Strata of the Grand Canyon

Let’s look at the strata of the Grand Canyon and try to go through the sequence of steps it must’ve gone through according to SG.

As mentioned by brunumb, all of this must’ve originally been underwater. This is a large expanse and the strata is quite deep.

“The Grand Canyon is 277 miles (446 km) long, up to 18 miles (29 km) wide and attains a depth of over a mile (6,093 feet or 1,857 meters).”
https://en.wikipedia.org/wiki/Grand_Canyon

So, every layer that accumulated was underwater, flat, and extended across a very large area. Each layer is reputedly spanning thousands/millions of years. During this entire time, all the layers were flat. Sediment from some remote mountain erosion was able to be deposited relatively evenly across miles. This is done for each layer. For each successive layer, there is little to no erosion, no tectonic activity, no folding, no uplift, Repeat this for several thousand feet of strata. The oldest sedimentary layer is around 1.25 billion years. So, for over a billion years, we have a building up of all the layers, from unknown remote mountains that was able to uniformly deposit layers, with practically no geologic activity occurring during the billion years. Then after all these layers are formed, it is eroded by water activity to form the exposed canyon. I mean, does this even sound reasonable? Why this particular sequence of steps? And why is this sequence of steps found everywhere around the world?