Washington
Washington
Where the Palouse River meets the Snake River, Lyons Ferry State Park occupies one of the most geologically significant confluences on the Ice Age Floods trail. Tree-shaded green lawns slope to the cooling waters of the Snake and Palouse...
Where the Palouse River meets the Snake River, Lyons Ferry State Park occupies one of the most geologically significant confluences on the Ice Age Floods trail. Tree-shaded green lawns slope to the cooling waters of the Snake and Palouse Rivers at a spot where J Harlen Bretz discovered the giant gravel bars that proved the Snake River once ran backward during flood events. The park sits at the downstream end of Marmes Rockshelter, one of the oldest known sites of human habitation in North America, where 10,000-year-old remains were discovered in the 1960s. The surrounding terrain is classic scabland: basalt cliffs, deep flood-carved channels, and enormous gravel deposits testifying to the multiple flood paths that converged here before continuing westward to Wallula Gap. During the floods, water surging down the Snake from the south met water pouring through the scabland channels from the north, creating a massive zone of turbulence that deposited the gravel bars Bretz found so compelling. The park offers swimming, boating, and fishing in an extraordinary geological setting. It is the kind of place where you can relax on the beach and ponder the unimaginable.
Open year-round, day-use only. Discover Pass required. Located at the confluence of the Snake and Palouse rivers, about 15 miles north of Starbuck, Washington. 168 acres, 52,000 feet of shoreline, boat launches, swimming, picnic.
Lyons Ferry sits at the strategic outlet where Missoula floodwaters that overtopped the Cheney-Palouse scabland tract were funneled into the Snake River. As floodwaters topped the south valley wall of Washtucna Coulee, they exploited a weakened basalt fracture and rapidly cut the Palouse River canyon (the modern Palouse Falls drainage), draining into the Snake at exactly this confluence. The park is therefore at the outlet of one of the major flood-scour systems and on a slack-water terrace where flood gravels and rhythmites are exposed. From the bridge over the Snake, the Palouse canyon's discordance with the modern Palouse River drainage (the river is far too small to have cut its own canyon) is the visible signature of the floods. Active flood-cutting here occurred between 18.2 and 14 ka per the Balbas et al. (2017) chronology.
No site-specific peer-reviewed updates since the broader Cheney-Palouse tract synthesis in Waitt and O'Connor (2021).
The Palouse Falls Chapter (Pullman/Spokane region) is the IAFI affiliation for Lyons Ferry and Palouse Falls. Chapter field trips routinely visit both. IAFI/NPS interpretive panels are in place at the park.
Best April through October. Combine with Palouse Falls State Park 7 miles upstream, the falls are the headwall of the same flood-cut canyon. Avoid summer afternoons (open exposure, heat).
Three vantages no single photograph can hold, the same treatment that made Dry Falls legible.
Ground-level panoramas along the feature, so the scale of the flood landscape is something you stand inside.
An aerial reveals the geometry of catastrophe: scour, channels, and bars that are invisible at eye level.
A model of a key outcrop you can rotate and measure in the browser, the rock itself, on the page.
Capture window mid-June through mid-July 2026 · slots fill on this page as the campaign delivers.
Flood-extent overlay shows the maximum reach of the Missoula Floods.
The site in its place along the flood path, with the maximum flood extent drawn over the modern map.
View on the interactive map Cinematic timeline · 3D flood · every captured site