Correlation of the Kimmeridgian-Tithonian (Jurassic) boundary beds exposed in the Boulonnais,France with those at Kimmeridge,Dorset, UK

Sediments of Kimmeridgian and Tithonian age are well exposed on the Boulonnais coast of northern France between Equihen and Cap Gris Nez and on the south coast of England at and adjacent to Kimmeridge Bay. Both successions were deposited on a marine shelf and lie within the Subboreal faunal province which enables detailed correlations to be made between them based on ammonite assemblages. They are, however, lithologically markedly different due to their environmental settings: close to a land area in the case of the Boulonnais and within a depositional basin in the case of Kimmeridge. The succession adjacent to the Kimmeridgian-Tithonian boundary exposed in the Boulonnais is highly condensed and laterally variable with more attenuated successions occurring close to the former Anglo-Brabant Massif land area. The boundary occurs at the end of a succession of up to six regressive-transgressive events that onlap the land area. This is in contrast to that at outcrop at Kimmeridge, where the Kimmeridgian-Tithonian boundary is marked by a correlative conformity in an unbroken basinal succession. The cliff and foreshore exposures in the Kimmeridge area provide the only unbroken succession in the Subboreal faunal province of the beds adjacent to the Kimmeridgian-Tithonian boundary.     

A Post K-T Boundary (Early Palaeocene) Age for Deccan-type Feeder Dykes, Goa, India

Basaltic dykes exposed along the coast of Goa represent theyoungest phase of a number of different mafic suites intrudingthe complex Precambrian terrain that forms the pre-Deccan basementof peninsular India. These dykes crop out     

A geological excursion in the Wadi Fatima area, near Jiddah, Saudi Arabia

Wadi Fatima, east of jiddah on the Red Sea coast of Saudi Arabia, is a microcosm of the geology of the jiddah area. Rocks ranging in age from 800-million-year-old metamorphic rocks to Tertiary lava flows are exposed, and illustrate the geological richness of western Saudi Arabia. The valley is a major south-west-trending fault zone that has been active since Precambrian times. A major Tertiary dyke swarm in the vicinity of Wadi Fatima is related to the opening of the Red Sea as the African-Arabian landmass split apart.     

Recent dynamics of subarctic dunes as determined by tree-ring analysis of white spruce, Hudson Bay, Québec

The radial-growth patterns of white spruce were studied on a number of trees growing in subarctic dunes along the eastern coast of Hudson Bay to calculate the rates of accumulation, erosion, and migration of cold-climate sand dunes. The average rate of sand accumulation in sheltered dunes (forest sites) was 2.5 to 3.3 cm/yr, which is two to three times lower than in highly exposed dunes with a rate of sedimentation of 7.65 cm/yr. The average erosion rate was 1.4–1.7 cm/yr, about two times lower than the accumulation rate. The migration rate of sheltered dunes was 18 to 30 cm/yr, three to five times lower than for an exposed dune which advanced at a speed of 74 cm/yr. This migration rate established for highly exposed dunes in the Subarctic with tree-ring methods is about 10 times lower than that established for a barchan in the Sahara with other methods.     

Geomorphology of the eastern coast of the Dead Sea, Jordan

This paper aims to investigate the geomorphological characteristics of theeastern coast of the Dead Sea as influenced by structural instability andclimatic changes. Aerial photos and map analyses served to distinguish mainmorphological features and slope classes, whereas geomorphological changesalong the cost, mainly those developed by the declining of the Dead Sealevels were located and examined in the field. The eastern coast of the DeadSea was considered an ultimate outcome of stream work practiced undercontrols of sea-level lowerings. Climatic, hydrological and structuralinstabilities characterizing the study coast put watersheds and wadisdraining into the sea under accelerated erosion that produced huge volumes ofsediments to be deposited in the upper levels of the subsiding former lakesof the Dead Sea. Retrogradation exposed subaqueous deltaic-fluviatileformations, contributing to coastal geomorphological development. Also,present climatic seasonal fluctuations, rejuvenating stream work, continue tosubject past depositional environments to denudation as the stream distanceof transport is increased, and newer subaqueous deltas are being formed.Weathering and mass-wasting processes added to such a development byenhancing the formation of karst, tofoni and pedestal features as well as thehigh erodibility rate of deltaic sediments which endagers constructionalprojects along the study coast.     

The Lower Jurassic of the Eastern Caspian region and the Middle Caspian Basin: Lithology,facies, taphonomy

Lithofacies of the productive Upper Triassic-Lower Jurassic deposits of the Eastern Caspian region, studied in wells on the Caspian coast and exposed in the outcrops of the Mountainous Mangyshlak, are described and analyzed. The similarity of the structure of the Mesozoic sedimentary beds of the Middle Caspian Basin and of those of the land adjacent to its eastern coast is confirmed. Comparative analysis of lithofacies allowed the reconstruction of the paleogeographic setting and depositional environments in the studied region during the Early Jurassic. A unique fossil plant occurrence is discovered in the upper part of the Lower Jurassic series (in the lower subformation of the Kokala Formation; Eastern Caspian region). Fossil plant taphonomy and the lithology of host rocks in the occurrence resulted from unusual paleogeographic settings that existed in the Middle Caspian Basin at the time of the Early-Middle Jurassic boundary.     

柯坪露头区早志留世三角洲及碎屑海岸沉积

塔里木盆地阿克苏市柯坪露头区下志留统地层出露连续、完整,是较好的海相碎屑岩沉积露头研究区,其沉积体系类型有待进一步探讨。笔者通过多次精细的露头沉积学观察及室内研究,对柯坪露头区下志留统海相碎屑岩沉积体系类型及其特征进行了分析研究。识别出三角洲及碎屑海岸沉积(潮坪),并在该区提出了河流作用为主的三角洲和潮汐影响三角洲两种三角洲类型。柯坪塔格组主要为河流作用为主的三角洲沉积,而塔塔埃尔塔格组则主要发育潮汐影响三角洲及潮坪沉积。探讨和对比了各类型沉积体系的沉积特征及其之间的差异性。     

A rapid rise in relative sea level ~9–7 cal ka bp along the SW Cumbria coast,NW England

Along the macro-tidal (10.7 m tide range) SW Cumbria coast in situ rooted tree stumps are infrequently exposed below present-day low Spring Tide elevations (≤−4.5 m OD). To date these remnants, we conducted a salvage operation at two sites on in situ rooted tree stumps exposed below the lowest tide levels; these sites are no longer exposed. We obtained four radiocarbon dates on these tree remnants and reference an earlier site recovered in 1972. One wood sample was identified as Quercus robur or Q. petraea, while samples from Haverigg and Kirby-in-Furness are tree Salix spp. The median group age for the rising relative sea level (RSL) that killed the trees was 8602 ± 243 bp cal a bp with an estimated Mean Tide Level (MTL) of ~≤−9 m. Evidence indicates that RSL rose ~10 m along this section of coast at a rate of between of between 18.5 and 8.7 mm a^–1 until ~6800 cal a bp , or earlier, before the rate of global sea level rise fell below that of the local glacial isostatic recovery. The transgression is coeval with rapid collapse and deglaciation of the Laurentide Ice Sheet in Hudson's Bay and slightly lags the global Meltwater Pulse-1C.     

Sedimentary variations of geomorphic subenvironments at Al-Lith area,central-west coast of Saudi Arabia,Red Sea

Sediment characteristics are the indicators of the intensity and geological history of the processes active in an area. Their association with different geomorphic features also signifies the present day conditions of deposition. In this study, variations in sediment characteristics associated with different geomorphic features, such as the coastal zone, two islands and a lagoon in the Al-Lith area of central-west coast of Saudi Arabia have been analysed. Whereas, the detrital sediments (sand?+?mud) are common (61–87 %) in most of the subunits of the coastal zone; the nondetrital (carbonate rich) sediments are more common (54–95 %) on the two islands as well as the lagoon; indicating distinct sources of sediments in these regions. The variation of sediment texture between sand and sandy silt in most geomorphic units, also shows that they are exposed to high-energy conditions, whereas occurrence of heavy minerals in small proportions (<7 %) indicates limited inputs from land-based igneous and metamorphic rocks. Sediment mean size vs. standard deviation shows that the sediment characteristics of a geomorphic unit (e.g. beach or sand bar) on the coast and on the island are different owing to different processes responsible for their formation.     

Application of wave transformation models for estimation of morphological changes at Vellar estuary,southeast coast of India

Assessment of the wave climate at near coast is vital for estimation of morphological changes, such as growth of sand spit and associated siltation of tidal inlets. Vellar (bar-built) estuary is one of the prominent estuaries along the southeast coast of India, located at 11°30′N and 79°46′E, less studied in terms of its morphological features. The inlet of Vellar is exposed to high energetic waves, inducing large sediment transport rates and shoreline changes. Local wave characteristics are not accurately defined and the available wave information at near coast is limited (point based observations). In the present study, three decoupled numerical models are employed to derive the monthly nearshore wave climate at Vellar by transforming waves from deep water to nearshore. These models are independently validated with buoy observations in deep water and wave gauge data at nearshore. Based on the nearshore wave data, littoral drift along the coast was estimated and compared with the spit growth at Vellar inlet. The estimated average littoral drift along this coast from February to October is 1.93 × 10⁶ m³ toward north and from November to January it is 1.52 × 10⁶ m³ toward south, resulting in a net northerly drift. Results indicated that increase in the wave energy during the period of July to September is responsible for the maximum growth of the sand spit observed in the field.     

Distribution of coastal cliffs in Kerala,India: their mechanisms of failure and related human engineering response

The 560-km-long Kerala coast is characterised by long barriers with narrow beaches and steep cliffs. Distribution of cliffs from nine sections measuring a cumulative length of 63.5 km is evaluated in ArcGIS Software using topomaps and field survey data. The cliff sections in the southern coast comprise both permeable and impermeable rocks, whereas those along northern coast are comprised of either Precambrian crystalline and/or Tertiary formations. Notches, caves and even small arches are developed in Cannanore, Dharmadam and Kadalundi cliffs, where only primary laterites are exposed to wave attack. Stacks composed of laterite and Precambrian crystallines found in nearshore of cliffed coast indicate recession of shoreline. Mass wasting, mudslide and mudflow type of cliff failures are common in permeable to semi-permeable rocks, whereas rotational sliding, rockfall and toppling failure are found in hard rock cliffs. Retreat of cliff sections are induced by natural or anthropogenic activities or both. Rate of recession vary from a few centimetres to one metre/year depending upon the nature of lithology, structures and recession agents acting upon the cliffs. Various methods of cliff protection for e.g. hard structures—revetments, groins, seawalls, breakwater and jetties—and soft measures—artificial reefs/marsh creation, floating breakwaters, beach nourishment, beach scraping and vegetation planting—are suggested.     

Stratigraphy of the upper Jurassic-lower cretaceous Nordenskjöld Formation of eastern Graham Land, Antarctica

The Nordenskjöld Formation is a sequence of thinly interbedded ash beds and black, radiolarian-rich mudstones which is exposed on the eastern coast of the Antarctic Peninsula. As a result of recent field work, the Nordenskjöld Formation has been re-examined and redefined with three new members recognized — the Longing, Ameghino, and Larsen members. The age of the formation, based on its macrofossil content, is Kimmeridgian to Berriasian, although reworked clasts from James Ross Island suggest it might range down into the Oxfordian.     

The Saline Lakes of the McMurdo Dry Valleys, Antarctica

The McMurdo Dry Valleys of Antarctica are among a rare group of ice-free regions lying along the coast of an otherwise ice-burdened continent. For Antarctica, these are highly atypical regions of exposed rock and barren soils. Within their 4,000 km² expanse, the valleys contain a number of permanently ice-covered, closed-basin lakes, which range from freshwater to highly saline environments. This paper examines the physical structure, geochemistry, nutrient and trace metal dynamics, biology, and hydrologic history of saline Lake Bonney (both east and west lobes), Fryxell, Vanda, and Joyce and provides an update to recently published volumes on these pristine systems.     

Modeling of inundation dynamics on Banda Aceh,Indonesia during the great Sumatra tsunamis December 26, 2004

The tsunami inundation flows on Banda Aceh, Indonesia reached 5 km inland during the December 26, 2004, event and devastated most of the houses, buildings, and infrastructure along the coast and killed more than 167,000 people. The overland flows from the northwest coast and the west coast collided at Lampisang village approximately 3.7 km from Ulee Lheue (northwest coast) and 6.8 km from Lhok Nga (west coast) as reported by survivors. Inundation modeling based on the nonlinear shallow-water wave equations reproduces the inundation pattern and demonstrates a colliding of the overland flows. The model suggests that wave characteristics on the northwest coast of Banda Aceh were different from those on the waves that impacted upon the west coast. The areas, which experienced higher inundation levels, did not always experience greatest overland flow speeds, and the damage areas mostly coincide with the flow speed distribution rather than the runup and inundation depth.     

Beachrock as evidence of sea-level lowstand during the classical period,Parion antique city,Marmara Sea,Turkey

Results obtained from beachrock lying on the north coast of the antique city of Parion in Çanakkale province, NW Turkey, are presented based on field data, petrographic analyses, cement fabrics, and radiocarbon dating. Extending to 20?m offshore at a depth of ?2?m, the studied 50-cm thick beachrock is poorly sorted lithic sandstone. Both exposed and submerged parts are characterized by sequentially precipitated marine phreatic and vadose cements composed of micrite encrustations with micro-organism borings, pseudopeloidal aggregates of high-Mg calcites with scalenohedral habits and meniscus bridges. Radiocarbon ages point to a deposition during the classical period when the sea level was below (between ?1 and ?1.5?m) that of the present. The beachrock witnesses a granule- and pebble-dominated wide beach prior to cementation, suggesting that Parion’s fortification walls were behind the coastline during this lowstand and raises questions concerning the existence of a harbor north of the city.     

Exploring for heavy minerals on Cape York Peninsula,Queensland, Australia

This paper describes the results of a preliminary study of the heavy mineral (HM) potential of the northwest coast of Cape York Peninsula in far north Queensland that was funded by the Queensland Government's Future Resources Program Industry Priorities Initiative. The study found that the northwest coast may have the potential to host world-class HM deposits. All the essential ingredients in a HM mineral system are present: fertile source rocks, effective transport mechanisms and abundant potential trap sites, particularly along the well-preserved Pleistocene coast.

The source rocks are Proterozoic metamorphic and Paleozoic granitic rocks of the Coen Inlier and Mesozoic sedimentary rocks of the Laura and Carpentaria basins, all of which crop out along the spine of the Peninsula. These rocks were exposed in the early Cenozoic and were vigorously eroded by seasonally active rivers throughout the Quaternary. Most of these rivers are currently carrying HM, and the zircon content in river sediments in the region is comparatively high. It is speculated that in the late Pleistocene HM delivered by rivers to the northwest coast were transported predominantly in a southwesterly direction, and trapped in the swash zone of prograding beaches. It is further speculated that at this time the coastline was deeply embayed with cliffs and headlands formed in bauxite, and that structural trap sites formed on the northeastern side of prominent headlands.

Pleistocene coastal sediments were partially reworked by Holocene coastal processes, and HM liberated by these processes may have been captured by prograding Holocene beach ridges. These Holocene beach ridges are not as extensive as the Pleistocene beach ridges but are more prominent, partly because they are less well vegetated. The Holocene coastline was probably more regular than the Pleistocene coastline, with fewer headlands to create structural traps. The modern coastline is relatively starved of river sediment because the Holocene and Pleistocene coastal sediments act as barriers to river flow.

It is recommended that ongoing exploration for HM in the region should focus on potential trap sites on the Pleistocene coast and that two sites, Vrilya Point and Jackson River, where structural traps may have been formed by coastal promontories, should be priority targets. It is also noted that if the exploration of Cape York Peninsula for HM deposits is to be effective, further research needs to be carried out into the geomorphological evolution of the west coast and, in particular, the role of cyclones in forming HM deposits in tropical climates.     

Chronology of upper Quaternary offshore successions from the southeastern Mediterranean Sea,Israel

Pleistocene and Holocene transgressions advancing over the shelf that was exposed during glacial maxima drowned any continental and shallow marine sediments deposited during low sea level stands. To complement records from sequences exposed on land, core material from the shallow continental shelf is needed to reconstruct climatic and sea level fluctuations. Two cores drilled offshore Ashqelon off the southern Mediterranean coast of Israel, in a water depth of 10 and 25 m, were analyzed. Sedimentary facies and faunal analyses indicate that most of the sediments were deposited in nearshore environments, with only short intervals of continental episodes. Luminescence dating of alkali feldspar and quartz, as well as ¹⁴C ages of mollusks, date the cores to marine oxygen isotopic stages 6–1, between ∼140 and 5 ka. Comparison between the dating methods shows that most alkali feldspar ages agree with independent sea level and sedimentological constraints while quartz ages are overestimated.     

Early Weichselian palaeoenvironments reconstructed from a mega-scale thrust-fault complex, Kanin Peninsula, northwestern Russia

A section, almost 20 km long and up to 80 m high, through alternating layers of diamict and sorted sediments is superbly exposed on the north coast of the Kanin Peninsula, northwestern Russia. The diamicts represent multiple glacial advances by the Barents Sea and the Kara Sea ice sheets during the Weichselian. The diamicts and stratigraphically older lacustrine, fluvial and shallow marine sediments have been thrust as nappes by the Barents Sea and Kara Sea ice sheets. Based on stratigraphic position, OSL dating, sea level information and pollen, it is evident that the sorted sediments were deposited in the Late Eemian-Early Weichselian. Sedimentation started in lake basins and continued in shallow marine embayments when the lakes opened to the sea. The observed transition from lacustrine to shallow marine sedimentation could represent coastal retreat during stable or rising sea level.     

How has coastal erosion affected the prehistoric settlement pattern of the boothbay region of maine?

Erosion of complex, rocky coasts has largely been neglected by geologists. Thus, a geo-archaeological study of coastal erosion was required before analysis of the prehistoric settlement pattern could be undertaken. Along the outer, wave-dominated coast of Maine, erosion is episodic, occurring when large storms raise water levels to new heights. Along the inner, tide-dominated coast, erosion occurs more frequently because unconsolidated sediments are exposed at low elevations in bedrock features. The shell midden archaeological sites of the Boothbay, Maine region are situated in the most rapidly eroding areas; therefore, it can be reasoned that localities without cultural deposits were never occupied. On the other hand, coastal erosion is widespread enough to insure that sites have been exposed to discovery by archaeological survey. Settlement pattern analysis of the study area is, therefore, not biased by differential preservation or discovery of archaeological sites.     

Sodium,magnesium, potassium and calcium concentrations in ice cores from the Law Dome,Antarctica

The concentrations of Na, Mg, K and Ca have been determined in three ice cores drilled along a flow line on the Law Dome, Antarctica. Average cationic concentrations in the upper sections of the cores show a marked decrease in concentration with increasing distance from the coast. A depth profile of the core drilled 5 km from the coast near Cape Folger indicates that the ice below 260 m was precipitated in a colder climate regime, probably towards the end of the Wisconsin stage. The depth profile of the core located at the summit of the dome, 110 km from the coast, shows an unexpected steady increase in the concentration of cations with depth. This may indicate an increase in precipitation, or a gradual change in wind patterns on the dome over recent centuries.