Expert: Courtney Seligman - 3/30/2009

Question



                                  dear Courtney Seligman,

could you tell me if the idea of the cleavage of the Moon (allegedly occured thousands years ago) in two halves is confirmed by scientists?

Some people claim it is. Their evidences are the fact that theories on the origins of lunar rilles aren't 100% certain, permitting these people to think that these rilles do make sense with that story of moon cleavage.


what is yor opinion about this?


                               Yours sincerely

Answer
Lunar rilles were formed by lava tubes, during the formation of the lunar maria, 3.2 to 3.9 billion years ago. When lavas flow onto the surface of a 'world', they form a 'fusion' crust (that is, a solid crust, on top of a liquid substratum), as a result of heat radiating into space. The crust above can be quite thick, even though lava is still flowing below (the same thing happens all the time, e.g., on Hawaii).

It is quite common, at the end of lava production, for lava to flow completely out of the underground channel, leaving a lava tube. Such tubes/caves are common in Oregon and Washington, as a result of lava flows millions of years ago, and in places such as Hawaii, where lava flows still occur. After some time, the tops of the tubes collapse, leaving meandering 'valleys'. That's what the rilles on the Moon are, the collapse being caused not by erosion by wind and water, but by meteoroid bombardment.

All known evidence of lunar conditions indicate that save for occasional impacts, nothing of any great geological interest has occurred on the Moon in more than 3 billion years. Occasionally nonsense such as the cleavage theory you refer to is put forth by individuals who do not understand the basic geology or astronomy, or refuse to accept it for religious reasons (they do not want to admit that 'Creation' was more than a few thousand years ago). But all such 'theories' are nothing but rubbish, and not worth wasting your time on.

Courtney Seligman