John Pickard

Exposure ages from mountain dipsticks in Mac. Robertson Land, East Antarctica, indicate little change in ice-sheet thickness since the Last Glacial Maximum

Past changes in East Antarctic Ice Sheet (EAIS) volume are poorly known and diffi cult to measure, yet are critical for predicting the response of the ice sheet to modern climate change. In particular, it is important to identify the sources of sea-level rise since the Last Glacial Maximum (LGM), and ascertain the present-day stability of the world’s largest ice sheet. We present altitudinal transects of 10 Be and 26 Al exposure ages across the Framnes Mountains in Mac. Robertson Land that allow the magnitude and timing of EAIS retreat to be quantifi ed. Our data show that the coastal EAIS thinned by at most 350 m in this region during the past 13 k.y. This reduction in ice-sheet volume occurred over a ~5 k.y. period, and the present icesheet profi le was attained ca. 7 ka, in contrast to the West Antarctic Ice Sheet, which continues to retreat today. Combined with regional offshore and terrestrial geologic evidence, our data suggest that the reduction in EAIS volume since the LGM was smaller than that indicated by contemporary ice-sheet models and added little meltwater to the global oceans. Stability of the ice margin since the middle Holocene provides support for the hypothesis that EAIS volume changes are controlled by growth and decay of Northern Hemisphere ice sheets and associated global sea-level changes.

Early Pliocene marine sediments, coastline, and climate of East Antarctica

We record the first onshore late Tertiary fossiliferous marine deposit from the 8000-km-long coastline of East Antarctica. Glaciomarine sediments containing abundant diatoms and molluscs were deposited in shallow waters off an open coast during the early Pliocene (∼4.5-3.5 Ma) and are now exposed less than 15 m above sea level on Marine Plain in the Vestfold Hills (lat 68°359S,long 78°009E). Marine diatoms suggest early Pliocene as the most probable age of the sediments. Fossil sand wedges show that the deposit was above sea level at least briefly before it was covered with water and subsequently capped with glaciomarine till. The coastline at the time of deposition of the marine sediments is inferred to have been close to but farther inland than that of today. The ice margin may have been ∼50 km farther inland, considerably reducing the ice volume of Antarctica. Climate at the time of deposition was interglacial and perhaps warmer than the present.

The evolution of Watts Lake, Vestfold Hills, East Antarctica, from marine inlet to freshwater lake

Abstract Watts Lake is a 0.38 km2 freshwater lake in the Vestfold Hills, East Antarctica (68°35′S 78°00′E) that was formerly a marine embayment. The water level of the lake is currently rising, it is now at −5.8 m altitude. The lake currently has a maximum salinity of 2.4 g 1−1 and no outlet. Abundant Holocene marine fossil molluscs, polychaetes and algae dated at 4700–8000 14C yr B.P. indicate that the lake was one basin of a complex marine inlet during the early to mid Holocene. A prominent terrace formed in the tide zone during this period. Processes involved in terrace formation are discussed using Watts Lake as an example. Other basins of this inlet have now become saline or hypersaline. Isostatic uplift isolated the whole inlet from the sea and allowed the basins to become separate lakes. From 3000–4000 14C yr B.P. copious volumes of freshwater from nearby stagnant ice and possibly from a major river system poured into Watts Lake displacing the salt water over a sill at the eastern end. Within 2000 yr the lake was fresh. Freshwater inflow declined and the lake level began to fall from evaporation. Cyanobacterial stromatolites formed from 2800 to 1700 14C yr B.P. at the eastern end of the lake. At least two other lakes in the Hills have similar histories.

The Transition from Shepherding to Fencing in Colonial Australia

The transition from shepherding to fencing in colonial Australia was a technological revolution replacing labour with capital. Fencing could not be widespread in Australia until an historical conjunction of technological, social and economic changes: open camping of sheep (from about 1810), effective poisoning of dingoes with strychnine (from the mid-1840s), introduction of iron wire (1840s), better land tenure (from 1847), progressive reduction of Aboriginal populations, huge demand for meat (from 1851) and high wages (from 1851). Labour shortages in the gold-rushes of the early 1850s were the final trigger, but all the other changes were essential precursors. Available data are used to test the alleged benefits of fencing: a higher wool cut per head; an increased carrying capacity; savings in wages and the running costs of stations; less disease in flocks; larger sheep; higher lambing percentages, and use of land unsuitable for shepherding. Many of the benefits were real, but some cannot be verified. By the mid-1880s, over ninety-five per cent of sheep in New South Wales were in paddocks, wire fences were spreading rapidly, and the cost of fences was falling. However, shepherding persisted in remote northern areas of Australia until well into the twentieth century.

Wire fences in colonial Australia : technology transfer and adaptation, 1842-1900

After reviewing the development of wire fencing in Great Britain and the United States of America in the early nineteenth century, I examine the introduction of wire into Australia using published sources only. Wire was available in the colonies from the early 1850s. The earliest published record of a wire fence was on Phillip Island near Melbourne (Victoria) in 1842. Almost a decade passed before wire was used elsewhere in Victoria and the other eastern colonies. Pastoralists either sought information on wire fences locally or from agents in Britain. Local agents of British companies advertised in colonial newspapers from the early 1850s, with one exceptional record in 1839. Once wire was adopted, pastoralists rejected iron posts used in Britain, preferring cheaper wood posts cut from the property. The most significant innovation was to increase post spacings with significant cost savings. Government and the iron industry played no part in these innovations, which were achieved through trial-and-error by pastoralists. The large tonnages of wire imported into Australia and the increasing demand did not stimulate local production of wire, and there were no local wire mills until 1911. It is now, I presume, quite understood that wire-fencing is the best and cheapest fencing that can be adopted in almost any circumstances (Munro, 1850: 426) It is not at all probable, that however durably wire-fences may be erected, they will ever supersede thorn hedges or stone dykes on farms. (Stephens, 1855: II, 596) Introduction Technology is one of the underpinnings of society, no matter how primitive or advanced. The economic development of colonial societies depended heavily on technology imported from the country of origin and subsequently adapted for local conditions. The history of technology in Australia has been a neglected field of historical study (Blainey, 1964), but the past two decades have seen at least two major Australian studies of technological (Todd, 1995) and technical (Raby, 1996) change and transfer. The difference is primarily one of semantics, and although less correct, ‘technology’ seems to be the more common usage for essentially the same thing: accumulation of information (in both objects and

Shepherding in Colonial Australia

Shepherds were a critical component of the early wool industry in colonial Australia and persisted even after fencing was adopted and rapidly spread in the later nineteenth century. Initially shepherds were convicts, but after transportation ceased in the late 1840s, emancipists and free men were employed. Their duty was the same as in England: look after the flock during the day, and pen them nightly in folds made of hurdles. Analysis of wages and flock sizes indicates that pastoralists achieved good productivity gains with larger flocks but inflation of wages reduced the gains to modest levels. The gold rushes and labour shortages of the 1850s played a minor role in increasing both wages and flock sizes. Living conditions in huts were primitive, and the diet monotonous. Shepherds were exposed to a range of diseases, especially in Queensland. Flock-masters employed non-whites, usually at lower wages, and women and children. Fences only replaced shepherds when pastoralists realised that the new technology of fences, combined with other changes, would give them higher profits. The sheep were left to fend for themselves in the open paddocks, a system used to this day.

Griffith Taylor's ‘palimpsest theory’ of the dry valleys of Victoria land, antarctica

Abstract Griffith Taylor was the first geomorphologist to work in the Dry Valleys of southern Victoria Land, Antarctica. Following his field work in February 1911, he proposed a multistage model in which earlier cirque erosion was later swamped by expanding outlet glaciers. Subsequently these glaciers retreated leaving the present form of the valleys. The topography retained the imprint of each episode, hence his name ‘palimpsest theory’. I summarise later research and compare Taylors theory with current views.

Safe carrying capacity and sustainable grazing: how much have we learnt in semi-arid Australia in the last 170 years?

The paper reviews Australian literature on estimating carrying capacity on rangelands from 1823 to 1998. Graziers assume that current stocking rates (numbers of domestic stock per unit area) are identical with the sustainable carrying capacity. It is argued that in virtually all cases, current stocking rates in semi-arid Australia exceed the carrying capacity of the landscape. Despite this, these stocking rates are considered acceptable by both graziers and government agencies. Empirical research by graziers shows that lowering stocking rates by up to 60% increases incomes and improves the vegetation. These lowered stocking rates are probably close to safe carrying capacities and hence sustainable grazing.