In this 0.25 m/pixel NAC frame we found narrow fractures that extend across the lunar surface, in the mare basalt of Lacus Somniorum. Narrow fractures like these are probably extensional features caused by tensional stress that pulls the rocks apart in opposite directions. Similar fractures have been found before on top of wrinkle ridges. The fractures in today's Featured Image are also associated with a small wrinkle ridge. In the LROC WAC 100 m/pixel context image below, you can see the ridge (white arrow) between two hills of non-mare material. The fractures are located to the east of the ridge (white asterisk). There are a number of other wrinkle ridges in the area as well.
Examine the rest of the narrow fractures in the NAC frame!
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