Hitchcock Volcanics (MAJhv;0)

State	Massachusetts
Name	Hitchcock Volcanics
Geologic age	Lower Jurassic
Original map label	Jhv
Comments	Part of Mesozoic Basins (Jurassic and Triassic Rocks); Sedimentary and Volcanic Rocks of Hartford Basin. Secondary unit description per MA003 as reported in USGS Geologic Names lexicon (ref. MA024): The use of the name Hitchcock Volcanics follows that of Brophy and others (1967) and is assigned to the Newark Supergroup. It consists of nested cones of basaltic breccia containing abundant fragments of New Haven Arkose, locally intrusive into arkose near the base. It underlies the Shuttle Meadow Formation and (or) the Holyoke Basalt. Age is changed from Late Triassic to Early Jurassic (Robinson and Luttrell, 1985).
Primary rock type	volcanic breccia (agglomerate)
Secondary rock type	arkose
Other rock types
Lithologic constituents	Major Sedimentary > Clastic > Sandstone > Arkosecontaining abundant fragments of New Haven Arkose (Jn, TRn) Igneous > Volcanic > Mafic-volcanic > Basalt (Volcaniclastic, volcanic breccia)nested cones of basaltic breccia
Map references	Unpublished Digital Geologic Map of Massachusetts received from Rudi Hon at Boston College in 1998.
Unit references	Zen, E-An (ed.), Goldsmith, R. (comp.), Ratcliffe, N.M. (comp.), Robinson, P. (comp.), Stanley, R.S. (comp.), Hatch, N.L., Jr., Shride, A.F., Weed, E.G.A., Wones, D.R., 1983, Bedrock Geologic Map of Massachusetts: U.S. Geological Survey, Reston, VA, scale 1: 250,000. Robinson, Peter and Luttrell, G.W., 1985, Revision of some stratigraphic names in central Massachusetts, IN Stratigraphic notes, 1984: U.S. Geological Survey Bulletin, 1605-A, p. A71-A78. [http://pubs.er.usgs.gov/publication/b1605A] USGS Geologic Names Lexicon (GEOLEX) [http://ngmdb.usgs.gov/Geolex/]
Geographic coverage	Hampshire