Click for full image.
Today’s cool image, shown in a rotated, cropped, and reduced version to the right, gives us a close-up look at one of the giant scallops found in the high mid-latitudes of the northern lowland plains of Mars, specifically in Utopia Basin north of the landing sites of both Perseverance and Zhurong. In fact, this particular image is only a few miles north of one of my previous cool images, Giant scallops on Mars, posted in December 2019.
The image was taken on February 3, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). While such scallops are not unusual in the mid-latitudes, their formation process is not well understood. As I noted in the 2019 post, ” scientists believe [pdf] the formation process is related to the sublimation of underground ice.”
According to [one hypothesis] scallop formation should be ongoing at the present time. Sublimation of interstitial ice could induce a collapse of material, initially as a small pit, then growing [away from the equator] because of greater solar heating on [that] side. Nearby scallops would coalesce together as can be seen to have occurred.
This hypothesis is not proven, and today’s cool image raises questions about it. Though the bright material at its center suggests exposed ice, supporting the idea that sublimation of ice near the surface created the scallop, the scallop scarps seem more extended and distinct to the south, not the north as this hypothesis proposes. Sunlight should hit the northern scarps more, which suggests they should retreat more instead of the southern scarp.
The overview map below provides the context.
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