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The growth of Glasgow from a small town into a heavily industrialised conurbation depended greatly on its local geological riches. Extensive mining and quarrying of a range of minerals took place from the 18th century onwards. The early underground stoop and room (pillar and stall) workings, and the backfilled quarries, together with variably consolidated natural superficial deposits, have bequeathed to the city a heritage of unwanted engineering problems which cannot easily be quantified. Recent work by the British Geological Survey (BGS) illustrates the scale of both geological and man-made problems. 相似文献
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JÓN EIRÍKSSON PETER H. KRISTENSEN HOLGER LYKKE-ANDERSEN KATHRYN BROOKS REW MURRAY KAREN LUISE KNUDSEN CHRISTOPHER GLAISTER 《Boreas: An International Journal of Quaternary Research》2006,35(2):320-331
A unique sequence of Late Saalian, Eemian and Early Weichselian strata is exposed in a coastal outcrop at Mommark in the western Baltic. The sedimentary facies and faunas reflect palaeoenvironmental changes from an initial freshwater lake followed by marine transgression and interglacial deposition in a palaeo-Baltic sea. The upper part of the Eemian marine record indicates regression followed by lacustrine sedimentation and deposition of Early Weichselian aeolian sediments, which are truncated by an erosional unconformity overlain by a till bed. The lower and middle parts of the sequence have previously been correlated with the European glacial-interglacial stratigraphy on the basis of pollen analysis, while the upper part has been dated for the present study using optically stimulated luminescence (OSL) of samples from the aeolian and glacial deposits. A similar complete glacial-interglacial-glacial succession has not previously been recorded from this area. The Mommark sequence of conformable strata has been subjected to lateral compression, evidenced by folding and low-angle reverse faults. Seismic records from the adjacent waters in the western Baltic reveal a system of buried Quaternary valleys in the area. It is suggested that the interglacial deposition took place in a basin within one of these valleys and that a slab constituting the Mommark sequence, originating from the margin of a valley, has been glaciotectonically displaced northwestwards to the present location. 相似文献
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MONA HENRIKSEN JAN MANGERUD ALEXEI MATIOUCHKOV REW S. MURRAY AAGE PAUS JOHN INGE SVENDSEN 《Boreas: An International Journal of Quaternary Research》2008,37(1):20-37
A 22 m long sediment core from Lake Yamozero on the Timan Ridge in northern Russia has provided evidence of intriguing climatic shifts during the last glacial cycle. An overall shallowing of the lake is reflected in the lower part of the cores, where pollen indicates a transition from glacial steppe vegetation to interstadial shrub-tundra. These beds are capped by a well-defined layer of compact clay deposited in relatively deep water, where pollen shows surrounding spruce forests and warmer-than-present summer temperatures. The most conservative interpretation is that this unit represents the last interglacial period. However, a series of Optical Stimulated Luminescence (OSL) dates suggests that it corresponds with the Early Weichselian Odderade interstadial (MIS 5a). This would imply that the Odderade interstadial was just as warm as a normal interglacial in this continental part of northern Europe. If correct, then pollen analysis, as a correlation tool, is less straightforward and the definition of an interglacial is more complex than previously thought. We discuss the validity and possible systematic errors of the OSL dates on which this age model is based, but conclude they really indicate a MIS 5a age for the warm period. Above the clay is an unconformity, most likely reflecting a period of subaerial exposure implying dry conditions. Deposition of silt under fluctuating cold climates in the Middle Weichselian continued until a second gap in the record at c . 40 kyr BP. The lake basin started to fill up again around 18 kyr BP. 相似文献
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The Little Ice Age glacier maximum in Iceland and the North Atlantic Oscillation: evidence from Lambatungnajökull, southeast Iceland 总被引:3,自引:0,他引:3
TOM BRADWELL REW J. DUGMORE DAVID E. SUGDEN 《Boreas: An International Journal of Quaternary Research》2006,35(1):61-80
This article examines the link between late Holocene fluctuations of Lambatungnajökull, an outlet glacier of the Vatnajökull ice cap in Iceland, and variations in climate. Geomorphological evidence is used to reconstruct the pattern of glacier fluctuations, while lichenometry and tephrostratigraphy are used to date glacial landforms deposited over the past ˜400 years. Moraines dated using two different lichenometric techniques indicate that the most extensive period of glacier expansion occurred shortly before c . AD 1795, probably during the 1780s. Recession over the last 200 years was punctuated by re-advances in the 1810s, 1850s, 1870s, 1890s and c . 1920, 1930 and 1965. Lambatungnajökull receded more rapidly in the 1930s and 1940s than at any other time during the last 200 years. The rate and style of glacier retreat since 1930 compare well with other similar-sized, non-surging, glaciers in southeast Iceland, suggesting that the terminus fluctuations are climatically driven. Furthermore, the pattern of glacier fluctuations over the 20th century broadly reflects the temperature oscillations recorded at nearby meteorological stations. Much of the climatic variation experienced in southern Iceland, and the glacier fluctuations that result, can be explained by secular changes in the North Atlantic Oscillation (NAO) Advances of Lambatungnajökull generally occur during prolonged periods of negative NAO index. The main implication of this work relates to the exact timing of the Little Ice Age in the Northeast Atlantic. Mounting evidence now suggests that the period between AD 1750 and 1800, rather than the late 19th century, represented the culmination of the Little Ice Age in Iceland. 相似文献
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Marine pisolites from Upper Proterozoic carbonates of East Greenland and Spitsbergen 总被引:1,自引:0,他引:1
Upper Proterozoic carbonate successions from central East Greenland (the Limestone-Dolomite ‘Series’ of the Eleonore Bay Group) and Svalbard (the Backlundtoppen Formation of the Akademikerbreen Group, Spitsbergen, and the Upper Russö Formation of the Raoldtoppen Group, Nordaustlandet) contain thick sequences dominated by pisolites. These rocks were generated in shallow marine enviroments, and the pisoids are essentially oversized ooids. A marine environment is supported by the thickness and lateral extent of the carbonates; by a sedimentary association of pisolites with stromatolites, flake-conglomerates, calcarenites, calcilutites, microphytolites, and ooids similar to that found in numerous other Proterozoic carbonate successions; by sedimentary structures, including cross-beds and megaripples that characterize the pisolitic beds; and by microfossils of endolithic cyanobacteria that are specifically comparable to microorganisms that inhabit modern marine ooids of the Bahama Banks. Petrographic features and strontium abundances suggest that the pisoids were originally aragonitic, but neomorphism, silicification, calcitization, and dolomitization have extensively modified original mineralogies and fabrics. The East Greenland and Svalbard pisolitic carbonates reflect similar depositional environments and diagenetic histories, reinforcing previous bio-, litho-, and chemostratigraphic interpretations that the two sequences accumulated contiguously in a coastal zone of pisoid genesis which extended for at least 600, and probably 1000 or more, kilometres. 相似文献
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The role of the late Cimmerian unconformity for the distribution of kaolinite in the Gullfaks Field, northern North Sea 总被引:2,自引:0,他引:2
A study of the Middle Jurassic Rannoch Formation in the Gullfaks Field shows that there is no relationship between the content and distribution of kaolinite and location relative to the late Cimmerian unconformity. From petrographic data most of the kaolinite is interpreted to be detrital, and only traces of authigenic kaolinite are observed. Mass-balance calculations are used to provide guidelines as to the likelihood of kaolinite being formed and preserved in sandstones under the unconformity. The result of the calculations shows that the propagation rate of the dissolution front in the sandstones was probably on average slower than the erosion rates during the formation of the late Cimmerian unconformity. Hence, transformation of significant amounts of feldspar and mica to kaolinite probably did not take place within the sandstones which at present underlie the unconformity in the Gullfaks Field. Periods of exposure during formation of unconformities may thus be less effective causes of kaolinitization in sandstones than has been assumed. 相似文献
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Environmental impacts of the Norse settlement: palaeoenvironmental data from Myvatnssveit, northern Iceland 总被引:2,自引:0,他引:2
IAN T. LAWSON FREDERICK J. GATHORNE-HARDY MIKE J. CHURCH ANTHONY J. NEWTON KEVIN J. EDWARDS REW J. DUGMORE AARNI EINARSSON 《Boreas: An International Journal of Quaternary Research》2007,36(1):1-19
Lawson, I. T., Gathorne‐Hardy, F. J., Church, M. J., Newton, A. J., Edwards, K. J., Dugmore, A. J. & Einarsson, Á. 2007 (January): Environmental impacts of the Norse settlement: palaeoenvironmental data from Mývatnssveit, northern Iceland. Boreas, Vol. 36, pp. 1–19. Oslo. ISSN 0300–9483. The first stratigraphically continuous pollen profile spanning the Norse and Medieval periods from the archaeologically‐rich Mvatnssveit region of northern Iceland is presented. Detailed analyses were made of the tephra, sediment characteristics, pollen and chironomids of a 3 kyr sediment sequence from Helluvastjörn, a small, shallow lake. The pollen data show a steady decline in the percentage abundance of tree birch (Betula pubescens) pollen between the Norse settlement (landnám, c. AD 870) and c. AD 1300, a pattern that contrasts with the abrupt fall in birch pollen percentages immediately following the Norse colonization at almost all previously studied sites in Iceland. Some lines of evidence suggest that the gradual birch decline could be a result of reworking of soil pollen, but independent evidence suggests that this may not necessarily be the case. The pollen record indicates that birch woodland was replaced by acidophilic taxa (notably Empetrum nigrum and Sphagnum), again contrasting with the more usual pattern of Poaceae expansion seen in post‐landnám pollen diagrams from mires close to farm sites. Chironomid and Pediastrum accumulation data show that the limnic environment became more productive immediately after landnám, probably because of anthropogenic disturbance. An increase in sedimentation rate after landnám appears initially to have been caused by increased lake productivity, while reworked inorganic soil materials became a significant contributor to the sediments after c. AD 1200. The data suggest that the impact of settlement on terrestrial vegetation may have been more variable than previously thought, while freshwater ecosystems experienced significant and rapid change. 相似文献