YinZhou Huang Field investigations including lake shoreline measurement and 14C chronology have been carried out on the Alxa Plateau to better understand the formation and evolution of the high lake levels in northwest China during the late Pleistocene. Comprehensive field investigations show that there are at least ten shorelines at different elevations at Juyan Lake, at least four on the northwest side of the Jilantai Salt Lake, and nine shorelines and one terrace on the northeast margin of Zhuye Lake. Stratigraphic correlations and chronological evidence indicate that the paleo-lakes have the highest lake levels in Marine Isotope Stage MIS 3. Though the optically stimulated luminescence OSL results which have been reported by some scholars do not support this view, the fact that the paleo-lakes have the highest lake levels in MIS 3 can not be denied. Differences between OSL and 14C results from this work might indicate that high lake levels existed on the Alxa Plateau during two different periods. This paper also provides the basic hydrological information for further water resources research in this arid region. Tweet This is a preview of a remote PDF:
Aeolian sands were found to overlie the alluvial, diluvial, and lacustrine sediments in this desert. The OSL ages reveal that the latest sand accumulation began around 19 ka in the northwestern part and 9 ka in the eastern part of the Hobq Desert. Around 7 ka, the sand accumulation was strengthened and extended southward and northward 2 ka to develop the present desert landscape.
Our study suggests that the aeolian sand accumulation around 19, 9 and 7 ka resulted from the weakening of the Asian summer monsoon over this region. However, the rapid development of the present Hobq desert landscape since 2 ka was likely triggered by human activities in this desert.
() Since the s, thermoluminescence (TL), optically stimulated luminescence (OSL) and infrared stimulated luminescence (IRSL) dating are available providing the possibility for dating the time of loess (dust) deposition, i.e. These are called “paha ridges” in America and “greda ridges” in Europe.
Godthelp in Hill, Robert S. White, , The Nature of Hidden Worlds: Australian Conservation Foundation, Melbourne. Michael Archer, Suzanne J. Gehling, Kathleen Grey, Guy M. Franklin, The revolution that didn’t arrive:
Publications Academic Profile Abi’s research interests lie within understanding the dynamics of dryland systems, including environmental change, landscape dynamics and groundwater resources. She is interested in these processes and dynamics over a range of timescale and applies techniques to address questions about whether groundwater aquifers are part of the active hydrological cycle and questions about the timing and forcing mechanisms of expanding and contracting Quaternary drylands.
Abi is currently working with Prof. Mike Edmunds and Prof.
South China is an important region for the investigation of the origin of modern humans and the dispersal of Homo sapiens in Asia. However, the accurate dating of Paleolithic sites, especially for open-air sites, in the region has been difficult due to the lack of datable materials like bones that were destroyed due to intense chemical weathering.
Advanced Search Abstract All exposed rocks on Earth’s surface experience erosion; the fastest rates are documented in rapidly uplifted monsoonal mountain ranges, and the slowest occur in extreme cold or warm deserts—millennial submeter-scale erosion may be approached only in the latter. The oldest previously reported exposure ages are from boulders and clasts of resistant lithologies lying at the surface, and the slowest reported erosion rates are derived from bedrock outcrops or boulders that erode more slowly than their surroundings; thus, these oldest reported ages and slowest erosion rates relate to outstanding features in the landscape, while the surrounding landscape may erode faster and be younger.
We present erosion rate and exposure age data from the Paran Plains, a typical environment in the Near East where vast abandoned alluvial surfaces — km2 are covered by well-developed desert pavements. These surfaces may experience erosion rates that are slower than those documented elsewhere on our planet and can retain their original geometry for more than 2 m.
Major factors that reduce erosion converge in these regions: The 10Be concentrations in amalgamated desert pavement chert clasts collected from abandoned alluvial surfaces in the southern Negev, Israel representing the Sahara-Arabia Deserts , indicate simple exposure ages of 1. The 36Cl in carbonate clasts, from the same pavement, weathers faster than the chert and yields simple exposure ages of — ka or maximum erosion rates of 0.
These ages and rates are exceptional because they represent an extensive landform. The 10Be concentrations from samples collected at depth and optically stimulated luminescence OSL dating reveal a two-stage colluvial deposition history followed by eolian addition of 40 cm of silt during the past k. Our results highlight the efficiency of desert pavement armor in protecting rocks from erosion and preserving such geomorphic surfaces for millions of years.
Geology 10Be terrestrial cosmogenic nuclide dating of alluvial surfaces in the Coachella Valley, southern California, shows two alluvial fan surfaces with ages of When combined with additional fan dates from the Mojave and Sonoran Desert climatic regimes, statistically relevant episodes of fan production in southern California and Baja California were identified by mean standard weighted deviance analysis.
Three major episodes have been identified at These correlate well with the first 2 ka of glacial advance with the Sierra Nevada as established by dating of moraines and rock flour analysis of lake cores from Owens Lake.
Aeolian samples from deserts in northern China were studied using the optically stimulated luminescence (OSL) of quartz and potassium (K) feldspar separates. K-feldspar has shown advantages over quartz for dating samples younger than years, due to its more homogeneous equivalent dose (De) values, higher internal dose rate and higher luminescence sensitivity to dose.
The geomorphology of desert dunes. Routledge, London and New York. Interpreting and modelling late Quaternary dune accumulation in the southern Arabian Peninsula. Quaternary Science Reviews, Allostratigraphy and Quaternary dune sediments: Not all bounding surfaces are the same. Reproducibility and utility of dune luminescence chronologies. Modelling the formation of residual dune ridges behind barchan dunes in North-east Brazil.
Spatial and temporal patterns of aeolian activities in the desert belt of northern China revealed by dune chronologies. Optical dating of dune sands in the northeastern deserts of China. Palaeogeography Palaeoclimatology Palaeoecology,
Dr Abi Stone
Significant changes in environmental dose rate in part of the section could be shown to have occurred from measurements of the present day radioactivity and by the age reversal for some samples that had been dated by optically stimulated luminescence OSL measurements on quartz. These changes in dose rate can be attributed to recent uptake of radioactive elements found in the sediments; this resulted in significant underestimation of the OSL ages. In this study, the new isochron method using K-feldspar grains has been applied to overcome the effects of changes in dose rate.
Calculations are used to show that changes in the environmental dose rate factors, i. K, U, Th, water content and cosmic ray flux, and disequilibrium in the U and Th decay chains, e. After applying the new isochron method, the effects of changes in dose rate caused by recent uptake of radioactive elements and changes in past water content were effectively overcome and true ages are obtained; this was verified by repeating the luminescence isochron measurements on samples of overlying and underlying sediments.
Aeolian samples from deserts in northern China were studied using the optically stimulated luminescence (OSL) of quartz and potassium (K) feldspar separates. K .
Engelmann Verlag Heidelberg, pp. Charles Lyell brought this term into widespread usage by observing similarities between loess and loess derivatives along the loess bluffs in the Rhine and Mississippi. At that time it was thought that the yellowish brown silt-rich sediment was of fluvial origin being deposited by the large rivers. Verh Geol Reichsanst, Berlin, pp 1— These water conservation works were carried out extensively in China and the research of Loess in China has been continued since Liu TS, Loess and the environment Much effort was put into the setting up of regional and local loess stratigraphy and their correlation Kukla , , Geologiske Foreningen Foerhandlingar After the Australopithecus, pp.
Loess near Hunyuan , Shanxi province, China. Loess is homogeneous , porous , friable , pale yellow or buff , slightly coherent , typically non- stratified and often calcareous. Loess grains are angular with little polishing or rounding and composed of crystals of quartz , feldspar , mica and other minerals. Loess can be described as a rich, dust-like soil. It generally occurs as a blanket deposit that covers areas of hundreds of square kilometers and tens of meters thick.
Loess often stands in either steep or vertical faces.
The sedimentary sequence and landscape of the Hobq desert was observed through twelve profiles along five N-S sections extending through the entire desert. Aeolian sands were found to overlie the alluvial, diluvial, and lacustrine sediments in this desert. Optically stimulated luminescence (OSL.
Yellabidde Cave, Northern Swan Coastal Plain, Southwestern Australia Aboriginal History of Australia Aboriginal people have lived in Australia for at least 60, years, arriving by boat from south Asia at about that time, or possibly earlier. By 35, BP to 25, BP ancestral Aboriginal People had occupied all major environmental zones of Sahul Greater Australia , from the large islands off the northeastern coast of Papua New Guinea in the equatorial region, to the southernmost part of Tasmania.
At the time of the arrival of Europeans in Australia it was declared an unoccupied land, as the Aboriginal People didn’t practice agriculture, so the colonists could take over without even consulting the locals. The Aboriginal People were believed by some of those Europeans to be at best, like children, who needed to be protected from themselves as well as everyone else. Others regarded them as sub-human, so there was no problem treating them as though they were animals, especially when colonisation got under way and colonists wanted to take over their hunting territory for raising cattle and sheep, or farming.
They were mostly tolerated as long as they didn’t try to stop pastoralists taking their land, when they got in the way, they were often treated like animals that ate the colonists’ crops or killed their cattle for food.
Lion head in ivory, Kostenki 1. Despite being tiny, this sculpture is realistic and vivacious. Marl soft, chalky limestone , height 15 mm. Kunstkamera, St Petersburg Lion head. Ralph Frenken Source and text: A collection of stone tools from Kostenki 1.
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Publications Academic Profile David Thomas is a geomorphologist and physical geographer specialising in contemporary drylands and the Quaternary Period. Much of his research has been carried out in Africa, but he also conducts research in Arabia, Asia, India, North America and other dryland contexts. His research has often been multi- and interdisciplinary. On the one hand he has led interdisciplinary projects on desertification, land degradation, sustainable land use and climate change impacts; on the other he works on projects focussed on geomorphological processes, Late Quaternary environmental change, climate change science and environmental-climate interactions, with archaeologists, biologists, climate scientists and other physical geographers.
Gilbert and Kenneth Mason. Prior to returning to Oxford, where he was a student from for undergraduate, Cert. Phil degrees, David was at Sheffield University, rising from lecturer to Professor in the Department of Geography between and , founding the Sheffield Centre for International Drylands research in Director until and serving as Head of Department form In he was chair of the British Geomorphological Research Group; when the group was re-established as the British Society for Geomorphology he was elected as one of the founding Fellows, in He was a member of the REF and RAE Geography subpanels and has been a member of similar discipline and university sector reviews overseas.
Despite undertaking many internal university and external administrative and executive roles, as well as leading major research projects, David Thomas maintains a significant teaching and doctoral supervision profile and is a member of the management committee of Oxford’s NERC-DTP. To date he has supervised over 35 doctoral students to completion, including many now in their own, often senior, academic posts. Most projects employ rigorous fieldwork to generate empirical datasets from environmental contexts that are data-poor.
The ADB samples were extracted from macroscopically homogeneous silt-rich deposits Fig. For the populations of Online dating la gi Europe, which was not directly affected, the main consequence online dating la gi the explosion would have been online dating la gi bring about a release from the constraints of demographic pressure induced datin the continental landmass by the previous millennia of population growth and Neandertal assimilation.
Samples were from four deserts in northern China, namely Hulun Buir, Mu Us, Hobq and Horqin. The deserts are located in the semiarid climatic zone, controlled by the East Asian monsoon circulation. The deserts are located in the semiarid climatic zone, controlled by the East Asian monsoon circulation.
He had been a middle school teacher geography for two years ; and stayed in Physical Research Lab in India hosted by Prof. As a scholar in Oxford University, he was entitled to dine at the high table in the college. Environmental change in arid and semi-arid areas the Tibetan Plateau, the Chinese Loess Plateau, deserts and salt lakes in north-western China, etc ; Chronology of human migration; Luminescence dating in both application and technique development. Lai enjoys his hobbies reading and sporting, etc.
Updated in May PhD students under supervision: Master students under supervision: Journal of Quaternary Science, submitted. Journal of Asian Earth Sciences, revised. Luminescence dated aeolian deposits of late Quaternary age in the southern Tibetan Plateau and their implications for landscape history. Quaternary Geochronology, in press. Late Pleistocene genesis of the middle Yarlung Zhangbo Valley, southern Tibet China , as deduced by sedimentological and luminescence data.