Erosion has had a huge impact on what the Earth looks like today and what it may look like in the future. Over millions of years, the flowing water of the Colorado River moved rock and sediment from one place to another. Eventually, the river carved out the Grand Canyon. Glaciers also erode the landscape as they creep slowly across the Earth. These enormous masses of ice move at a speed of up to 12 inches per year, picking up and depositing rocks, soil and minerals along the way. Over time, glaciers create valleys, lakes and ravines.
Based on the passage, what is responsible for creating the Grand Canyon?
A
a glacier
B
a lake
C
a ravine
D
a river
