When geologists conclude that the Grand Canyon sequence of rocks was formed through hundreds of millions of years of deposition, mountain building, and erosion, they are basing this conclusion on the principle of which states that .
A) catastrophism; most rock formations were created as a result of supernatural processes
B) catastrophism; a single, large flood was responsible for the creation of the rock sequence
C) uniformitarianism; all geologic processes take immense amounts of time to occur and always occur at the same rate
D) uniformitarianism; the geologic processes that operated in the past are the same as those that operate today, and they occurred in accordance with the same laws of nature that are operating today

D) uniformitarianism; the geologic processes that operated in the past are the same as those that operate today, and they occurred in accordance with the same laws of nature that are operating today

Explanation:

When geologists conclude that the Grand Canyon sequence of rocks was formed through hundreds of millions of years of deposition, mountain building, and erosion, they are basing this conclusion on the principle of uniformitarianism which states that the geologic processes that operated in the past are the same as those that operate today, and they occurred in accordance with the same laws of nature that are operating today.

Uniformitarianism is a theory in geology which states that the changes in the earth's crust during geological history is as a result of actions of uniform and continuous processes, that the geological processes occurring currently are same processes that have been occurring in history and every part of the world and is continuous.