Toured up 1300' above the car just below 9000' on the low angle slope leading up to Red Mountain Proper. Localized whoomping and cracking along the way. When we reached the higher angle base of the peak heard a long deep rumble and noticed propagating cracks above us. The largest propagation I've ever seen. Turned back. 100cm at the change over. Skiing down was deep and required straight-lining and dipping on and off the track to get out. Coverage was great, no rocks or wood on the way out.