Thursday, March 10, 2011

LROC: Boulders of Dorsum Buckland

Two arrows point to a likely outcrop of bedrock from the wrinkle ridge Dorsum Buckland, a nearside landmark in southern Mare Serenitatis. Frame from LROC Narrow Angle Camera observation M109141090L, LRO orbit 1218, October 2, 2009; image resolution 0.5 meters/pixel, incidence 21° View the full Featured Image HERE [NASA/GSFC/Arizona State University].

Sarah Braden
LROC News System

Today's image is from a small section of the 396 km long wrinkle ridge Dorsum Buckland, which is named after William Buckland, an English geologist who wrote the first full account of a fossil dinosaur! The boulders you see here are on top of the ridge. There are other areas on the long ridge that have similar blocks, but at this spot you can see what might be bedrock eroding out of the ridge as well (white arrows). Wrinkle ridges in the mare form due to compressional stresses probably caused by the weight of many layers of extruded basalts. The boulders may have eroded out of the fractured basalt that forms the ridge. Think about this: If the boulders and the ridge are made from the same material, then why do the boulders have a higher albedo? Or do they boulders have a more complicated origin? Certainly the darker outcrop and the brighter boulders would be easy to sample by future lunar explorers! We may have to wait until then to know for certain.

LROC Wide Angle Camera 100 meter/pixel monochrome mosaic of the vicinity of Dorsum Buckland (outlined in white lines); arrow points to the location of LROC Featured Image, March 9, 2011. View the full-sized context image HERE [NASA/GSFC/Arizona State University].

Another portion of the Dorsum Buckland wrinkle ridge system, further west of the area highlighted in the LROC Featured Image, north of Sulpicius Gallus and south of the Aratus C formation. Wrinkle ridges stand out even in small telescopes, at local sunrise and sunset when even the lowest profile features cast long shadows., making them stand out from the smooth low Serenitatis basin floor. They are often impossible to see in full daylight. LROC WAC monochrome (689nm) observation M116241995ME, LRO orbit 2264, December 23, 2009; resolution 63.4 meters/pixel, solar incidence angle is 83.15, or less than seven degrees above the eastern horizon, soon after local sunrise [NASA/GSFC/Arizona State University].

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