TWO GENERATIONS OF PARABOLIC DUNES IN THE SARATOGA SAND PLAINS, HUDSON VALLEY, NEW YORK

Sand dunes in the northern Hudson Valley, New York, have long been recognized but little studied. Previous work included mapping of overlying eolian sand but focused on glaciolacustrine sediments associated with proglacial Lake Albany. New high-resolution (1 and 2 m) digital elevation data and associated hillshade models reveal that the sand dunes are more extensive than shown in this early mapping. We refer to this dune field as the Saratoga Sand Plains (SSP), which includes, but extends beyond, the SSP Wildlife Management Area.

Stabilized parabolic dunes of the SSP extend over an area ~120 km², along a ~33 km corridor up to ~8 km wide, between Queensbury and Saratoga Springs. Individual dunes formed limbs up to 3 km in length and >10 m high. Several other dune forms are identified, including compound, digitate, comb-shaped, and rarely simple dunes.

Dune orientations indicate two generations formed under different wind regimes. Low-relief dunes are found in a limited area (~10 km²) between Gansevoort and Ballard Corners and were formed from NNE winds. Dune limbs there range from <0.1-0.9 km in length. Partially preserved limbs rise to 5 m high but are more commonly <3 m. Dune heads appear Z-shaped towards the SW with open limbs to the NE. Within a few kilometers of Ballard Corners the dunes transition to a more dominant set formed by WNW winds. Preserved southerly limbs of parabolic dunes are more prominent resulting in an appearance resembling transverse dunes.

We interpret the difference in dune orientations and morphology to reflect changing climate conditions at the end of the Pleistocene. Soon after drainage of Glacial Lake Albany, the earliest dunes formed by katabatic or anticyclonic winds associated with the retreating Laurentide Ice Sheet. As the ice migrated farther north, it is likely that the influence of these winds decreased and subsequent prevailing northwesterly winds reworked earlier dunes. These younger dunes are similar in morphology and orientation to those found in the Albany Pine Bush Preserve <50 km to the south.