Eliot Formation

Phyllite and calcareous phyllite. In New Hampshire: Used as Eliot Formation of Merrimack Group. Consists of gray to green phyllite, calcareous quartzite, quartz-mica schist, and well-bedded calc-silicate. Includes Calef Member, mapped separately. Age of all formations in Merrimack Group changed to Ordovician(?) to Silurian(?) based on isotopic age determinations of approx 440 and 420 Ma from detrital zircons from Berwick Formation (of Merrimack Group) by J.N. Aleinikoff (oral commun., 1994) (Lyons and others, 1997).
State Massachusetts
Name Eliot Formation
Geologic age Silurian
Lithologic constituents
Major
Metamorphic > Metasedimentary > Metaclastic > PhyllitePhyllite and calcareous phyllite.
Comments Part of Merrimack Belt (Silurian, Devonian and Pennsylvanian Rocks). Secondary unit description per MA010.
References
NGMDB product
Counties Essex