Ice Age Floods National Geologic Trail
Ice Age Floods National Geologic Trail
Mount Pisgah overlooks the southernmost reach of the Missoula Floods in the Willamette Valley, near Eugene, Oregon -- some 500 miles from the ice dam that triggered the deluge. When the floods poured through the Columbia Gorge and spread across the Portland Basin, they backed up...
Mount Pisgah overlooks the southernmost reach of the Missoula Floods in the Willamette Valley, near Eugene, Oregon -- some 500 miles from the ice dam that triggered the deluge. When the floods poured through the Columbia Gorge and spread across the Portland Basin, they backed up into the Willamette Valley behind the constriction at the Kalama Gap, creating temporary Glacial Lake Allison. The lake filled the valley to approximately 400 feet above modern sea level, reaching this far south and depositing fine silts, clays, and scattered glacial erratics carried on icebergs from as far away as northern Idaho and Montana. From Mount Pisgah's summit trails, you look out across the flat valley floor -- every acre of that productive farmland owes its fertile soil to sediments deposited by floodwaters that traveled from Montana. The mountain itself stood as an island in Glacial Lake Allison, its forested slopes rising above the turbid water. The view from the top makes the scope of the floods suddenly tangible: everything below the 400-foot elevation line was underwater, a temporary lake the size of a small sea, created in days and drained in weeks.
This is Mount Pisgah at the Howard Buford Recreation Area near Eugene, Oregon (the only Mount Pisgah within the Missoula Flood inundation footprint with an Ice Age Floods relevance). Open year-round, day-use only. $4 parking fee (Lane County). 2,200-acre county park with ~30 miles of trails, 1,518-foot summit, includes the 209-acre nonprofit Mount Pisgah Arboretum.
Mount Pisgah is at the southern end of the Missoula Flood inundation in the Willamette Valley. When Missoula floodwaters were backed up by the Kalama Narrows constriction near Portland, they ponded as temporary Lake Allison across the Willamette Valley to elevations of roughly 400 feet asl. At that high stand, the floodwater reached as far south as Eugene; Mount Pisgah (1,518 ft) stood as an island well above the lake surface. Ice-rafted erratics — most famously the Bellevue Erratic near McMinnville (40 tons, 200 miles from the nearest matching bedrock in Montana/Idaho) — are scattered across the Willamette Valley floor and along the foothills around Mount Pisgah at the 400-foot contour. The valley's deep agricultural soils are largely flood-deposited Willamette Silt. Mount Pisgah's role is as a "high-water reference island" rather than a high-energy scour site — visiting the summit makes the scale of Lake Allison legible.
No site-specific updates since O'Connor et al. (2001, USGS Open-File 01-46) on the Lake Allison flood-pond record. Balbas et al. (2017) chronology applies to the upstream sources. Willamette Valley erratic inventories continue through the Willamette Meteorite Society and the Tualatin Ice Age Trails project.
The Lower Columbia/Willamette area is covered by the Willamette Valley Pleistocene Project (a Tualatin-based citizen-science group), not a dedicated IAFI chapter. The City of Tualatin holds an NPS-designated formal partner-community status — Mount Pisgah is one of the southernmost stops on Tualatin-led tours.
Best April through October; summit views east to the Cascades and north up the Willamette Valley are the main draw. The 1.5-mile summit trail (300 feet elevation gain) ends at a bronze relief map indicating regional features. The Arboretum (lower elevation) is a separate, easier visit.
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.