ICR article image.
I’ve also heard that the Grand Canyon was formed very quickly when a debris dam somewhere in what is now MT formed and filled with melting water at the end of the Ice Age. When that dam broke, a gazillion gallons of water rush out and very quickly cut what is now the Grand Canyon. If true, there would be no talus accumulation at the bottom. As least it’s as consistent as the theory posed here.
Mt Saint Helens was an example of very fast creation of a massive canyon: http://www.icr.org/research/index/researchp_sa_r04/
That ICR article has to rate as one of the stupidest of their stupid articles. Every one of their examples of an alleged mystery talus slope is actually an obvious example of riverine, glacial, and/or marine erosion of the talus. There is no excuse for such obvious dishonesty on their part.