Mark Staples is standing where the party triggered the avalanche. It broke another 50 feet higher and was 1 to 1.5 feet deep and 40 feet wide. As the slide moved downhill it released slopes on the side of the gully adding to the volume to avalanche. The slide was a hard slab of wind blown snow.
Forecast link: GNFAC Avalanche Forecast for Sat Dec 12, 2009