Glacial Lake Missoula Simulator

Available now · Free · iOS

Watch an Ice Age lake fill, fail, and drain

Watch a roughly 1,800-cubic-mile Ice Age lake fill, fail, and drain — in your hand.

Between roughly 18,000 and 15,000 years ago, the Purcell Trench Lobe of the Cordilleran Ice Sheet blocked the Clark Fork River and impounded Glacial Lake Missoula. By volume, the lake was larger than today’s Lake Erie and Lake Ontario combined. When the ice dam failed, the resulting Missoula Floods carved the Channeled Scablands, raced down the Columbia River Gorge, and backflooded the Willamette Valley.

It happened dozens of times. Possibly more than a hundred. Glacial Lake Missoula Simulator lets you see it.

App Store link needed: replace [APP STORE URL: Glacial Lake Missoula Simulator] with the official App Store URL.

Interactive 3D map

Drag the elevation slider to watch the lake rise and fall across western Montana, snapping to reconstructed lake-surface elevations from about 2,067 feet up to a speculative 4,258-foot crest. Tilt into 3D mode, rotate bearing, and switch between Mapbox Outdoors, USGS Topo, and USGS Satellite basemaps.

Dam-break cinematic

Trigger a seven-stage automated sequence that walks through catastrophic failure: dam weakening, initial breach, peak discharge, main drainage through the Scablands, and slow re-damming.

Evidence gallery and context layers

Tap features and fly to them on the map: Mt. Jumbo and Mt. Sentinel strandlines, Camas Prairie giant current ripples, Cheney–Palouse and Telford–Crab Creek scabland tracts, Wallula Gap, the Columbia River Gorge, and Willamette Valley rhythmites.

Toggle ice sheets, regional lobes, drainage, flood routes, scabland tracts, the Columbia Gorge corridor, and Willamette backflood extent.

Honest about uncertainty

This is an interpretive visualization, not a survey-grade reconstruction. Every stand is tagged by confidence and evidence type. The app distinguishes well-documented strandlines from modeled upper bounds.

Sources and bibliography

Visible bibliography should include Pardee, Bretz, Baker, Atwater, Waitt, O’Connor & Baker, Smith, Dalton et al., USGS 3DEP, and USGS National Hydrography Dataset.

Bedrock cross-link

Want to read the ground beneath your own feet? Bedrock brings geology-first field awareness to the places you explore.