From the resort's blog:
Sometime in the morning of March 10, 2011 prior to 0815 a large avalanche ran through the Clark side of Heather Canyon. The slide scoured the sides of the drainage, deposited a significant amount of debris in the gut which extended well past the confluence of the Clark/Heather drainages and the bottom terminal of the Heather Chair.
The track and debris extend to historical trim lines. Further investigation is underway. The origin of the slide is unknown at this time. There are no known casualties or structural damages at this time. The Canyon will remain closed until further notice. We ask that only authorized personnel access the Canyon – please respect all closures.