Granby tufa is named for diabase tufa in the Triassic basin in MA.
Source: GNU records (USGS DDS-6; Reston GNULEX).
Granby tuff is bedded black tuff and tuffaceous sandstone varying from fine-grained volcanic sandstone to coarse diabase breccia derived from volcanic debris and granitic gneiss.
Source: GNU records (USGS DDS-6; Reston GNULEX).
A series of tuffs with interbedded tuffaceous sandstone and conglomerate, diabase, and intrusive pipes, dikes, and sills is referred to as the Granby tuff. It consists of four units: Granby tuff of Emerson (1898), a brown, purple, or maroon diabase tuff or tuffaceous sandstone; the Hampden diabase of Emerson (1898); numerous intrusive diabase pipes, dikes, and sills; and Black Rock diabase breccia dike of Emerson (1898).
Source: GNU records (USGS DDS-6; Reston GNULEX).
Used as Granby Basaltic Tuff of Early Jurassic age. [Name revision not explained.]
Source: GNU records (USGS DDS-6; Reston GNULEX).
Granby Tuff is renamed Granby Basaltic Tuff to reflect the composition of this friable, well-bedded tuff containing sediment fragments. Assigned to Newark Supergroup.
Source: GNU records (USGS DDS-6; Reston GNULEX).
For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.
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