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11.
Zsuzsanna Tóth Stephen McCarron Andrew J. Wheeler Stefan Wenau Stephen Davis Aaron Lim Volkhard Spiess 《第四纪科学杂志》2020,35(3):465-478
High-resolution seismic and bathymetric data offshore southeast Ireland and LIDaR data in County Waterford are presented that partially overlap previous studies. The observed Quaternary stratigraphic succession offshore southeast Ireland (between Dungarvan and Kilmore Quay) records a sequence of depositional and erosional events that supports regional glacial models derived from nearby coastal sediment stratigraphies and landforms. A regionally widespread, acoustically massive facies interpreted as the ‘Irish Sea Till’ infills an uneven, channelized bedrock surface overlying irregular mounds and deposits in bedrock lows that are probably earlier Pleistocene diamicts. The till is truncated and overlain by a thin, stratified facies, suggesting the development of a regional palaeolake following ice recession of the Irish Sea Ice Stream. A north–south oriented seabed ridge to the north is interpreted as an esker, representing southward flowing subglacial drainage associated with a restricted ice sheet advance of the Irish Ice Sheet onto the Celtic Sea shelf. Onshore topographic data reveal streamlined bedforms that corroborate a southerly advance of ice onto the shelf across County Waterford. The combined evidence supports previous palaeoglaciological models. Significantly, for the first time, this study defines a southern limit for a Late Midlandian Irish Ice Sheet advance onto the Celtic Sea shelf. © 2020 John Wiley & Sons, Ltd. 相似文献
12.
The aim of this paper was to analyze the ground and low vegetation points of a Light Detection and Ranging (LiDAR) point cloud from the aspect of the generated digital terrain model (DTM). We determined the height difference between the surveyed surface and the DTM and the level of interspersion of ground and low vegetation points in a floodplain. Finally, we performed a supervised classification with topographic (elevation, slope and aspect) variables and an Normalized Difference Vegetation Index (NDVI) layer to identify swales and point bars as floodplain forms. Cross sections of field surveys provided reference data to express the magnitude of the bias on the DTM caused by the vegetation, and we proved that the bias can reach the 60% of the relative height and depth of the floodplain forms (mean error was 0.15 ± 0.12 m). A landscape metric, the Aggregation Index, provided an appropriate tool to analyze and quantify the interspersion of the ground and vegetation points: indicating a high level of interspersion of the classified points, i.e. proved that vegetation points where the last echoes reflected from the vegetation became ground points. Floodplain classification performed best with the common use of DTM, slope, aspect and NDVI coverages, with 71% overall accuracy. 相似文献
13.
Zsuzsanna Varga 《GeoJournal》1998,46(3):215-219
Although agricultural work is declining in Hungary, farming remains an important source of employment. However, the agrarian
population should not be regarded as homogenous because many small farms are worked only for subsistence and family income
supplement. This is because of prolonged economic crisis which makes for a shortage of job opportunities in other sectors
of the economy. Until economic growth accelerates there is a need for transitional solutions to the problem of unemployment.
It is argued that the present farming system could be diversified through labour-intensive programmes to provide piped water
and drainage in small towns and villages and simultaneously engage many of the long-term unemployed who are no longer entitled
to benefit and lack the qualifications for jobs that require special skills. The environment could also be protected by the
afforestation of 300–400 000 ha of arable land or its conversion to grassland. Light industry could also generate employment
while stimulating the growth of local farm production and the improvement of the infrastructure. Training for unemployed young
people should also be a priority if the erosion of rural labour resources is not to become irreversible. A much more proactive
approach is needed from government to safeguard rural labour resources and achieve greater integration between forestry, farming
and processing.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
14.
We determined the quantitative mineralogical compositions of various grain size fractions of soil samples that were collected from 10-cm depth intervals. Our results show that the grain size distribution curve of a given mineral is related to the mineral's origin and can be used as a source of information when soil-forming processes are studied. 相似文献