Cook Inlet province, which at present is the only productive oil region in Alaska, produced 66 million bbl of oil and 100 billion cu ft of gas in 1968. Commercial discoveries of major fields on the North Slope await solution of logistic problems before production can begin. Cook Inlet province occupies an intermontane sedimentary basin 900 mi (1,448 km) long and 5-50 mi (8-80 km) wide. It contains the oil-productive nonmarine Tertiary section, which overlies untested late Mesozoic rocks. Current estitmates of oil in place of 2.6 billion bbl may be increased to as much as 7.9 billion bbl. Gas in place, now estimated at 5 trillion cu ft, may total 14.6 trillion cu ft as a result of exploration of the Mesozoic secion and extension of the present restricted area of developmen . North Slope oil already is estimated to be more than 5 billion bbl on the basis of initial discoveries in only one of three potentially productive geologic zones. Other Tertiary sedimentary areas--e.g., Bristol Bay, the Bering Sea shelf, and the Pacific margin both onshore and offshore--hold less promise, but their potential is by no means negative.