Mystery of the Mega Flood

There is a large terrain called the scablands filled with valleys and hills which looks like it was made by water.  It was a mystery about the scablands and how they were formed, located 200 miles east of Seattle.  There was no evidence of any flowing water.  A geologist, J Harlen Bretz, believed the scablands had come about by a huge flood.  People didn't agree with Bretz and thought what he was talking about was pretty absurd.  However one person, Joseph Thomas Pardee teamed up with Bretz to figure out if he was right.  Padree did find an area in Montana where a lake had been and he started to believe that if a glacier had broken near the scablands then that area would have been able to create valleys and hills.  The big problem here was that the dam was a massive ice berg, and many doubted that it would break.  However, later this whole mystery was later discovered when a similar dam located in Iceland broke.