While descending and slope cutting this popular area just outside of the Brighton Boundary area we intentionally triggered what appeared to be a small section of snow that had not previously been cut out by the preceding rider through the area. Cutting right the slope released at the new snow/old snow interface from the last two storms. It immediately wrapped left around a rock band and stepped down below the one finger bed surface. Collapse failure occurred below this crust and it propagated 350 feet to the riders left. The crown propagated upslope to the left at least 85 feet higher in steeper untraveled terrain, and then the propagation followed the contours of the terrain and descended about 350 feet to the left. The slope cutter was never in danger moving to the right and on lower angle terrain. Upon inspection of the crown face it became apparent that the slide stepped down. The initial release point was on a slope that has seen a lot of traffic. The propagation area also has seen traffic. We were the only people in the area at this time. The slope ran to the transition/bench below and the debris fanned out as it came down and wrapped around a large feature. There was 16 inches of fist (new snow from the last two events), then one inch of one finger, two inches of intermediate facets, then one inch of one finger, and then at least 4 inches of advanced facets. Below this faceted layer was the bed surface of the step down and this layer was pencil hard. There were areas where the total depth was 3 feet. Further South on the same ridge line there was another rider triggered slide on a similar aspect. This one was at least 180 feet wide, maybe more. I only got a look at it after descending much later in the day and the light was poor. Reports from the Brighton Patrol indicated the slide was reported and all were safe. I do not have any other details. This slide broke out on a steep rock/cliff ledge.