It’s not that common to see craters on steep hills, partly because rocks falling downhill can quickly erase such craters. Here, however, a small impact occurred on the sloping wall of a larger crater and is well-preserved .
Dark, blocky ejecta from the smaller crater has flowed downhill (to the west) toward the floor of the larger crater. Understanding the emplacement of such ejecta on steep hills is an area of ongoing research.
Written by: Kirby Runyon (13 June 2017)
More info and image formats at http://hirise.lpl.arizona.edu/ESP_050259_1380
Image: NASA/JPL/University of Arizona