PRECONSOLIDATION PRESSURES IN THE BATTLEFORD FORMATION, SOUTHERN SASKATCHEWAN, CANADA

Soft, surficial, unoxidized till of the Battleford Formation overlies hard, oxidized and unoxidized till of the Floral Formation. The difference in hardness between these two formations is the result of preconsolidation pressures that range from 1500 to 2200 kPa in the Floral Formation and from 350 to 750 kPa in the lower till unit of the Battleford Formation. The upper till and clay unit of the Battleford Formation, which represents a conformable contact between this formation and the overlying glaciolacustrine clay, is normally consolidated. Preconsolidation of the Floral Formation apparently took place upglacier where the potentiometric surface for subglacial beds was 170-240 m below the ice surface. The lower till unit of the Battleford Formation was deposited from and consolidated under stagnant ice. The upper normally consolidated till and clay unit of the Battleford Formation was let down upon the lower till unit by ablation. The calculated minimum stagnant ice thickness required for consolidation of the lower till unit of the Battleford Formation ranges from 51 to 81 m. The calculated time required for consolidation is less than 100 years.