A New Model for Coastal Resource Productivity and Sea‐Level Change: The Role of Physical Sedimentary Processes in Assessing the Archaeological Potential of Submerged Landscapes from the Northwest Australian Continental Shelf

Abstract

Existing models of coastal occupation, in one form or another, embrace the assumption that changes in mean sea level were the prime driver for shifts in coastal resource productivity of consequence to coastal foragers. Focusing on the North West Shelf of Australia, this paper considers the role of physical sedimentary processes in understanding both past coastal resource productivity and the archaeology of drowned coastal landscapes. From a review of up-to-date literature on sea-level related coastal formation process related to the North West Shelf, we describe the complex interplay of sea-level change and sedimentary processes in determining (i) coastal resource availability, and (ii) archaeological site preservation potential through time. We argue that human behavioral models that have been linked solely to changes in sea level change from ca. 45 ka onward along the Australia continental shelf have inadequately accounted for local sedimentary regimes. It is not past sea-level per se, which is of relevance to coastal productivity and human behavioral ecology models but changes in tidal regimes, coastal configurations and sedimentation. We conclude that our understanding of maritime adaptations for Sahul (Greater Australia) remain incomplete without investigating former coastlines and archaeological information that now lies submerged offshore. C 2014 Wiley Periodicals, Inc.

Physical sedimentary controls on subtropical coastal and shelf sedimentary systems: Initial application in conceptual models and computer visualizations to support archaeology

“…The full complexity of the interactions of sea‐level change with shelf and coastal sedimentary processes has not necessarily been fully grasped yet in the archeological literature, for example, compare Beaton () and O'Connell & Allen () to Ward et al. ().…”

“…In subtropical regions, cyclones and seasonal tropical storms can be critical controls on coastal geomorphology, for example, through reworking coastal sediments during storm surges. Such regions also house an ample range of sedimentary environments able to provide both resources for humans (Ward et al., ) and conditions likely to allow some preservation of coastal archaeology. As an example, cyclones are a key driver of sedimentary environments (Figure G) on the central Great Barrier Reef (GBR) shelf, especially the middle shelf but also parts of the inner shelf and coastline (Carter et al., ; Larcombe & Carter, ; Nott, ) where cyclones have been a routine occurrence for more than the last 6000 years.…”

“…There are profound archaeological implications. The sediment dynamics of shelf environments in northern Australia indicate frequent likely burial, exposure and/or reworking of archaeological remains, with reworking of material on the shelf being particularly intense and extensive, thus influencing preservation of non‐indurated seabed features, particularly during the latter stages of the post‐glacial transgression (Ward et al., ). It is unsurprising that, in Upstart Bay in North Queensland, Bird (, ) found that the majority of known archaeological sites were significantly reduced, modified or destroyed after tropical cyclones Charlie in 1988 and Aivu in 1989.…”

“…We explain the reasoning below (see also references in Table ). The literature indicates that the glacial lowstand tidal range at 20 ka (Siddall et al., ; Yokoyama, De Deckker, Lambeck, Johnston, & Fifield, ) was almost twice as great as today (Egbert, Ray, & Bills, ; Rudnick & Ferrari, ), so there are likely to have been large intertidal flats and a productive coastline with the capacity to have provided marine resources (James et al., ; Ward et al., ). The widespread presence of many drowned valley systems on the middle and outer shelf (e.g., Baker et al., ; Wilson, ; and a range of unpublished industry surveys) indicates the likelihood of past large estuarine systems, even though published core evidence to date is scarce.…”

“…Therefore, the information presently available provides some answers but not others. The contextual information derived from Boodie Cave on the western side of Barrow Island indicates that for much of the late Pleistocene and early Holocene (Ward et al., ; Veth et al., ), there was a diverse coastal environment with both marine and freshwater influences. As outlined above, a wave‐dominated system in the area, including a back‐barrier lagoon, might offer a range of brackish to marine resources, but extensive mangroves are unlikely, because of the likely dominance of sandy sediments, a steep foreshore and a relatively mobile intertidal zone.…”