Thistle dumped a 150-foot wide mud pile that dammed a river and buried an entire town. Olson said Bear Wallow is 2.3 times bigger. Rex Harris, the UDOT engineer in 1999 who had the job of stopping the slide, agreed. At its shallowest it is 30 feet deep and it goes down to 100 feet. The slides move because subsurface water oozes through the dirt and forces its way up.
Gravity pulls the dirt downhill.
Measurements show Bear Wallow is slipping at a rate of 6 inches a year. DeYoung said the spring runoff, and water soaking the mountain, is causing this slide. We had no indication that this is an area that would move on us, but this time of year with the saturated soil, this is the time of year that sort of thing will show up. When the road will reopen depends on how long repairs take, he said. He said repairs to the road surface can't be started until the cause of the sliding is found and fixed.