Remains identified as those of a woolly mammoth ( Mammuthus primigenius ) dated at 12,200 ?? 55 14C yr B.P. were recovered while excavating in a complex sequence of glaciomarine sediments in Scarborough, Maine, USA. The mammoth was found in the top meter of a fossiliferous unit of mud and sand laminites. These sediments were deposited during a marine regressive phase following the transgression that accompanied northward retreat of the margin of the Laurentide ice sheet. A Portlandia arctica valve from the underlying transgressive unit provides a minimum age of 14,820 ?? 105 14C yr B.P. for local deglaciation. The mammoth, an adult female, died in midwinter with no evidence of human involvement. Tusk growth rates and oxygen-isotope variation over the last few years of life record low seasonality. The mammoth was transported to the site as a partial carcass by the late-glacial proto-Saco River. It sank in a near-shore setting, was subjected to additional disarticulation and scattering of elements, and was finally buried in sediments reworked by the shallowing sea. ?? 2004 University of Washington. All rights reserved.