Effects of glaciations upon karst aquifers in Canada

In Canada there are ∼5.7 · 105 km2 of limestone and marble outcrop, ∼6 · 105 km2 of dolomite and ∼8 · 104 km2 of sulfate rocks. In addition, halite subscrops beneath 5 · 105 km2 of the central Prairie region and interacts with modern groundwater circulation to a varying extent. More than 90% of the total outcrop-subcrop has been repeatedly glaciated. The most recent glaciation (Late Wisconsin) terminated 13,000–5000 yrs. B.P. in different areas. Carbonate terrains still partly buried by glacier ice may be inspected in the Rocky Mountains.Nine distinct effects of glacial action upon the propagation and efficiency of karst aquifers are recognized. Destructive effects include erasure, dissection, infilling and injection. Bedrock solution may be inhibited during non-glacial periods by a cover of glacial drift rich in carbonate clasts. Glacial burial may also preserve an aquifer and enhance its storage characteristics. Aquifer expansion may be stimulated by raising the hydrostatic head or steepening hydraulic gradients, or by crustal flexure during deglacial isostatic rebound. The differing effects make general prediction of the state of an aquifer in glaciated terrains difficult.