Buildings designed for snowy environments have pitched roofs to stop too much snow accumulating.  It can gradually shear off the building, sometimes in the form of snow sheets and sometimes, courtesy of some melting, as giant icicles.  Wandering around the buildings in Jackson and Yellowstone, I was taken by the large sheets of snow and ice.  The visitors’ center at Yellowstone had a particularly large amount of snow drifting off the roof and obscuring the view out of some of the windows.  Other icicles looked rather precarious and, if you should find yourself beneath them when they fall, it could be detrimental to your health!