ripples in the Lunar Mare

[michaellxv]

A question for Lunar geologists.

There have been a number of excellent pics of the moon recently and I have been looking at the ripples in the Mare wondering exactly how they are formed.

Is it multiple layers of lava flow stopping at different places?
Or an impact before the lava set creating waves?
Or something else:question:

[mental4astro]

There are several ways that these 'ripples' may form:

Crushing of the surface from impact shock wave.

Fault lines.

Successive lava flows.

Folding of the crust layers with crust movement.

These are all the same forces that would see the same formations created here on Earth, with the exception of those formed by the effects of weather and water. Moon's been in drought for a while now.