Bedrock hydrogeology

The map shows the location and distribution of bedrock aquifers. The quality is expressed by the total dissolved solids in parts per million and the quantity is expressed in litre per second. Bedrock deposits consist of sedimentary, metamorphic, and igneous rocks; Canada possesses all three types. Sedimentary rocks have a much greater aquifer potential than the other two types of bedrock, but because of their depth, they are less accessible and less economical to use than aquifers in the unconsolidated surficial materials. Metamorphic and igneous rocks, which have low porosity and permeability, are, in general, poor aquifers and expensive to exploit, although locally, fracturing and shear zones may provide reasonable groundwater supplies on a domestic or slightly larger scale. It must be realized that both quantity and quality of groundwater can vary markedly from one location to another over very short distances. Because of scale limitations, areas of salt-water intrusion along marine coastlines have not been delineated, nevertheless, this can be an important quality consideration in various areas in northeastern New Brunswick, Prince Edward Island, the lower St. Lawrence River, and the Gulf Islands of British Columbia.