Justine Kemp

Late Quaternary evolution of Riverine Plain paleochannels, southeastern Australia

The Riverine Plain of southeastern Australia is the result of prolonged Cenozoic fluvial activity associated with the Murray River and its major southern tributaries, the Murrumbidgee, Goulburn and Lachlan. Single thread, distributary and anabranching channels and floodplains with associated eolian dunes and lunette-bordered lake basins characterise the uppermost sequences of the Late Quaternary. Following 30 years of detailed mapping and stratigraphic investigation, more recently supported by luminescence dating, the Pels sequential model of prior streams and ancestral rivers on the Riverine Plain was replaced with the Page & Nanson model of alternating migrational and aggradational paleochannels. Despite some sub-catchment variability the emerging picture of climatic and hydrological change since the Last Interglacial shows many common themes that are in accord with findings in other parts of Australia including the Lake Eyre Basin and the coastal rivers of New South Wales. Enhanced fluvial activity is apparent in much of Oxygen Isotope Stage (OIS) 5 between 110 and 80 ka and in OIS 3 from 55 to 25 ka. The intervening OIS 4 represents a definite pause between pluvial episodes with an almost complete absence of luminescence dates from both riverine and lacustrine environments supported by evidence of enhanced dune mobilisation and high Antarctic dust flux. OIS 2 from 24 to 12 ka remains somewhat enigmatic with evidence for intense aridity in the Willandra Lakes and elsewhere at the Last Glacial Maximum apparently contradicted by evidence of higher flows in the Darling and Lachlan Rivers and high water levels at Lakes Tandou, Urana and Cullivel. The question of the persistence of the Lachlan Rivers connection with the Willandra Lakes at this time remains an unresolved issue in urgent need of further study. Despite uncertainty about the nature of the Last Glacial Maximum, it is now clear that higher stream discharges and lake levels occurred later in OIS 2 from about 20 to 12 ka. Dating evidence shows that the transition to essentially modern river regimes occurred early in the Holocene, but may have been somewhat asynchronous between the various Murray Basin sub-catchments.

Student-Produced Podcasts as an Assessment Tool: An Example from Geomorphology

The emergence of user-friendly technologies has made podcasting an accessible learning tool in undergraduate teaching. In a geomorphology course, student-produced podcasts were used as part of the assessment in 2008–2010. Student groups constructed radio shows aimed at a general audience to interpret and communicate geomorphological data within the context of relevant social and environmental issues. Questionnaire results suggest that the novel format engaged students, and promoted group working, IT, language and oral communication skills, and a deeper understanding of the context of geomorphic data. For teachers, podcasting technology offers efficient teaching of oral communication, with opportunities for distance and self-directed learning.

Progress in Australian dendroclimatology: Identifying growth limiting factors in four climate zones.

Dendroclimatology can be used to better understand past climate in regions such as Australia where instrumental and historical climate records are sparse and rarely extend beyond 100years. Here we review 36 Australian dendroclimatic studies which cover the four major climate zones of Australia; temperate, arid, subtropical and tropical. We show that all of these zones contain tree and shrub species which have the potential to provide high quality records of past climate. Despite this potential only four dendroclimatic reconstructions have been published for Australia, one from each of the climate zones: A 3592year temperature record for the SE-temperate zone, a 350year rainfall record for the Western arid zone, a 140year rainfall record for the northern tropics and a 146year rainfall record for SE-subtropics. We report on the spatial distribution of tree-ring studies, the environmental variables identified as limiting tree growth in each study, and identify the key challenges in using tree-ring records for climate reconstruction in Australia. We show that many Australian species have yet to be tested for dendroclimatological potential, and that the application of newer techniques including isotopic analysis, carbon dating, wood density measurements, and anatomical analysis, combined with traditional ring-width measurements should enable more species in each of the climate zones to be used, and long-term climate records to be developed across the entire continent.

Digging your own grave: OSL signatures in experimental graves.

Excavation of mock graves in sediments of aeolian and fluvial origin were conducted to test the bleaching efficiency of grave digging in materials that commonly host ancient burials in Australia. Grave-size pits were dug into Pleistocene aeolian sediments at Willandra Lakes and younger fluvial sediments on the Lachlan River, backfilled, and re-excavated. Samples for optical dating were taken from sediment infilling the mock graves and from the adjacent, undisturbed substrate, and analysed using the single aliquot-regenerative dose (SAR) protocol applied to single quartz grains. The resulting equivalent dose (De) distributions revealed that ≤1% of grains had been fully zeroed in both settings, and an additional 1-6% of poorly bleached grains were apparent in the fluvial sediments. Insufficient and heterogeneous bleaching of sediments during excavation and backfilling produced a decrease in the central dose of between 3 and 6 Gy, and an increase in over-dispersion values of between 5 and 10%. These differences were insufficient to clearly distinguish the disturbance event from the effects of bioturbation, biological mixing, or other sources of De variation. The use of the Minimum Age Model substantially over-estimated the burial age (zero years) in both depositional environments, with the degree of over-estimation increasing with the age of the host sediments. These results suggest that optically stimulated luminescence (OSL) techniques will not produce accurate ages for grave infill in a number of forensic and archaeological settings. Further study of the bleaching susceptibility of grains within grave infills, as well as the effectiveness of grave-digging as a bleaching mechanism is required. In other archaeological and geomorphological applications of OSL dating we recommend routine checks on the effective zeroing of sediments in modern equivalent situations.

Diversifying assessment across the ‘Two Cultures’: student-produced podcasts in Geography

Abstract Since 2008, following growing collective interest in learning technologies and pedagogy, Geography and History departments at Northumbria and Newcastle Universities have successfully incorporated student-generated podcasting into a mixture of science, humanities and social science modules across all undergraduate levels. This paper presents a number of innovative examples using this approach, with the aim of promoting student creativity and analytical skills in ways different from traditional report- or essay-based assessments. It goes on to consider some of the advantages and challenges of this alternative assessment mode, from both student and tutor perspectives, across the science-humanities divide.

The effect of riparian restoration on channel complexity and soil nutrients

Restoration of riparian vegetation may reduce nutrient and sediment contamination of waterways while potentially enhancing stream channel complexity. Accordingly, the present study used a paired-site approach to investigate the effects of mature regrowth riparian vegetation on river channel morphology and soil nutrients (i.e. nitrogen and phosphorus), comparing four sites of degraded (pasture) and reforested reaches. A revised rapid assessment of riparian condition (RARC) was used to validate the site pairings. Riparian soil nutrient and elemental geochemistry were compared between paired sites, along with two parameters of channel width complexity and two for channel slope complexity. The RARC analysis confirmed the validity of the paired site design. The elemental geochemistry results indicated that underlying geology may affect the paired site analyses. Reaches with mature regrowth vegetation had greater channel width complexity but no difference in their riverbed slope complexity. In addition, degraded reaches had higher soil nutrient (i.e. nitrogen and phosphorus) concentrations, potentially indicative of the greater nutrient retention of pasture grass sites compared with mature regrowth forested reaches with less ground cover. Overall, the present study indicates that restoring mature regrowth riparian vegetation may increase river channel width complexity, although it may require canopy management to optimise the nutrient retention potential necessary to maximise the effect of riparian restoration strategies on freshwater environments.

The death of Kaakutja: a case of peri-mortem weapon trauma in an Aboriginal man from north-western New South Wales, Australia

Abstract Skeletal remains from a burial in New South Wales exhibit evidence of fatal trauma, of a kind normally indicative of sharp metal weapons, yet the burial dates to the mid thirteenth century—600 years before European settlers reached the area. Could sharp-edged wooden weapons from traditional Aboriginal culture inflict injuries similar to those resulting from later, metal blades? Analysis indicates that the wooden weapons known as ‘Lil-lils’ and the fighting boomerangs (‘Wonna’) both have blades that could fit within the dimensions of the major trauma and are capable of having caused the fatal wounds.