I don't think it's Biblically "provable" at all. I do think that the Scriptures are decidedly consistent with it, and moreover....given the way Genesis is quoted so extensively in other books......there was MORE than ample opportunity to merely say "Moses said". However, it doesn't. I think that if that theory is true, than it is at least
implied by the Scriptures, by I don't think it's "provable" at all.
If studied...I think the explanation we are proposing is by far the most probable, and also least fancifull and fits nicely with what we DO know. It maintains a high view of Scriptural innerancy. Some theories extant do more to deny Genesis' legitimacy than support it and they must be made aware of.
From my perspective, this explanation answers the most questions while posing the fewest problems, and it also seems very consistent with Scripture while also appealing to Divine Revelation without forcing us to appeal to rather fanciful forms of inspiration (like God spoke every word of it to Moses at Sinai or something)....Granted, that's possible of course, but why appeal to MORE DIRECT Divine influence than is necessary? God's Providence in "preserving" the accounts is perfectly sufficient than to suggest that God would have had to practically hand the book to him or dictate it word-for-word 2000-years later (in many cases). No problem believing God preserved some first-hand accounts from Adam, Seth, Enoch etc...and Noah was savvy enough to take them on the ark with him.
BTW: Kudos for teaching through Genesis!! I am a "Genesis-o-phile" for my part. I found Henry Morris' book (although I disagree with him on some points) to be
INCREDIBLE!
http://www.amazon.com/dp/0801072824/?tag=baptis04-20
Even the points of contention one might disagree with him on such as
1.) Identity of the "Nephilim" and the "Sons of God" etc....in Genesis 5
or
2.) The identity of Melchizedek
He does a remarkable job of explaining the arguments from all sides quite fairly
It's VERY worth the read....I use it extensively, and have read through it about three times. I consult it often if teaching Genesis.
He also goes in good depth as to the Theory of Mosaic authorship of the Pentateuch vs. the compilation/editting of Genesis that I am proposing. He is a proponent of the Theory as well.