Course of Columbia River in southern central Washington

Warren, Charles Reynolds

doi:10.2475/ajs.239.3.209

Cited by 6 publications

(1 citation statement)

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“…Observations from the structural relations of the Ringold Formation in and near the reservation and those cited at the Potholes Dam agree with Warren's (1941) conclusion that the Ringold Formation was deposited contemporaneously with the uplift and deformation that produced the mountainous ridges of the region. In view of the middle or late Pleistocene age of the Ringold Formation derived by Strand and Hough (1952), the evidence cited above now indicates that the tectonic deformation of the region, with which the deposition of the Ringold coincided and closely followed, is considerably younger (by one million or half a million years) than had been previously supposed.…”

Section: Relations Of the Ringold Formation To The Deformation Of The...supporting

confidence: 69%

Geology and ground-water characteristics of the Hanford Reservation of the U.S. Atomic Energy Commission, Washington

Newcomb¹,

Strand²,

Frank³

1972

Professional Paper

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Section: Relations Of the Ringold Formation To The Deformation Of The...supporting

confidence: 69%

Geology and ground-water characteristics of the Hanford Reservation of the U.S. Atomic Energy Commission, Washington

Newcomb¹,

Strand²,

Frank³

1972

Professional Paper

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Flow directions in Columbia River Basalt flows and paleocurrents of interbedded sedimentary rocks, South-Central Washington

Schmincke

1967

Geol Rundsch

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Upper Grand Coulee: New views of a channeled scabland megafloods enigma

Waitt

Atwater

Lehnigk

et al. 2021

From Terranes to Terrains: Geologic Field Guides on the Construction and Destruction of the Pacific Northwest

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New findings about old puzzles occasion rethinking of the Grand Coulee, greatest of the scabland channels. Those puzzles begin with antecedents of current upper Grand Coulee. By a recent interpretation, the upper coulee exploited the former high-level valley of a preflood trunk stream that had drained to the southwest beside and across Coulee anticline or monocline. In any case, a constriction and sharp bend in nearby Columbia valley steered Missoula floods this direction. Completion of upper Grand Coulee by megaflood erosion captured flood drainage that would otherwise have continued to enlarge Moses Coulee. Upstream in the Sanpoil valley, deposits and shorelines of last-glacial Lake Columbia varied with the lake’s Grand Coulee outlet while also recording scores of Missoula floods. The Sanpoil evidence implies that upper Grand Coulee had approached its present intake depth early the last glaciation at latest, or more simply during a prior glaciation. An upper part of the Sanpoil section provides varve counts between the last tens of Missoula floods in a stratigraphic sequence that may now be linked to flood rhythmites of southern Washington by a set-S tephra from Mount St. Helens. On the floor of upper Grand Coulee itself, recently found striated rock and lodgement till confirm the long-held view, which Bretz and Flint had shared, that cutting of upper Grand Coulee preceded its last-glacial occupation by the Okanogan ice lobe. A dozen or more late Missoula floods registered as sand and silt in the lee of Steamboat Rock. Some of this field evidence about upper Grand Coulee may conflict with results of recent two-dimensional simulations for a maximum Lake Missoula. In these simulations only a barrier high above the present coulee intake enables floods to approach high-water marks near Wenatchee that predate stable blockage of Columbia valley by the Okanogan lobe. Above the walls of upper Grand Coulee, scabland limits provide high-water targets for two-dimensional simulations of watery floods. The recent models sharpen focus on water sources, prior coulee incision, and coulee’s occupation by the Okanogan ice lobe. Field reappraisal continues downstream from Grand Coulee on Ephrata fan. There, some of the floods exiting lower Grand Coulee had bulked up with fine sediment from glacial Lake Columbia, upper coulee till, and a lower coulee lake that the fan itself impounded. Floods thus of debris-flow consistency carried outsize boulders previously thought transported by watery floods. Below Ephrata fan, a backflooded reach of Columbia valley received Grand Coulee outflow of small, late Missoula floods. These late floods can—by varve counts in post-S-ash deposits of Sanpoil valley—be clocked now as a decade or less apart. Still farther downstream, Columbia River gorge choked the largest Missoula floods, passing peak discharge only one-third to one-half that released by the breached Lake Missoula ice dam.

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Course of Columbia River in southern central Washington

Cited by 6 publications

References 0 publications

Geology and ground-water characteristics of the Hanford Reservation of the U.S. Atomic Energy Commission, Washington

Geology and ground-water characteristics of the Hanford Reservation of the U.S. Atomic Energy Commission, Washington

Flow directions in Columbia River Basalt flows and paleocurrents of interbedded sedimentary rocks, South-Central Washington

Upper Grand Coulee: New views of a channeled scabland megafloods enigma

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