The Virgin River and its tributaries run through Zion National Park. This water is the primary agent of erosion that continues to carve and shape Zion.

Though the river is relatively small, it is incredibly steep. The river drops roughly 7,800 feet in the 160 miles it travels.
In the park, the river drops an average of 71 feet every mile. In comparison, the Mississippi River drops about one inch every mile.
This steepness, caused by the uplift of the Colorado Plateau, has given the Virgin River the ability to cut through sandstone and carve canyons.