The Ensenada and Buenos Aires formations (Pleistocene) in a quarry near LaPlata, Argentina

An interdisciplinary study of a section in a quarry near La Plata sheds new light on the geologic, climatic, and biologic evolution of the northeaster n Pampean area of Argentina. The stratigraphic succession is composed of se ven mainly eolian levels, each one including a soil and separated by a disc onformity. Two geosols defined in northern Buenos Aires Province (Hisisa an d El Tala) are identified in the Ensenada Formation. The boundary between t he Ensenada and Buenos Aires formations is defined by a conspicuous disconf ormity which overlies the El Tala Geosol. Ln the section, the boundary betw een the Tolypeutes pampaeus (Ensenadan) and Megatherium americanum (lower L ujanian) biozones coincides with that of Ensenada and Buenos Aires formatio ns. The boundary between the Matuyama and Brunhes zones of polarity occurs in the upper part of the Ensenada Formation above the Hisisa Geosol. Accord ing to geologic evidence, most of the succession was deposited under semiar id to arid climate. (C) 1999 Elsevier Science Ltd. All rights reserved.