Lunar Reconnaissance Orbiter Camera

Tendrils in Reiner Crater

These elongate flows formed during their race towards the floor of Reiner crater. Boulders have piled up at the base of the flows. Are the flows impact melt, or something else? Downslope is to the upper left. LROC NAC M135548391LE, image width is 500 m [NASA/GSFC/Arizona State University].

Reiner crater, located at 6.9°N, 305.0°E, in Oceanus Procellarum, is Eratosthenian in age because it does not have a visible, high-reflectance ejecta ray system like Copernicus or Tycho craters. Today's Featured Image focuses on the southern wall of Reiner crater. The flows emplaced along the crater wall are reminiscent of some impact melt features seen on the Moon. They are elongate, slightly lobate, and have many boulders that could have weathered out of them. And they do appear to have flowed downwards into the crater, solidifying on the wall before reaching the crater floor. But are the flows impact melt?

Arrows point to incisions cut into the crater wall by the flows. LROC NAC M135548391LE, image width is 250 [NASA/GSFC/Arizona State University].

The elongate morphology of these flows is also similar to that of a dry debris flow. Impact melt would only have the chance to flow downhill once before solidifying, but the flows appear to have been deposited successively during multiple flow periods. Furthermore, the flows also cut through loose material on the crater wall, indicating that the flows formed more recently. These relationships are perhaps more consistent with dry debris flows, than impact melt flows.

Can you find more flows in the full NAC frame?

Related Posts: Dry debris or liquid melt?

Splash and flow

Rootless impact melt

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