Glen Tilt -- a classic glacial trough

Glen Tilt in Perthshire is a classic U-shaped glacial trough -- except that it isn't really typical of glacial troughs at all.  It's a long, straight through valley, cut along the line of a fault, and for at least some of the time the whole valley was submerged beneath an ice sheet, with ice moving across it at an angle.  So the trough might have contained stagnant ice at that time.  But its shape reveals that it has clearly carried streaming ice at other stages of the Ice Ages, just like some of the through valleys of Greenland.