San Juan basin of northwest New Mexico contains up to 15,000 feet of sedimentary rocks ranging from Cambrian to Recent. Thin, incomplete units of Cambrian, Devonian, and Mississippian are overlain by thick Pennsylvanian and Permian, unconformity, Triassic and Jurassic, unconformity, very thick Cretaceous, and thin lower Tertiary, and Quaternary terrace gravels resulting from mountain glaciation. Volcanism occurred during late Tertiary. The section contains much continental sediment and very small amounts of evaporites. Oil and gas are present in Pennsylvanian and Cretaceous beds; 94 million bbl of oil and 3 trillion cfg had been produced to Jan. 1, 1964. Cretaceous beds contain sub-bituminous coal with reserves of about 70 billion tons. Jurassic and Upper Cretaceous beds contain large uranium deposits, reserves estimated at 55 million tons.

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