Enhancing understanding of breakdown and collapse in the Yorkshire Dales using ground penetrating radar on cave sediments     

P. Murphy  A.R. Westerman  R. Clark  A. Booth  A. Parr 《Engineering Geology》2008,99(3-4):160

Historical evidence shows block breakdown and collapse are actively occurring in large fault aligned caverns in the Yorkshire Dales karst. Deployment of ground penetrating radar at two such sites has provided detailed images of the sedimentary sequences below the present day cavern floor but no large blocks are imaged within the sediments. Solutional processes must be removing limestone from the sediment to allow continued cavern growth. Possible mechanisms to account for the lack of large blocks within the sediment fill are discussed.  相似文献   

Naming names: brief thoughts on disability and geography     

Hester Parr 《Area》1997,29(2):173-176

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Atmospheric sensitivity to roughness length in a regional atmospheric model over the Ohio–Tennessee River Valley     

Arturo I. Quintanar  Rezaul Mahmood  Astrid Suarez  Ronnie Leeper 《Meteorology and Atmospheric Physics》2016,128(3):315-330

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Benthic Carbon Mineralization and Nutrient Turnover in a Scottish Sea Loch: An Integrative In Situ Study   总被引：1，自引：1，他引：0  

Ronnie N. Glud  Peter Berg  Henrik Stahl  Andrew Hume  Morten Larsen  Bradley D. Eyre  Perran L. M. Cook 《Aquatic Geochemistry》2016,22(5-6):443-467

Based on in situ microprofiles, chamber incubations and eddy covariance measurements, we investigated the benthic carbon mineralization and nutrient regeneration in a ~65-m-deep sedimentation basin of Loch Etive, UK. The sediment hosted a considerable amount of infauna that was dominated by the brittle star A. filiformis. The numerous burrows were intensively irrigated enhancing the benthic in situ O₂ uptake by ~50 %, and inducing highly variable redox conditions and O₂ distribution in the surface sediment as also documented by complementary laboratory-based planar optode measurements. The average benthic O₂ exchange as derived by chamber incubations and the eddy covariance approach were similar (14.9 ± 2.5 and 13.1 ± 9.0 mmol m^?2 day^?1) providing confidence in the two measuring approaches. Moreover, the non-invasive eddy approach revealed a flow-dependent benthic O₂ flux that was partly ascribed to enhanced ventilation of infauna burrows during periods of elevated flow rates. The ratio in exchange rates of ΣCO₂ and O₂ was close to unity, confirming that the O₂ uptake was a good proxy for the benthic carbon mineralization in this setting. The infauna activity resulted in highly dynamic redox conditions that presumably facilitated an efficient degradation of both terrestrial and marine-derived organic material. The complex O₂ dynamics of the burrow environment also concurrently stimulated nitrification and coupled denitrification rates making the sediment an efficient sink for bioavailable nitrogen. Furthermore, bioturbation mediated a high efflux of dissolved phosphorus and silicate. The study documents a high spatial and temporal variation in benthic solute exchange with important implications for benthic turnover of organic carbon and nutrients. However, more long-term in situ investigations with like approaches are required to fully understand how environmental events and spatio-temporal variations interrelate to the overall biogeochemical functioning of coastal sediments.  相似文献   

Swedish Svecofennian ore deposits     

K. Sundblad  J. M. Parr 《Mineralium Deposita》1994,29(2):109-109

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Branch migration and the international dispersal of families     

Parr N  Lucas D  Mok M 《International journal of population geography : IJPG》2000,6(3):213-227

This paper discusses the dispersal of facilities where family members migrate to different destination countries. Terminology for internationally dispersed families is proposed, and the term branch migration is suggested for the migration of related people from the same source country to different destination countries. Data from two 1993 surveys of senior secondary students show that 22% of Sydney students and 20% of Hong Kong students have relatives in two or more other countries. The data suggest that many Asian migrant families have branched between the US, Canada, Australia and other migrant-receiving nations. The causes and implications of the international dispersal of families are discussed.  相似文献   

Active tectonic morphology and submarine deformation of the northern Gulf of Eilat/Aqaba from analyses of multibeam data   总被引：1，自引：0，他引：1  

Gideon Tibor  Tina M. Niemi  Zvi Ben-Avraham  Abdallah Al-Zoubi  Ronnie A. Sade  John K. Hall  Gal Hartman  Emad Akawi  Abdelrahmem Abueladas  Rami Al-Ruzouq 《Geo-Marine Letters》2010,30(6):561-573

A high-resolution marine geophysical study was conducted during October-November 2006 in the northern Gulf of Aqaba/Eilat, providing the first multibeam imaging of the seafloor across the entire gulf head spanning both Israeli and Jordanian territorial waters. Analyses of the seafloor morphology show that the gulf head can be subdivided into the Eilat and Aqaba subbasins separated by the north-south-trending Ayla high. The Aqaba submarine basin appears starved of sediment supply, apparently causing erosion and a landward retreat of the shelf edge. Along the eastern border of this subbasin, the shelf is largely absent and its margin is influenced by the Aqaba Fault zone that forms a steep slope partially covered by sedimentary fan deltas from the adjacent ephemeral drainages. The Eilat subbasin, west of the Ayla high, receives a large amount of sediment derived from the extensive drainage basins of the Arava Valley (Wadi ’Arabah) and Yutim River to the north–northeast. These sediments and those entering from canyons on the south-western border of this subbasin are transported to the deep basin by turbidity currents and gravity slides, forming the Arava submarine fan. Large detached blocks and collapsed walls of submarine canyons and the western gulf margin indicate that mass wasting may be triggered by seismic activity. Seafloor lineaments defined by slope gradient analyses suggest that the Eilat Canyon and the boundaries of the Ayla high align along north- to northwest-striking fault systems—the Evrona Fault zone to the west and the Ayla Fault zone to the east. The shelf–slope break that lies along the 100 m isobath in the Eilat subbasin, and shallower (70–80 m isobaths) in the Aqaba subbasin, is offset by approx. 150 m along the eastern edge of the Ayla high. This offset might be the result of horizontal and vertical movements along what we call the Ayla Fault on the east side of the structure. Remnants of two marine terraces at 100 m and approx. 150 m water depths line the southwest margin of the gulf. These terraces are truncated by faulting along their northern end. Fossil coral reefs, which have a similar morphological appearance to the present-day, basin margin reefs, crop out along these deeper submarine terraces and along the shelf–slope break. One fossil reef is exposed on the shelf across the Ayla high at about 60–63 m water depth but is either covered or eroded in the adjacent subbasins. The offshore extension of the Evrona Fault offsets a fossil reef along the shelf and extends south of the canyon to linear fractures on the deep basin floor.  相似文献   

The NASA Lunar Impact Monitoring Program     

Robert M. Suggs  William J. Cooke  Ronnie J. Suggs  Wesley R. Swift  Nicholas Hollon 《Earth, Moon, and Planets》2008,102(1-4):293-298

NASA’s Meteoroid Environment Office has implemented a program to monitor the Moon for meteoroid impacts from the Marshall Space Flight Center. Using off-the-shelf telescopes and video equipment, the Moon is monitored for as many as 10 nights per month, depending on weather. Custom software automatically detects flashes which are confirmed by a second telescope, photometrically calibrated using background stars, and published on a website for correlation with other observations. Hypervelocity impact tests at the Ames Vertical Gun Range facility have begun to determine the luminous efficiency and ejecta characteristics. The purpose of this research is to define the impact ejecta environment for use by lunar spacecraft designers of the Constellation manned lunar program. The observational techniques and preliminary results will be discussed. The U.S. Government's right to retain a non-exclusive, royalty-free license in and to any copyright is acknowledged.  相似文献   

The Landscape of GIScience Publications 1997–2007: An Empirical Investigation with Latent Semantic Analysis     

David A. Parr  Yongmei Lu 《Transactions in GIS》2010,14(5):689-708

This article reports on an empirical study of the trends and patterns of research activities in Geographic Information Science (GIScience) during the years 1997–2007. The GIScience research priorities identified by the University Consortium of Geographic Information Science (UCGIS) were used as guidelines to examine the 985 research articles published in six well‐recognized academic journals. Latent Semantic Analysis (LSA) was employed to investigate the association among the different GIScience research themes. The spatial and temporal patterns of the association between the publications and the different GIScience themes were examined to show the development of GIScience research during the study period. Furthermore, correlation analyses between the publications were conducted following the LSA results to reveal GIScience research networks, including the networks of the published articles and those formed by the research places. In this article, we applied an approach that was developed within information science to depict what GIS research activities were conducted when and where and how they connect to each other through sharing common research themes. The related findings pave the way for future efforts to describe the paradigm of GIScience as well as the pattern of GIScience research.  相似文献   

Effect of fire on phytolith coloration     

Jeff F. Parr 《Geoarchaeology》2006,21(2):171-185

Dark‐colored phytoliths are often found preserved in paleosols and archaeological sediments. Some practitioners believe these darkened phytoliths provide evidence of fire histories, while others suggest alternative reasons for their occurrence. This study examines the effect of fire on phytolith appearance and discusses the extent to which color may be used as proxy evidence for fire. The results of this study demonstrate that under oxidative conditions of openair fire, the color of phytoliths can be altered, although dark‐colored phytoliths also occur naturally in some unburned plant species. Despite some overlap observed between burned and unburned color in phytoliths, clear differences are apparent in the way this color appears optically. In particular, transparent and opalescent qualities were found to occur in nature as opposed to a dull opaque appearance of charred phytoliths. Although fire‐induced color change is probably limited to a portion of the phytolith assemblage, phytolith color remains a tool that can be confidently used to indicate the presence of fire in various sedimentary contexts. © 2006 Wiley Periodicals, Inc.  相似文献