Rough highlands and smooth maria on the Moon

Rough highlands and smooth maria on the Moon

Fig. 5.10b . Lunar volcanism is seen frozen into place in this Apollo 15 image of Mare Imbrium, the Sea of Rains. The oblique perspective enhances individual lava flows and the relief of lunar maria ridges. The lunar maria contain relatively few craters when compared with the lunar highlands. The maria formed a secondary crust on the Moon, when lava filled the large impact basins over a period of several hundred million years ending around 3.2 billion years ago. The fluid spread rapidly, creating thin, extensive sheets rather than piling up to form volcanoes. (Courtesy of NASA.)

Copyright 2010, Professor Kenneth R. Lang, Tufts University