of the Day by geological topic.