The San Miguel lava flow is a porphyritic olivine basalt erupted from a small cinder cone on the eastern edge of the La Mesa surface in south-central New Mexico 10 miles south of Las Cruces. The elongate pattern of the flow and its present position indicate extrusion of the flow followed a pre-existing drainage channel into the Rio Grande Valley.

Texturally the flow is divisible into highly vesicular and scoriacious top and bottom zones with a more dense, columnar interior. The phenocryst mineralogy, consisting of approximately equal amounts of plagioclase and olivine with subordinate pyroxene, suggests correlation with one of the flows from nearby Black Mountain.

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