The topographic features to which attention is here chiefly invited have been defined by G. K. Gilbert* as follows:
“A hanging valley is a small U-shaped tributary to a larger valley, the floor of the smaller being considerably higher at the junction than the floor of the larger. Many of them are short, high-grade troughs, heading in cirques; some are mere cirques, without troughs—spoon-bowl hollows, high on the walls of main valleys. They are associated with other evidences of glacial sculpture, and the elevation of their floors is believed to result, as a rule, from the unequal erosion of valleys by glaciers of unequal size.”
The first of these definitions restricts . . .