In the New York City area, the allochthonous Hartland Formation and its Pelham Bay Member and related Ravenswood Granodiorite, east of Cameron's Line, overlie Manhattan Schist Member C of Early and Middle Cambrian age. The age of the Hartland, Pelham Bay, and Ravenswood ranges from Middle Cambrian to Middle Ordovician (fig. 2).

Source: GNU records (USGS DDS-6; Reston GNULEX).

In NY City, Cameron's Line, a tectonic boundary which shows evidence of extreme compression and thrust faulting, separates the Manhattan Prong with its Middle Proterozoic Fordham Gneiss overlain by C and O allochthonous units on the west, from the allochthonous eugeoclinal Hartland Formation and Ravenswood Granodiorite on the east. The Hartland is mapped in the east Bronx and Queens; the Ravenswood in is Queens, Kings, and lower east Manhattan. All 3 of these were previously mapped as Brooklyn Gneiss or Brooklyn Injection Gneiss which should be abandoned. The age of the Hartland and Ravenswood is Cambrian and Ordovician, based on correlation with rocks of southwestern CT, their relative positions and lithologic similarities. Isotope data on the Ravenswood gives an early Paleozoic age, probably Early Ordovician.

Source: GNU records (USGS DDS-6; Reston GNULEX).