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Rip currents as a geological tool 总被引：2，自引：0，他引：2
MICHA&#; GRUSZCZY&#;SKI§ STANIS&#;AW RUDOWSKI† JULIA SEMIL‡ JAN S&#;OMI&#;SKI† JERZY ZROBEK‡ 《Sedimentology》1993,40(2):217-236
This paper considers the nature and sedimentary significance of rip currents. Rip currents are the main factor responsible for the transport of coarse sediments from the littoral zone to greater depths. Such sediments, deposited outside the zone of wave deformation, may be identified as storm rip current increments within sediments deposited during fair weather. Composite beds deposited during a given wave cycle by storm rip currents are closely similar to ‘turbidites’ and many so called ‘fluxo-turbidites’ described from flysch deposits. Using data gathered in studies conducted on the modern Baltic coast, supplemented by experimental work and theoretical considerations, a sedimentary model is proposed. The model may be used to interpret possible rip current deposits among shallow water ‘turbidites’, and both modern storm sediments and ancient ‘tempestites’. 相似文献
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The methods PARAFAC and three-way PLS are compared with respect to their ability to predictreversed-phase retention values.Special attention is paid to simple validatory tools,the meaning and useof which are explained.The simple validatory tools consist of percentages of explained variation in the training set and thosethat can be calculated with the use of markers.These markers are special(reference)solutes,the retentionvalues of which are used to gain information about a new object for which predictions are wanted.Different validatory tools can be calculated with the use of these marker retention values:percentagesof used variation and mean sum of squared residuals after applying the model to these marker retentionvalues.The validatory tools are evaluated on their power to estimate their test set counterparts:thepercentages of explained variation in the test set and mean sum of squared prediction errors in the test set.Two different data sets from reversed-phase chromatography are used to evaluate the validatory tools.The first data set has a high signal-to-noise ratio and is measured under the same measurementconditions.The second data set has a low signal-to-noise ratio and is measured under differentmeasurement conditions.Some of the simple validatory tools seem to have relevance to their test setcounterparts,even in the case of the second data set. 相似文献
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Geomorphological analysis of a digital elevation model reveals an extensive zone with uniformly oriented elongated landforms in the middle and eastern Wielkopolska Lowland, directly to the north of the maximum extent of the Weichselian Ice Sheet. Individual linear landforms are up to 10 km long, a few hundred metres wide, and with only a few metres of relief. The belts of linear landforms visible on the surfaces of the uplands are disrupted by subglacial channels and younger river valleys. The character and distribution of both landform types, in relation to the outlines of marginal zones of the Weichselian ice lobes, indicate that their origin was subglacial. The elongated landforms are interpreted as mega-scale glacial lineations (MSGLs) characteristic of palaeo-ice stream zones. The MSGLs occur in a zone 70 km long and 80 km wide and are distinctly divergent towards the maximum extent of the ice sheet. This arrangement demonstrates that they are the record of the terminal zone of the ice stream, whose full size was likely in the order of a few hundred kilometres in length. 相似文献
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This introductory paper lays the basis for this supplementary issue by briefly presenting the state of knowledge on the KwaZulu-Natal (KZN) Bight at the start of this multi-disciplinary, multi-institutional, ship-based research project that ran from 2009 to 2013. The rationale and aims of the project are also described. The project was a major component of the South African Department of Science and Technology’s African Coelacanth Ecosystem Programme (ACEP), which has been prominent in supporting research on the east coast of South Africa and the wider South-West Indian Ocean. Pivotal to this was the RS Algoa, which was made available for two 30-day surveys (winter and summer) in the KZN Bight by the Department of Environmental Affairs. Although some aspects of the bight ecology are known, much of the research is dated and fragmented, and required refreshing and consolidation in order to produce a platform upon which the understanding of the region’s ecosystem functioning could be established. Much of the oceanographic knowledge is also dated, with no dedicated surveys and significant measurements undertaken since 1989. The overarching theme of the KZN Bight project was to examine the relative importance of sources of nutrients to the central KZN coast and how these are taken up and recycled in the ecosystem, and to describe aspects of the benthic biodiversity, which is poorly described in much of this region. An ambitious project, its accessibility to a ship-based research platform and the diverse scientific skills of the participating scientists allowed considerable success, as reflected in the papers that follow. 相似文献
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MICHA&#; GRADZI&#;SKI RZEJ GÓRNY ANNA PAZDUR MIECZYS&#;AW F. PAZDUR 《Boreas: An International Journal of Quaternary Research》2003,32(3):532-542
Black coloured laminae have been detected inside speleothems from nine caves situated in the Kraków-Wieluń Upland. The black colour results from the occurrence of charcoal particles and organic compounds. These particles originated inside the caves during wood combustion caused by prehistoric human activity. The ultrastructures of charcoal particles prove that most originated in temperatures ranging from 400 up to 600°C, suggesting that the charcoal is connected with domestic fires rather than torches. Although the laminae are proof of human activity in the caves, the occurrence of one particular lamina cannot be associated with a single episode of human occupation. It is due to the fact that depositional processes and corrosion control the number and thickness of the laminae discussed. The presence of black coloured laminae within the studied Holocene speleothems indicates that the investigated caves were settled in the Neolithic, the Bronze Age and later periods. This is consistent with the former archaeological data. 相似文献
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GEOMORPHOLOGICAL CHANGES WITHIN A HILLSLOPE CAUSED BY A WINDTHROW EVENT IN THE TATRA MOUNTAINS,SOUTHERN POLAND 
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下载免费PDF全文 DARIUSZ STRZYŻOWSKI JOANNA FIDELUS MIROSŁAW ŻELAZNY 《Geografiska Annaler: Series A, Physical Geography》2016,98(4):347-360
Tree uprooting plays an important role in hillslope evolution. The geomorphological impact of tree uprooting after a foehn wind occurrence, in December 2013 in the Tatra Mountains, was investigated. Geomorphological mapping was conducted in three watersheds. Additionally, in one of the watersheds, 459 windthrow pits were measured, in an area of 6.4 ha. The mean volume of a pit was 2.41 m3, and the mean surface area was 5.47 m2. 3.9% of the area was affected by windthrow pits, however locally the magnitude of changes was significantly higher, reaching up to 14.5% of the surface area. Slope inclination weakly influenced the effects of uprooting, and a decrease in the average depth of pits on steep slopes was observed. Individual windthrow pits (five cases) initiated the activity of geomorphological processes, and two cases of periodic springs were noted. Changes in the relief of small landforms caused by tree uprooting were documented. Windthrow creation facilitated the delivery of the soil material from the slopes into the channels. 相似文献
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