Northern Canada consists of two political subdivisions. Yukon Territory and the Northwest Territories. Some 3.8 million km2 of land and the large continental shelf lie north of lat 60°N, which is the southern boundary of the two territories. The land area comprises 40 per cent of the whole of Canada. Distances are great, topography varies from flat plains and muskeg to high mountains, and variations in temperature are extreme. Nevertheless, despite these difficulties, the north is a land of great change and rapid development, particularly in the field of mineral exploitation. It was once considered that these territories were destined to remain a producer of precious metals only—commodities of high unit value. The turning point in mining developments came in November 1964, when the first shipment of ore from the Pine Point lead-zinc deposits marked the start of the tremendous and continuing surge forward in mining development. The oil and gas industry has also shown a keen interest in the potential of northern Canada in recent years and the sedimentary basins are all but covered with oil and gas exploration permits. A significant gas strike has been made in the Arctic archipelago and, far away in the south-west corner of the Northwest Territories, a major gas pool is being developed in the Pointed Mountain area.