Abstract
Incision rates of the Colorado River are integral to understanding the development of the Colorado Plateau. Here we calculate episodic incision rates of the Colorado River based on absolute ages of two levels of Quaternary deposits adjacent to Glen Canyon, Utah, along the north flank of Navajo Mountain. Minimum surface ages are determined by a combination of cosmogenic radionuclide surface exposure ages, uranium series and soil-development formation times. Bedrock incision rates of the Colorado River between c. 500 ka and c. 250 ka, and c. 250 ka to present are c. 0·4 m ka-1 and c. 0·7 m ka-1, respectively. These rates are more than double the rates reported in the Grand Canyon, suggesting that the Colorado River above Lees Ferry is out of equilibrium with the lower section of the river. We also determine incision rates of two tributaries to the Colorado River. Oak Creek and Bridge Creek flow off Navajo Mountain into Glen Canyon from the southeast. Oak Creek and Bridge Creek both have incision rates of c. 0·6 m ka-1 over the past c. 100 ka at points about 9 km away from the main stem of the Colorado River.
Original language | English (US) |
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Pages (from-to) | 973-984 |
Number of pages | 12 |
Journal | Earth Surface Processes and Landforms |
Volume | 30 |
Issue number | 8 |
DOIs | |
State | Published - Aug 2005 |
Externally published | Yes |
Keywords
- Colorado River
- Episodic Quaternary incision
- Glen Canyon
- Navajo Mountain
ASJC Scopus subject areas
- Geography, Planning and Development
- Earth-Surface Processes
- Earth and Planetary Sciences (miscellaneous)