Abstract

The position of McGee stage till on top of McGee Mountain, California, has long been considered as evidence of 4000 feet of post-McGee vertical displacement along the Sierran frontal fault. Evidence and analysis (Lovejoy, 1964) have shown that such faulting preceded the emplacement of a basalt volcano and associated flows 2.6 m.y. ago, thus precluding significant post-McGee faulting. McGee glacial gradients of 900–1000 feet per mile, similar to measurements for younger glaciers in the region, indicate that McGee Canyon was shallower and steeper during McGee time. The McGee till therefore was most probably emplaced as an alb moraine. Its present position is not evidence of later Sierran frontal uplift by faulting.

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