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Varnished Colorado River gravel on ancient terrace surface

Detailed Description

Linear tracts and small patches of well rounded and varnished pebbles and cobbles mark the traces of ancient channels, bars, and floodplain terraces of the lower Colorado River. Extremely long durations of exposure to the desert environment transform the surfaces of these deposits to flat, and tightly packed pavements of spectacularly discolored and varnished river rocks.


Public Domain.