Case Study: Rockfall – Glenwood Springs
2005-07-06 | Dr. John Hopkins
The town of Glenwood Springs in west-central Colorado lies at the confluence of the Roaring Fork and Colorado rivers. The town is tightly constrained by the steep river valleys so land-development pressure is causing residential growth to push into rockfall hazard areas. In West Glenwood, on the west side of the Roaring Fork River, the valley is rimmed with dipping sandstone outcrops of reddish Maroon Formation (Figure 1).
The sandstone layers are being undercut by the erosion of underlying softer siltstone and shale so that large sandstone blocks are being actively undermined and destabilized. In this area, there have been several large rockfall events from the valley rim; some that have severely damaged homes on the valley floor, 1,100 vertical feet below (Figure 2). Fortunately, there have been no injuries or fatalities. While there has been rockfall mitigation in some locations (Figure 3), the threat remains in other areas.
For more on rockfall issues around the state, see the original RockTalk: Rockfall in Colorado.