cataclysms on the columbia: the great missoula floods
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Geology lecture about the Missoula Floods and how they shaped the Columbia GorgeTRANSCRIPT
Cataclysms on the
Columbia
The Great Missoula Floods
Dr. John Eliot AllenDr. Marjorie BurnsDr. Scott BurnsPortland State University
Ooligan Press, PSU
1) Name for the Floods is Missoula Floods not Bretz Floods
2) Dates are in Calendar Years not C-14 Years
3) Color Photos4) Maps are shaded relief
maps for easier reading5) Rest of the Story added
for history of the Floods6) Totally updated science
of the floods
New Things in the Second Edition of the Book:
Darryl Lloyd photo
In front of Mt. Rushmore
“Five great men in one picture – four of them don’t show”
J Harlen Bretz
Bretz et al in the Grand Coulee, ca 1928
Bretz, circa 1910
Photo: Darryl Lloyd
A “Palouse Island” along I-90, about 5 miles north of Sprague, Washington
Big whorls have little whorls,
Which feed on their velocity:
Little whorls have smaller whorls
And so unto viscosity. JEA p31
Strand lines on the Washington side of the Columbia River Gorge
Bretz, 1933
USGS Controversy
James Gilluly G.R. MansfieldO.E. Meinzer
Revisionists
Ira Allison Richard Foster Flint
J.T. Pardee Breaks the Silence
Vindication
Before Bretz dies in 1981 at 98 years of age
The Rest of the Story1979 photo
Richard Waitt
Burlingame Gulch near Touchet, WashingtonExposing 40 rhythmite beds
Burlingame Gulch near Touchet, WashingtonExposing 40 rhythmite beds
Set S Mt. St. Helens Ash near Mabton in the Yakima Valley
Brian Atwater
Close-up of 2 rhytmites showing varved annual layers of silt and clay
Dating the Missoula FloodsDating the Missoula Floods
• Radiocarbon Dating: 15,300 – 12,700 BP
• Calendar Years (Calibrated Dates: 15,000 – 18,000 years ago)
• 40 events came to Portland area
• 90 events came to Spokane
Altai Mountains
Glacial Lake Missoula:1) 530 mi3 water2) 50 mi3 ice3) 2100 feet deep4) Elevation: 4250 ft.
Ancient beach strand lines can
still be seen
Lake Missoula was ~ ½ the size of Lake
Michigan
Nine Mile Section:1) Pale: river deposits (36)2) Dark: varves (1000)3) oldest: 58 varves
1) 2400 ft. Elevation
2) Up to 500 ft deep
Grand Coulee
Dam
Spokane
Odessa
Potholes in Quincy Basin
Palouse Falls
Wallula Gap
Mt. St. Helens double ash layers, age 13,000 between 29th and 30th layer
Columbia River, west of Philippi Canyon
Gravel bar formed at entrance to Philippi Canyon
Bonneville
Beacon Rock – Columbia Gorge
Rooster Rock (has had different names in the past)
Swan Island
If the Missoula Floods were to occur today
Willamette Meteorite (1902 photo)
1905 exposition
Foreset beds in Durham Pits – now under Bridgeport
15,000 year old soil overlies on older paleosol in the loess
1935 Ira Allison map
Bellevue Erratic – argillite – 1950 measured approx. 160 tons, now approx. 40 tons
Irish Bend south of Corvallis
Floodwaters, entrained sediments and turbid currents that swept across
the Pacific Ocean floor for 700 miles (1100 km).
Normark et al. (2000)
Ancient Cataclysmic Floods5 Ancient Cataclysmic Floods exposed in paleosols near The Dalles
Volcanic Soils on the hills of Dundee, OregonVolcanic soils on the hills of Dundee, Oregon
Terroir Differences in PNWTerroir Differences in PNW
• Washington: 95% of the vineyards are on Missoula Flood sediments; Vigor controlled by irrigation.
• Oregon: 90% of vineyards are on upland vineyards and 10% are on Missoula Flood sediments; Vigor controlled by low nutrient, old soils.
Conclusions - But Not The End of the Story
• 89+ floods, with 40 getting to Portland
• Velocities up to 60 mph
• Flows = 10 x the total flow of all of the world’s rivers
• Effects of the Floods: 16,000 square miles
• Maximum Floods were the first ones: 530 mi3 of water and 50 mi3 of ice; biggest were first floods
Future
• More information from Ancient Cataclysmic Floods
• More information of time of the Floods passing the “Lakes”
• More information from the deep sea record
• New National Park will bring visitors to the region and new research will unlock further secrets