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A thick, allochthonous sequence of quartzite and schist exposed on Mount Harrison in the Albion Mountains, Idaho, is proposed to stratigraphically correlate with the upper part of the Proterozoic Z McCoy Creek Group and the Proterozoic Z and Lower Cambrian Prospect Mountain Quartzite in the Pilot Range, Utah and Nevada. The presence of these miogeoclinal strata in the Albion Mountains suggests that anomalous stratigraphic units elsewhere in the range are not of Cambrian age.

The correlation of units in the Albion Mountains and the Pilot Range is based on lithology, thickness, and sedimentary structures. Ambiguous low-angle fault relations in the Albion Mountains and moderate metamorphism of the section in that range preclude a positive correlation with units in the Pilot Range. Correlation of strata in the Albion Mountains with middle Proterozoic or early Paleozoic strata exposed in central Idaho is shown to be less probable.

The strata on Mount Harrison identified as Proterozoic Z and Lower Cambrian in this study are part of an overturned, structurally complex sequence of metasedimentary rocks that lie tectonically on overturned, metamorphosed Cambrian(?) shale and/or Mississippian shale and metamorphosed Ordovician carbonate strata; if the intervening rocks are Cambrian rather than Mississippian, these relations suggest that a largely miogeoclinal sequence (Proterozoic Z to Ordovician) similar to sequences in nearby mountains may once have been present near the Albion Mountains area. Elsewhere in the Albion Mountains and the adjoining Raft River and Grouse Creek Mountains, however, metamorphosed Ordovician carbonate rocks appear to stratigraphically overlie metamorphosed clastic rocks of uncertain age that differ from miogeoclinal rocks of the region. The section on Mount Harrison may be a relict of a more complete section that is tectonically thinned elsewhere in the metamorphic terrane, or it may be a far-traveled allochthonous slice of miogeocline juxtaposed with nonmiogeoclinal-facies strata of similar age.

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