Here is an email from the reporting party:

We found N facing slopes wind loaded with isolated, sensitive, low energy, shallow drifts. Turning our thoughts to south facing slopes we ski cut the upper S face and found well bonded new snow. We skied the upper 3-400 feet trending skiers left to the left most chute. Skier 1 waited in a rock outcrop on the left side of the line as skier 2 continued. The chosen chute ended in 50-75 feet of steep shallow snow mixed with exposed rock. Roughly 10-20 feet above the exposed rocks, a small slab (10 feet wide, didn’t get a good look at depth) pulled out sending skier 2 tomahawking through the rock band. Skier 1 skied to the crown, side stepped the rock out crop and was able to make verbal and visual contact with skier 2. Immediately after stepping off the rocks skier 1 released another shallow slab. Luckily this was funneled away from skier 2. On first assessment, skier 2 was noted to have severe chest/femur pain, difficulty breathing, a hole in his helmet, and blood seeping from the seat of his pants. In spite of the difficulty breathing and moving his injured leg he agreed to start heading down. Concern that his condition would deteriorate prompted skier 1 to call to EMS. They agreed to stand by as self-rescue was attempted (successfully). Big thanks to EMS/Alta ski for mobilizing and being willing to help, this could have turned out very differently.

Moral of the story: very shallow drifts are still big enough to take you for a ride, be careful