Figure 10-7: R I V U X G
The Near and Far Sides of the Moon The iron-rich darker maria are a younger surface made from ancient lava flows and are 2 to 5 km below the average surface elevation. The cratered highlands are an older surface several kilometers above the average elevation. The South Pole—Aitken Basin reaches depths of 12 km, but was never filled in by darker lava flows. These images were made by the Lunar Reconnaissance Orbiter.

(a: NASA/GSFC/Arizona State Univ./Lunar Reconnaissance Orbiter; b: NASA)