New optical age of the Mescalero sand sheet, southeastern New Mexico

Abstract

The Mescalero sand sheet that covers most of the Mescalero Plain is formed by two eolian sand bodies, the Lower and Upper units. New and revised OSL ages indicate that the Lower unit accumulated 90–50 ka and the Upper unit was deposited 18–5 ka. Both eolian units are dominated by massive, well-sorted, fine quartz sand. The Lower sand directly overlies the eroded surface of the calcic Mescalero paleosol. The top of the Lower sand incorporates the Berino paleosol, a red argillic soil that formed on the sand sheet during the comparatively wet and cool environment of the late Wisconsinan. The Lower sand and the Berino paleosol are buried by the Upper eolian sand. An unnamed Bw paleosol at the top of the Upper sand formed during the past 5 ka. Locally, archaeological sites younger than 3,000 b.c. are on the surface, whereas older sites are buried within the Upper sand. During the twentieth century, the shrub grassland vegetation of the Mescalero sand sheet was disturbed, leading to the formation of many coppice and parabolic dunes.