Stephen A. Norton, 1976. "Hoosac Formation (Early Cambrian or Older) on the East Limb of the Berkshire Massif, Western Massachusetts", Contributions to the Stratigraphy of New England, Lincoln R. Page
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The Hoosac Formation has been divided into 10 units. These are, from oldest to youngest, (1) quartz-pebble and polymictic-pebble meta conglomerate with a schist matrix, 0 to 160 m thick; (2) quartz-plagioclase-muscovite-biotite-(garnet) schist, 0 to 35 m thick; (3) quartz-muscovite-garnet schist with abundant quartz lenses, 0 to 65 m thick; (4) quartz-plagioclase-muscovite-biotite-(garnet) schist, 0 to 35 m thick; (5) quartz-muscovite-garnet schist, commonly with discontinuous layers composed nearly entirely of Fe-Mg-Al silicate minerals, 0 to 65 m thick; (6) quartz-plagioclase-muscovite-biotite schist, 350 to 3,500 m thick; (7) slightly calcareous quartz-muscovite schist, interbedded with schist of unit 6 in a zone ranging from 0 to 65 m thick; (8) schist of unit 6, 350 to 3,500 m thick; (9) quartz-plagioclase-garnet-muscovite schist, 0 to 65 m thick; and (10) schist of unit 6 with minor impure quartzite, locally graphitic. The Hoosac Formation is about 6 km thick at the Vermont border, thins to less than 1 km near Becket, Massachusetts, and thickens to about 3 km at the Connecticut border. West of the Precambrian terrane, units 1, 3, and 4 locally underlie, grade into, and are interbedded with the Dalton Formation of Early Cambrian age.