Paleomagnetic samples obtained from Rawls Formation (26.9-28.3 Ma) lava flows of Bofecillos volcano in west Texas give a paleomagnetic pole at lat 76.5°N, long 348.0°E (α95 = 9.4°; N = 20). This pole is displaced significantly from North American reference poles of similar age, implying a clockwise rotation of 21.3° ± 8.8°. It is also consistent with other paleomagnetic data from west Texas. We argue that the discordance is a result of vertical-axis crustal rotation in west Texas caused by shear deformation that was probably related to Basin and Range tectonics.

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