Ice Age Floods National Geologic Trail
Ice Age Floods National Geologic Trail
The Waterville Plateau near Sims Corner is an open-air museum of glacial landforms, preserving some of the finest eskers and kames in the Pacific Northwest. Eskers -- sinuous ridges of sand and gravel deposited by rivers flowing through tunnels beneath the ice sheet -- snake...
The Waterville Plateau near Sims Corner is an open-air museum of glacial landforms, preserving some of the finest eskers and kames in the Pacific Northwest. Eskers -- sinuous ridges of sand and gravel deposited by rivers flowing through tunnels beneath the ice sheet -- snake across the plateau like frozen rivers, some stretching for miles. Kames, cone-shaped hills of debris deposited where meltwater poured through holes in the ice, dot the landscape alongside scattered glacial erratics -- boulders carried hundreds of miles from Canada and dropped here as the ice melted. These features were created by the Okanogan Lobe of the Cordilleran Ice Sheet during its retreat, and their remarkable preservation owes much to the semi-arid climate that has protected them from erosion for over 13,000 years. Together with the nearby Withrow Moraine, this site provides an extraordinary record of how a massive glacier lived and died on this plateau. The rolling wheat fields around Sims Corner hide a landscape shaped entirely by ice, and every ridge and hillock tells part of the story.
The site is a National Natural Landmark (designated 1986) on the Waterville Plateau in Douglas County, Washington, north of the towns of Mansfield and Sims Corner. It sits on a mix of public and private rangeland; there is no formal park, visitor center, or signed trail. Most viewing is from State Route 172 and adjacent county roads — visitors should respect property lines and the working-ranch setting.
Sims Corner is primarily a glacial-deposition site rather than a flood-erosion site, and that distinction matters. The eskers, kames, kettles, terminal moraines, and erratics here record stagnation of the Okanogan Lobe of the Cordilleran Ice Sheet at the southernmost extent of glaciation on the Columbia Plateau. The same ice mass that built these features also diverted the Columbia River south into Moses Coulee and later Grand Coulee, setting up the routes the Missoula Floods would exploit. Floodwaters from Glacial Lake Missoula did not directly scour the Sims Corner plateau, but the landforms preserved here are part of the same Pleistocene system. The site is included on the Ice Age Floods National Geologic Trail as a complement to the flood-erosion landscapes downslope at Moses Coulee and Grand Coulee.
No site-specific updates found since the original NNL evaluation. Regional cosmogenic-dating work on the Okanogan Lobe and the megaflood chronology (Balbas et al. 2017; Hanson et al. 2020) anchors the largest northwestern Columbia floods at roughly 18.2 ka but does not target Sims Corner directly.
No dedicated chapter, panel, or named partnership located. The Wenatchee Valley Erratics Chapter is the nearest IAFI chapter to the Waterville Plateau and occasionally references the area on regional field outings.
Late spring through early fall is the practical window — winter roads can be drifted closed, and summer heat on the plateau is severe. Plan it as a driving loop combining Sims Corner with Moses Coulee, McNeil Canyon Haystack Rocks, and Boulder Park; expect minimal interpretive signage and no services.
Every site along the trail will receive the full Terrain360 capture treatment: ground-level 360° panoramas, drone aerial imagery, and photogrammetry-based 3D models that visitors can spin in their browser. This page reserves the slots; the imagery flows in as field capture completes.
Ground-level 360° panorama, every step along the feature, captured by Terrain360 field crews.
Drone flyovers reveal the geometry of catastrophe — ripple marks, gravel bars, and scour patterns invisible from the ground.
Photogrammetry and Gaussian-splat models let visitors rotate, measure, and inspect features in detail-page WebGL viewers.