The fossils documented evolution's march through time, with simple creatures at the bottom and complex ones at the top. The Colorado River took 70 million years to erode the Canyon. Now many geologists who study the Canyon are talking about catastrophic deposition. They are postulating runaway erosion within the last one million years. Keep in mind, these events happened in the unobserved past.
Scientists study the results of past processes in the present, and try to reconstruct the past.
The best we can do is to identify our view of history, interpret the evidence within that view, and see which view does the best job. In addition, when we do, I am convinced the Biblical view comes out on top. Let us take a brief look at some of the evidence in Grand Canyon. Evidence of underwater turbidity currents is found in the Tapeats Sandstone, the Redwall Limstone, and others. The Supai Formation has traditionally been interpreted as a delta deposit, but has laterally extensive thin members, unlike modern deltas.