Using Soil Magnetic Properties to Determine the Onset of Pleistocene Human Settlement at Gledswood Shelter 1, Northern Australia     

Kelsey M. Lowe  James Shulmeister  Joshua M. Feinberg  Tiina Manne  Lynley A. Wallis  Kevin Welsh 《Geoarchaeology》2016,31(3):211-228

In regions that lack built structures or stratified open archaeological sites, such as precolonial Australia, rockshelters are a major source of detailed information for understanding the nature and timing of human occupation. A key concern is that the proposed ages for the earliest archaeological sites are based on luminescence dating of sediments, rather than directly of cultural materials, leaving the association between the sediments and evidence of human activity questionable. Here, we present evidence of magnetic enhancement associated with cultural horizons within the deposits of a Pleistocene rockshelter in interior northern Queensland. Soil magnetic studies combined with experimental burning show that magnetically enhanced sediments in Gledswood Shelter 1 are the result of anthropogenic burning of hearth fires, which burn hotter and for a longer time than natural wild fires. These techniques appear to work in this setting because of the nature of the local geology and the geological antiquity of the landscape. Susceptibility and frequency dependence of susceptibility signatures provide a critical tool to resolve that human occupation starts at 2.2 m depth within a stratigraphic section. In conjunction with luminescence dating, soil magnetic studies provide an opportunity for archaeologists to resolve the timing of human settlement in Australia and other intracratonic plate settings.  相似文献   

U-Th-Pb and Trace Element Evaluation of Existing Titanite and Apatite LA-ICP-MS Reference Materials and Determination of 208Pb/232Th-206Pb/238U Date Discordance in Archaean Accessory Phases     

Omar Khalil Droubi  Ann M. Bauer  Chloë Bonamici  William O. Nachlas  Michael J. Tappa  Joshua M. Garber  Jesse R. Reimink 《Geostandards and Geoanalytical Research》2023,47(2):337-369

The last decade has seen a marked increase in U-Th-Pb petrochronological studies focused on titanite and apatite. This has motivated the need for detailed, phase-specific method development and well-characterised reference materials with a wide variety of ages and chemical compositions. This study presents new U-Th-Pb isotope and major-, minor- and trace-element mass fraction data for ten titanite and five apatite reference materials based on integrated EPMA, LA-ICP-MS and isotope-dilution (ID) multi-collector (MC)-ICP-MS characterisation. Cross-comparison of EPMA and LA-ICP-MS data for the same titanite reference material suite demonstrates that careful selection of EPMA primary reference materials is necessary to minimise inaccuracies. We further identify a significant X-ray interference when measuring low Ce abundances in Ti-bearing phases and outline a method for its correction. New ID-MC-ICP-MS and LA-ICP-MS data suggest tri-concordance (defined as concordant ages for the ²³⁸U-²⁰⁶Pb, ²³⁵U-²⁰⁷Pb and ²³²Th-²⁰⁸Pb decay systems) of the MKED-1 titanite reference material and demonstrate the reproducibility of ²⁰⁸Pb/²³²Th measurements in some secondary titanite reference materials. Integration of ²⁰⁸Pb/²³²Th results with U-Pb geochronology provides a meaningful tool to help interpret complex U-Th-Pb isotopic age spectra. We provide example applications of ²⁰⁸Pb/²³²Th LA-ICP-MS measurements toward interpreting Archaean titanite ages from the Acasta Gneiss Complex, Northwest Territories, Canada.  相似文献   

Hierarchical livelihood outcomes among co-managed fisheries     

M. Aaron MacNeil  Joshua E. Cinner 《Global Environmental Change》2013,23(6):1393-1401

Collaborative management arrangements are increasingly being used in fisheries, yet critical questions remain about the conditions under which these are most successful. Here, we conduct one of the first comprehensive tests of Elinor Ostrom's diagnostic framework for analyzing social–ecological systems to examine how 16 socioeconomic and institutional conditions are related the livelihood outcomes in 42 co-management arrangements in five countries across the Indo-Pacific. We combine recent developments in both theory and modeling to address three key challenges among comparative studies of social–ecological systems: the presence of a large number of explanatory mechanisms, variables operating at multiple scales, and the potential for interactions among socio-economic and institutional factors. We find that resource users were more likely to perceive benefits from co-management when they are more involved in decisions, were aware that humans are causal agents of change in marine systems, were wealthier, were not migrants, were in villages with smaller populations and older co-management arrangements, and had clearly established boundaries. Critically, we quantify a number of key interactions between: wealth, dependence on marine resources, involvement in decision-making, and population size that have strong implications for co-management success in terms of livelihood benefits. This study demonstrates that context plays a critical but identifiable role in co-management success.  相似文献   

CIVIL RIGHTS MEMORIALS AND THE GEOGRAPHY OF MEMORY. By Owen J. Dwyer and Derek H. Alderman.     

Joshua F. J. Inwood 《Geographical review》2011,101(1):139-140

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Designing ITQ programs for commercial recreational fishing   总被引：1，自引：0，他引：1  

Joshua Abbott  Vishwanie Maharaj  James E. Wilen   《Marine Policy》2009,33(5):766-774

This paper discusses the potential for implementing individual transferable quota (ITQ) schemes in commercial recreational fisheries, focusing particularly on charter and headboat fisheries. After a brief discussion of ITQs in commercial fisheries, the paper discusses the manner in which rents get dissipated in commercial recreational fisheries. Fishing mortality in recreational fisheries is determined as a joint outcome of angler behavior and trip supply. In the recreational sector under open access conditions, there are likely to be too many vessels providing too many trips at prices that are too low. Vessel input configurations are likely to be distorted in a manner that generates excessive fishing mortality. Designing ITQs for recreational fisheries requires consideration of issues not prominent in the design of commercial fisheries. Among the most important is the manner in which angler preferences and types affect overall mortality from both landings and discards. While catch and release fisheries and pure food fish recreational fisheries are relatively easy to manage with recreational ITQs, fisheries with both angler types present difficult monitoring problems that add complexities to ITQ design. Various ways to design programs that account for both landings and discard mortalities and that generate incentives for anglers and vessel owners to reduce discard mortality are discussed.  相似文献   

Landslides control the spatial and temporal variation of channel width in southern Taiwan: Implications for landscape evolution and cascading hazards in steep,tectonically active landscapes          下载免费PDF全文

Brian J. Yanites  Nate A. Mitchell  Joshua C. Bregy  Grace A. Carlson  Kirstyn Cataldo  Margaret Holahan  Graham H. Johnston  Amelia Nelson  Jeffery Valenza  Matthew Wanker 《地球表面变化过程与地形》2018,43(9):1782-1797

Intense precipitation or seismic events can generate clustered mass movement processes across a landscape. These rare events have significant impacts on the landscape, however, the rarity of such events leads to uncertainty in how they impact the entire geomorphic system over a range of timescales. Taiwan is steep, tectonically active, and prone to landslide and debris flows, especially when exposed to heavy rainfall events. Typhoon Morakot made landfall in Taiwan in August of 2009, causing widespread landslides in southern Taiwan. The south to north trend in valley relief in southern Taiwan leads to spatial variability in landslide susceptibility providing an opportunity to infer the long‐term impact of such landslide events on channel morphology. We use pre‐ and post‐typhoon imagery to quantify the propagating impact of this event on channel width as the debris is routed through the landscape. The results show the importance of cascading hazards from landslides on landscape evolution based on patterns of channel width (both pre‐ and post‐typhoon) and hillslope gradients in 20 basins along strike in southern Taiwan. Prior to Typhoon Morakot, the river channels in the central part of the study area were about 3–10 times wider than the channels in the south. Following the typhoon, aggradation and widening was also a maximum in these central to northern basins where hillslope gradients and channel steepness is high, accentuating the pre‐typhoon pattern. The results further show that the narrowest channels are located where channel steepness is the lowest, an observation inconsistent with a detachment‐limited model for river evolution. We infer this pattern is indicative of a strong role of sediment supply, and associated landslide events, on long‐term channel evolution. These findings have implications across a range of spatial and temporal scales including understanding the cascade of hazards in steep landscapes and geomorphic interpretation of channel morphology. Copyright © 2018 John Wiley & Sons, Ltd.  相似文献   

Content driving exposure and attention to tweets during local,high-impact weather events     

Eachus  Joshua D.  Keim  Barry D. 《Natural Hazards》2020,103(2):2207-2229

Natural Hazards - The use of Twitter to disseminate weather information presents need for the analysis of what types of messages, and specifically warning messages, incur exposure and attention....  相似文献   

Spectral properties and mineral compositions of acapulcoite–lodranite clan meteorites: Establishing S‐type asteroid–meteorite connections     

Michael P. Lucas  Joshua P. Emery  Takahiro Hiroi  Harry Y. McSween 《Meteoritics & planetary science》2019,54(1):157-180

Except for asteroid sample return missions, measurements of the spectral properties of both meteorites and asteroids offer the best possibility of linking meteorite groups with their parent asteroid(s). Visible plus near‐infrared spectra reveal distinguishing absorption features controlled mainly by the Fe²⁺ contents and modal abundances of olivine and pyroxene. Meteorite samples provide relationships between spectra and mineralogy. These relationships are useful for estimating the olivine and pyroxene mineralogy of stony (S‐type) asteroid surfaces. Using a suite of 10 samples of the acapulcoite–lodranite clan (ALC), we have developed new correlations between spectral parameters and mafic mineral compositions for partially melted asteroids. A well‐defined relationship exists between Band II center and ferrosilite (Fs) content of orthopyroxene. Furthermore, because Fs in orthopyroxene and fayalite (Fa) content in olivine are well correlated in these meteorites, the derived Fs content can be used to estimate Fa of the coexisting olivine. We derive new equations for determining the mafic silicate compositions of partially melted S‐type asteroid parent bodies. Stony meteorite spectra have previously been used to delineate meteorite analog spectral zones in Band I versus band area ratio (BAR) parameter space for the establishment of asteroid–meteorite connections with S‐type asteroids. However, the spectral parameters of the partially melted ALC overlap with those of ordinary (H) chondrites in this parameter space. We find that Band I versus Band II center parameter space reveals a clear distinction between the ALC and the H chondrites. This work allows the distinction of S‐type asteroids as nebular (ordinary chondrites) or geologically processed (primitive achondrites).  相似文献   

Urban resilience for whom,what, when,where, and why?     

Sara Meerow  Joshua P. Newell 《Urban geography》2019,40(3):309-329

ABSTRACT

In academic and policy discourse, the concept of urban resilience is proliferating. Social theorists, especially human geographers, have rightfully criticized that the underlying politics of resilience have been ignored and stress the importance of asking “resilience of what, to what, and for whom?” This paper calls for careful consideration of not just resilience for whom and what, but also where, when, and why. A three-phase process is introduced to enable these “five Ws” to be negotiated collectively and to engender critical reflection on the politics of urban resilience as plans, initiatives, and projects are conceived, discussed, and implemented. Deployed through the hypothetical case of green infrastructure in Los Angeles, the paper concludes by illustrating how resilience planning trade-offs and decisions affect outcomes over space and time, often with significant implications for equity.  相似文献   

Institutional environments and the livelihood impacts of voluntary sustainability standards: A Village‐based analysis from southern Sumatra's coffee sector     

Joshua G.P. Bray 《Singapore journal of tropical geography》2019,40(2):291-311

Lead roasting firms are operating through Indonesia's coffee exporters to introduce voluntary sustainability standards (VSS) in an attempt to secure supply, and to simultaneously meet corporate social responsibility requirements, even as empirical studies continue to show uncertain benefits for producer livelihoods. Value chain interventions like VSS, however, are not rolled out over a blank canvas, and many contributing factors determine their overall impact on livelihoods, particularly the local institutional environment. This study assesses the extent to which variability of empirical outcomes is determined by the institutional environment, by identifying specific processes through which VSS interact with pre‐existing social, political and economic institutions to influence livelihood outcomes. These include: firm‐specific corporate strategies (including producer training); livelihood strategies of households (including access to assets); government programs; and local political economy, as manifest particularly through patronage between traders and suppliers. VSS have thereby become an additional institutional layer shaping livelihood strategies and regional development outcomes, best viewed as providing access to a new social network that may be exploited by producers. The interaction between VSS programs, livelihood strategies and pre‐existing institutional environments in a particular place often dictates the variable outcomes for producers, making attribution of impact causation to VSS enrolment problematic.  相似文献