Glacial Lake Missoula

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Glacial Lake Missoula

• Logan King
• 4-29-2009

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• Most spectacular phenomenon of the quaternary
  (Baker Bunker 1985)
• Resulted in the most intense floods known from
  the geological record (Clarke et al. 1984)

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Formation

• When
• Late Pleistocene (Wisconsinen)
• 16-12,000 ybp
• Where
• 2 Branches
• Purcell Trench Max

http//www.nps.gov/iceagefloods/J-ext1.JPG
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Thoeries

• Forty-Floods
• Single Flood
• Dozens-of-Floods
• 40 Floods?

http//formontana.net/shores.jpg
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Discharge

• Ocean sediment
• Largest event 700km3
• Total1450km3
• Order of magnitude calc.
• (Normark Ried 2003)

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Velocities

• Land based calc. from sediment movement
• _at_ source 17 x106 m3 s-1
• _at_ Channeled Scablands 10 x106 m3 s-1
• Max. Volume 1000k m3

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Flood Constraints

• Purcell Trench Lobe
• 750 m water height
• 12-40 Floods

• Okanogan Lobe
• Relatively normal outflow
• 500 m water height
• 465 m dam height
• Persisted longer 3000 yrs
• 89 floods

• Missoula

• Columbia

Atwater 1987
http//www.nwcreation.net/images/geology/scablands
/lakemissoula.jpg
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Jökulhlaups

• Drainage
• Full or Partial?
• Failure
• Floating
• Carving (ducts)
• Down cutting
• Waves

http//www3.hi.is/oi/Iceland20excursion/Kotlubja
rg.jpg
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Case study 1

• Climatic records
• 16-12,000 ybp
• Regular recurrence
• Forty floods hypo. 35 failures
• Floating?
• Max water elev. 1265 1079m
• Max depth of 635 449
• (Baker Bunker 1985)

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Case study 2

• Computer simulation
• 4 tests-gt 2 partial drains
• Carving-duct style failure
• 2 different duct shapes
• Creep closure
• (Clarke et al. 1984)

• Closure lt100 hrs.
• Velocity 13.6-26.1 m/s
• Area 2.01-5.26 x 105 m2
• Fracture?

• Model

• Results

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A Little Perspective

• Total global river discharge 1.2 x x106 m3 s-1
• Volume of outburst floods 3 orders of mag.
  greater then any observed

http//www.nationsonline.org/gallery/Earth/earth-m
ap.jpg
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Conclusion

• Largest flood events known
• No modern day analogues
• Massive force in landscape development and
  sediment transport
• Purcell Lobe formation
• Columbia lake control
• Groundbreaking concept

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References

• Evans, D, Benn, D (1998). Glaciers and
  Glaciation.London Hodder.
• Normark W.R. , Ried J.A. 2003. Extensive deposits
  on the Pacific plate from Late Pleistocene North
  American glacial lake outbursts. Journal of
  Geology. 111 (6)617-637.
• Steele W.K. 1991. Paleomagnetic evidence for
  repeated glacial Lake Missoula floods from
  sediments of the Sanpoil River valley,
  northeastern Washington. Quaternary Research. 35
  (2)197-207.
• Atwater B.F. 1987. Status of glacial Lake
  Columbia during the last floods from glacial Lake
  Missoula. Quaternary Research. 27 (2)182-201.
• Clarke G.K.C., Mathews W.H., Pack R.T. 1984.
  Outburst floods from glacial Lake Missoula.
  Quaternary Research. 22 (3)289-299.
• Baker V.R., Bunker R.C. 1985. Cataclysmic Late
  Pleistocene flooding from glacial Lake Missoula
  a review. Quaternary Science Reviews. 4 (1)1-41.
• Waitt Jr R.B. 1984. Periodic jokulhlaups from
  Pleistocene glacial Lake Missoula - new evidence
  from varved sediment in northern Idaho and
  Washington. Quaternary Research. 22 (1)46-58.
• Lopes, C., Mix, A.C., 2009. Pleistocene
  megafloods in the Northeast Pacific. Geological
  Society of America (GSA), Boulder, CO, United
  States (USA). vol. 37, no. 1, pp.79-82.
• Gaylord D.R., Pope M.C., Cabbage P.R., Glover
  J.F.III, Anfinson O.A., Baar E.E., Vervoort J.D.,
  2007. Provenance of glacial outburst flood
  deposits in the Channeled Scabland, WA influence
  of glacial Lake Missoula, melt water, Snake
  River, and Bonneville flood sources. Geological
  Society of America (GSA), Boulder, CO, United
  States (USA). vol. 39, no. 6, pp.82.
• Costa J.E., Schuster R.L., 1988. The Formation
  and Failure of Natural Dams. . Geological Society
  of America (GSA), Boulder, CO, United States
  (USA). vol. 100, no. 7, pp. 1054-1068.