Late Quaternary stratigraphy and sea-level history of the northern Delaware Bay margin, southern New Jersey, USA: a ground penetrating radar analysis of composite Quaternary coastal terraces

Ground penetrating radar (GPR) and lithologic data reveal six Pleistocene sea-level highstand sequences, forming two composite terraces along the northern margin of Delaware Bay in southern New Jersey, USA. The upper terrace (+ 18 to + 9 m MSL) is underlain by four estuarine-marine sequences of middle Pleistocene age, while the lower terrace ( + 6 m-MSL) contains 2 middle to late Pleistocene sequences. Separating the 2 terraces is a variably sloping escarpment (Cedarville) created by erosion during at least 2 high sea-level events. Intensive radar imaging and boring of these 6 unconformity-bounded units allows for their interpretation in a sequence-strati graphic context, identifying transgressive, highstand, and regressive phases. Higher than present sea levels of + 14, + 12, + 6, and + 16 in during the middle Pleistocene, and + 5 m during the middle and/or late Pleistocene are indicated by these sedimentary sequences, suggesting relative stability of this section of the Atlantic Coastal Plain during the past 500 ka. GPR analysis of coastal drainage modification reveals a contrasting lowstand sequence of incised paleovalleys, supporting the interpretation that these bay-margin deposits contain one of the most complete sections of late Quaternary highstand stratigraphy in the Mid-Atlantic region. For appendix see http://www.elsevier.nl/locate/quascirev. (C) 2002 Elsevier Science Ltd. All rights reserved.