Marisol- From the video, we see that the Grand Canyon used to be covered by an ocean that caused sand, dirt, and sea shells to be deposited at the canyon, this added to the land. Then the ocean dried up. Next, the Colorado river 5-6 million years ago caused weathering of the sides of the canyon becuase it had tons of water mixed with sand and rough rocks, it was like liquid sandpaper. The river caused erosion of the broken peices as it moved them down the canyon and. The Colorado river is what made the canyon deep. At the same time, constant rain and ice weathered the sides of the canyon into sediments and they were then carried downstream by river erosion. This is what made the Grand Canyons walls wide. And that is how the grand canyon was formed.