Ancient Cataclysmic Floods in the Pacific Northwest: Ancestors to the Missoula Floods

Medley, E.

doi:10.15760/etd.581

Cited by 4 publications

(5 citation statements)

References 15 publications

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“…Megaflood evidence of the last ice age is most prevalent and studied. However, deposits of earlier large floods in the Columbia valley near Wenatchee, in Quincy basin, the Cheney-Palouse scabland tract, in Pasco basin, and possibly the Snake River Plain, show that megafloods have a long Quaternary history in the Columbia Basin, likely associated with earlier ice ages (Bretz et al 1956;Richmond et al, 1965;Baker, 1973;Patton and Baker, 1978b;Baker et al, 1991;Bjornstad et al, 2001;Lamb et al, 2008Lamb et al, , 2014Medley, 2012).…”

Section: Older Flood Episodes??mentioning

confidence: 99%

The Missoula and Bonneville floods—A review of ice-age megafloods in the Columbia River basin

O’Connor

Baker

Waitt

et al. 2020

Earth-Science Reviews

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The Channeled Scabland of eastern Washington State, USA, brought megafloods to the scientific forefront. A 30,000-km2 landscape of coulees and cataracts carved into the region's loess-covered basalt attests to overwhelming volumes of energetic water. The scarred landscape, garnished by huge boulder bars and far-travelled ice-rafted erratics, spurred J Harlen Bretz's vigorously disputed flood hypothesis in the 1920s. First known as the Spokane flood, it was rebranded the Missoula flood once understood that the water came from glacial Lake Missoula, formed when the Purcell Trench lobe of the last-glacial Cordilleran ice sheet dammed the Clark Fork valley in northwestern Idaho with ice a kilometer thick. Bretz's flood evidence in the once-remote Channeled Scabland, widely seen and elaborated by the 1950s, eventually swayed consensus for cataclysmic flooding. Missoula flood questions then turned to some that continue today: how many? when? how big? what routes? what processes?The Missoula floods passed through eastern Washington by a multitude of valleys, coulees and scabland tracts, some contemporaneously, some sequentially. Routings and their timing depended on the positions of various lobes of the multi-pronged Cordilleran ice sheet and the erosional development of the channels themselves. The first floods mostly followed the big bend of Columbia valley looping through north-central Washington. But the south-advancing Okanogan ice lobe soon blocked that path, forming long-lasting glacial Lake Columbia in the impounded Columbia valley. Missoula floods into this lake were diverted south out of the Columbia valley and into eastern Washington coulees and scabland tracts. At least four floods entered Moses Coulee, but then as the Okanogan lobe advanced over and blocked the head of that coulee, more eastern paths took the water, including Grand Coulee and the Telford-Crab-Creek and Cheney-Palouse scabland tracts. Flood routing also depended on the erosion of the coulees. At some point, headward erosion of upper Grand Coulee lowered the divide saddle between the west-running Columbia valley and the deep and wide Grand Coulee heading southwest. Still uncertain is when this happened and the consequences with respect to the stage and extent of glacial Lake Columbia and to flood access to the other, higher, flood routes. Downstream, all flood routes converged into Pasco Basin, flowed through Wallula Gap and the Columbia River Gorge into the Pacific Ocean, following submarine canyons and depositing sediment layers on abyssal plains.Please note that this is an author-produced PDF of an article accepted for publication following peer review. The definitive publisher-authenticated version is available on the publisher Web site.and perhaps older ones affected the Snake River Plain, some likely sourced in lakes dammed by alpine glaciers in central Idaho.

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Section: Older Flood Episodes??mentioning

confidence: 99%

The Missoula and Bonneville floods—A review of ice-age megafloods in the Columbia River basin

O’Connor

Baker

Waitt

et al. 2020

Earth-Science Reviews

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“…Pre-Wisconsinan floods may have also occurred in this area based on a few exposed deposits in the form of paleosols containing calcium carbonate or caliches that formed Bk and K soil horizons in the Pasco Basin having reversed magnetic polarity and being older than 700,000 years (Bjornstad and Fecht, 1989;Medley, 2012). Although these are suspected to have contributed to the physical expression of the Gorge, little evidence of them remain in the Gorge.…”

Section: Structurementioning

confidence: 99%

Characterization of the Red Bluff Landslide, Greater Cascade Landslide Complex, Columbia River Gorge, Washington

Randall¹

2000

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Located in the Columbia River Gorge, The Red Bluff Landslide (18.8 km 2) is one of four large landslides that make up the Cascade Landslide Complex. In its current form, the Red Bluff Landslide is a post-Missoula Flood feature made up of two components: an active upper lobe (8.6 km 2) that is translational, creeping to the south at 25 cm/yr and spreading laterally to the east at 6 cm/yr over a semi-fixed portion (10.2 km 2) of the Red Bluff Landslide area that has been "smoothed" by Missoula Floods. The upper active lobe is the landslide debris accumulated since Missoula Flood time (~15,000 yr. BP). Five separate collapse events have been identified and rock failures along the main scarp headwalls continue. Two rock avalanches on the Red Bluff Landslide were mapped. The Old Greenleaf Basin Rock Avalanche is estimated to have occurred 100 to 150 years ago, represents the fifth collapse event on the Red Bluff Landslide, and covers an area of 200,000 m 2. It has a volume of 4.2 million m 3 ; its length is 748 m and has a width of 215 m. On January 3, 2008, the Greenleaf Basin Rock Avalanche occurred, flowing over the Old Greenleaf Basin Rock Avalanche, covering an area of 100,000 m 2 and deposited a volume of about 375,000 m 3. Its length is 730 m with an average depth of 1.22 m. It contributed approximately 0.058% of the total volume and 0.01% of the surface area to the active upper lobe portion of the Red Bluff Landslide. The Greenleaf Basin Rock Avalanche was determined to be insignificant in the movement of the active part of the Red Bluff Landslide during the winter of 2007-2008. The original Cascade Landslide Complex map (Wise, 1961) included the Mosley Lakes Landslide which has now been removed because it lacked the characteristics of a landslide like a scarp. The original ii complex (35.5 km) has been renamed the "Greater Cascade Landslide Complex" (43.0 km 2), with the addition of the adjacent Stevenson Slide and the elimination of the Mosley Lakes Landslide. iii Acknowledgments First and foremost, I want to thank Scott Burns for his patience, his constructive criticism, advice, and most of all, the encouragement provided in my thesis work. This gave me a boost for finishing this work and has meant a lot to me. A special thanks has to be given to Russ Evarts (USGS, Menlo Park, California) whom I accompanied on a couple of field excursions. The hike from Wanna Point down to Eagle Creek was quite the challenge. Russ was worth a couple of classes in Columbia River Basalts. Jim O'Connor of USGS Portland provided me with a few pointers regarding interpretation of LiDAR imagery-thank you Jim. Tom Pierson of the Cascade Volcano Observatory in Vancouver, Washington was accommodating in letting me accompany him in setting up pins for GPS monitoring on the Red Bluff Landslide-thank you Tom. I also want to thank Andrew Fountain, committee member, who was especially helpful with final revision suggestions on my thesis. Thanks to David Scofield of the USACE who let me rifle through the volumes of material the USACE had ...

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“…It is reasonable to note that the differences between such megafloods from glacial lake outburst floods are rather artificial (Bennett & Glasser, 2009). Now, up to 90 floods linked with the Missoula lake are reported from the time interval of 18-15 ka, although there is evidence that similar floods occurred through the entire Pleistocene (O'CONNOR & BAKER, 1992;BENITO & O'CONNOR, 2003;CLAGUE et al, 2003PLUHAR et al, 2006ANDERSON & ANDERSON, 2010;MEDLEY & BURNS, 2010). MEDLEY & BURNS (2010) traced the history of these floods back to 780 ka at least.…”

Section: Megafloods: Scaling By Spatial Extentmentioning

confidence: 99%

“…Now, up to 90 floods linked with the Missoula lake are reported from the time interval of 18-15 ka, although there is evidence that similar floods occurred through the entire Pleistocene (O'CONNOR & BAKER, 1992;BENITO & O'CONNOR, 2003;CLAGUE et al, 2003PLUHAR et al, 2006ANDERSON & ANDERSON, 2010;MEDLEY & BURNS, 2010). MEDLEY & BURNS (2010) traced the history of these floods back to 780 ka at least. Lake Missoula was up to 200 m deep, and its volume was about 2700 km 3 , which allowed peak discharges of 13000000 m 3 /s and the duration of one flood during about a week (ANDERSON & ANDERSON, 2010).…”

Section: Megafloods: Scaling By Spatial Extentmentioning

confidence: 99%

Catastrophes versus events in the geologic past: how does the scale matter?

Gutak

Ruban

2013

Cad Lab Xeol Laxe

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Catastrophes were common in the geologic past, but their distinction from other events is necessary. Besides magnitude (strength), scales of events are important in a solution of this task. Several examples, which involve Late Paleozoic and Quaternary megafloods, Hadean and Phanerozoic extraterrestrial impacts, and Phanerozoic mass extinctions, ensure that scaling by spatial extent and diversity of consequences facilitates tracing the boundary between catastrophes and “ordinary” events. This boundary, however, is dynamic and its position depends on our subjective needs. Considerations of the geologic past should not mix catastrophes of different scales. The event analysis helps to avoid such a pitfall, and, therefore, it should be preferred to neocatastrophism in modern geoscience.

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Ancient Cataclysmic Floods in the Pacific Northwest: Ancestors to the Missoula Floods

Cited by 4 publications

References 15 publications

The Missoula and Bonneville floods—A review of ice-age megafloods in the Columbia River basin

The Missoula and Bonneville floods—A review of ice-age megafloods in the Columbia River basin

Characterization of the Red Bluff Landslide, Greater Cascade Landslide Complex, Columbia River Gorge, Washington

Catastrophes versus events in the geologic past: how does the scale matter?

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