Abstract The current strong motivation to explore those traces of the archaeological and prehistoric human heritage that presently lie submerged on the continental shelf requires large-scale and precise underwater mapping. One Mediterranean sector deserving particular attention is the Sicily Channel, which is critical for a better understanding of the Africa–Europe migratory routes and early civilization patterns due to its large expanses of shallow seabed that were partially or totally exposed at times of lower relative sea levels. We have focused our attention on the submerged continental margin of the Maltese archipelago. A detailed bathymetric map is here presented, and is discussed in terms of features interpretable as former subaerial landforms and inundated by sea-level rise following the Last Glacial Maximum lowstand at approximately –130 m. Our datasets combine multibeam surveys, Light Detection And Ranging (LiDAR)-derived digital terrain models (DTMs), Chirp sub-bottom profiler records and bottom samples acquired between 2009 and 2012. The main features identified are former river incisions, alluvial plains, karst landscapes (sinkholes, limestone plateaus), slide deposits and palaeoshorelines. This study provides a detailed topographical reconstruction of the palaeolandscape of this key region that is relevant to any future archaeological exploration of the Maltese offshore area.

Abstract Recent underwater archaeological surveys recovered hundreds of flint artefacts between depths of 18 and 21 m at Cala Tramontana, a small bay located in the eastern part of Pantelleria Island. Most of the flint artefacts indicate debitage, and are characterized by cores and flakes without any specific morphology. Different lithic tools were also identified, such as fragments of blades, truncations, end-scrapers, points and crested blades. An initial hypothesis is that this lithic industry represents the oldest traces of human visitation to the island, possibly related to the exploitation of the nearby obsidian source, and favoured because of the sheltered coastal configuration of Cala Tramontana and Cala Levante with respect to the dominant winds and related storms. However, the present-day coastal setting in the bay is rather inhospitable, with high cliffs and difficult marine access. In contrast, palaeo-landscape reconstructions by means of high-resolution multibeam bathymetry reveal the possible presence of a small palaeo-beach in the inner part of the bay when the sea level was 15 m lower than at present. By comparing this palaeo-sea level with the eustatic curve (and by excluding possible vertical movements), we roughly estimate an age of the lithic industry of 9.6–7.7 cal ka BP.

Abstract This paper focuses on the continental shelf of NW Australia, and on models for change in littoral and offshore environments of relevance to human occupation over the last 50 kyr. Major island groups occur on the shelf including the Montebello and Barrow islands, and those of the Dampier Archipelago. At lowest sea level around 22 ka, these would have been uplands that then became progressively isolated by subsequent sea-level rise. By integrating archaeological and zooarchaeological records from excavations on these islands with the geology and geomorphology, we interpret palaeoeconomic resource potential in relation to changing sea level and coastline morphology. The preservation potential for submerged archaeological sites and features is also assessed. Current archaeological evidence from these offshore islands indicates that the submerged coastal landscape is likely to have been a potentially rich environment for resources and human occupation, even at times of lowest sea level and regional aridity. Should any exploration of submerged archaeology be carried out in this region, it is likely to be rewarding, offering unique insights into Late Pleistocene coastal occupation.

Abstract Sealed, submerged palaeoenvironmental deposits date the time range for lithic technologies and enable inferences about cultural change – potentially more accurately than radiometric methods. Sea-level rises triggered by global warming reduce available land, and change the availability of flora, fauna, geological resources, rivers and wetlands. Australian archaeological studies on human adaptation to climate change focus mainly on terrestrial sites, coastal intensification and the few archaeological sites that were not inundated. The South West Arm project at Port Hacking, south of Sydney, looks at the potential for rock shelters to survive inundation and expand the sites available for studying human adaption to climate change. Site prediction was based on recorded terrestrial rock-shelter landforms at South West Arm. Underwater surveys were conducted by divers who located, photographed and mapped similar formations. No excavation was conducted. The pre-disturbance survey examined approximately 1800 m of seabed, between water depths of 0 and 9 m, primarily along the eastern shoreline of South West Arm where the seabed emulates the steep slope, with sandstone rock outcrops that form terraces and rock overhangs above water. Twelve submerged rock overhangs were recorded and confirmed the potential for rock-shelter sites to survive the process of inundation.

Abstract In this paper we review the main, long- and short-term geological and geotectonic processes that have controlled the development of Pleistocene landscapes in the Aegean region above and below the fluctuating sea level. We discuss the potential for further research on reconstruction of submerged landscapes of the continental shelf and beyond with the aim of addressing questions concerning Palaeolithic settlement. The geological, tectonic, morphological and hydrogeological background provides information for the assessment of the natural resources available to hominins. Along with the palaeogeographical evolution of the shallow coastal and shelf areas, they are examined in parallel with the terrestrial archaeological record in order to open windows to future work in a region that has remained marginal to human origins research. On the basis of the multi-variable tectonic evolution and geomorphological configuration of the coastal and shelf areas, we propose to divide the Aegean region into nine geographical units, each with its own geotectonic and morphological history and traits. These units can be further grouped to provide larger neighbouring and culturally meaningful regions, suitable for archaeological analysis, or subdivided to provide smaller target areas in which to work.

Abstract Coastal geomorphic systems have been studied widely to understand the responses of shorelines to fluctuating sea levels. Submerged shorelines, remnant of Pleistocene sea-level lowstands, are well preserved on the South African continental shelf. This paper describes work undertaken to better understand offshore coastal environments now submerged by high sea levels off the South African south coast near Mossel Bay, offshore of the Pinnacle Point archaeological locality. Multibeam bathymetry and side-scan sonar reveal evidence of past sea-level fluctuations and submerged coastal landscape features on the seabed. These results form the basis of an ongoing palaeoenvironmental reconstruction for this part of the shelf. We describe seven significant geomorphic features that show a submerged environment that differs significantly to the immediate adjacent coastal plain. However, these features are comparable to other stretches of the present South African shoreline that serve as modern analogues. We propose that features on the continental shelf primarily reflect geological substrate, gradients and Pleistocene sea-level fluctuations. Early modern humans were likely to have had a different set of resources to use in this Pleistocene landscape compared to those available along the presently exposed coast.

Abstract Protected tidal inlets in four estuaries along 100 km of the south-central Oregon coast contain tidal-marsh stratigraphic sequences that suggest different styles of relative sea-level rise during the late Holocene. The south-central coast lies 70 to 90 km east of the leading edge of the overriding North America plate in the central part of the Cascadia subduction zone. Localized differences in the style of submergence along this actively deforming coast imply differences in the rate and extent of coastal subsidence or uplift during subduction of the Juan de Fuca plate beneath the North America plate. Thick tidal-marsh peat in the northern part of the study area records gradual submergence (1.0-1.6 mm/yr since 2.0-2.5 ka) that rules out large (>0.5 m), sudden changes in relative sea level, such as have occurred along other subduction-zone coasts during some historic great earthquakes (magnitude>8). In the south part of the study area, changes in intertidal lithofacies across abrupt transgressive and regressive overlap boundaries are consistent with localized coseismic subsidence and uplift of about 0.5 to 1.0 m above faults and folds in the accretionary wedge of the North America plate. Most coseismic deformation on these local structures probably coincides with great subduction earthquakes, but some localized deformation may reflect much smaller earthquakes that occur independently of plate-boundary events.

Abstract Holocene sediment thicknesses measured from seismic-reflection profiles, together with long-term rates of sediment accumulation calculated from these thicknesses and the history of relative sea level, indicate that the Chesapeake Bay has filled rapidly with sediment during Holocene submergence of the bay. Sediment-accumulation patterns indicate that both the Susquehanna River system and the continental shelf are important sources of sediment; averaged over Holocene time, sediment transported from the continental shelf through the mouth of the bay may be volumetrically more important than sediment derived from rivers. Average Holocene rates of sediment accumulation show considerable spatial variability, presumably related to local variations in sediment sources, wave energy, and tidal currents. Nonetheless, these rates show several clear trends. Rates on the shallow marginal shelves of the bay tend to be low (0 to 2 mm/yr) and to increase only slightly toward the bay mouth. Rates in the deep channels are higher (1 to 5 mm/yr), have local maxima, and increase distinctly toward the bay mouth. At any given position in the bay, sediment-accumulation rates increase with depth to the base of the Holocene section. Our estimates of average Holocene rates of sediment accumulation are clearly higher in many places than previous estimates, but they are somewhat less than short-term rates previously measured by a variety of methods. Short-term rates may be affected by anthropogenic changes in the basin and by recent acceleration of relative sea-level rise. In addition, most short-term rates are site specific, biased in their distribution, and fail to account for the large spatial variability observed in long-term rates. Maximum long-term rates of sediment accumulation are limited by the rate of submergence; many existing short-term measurements clearly cannot be extrapolated back in time. Long-term rates of sediment accumulation confirm the ephemeral nature of estuaries and the close tie between sea level and estuarine history. These observations are important considerations for studies of the evolution of estuaries and the record of estuaries in the geologic record.