General December 13, 2019 Quote: Robert Frost, geohazards expert Not only sands and gravels Were once more on their travels, But gulping muddy gallons Great boulders off their balance Bumped heads together dully And started down the gully. Whole capes caked off in slices. I felt my standpoint shaken…
West Salt Creek rock avalanche viewed from the air General, Hazards, Publications May 16, 2017 AASG 2017 John C. Frye Memorial Award for CGS publication The Association of American State Geologists announced that their annual John C. Frye Memorial Award for 2017 is granted to the CGS and the staff members who authored the report The West Salt Creek Landslide: A Catastrophic Rockslide…
A close-up showing the scale of one of the blocks of Castle Rock Conglomerate that is already displaced Hazards July 10, 2009 Case Study: Rockfall – St. Francis of Assisi, Castle Rock The CGS studied the site of St. Francis of Assisi Church in Castle Rock extensively after a block detached from the upper cliff face in January 1981. The block presented a risk to homes at the base of the slope south of the church, and was subsequently broken up using…
Figure 3 -- This development in west Glenwood Springs constructed a rockfall impact wall above their townhomes to protect against both rockfall and mudslides (debris flows). Photo credit: Jon White for the CGS.|Figure 2 -- Several large rocks from the western wall of the Roaring Fork River in Glenwood Springs crashed into the houses below during the early morning causing significant damage Hazards July 6, 2005 Case Study: Rockfall – Glenwood Springs 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…
By August 2005 Hazards June 21, 2005 Case Study: Clear Creek Canyon rockslide Rockfalls and rock slides are common along transportation corridors in the Rocky Mountains. Clear Creek Canyon just west of Golden is one of the most active rockfall areas in Colorado. The canyon has been cut into Precambrian schists and gneisses by Clear Creek, one of the primary drainages in the…
Avalanche debris in the runout zone taken from a helicopter on the morning after the avalanche occurred Hazards March 24, 2003 Case Study: Avalanche – Silver Plume On March 23, 2003, a large avalanche occurred about one mile west of the Town of Silver Plume. The avalanche brought trees, rock, soil and snow to the valley floor, knocked down overhead utility lines, blocked the I-70 frontage road, damaged the town’s water treatment plant (WTP), and dammed Clear Creek. The dam was breached using explosives before the plant’s electric pump motors were flooded. With damage to the WTP’s chlorine contact tank and building, Silver Plum...
A precarious rock above Manitou Springs started to move in 1995 after a period of wet weather. As an emergency measure Hazards June 20, 1995 Case Study: Rockfall – Manitou Springs [ED: This report from 1995 was written by Jon White, (Senior Engineering Geologist, Emeritus). It looks at a specific rockfall situation in the central Front Range town. ] Manitou Springs occupies a narrow valley where Fountain Creek emerges from the foothills northeast of Pikes Peak and west of Colorado Springs. The valley slopes are composed of interbedded resistant sandstone and conglomerates (i.e., gravelly sandstone), and weaker mudstones and shale. The outc...