Single-step, laser-fusion 40 Ar/ 39 Ar ages of single muscovite grains with an automated micro-extraction system is a precise and relatively rapid way of analyzing large numbers of grains. This study used >500 muscovite grains from a late Wisconsinan sandy loess from eastern Long Island, New York, in order to evaluate the potential of Ar-Ar ages of single grain muscovite as a provenance tool for loess. The samples for dating were from a 2.7 m core of sediments from a small kettle hole in Wildwood State Park on the north shore of Long Island. These eolian deposits consist of a bimodal distribution of poorly sorted medium silt and medium sand that are buff colored, homogeneous, and unstratified. Long Island is a good place to test this approach, because the 40 Ar/ 39 Ar and K/Ar ages for muscovite in the potential bedrock sources to the north in New England vary systematically from ca. 450 Ma in the west to ca. 200 Ma in the east. The majority of muscovite ages in the loess range from 250 to 400 Ma, and muscovite age populations along the core show a change in proportion of muscovite input from the different provenances in New England. The results of this study confirm that using 40 Ar/ 39 Ar ages of a large number of single muscovite grains is a good method for examining the provenance of muscovite in loess, and thus understanding processes that produce loess.

Westhampton Beach is located between two stabilized inlets (Shinnecock and Moriches Inlets) on a barrier island on the south shore of Long Island, New York. Increasing beach erosion in the 1970s prompted a request for construction of a groin field to trap sand and restore the beach. The U.S. Army Corps of Engineers developed a plan for the groin field, and their recommendation was to sequentially build the groins up drift (eastward toward Shinnecock Inlet) using standard project design. However, in the late 1970s, local community pressure forced the U.S. Army Corps of Engineers, contrary to project design, to construct the groins down drift (westward) toward Moriches Inlet. The aim was to restore the eastern, more commercial, part of Westhampton Beach first. Financial limitations in 1972 suspended the project before its completion. Unfortunately, this set the stage for serious problems because the groin field was meant to operate as a completed project, and major problems developed soon after project termination. As a result, severe erosion and multiple washovers occurred west of the last groin. The major nor'easter of 1992 breached the island and destroyed many homes. The U.S. Army Corps of Engineers, in an emergency operation, dredged offshore sand and filled the breaches before they widened too much for effective closure. The subsequent litigation among the homeowners, the county, and the state spread over a number of years. A final settlement was reached on 31 October 1994. However, in a time of sea-level rise on a developed barrier island between two stabilized inlets, more people and bigger structures have now been put in peril.

Tills that discontinuously underlie the late Wisconsinan till throughout New England represent the penultimate full glaciation of the region. In southern New England, the late Wisconsinan till and the tills that locally underlie it are informally referred to as upper and lower tills, respectively. For the most part, the ages of the lower tills are not firmly established, and regional correlations between occurrences of lower till, including those on Long Island, New York, are tenuous. Where a lower till underlies deposits having limiting middle Wisconsinan radiocarbon ages (e.g., the Montauk till member of the Manhassett Formation on Long Island at Port Washington, New York, and the lower till at New Sharon, Maine), many workers have assigned the till an early Wisconsinan age. However, lower tills throughout much of New England may be Illinoian or older in age and may correlate with a lower till exposed at Sankaty Head, Nantucket Island, Massachusetts, that is pre-Sangamonian in age. The till at Sankaty Head lies below marine beds containing marine faunas indicative of sea-water temperatures both warmer and slightly cooler than those off Nantucket today and that have uranium-thorium and amino-acid racemization (AAR) age estimates suggesting a Sangamonian age (marine oxygen-isotope stage 5). The lower till at Sankaty Head and the Montauk till member on Long Island were deposited during a full glaciation of New England that was at least as extensive as the late Wisconsinan advance of the Laurentide ice. Global ice-volume data from the marine oxygen-isotope record and the late Pleistocene eustatic sea-level record inferred from raised coral terraces support an advance of this magnitude during marine oxygenisotope stage 6, but not during stage 4. An early Wisconsinan age of the southern New England lower tills and, hence, of the penultimate glaciation there is problematic in terms of the pre-Sangamonian age of the lower till on Nantucket, and in terms of the late Pleistocene global ice-volume and sea-level records. An Illinoian age for the tills and for the penultimate full glaciation of New England is compatible with all the available evidence except some equivocal radiocarbon ages and AAR age estimates.