Rapid incision of the Colorado River in Glen Canyon - insights from channel profiles, local incision rates, and modeling of lithologic controls

Kristen L. Cook, Kelin Whipple, Arjun Heimsath, Thomas C. Hanks

Research output: Contribution to journalArticle

71 Citations (Scopus)

Abstract

The Colorado River system in southern Utah and northern Arizona is continuing to adjust to the baselevel fall responsible for the carving of the Grand Canyon. Estimates of bedrock incision rates in this area vary widely, hinting at the transient state of the Colorado and its tributaries. In conjunction with these data, we use longitudinal profiles of the Colorado and tributaries between Marble Canyon and Cataract Canyon to investigate the incision history of the Colorado in this region. We find that almost all of the tributaries in this region steepen as they enter the Colorado River. The consistent presence of oversteepened reaches with similar elevation drops in the lower section of these channels, and their coincidence within a corridor of high local relief along the Colorado, suggest that the tributaries are steepening in response to an episode of increased incision rate on the mainstem. This analysis makes testable predictions about spatial variations in incision rates; these predictions are consistent with existing rate estimates and can be used to guide further studies. We also present cosmogenic nuclide data from the Henry Mountains of southern Utah. We measured in situ 10Be concentrations on four gravel-covered strath surfaces elevated from 1 m to 110 m above Trachyte Creek. The surfaces yield exposure ages that range from approximately 2·5 ka to 267 ka and suggest incision rates that vary between 350 and 600 m/my. These incision rates are similar to other rates determined within the high-relief corridor. Available data thus support the interpretation that tributaries of the Colorado River upstream of the Grand Canyon are responding to a recent pulse of rapid incision on the Colorado. Numerical modeling of detachment-limited bedrock incision suggests that this incision pulse is likely related to the upstream-dipping lithologic boundary at the northern edge of the Kaibab upwarp.

Original languageEnglish (US)
Pages (from-to)994-1010
Number of pages17
JournalEarth Surface Processes and Landforms
Volume34
Issue number7
DOIs
StatePublished - Jun 2009

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canyon
river
tributary
modeling
bedrock
relief
interpretation
trachyte
history
prediction
rate
marble
river system
gravel
spatial variation
mountain

Keywords

  • Colorado River
  • Cosmogenic nuclides
  • Henry Mountains
  • Quaternary incision

ASJC Scopus subject areas

  • Earth and Planetary Sciences (miscellaneous)
  • Earth-Surface Processes
  • Geography, Planning and Development

Cite this

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title = "Rapid incision of the Colorado River in Glen Canyon - insights from channel profiles, local incision rates, and modeling of lithologic controls",
abstract = "The Colorado River system in southern Utah and northern Arizona is continuing to adjust to the baselevel fall responsible for the carving of the Grand Canyon. Estimates of bedrock incision rates in this area vary widely, hinting at the transient state of the Colorado and its tributaries. In conjunction with these data, we use longitudinal profiles of the Colorado and tributaries between Marble Canyon and Cataract Canyon to investigate the incision history of the Colorado in this region. We find that almost all of the tributaries in this region steepen as they enter the Colorado River. The consistent presence of oversteepened reaches with similar elevation drops in the lower section of these channels, and their coincidence within a corridor of high local relief along the Colorado, suggest that the tributaries are steepening in response to an episode of increased incision rate on the mainstem. This analysis makes testable predictions about spatial variations in incision rates; these predictions are consistent with existing rate estimates and can be used to guide further studies. We also present cosmogenic nuclide data from the Henry Mountains of southern Utah. We measured in situ 10Be concentrations on four gravel-covered strath surfaces elevated from 1 m to 110 m above Trachyte Creek. The surfaces yield exposure ages that range from approximately 2·5 ka to 267 ka and suggest incision rates that vary between 350 and 600 m/my. These incision rates are similar to other rates determined within the high-relief corridor. Available data thus support the interpretation that tributaries of the Colorado River upstream of the Grand Canyon are responding to a recent pulse of rapid incision on the Colorado. Numerical modeling of detachment-limited bedrock incision suggests that this incision pulse is likely related to the upstream-dipping lithologic boundary at the northern edge of the Kaibab upwarp.",
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T1 - Rapid incision of the Colorado River in Glen Canyon - insights from channel profiles, local incision rates, and modeling of lithologic controls

AU - Cook, Kristen L.

AU - Whipple, Kelin

AU - Heimsath, Arjun

AU - Hanks, Thomas C.

PY - 2009/6

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N2 - The Colorado River system in southern Utah and northern Arizona is continuing to adjust to the baselevel fall responsible for the carving of the Grand Canyon. Estimates of bedrock incision rates in this area vary widely, hinting at the transient state of the Colorado and its tributaries. In conjunction with these data, we use longitudinal profiles of the Colorado and tributaries between Marble Canyon and Cataract Canyon to investigate the incision history of the Colorado in this region. We find that almost all of the tributaries in this region steepen as they enter the Colorado River. The consistent presence of oversteepened reaches with similar elevation drops in the lower section of these channels, and their coincidence within a corridor of high local relief along the Colorado, suggest that the tributaries are steepening in response to an episode of increased incision rate on the mainstem. This analysis makes testable predictions about spatial variations in incision rates; these predictions are consistent with existing rate estimates and can be used to guide further studies. We also present cosmogenic nuclide data from the Henry Mountains of southern Utah. We measured in situ 10Be concentrations on four gravel-covered strath surfaces elevated from 1 m to 110 m above Trachyte Creek. The surfaces yield exposure ages that range from approximately 2·5 ka to 267 ka and suggest incision rates that vary between 350 and 600 m/my. These incision rates are similar to other rates determined within the high-relief corridor. Available data thus support the interpretation that tributaries of the Colorado River upstream of the Grand Canyon are responding to a recent pulse of rapid incision on the Colorado. Numerical modeling of detachment-limited bedrock incision suggests that this incision pulse is likely related to the upstream-dipping lithologic boundary at the northern edge of the Kaibab upwarp.

AB - The Colorado River system in southern Utah and northern Arizona is continuing to adjust to the baselevel fall responsible for the carving of the Grand Canyon. Estimates of bedrock incision rates in this area vary widely, hinting at the transient state of the Colorado and its tributaries. In conjunction with these data, we use longitudinal profiles of the Colorado and tributaries between Marble Canyon and Cataract Canyon to investigate the incision history of the Colorado in this region. We find that almost all of the tributaries in this region steepen as they enter the Colorado River. The consistent presence of oversteepened reaches with similar elevation drops in the lower section of these channels, and their coincidence within a corridor of high local relief along the Colorado, suggest that the tributaries are steepening in response to an episode of increased incision rate on the mainstem. This analysis makes testable predictions about spatial variations in incision rates; these predictions are consistent with existing rate estimates and can be used to guide further studies. We also present cosmogenic nuclide data from the Henry Mountains of southern Utah. We measured in situ 10Be concentrations on four gravel-covered strath surfaces elevated from 1 m to 110 m above Trachyte Creek. The surfaces yield exposure ages that range from approximately 2·5 ka to 267 ka and suggest incision rates that vary between 350 and 600 m/my. These incision rates are similar to other rates determined within the high-relief corridor. Available data thus support the interpretation that tributaries of the Colorado River upstream of the Grand Canyon are responding to a recent pulse of rapid incision on the Colorado. Numerical modeling of detachment-limited bedrock incision suggests that this incision pulse is likely related to the upstream-dipping lithologic boundary at the northern edge of the Kaibab upwarp.

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