Influence of harbour constructions on morphosedimentary changes in the Tinto-Odiel estuary mouth (south-west Spain)

The Odiel-Tinto estuary is one of the most significant estuarine systems along the mesotidal Huelva Coast. The dynamics of this coastal sector are controlled by the interaction of ebb-tidal currents and the prevailing southwesterly waves. The main sediment supply is provided by an intensive west-to-east longshore current, transporting sand from Portuguese cliffs and discharge from the River Guadiana. The tidal range is mesotidal (2.0 m) and the mean significant wave height is 0.6 m with an average period of 3.6 s. This estuary mouth comprises three different barriers separated by the main estuary channel, and another marginal one that drains a significant part of the system. Saltés Island can be found between these two channels, which is composed of sandy barriers separated by muddy salt marshes that form a protected natural park. East of the main channel is Mazagón Beach, one of the most important tourist resorts on this coast. Recent papers have demonstrated that Saltés Island evolved as a chenier plain over the last 3000 years. The cause of this evolution was a special wave refraction scheme caused by two ebb-tidal delta systems located at the end of the two tidal channels. Three important harbour infrastructures have been constructed at the estuary mouth: a) a jetty at the end of Saltés Island, finished in 1977; b) a second and shorter jetty bordering the marginal channel constructed in 1984, and; c) a dock for sailing activities built on Mazagón Beach. These three structures have modified the natural dynamic scheme. The first consequence was to inhibit the functioning of the chenier plain, affecting the natural environment; the second was to intensively erode Mazagón Beach, endangering this tourist site.This paper analyses the causal relationships that exist between the harbour infrastructures and the resultant modifications.     

Bedding-controlled coastal landslides in Southeast Britain between Axmouth and the Thames Estuary

The coastline of Southeast Britain is formed in sedimentary rocks of Jurassic, Cretaceous and Tertiary age, the majority of these deposits containing thick strata of mudrocks, which have very low angles of dip. Where these strata are appropriately exposed, particularly at the foot of a coastal slope, they give rise to landslides where all or part of the sliding surface follows a single bed of mudrock. Where the dip of the bedding is steep, such landslides are referred to as dip-slope failures. However, landslides where the basal sliding surface is controlled by the location and orientation of a single argillaceous bed in the sequence are better termed bedding-controlled landslides. In addition, where coastal slopes contain several layers of mudrocks, geometrically similar landslides may occur with perched slide surfaces breaking out at a higher level within the slopes. Landslides with strong bedding-controlled basal shear surfaces are the predominant form of instability along the southeast coastline of Britain. Many of the individual landslide cases used in this paper have been studied separately over many years. The general similarity of the different records is discussed, drawing important inferences on a number of aspects of these landslides with a variety of basal sliding surface geometries.     

The role of population change in widening the mortality gap in Scotland

The social gradient in health and mortality has been acknowledged for some time and, more recently, there is some evidence that the gap between the richer and poorer is widening in Britain. Other studies have also shown that health and mortality outcomes are worse in places that are experiencing population decline and better in places that are growing. This analysis examines, first, whether there is a mortality gap between the least and most deprived people in Scotland, second, whether this gap has widened since the 1980s and, third, whether the gap can be explained by patterns of population change. Our results demonstrate that the widening mortality gap in Scotland cannot be explained simply as an artefact of population change, even though it is widening most in those places that are experiencing population decline. This type of research is made possible by the reliable denominator population information provided in the 1981 and 2001 censuses.     

Stratigraphical and palynological appraisal of the Late Quaternary mangrove deposits of the west coast of India

The organic deposits derived from the mangrove swamps form reliable stratigraphic markers within the Late Quaternary sequence of Kerala–Konkan Basin. Three generations of such deposits have been identified. The older one is dated to around 43,000–40,000 ¹⁴C yr B.P., with a few dates beyond the range of radiocarbon. The younger ones date from the Middle Holocene to latest Pleistocene (10,760–4540 ¹⁴C yr B.P.) and the Late Holocene (<4000 ¹⁴C yr B.P.). Pollen analyses confirm that the deposits are mostly derived from the mangrove vegetation. Peat accumulation during the period 40,000–28,000 ¹⁴C yr B.P. can be correlated with the excess rainfall, 40–100% greater than modern values, of the Asian summer monsoon. The low occurrence of mangrove between 22,000 and 18,000 ¹⁴C yr B.P. can be attributed to the prevailing aridity and/or reduced precipitation associated worldwide with Last Glacial Maximum, because exposure surfaces and ferruginous layers are commonly found in intervals representing this period. The high rainfall of 11,000–4000 ¹⁴C yr B.P. is found to be the most significant as the mangrove reached an optimum growth around 11,000 ¹⁴C yr B.P. but with periods of punctuated weaker monsoons. From the present and previous studies, it has been observed that after about 5000 or 4000 ¹⁴C yr B.P., the monsoons became gradually reduced leading to drying up of many of the marginal marine mangrove ecosystems. A case study of Hadi profile provided an insight to the relevance of magnetic susceptibility (χ) to record the ecological shift in Late Holocene.     

The negative effect of environmental geological conditions of some geo-archaeological sites of North Coast and Alexandria

Three geo-archaeological sites at the North Coast and Alexandria, namely, the Alexandria wall (El Shalalat Park site), Abu Soir temple, and Marina excavations, were investigated to determine the negative impact of a salty environmental condition. The monuments suffer from rock decay of different rates. The geo-archaeological sites were built mainly from oolitic limestone blocks (i.e., the Alexandria wall at the El Shalalat Park site and Abu Soir temple) or excavated on them (i.e., Marina excavations). Field inspection and a lab analysis were carried out to understand the weathering mechanism. Salt weathering criteria such as disintegration, pitting, scaling, exfoliation, and honeycomb are observed on the Alexandria wall and upper parts of the Abu Soir temple, while dangerous cracks are detected on the Marina excavation tombs. The petrographic study of the oolitic limestone samples shows that they consist mainly of oolities and drusy sparite as a cement (oolitic grainstone). Some oolities have quartz grains as nuclei. Hydrochemical analysis shows that the total dissolved salts of extracted solutions of the North Coast quarry samples range from 539 to 686 ppm and dramatically increase (i.e., ten times) for extracted solutions from monument samples, ranging from 5395 to 6880 ppm. The dominant cation is sodium while the dominant anion is chlorine. Acid insoluble residue analysis shows that the carbonate content ranges from 89.2% to 96.4% for fresh samples from quarries and from 9.2% to 94.8% for weathered monument samples. The weight loss of the quarry oolitic limestone samples range from 30.7% to 32.7% and its physical and mechanical properties become worse after being subjected to 15 cycles of a durability simulation soundness test (using a sodium sulphate solution). Our main recommendations are to use suitable grouting for binding the cracks, high durability reconstruction rocks, and suitable cleaning methods to remove salts from the monuments.     

中国北部陆相侏罗系与英国海陆交互相侏罗系的对比研究——兼论中国北部侏罗系的划分与对比

通过中国北部陆相侏罗系与英国苏格兰西北部海、陆交互相大河口群叶肢介组合的对比和义县组底部与叶肢介共存的孔子鸟与德国索尔霍芬灰岩始祖鸟的对比,为中国北部陆相侏罗系与海相侏罗系的对应关系提供了三条对比等时线,并为陆相侏罗系的对比与时代提供了可靠的生物依据。     

华南沿海海平面的变化速率

应用回归分析和切比雪夫拟合二种方法，根据验潮资料研究了华南沿海海平面的变化速率，进而结合区域研究近２０年来华南海平面的变化特征，并讨论了将其用于地震趋势分析的可能性。     

Extensive deformations of rock slopes in southern Coast Mountains, southwest British Columbia, Canada

Extensive deformations of mountain slopes occur in crystalline intrusive rocks in the southern Coast Mountains of British Columbia. Typical morphological evidence of slope movement includes extensive systems of tension cracks, grabens, and antislope scarps (collectively referred to here as linears). These landforms involve displacements along penetrative joints observed in surface exposures. Kinematic tests on rock-structural data indicate that the observed patterns of linears are generally consistent with the feasible gravitational movements along the dominant discontinuities. Most sites indicate sliding as the most likely initial mode of movement, followed by or accompanied by toppling and toppling-induced sliding movements, and do not support the view that linears are the traces of active faults.     

Particulate metal speciation in surficial sediments from Loch Dee, southwest Scotland, U.K.

The geochemical partitioning of ten elements in stratified Holocene sediments from Loch Dee, southwest Scotland, has been established by use of a five-stage sequential extraction procedure. Samples from below 15 cm sediment depth show minimal evidence of modification by anthropogenic contamination or active diagenesis and hold Fe, Mg, Cu, Cd, Co, Pb, and Ni primarily in detrital silicates or organic complexes, while Mn, Ca, and Zn reside largely in adsorbed and reducible oxide phases. In the uppermost ca 15 cm of sediment, enhanced total concentrations of Zn, Cu, and Pb reflect increased atmospheric deposition during the postindustrial period. Of these metals, only Pb displays any notable adjustment of partitioning in the enriched zone, showing disproportionate accumulation in labile oxides and organic-Pb phases. The lack of Pb and Zn carbonates in the contaminated horizon may reflect inherent thermodynamic instability under the acid surface and pore-water conditions of Loch Dee. Increments to total Mn and Co in the surficial ca 5 cm of sediment are attributable to the accumulation of secondary oxides and adsorbed species, consistent with precipitation from the interstitial pore-waters across a sedimentary redox front. The presence of metals such as Zn and Cd in soluble or acid-volatile phases in the interfacial sediment has implications for the future management of the Loch Dee basin, with leaching into the overlying waters likely, given the continuation of current trends of lake acidification.