Ice Age Floods National Geologic Trail
Ice Age Floods National Geologic Trail
The Corfu Slide is one of the largest landslide complexes in Washington state, a massive slump of earth and basalt along the Columbia River that was likely triggered by the Ice Age Floods systematically undercutting the base of the hillside over dozens of flood cycles....
The Corfu Slide is one of the largest landslide complexes in Washington state, a massive slump of earth and basalt along the Columbia River that was likely triggered by the Ice Age Floods systematically undercutting the base of the hillside over dozens of flood cycles. Stretching roughly three miles along the river in Grant County, the slide displaced millions of cubic yards of material as saturated basalt cliffs gave way under their own weight after floodwaters receded. The hummocky, chaotic terrain visible today -- with its tilted basalt blocks, sag ponds, and disrupted drainage patterns -- tells the story of catastrophic slope failure on a scale that dwarfs modern landslides. During the floods themselves, water depths in this area may have exceeded 800 feet, creating enormous hydraulic pressure against the canyon walls. The rapid draining after each flood event would have removed the water's support like pulling a rug from beneath the cliffs. Geologists study the Corfu Slide as a textbook example of how megafloods reshape landscapes not just through erosion but through the destabilization they leave behind.
The Corfu Slide is on BLM-managed land on the north slope of the Saddle Mountains in Grant County, Washington. Access is via gravel Corfu Road off Highway 26 west of Othello, leading roughly 5–7 miles up to a "Saddle Mountains Overlook" parking area near the head scarp; the final road is unmaintained, best for high-clearance vehicles, and there are no facilities or interpretive panels on site. It is open year-round but exposed and remote.
The Corfu Slide is a complex of roughly 24 individual basalt landslides covering 18–20 km² above Crab Creek, with about 1 km³ of displaced material. Most analyses attribute initiation to undercutting of the mountain face by Missoula floodwaters that split west of Sentinel Gap and impinged on the north flank of the Saddle Mountains. Failure planes appear to follow weak clay-rich interbeds within the Columbia River Basalt Group. The repeated slides are interpreted as having been triggered or progressively worsened across multiple flood cycles during the 18.2–14 ka megaflood window. NASA researchers have studied the complex as a terrestrial analog to large landslides on Mars.
Geologic interpretation has remained largely consistent with Bjornstad and others' synthesis work; no major reinterpretation has been published since the Balbas et al. 2017 chronology refined flood timing. No updates found since the 2017 cosmogenic-dating framework.
The Ice Age Floods Institute features the Corfu Slide on its site-list pages and includes it in regional Wenatchee/Ellensburg chapter field-trip itineraries (e.g., the EWU Wenatchee field-trip publication). There is no on-site IAFI panel or named partnership at the overlook.
Best visited in spring or fall; midsummer is hot and shadeless. The drive is the attraction — a vehicle pull-up and short walk to the head scarp give a panoramic view down on the slide complex and across Crab Creek toward Saddle Gap.
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.