One of the largest canyons on earth is the Blyde River Canyon in South Africe. It is 16 miles long and averages 2,460 feet in depth.
We see multiple parallel layers. So, when they were originally formed, it was all relatively flat and underwater. These layers covers a vast range of land. Then after all these layers were deposited, massive erosion took place. I don’t think any of these statements can be disputed. One questions is the timescale of how fast this sequence of steps occurred. Is it on the order of millions/billions of years? Or was it much faster than that? Also why this sequence? What would cause this? Does SG have any predictive power to explain this sequence?