Channeled scabland morphology

Research output: Chapter in Book/Report/Conference proceedingChapter

17 Scopus citations

Abstract

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.

Original languageEnglish (US)
Title of host publicationMegaflooding on Earth and Mars
PublisherCambridge University Press
Pages65-77
Number of pages13
ISBN (Electronic)9780511635632
ISBN (Print)9780521868525
DOIs
StatePublished - Jan 1 2009

ASJC Scopus subject areas

  • Earth and Planetary Sciences(all)

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    Baker, V. R. (2009). Channeled scabland morphology. In Megaflooding on Earth and Mars (pp. 65-77). Cambridge University Press. https://doi.org/10.1017/CBO9780511635632.005