Question

What phenomenon contributed to the formation of earth's craters?

Answer 1

Volcanic eruptions and non-planetary collisions.

Explanation:

Currently, the only craters we can see (detect) are those caused by collisions with non-planetary objects.

Long story short, billions of years ago, when our planet was a hot ball of molten rock (wow - I am saying this a lot recently), the pressure towards the centre of the planet was very great and volcanic eruptions were the way to relieve that pressure. Particularly violent volcanic eruptions tore parts of the Earth's crust off into mush but we cannot really see them now as firstly, that phase is long over.

The other way for craters to form is with collisions with celestial objects (like asteroids and random moons that float by, caught in our gravity). There are a number of huge craters that have not been eroded completely by our (astronomically speaking) active atmosphere. Do a search for them on Google Images - very interesting.

However, craters formed by both phenomena mentioned above can be observed in other objects in space, and the best example would be our moon.