Abstract -- Introduction -- Purpose and scope of the report -- Previous work -- The series name and its history -- Stratigraphic correlations of the series -- Previous correlations -- Walcott's correlation -- Calkins' correlations -- Daly's original correlation -- Schofield's correlation -- Drysdale's correlation -- Correlation by Wilson, Lambert, and Clapp -- Sampson's correlation -- Correlation by Clapp and Deiss -- Gibson's correlation -- Recent Canadian correlations -- Revised classification -- Basis of classification -- Definitions -- Pre-Ravalli rocks -- Ravalli group -- Piegan group -- Missoula group -- North Boulder group -- Purcell basalt and similar rocks -- Diagnostic features -- Lithologic criteria -- Color -- Texture -- Structure -- Paleontologic criteria / Richard Rezak -- Petrographic criteria -- Criteria in igneous rocks -- Criteria in carbonate rocks -- Criteria in clastic rocks -- Criteria related to degree of metamorphism -- Chemical criteria -- Major components -- Trace elements -- Lithologic descriptions -- Prichard formation -- Distribution -- Character -- Neihart quartzite -- Ravalli group -- Burke formation -- Distribution -- Character -- Revett quartzite -- St. Regis formation -- Altyn limestone -- Appekunny formation -- Distribution -- Character -- Grinnell formation -- Chamberlain shale -- Piegan group -- Wallace formation -- Distribution -- Character -- Newland limestone -- Distribution -- Character -- Siyeh limestone -- Distribution -- Character -- Missoula group -- Striped Peak formation -- Distribution -- Character -- Libby formation -- Beds of the Missoula group near Superior, Mont -- Rocks of the Missoula gorupo near Missoula, Mont -- Distribution -- Character -- Rocks of the Belt series in and near the Ovando and Silvertip quadrangles -- Distribution -- Character -- Rocks of the Missoula group in and south of Glacier National Park -- Distribution -- Character -- The Missoula group near and east of Helena -- Distribution -- Greyson shale -- Spokane shale -- Empire shale -- Helena limestone -- Marsh shale -- Greenhorn Mountain quartzite -- North Boulder group -- Distribution -- Character -- Genetic problems -- The terms "Archean" and "algonkian" in relation to the Belt problem -- The lower limit of the Belt series -- Form and extent of the basin -- Source of sediments -- Marine versus lacustrine deposition -- The upper limit of the Belt series -- North American relatives of the Belt series -- Idaho -- Utah -- Wyoming and Colorado -- Arizona and westward -- Texas and vicinity -- Canada and Alaska -- Summary -- Belt paleogeography -- References cited -- Index.

Plate 1. Geologic map of the Belt Series, Montana [on four sheets: NE quarter, NW quarter, SE quarter, SW quarter] -- Plate 2. Index map of northwestern Montana, showing the principal topographic features and the outlines of quadrangles and other areas in the region that are cited in this report -- Plate 3. Fence diagram showing stratigraphic relations of the principal units in the Belt series.