Hortonville Formation - shale and phyllite

Dark-gray siliceous shale and phyllite containing thin beds of bluish-gray argillaceous limestone and minor beds of gray to tan quartzite. Grades into limy shales of the Stony Point Formation. Unit mapped west of the Taconic allochthon, and northwest of the Sudbury slice. Vermont Valley sequence and Middlebury synclinorium (above the Orwell and Champlain thrusts).
State Vermont
Name Hortonville Formation - shale and phyllite
Geologic age Upper Ordovician
Lithologic constituents
Major
Metamorphic > Metasedimentary > Metaclastic > PhylliteDark-gray siliceous shale and phyllite.
Sedimentary > Carbonate > Limestone (Bed)Thin beds of bluish-gray argillaceous limestone.
Sedimentary > Clastic > Mudstone > Shale (Bed)Dark-gray siliceous shale and phyllite.
Minor
Metamorphic > Metasedimentary > Metaclastic > QuartziteMinor beds of gray to tan quartzite.
References
NGMDB product
Counties Addison - Rutland