How Can 10 Million Gallons of Water a Year Suddenly Appear in a Stony Desert?
The answer lies buried in the white and red rocks you can see ahead.
Here about 90 percent of any rain and snow is absorbed by plants or quickly evaporates. Only 10 percent of Pipe Spring’s precipitation soaks into the light-colored rock you see at the top of the cliffs. Water can move easily but slowly through this fine-grained Navajo sandstone.
The red Kayenta mudstone you see in the cliff face blocks water from going deeper into the earth. At the Sevier Fault, a great fracture thousands of feet deep, rocks west of Pipe Spring have slipped down relative to the rocks to the east. Water in the sandstone follows the slope of the land, moving eastward. Groundwater creeps downhill until it is blocked by the impermeable Chinle mudstone formation at the Sevier Fault. The water then moves south in an underground trough created where the rock layers have bent along the faultline. At Winsor Castle, where the porous sandstone has eroded away, the water is released to the surface.