for those not familiar with tree wells
Tree wells I wonder how many times it is due to the skier or snowboarder passing over an the unseen roof (like a snow bridge) that collapses into a unseen well that has a larger circumference around the tree than one imagines? (Kinda like on glaciers, it's the crevasses you don't see that are the problem.)
You would think the vast majority are like that, because otherwise it would be people just careening out of control into obvious holes.
