THEMIS: Big impacts and little in Terra Cimmeria

Terra Cimmeria craters (THEMIS_IOTD_20190313)THEMIS Image of the Day, March 13, 2019. This VIS image contains three craters. There is a quarter of the largest crater in the top half of the image, half of a smaller crater at the very top, and the full crater in the lower half of the image.

Investigating the relative ages of each crater indicates the largest crater formed first followed at some point by the smaller craters – the half-crater at the top occurs on top of the big crater as does the ejecta from the bottom crater.

Because the visible ejecta does not reach the smaller crater at the top it is difficult to determine the relative ages of the two smaller craters. Both have similar floor morphology, but different rim morphology. The crater in the bottom of the image has a very complex rim, including both rim gullies (top side) and ridge and spur eroded features (bottom side).

These differences may be related to the different materials of the largest crater. One crater impacted into the floor and the other into the ejecta blanket of the largest crater. Near surface morphology as well as deeper materials can modify the pressure wave created by impact. These craters are located in Terra Cimmeria.

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