http://www.newsweek.com/moon-shrinking-moonquakes-lunar-surface-1423527

In 2010, scientists discovered that our moon had been shrinking as its interior cooled down—and may still be getting smaller. Using images from NASA’s Lunar Reconnaissance Orbiter (LRO), researchers discovered cliffs in the lunar crust that had formed relatively recently, geologically speaking: They could be just 100 million years old.

The findings suggested that these "cliffs," or thrust faults, had formed as a result of tectonic activity related to the moon contracting in size as it cooled.