On the Moon, small topographic highs often covered by boulders are commonly seen in LROC NAC images. Today's Featured Image shows an example of boulders atop a wrinkle ridge.
In two areas of the image high reflectance boulders are on the top of the ridge. The sinuous line to the right of these boulder clusters is the eastern edge of the wrinkle ridge.
Why are there two distinct patches of boulders? The ridge as a whole has numerous boulder patches just like these. How did they form? Were they thrown there by some distant impact event? Are they eroding out of the wrinkle ridge? Has everything nearby been covered by a resurfacing event leaving just a few high patches of bright boulders? We may not know until astronauts visit one of these occurrences and carefully investigate the geology and collect samples!
You should check the whole view of this boulder covered wrinkle ridge by opening the full LROC NAC frame!
Posted by Hiroyuki Sato on April 10, 2011 09:10.