Oscartheduck,
that's a very very good point you get to our attention here. The WTBTS used that kind of teaching many times in their litterature. When they cannot show for sure from which source they take that "direct evidence", they use a endoctrinal technique that is called "straw man" evidence. That comes clear when you seek in profane book from scientists that some statements like that one can be really contradictory of actual archeologic knowledge. And for the one about the flood, there is no evidence yet discovered to confirm that the flood ever occured.