Two of us on 2 old snowmobiles out for a quick trail ride, warm and very windy. I observed roller balls on the slope cuts from the road. On the road/trail we passed under 2 aspects that I observed wind loading. We approached the largest of the 3 hill cuts, I held back in a safe zone, my buddy crossed on the road below the slope, when he climbed his sled up and over the wind lip on the far side of the slope, it broke. 120' wide, 12"-36" deep. All the debris settled on the flat of the road.