I think this was the outrageously steep gully slope that I slipped on, trying to climb up it, by kicking steps into the volcanic scree, one step at a time. Near the top, it all gave way, and I instinctively rotated my body around so I could plop down on my posterior, where it would be easier to arrest myself by digging my feet into the scree. The impact jarred a water bottle loose and I watched it tumble down to the ice field below. Well, I had plenty more water stowed securely way in my backpack.