A CHRONOLOGIC INVESTIGATION OF SAND DUNE FORMATION IN THE CAPITAL REGION OF NEW YORK STATE

The Albany-Schenectady sand plain lies west of the Hudson River and south of the Mohawk River in the Hudson-Mohawk Lowlands physiographic province of New York State. The sand plain occupies an area of approximately 125 km² and is composed of remobilized deltaic and lacustrine material originally deposited into glacial Lake Albany by the Iro-Mohawk River. As Lake Albany levels lowered, these deposits were exposed to the northwest wind, resulting in sand dune formation. This study provides data to develop a more concise timeline for initialization and stabilization of sand dunes using Optically Stimulated Luminescence (OSL), radiocarbon dating, and Ground Penetrating Radar (GPR).

OSL dating of sand samples collected from both the top (crest) and the bottom of the dune provides a timeline for dune formation. Organic material recovered from core samples taken in the low lying inter-dunal areas provides additional chronologic data to help constrain ages.

The uppermost OSL samples were collected at a depth of 1 m below the crestal plane of each dune. Preliminary results suggest that stabilization or re-stabilization of the dunes occurred in the mid-Holocene. GPR transects mapped subsurface stratigraphy and allowed for the approximate subsurface depth of the basal boundary of the dunes to be determined. These data, paired with dune elevation, allowed the lower sands to be collected by core sampler, to a maximum depth of 3-6 m below the base of the dune. The lowermost OSL dates are pending.

Adjacent to the dunes, in an effort to verify stratigraphy, continuous core samples were retrieved to depths of 18−20 m. Thus far, examinations of these cores have revealed two organic horizons. A 10 cm layer of aquatic moss was observed at a depth of 4.2 m, while a 20 cm layer containing spruce needles, charcoal and assorted detrital plant macrofossils was found at a depth of 9 m. Radiocarbon ages are pending.

Preliminary data suggest that the geomorphic history of the study area is more complex than previously thought. A more complete understanding of sand dune formation in this area has implications related to the chronology of glacial lakes in the Capital Region.