Sunset over the Unkar Delta
This magnificent photo captures rays of light passing over the Grand Canyon near the point where the Colorado River takes a wide bend to the left. In the foreground ridge you can spot several of the dominant Paleozoic aged units that make up the upper portion of the Canyon Walls, including the prominent Redwall Limestone. The flat area at the center of the frame, near where you can see the Colorado River, is the Unkar Delta. Prior to human involvement, much of the sediment carried by the Colorado River flowed all the way down the river from its origin point in Colorado, but today the Glen Canyon Dam blocks much of that sediment upstream. Unkar Creek is one of several small river channels off to the side of the Canyon that still delivers sediment into the Grand Canyon itself. Unkar Creek has built a delta, a pile of sediment along the flat bend in the river. The river channels that deliver sediment to the Canyon are often associated with rapids, as those channels also deliver boulders that the Colorado waters must cross over or around.
Archaeological Records show that the Unkar Delta was one of the areas of the Canyon inhabited by ancestral peoples over a thousand years ago.
-JBB
Image credit: https://flic.kr/p/KBMLJn
Reference: https://www.nps.gov/grca/planyourvisit/upload/Unkar-Delta-95bro.pdf http://grandcanyon.ucdavis.edu/unkar-delta.html
