A skier remotely triggered this in Pebble Creek, YNP. It propagated wide (around 200'), with a 1-3' crown, running a short distance. The skier assumed the weak layer to be buried surface hoar and small grained facets in combination with a m/f crust. The roll-over was probably 40 degrees, but lower angle slopes also surprised me with movement (30 degrees). Photo: Beau Fredlund