The N30°–35°W trend of three long basaltic andesite dikes in west-central New Mexico indicates a least principal horizontal stress direction of N55°–60°E at the time the dikes were emplaced 28 m.y. ago. This stress direction agrees with recently proposed tectonic models for the region, suggesting that northeast-southwest extension was pervasive over both the early Basin and Range and Colorado Plateau provinces and the southern Rocky Mountains at this time.

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