Late Holocene vertical land motion and relative sea‐level changes: lessons from the British Isles     

Ian Shennan  Glenn Milne  Sarah Bradley 《第四纪科学杂志》2012,27(1):64-70

Vertical land motion caused by continuing glacial isostatic adjustment is one of several important components of sea‐level change and is not limited just to previously glaciated regions. A national‐scale analysis for the British Isles shows an ellipse of present‐day relative uplift (relative sea‐level fall), ～1.2 mm a^?1, broadly centred on the deglaciated mountains of Scotland. The pattern of three foci of relative subsidence, ～1 mm a^?1, results from the additional interactions of the deglacial meltwater load on the Atlantic basin and the continental shelf, and the signal due to far‐field ice sheets. At a local scale, sediment compaction can more than double the rate of relative land subsidence. Relative land‐level change (the negative of relative sea‐level change) is not the same as vertical land motion. There is a spatial pattern in the difference between relative land‐level change and vertical land motion, with differences at present of approximately ?0.1 to ?0.3 mm a^?1 around the British Isles and +2.5 to ?1.5 mm a^?1 globally. For the wider scientific and user community, whether or not the differences are considered significant will depend upon the location, time frame and spatial scale of the study that uses such information. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Epikarst hydrology and implications for stalagmite capture of climate changes at Grotta di Ernesto (NE Italy): results from long‐term monitoring     

Renza Miorandi  Andrea Borsato  Silvia Frisia  Ian J. Fairchild  Detlev K. Richter 《水文研究》2010,24(21):3101-3114

Grotta di Ernesto is a cave site well suited for palaeoclimate studies because it contains annually laminated stalagmites and was monitored from 1995 to the end of 2008 for microclimate, hydrology and hydrochemistry. Long‐term monitoring highlighted that cave drips show three different hydrological responses to rainfall and infiltration: (1) fast seasonal drips in the upper part of the cave, which are mostly fed by fractures, (2) slow seasonal drips, located at mid‐depth in the cave characterized by mixed feeding and (3) slow drips, mostly located in the deeper gallery, which are fed by seepage flow from bulk porosity with a minor fracture‐fed component. The slow drips display daily cycles during spring thaw. Monitoring also indicated that drip waters are only slightly modified by degassing within the soil zone and aquifer and by prior calcite precipitation. Hydrochemical studies show a clear seasonality in calcite saturation index, which results in most cave calcite precipitation occurring during late autumn and winter with similar amounts of precipitated calcite on most stalagmites, regardless of drip rate (discharge) differences. Drip rate, and drip rate variability, therefore, has a minor role in modulating the amount of annual calcite formation. In contrast, drip rate, when associated with moderate reduction in calcite saturation index, clearly influences stalagmite morphology. Increasing drip rate yields a passage from candle‐, to cone‐ to dome‐shaped stalagmites. Very high drip rates feed speleothems with flowstone morphology. In summary, monitoring provides information about the karst aquifer and how hydrology influences those physical and chemical characteristics of speleothems which are commonly used as climate proxies. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Determination of the Rare-Earth Elements and Yttrium In 37 International Silicate Reference Materials By Inductively Coupled Plasma-Atomic Emission Spectrometry     

Kym E. JARVIS  Ian JARVIS 《Geostandards and Geoanalytical Research》1988,12(1):1-12

The rare-earth elements (REE) and yttrium have been determined in 37 international rock and mineral reference materials. Samples were prepared using conventional rock-dissolution techniques, and the REE and yttrium were separated from the other constituents using cation-exchange chromatography. The REE (La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Yb, Lu) and yttrium were determined simultaneously by inductively coupled plasma-atomic emission spectrometry (ICP-AES). Results for four well-characterised USGS standard rocks agree favourably with "recommended" values and with REE determinations made previously by workers using ICP-AES, isotope dilution mass spectrometry, instrumental neutron activaton analysis and X-ray fluorescence spectrometry.
Les éléments de terres rares (TR) et yttrium ont été dosés dans 37 échantillons internationaux de réféence. Les échantillons ont été décomposés par dissolution acide et les TR séparés par résine échangeuse de cations. Les TR (La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Yb, Lu) et yttrium ont été dosés simultanément par la spectrométrie d'émission-plasma inductif. Les résultats obtenus pour quatre échantillons de référence bien charactérisés de I'USGS se comparent favorablement avec ceux obtenus par la spectrométrie d'émission-plasma, la dilution isotopique, I'activation neutronique et par la spectrométrie d'é fluorescence-X.  相似文献   

Book reviews     

A. D. Sneyd  W. E. Sharp  Ian Lerche 《Mathematical Geosciences》1989,21(3):395-400

  相似文献   

Hydraulic processes on alluvial fans,R. H. French,Developments in Water Science 31, Elsevier Science Publishers,Amsterdam, 1987. No. of Pages: 244. ISBN 0–444–42781–3     

Ian Reid 《地球表面变化过程与地形》1988,13(7):664-664

  相似文献   

Book reviews     

F. Alejandro Nava  Manfred Koch  Andrzej Hanyga  Jacek Leliwa-Kopystyński  Frazer Tabeart  Sueo Veno  Andrzej W. Wernik  Yu. N. Korenkov  Kenji Satake  Carlos Lozano  Aysel Karafistan  Ian N. James  Anthony Dore  Jacek Wałczewski  Krzysztof Haman  Brian F. Farrell 《Pure and Applied Geophysics》1994,143(4):753-780

  相似文献   

Book reviews     

Edward Theriot  Ian R. Walker 《Journal of Paleolimnology》1994,11(2):205-208

  相似文献   

THE TROPICS: ENVIRONMENTS AND HUMAN IMPACTS UNDERSTOOD AND REINTERPRETED     

Ian Douglas  M.A.  B.Litt.  Ph.D. 《Singapore journal of tropical geography》1994,14(2):103-122

In the 1950s, few people had travelled widely through different parts of the tropics and interpretations on tropical landforms, soils, vegetation and climate largely rested on impressions gained from residence or long sojourns in particular tropical countries. Most academic geography on the tropics was then written by expatriates and lacked the perspective gained from long experience of tropical regions. Particular problems of understanding arose as people attempted to extrapolate from one part of the tropics to another. Since then, understanding has advanced enormously, largely through the efforts of tropical scientists working in their own institutions and through the greater technological ability to study tropical lands both remotely and through easier field access. The establishment of a number of field stations, aimed primarily at the biological sciences, but also facilitating the work of geographers, has been a major stimulus to this effort. Concerns over practical issues, particularly local development and global climatic change have prompted new avenues of research, many of which have been assisted by the great increase in data collection in tropical countries. For the future, South-South dialogue between tropical physical geographers is needed to improve their ability to ask meaningful questions so that they can contribute to teach the rest of their discipline more about serious applied and applicable geography.  相似文献   

Inheritance of smolting phenotypes in backcrosses of hybrid stream-type × ocean-type chinook salmon (Oncorhynchus tshawytscha)     

W. Craig Clarke  Ruth E. Withler  John E. Shelbourn 《Estuaries and Coasts》1994,17(1):13-25

Chinook salmon (Oncorhynchus tshawytscha) are ecologically and geographically differentiated into two life history types: “ocean-type,” which enter estuaries as fry or fingerlings in the first year of life and rear there for up to 6 wk before migrating to sea, and “stream-type,” which migrate seaward as smolts after one or more years in fresh water and are only transient residents in the outer portion of estuaries. Following exposure to a long-day priming photoperiod for 2 mo from the time of first feeding, progeny of stream-type chinook salmon undergo a reduction in growth during summer and remain as parr, whereas progeny of ocean-type chinook salmon and hybrids continue to grow during the summer and develop into underyearling smolts. Male purebred and hybrid F₁ progeny of ocean-type and stream-type chinook salmon were backcrossed to females of both parental populations to examine the segregation of photoperiod-independent (smolt) and photoperiod-dependent (parr) phenotypes among progeny. Results of the backcrosses of the hybrid F₁ males depended on female type. The backcross to ocean-type females produced progeny that were predominantly smolts, whereas progeny from the backcross to stream-type females segregated into approximately equal numbers of smolts and parr. These results are consistent with Mendelian inheritance of a single major gene with two alleles: a dominant allele for the photoperiod-independent phenotype of ocean-type chinook salmon and a recessive allele for the photoperiod-dependent phenotype of stream-type chinook salmon.  相似文献   

Farming ‘practice’ as temporally and spatially situated intersections of biography,culture and social structure     

Emily Phillips  Ian Gray 《The Australian geographer》1995,26(2):127-132

This paper brings anthropological, sociological and geographical perspectives to bear on the problem of farm sustainability and, in particular, the legitimation of sustainable farm practices. It attempts to lay some theoretical foundations for explanation of the adoption of farming practices which may, or may not, promote sustainability. A brief survey of the literature surrounding these issues finds many of the current theoretical perspectives incapable of fully accounting for the complexity of farming practice. Reductionist decision/rational‐action models, in particular, are found wanting for their lack of both cultural consistency and social/spatial specificity. Instead, this paper promotes a generative structuralist approach directed towards an analysis of social and economic practice in lived space; that is, firmly anchored in long‐term ethnographic research.  相似文献