Wallula Gap
What is it and why visit?
Wallula Gap is famous as the constriction where the massive
The scenic site was designated a National Natural Landmark in 1980 and is an important stop for anybody seeking to understand the true magnitude of the ice age floods and their impact on the Pacific Northwest. It is a site not only well-suited to imagining the floods but also a place to enjoy the beauty of the present-day landscape of the Columbia basin.
Geologic Story
Wallula Gap is a narrow point in the Columbia River measuring just over 1 mile across. It formed as the Columbia River cut down through the surrounding lava flows of the
more than seven thousand times higher than the flow of Niagara Falls
The gap could initially accommodate only about half of the raging flood waters, damming the floods to form temporary Lake Lewis. The depth of the lake reached 1,200 feet as the waters struggled to push through the gap. Imagine standing on the hills above Wallula Gap while about 740 million cubic feet of water stream by every second, flowing at rates of up to 50 miles per hour. This rate is more than seven thousand times higher than the flow of Niagara Falls, which is estimated at about 100,000 cubic feet of water per second.
A geologic feature worth seeing at Wallula Gap is the Twin Sisters, two basalt lava flow buttes carved out by the floodwaters. The upper half of each butte is the upper, faster-cooling entablature portion of the lava flow, whereas the base of each butte is the inner, slower-cooling colonnade section, where thicker hexagonal columns form as a result of the cooling process.
This site is a National Natural Landmark. The National Natural Landmarks Program recognizes and encourages the conservation of sites that contain outstanding biological and geological resources.
LEARN MORE ABOUT:
See the Nick on the Rocks video below to learn more about Wallula Gap, Lake Lewis, and the ice age floods!
Fun Fact
The waters of Lake Wallula, formed by the construction of McNary Dam in 1957, hide the submerged ruins of old settlements. As a result of this dam-related flooding, the town of Wallula was relocated to a site just northeast of where it had been historically.
What to see and do
Access passes you may need: None
Click here to open full sized image
Getting there
There is no official Wallula Gap visitor’s center but there is an overlook, with access to the Twin Sisters. This overlook is located just off State Route 730. There is a small gravel parking area at the base of the butte.
Nearby amenities
Photo gallery
Bibliography
Benito, Gerardo; O'Connor, J. E., 2003, Number and size of last-glacial Missoula floods in the Columbia River valley between the Pasco Basin, Washington, and Portland, Oregon: Geological Society of America Bulletin, vol. 115, no. 5, p. 624–638. [https://doi.org/10.1130/0016-7606(2003)115<0624:NASOLM>2.0.CO;2]
Carson, R., J.; Pogue, K., R., 1996, Flood Basalts and Glacier Floods: Roadside Geology of Parts of Walla Walla, Franklin, and Columbia Counties, Washington: Washington Division of Geology and Earth Resources, Information Circular 90, p. 47.
Oregon Historical Society, Fort Nez Perce [webpage]: The Oregon History Project. [accessed Sept. 7, 2017 at https://oregonhistoryproject.org/articles/historical-records/fort-nez-perce/#.WbG7kz6GOJA ]
Niagara Falls State Park, Facts about Niagara Falls [webpage]: Niagara Falls State Park. [accessed Sept. 7, 2017 at https://www.niagarafallsstatepark.com/niagara-falls-state-park/amazing-niagara-facts ]
Popejoy, Don, 2000, The Great Columbia River: Lewis and Clark Trail Heritage Foundation, Washington State Chapter, April 2000 Newsletter. [accessed Sept. 8, 2017 at http://wa-lcthf.org/newsletters/pdf/2000_04_news.pdf ]
Cascades Volcano Observatory, The Volcanoes of Lewis and Clark, October 19, 1805, Down the "Great" Columbia River - Spring Gulch to Umatilla [webpage]: U.S. Geological Survey. [accessed Sept. 7, 2017 at https://volcanoes.usgs.gov/observatories/cvo/Historical/LewisClark/volcanoes_lewis_clark_october_19_1805.shtml ]
Walla Walla, Welcome to the Wallula history website [website]: Walla Walla 2020. [accessed Sept. 7, 2017 at http://ww2020.net/historic-sites/wallula/ ]