Libby Creek canyon on the E. flank of the Medicine Bow Mountains near Centennial, Wyoming, is a site of well-developed and probably the most readily subdivided glacial deposits in the range. These deposits indicate that the range has been subjected to at least 2 separate Pleistocene glaciations, which are tentatively correlated with the Bull Lake and Pinedale glaciations described by Blackwelder in the Wind River Mountains of Wyoming. The Bull Lake(?) glaciation, oldest recognizable glaciation in the area, is represented by a single massive moraine characterized by subdued topography and quartzite-rich till. Pinedale(?) glaciation is represented by 3 well-developed sets of moraines, the 2 oldest of which are separated by a poorly developed moraine of an intermediate minor pulsation or stillstand. Deposits of the Pinedale(?) glaciation cover the greatest areal extent and are characterized by pronounced "knob-and-kettle" topography and tills rich in crystalline constituents. More recent deposits at the base of Medicine Bow Peak, W. of the source of Libby Creek, have been considered by some workers as recent moraines, but are more likely protalus ramparts overlying latest Pinedale till.