Question

Covering about 16 percent of the moon's surface, maria are dark, solid, flat areas consisting of what substance?

Answer 1

lava

When you look at the Moon from Earth, you notice dark and light areas. The maria are dark, solid, flat areas of lava. Maria covers around 16% of the Moons surface, mostly on the near side. The maria formed about 3.0 to 3.5 billion years ago, when the Moon was continually bombarded by meteorites   Figure below  . Large meteorites broke through the Moons newly formed surface. This caused magma to flow out and fill the craters. Scientists estimate volcanic activity on the Moon ended about 1.2 billion years ago.