Analysis of strain‐induced ground‐water fluctuations at Devils Hole,Nevada

The pool in Devils Hole is a sensitive indicator of crustal strain and fluctuates in response to changes in atmospheric pressure, earth tides, earthquakes, large‐scale tectonic activity and ground‐water development. Short‐term and cyclic water‐level fluctuations caused by atmospheric pressure and earth tides were found to be on the order of millimeters to centimeters. The 1992 Landers/Little Skull Mountain earthquake sequence and the 1999 Hector Mine earthquake induced water‐level offsets of greater than ?12 and ?3.6 cm, respectively. The results of a dislocation model used to compute volumetric strain for each earthquake indicates that the coseismic water‐level offsets are consistent in magnitude and sense with poroelastic responses to earthquake‐induced strain. Theoretical postseismic fluid‐flow modeling indicates that the diffusivity of the system is on the order of 0.03 m² sec^?1, and identified areas of anomalous water‐level fluctuations. Interpretation of model results suggests that while the persistent post‐Landers rise in water‐level can be attributed to deformation‐induced channeling of fluid to the Devils Hole fault zone, the cause of the pre‐Hector Mine water‐level rise may be related to postseismic excess fluid pressures or preseismic strain accumulation.     

Mapping Local‐Scale Ecological Research to Aid Management at Landscape Scales

Natural resource management is typically defined by landscape‐scale management zones, such as the Catchment Management Authority boundaries of the southern Murray‐Darling Basin in Australia. Ecological research generally deals with local‐scale phenomena, with studies at the scale of such landscape management units arising only recently. We developed a method that links local‐scale ecological research to landscape‐scale management zones, which is presented here as a geographical bibliographic database. This research proceeded in four phases. First, we assessed three decades of ecological research in the Goulburn‐Broken Catchment in Victoria, Australia, using this method, revealing the locations where research has taken place across the landscape, and the research themes dominant in different bioregions. Second, we assessed the purposes to which the method could be applied. Third, we tested the method against one of these potential purposes to review ecological research in a subcatchment case study. Last, we interrogated the method to answer an ecological question. This methodological analysis demonstrated that mapping ecological research in this way allows the user to identify geographic gaps in research coverage, assist in limiting search results to a location of interest and to address location‐specific ecological questions. In combination with landscape classification methods, such as biogeographic regionalisation units, this method can be used to evaluate research coverage across similar ecological communities.     

Investigating absence: Assessing the cumulative effects of casual collecting at a 19th century Bahamian plantation

Abstract

Recent archaeological work at Prospect Hill, a 19th century plantation in the Bahamas, revealed artifact patterns that are inconsistent with expectations for a plantation site. The quantity and quality of artifacts in residential areas associated with the planter family and the enslaved population were inverted and suggest significant post abandonment changes. The site of Prospect Hill has been a destination for tourists and student groups since the mid-20th century, and the areas of the site most accessible to these visitors are also those with surprisingly low artifact counts. I investigated the possibility that regular visitation involved casual collecting using historical data as well as artifact assemblages from archaeological work at Prospect Hill. My analysis suggests that the archaeological record has been altered significantly through casual, opportunistic collecting, and it offers insights for identifying casual collecting elsewhere.     

Geoarchaeological investigations at Diepkloof Rock Shelter,Western Cape,South Africa

The sedimentary sequence at Diepkloof Rock Shelter formed through a complex interaction of depositional and post-depositional processes and was variously influenced by biogenic, geogenic, and anthropogenic agents. Here, we present the results of a micromorphological study of the sediments at Diepkloof, focusing in particular on the numerous anthropogenic inputs and modifications recorded within the sequence. By applying the microfacies concept, we were able to identify hearth burning and maintenance, bedding construction and burning, and surface modification by trampling as major processes that contributed to the formation of the site. The human activities recorded within the sediments show a marked change throughout the sequence, implying a shift in the use of the site over time. The present study also provides a context for evaluating other classes of artifacts and data collected from the site.     

Application of GIS methods to retrieve orientation patterns from imagery; a case study from Beds I and II,Olduvai Gorge (Tanzania)

The role of natural processes in the formation of the Bed I and II sites at Olduvai Gorge (Tanzania) remains the subject of much debate, five decades after their original excavation. Preferred orientation of items is indicative of water disturbance, but compass bearings were not available in Mary Leakey's (1971) study. Using GIS methods, we have vectorized maps from 1960s excavations at Olduvai, and applied a range of statistical techniques to calculate items strike. The GIS analysis suggests strongly preferred orientation patterns in Bed I, and more heterogeneous angular histograms in Bed II. Two complementary lines of evidence support these results. Firstly, modelling of potential mapping errors provides a large interval of confidence for preferred orientation patterns. Second, the GIS study was extended to photographs of the earlier excavations and to maps from recent fieldwork at Olduvai; both yielded patterned arrangement of lithics and bones, and are consistent with results based on the analysis of the 1960s maps, i.e. a large number of the Bed I and II assemblages are preferentially oriented. These results highlight the potential of GIS applications to the analysis of imagery in Stone Age studies, and bear important implications for the understanding of the role of natural agents in site formation processes at Olduvai.     

Particle size distribution of lithic assemblages and taphonomy of Palaeolithic sites

Lithic debris derived from knapping and used tools can be assimilated to simple sedimentary particles that may undergo size sorting when exposed to geomorphic processes such as streamflow or overland flow. Sorting can be identified by comparing the size distribution of archaeological assemblages to that of experimental core reduction sequences. A new database including different types of raw material (mainly flint and quartzite) and Palaeolithic debitage (blade, Levallois, discoid, on anvil, and shaping) has been built for this purpose. Palaeoeskimo data have also been added to illustrate microlithic industries. For all the debitages and raw materials, the particle size of knapping products >2 mm in width fits with a power-law distribution and shows only minor fluctuations, the range of which is always <15% between experiments (all steps of the chaîne opératoire included up to the final tool). A lithic assemblage derived from block/core knapping or blank/preform production will display a particle size distribution close to the experimental distributions if not subsequently modified. Modifications may originate either from sedimentary processes or from anthropogenic factors. To help distinguishing amongst these, data on the impact of both water flows on sedimentary particles or experimental assemblages, and anthropogenic processes such as importation-exportation (of core, preforms or finished tools) or uneven spatial distribution of the different steps in core reduction and tool production within a site, are reviewed. By contrast to anthropogenic modifications, sedimentary processes are generally typified by strong impoverishment in or selective accumulation of fine-grained (<10 mm) artefacts together with a low intra-site variability (spatial homogenization) or a downslope size trend. Archaeological case studies taken from French Palaeolithic site are then detailed. Evidence for lithic redistribution implies that care should be taken in archaeological site analysis since sorting may impact significantly the initial techno-typological balance of the assemblage.     

Scotland's coast: Understanding past and present processes for sustainable management

The coastline of Scotland is extremely long and varied. It comprises most of the major types of coastal environment and includes machair, a sand dune system that is unique to the western seaboard of the British Isles. Such variety has its roots in the geology and sea level inheritance of Scotland and demonstrates that long‐term processes still exert a profound influence on coastal form and functioning. Understanding how these processes affect the coast and influence such diversity is essential to efficient coastal management, although it is also imperative that the vision, strategy and political will to deliver such management are also in place.     

Neolithic settlement patterns in temperate Europe: Progress and problems

The study of settlement patterns must be accompanied by careful evaluation of the processes of formation of the archaeological record and of its recovery. A selective review is offered of Neolithic case studies from central and western Europe, from theLinearbandkeramik culture (fifth millennium bc) to Denmark and Britain (fourth and third millennia bc). The emphasis of the study is upon dispersed settlement patterns. Possibilities of specialization and hierarchy are discussed. Settlement studies should be further exploited for the system, or social rules and contexts, that may be inferred from the patterning of settlements.     

Identification and assessment of secondary refuse aggregates

Secondary refuse contains a wealth of information on the people who generated it. This article identifies some means by which archaeologists can identify and characterize secondary refuse aggregates — localized, high-density deposits of artifacts that have been discarded away from their place of use. A variety of studies of archaeological deposits — from prehistoric and historical archaeology, ethnoarchaeology, and modern material culture studies — provides hypotheses and a comparative database for discussion. I suggest that socioeconomic and demographic factors operating in a society greatly affect the composition of secondary refuse aggregates and propose some hypotheses regarding the directions and magnitudes of these relationships.