The smooth, dark maria on the Moon are
A) immense basins that are smooth because they were covered by lava flows after the early heavy bombardment had ended.
B) immense impact basins that are smooth because earlier craters were wiped out by the impact.
C) areas that were still molten at the time of the early heavy bombardment and therefore show no evidence of the impacts.
D) regions that, although as old as the cratered highlands, escaped the early heavy bombardment.

Question

Quizplus · Accepted Answer

The smooth, dark maria on the Moon are immense basins that became smooth because they were filled by basaltic lava flows after the period of heavy bombardment in the Moon's early history. This process covered over the older, more heavily cratered terrain, resulting in the relatively smooth, dark plains we see today.

The Smooth, Dark Maria on the Moon Are