Luke (nephew) examines geocache contents while sitting on ice-rafted erratic boulder (Rattlesnake Mountain in distance).

The argillite boulders (pictured above) consist of material that was part of an ancient seabed more than a billion years ago and later involved in the uplift of the Rocky Mountains. During the most recent Ice Age, the rocks became trapped within glacial ice in British Columbia or northern Idaho. That ice was picked up and carried into the Pasco Basin by an Ice Age Flood from Glacial Lake Missoula. Note: B.C. material would have been moved south within glacial ice - Into the path of Lake Missoula floodwaters.

NASA images show path of the Ice Age Floods

- Click to enlarge satellite image -

Google Earth and Google Maps are excellent tools for anyone wishing to explore the Ice Age Floods region.



Pasco Basin Pea Harvest Following development of the Columbia Basin Irrigation Project and other systems, the area once inundated by the waters of Lake Lewis encompasses some of the most productive farmland in the world. Slackwater flood sediments mixed with windblown deposits combine to create fertile well-drained soils with the capacity to produce high value crops. Channels cut by the Ice Age Floods created the opportunity to store and move irrigation water.

Columbia Gorge WALLS OF WATER THEN RAGE THROUGH THE COLUMBIA GORGE Water volumes exceeded the capacity of the gorge near today's John Day Dam, creating another impoundment which backflooded into the Dalles and Umatilla basins. Surging water gouged the walls of the gorge to their modern near-vertical alignment, thereby creating the complex of waterfalls at the gorge's west end. Patches of scabland were created near the Dalles and extensive sand and gravel bars were dropped into the valleys of tributary streams. THE FLOODS RUSH TO THE OCEAN, WHILE BRIEFLY DROWNING THE WILLAMETTE VALLEY Another check point at Kalama caused the floods to form another temporary lake which flooded the Willamette Valley as far south as Eugene, Ore. Large lowland tracts in Washington across the river from Portland also were underwater. The flood crests then dropped rapidly as they reached Astoria and the Ice-Age seacoast 40 miles west of that modern city. Flood debris has accumulated to a depth of 800 feet in the Columbia River's bed west of Astoria. Multnomah Falls Many spectacular waterfalls are found in the Columbia Gorge. The steep walls of the gorge were shaped by Ice Age Floods.

A large iceberg carried the Bellevue Erratic over Eastern Washington and down the Columbia Gorge during one of the largest Ice Age Floods. The iceberg then drifted into the flooded Willamette Valley where it grounded on hillside, standing this 40-ton erratic southwest of Portland, OR.

ICE AGE FLOODS MYSTERY The idea of catastrophic flooding ran counter to the conventional wisdom of scientists, but over a 30-year period geologist J Harlen Bretz proved that the remarkable natural features of the Columbia Basin could only have occurred in this way. Fellow geologist Joseph T. Pardee identified the role of Lake Missoula in the process.

Diverse habitats within the flood region are home to a wide variety of plants and wildlife. Mission Valley elk (MT), Drumheller Channels rattlesnake (WA), Columbia Basin wildflowers (WA).