Ice Age Floods
Ice Age Floods
National Geologic Trail
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Ice Age FloodsNational Geologic Trail Explorer

103Sites
174Routes
3,380Trail Miles
400Erratics
1,860Field Notes
4States
172Live Gauges
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Flood & Water
Geological Sites
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Exploration
Historical Research
🌊 Flood Comparison
Nearest Gauge --
Missoula Floods ~386,000,000 CFS
—
times today's flow
Current Conditions
Ephrata, WA
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Temperature
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Conditions
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Wind
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Humidity
Nearest River Gauge
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Station
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Flow (CFS)
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Stage (ft)
Today
During the Flood
Split View Activated

Drag the divider to compare today's landscape with floodwaters 15,000 years ago. Move the timeline slider to change the flood hour.

The Scale of the Missoula Floods
The largest known floods in Earth's history, triggered when a glacial ice dam broke catastrophically at the end of the last Ice Age.

Ice Age Floods National Geologic Trail

Explore the path of North America's greatest floods — from Glacial Lake Missoula across four states to the Pacific Ocean

3D Flood Simulation

Watch the catastrophic flood unfold hour by hour with the timeline slider

76 Geological Sites

Explore landforms carved by floodwaters — coulees, scablands, dry falls

174 Drivable Routes

Plan road trips along connecting routes, loops, and side trips

1,860 Historic Sites

See where J Harlen Bretz documented evidence a century ago

Getting Started
Use the layer panel to toggle data on and off — hover the info icons for descriptions
Use search to find specific sites, routes, or boulders by name
Press Play in the flood toolbar to animate the 48-hour flood timeline
Use Split View to compare today's landscape with the flood 15,000 years ago
Missoula Floods Timeline
Ice Dam Breach — Glacial Lake Missoula, ~15,000 years ago
Depicting one of ~100 flood events i
Dam Breach