Restricted in areal usage to apply to partly graphitic and pyritic, pelitic, psammitic, calcarenitic rocks between Oakdale Formation and Proterozoic Z or Ordovician Nashoba Formation. May be equivalent in part to Tadmuck Brook Schist. Age is Silurian or Ordovician.
Source: GNU records (USGS DDS-6; Reston GNULEX).
Used as Boylston Schist of Ordovician or Silurian age. Consists of carbonaceous and locally sulfidic phyllite or schist, quartzite, and calc-silicate beds.
Source: GNU records (USGS DDS-6; Reston GNULEX).
For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.
Asterisk (*) indicates published by U.S. Geological Survey authors.
"No current usage" (†) implies that a name has been abandoned or has fallen into disuse. Former usage and, if known, replacement name given in parentheses ( ).
Slash (/) indicates name conflicts with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005, 2021). May be explained within brackets ([ ]).