Layered and massive gabbros of the Humboldt Lopolith and extrusive equivalents in west-central Nevada yield well-grouped paleomagnetic data on a site basis. With corrections for attitudes of compositional layering in gabbros and flow contacts in lavas (kcorrkin situ=5.5), the mean of 15 site means is: D=307¿, I=21¿, &agr;95=9¿, k=17. While K-Ar data imply a Late Jurassic age, we prefer an older, probably Early Jurassic, age for the lopolith and its magnetization based upon magnetization data and relations of these rocks with host strata. Compared with Early Jurassic expected directions, the data reveal a discordancy in declination of -37¿ (+/-14-22¿) which implies a significant counterclockwise rotation of the lopolith. Local rotation of Fence-maker allochthon units most likely occurred when southeasterly-directed thrust sheets obliquely contacted a generally north-south trending shelf margin. Mesozoic deformation will be more accurately estimated with better age control and measurement of possible Cenozoic crustal rotation.