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Teach the science without dumbing it down
The map draws on the same data IAFI, USGS, and four state geological surveys trust, navigable by someone who has never heard of a megaflood.
Ice Age Floods National Geologic Trail
Ice Age Floods National Geologic Trail
For roughly four thousand years, dozens of catastrophic outburst floods from glacial Lake Missoula carved the Pacific Northwest. The largest, dated to 18.2 ka, moved ten times the combined flow of every river on Earth. Walk the ground the water carved: this is the public home of the Ice Age Floods National Geologic Trail, built on the science of the Ice Age Floods Institute and four state geological surveys, with immersive 360° capture so you can stand inside the story from anywhere.
A 2,000-foot-tall ice dam held back a lake the size of Lake Erie. When it failed, ~500 cubic miles of water emptied in 48 hours, scouring a quarter of Washington State down to bedrock. It happened dozens of times.
Most signs and pamphlets along the trail still say “15,000 years ago.” That number is 1920s science, Bretz’s best estimate from indirect stratigraphic evidence, the only tool he had.
In 2017, a team led by Andrea Balbas (with Vic Baker, Bruce Bjornstad, and others) did what no one had managed before: directly dated the flood-deposited boulders. Using ¹⁰Be cosmogenic exposure dating on 32 new samples (plus 13 recalibrated prior ages) across Washington, Idaho, and Montana, they re-anchored the chronology.
The largest Missoula Floods happened at 18.2 ± 1.5 ka (about three thousand years earlier than the inherited shorthand) and the floods continued in dozens of separate events until roughly 14 ka. Their paper also flipped a long-standing assumption: the largest floods routed down the upper Columbia, not through the Channeled Scabland. The Scabland features record the later, smaller events.
Read the Balbas et al. 2017 page →Granite from the Idaho Batholith. Quartzite from northern Washington. Gabbro from the Belt Supergroup. Each ice-rafted erratic in the Willamette Valley is a depth gauge for a single flood event: a boulder frozen into an iceberg, floated up the Columbia, and stranded across western Oregon when the floodwaters drained.
2.4 × 1.6 × 1.0 ft boulder bearing glacial striations. Origin: the Idaho Batholith, hundreds of miles away. Cataloged by Arthur Piper, USGS, June 1929.
A coarse-crystalline mafic boulder: the lithology points to the Belt Supergroup of northern Montana, transported in glacial ice across four states.
Quartzose sedimentary or metasedimentary boulder, sourced from northern Washington or southern British Columbia. Floated south by an iceberg the size of a building.
Large feldspar phenocrysts make this boulder distinctive: a textbook Idaho Batholith specimen, now sitting 400 miles from where it was quarried by ice.
Varied composition suggests this boulder was caught up in a slurry of frozen sediment: an iceberg with a cargo of every rock the floods touched on the way through.
Every documented Willamette Valley erratic has a detail page: lithology, elevation, original field notes, and a flood-extent mini-map. Filter by lithology, elevation, or surveyor.
Field records from Arthur Piper’s 1928–1929 USGS Willamette Valley survey · integrated and enhanced by the Ice Age Floods Institute and Terrain360.
For forty years the geological community rejected the flood hypothesis. The reason they eventually accepted it was the field record: 1,857 field sites cataloged by J Harlen Bretz and his successors, each a precise written description of the ground. Every one of those records is now a detail page on this site.
“Brown’s Butte is a quartzite Hill projecting... on summit of saddle east.... north slope..erratics above 2500…”
“This tract, between NPRR on west and Latah Creek on east bears scattered granites…”
“A pit opened on base of southwest side of this hill... exposes poorly sorted…”
“At Marshall is a delta front, opened by a gravel pit in the west wall…”
“Cuts on Yellowstone Trail (now I90) show basalt in two places.... basalt is columnar…”
Every Bretz-era field site has a detail page with the original notebook entry, the modern context that vindicated the work, a flood-extent mini-map, and capture-roadmap slots for 360°, drone, and 3D imagery.
The Ice Age Floods reshaped a region that is, and has always been, the homeland of many tribal nations, nations who live here today. The floods are part of their country, and the peoples of this land carry their own accounts of the water and the ground it remade. A dedicated page shares those accounts in the words of tribal speakers themselves. This is only the doorway to it.
Live interactive map with cinematic flood reconstruction, 3D water-extent timeline, before/after split view, and direct entry into every captured site. Powered by Terrain360.
iceagefloodstrail.org/map/ with 301 redirect once Phase 1 commits
The map is a custom 3D experience: a cinematic flood reconstruction, layered geologic data, and over 2,500 indexed points from IAFI, USGS, and four state geological surveys. Here is what you can do with it.
An east-to-west camera sequence follows the floodpath from the ice dam breach to the Pacific. It plays on your first visit, and you can replay it anytime.
Drag the timeline slider and watch the water’s extent rebuild hour by hour after the dam failed. The flood fills the landscape as you move.
Drag a split view to see the same place as it looks today, then as it looked under 500 cubic miles of water.
Six cards put the flood’s scale into frames you know: ten Mississippis, fifty Niagaras, a wall of water taller than the Space Needle.
Open eleven data layers and filter by type, state, and route. Jump to any of the 103 sites or 1,860 IAFI field locations.
Bottom-sheet panels, lazy-loaded layers, and a help button that walks first-time visitors through the timeline and split view.
These trails are captured and live right now, from the Blackfoot River in Montana, the flood source, to the Columbia Gorge, the Channeled Scablands, and Palouse Falls. Start here, then follow the floods across four states.
Five hundred immersive scenes wrapping the Dry Falls plunge basin, the world’s largest dry waterfall, four times the width of Niagara.
View profile →Eleven miles along the Blackfoot River corridor in the heart of Glacial Lake Missoula territory, the lake whose 2,000-foot ice dam, when it failed, became the floods themselves.
Open in Terrain360 →The 360° capture, the geology, the field-note record, and the IAFI source data, all in one place. Here is one.
The largest waterfall on Earth, now dry. Five hundred immersive scenes wrap the plunge basin where the floods carved a 3.5-mile-wide cataract four times the width of Niagara. The full page brings together the 360° capture, geologic context, J Harlen Bretz commentary, IAFI source data, and visitor information.
See the full pageEvery IAFI chapter is a learning hub: field trips, monthly lectures, school outreach. This site does that work at national reach.
The 360° capture lets your class walk the trail, the plunge basin at Dry Falls, the Blackfoot corridor, without a bus.
Every site, erratic, and field note is a detail page: a free, citable reference for students and teachers in any state.
The detail pages connect to the National Park Service’s “Investigating Ice Age Floods, A Teacher’s Guide,” the curriculum guide for the trail, so lesson plans link straight to the places they describe.
A wall of water taller than a skyscraper crossed four states, dozens of times, and remade a corner of the continent. It is some of the clearest evidence of catastrophic geology anywhere on Earth, and most of the people who live on top of it never heard the story in school. These four ideas are why telling it well matters.
The map draws on the same data IAFI, USGS, and four state geological surveys trust, navigable by someone who has never heard of a megaflood.
A chapter field trip reaches its local school. The digital trail reaches a classroom anywhere, for students who will never make the drive.
Each chapter’s local expertise, surfaced to a national public it could never physically host.
The 360°, drone, and photogrammetry capture is a time-stamped teaching and research record as the landscape keeps changing.
From decades of field science to a national classroom: the floods story, finally taught.
Questions, content corrections, chapter integration, partnership ideas: contact Ryan Abrahamsen, Terrain360 founder.
ryan@terrain360.com · 804.677.1456
James O’Connor (USGS) · Bruce Bjornstad · Stacy Warren (EWU) · Dan Coe (WGS) · Lloyd Dekay (IAFI Lower Columbia) · Jeffrey Becklund (IAFI Wenatchee) · Glenn Cruickshank · Justin Radford (NPS).