As time passed, the region would have cooled down considerably and contracted--thus pulling away from its surroundings and forming fractures akin to the cracks that form in mud as it becomes dry--but on a considerably larger scale.
The astronomers found that larger craters, which excavated pits much deeper into the Moon's surface, only increased porosity in the underlying crust. This indicates that these deeper layers have not reached a steady state in porosity, and are not as fractured as the megaregolith.
Were you aware of the fact that the moon has a huge impact on fishing? I used to find this hard to believe, but it's true. And you don't have to be a rocket scientist to understand how the moon and fishing fit together. As a matter of fact, by spending about a half an hour educating yourself can pay huge dividends in not only the amount of fish that you catch, but also the size of those fish. All because of the moon, who would have thought?