A Low Angle Detachment Landslide

Way back in 1972, I was a Geology student. As part of my degree, I needed to complete a summer of geologic mapping. As my university did not hold a summer field camp I applied and was accepted at Iowa State University for their summer field camp in Shell, Wyoming. The field work involved doing a lot of walking as each day we were handed an aerial photo several square miles or larger in size and were expected to complete a geologic map with correct formation contacts, folds, faults. At the end of the day were expected to turn in a completed map.

We also traveled to different areas to study unusual formations, one of which was the Heart Mountain Thrust fault outside of Cody, Wyoming. While there a Geologist with the United States Geologic survey talked about the Heart Mountain Thrust Fault. He explained how old rock formations could move on top of younger rock layers in a thrust fault. One of my fellow students, was attending Princeton, said that his professor said that the geologist was wrong . He said that he had learned that the mass of rocks had slid like an air hockey puck. Imagine a block of several thousand feet thick rock the size of Rhode Island moving at a speed of up to 700 miles per hole. The Geologist got angry as he had studied Heart Mountain and said that the idea was ridiculous. It turned out that the Geologist was wrong! If you want to see how it happened you need to go to YouTube and look up a presentation from Myron Cook on the Largest landslide the earth has ever seen, (well that we know)

On the second day of our trip we decided to drive the Chief Joesph Highway and enter Yellowstone National Park by the North East Entrance. This would allow us to travel backwards along the slide path and take some pictures… Now to really understand what you are seeing you need to watch the presentation. Thank you Myron Cook for your outstanding presentation! Clear skies Imagine a block of rock moving up to sixty mile, moving at 700 miles per hour and up to sixty mile away racing towards you! Pictured Heart Mountian, Dead Indian View, and the Sheep MountianBlocks thst moved from the sudden detachment.