The maria's on the moon were formed by meteors slamming into it.
Maria (singular: mare) were formed by flows of molten rock. As the Moon has not had volcanoes for millions of years, the age of the maria are dated from at least 1 billion (1 x 109) years ago and the...
Meteoroids Impacts.
the Maria's in the moon are formed by volcanic erosion
If you have a good imagination there is a shape on the full Moon which looks like Mary and child.