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Cram Hill Formation - undivided
Predominantly dark-gray to grayish-green quartz-chlorite-(biotite)-muscovite phyllite; contains 1- to 2-cm-thick beds of dark-gray metasiltstone and quartzite, and thicker beds of dark-bluish-gray vitreous quartzite, grayish-green to light-yellowish-green sericite phyllite (felsic tuffs) and cobble to boulder conglomerate, and greenstone. Mapped north of the Braintree Intrusive Complex and near Brattleboro. Part of the metasedimentary host rocks of the North River Igneous Suite. Cram Hill Formation: western part of the Cram Hill Formation is in part correlative with Whetstone Hill Member of the Moretown Formation. Rocks of the Early to Late Taconic Accreted Terrane of the Rowe-Hawley Zone. Eastern allochthonous sequence, oceanic and accretionary realm, ultramafic inclusions, volcanic-arc intrusives, and volcanic rocks.
State |
Vermont |
Name |
Cram Hill Formation - undivided |
Geologic age |
Middle? and Early Ordovician |
Lithologic constituents |
Major
Metamorphic > Metasedimentary > Metaclastic > PhyllitePredominantly dark-gray to grayish-green quartz-chlorite-(biotite)-muscovite phyllite; contains 1- to 2-cm-thick beds of dark-gray metasiltstone and quartzite. Grayish-green to light-yellowish-green sericite phyllite (felsic tuffs).
Minor
Sedimentary > Clastic > ConglomerateCobble to boulder conglomerate.
Metamorphic > Metasedimentary > Metaclastic > QuartziteDark-bluish-gray vitreous quartzite.
Metamorphic > Metaigneous > Greenstone
Incidental
Metamorphic > Metasedimentary > Metaclastic > MetasiltstonePredominantly dark-gray to grayish-green quartz-chlorite-(biotite)-muscovite phyllite; contains 1- to 2-cm-thick beds of dark-gray metasiltstone and quartzite.
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References |
Ratcliffe, N.M., Stanley, R.S., Gale., M.H., Thompson, P.J., and Walsh, G.J., 2011, Bedrock geologic map of Vermont: U.S. Geological Survey Scientific Investigations Map 3184, 3 sheets, scale 1:100,000.
https://pubs.er.usgs.gov/publication/sim3184 |
NGMDB product |
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Counties |
Orange - Orleans - Washington - Windham
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