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Small Crater in Oceanus Procellarum
Unnamed 740 m diameter crater with bouldery walls › View larger image
This unnamed 740 m diameter crater has bouldery walls and is morphologically similar to many <1 km diameter craters in the mare. Image width is 847 m, LROC NAC M127328861L [NASA/GSFC/Arizona State University].

The LROC NAC has imaged thousands of blocky craters similar to this example found in Oceanus Procellarum. The numerous boulders may be fragments of bedrock, regolith breccias formed by the impact itself, or a combination of both. Since a crater depth of excavation is roughly one tenth its diameter, this small crater has probably distributed material from about 75 meters depth around its rim. Usually, ejecta material on the rim comes from the deepest part of the crater, and ejecta farther away from the crater comes from shallower depths. As you look at these boulders, you are witnessing a history of the emplacement of this mare.

Oceanus Procellarum mare basalts › View larger image
The vast Oceanus Procellarum mare basalts are observed in this portion of LROC Wide Angle Camera monochrome M117895651M. Prominent across the scene are wrinkle ridges and secondary crater clusters. The arrow points to the blocky crater in the opening image [NASA/GSFC/Arizona State University].

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