RED DEER HILL - A DRUMLINIZED, GLACIOTECTONIC FEATURE NEAR PRINCE-ALBERT, SASKATCHEWAN, CANADA

Red Deer Hill is 5 km long, 3 km wide, and 70 m high. The hill is a gl aciotectonic structure formed by a single 106 m thick thrust block, pr esumably derived from the 80 m deep, upglacier Holmes depression. The thrust block became dislodged by displacement along a presheared horiz ontal gouge zone where the shearing resistance of the clay was reduced to a residual state by the first (Mennon) glaciation. The hill-depres sion structure was formed by the Battleford glacier, which drumlinized Red Deer Hill before depositing a veneer of till over the structure. The Holmes depression was filled with glacial Lake Saskatchewan lacust rine and deltaic sediments. Horizontal displacement along a decollemen t in the direction of the activating force resulted in a stress enviro nment changing from extension to compression. In the zone of extension (Holmes depression), an active Rankine state developed and beds stret ched and thinned. In the zone of compression (Red Deer Hill), converse ly, a passive Rankine state developed and the beds resisted compressio n and thickened. Drumlinization of the thrust block occurred as latera l pressures in the block mass changed from passive (stoss slope) to ac tive (lee slope) downglacier.