Book contents
- Frontmatter
- Contents
- List of contributors
- 1 Overview of megaflooding: Earth and Mars
- 2 Channel-scale erosional bedforms in bedrock and in loose granular material: character, processes and implications
- 3 A review of open-channel megaflood depositional landforms on Earth and Mars
- 4 Jökulhlaups in Iceland: sources, release and drainage
- 5 Channeled Scabland morphology
- 6 The morphology and sedimentology of landforms created by subglacial megafloods
- 7 Proglacial megaflooding along the margins of the Laurentide Ice Sheet
- 8 Floods from natural rock-material dams
- 9 Surface morphology and origin of outflow channels in the Valles Marineris region
- 10 Floods from fossae: a review of Amazonian-aged extensional–tectonic megaflood channels on Mars
- 11 Large basin overflow floods on Mars
- 12 Criteria for identifying jökulhlaup deposits in the sedimentary record
- 13 Megaflood sedimentary valley fill: Altai Mountains, Siberia
- 14 Modelling of subaerial jökulhlaups in Iceland
- 15 Jökulhlaups from Kverkfjöll volcano, Iceland: modelling transient hydraulic phenomena
- 16 Dynamics of fluid flow in Martian outflow channels
- Index
- Plate section
- References
5 - Channeled Scabland morphology
Published online by Cambridge University Press: 04 May 2010
- Frontmatter
- Contents
- List of contributors
- 1 Overview of megaflooding: Earth and Mars
- 2 Channel-scale erosional bedforms in bedrock and in loose granular material: character, processes and implications
- 3 A review of open-channel megaflood depositional landforms on Earth and Mars
- 4 Jökulhlaups in Iceland: sources, release and drainage
- 5 Channeled Scabland morphology
- 6 The morphology and sedimentology of landforms created by subglacial megafloods
- 7 Proglacial megaflooding along the margins of the Laurentide Ice Sheet
- 8 Floods from natural rock-material dams
- 9 Surface morphology and origin of outflow channels in the Valles Marineris region
- 10 Floods from fossae: a review of Amazonian-aged extensional–tectonic megaflood channels on Mars
- 11 Large basin overflow floods on Mars
- 12 Criteria for identifying jökulhlaup deposits in the sedimentary record
- 13 Megaflood sedimentary valley fill: Altai Mountains, Siberia
- 14 Modelling of subaerial jökulhlaups in Iceland
- 15 Jökulhlaups from Kverkfjöll volcano, Iceland: modelling transient hydraulic phenomena
- 16 Dynamics of fluid flow in Martian outflow channels
- Index
- Plate section
- References
Summary
Summary
The Channeled Scabland comprises a regional anastomosing complex of overfit stream channels that were eroded by Pleistocene megaflooding into the basalt bedrock and overlying sediments of the Columbia Plateau and Columbia Basin regions of eastern Washington State, USA. Immense fan complexes were emplaced where sediment-charged water entered structural basins. The cataclysmic flooding produced macroforms eroded into the rock (coulees and trenched spur buttes) and sediment (streamlined hills and islands). Several types of depositional bars also are scaled to the channel widths. The erosional mesoforms (scaled to flow depth) include longitudinal grooves, butte-and-basin scabland, potholes, inner channels and cataracts. These make up an erosional sequence that is scaled to levels of velocity, power per unit area and depths achieved by the cataclysmic flooding. Giant current ‘ripples’ (dunes) developed in the coarse gravel bedload, and large-scale scour marks were formed around various flow obstacles, including rock buttes and very large boulders.
Introduction
The Channeled Scabland region (Figure 5.1) is that portion of the basaltic Columbia Plateau and Columbia Basin that was subjected to periodic cataclysmic flooding during the late Pleistocene, resulting in a distinctive suite of flood-related landforms. Bretz (1923a, pp. 577–578) defined ‘scablands’ as ‘lowlands diversified by a multiplicity of irregular and commonly anastomosing channels and rock basins eroded into basalt…’ The term was in local use in reference to chaotically eroded tracts of bare basalt which occur in relatively large channels that the floods cut through the loess cover on the plateau.
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- Chapter
- Information
- Megaflooding on Earth and Mars , pp. 65 - 77Publisher: Cambridge University PressPrint publication year: 2009
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