LATE PLEISTOCENE ICE-MARGINAL DUNE FIELDS ON THE ATLANTIC COASTAL PLAIN, NEW JERSEY PINE BARRENS, USA

During glacial episodes, source-bordering parabolic dunes evolved on the flat sandy terrain of the Pinelands National Reserve under cold, dry, windy conditions. Today the area is densely forested, obscuring the extent of dunes within a humid temperate region 50–150 km south of the maximum Laurentide Ice Sheet margin. Terrestrial relicts including frost cracks, deflation basins, and ventifacts attest to periglacial conditions in the area. However, the allostratigraphical organization of windblown sand into dunes has received scant attention in the Pine Barrens, despite recent recognition and mapping of coeval inland dunes along the Eastern US Coast from Delaware to Georgia.

Elongate parabolic (aka hairpin-type) dunes are comprised of re-transported Late Miocene fluvial and marginal marine deposits. We examined dune distribution to better understand the significance of ice-marginal wind-action and dune-sand morphology within three small (<1500 km²) river watersheds: 1) the Mullica; 2) the Great Egg Harbor; and 3) the Maurice. Remote sensing was conducted at Stockton University using high resolution (1 meter) down-looking LiDAR to reveal the bare-earth ground surface. Two sample sites were examined from each of the three watersheds to assess the dune field dynamics. Five study locations were dune crests and one was a lunette that rims a deflation basin. Soil observation pits were excavated (~150 cm deep), profiles stratigraphically documented, and sand samples collected for optical dating. Eighteen sand samples were examined for grain analysis by scanning electron microscope (morphoscopy) and for improved Cailleux Method of surface-texture interpretation at the University of Warsaw. Dune orientation (~NW–SE) and morphology suggest that the eolian deposits were influenced by strong katabatic winds emanating from the glacial ice sheet. Grain-surface morphoscopy is further shown to be a useful tool in discerning dune-sand transport activity and the post-depositional environment.