This is an old avalanche involving wind-drifted snow. The occurrence date is an estimate. This looks very similar to the avalanche I observed in the Horse Creek Chutes. Aspect, Elevation, and the shape of the terrain are all very similar. My guess is that this slide occurred at the same time as the Horse Creek Chute slide. Vertical is unknown because I couldn't identify the crown of this old avalanche. It most likely initiated up in the rocks directly above the debris pile, or above and to the looker's right.

8" of snow fell on 12/23. NW winds kicked up early in the morning on 12/24 and blew in the moderate to strong range through 12/26. The slide most likely occurred during this time.