On the origin and the tectonic implications of magnetic overprinting of the Old Red Sandstone, Shetland     

T. H. Torsvik  B. A. Sturt  D. M. Ramsay 《Geophysical Journal International》1989,99(3):749-759

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Marine geology of the Sodwana Bay shelf, southeast Africa     

P.J Ramsay 《Marine Geology》1994,120(3-4):225-247

The geostrophic current-controlled northern Zululand shelf displays a unique assemblage of interesting physical, sedimentological and biological phenomena. The shelf in this area is extremely narrow (3 km) and is characterised by submarine canyons, coral reefs, and steep gradients on the continental slope. Three submarine canyons occur in the study area and are classified as mature- or youthful-phase canyons depending on the degree to which they breach the shelf. These canyons originated as mass-wasting features which were exploited by palaeo-drainage during sea-level regressions. Shelf lithology is dominated by a series of coast-parallel patch coral reefs which have colonised beachrock and aeolianite sequences that extend semi-continuously from −5 to −95 m, and delineate late Pleistocene palaeocoastline events. The unconsolidated sediment on the shelf is either shelf sand (mainly terrigenous quartz grains) or bioclastic sediment. Large-scale subaqueous dunes commonly form in the unconsolidated sediment on the outer-shelf due to the Agulhas Current flow. These dunes occur as two distinct fields at depths of −35 to −70 m; the major sediment transport direction is towards the south, but occasional bedload parting zones exist where the bedform migration direction changes from south to north.  相似文献   

An assessment of the acoustic survey technique, RoxAnn, as a means of mapping seabed habitat   总被引：1，自引：3，他引：1  

Greenstreet  Simon P. R.; Tuck  Ian D.; Grewar  Gavin N.; Armstrong  Eric; Reid  David G.; Wright  Peter J. 《ICES Journal of Marine Science》1997,54(5):939-959

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Data-driven estimation of building interior plans     

Julian F. Rosser  Gavin Smith  Jeremy G. Morley 《International journal of geographical information science》2017,31(8):1652-1674

This work investigates constructing plans of building interiors using learned building measurements. In particular, we address the problem of accurately estimating dimensions of rooms when measurements of the interior space have not been captured. Our approach focuses on learning the geometry, orientation and occurrence of rooms from a corpus of real-world building plan data to form a predictive model. The trained predictive model may then be queried to generate estimates of room dimensions and orientations. These estimates are then integrated with the overall building footprint and iteratively improved using a two-stage optimisation process to form complete interior plans.

The approach is presented as a semi-automatic method for constructing plans which can cope with a limited set of known information and constructs likely representations of building plans through modelling of soft and hard constraints. We evaluate the method in the context of estimating residential house plans and demonstrate that predictions can effectively be used for constructing plans given limited prior knowledge about the types of rooms and their topology.  相似文献   

Using oocyte size to assess seasonal ovarian development in Solea solea (L.)     

K. Ramsay  P. Witthames 《Journal of Sea Research》1996,36(3-4)

Maximum oocyte size was used to assess seasonal ovarian development in sole. Fish age, especially the adolescent period, appeared to affect the start of vitellogenin-dependent oocyte development in the annual reproductive cycle and the subsequent oocyte growth rate. The majority of oocyte growth occurred between September and March. Several other aspects of ovarian development were also age-dependent, including the increase in ovary condition factor (ovary weight/fish length³) and the size of oocytes commencing nuclear migration. Evidence is presented that in the recruiting year class of sole abortive maturation occurs where oocytes develop yolk but spawning does not take place. The implications of this study on the estimation of female spawning stock biomass are discussed.  相似文献   

Environmental economic geography: A sympathetic critique   总被引：4，自引：0，他引：4  

Gavin Bridge 《Geoforum》2008,39(1):76-81

In this article I examine the objectives and substantive claims of a body of work that has come to be known as ‘environmental economic geography’ (EEG). I characterize this loose grouping of research activities as a topical contrivance: often what unites EEG researchers is simply a desire to apply the theories and methods of economic geography to environmental issues. The article explores an alternative rationale for doing EEG: the development of a distinctive intellectual project out of the encounter between economic geography and environment. Such a project extends beyond an assessment of the environmental impacts of economic activity, to examine the ways in which many ‘economic’ processes are environmentally constituted.  相似文献   

Global Resource Assessments of Primary Metals: An Optimistic Reality Check     

Gavin M. Mudd  Simon M. Jowitt 《Natural Resources Research》2018,27(2):229-240

The mining of primary metals is critical for a range of modern infrastructure and goods and the continuing growth in global population and consumption means that these primary metals are expected to remain in high demand. However, metallic deposits are, in essence, finite and non-renewable—leading to some concern that we may run out of a given metal in the future. Here, we address this concern by presenting a brief review of the reporting of mineral resource estimates, compiling detailed datasets for national and global trends in mineral resources for numerous metals, and present detailed case studies of major mining projects or fields. The evidence clearly shows strong growth in known mineral resources and cumulative production over time rather than any evidence of gradual resource depletion. In addition, the key factors that already govern existing mining projects and mineral resources are certainly social, environmental and economic in nature rather than geological or related to physical resource depletion. Overall, there is great room for optimism in terms of humankind’s ability to supply future generations with the metals they will require.  相似文献   

Modeling postglacial vegetation dynamics of temperate forests on the Olympic Peninsula (WA,USA) with special regard to snowpack     

Christoph Schwörer  David M. Fisher  Daniel G. Gavin  Christian Temperli  Patrick J. Bartlein 《Climatic change》2016,137(3-4):379-394

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Chronology,stratigraphy and palaeoenvironmental interpretation of a Late Pleistocene to mid‐Holocene cave accumulation on Kangaroo Island,South Australia     

Matthew C. McDowell  Erick A. Bestland  Fiona Bertuch  Linda K. Ayliffe  John C. Hellstrom  Geraldine E. Jacobsen  Gavin J. Prideaux 《Boreas: An International Journal of Quaternary Research》2013,42(4):974-994

Chronological, sedimentological and geochemical analyses of a clastic infill from Kelly Hill Cave (5K1), Kangaroo Island, document a palaeoenvironmental record that spans from the Late Pleistocene to the middle Holocene. We AMS radiocarbon‐dated bone collagen and U–Th‐dated speleothem to determine that fossiliferous sediments were deposited between >20 ka and 7 ka ago. Most of the 15 sedimentary layers are dominated by sand‐ and silt‐sized quartz that is physically and geochemically comparable with surface soils in the Kelly Hill area. Late Pleistocene and Last Glacial Maximum strata are represented primarily by homogeneous, poorly sorted quartz‐rich sediments that contain little organic matter, but include a thin layer composed largely of silt‐sized clay pellets that resemble sediments deflated from playa lakes. Microstructures observed in petrographic slides indicate that, with the exception of one layer, all sediments experienced little reworking once deposited in the cave. Some layers display pedogenic microstructures such as redeposited clays and opaline silica infilling that indicate postdepositional modification; that is, cave‐floor soil development. Overlying Holocene‐aged sediments also consist mainly of quartz but have much greater organic matter content. Some of these sediments have been strongly influenced by re‐precipitated organic matter that appears to have been transported into the cave via vadose drip water. The presence of dissolved organic matter in soil/vadose waters suggests a high vegetation density and acidic soils, which are congruent with the more equitable climatic conditions characteristic of the Holocene. The sediments described here provide a valuable palaeoenvironmental record that will facilitate future interpretation of associated vertebrate fossils.  相似文献   

Climate change impacts on extreme floods I: combining imperfect deterministic simulations and non-stationary frequency analysis     

Ousmane Seidou  Andrea Ramsay  Ioan Nistor 《Natural Hazards》2012,61(2):647-659

Flood quantiles are routinely used in hydrologic engineering to design hydraulic structures, optimize erosion control structure and map the extent of floodplains. As an increasing number of papers are pointing out cycles and trends in hydrologic time series, the use of stationary flood distributions leads to the overestimation or underestimation of the hydrologic risk at a given time. Several authors tried to address this problem by using probability distributions with time-varying parameters. The parameters of these distributions were assumed to follow a linear or quadratic trend in time, which may be valid for the short term but may lead to unrealistic long-term projections. On the other hand, deterministic rainfall-runoff models are able to successfully reproduce trends and cycles in stream flow data but can perform poorly in reproducing daily flows and flood peaks. Rainfall-runoff models typically have a better performance when simulation results are aggregated at a larger time scale (e.g. at a monthly time scale vs. at a daily time scale). The strengths of these two approaches are combined in this paper where the annual maximum of the time-averaged outputs of a hydrologic model are used to modulate the parameters of a non-stationary GEV model of the daily maximum flow. The method was applied to the Kemptville Creek located in Ontario, Canada, using the SWAT (Soil and Water Assessment Tool) model as rainfall-runoff model. The parameters of the non-stationary GEV model are then estimated using Monte Carlo Markov Chain, and the optimal span of the time windows over which the SWAT outputs were averaged was selected using Bayes factors. Results show that using the non-stationary GEV distribution with a location parameter linked to the maximum 9-day average flow provides a much better estimation of flood quantiles than applying a stationary frequency analysis to the simulated peak flows.  相似文献