It looks like this likely was triggered by a small piece of cornice that fell from the ridge early this morning, gouged a small track in the chute, triggering some very shallow wind slabs along the way, and then triggered this slab across the endire apron once it hit the end of the chute. Lots of interesting layers where this stepped down, and where it triggered adjacent, shallower wind slabs. Old crowns still visible in the bed surface are interesting too.