Turner Valley is Alberta's first great oilfield. Initially the field, which began production in 1914, yielded mainly natural gas. Local plants, which provided the only extensive gas-processing system in the province, extracted the marketable petroleum products. The discovery of deeper reserves in 1924 at Royalite No. 4 made Turner Valley the leading producer in Canada. In 1936, the crude-oil pool underlying the gas reserves was discovered and Turner Valley reached peak output. While production declined after 1942, the field continues to be a significant producer of oil and gas.