Wednesday, July 2, 2014
Seeing Actual Daylight at Emerald Pools in Zion National Park
Those night hikes are among my most treasured memories. The stars, framed by the high canyon walls, would sparkle. Some years we watched the full moon rise over the cliffs. During a few memorable years we experienced lightning storms, the booms of thunder reverberating across the canyon walls. At night, the Emerald Pools echoed with the surprisingly loud call of frogs, and in the coolness we could smell the moisture in the air, a treat in the desert environment. And one year, a slab of rock three feet across fell from the top of the alcove, landing just a few feet from some of our students.
The water is coming from the Navajo Sandstone, one of the most unique and scenic formations on the Colorado Plateau. The sandstone is porous, and groundwater migrates downwards through thousands of feet of rock. When the water encounters an impermeable layer, perhaps a lens of limestone, it moves sideways. If the impermeable rock is exposed in a canyon wall, the water will flow as springs. That's where all the water in this side canyon is coming from. You can see the springs in the cliff above the pool in the picture below.