Two wells recently completed in the Plainview basin of the Panhandle of Texas have yielded important geologic information concerning the age of the basement complex. A core from the Humble Oil and Refining Company's Howard Ranch No. 1, Briscoe County, Texas, contained unmetamorphosed fossiliferous Paleozoic sediments intruded by diabase. This fact indicates that a part of the "Swisher gabbroic terrane" is younger than Precambrian. Another core, from the Humble Oil and Refining Company's Reinauer No. 1, Deaf Smith County, Texas, was determined by the K-Ar method to have a minimum age of 650,000,000 years, or late Precambrian. A reexamination of all the wells drilled in the "Swisher gabbroic terrane" indicated that much of the gabbro is a diabase.

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