MICROFOSSILS IN THE DRUMLIN TILL OF BOSTON HARBOR, MASSACHUSETTS

At least two tills of different ages are found in New England and in the drumlins of Boston Harbor, Massachusetts. The surface till is of late Wisconsinan age. The lower drumlin till is probably early Wisconsinan in age based on amino acid age estimates of fossil Mercenaria shells and the depth of weathering in the till. This probably reflects incorporation of last interglacial marine sediment (Stage 5) into the drumlin till during early Wisconsinan time.

We examined samples of unoxidized and unleached till from Long Island in Boston Harbor. There are numerous microfossils in the till. Preliminary identification shows 13 species of benthic foraminifera and two ostracode species. These microfossils probably indicate preglacial and interglacial warmer-than-present, shallow-water marine or estuarine paleoenvironments.