THE PEVERLY BROOK LINEAMENT AND SCARP IN SOUTHEASTERN NEW HAMPSHIRE: A LATE PLEISTOCENE- OR HOLOCENE-AGE FAULT?

Recently available LiDAR data revealed a conspicuous, ~30-km-long, NNE-SSW-trending lineament in southeastern New Hampshire which we have named the Peverly Brook lineament. The lineament is defined on LiDAR imagery by the collinear alignment of the Winnicut River valley and other low-lying areas south of Great Bay, the Peverly Brook drainage and east-facing, en échelon scarps between Great Bay and Little Bay, and the 10-km-long NNE-trending segment of the Piscataqua River northeast of Newington, NH. The east-facing scarps are 3-5 m high and are formed in Pleistocene glaciomarine sediments, which suggests that the scarps have undergone displacement during late Pleistocene or Holocene time. Two seismic reflection profiles were recently collected across one of the scarps in Newington and are currently being processed. An electrical resistivity profile acquired across this scarp revealed a decrease in resistivity near the scarp, suggesting that there may be a brecciated fault zone at depth. The orientation of the Peverly Brook lineament relative to the ENE-WSW-oriented axis of maximum compressive stress field in central New England favors oblique dextral displacement along the lineament. If the scarps along the Peverly Brook lineament are fault-related and offset the glaciomarine sediments, it would represent the first discovery of a late Cenozoic fault scarp in central New England.