I haven’t budged from where I left off over a month ago. I think there have been at least three (somewhat) distinct models from some of the same lines of evidence.
As I recall, Firestone had offered up the theory the earth was hit with a mega cosmic wave(gamma rays, x-rays, whatever) along about the same time period being discussed. Are you aware of any changes in his position? Seems he caught a good deal of flak over it.