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Mount Toby Formation (MAJmc;0)

Geologic Formation in MA

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Lithology

Sandstone

Conglomerate

Geologic Age

Sinemurian – Pliensbachian (199.6 Ma – 183.4 Ma ago)

Geologic Unit Label

Jmc

Pale red conglomerate and arkosic sandstone, coarsens eastward. The Mount Toby Conglomerate is here revised and renamed the Mount Toby Formation of the Newark Supergroup. It includes only the sedimentary strata in the Deerfield basin above the slump zone unconformity defined by Cornet (1977), or its projected equivalent at its contact with the underlying Turners Falls Sandstone. It includes conglomerates at the type locality, landslide deposits within the conglomerate, and sandstone and lake beds above the slump zone unconformity, which were formerly included in the Turners Falls Sandstone. Other rocks mapped as Mount Toby Conglomerate by Emerson (1898) in the Hartford, Deerfield, and Northfield basins have been assigned to the Portland, Sugarloaf, and Turners Falls Formations. Age is Sinemurian and Pliensbachian, based on the discovery by Cornet (1977) of palynoflora in these strata (Robinson and Luttrell, 1985).

— USGS

Taxonomy

Classified As

Geologic Formation