Lewis and Clark's Columbia River
Home Regions Campsites Penny Postcards My Corps of Discovery Image Index Links About This Site Main Menu
Lewis & Clark's Columbia River - "200 Years Later"
"Missoula Floods"
Includes ... Missoula Floods ... Lake Missoula ... Lake Lewis ... Lake Condon ... Lake Allison ... Columbia River Basalt Group (CRBG) ... Wallula Gap ... Hat Rock ... Alkali Canyon, Jones Canyon, Blalock Canyon, and Philippi Canyon ... Stonehenge and Maryhill Museum ... Fairbanks Gap ... Horsethief Butte ... Tom McCall Nature Preserve ... Hood River ... Beacon Rock ... Multnomah Falls and Crown Point ... Rocky Butte ... Kalama Gap ... Nicolai Ridge and Clatsop Crest ...
Image, 2005, Wallula Gap from Juniper Canyon, Oregon, click to enlarge
Click image to enlarge
Wallula Gap, as seen from Juniper Canyon, Oregon. The waters of the Missoula Floods poured through the Wallula Gap thousands of years ago. Image taken September 25, 2005.


Glacial Lake Missoula and the Missoula Floods ...
Between 80,000 years ago and 10,000 years ago ice sheets called the "Wisconsin Glaciation" covered much of North America, including Northern Washington, Idaho, and Montana. Towards the end of this glaciation a large ice dam blocked the Clark Fork River in the Idaho Panhandle, creating "Glacial Lake Missoula". This lake was a massive lake 2,000 feet deep filling the valleys of western Montana. It stretched eastward more than 200 miles and, at its maximum height and extent, contained more than 500 cubic miles of water - more water than Lake Erie and Lake Ontario combined. Periodically, the ice dam would fail, resulting in a large catastrophic flood of ice- and dirt-filled water which rushed across northern Idaho and eastern and central Washington, down the Columbia River, through the Columbia River Gorge, and finally poured into the Pacific Ocean at the mouth of the Columbia River. Flood waters filled the Willamette River Valley, reaching Eugene, Oregon, more than 100 miles away. When Lake Missoula burst through the ice dam and exploded downstream, it did so at a rate 10 times the combined flow of all the rivers of the world.

"... This towering mass of water and ice literally shook the ground as it thundered towards the Pacific Ocean, stripping away thick soils and cutting deep canyons in the underlying bedrock. With flood waters roaring across the landscape at speeds approaching 65 miles per hour, the lake would have drained in as little as 48 hours. But the Cordilleran ice sheet continued moving south and blocking the Clark Fork River again and again, creating other Glacial Lake Missoulas. Over thousands of years, the lake filling, dam failure, and flooding were repeated dozens of times, leaving a lasting mark on the landscape of the Northwest. Many of the distinguishing features of the Ice Age Floods remain throughout the region today. ..." [U.S. National Park Service, Ice Age Institute website, 2005]

Along the floodwaters’ path, more than 50 cubic miles of earth and rock were removed, transported, and much was deposited as new landforms. The floods built gravel bars as tall as 400 feet and moved boulders weighing many tons and deposited them high on the valley walls. Most of the eroded material was carried out onto the floor of the Pacific Ocean, where extensive deposits of flood sediment have been identified hundreds of miles from the current mouth of the Columbia River. According to Geologist Richard Waitt of the U.S. Geological Survey (1985), the various limits on the ice sheet and the floods suggests that Glacial Lake Missoula existed for 2,000 to 2,500 years between 15,300 and 12,700 years ago, creating more than 40 and maybe up towards 60 separate flood events.


The Floods ...
The Missoula Flood waters passing Wallula Gap reached an elevation of about 1,200 feet, as evidenced by glacial erratics that were left stranded on the slopes of the Horse Heaven Hills and other nearby ridges. At The Dalles the waters reached 1,000 feet and by the time the flood waters reached Crown Point the surface had dropped to 600 to 700 feet. The area between Portland and the restriction at Kalama was under 400 feet of water. Clatskanie, Oregon, was buried under 275 feet of water. By the time the flood waters reached Astoria they were near sea level.

Missoula Flood heights (measured and estimated) as listed in Allen and Burns (1986) were


Lake Lewis, Lake Condon, and Lake Allison ...
The restriction of Missoula Flood waters at the Wallula Gap created a backwater lake called "Lake Lewis". Lake Lewis covered more than 2,000 square miles of the Pasco and Quincy Basins, the Walla Walla River Basin, and the Lower Snake River.

The restriction at The Dalles created "Lake Condon", which covered approximately 1,500 square miles from The Dalles to Umatilla.

The restriction at Kalama created a backwater lake, known as "Lake Allison". This lake filled the Willamette River Valley as far as Eugene, Oregon, over 100 miles away, with a measured height of 400 feet at Oregon City and an estimated height of 380 feet at Eugene. The area covered was approximately 3,000 square miles. The flood waters dumped thick layers of Palouse Silt, making the Willamette Valley one of the most fertile agricultural lands in the country.



Along the Flood Path

  • Columbia River Mile (RM) 308 ... Wallula Gap ...
  • RM 298 ... Hat Rock ...
  • RM 243 to RM 227 ... Alkali Canyon, Jones Canyon, Blalock Canyon, and Philippi Canyon ...
  • RM 210 ... Stonehenge ...
  • RM 205 ... Maryhill Museum ...
  • RM 200 ... Fairbanks Gap ...
  • RM 194 ... Horsethief Butte ...
  • RM 180 ... Rowena Gap ...
  • RM 180 ... Klickitat River and Lyle ...
  • RM 180 ... Rowena Crest ...
  • RM 180 ... Tom McCall Nature Preserve ...
  • RM 175 ... Mosier ...
  • RM 171 ... Bingen Gap ...
  • RM 169 ... Hood River ...
  • RM 142 ... Beacon Rock ...
  • RM 136 ... Multnomah Falls ...
  • RM 129 ... Crown Point ...
  • RM 113 ... Rocky Butte ...
  • Granitic Erratic, Multnomah County, Oregon ...
  • Glacial Erratic, Yamhill County, Oregon ...
  • RM 71 ... Kalama Gap ...
  • RM 40 ... Nicolai Ridge and Clatsop Crest ...


Columbia River Mile (RM) 308 ... Wallula Gap ...
Many features along the Columbia River were impacted or created by the Missoula Floods. The Wallula Gap near the eastern end of the Columbia River restricted flood waters creating a temporary "Lake Lewis". Lake Lewis stretched back into the Yakima River Valley and covered the today's cities of Richland, Pasco, and Kennewick.

Image, 2003, Wallula Gap from downstream, click to enlarge
Click image to enlarge
Wallula Gap, Washington The flood crest at the Wallula Gap was about 1,200 feet as evidenced by glacial erratics left stranded on the hillsides. View from downstream from a pullover on Highway 730, just east of Sand Station Recreation Area, Oregon. Image taken September 29, 2003.


RM 298 ... Hat Rock, Oregon ...
Downstream from the Wallula Gap is Hat Rock, a basalt remnant created by the eroding waters of the Missoula Floods. Lewis and Clark passed Hat Rock on October 19, 1805.

Image, 2004, Hat Rock, Oregon, click to enlarge
Click image to enlarge
Hat Rock, Oregon. Hat Rock is a remnant of a Columbia River Basalt flow, eroded during the Missoula Floods. Image taken September 24, 2004.

"... a rock in a Lard. resembling a hat just below a rapid at the lower Point of an Island in the Midl: of the river ..." [Clark, October 19, 1805, first draft]


RM 243, RM 239.5, RM 234, and RM 227.5 ... Alkali Canyon, Jones Canyon, Blalock Canyon, and Philippi Canyon ...
Flood waters of Lake Condon of the Missoula Floods spilled over the southern bank of the Columbia River and headed south through Alkali Canyon (RM 243), Jones Canyon (RM 239.5), Blalock Canyon (RM 234), and Philippi Canyon (RM 227.5). The waters rushing through Alkali Canyon flowed to Rock Creek to the John Day River and then northwest along the John Day River drainage back to the Columbia River (RM 217). The waters flowing up Jones, Blalock, and Philippi Canyons created a scabland before entering the John Day River drainage.

SPILLWAYS INTO THE JOHN DAY CANYON

"Hodge (1931) recognized more than 50 years ago that floodwaters had overtopped the low divides between the Columbia River and the headwaters of Rock Creek, as well as the divide directly into the John Day Canyon. The floodwater poured up Alkali Canyon, south of Arlington (Oregon 19), and scoured a channel westward (now occupied by the Union Pacific RR branch line) into Rock Creek 6 miles above its junction with the John Day River. Farther west, the Floods poured up Jones Canyon, Blalock Canyon, and Phillip Canyon just east of Quinton, where it formed several square miles of scabland and left a high-perched expansion bar on the east wall of the John Day Canyon 10 miles from its mouth. A sixth small spillway lies at 1020 feet elevation, 2 miles northwest of Phillipi Canyon."

Source:    John Eliot Allen and Marjorie Burns, with Sam C. Sargent, 1986, Cataclysms on the Columbia: Timber Press, Portland, Oregon



RM 210 and RM 205 ... Stonehenge and Maryhill Museum, Washington ...
Washington State's Maryhill Museum and Stonehenge Memorial sit on a bench cut into the north wall of the Columbia Hills by the Missoula Floods. In places this bench is nearly one mile wide.

Image, 2004, Stonehenge Memorial sitting on the banks of the Columbia River, click to enlarge
Click image to enlarge
Stonehenge Memorial, Maryhill, Washington, perched on the banks of the Columbia River. Image taken April 24, 2004.
Image, 2005, Maryhill Museum, Washington, as seen from Interstate 84, Oregon, click to enlarge
Click image to enlarge
Maryhill Museum and the Columbia Hills, Washington, as seen from Interstate 84, Oregon. Maryhill Museum sits on a large bench carved by the Missoula Floods. Image taken September 24, 2005.


RM 200 ... Fairbanks Water Gap, Oregon ...
The Fairbanks Water Gap was created when flood waters from the Missoula Floods "jumped banks" and flowed through the gap into Fifteenmile Creek, eight miles east of The Dalles, Oregon.

Image, 2011, Avery Park, Washington, and Fairbanks Water Gap, Oregon, click to enlarge
Click image to enlarge
Avery Park, Washington, with Fairbanks Water Gap, Oregon. Waters from the Missoula Floods flowed through the Fairbanks Water Gap into Fifteenmile Creek, east of The Dalles, Oregon. Image taken September 28, 2011.


RM 194 ... Horsethief Butte, Washington ...
The great floods of the last ice age carved the basalts of Horsethief Butte and the surrounding Columbia River channel, creating the features we see today. The basalts themselves were created thousands of years earlier when a series of lava flows emerged from cracks in the earth's crust and blanketed the entire eastern Washington and northern Oregon region. Horsethief Butte is made up of a series of lava flows, visible in the cliffs.

Image, 2011, Horsethief Butte and Horsethief Lake, click to enlarge
Click image to enlarge
Horsethief Butte and Horsethief Lake. View from Columbia Hills State Park (Horsethief Lake State Park). Image taken September 28, 2011.


RM 180 ... Rowena Gap ...
The Columbia River passes through the Ortley Anticline at Rowena Gap, a major constriction in the path of the Missoula Floods. Flood waters backed up for miles upstream and an eddy bar developed downstream.

RM 180 ... Klickitat River and Lyle, Washington ...
Stratigraphy in exposures of eddy deposits northwest and across the Klickitat River from Lyle show that MANY of the several floods passing by achieved stages of 600 feet. The community of Lyle is built on a huge Missoula Floods gravel bar.

RM 180 ... Rowena Crest ...
Rowena Crest sits at an elevation of 720 feet and was stripped of its pre-Missoula-flood surface. Estimates give a 960 +/- 40 feet water elevation.

"Between The Dalles and Hood River, soil and talus were swept from the valley walls, leaving the series of clean steps we now see on the barren lava flows of Columbia River Basalt. At many places the accumulations of talus, which one would expect to see after 15,000 years at the base of the cliffs, have yet to form substantial slopes. Just west of Mayer State Park (US 30), the river makes an abrupt turn to the north. This change in the course of the floods caused the cliffs to be undermined so extensively that a great landslide developed, down which the Scenic Highway swings in a series of turns (Rowena Loops).

The almost vertical 600-foot-high cliffs here were overtopped by at least 200 feet of water, which cleaned off much of the overlying The Dalles Formation and left several scabland channels, one of them by the highway containing a small kolk lake."


Source:    Allen, J.E., and Burns, M., 1986, Cataclysms on the Columbia, Timber Press, Portland.


RM 180 ... Tom McCall Nature Preserve, Oregon ...
The Tom McCall Nature Preserve and nearby Rowena Crest are located on a high basalt mesa known as the "Rowena Plateau". During the end of the last ice age over 200 feet of raging flood waters (today known as the Missoula Floods) ripped across this plateau stripping it clean. Over the next ten thousand years this surface was covered by 3 to 4 feet of loess (wind blown ash, most likely from nearby Mount St. Helens volcano) which eventually eroded into the mounds. These mounds, wildflower-covered in the spring, dot the surface of the basalt flow. They are commonly referred to as "biscuit mounds" or "biscuit scabland".

The Missoula Floods also left behind small rounded depressions in the basalts which eventually filled with water and are now called "kolk lakes". The trails at Tom McCall pass by two such lakes.


Image, 2009, Tom McCall Nature Preserve, Oregon, click to enlarge
Click image to enlarge
Rowena Plateau, Tom McCall Nature Preserve, Oregon, with the Columbia River. Gold Stars dot the hillside. Image taken April 4, 2009.
Image, 2007, Tom McCall Nature Preserve, Oregon, click to enlarge
Click image to enlarge
Loess mounds, Rowena Plateau, Tom McCall Nature Preserve, Oregon. Image taken May 13, 2007.
Image, 2007, Tom McCall Nature Preserve, Oregon, click to enlarge
Click image to enlarge
Kolk Lake, Rowena Plateau, Tom McCall Nature Preserve, Oregon. Image taken May 13, 2007.


RM 175 ... Mosier, Oregon ...
At Mosier, Oregon, Missoula flood waters spilled over the divide from the Columbia River to Mosier Creek.

RM 171 ... Bingen Gap ...
The Bingen Gap is a constriction in the Columbia River where the Columbia crosses the Bingen Anticline.

RM 169 ... Hood River, Oregon ...
The Hood River Valley was inundated by backwater from the Missoula Floods, with flood deposits reaching above 800 feet, with some ice-rafted erratics thought to be Missoula Flood erratics being between 840 and 880 feet. Peak high is estimated at approximately 925 feet.

RM 142 ... Beacon Rock, Washington ...
Beacon Rock is a large 840-foot-high basalt plug. The Missoula Floods eroded away the softer outer material.

Image, 2010, Beacon Rock, Washington, click to enlarge
Click image to enlarge
Beacon Rock and Hamilton Mountain, Washington. Beacon Rock is a large 840-foot-high basalt plug. The Missoula Floods eroded away the softer outer material View from Beacon Rock boat dock. Image taken November 2, 2010.


RM 136 and RM 129 ... Multnomah Falls and Crown Point, Oregon ...
The 700-foot-high Crown Point was inundated during peak floods, and the nearby 620-foot-high cliff at Multnomah Falls was enhanced when flood waters of the Missoula Floods eroded away softer material, highlighting the spectacular cliff face.

Imag5, 2005, Multnomah Falls, Oregon, Benson Bridge, click to enlarge
Click image to enlarge
Multnomah Falls, Oregon, with Benson Bridge. Multnomah Falls, located near Portland, Oregon, drops 620 feet over Grande Ronde Basalt of the Columbia River Basalt Group. The Missoula Floods enhanced the cliff face, eroding away loose and softer materials. At Multnomah Falls the visitor can view six flows in the cliff face, with pillow flows being visible in the upper sequence near the lip of the Upper Falls. Image taken March 6, 2005.
Image, 2006, Crown Point from Chanticleer Point, Oregon, click to enlarge
Click image to enlarge
Crown Point, Oregon, as seen from Chanticleer Point, Oregon. Crown Point is a remnant of a massive Priest Rapids intracanyon lava flow. The Priest Rapids is a member of the Wanapum Basalt of the Columbia River Basalt Group (CRBG), and erupted in the middle Miocene. The 700-foot-high feature was covered by waters of the Missoula Floods. Image taken September 23, 2006.


RM 113 ... Rocky Butte, Oregon ...
Rocky Butte stood in the path of the Missoula Floods. The rushing flood waters heading down the Willamette Valley eroded the land on the upstream side of the Butte, similar to how a stream erodes the sediment on the upstream side of a rock in its path. Today on the east side of Rocky Butte, Interstate 205 and Interstate 84 follow the broad channels carved by the floods.

"... Rocky Butte, an early Pleistocene basaltic andesite volcano of the Boring Lava. ... During peak flows of the latest Pleistocene Missoula floods, high velocities and turbulence induced by the submerged butte eroded huge scour pits on its upstream side; downstream, gravel bars many kilometers long were deposited. I-84 curves around the south and east sides of the butte in scour pits." [Scott, 1997, Geologic History of Mount Hood Volcano, Oregon, USGS Open-file Report 97-263]

Image, 2006, Rocky Butte, Oregon, and Interstate 205, from the south, click to enlarge
Click image to enlarge
Rocky Butte, Oregon, and Interstate 205. View from the south. Image taken February 19, 2006.


Granitic Erratic, Multnomah County, Oregon ...
(to come)

Image, 2014, Granitic Erratic, Lewis and Clark College, Portland, Oregon, click to enlarge
Click image to enlarge
Granitic Erratic, Lewis & Clark College, Multnomah County, Portland, Oregon. Image taken August 24, 2014.
Image, 2014, Granitic Erratic, Lewis and Clark College, Portland, Oregon, click to enlarge
Click image to enlarge
Granitic Erratic, Lewis & Clark College, Multnomah County, Portland, Oregon. Image taken August 24, 2014.
Image, 2014, Granitic Erratic, Lewis and Clark College, Portland, Oregon, click to enlarge
Click image to enlarge
Granitic Erratic, Lewis & Clark College, Multnomah County, Portland, Oregon. Image taken August 24, 2014.

A GRANITIC ERRATIC
CARRIED BY AN ICE-BERG
AT THE END OF THE LAST
ICE AGE FROM THE UPPER
COLUMBIA RIVER BASIN
TO NEAR THIS POINT.


Glacial Erratic, Yamhill County, Oregon ...
The "Sheridan Erratic", often called the "Bellevue Erratic", is located on the west side of the Willamette Valley, just off of Oregon Highway 18, and halfway between the Oregon communities of Sheridan and McMinnville. According to Dr. Jim O'Connor in an interview with the Yamhill Valley News-Register" (2005):   "the 90-ton rock, which sits atop a rise about a half mile from the site entrance, probably came in on an iceberg around 15,000 years ago, transported by one of the Missoula floods, the biggest known fresh water floods in history. The erratic rock is at an elevation of 300 feet and the floods probably topped that by 100 feet." The News-Register goes on to say:   "More than 400 ice-rafted rocks have been identified along the flood plain ... they are different in composition from the local bedrock, thus are called "erratic" and the one near Sheridan is the largest known glacial erratic in the Willamette Valley." Geologically the rock is an argillite boulder from Canada and is believed to be 600 million years old. It was originally part of the sea-floor. It once weighed 160 tons and measured nearly 21 x 18 x 5 feet. Today the boulder sits in many pieces with the largest being nearly 18 x 13 x 5 feet, and weighs in at 90 tons. Vandalism and souvenier hunters have taken the rest.

Image, 2013, Glacial Erratic, McMinnville, Oregon, click to enlarge
Click image to enlarge
Sign, Glacial Erratic, McMinnville, Oregon. Image taken January 11, 2013.
Image, 2013, Glacial Erratic, McMinnville, Oregon, click to enlarge
Click image to enlarge
Glacial Erratic, McMinnville, Oregon. Image taken January 11, 2013.
Image, 2013, Glacial Erratic, McMinnville, Oregon, click to enlarge
Click image to enlarge
Glacial Erratic, McMinnville, Oregon. Image taken January 11, 2013.
Image, 2013, Glacial Erratic, McMinnville, Oregon, click to enlarge
Click image to enlarge
Glacial Erratic, McMinnville, Oregon. Image taken January 11, 2013.
Image, 2013, Glacial Erratic, McMinnville, Oregon, click to enlarge
Click image to enlarge
Glacial Erratic, McMinnville, Oregon. Image taken January 11, 2013.


RM 71 ... Kalama Gap ...
The constriction between Carrolls Bluff on the Washington side of the Columbia and the bluff on the Oregon side just north of Prescott Beach backed up flood waters from the Missoula Floods into the Willamette Valley. This constriction is known as "Kalama Gap". Flood heights are estimated to have been around 400 feet.

Image, 2013, Kalama, Washington, click to enlarge
Click image to enlarge
Carroll's Bluff, Washington, as seen from Interstate 5. View looking north. Image taken February 2, 2013.
Image, 2016, Prescott Point, Oregon, click to enlarge
Click image to enlarge
Prescott Point (Prescott Bluff) as seen from Prescott Beach County Park, Oregon. Image taken September 9, 2016.


RM 40 ... Nicolai Ridge and Clatsop Crest, Oregon ...
Nicolai Ridge and Clatsop Crest is a long basalt ridge on the Oregon side of the Columbia River which was undercut by Missoula flood erosion, resulting in a steep north face towering over Westport and Wauna, Oregon, and Puget Island, Washington. Bradley State Wayside, downstream of Wauna, sits upon this ridge and provides great views. Bradley State Wayside is at Columbia River Mile (RM) 40.

Image, 2012, Brownsmead, Oregon, click to enlarge
Click image to enlarge
Nicolai Ridge near Wauna, Oregon. View from moving car. Image taken September 22, 2012.


From the Journals of Lewis and Clark ...

Clark, ...
 




Columbia RiverReturn to
Menu
 



SNAKE RIVER CONFLUENCE | COLUMBIA PLATEAU
COLUMBIA RIVER GORGE | VANCOUVER PLAINS | JOURNEY TO THE PACIFIC
CAMPSITES


HOME | REGIONS | PENNY POSTCARDS | MY CORPS OF DISCOVERY
IMAGE INDEX | LINKS | ABOUT THIS SITE


COLUMBIA RIVER IMAGES - HOME
NORTHWEST JOURNEY - HOME
NORTHWEST BIRDING
RIDGEFIELD NWR - BIRDS
COMPLETE BIRD LIST - PHOTOS
THE BARLOW ROAD
THE COLUMBIA RIVER HIGHWAY
WILDFLOWERS and WEED BLOSSOMS



*River Miles [RM] are approximate, in statute miles, and were determined from USGS topo maps, obtained from NOAA nautical charts, or obtained from the U.S. Army Corps of Engineers website, 2003

Sources:    Allen, J.E., and Burns, M., 1986, Cataclysms on the Columbia, Timber Press, Portland;    Bishop, E.M., 2004, Hiking Oregon's Geology, The Mountaineers Press;    DeKay, L., and Hurd, T., 2011, Columbia River Gorge Chapter Ice Age Floods Institute, 2011 Field Trip;    Minervini, J.M., O'Connor, J.E., and Wells, R.E., 2003, "Maps showing inundations depths, ice-rafted erratics, and sedimentary facies of late Pleistocene Missoula Floods in the Willamette Valley, Oregon", U.S. Geological Survey;    Norman, D.K, Busacca, A.J., and Teissere, R., 2004, Geology of the Yakima Valley Wine Country -- A Geologic Field Trip Guide from Stevenson to Zillah, Washington, Washington Division of Geology and Earth Resources Field Trip Guide 1, June 2004;    Norman, D.K., and Roloff, J.M., 2004, A Self-Guided Tour of the Geology of the Columbia River Gorge -- Portland Airport to Skamania Lodge, Stevenson, Washington: Washington Division of Geology and Earth Resources, Open-File Report 2004-7, March 2004;    O'Connor, J.E., Dorsey, R.J., and Madin, I.P., 2009, "Volcanoes to Vineyards: Geologic Field Trips Through the Dynamic Landscape, Geological Society of America;    Scott, W.E., Gardner, C.A., Sherrod, D.R., Tilling, R.I., Lanphere, M.A., and Conry, R.M., 1997, Geologic History of Mount Hood Volcano, Oregon - A Field-Trip Guidebook, USGS Open-File Report 97-263;    U.S. National Park Service website, 2005, "Ice Age Floods Institute";    Waitt, R.B., 1985, Case for periodic, colossal jökulhlaups from Pleistocene glacial Lake Missoula: GSA Bulletin v.96, p.1271-1286.    "Yamhill County News-Register", online edition, June 18, 2005, "New Erratic Rock Marker Unveiled", by Yvette Saarinen.   

All Lewis and Clark quotations from Gary Moulton editions of the Lewis and Clark Journals, University of Nebraska Press, all attempts have been made to type the quotations exactly as in the Moulton editions, however typing errors introduced by this web author cannot be ruled out; location interpretation from variety of sources, including this website author.
/Regions/Places/missoula_floods.html
© 2017, Lyn Topinka, "ColumbiaRiverImages.com", All rights reserved.
Images are NOT to be downloaded from this website.
April 2016