Reactive basal facets on Castle Peak.

Evidence of potential basal facet layer instability was limited to snowpit tests in this area (NW aspect, 8,860', open near treeline terrain). Basal facets on a poorly anchored slope (grass and small rocks) yielded repeatable, but fairly difficult to trigger propagation in large column tests. Strong snow temperature gradient lingers in the upper snowpack with near surface faceting occurring.

No obvious signs of instability observed while on tour in this area today. Recent wind slabs showed only very minor cracking, generally limited to areas previously undercut by another track. Significant skier traffic in this area had triggered no avalanches. Steeper slopes in the general vicinity of the snowpit tend to have more anchoring in the form of large rocks and down trees.

Photo 1: Post ECTP result, basal facet layer interface with the slab showing a small amount of downslope displacement.

Photo 2: Post ECTP result, Q3 sheer, but sudden collapse fracture character. Basal facet layer is just tall enough in this area to put overlying slab above available anchors.