Precambrian Grenville age, 1.1 byr, metamorphic rocks compose the Adirondack Mountains in upstate New York. Apatite fission track (FT) ages ranging from 168 ± 18 to 83 ± 11 Ma have been determined from ~50 samples analyzed in previous studies. Significant differences in apatite FT age exist between the western Adirondack-High Peak region and the southeastern Adirondacks.

An abrupt discontinuity was discovered between the summit of Dix Mt. (161 ± 22 Ma) and a nearby valley sample, on the Boquet River (90 ± 13 Ma). The magnitude of the discontinuity suggested differential unroofing between the sample locations. The age offset was investigated by collecting an additional 20 samples from the southeastern Adirondack region.

Six samples are being analyzed for apatite FT ages and track length distributions. A low elevation sample from a ledge on Sawteeth Mt., near the Ausable Lake lineament, was collected to assess potential FT age differences. Three additional samples from Minerva, Pharaoh Mt., and near Gore Mt. were collected for analysis because of their location in relation to mapped lineaments. A sample of Precambrian gneiss from Moss Is. in the Mohawk River, Little Falls, was collected to better delineate the FT ages along the southwestern Adirondack margin.

The results of these FT age determinations will add to the existing database for better interpretation of unroofing trends within the Adirondack region.