Glacial Grooves. Cameron Hills, N.W.T. just to the south of the Canadian Shield. Continental ice sheets covered most of Canada, east of the Rocky Mountains, to a depth of hundreds of metres. When these massive lobes of ice advanced over the rocks they picked up, they gouged great grooves in softer bedrock. [NAPL/A18304-15]


CPR Tunnel near Schreiber, Ontario. The rugged Shield has often caused havoc for engineers building roads and railways in the North. [C.J. Humber]