Mile 24.5, 24.5-Mile Canyon, Upstream View from River Left (Stake 1414)
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14 July 1889
Franklin Nims took this image “from [a] marble pier,” a large outcrops of Redwall Limestone at the mouth of 24.5 Mile Canyon. This view up 24.5 Mile Canyon shows coarse boulder deposits characteristic of Colorado River tributaries, which episodically produce large debris flows. A relatively white deposit of boulders at the center of the image appears to be the result of a debris flow that did not reach the Colorado River. Most of the shrubs in the view are Mormon tea.
Photo credit: Franklin A. Nims, 57-RS-306, courtesy of The National Archives
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20 January 1990
Changes in the foreground of this view made matching Nims’ view difficult, and the camera station is slightly off. The debris-flow deposit new in 1890 has been eroded away, and the canyon bed has scoured down 2-3 meters, probably during a streamflow flood in this relatively large canyon. While many of the individual boulders are still present, others are gone and others have been added. Some of the Mormon tea persist, and beavertail pricklypear is now growing in the right foreground.
Photo credit: Ralph Hopkins
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16 September 2010
This view matches the 1990 photograph. The boulders in the wash appear to be mostly unchanged in the two decades between matches, while the shrubs—mostly Mormon tea—have increased in size and number. The number of beavertail pricklypear in the foreground has increased, particularly in the left foreground.
Photo credit: John Mortimer
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