Question

how was the shape of the grand canyon formed?

• tectonic plates moving apart and splitting the colorado plateau into two pieces
• the colorado river carved the canyon
• chemical weathering carved the canyon
• fossil wedging carved the canyon

how did the grand canyon get so wide?

• tectonic plates moving apart and splitting the colorado plateau into two pieces
• the colorado river alone carved the canyon depth and width
• the tributaries that feed into the colorado river made the canyon wide

in a debris flow, what is moving?

• water only
• solid materials only: pieces of rock ranging in size that acts like a river
• water and solid materials: pieces of rock being carried by the flowing water

all rocks are subject to change.

• true
• false

Explanation:

First Question (How was the Grand Canyon formed?):

The Grand Canyon was formed by the Colorado River eroding the rock layers over millions of years. Among the options, "The Colorado River carved the canyon" is the correct reason as the river's flow and erosion (including both water and sediment transport) shaped the canyon. The other options are incorrect: tectonic plates moving apart and splitting the plateau is not the main cause, chemical weathering alone isn't the primary process, and fossil mapping is unrelated to canyon formation.

To widen the Grand Canyon, tributaries feeding into the Colorado River eroded the surrounding areas, increasing the canyon's width. Tectonic plates moving to split the plateau doesn't explain width increase, and the Colorado River alone carving depth/width is more about vertical/initial erosion; tributaries' contribution to lateral erosion (widening) is key.

Debris flow involves the movement of water and solid materials (like rock pieces, soil) together. "Water only" is incorrect as debris flow has solid debris, "Solid materials only" is wrong as water is part of the flow. So the correct option is water and solid materials (pieces of rock) being carried by flowing water.

Answer:

The Colorado River carved the canyon

Second Question (How did the Grand Canyon get so wide?):