At the bottom of East Greeley at Alta we saw a small (10-15 feet tall), but obviously wind-loaded rollover. Skiing on top of the rollover to descend a lower angle side of the slope triggered the slide one foot below and to the side of me. It ended up being about 15-20 feet wide wind slab, and about 16 inches deep. Seems to have broken at the new snow / old snow interface. The bed surface near the crown was 41 degrees.