Work on the Precambrian rocks of the Beartooth Mountains has been mainly in terrain dominated by gneiss. We undertook the current project in the belief that an intensive study of an area where the rocks perhaps were not as thoroughly reconstituted by metamorphic and igneous activity (as is the case farther east) and where metasedimentary rocks are exposed in substantial amounts might reveal a somewhat more detailed picture of Precambrian events than has emerged from earlier studies in the region. The North Snowy block constitutes such an area.

The northwestern part of the Beartooth Mountains is divisible into structural blocks...