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K'gari in South East Queensland, Australia, is the world's largest sand island and a UNESCO World Heritage Area. The island is covered by extensive coastal dune fields that have been divided into seven morphological units (the Awinya, Yankee Jack, Bowarrady, Triangle Cliff, Freshwater, Station Hill, and Cape). Optically-Stimulated Luminescence dating of the dune sequences indicate that the Awinya unit is > 340 ka, and the Yankee Jack and Bowarrady units are ca. 180 ka old. Holocene dune sequences comprise Triangle Cliff (ca. 8.5 ka); Freshwater (ca. 4 ka); Station Hill (ca. 1.5 ka) and Cape (ca. < 0.5 ka). Combining these data with dune ages from the adjacent Cooloola Sand Mass, we demonstrate that for at least the last three glacial cycles the dunes were emplaced during intermediate to high sea-levels. At shorter time intervals (decades to centuries), some dune formation is affected by storminess. Initial formation of the dune field occurred in the mid-Pleistocene, but the most recent widespread stabilisation of dunes occurred late in Marine Isotope Stage 7 (MIS 7: 190–240 ka). The preservation of dunes relates to antecedent topography coupled with the duration and height of individual interglacial high sea-stands. This research confirms K'gari as an outstanding example of geomorphological processes and supports its World Heritage listing. • First chronology of all the major parabolic dune units on K'gari (formerly Fraser Island), the world's largest sand island. • The dune units are emplaced during intermediate to high sea-levels at least as far back Marine Isotope Stage 7. • A major Late Holocene scarp suggests that major cyclones can penetrate SE Queensland on occasions. [ABSTRACT FROM AUTHOR]

Increased catchment erosion and nutrient loading are commonly recognized impacts of deforestation on global wetlands. In contrast, an increase in water availability in deforested catchments is well known in modern studies but is rarely considered when evaluating past human impacts. We used a Budyko water balance approach, a meta-analysis of global wetland response to deforestation, and paleoecological studies from Australasia to explore this issue. After complete deforestation, we demonstrated that water available to wetlands increases by up to 15% of annual precipitation. This can convert ephemeral swamps to permanent lakes or even create new wetlands. This effect is globally significant, with 9 to 12% of wetlands affected, including 20 to 40% of Ramsar wetlands, but is widely unrecognized because human impact studies rarely test for it. [ABSTRACT FROM AUTHOR]

Palynology of exhumed Pliocene marine turbidites and marl beds on the island of Timor provide insights into crustal deformation in the Indonesian region. Between ca. 4.5 and ca. 3 Ma, palynomorphs were sourced primarily from Australia and New Guinea, with increasing swamp and mangrove elements sourced from an emerging proto-Timor. Following ca. 3.1 Ma, pollen and charcoal evidence track the rapid uplift of Timor to a high island, with the progressive appearance of montane and dry, lee-side floristic elements. Early- to mid-Pliocene uplift rates of 0.5-0.6 mm yr-1 increased to 2-5 mm yr-1 in the latest Pliocene. The rapid topographic development of Timor-Leste initiated earlier but followed a pattern similar to that of more westerly localities in the Timor sector of the Banda Arc. Timor's emergence from the marine environment is closely correlated with the timing of closure of the Indonesian seaway to deep-dwelling foraminfera. [ABSTRACT FROM AUTHOR]

The Cooloola Sand Mass is a large coastal dune field situated in southeast Queensland, Australia and is part of a much larger system of coastal dune fields, including the world's largest sand Island, Fraser Island, as well as Moreton Island and Stradbroke Island. Cooloola is characterised by a sequence of onlapping, parabolic dune units that have been emplaced episodically over the Pleistocene and Holocene. The tectonically stable coastline of SE Queensland is an ideal area to study the driving mechanisms of coastal dune development, as sea level variability is driven primarily by glacial eustasy. Geomorphic and chronostratigraphic analyses have identified seven major periods of dune activity with the earliest phase of deposition occurring ca. 800 ka. Subsequent periods of dune emplacement date to about ca. 150 ka, 110 ka, 10–6 ka, 5–3.5 ka, ca. 2 ka and 0.4–0.2 ka. The Holocene dune activity coincides with the last stages of post-glacial marine transgression and suggests these large parabolic dunes formed in response to rising sea levels. It is likely that this pattern is consistent through the Pleistocene, and the MIS 5 interglacial period is also recorded. For earlier events the large absolute errors on the ages make interpretation difficult. There is a notable absence of OSL ages dating to the Last Glacial Maximum and no ages that are unambiguously associated with lowstand periods. This is most likely because the coast would have been 60 km offshore of its current position during lowstands, limiting sediment supply and wind energy at the modern coast. These results provide strong evidence that coastal dune fields in SE Australia are predominantly emplaced during sea-level rise, as originally proposed in the Cooper-Thom model. [ABSTRACT FROM AUTHOR]

Subtropical to tropical sandy beaches are subject to a wide variety of processes that influence shoreline position, though they receive little research attention compared to temperate coastlines. This presents challenges to understanding the drivers of long-term coastal change, particularly in places like the sub/tropical margins of Australia, where there are significant differences in local to regional geologic, oceanographic, and climatic conditions. Here, we investigate changes in beach planform morphology for a number of beaches in Queensland, Australia, over a period of up to 90 years using high resolution (0.5–5 m pixel size) aerial photographs. In total, 945 images were orthorectified and bounding features for the subaerial beach (high water and dune vegetation lines) were digitised to extract shoreline change statistics for 15 beaches ranging from the tropics to subtropics, between 15°S and 28°S. Three beach types were identified, defined based on lateral boundary features and the scale of shoreline/beach width variability. These include low variability beaches with two bounding rocky headlands (type 1); beaches with one headland and one river boundary, with the most significant shoreline adjustment away from the headland (type 2); and highly variable beaches with two river boundaries (type 3). Our change analysis demonstrates overall seaward displacement of the high water and vegetation lines, but also net losses in beach width due to fast rates of seaward vegetation advance in a tropical setting. These changes are largely consistent along this coastline, despite differences in exposure to deep-water waves and large variation in tidal ranges. Long-term accretion persists here despite rising sea levels over the past century. This result suggests a long-term net positive sediment budget along this section of the coast that is likely a reflection of global adjustments to tropical climate, and associated increases in terrestrial sediment generation and dune vegetation growth rates. Overall, this study provides insights into a variety of coastal settings through the subtropics and tropics and highlights the importance of tracking change along both the landward and seaward edges of the subaerial beach, regardless of exposure and associated wave regimes. • Tropical beach width declines while shorelines advance seaward. • Dune vegetation cover has increased, reducing the size of subaerial beaches. • Variability in beach width is drastically higher on beaches bound by rivers. • Alongshore supply of fluvial sediment dominates in low wave energy tropical areas. • Data-driven analyses provide more detailed insights into decadal coastal change. [ABSTRACT FROM AUTHOR]

Little is known about the Pleistocene climatic context of northern Australia at the time of early human settlement. Here we generate a palaeoprecipitation proxy using stable carbon isotope analysis of modern and archaeological pandanus nutshell from Madjedbebe, Australia's oldest known archaeological site. We document fluctuations in precipitation over the last 65,000 years and identify periods of lower precipitation during the penultimate and last glacial stages, Marine Isotope Stages 4 and 2. However, the lowest effective annual precipitation is recorded at the present time. Periods of lower precipitation, including the earliest phase of occupation, correspond with peaks in exotic stone raw materials and artefact discard at the site. This pattern is interpreted as suggesting increased group mobility and intensified use of the region during drier periods.

Increased catchment erosion and nutrient loading are commonly recognized impacts of deforestation on global wetlands. In contrast, an increase in water availability in deforested catchments is well known in modern studies but is rarely considered when evaluating past human impacts. We used a Budyko water balance approach, a meta-analysis of global wetland response to deforestation, and paleoecological studies from Australasia to explore this issue. After complete deforestation, we demonstrated that water available to wetlands increases by up to 15% of annual precipitation. This can convert ephemeral swamps to permanent lakes or even create new wetlands. This effect is globally significant, with 9 to 12% of wetlands affected, including 20 to 40% of Ramsar wetlands, but is widely unrecognized because human impact studies rarely test for it., (Copyright © 2014, American Association for the Advancement of Science.)