Unaweep Canyon in the Rocky Mountains is the site of a deep gorge that reveals ancient landscapes and sediments. The inset image is of a "dropstone" from an eons-old glacier. (Credit: Gerilyn Soreghan, courtesy NSF)
Unaweep Canyon in the Rocky Mountains is the site of a deep gorge that reveals ancient landscapes and sediments. The inset image is of a "dropstone" from an eons-old glacier. (Credit: Gerilyn Soreghan, courtesy NSF)
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One interpretation holds that in ancient times, the Dolores River flowed through Unaweep Canyon and into the Gunnison River south of present day Grand Junction, Colorado. A second interpretation is that the Gunnison River itself once flowed through the canyon (Kaplan 2005). In either case as the uplift of the Uncompahgre Plateau between 5 and 15 million years ago resulted in the course change of the river involved and left the canyon without a river. A third, controversial hypothesis holds that the steep sides of the canyon in places indicates the valley was glaciated during the Late Paleozoic (Soreghan, G.S. 2004) or Pleistocene. However, seismic studies indicate that the flat valley floor is a V-shaped valley that was filled by tallus and alluvial fill (Oesleby 2005).