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31.
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Parallel to the Essex coast north of the mouth of the Thames, a series of gravel spreads ranging in altitude from near sea level westward to more than 200 ft O.D. (mean sea level) proved to be the remnants of an abandoned Thames/Medway terrace system, rather than a series of “raised” beaches, as their location had suggested. The seaward side of the ancient river valley has subsequently been “captured” by subsidence.Evidence is given for five terraces, with surface levels between 5 and 75 ft O.D. Because of subsidence of the Essex coast, the terrace levels are not easily correlatable with either the Thames or Medway terrace levels. Temporal placement is attempted on the basis of one site in the 25 ft Barling terrace, which yielded a Middle Acheulian archaeological assemblage associated with a cool temperate fauna including an early form of mammoth. An ice wedge cast in the Barling terrace was filled with floodloam which weathered to a parabraunerde soil during an interglacial climate warmer than now. For these reasons man is thought to have lived on the floodplain of the Barling terrace either at the onset of the Wolstonian (Riss) glacial or during an interstadial of that stage. The question of possible linkages between Swanscombe and Clacton terraces is discussed. 相似文献
33.
Scott?W.?NixonEmail author Stephen?Granger Betty?A.?Buckley Melissa?Lamont Brenda?Rowell 《Estuaries and Coasts》2004,27(3):397-404
We have compiled what we believe is the longest coherent coastal sea surface temperature record in North America. Near-surface water temperature measurements have been made almost daily at Great Harbon, Woods Hole, Massachusetts, since 1886 with remarkably few gaps. The record shows that there was no significant trend in water temperature at this site for the first 60 yr of observation. There was some cooling during the 1960s that was followed by a significant warming from 1970–2002 at a rate of 0.04°C yr?1. During the 1990s annual mean temperatures averaged approximately 1.2°C warmer than they had been on average between 1890 and 1970; winter (December, January, and February) temperatures were 1.7°C warmer and summer (June, July, and August) temperatures were 1.0°C warmer. There has not been a statistically significant decrease in the annual number of winter days below 1°C or an increase in the annual number of winter days above 5°C. The number of summer days each year with water temperature above 21°C has not increased significantly. The dates of first observations of 10°C and 20°C water in the spring have not changed sufficiently to be statistically significant. There is a weak positive correlation between annual and winter water temperature and the annual and winter North Atlantic Oscillation index, respectively, during the period of record. 相似文献
34.
Birchenough AC Barnes N Evans SM Hinz H Krönke I Moss C 《Marine pollution bulletin》2002,44(6):534-543
It is evident from measures of butyltin tissue burdens and imposex or intersex in neogastropods that tributyltin (TBT) contamination of coastal waters and open parts of the North Sea is now low. It has been declining for at least the past decade. This is probably due to two measures. First, regulations prohibiting the use of TBT-based paints on small boats and fish farms have reduced inputs of TBT from these sources so that they are now negligible (except possibly where the regulations are flaunted). Second, there is evidence from sites, where commercial vessels are the sole source of TBT, that the adoption of TBT SPC paints has been effective in reducing environmental levels of these contaminants. However, poor dockyard practices, allowing TBT-contaminated wastes, including paint flakes, to accumulate in sediments have left a legacy of hot-spots of contamination in some ports. The impact is localised so that TBT contamination is low in coastal areas immediately adjacent to ports. 相似文献
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Moses Karakouzian B. Bur in Avar Nick Hudyma Jeffrey A. Moss 《Engineering Geology》2003,67(3-4):233-242
This paper presents the observations of cone penetration testing (CPT), in situ vane shear testing and undrained triaxial testing of underconsolidated marine clay in the Craney Island Dredged Material Management Area (CIDMMA), Norfolk, VA. Comparison of vane shear measurements, taken during 1981–1983, to CPT measurements, taken during 1993, indicates a change in undrained shear strength. Both the vane shear and cone penetration resistances are lowest at the mid-heights of the clay layers and the excess pore water pressures are highest at the mid-height of the clay layers, indicating that the clay layer is underconsolidated. 相似文献
37.
Biological diversity, or biodiversity, is high on the international agenda for nature conservation. Marine and coastal ecosystems account for an important share of the biological diversity on Earth. As a consequence many international conventions, European legislation and national laws refer to marine biodiversity. The protection of marine biodiversity is a complex legal issue as it requires consideration of geographic (between land and sea), political (between conservation and exploitation), and economic (between fisheries, tourism, intellectual property and many other sectors) factors. Like Matryoshka dolls, marine biodiversity is a heterogeneous notion difficult to address as one discrete area in the development of policy agendas or juridical frameworks. In the past decade, the EU has been very active in Promoting Integrated Coastal Zone Management and in developing a framework for an Integrated Maritime Policy. This article reviews the status of marine biodiversity in the policy and legal initiatives of the European Union, a challenging issue to both the objectives of conservation and to the concept of integration. 相似文献
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39.
There is a generally accepted assumption that the primary productivity of the natural vegetation cover of an area is the most appropriate indicator of the level of primary productivity that may be attained by agricultural systems in the same area. However, this relationship is not clearly understood. This paper assesses the potential rate of primary productivity for southern Ontario and compares these results with the equivalent values for the agro-ecosystems. Analysis is conducted at the level of the county. Climatically determined potential (natural) primary productivity values are adjusted by a soil performance index yielding a range of values from 986 g m?2 y?1 to 44 g m?2 y?1. The actual primary productivity for agriculture ranges from 3593 g m?2 y?1 to 515 g m?2 y?1. Over southern Ontario actual (agricultural) productivity exceeds potential (natural) productivity by an average of 2.6. The variations about this mean are examined. The results indicate where, and by which agricultural processes, the humanized landscape can improve the organic resource base. 相似文献
40.
David Moss 《Astrophysics and Space Science》1984,104(2):253-258
Calculation similar to those of Mestel and Moss (1983) are performed to investigate the decay of a toroidal field through configurations satisfying the torque free condition, imposed by the presence of a poloidal field of dipolar form confined beneath the solar convection zone. It is found that initially stable field configurations diffuse into unstable configurations on time-scales of order a few x 108 yr. The results are similar to those of Tayler (1982) for a simpler field model without any dynamical constraints. 相似文献