Evolution of Holocene coastal environments near Robe, southeastern South Australia

Coastal Robe Range, and adjacent Woakwine Range, situated 10-15 km inland, are the most southwesterly and youngest of a series of parallel, low altitu de, Pleistocene beach-dune barriers in southeastern South Australia. In the early Holocene, the post-glacial marine transgression flooded the Robe-Woa kwine Corridor, thus forming a shallow back-barrier lagoon, open to the Sou thern Ocean near the present towns of Robe and Beachport. Marine to lagoona l, bioclastic, carbonate-quartz sedimentation prevailed within the corridor from ca. 7500-2000 yr BP. Along the seaward side of Robe Range, transgress ive sands were deposited initially as ephemeral sand flats, but were mostly redistributed as coastal dunes, which today remain active and blanket the Pleistocene core of the range. Sand was also transported along the coast an d deposited within the protected embayments of Guichen and Rivoli Bays, in the form of prograded beach ridge plains, eventually isolating the back-bar rier lagoon from the open ocean. Sediment aggradation within the lagoon, ce ssation of marine influence and regional uplift of 0.7 m during the Holocen e, combined to transform the corridor to a lacustrine landscape. Fossil mol luscs, foraminifera and ostracods are diagnostic of successive palaeoenviro nments, and thus signify stages in the rapid geomorphic evolution of the co astal Robe-Woakwine Corridor. (C) 1999 INQUA/Elsevier Science Ltd. All righ ts reserved.