Abstract

The Rossendale Gully site lies in a small underfit valley on the southeastern Assiniboine Delta. Previous radiocarbon dates on buried organics from this site were important in establishing the deglacial chronology of southern Manitoba (Preston et al., 1955; Elson, 1967; Teller, 1989). A new coring program was initiated in order to: (1) reconstruct early Holocene vegetation dynamics following the final regression of glacial Lake Agassiz across the delta; (2) correlate the Rossendale sequence with other Campbell-level deposits; and (3) model the broad relationship between late Paleoindian land-use and the history of Lake Agassiz in this region. In July 2003, 14 cores were collected from the region using a hydraulic Geoprobe. The longest core obtained was 13.25 m. A preliminary stratigraphic sequence is identified, composed of >12 m of offshore silt interbedded with at least eleven cycles of turbidite deposition, locally overlain by an early Holocene organic unit at the Rossendale Gully site. In general, this sequence documents the final regression of Agassiz from an earlier highstand phase (radiocarbon dates pending), followed by the first colonization of the delta surface by wetland vegetation  9.5 ka BP. This suggests that the southeastern delta was not available for human settlement until the late Paleoindian period.