GPR studies over the tsunami affected Karaikal beach,Tamil Nadu,south India

In this study, results of GPR profiling related to mapping of subsurface sedimentary layers at tsunami affected Karaikal beach are presented . A 400 MHz antenna was used for profiling along 262 m stretch of transect from beach to backshore areas with penetration of about 2.0 m depth (50 ns two-way travel time). The velocity analysis was carried out to estimate the depth information along the GPR profile. Based on the significant changes in the reflection amplitude, three different zones are marked and the upper zone is noticed with less moisture compared to other two (saturated) zones. The water table is noticed to vary from 0.5 to 0.75 m depth (12–15 ns) as moving away from the coastline. Buried erosional surface is observed at 1.5 m depth (40–42 ns), which represents the limit up to which the extreme event acted upon. In other words, it is the depth to which the tsunami sediments have been piled up to about 1.5 m thickness. Three field test pits were made along the transect and sedimentary sequences were recorded. The sand layers, especially, heavy mineral layers, recorded in the test pits indicate a positive correlation with the amplitude and velocity changes in the GPR profile. Such interpretation seems to be difficult in the middle zone due to its water saturation condition. But it is fairly clear in the lower zone located just below the erosional surface where the strata is comparatively more compact. The inferences from the GPR profile thus provide a lucid insight to the subsurface sediment sequences of the tsunami sediments in the Karaikal beach.     

Internal structure of mixed-sand-and-gravel beach deposits revealed using ground-penetrating radar

ABSTRACT Mixed‐sand‐and‐gravel beaches are a distinctive type of coarse‐clastic beach. Ground‐penetrating radar (GPR) and photographic records of previous excavations are used to investigate the stratigraphy and internal sedimentary structure of mixed‐beach deposits at Aldeburgh in Suffolk, south‐east England. The principles of radar stratigraphy are used to describe and interpret migrated radar reflection profiles obtained from the study site. The application of radar stratigraphy allows the delineation of both bounding surfaces (radar surfaces) and the intervening beds or bed sets (radar facies). The deposits of the main backshore berm ridge consist of seaward‐dipping bounding surfaces that are gently onlapped by seaward‐dipping bed sets. Good correspondence is observed between a sequence of beach profiles, which record development of the berm ridge on the backshore, and the berm ridge's internal structure. The beach‐profile data also indicate that backshore berm ridges at Aldeburgh owe their origin to discrete depositional episodes related to storm‐wave activity. Beach‐ridge plain deposits at the study site consist of a complex, progradational sequence of foreshore, berm‐ridge, overtop and overwash deposits. Relict berm‐ridge deposits, separated by seaward‐dipping bounding surfaces, form the main depositional element beneath the beach‐ridge plain. However, the beach ridges themselves are formed predominantly of vertically stacked overtop/overwash units, which lie above the berm‐ridge deposits. Consequently, beach‐ridge development in this progradational, mixed‐beach setting must have occurred when conditions favoured overtopping and overwashing of the upper beachface. Interannual to decadal variations in wave climate, antecedent beach morphology, shoreline progradation rate and sea level are identified as the likely controlling factors in the development of such suitable conditions.     

Geophysical response of slackwater and sandy terrace deposits near Savanna, Northwestern Illinois

Low-permeability clayey and silty river terrace deposits are an important component in protecting underlying aquifers from contamination by agrochemicals and other contaminants. Such deposits also record deglaciation dynamics, meltwater drainage and local climatic variations. In this study, conducted over Mississippi River terraces near Savanna, Illinois, clayey slackwater terrace deposits and sandy terrace deposits are examined using resistivity soundings, ground-penetrating radar (GPR) profiles and direct-push conductivity logs. The clayey terrace deposits are characterized by low resistivity (10–35 ohm-m) and slow GPR wave velocity (0.07 m/ns), whereas non-clayey terrace deposits exhibit much higher resistivity (169–1,762 ohm-m) and faster GPR wave velocities (0.15 m/ns). Sandy and clayey terrace deposits may thus be differentiated and mapped on the basis of their geophysical response. Models based on resistivity soundings provide reasonably accurate estimates of the thickness of clayey slackwater deposits, but fail to reveal thin sands embedded in the clayey deposits. In some cases, the full thickness of the slackwater deposits was also not revealed. GPR profiles, however, imaged these embedded shallow sands and possibly imaged deeper sands below the base of the slackwater deposits, giving more accurate estimates of thickness. GPR also accurately resolved the thickness and character of sandy terrace deposits. Direct-push conductivity logs provide both accurate estimates of the thickness of clayey slackwater terrace deposits and a means of identifying thin embedded sands. In summary, resistivity soundings image these deposits at the lowest resolution with one-dimensional models, whereas GPR provides much higher resolution showing detailed layering within the upper several meters. Direct-push conductivity logs provide the highest resolution, but are invasive and only reveal stratigraphy at one location.     

Quantifying rates of coastal progradation from sediment volume using GPR and OSL: the Holocene fill of Guichen Bay, south-east South Australia

Guichen Bay on the south‐east coast of South Australia faces west towards the prevailing westerly winds of the Southern Ocean. The bay is backed by a 4 km wide Holocene beach‐ridge plain with more than 100 beach ridges. The morphology of the Guichen Bay strandplain complex shows changes in the width, length, height and orientation of beach ridges. A combination of geomorphological interpretation, shallow geophysics and existing geochronology is used to interpret the Holocene fill of Guichen Bay. Six sets of beach ridges are identified from the interpretation of orthorectified aerial photographs. The ridge sets are distinguished on the basis of beach‐ridge orientation and continuity. A 2·25 km ground‐penetrating radar (GPR) profile across the beach ridges reveals the sedimentary structures and stratigraphic units. The beach ridges visible in the surface topography are a succession of stabilized foredunes that overlie progradational foreshore and upper shoreface sediments. The beach progrades show multiple truncation surfaces interpreted as storm events. The GPR profile shows that there are many more erosion surfaces in the subsurface than beach ridges on the surface. The width and dip of preserved beach progrades imaged by GPR shows that the shoreface has steepened from around 2·9° to around 7·5°. The changes in beach slope are attributed to increasing wave energy associated with beach progradation into deeper water as Guichen Bay was infilled. At the same time, the thickness of the preserved beach progrades increases slightly as the beach prograded into deeper water. Using the surface area of the ridge sets measured from the orthophotography, and the average thickness of upper shoreface, foreshore and coastal dune sands interpreted from the GPR profile, the volume of Holocene sediments within three of the six sets of beach‐ridge accretion has been calculated. Combining optically stimulated luminescence (OSL) ages and volume calculations, rates of sediment accumulation for Ridge Sets 3, 4 and 5 have been estimated. Linear rates of beach‐ridge progradation appear to decrease in the mid‐Holocene. However, the rates of sediment accumulation calculated from beach volumes have remained remarkably consistent through the mid‐ to late Holocene. This suggests that sediment supply to the beach has been constant and that the decrease in the rate of progradation is due to increasing accommodation space as the beach progrades into deeper water. Changes in beach‐ridge morphology and orientation reflect environmental factors such as changes in wave climate and wind regime.     

Coastal changes along the coast of Vere, Jamaica over the past two hundred years: data from maps and air photographs

Analysis of air photographs and maps indicates complex patterns of shoreline changes along the south coast of Vere, Jamaica, between the mouths of the Rio Minho and Milk River. These include up to half a kilometre of shore-normal coastal recession between 1941 and 1991, the largest known shoreline change in Jamaica over the past 60 years. Previously, the coastline had been prograding seawards from a low cliff cut into the Rio Minho alluvial fan, in the process constructing a shore-parallel ridge and lagoon complex. The cliff itself is evidence of earlier coastal erosion. Maps published in 1804 and 1885 confirm the mobility of this coastline in historical times. They suggest that the more easterly complex of shore-parallel lagoons was constructed prior to about 1880, while the more recent, westerly beach ridges developed, at least partly, from progressive destruction of the lagoon complex, following a change in orientation of the Rio Minho mouth in the late 19th Century. Photographs of 1999 indicate the onset of accretion, probably resulting from the gradual onshore movement of massive quantities of sediment deposited off the Rio Minho mouth during the extreme flood event of 1986 and several lesser events in 1988 and the 1990s.     

烟台第一海水浴场沙源匮乏型海滩地貌和表层沉积物粒度特征

在烟台第一海水浴场,利用经纬仪进行2条海滩横剖面形态测量,并在不同地貌单元采集沉积物样品进行粒度分析。测量显示,该海滩仅有小规模沙坝和沟槽体系。后滨上有风成沉积,但滩肩和海岸沙丘发育均不明显。粒度分析结果表明,海滩沉积物以中砂、粗砂为主,杂以砾或细砂,比山东半岛其他海滩沉积物明显要粗。由陆向海沉积物呈带状分布,平均高潮线附近和沙坝迎水坡侵蚀作用均显著。因此认为缺乏沙源供应的基岩岬湾式海岸是导致沙滩地貌发育不典型、海滩侵蚀作用显著的主要原因。     

Gold in the beach placer sands of Chavakkad-Ponnani,Kerala Coast,India

Although sporadic mining of placer gold from river beds is not uncommon in India, there is no documented literature on the occurrence of gold in the beach placer sand deposits of the country. While characterizing the heavy minerals of the Chavakkad-Ponnani (CP) beach placer sands along the North Kerala coast, the association of gold with the pyriboles in these sands has been observed. A native gold grain of about 25 μm was seen to occur as an inclusion within an amphibole of hornblendic composition. The pyriboles of the CP deposit are angular to sub-angular indicating a nearby provenance that may be in the upstream reaches of the Ponnani River in the districts of Malappuram and Palakkad or further north in the auriferous tracts of the Wynad-Nilambur or Attapadi regions. It is argued that the occurrence of native gold in CP deposit is not a freak occurrence and that it warrants thorough investigation of all the pyribole-ilmenite-rich placers to examine the possible presence of gold and its abundance in the beach placers of northern Kerala coast.     

Large-scale structure of Calamus River deposits (Nebraska, USA) revealed using ground-penetrating radar

The large-scale (i.e. bar-scale) structure of channel deposits of the braided, low-sinuosity Calamus River, Nebraska, is described using ground-penetrating radar (GPR) profiles combined with vibracores. Basal erosion surfaces are generally overlain by medium-scale, trough-cross-stratified (sets 3–25 cm thick), very coarse to medium sands, that are associated with relatively high amplitude, discontinuous GPR reflectors. Overlying deposits are bioturbated, small-scale cross-stratified (sets <3 cm thick) and vegetation-rich, fine to very-fine sands, that are associated with low-amplitude discontinuous reflectors. Near-surface peat and turf have no associated GPR reflectors. In along-stream profiles through braid and point bars, most GPR reflectors dip downstream at up to 2° relative to the basal erosion surface, but some reflectors in the upstream parts of bars are parallel to the basal erosion surface or dip upstream. In cross-stream profiles through bars, GPR reflectors are either approximately parallel to bar surfaces or have low-angle inclinations (up to 6°) towards cut banks of adjacent curved channels. Basal erosion surfaces become deeper towards cut banks of curved channels. These structures can be explained by lateral and downstream growth of bars combined with vertical accretion. Convex upwards forms up to 0·5 m high, several metres across and tens of metres long represent episodic accretion of unit bars (scroll bars and bar heads). Stratal patterns in channel fills record a complicated history of erosion and deposition during filling, including migration of relatively small bars. A revised facies model for this type of sandy, braided river has been constructed based on this new information on large-scale bedding structure.     

Concealed thrusts in the Middle Gangetic plain,India – A ground penetrating radar study proves the truth against the geomorphic features supporting normal faulting

As no evidence for thrusting has yet been reported from the Indo-Gangetic plain so, the Himalayan Frontal Thrust (HFT) has been considered to be the southern most limit of the Siwaliks to the Indo-Gangetic plain. The present study highlights the thrusting activities between the Gandak and Kosi megafan area in the Middle Gangetic plain. As these thrust sheets are concealed beneath thick sediment cover, direct surficial studies of the discontinuity planes are not possible. Further, the topographic breaks formed by the backward erosion of the uplifted thrust faces resemble normal faults with hanging walls to south. Due to gradual decreasing upliftment and/or erosion from north to south, the area shows a step like topographic appearance. Ground penetrating radar (GPR) studies reveal the concealed thrust planes beneath the sediments and the topographic breaks looking like normal faults are interpreted to be the relief created by backward erosion of the thrust sheets along with the overlying sediments. Out of four GPR profiles taken using 100 MHz antennae, three are across the topographic breaks along which most of the terminal fans are formed and one across the basement fault to study its subsurface nature. Initially GPR failed to strike any subsurface discontinuities at the topographic breaks. However, at certain distance to the south of the topographic breaks, GPR was able to strike the northerly dipping subsurface discontinuity planes. By combining the seismological signatures (distribution of earthquake epicenters) with geomorphology, these discontinuities are identified as thrusts. The GPR profiles show a gradual decrease of dip of the thrust planes from north to south across the area. Hence, by the geomorphology, seismological behavior, topography, orientation and continuity, other topographic breaks can be compared with the proven thrusts. GPR study on the basement fault revealed that the NE–SW trending basement faults are not active in the area. The compression between the South Muzaffarpur fault and the peninsular shield led to the generation of the N–S trending extensional Hathauri–Simariaghat fault with downthrown block towards east. Due to depth penetration limit, the GPR study was confined within 15 m depth. The presence of the discontinuity planes up to the base of the GPR profiles indicate their continuity at least up to the base of Holocene sediments. Although this study brought out the presence of concealed thrusts to the south of the HFT, more detailed work is needed further to study their depth extension, relation to the basement and their implication in Himalayan tectonics in a broad manner. At present, we consider these thrusts to be the splays of the HFT. For confirmation, we propose to carryout detail seismic surveys in future research work.     

探地雷达(GPR)在海南岛东北部海岸带调查中的应用 *

对海南岛东北部海岸带调查采用了探地雷达(GPR)研究海岸带沙体的结构、展布和沉积序列,取得了很好的效果。文章通过和有限的露头资料对比以及对反射波形态、结构的研究,确定了海滩脊、海岸沙丘的反射特征以及潜水面的位置。雷达图像显示五龙港古海滩脊由亚水平、不连续、高振幅和透镜状反射波组成;木兰头海岸沙丘已受到人类活动的扰动,短的、陡倾斜反射可能代表未受扰动的海岸风成沙的前积层。研究表明探地雷达是一种可靠、快速和经济的地球物理方法,在砂砾质海岸可产生高质量、高分辨率和连续的反射剖面,值得加以推广。     

Application of GPR in the study of shallow subsurface sedimentary architecture of Modwa spit,Gulf of Kachchh

The coastline constitutes a very sensitive geomorphic domain constantly subjected to dynamic coastal processes. The study of its ever-changing physiography and stratigraphy provides a wealth of information on its history and evolution, in many cases at decadal and annual scales. The present study was carried out on the Modwa beach complex between Rawal Pir and Modwa, about 10 km east of Mandvi on the northern coast of the Gulf of Kachchh. The Modwa spit is a 7-km long WNW-ESE trending prograding amalgamated beach ridge complex that is about 0.5 km wide at its western end and 1.5 km wide at its eastern end. This Ground-Penetrating Radar (GPR) survey delineated a variety of the radar surfaces and radar facies which reflects not only large scale sedimentary architecture, but depositional facies of the beach ridge complex. These are bounding surfaces separating the radar facies outline beach ridge (br), washover (wo), coastal dune (cd) and swale (sw) depositional environments. The internal sedimentary structures like tangential, parallel, concave and convex upward stratifications could also be visualized from the GPR profiles. The architecture suggests the formation of this complex due to a combined process of eastward littoral drift of locally derived sediments and its onshore deposition by storms and eolian activities.     

Beach and nearshore morphodynamic changes of the Tabarka coast,Northwest of Tunisia

Aerial photographs taken in the 1963 and 2001 and bathymetric charts, in conjunction with coastal processes are analyzed to assess changes in rate of shoreline position, seabed level, and seabed grain sizes along the Tabarka–Berkoukech beach at the north-western Tunisian coastline. The littoral cell of this beach, 12-km-long, is bounded by pronounced embayments and rocky headlands separated by sandy stretches. Although not yet very much undeveloped, this littoral is still experienced degradation and modification, especially along its shoreline, with significant coastal erosion at some places. Results obtained from analysis of shoreline position indicate that El Morjene Beach is experienced a landward retreat of more than −62 m, at a maximum rate of −1.64 m/year, whereas the El corniche beach is advanced about 16–144 m, at an average rate of 0.42 m–3.78 m/year. This beach accretion has been formed on the updrift side of the Tabarka port constructed between 1966 and 1970. Comparison of bottom contours deduced from bathymetric charts surveyed in 1881 and 1996 off the coastline between Tabarka Port and El Morjene Beach identifies erosional areas (sediment source) and accretionary zones (sediment sink). Erosion (0.87–4.35 cm/year) occurs between El kebir River Mouth and El Morjene beach, whereas accretion exists in the zone down wind of the port ranges between 0.87 and 5.21 cm/year. Morphological analyses of the shoreline and the seabed of the study nearshore area indicate that shoreline retreat corresponds to areas of seabed scour (sediment source) while shoreline accretion is associated with areas of seabed deposition (sediment sink). Furthermore, simulation of wave propagation using STWAVE model combined with grain size distributions of the seabed shows that fine sands are much dominated in depositional areas with low wave energy, whereas coarser sands in erosive zones with high wave energy. The results obtained suggest that the change of seabed morphology, wave height pattern and grain size sediment have a great influence on the modification of shoreline morphology and dynamics.     

Ground-penetrating radar study of Pleistocene ice scours on a glaciolacustrine sequence boundary

Ice scouring of lake and sea-floor substrates by the keels of drifting ice masses is a common geological process in modern northern lakes and continental shelves, and was widespread during the Pleistocene. Nonetheless, the importance of scouring as a geological process is not yet matched by many sedimentological studies of scour structures exposed in outcrop. This article presents an integrated study combining outcrop sedimentology and subsurface ground-penetrating radar (GPR) data from a relict late Pleistocene ice-scoured glacial lake floor now preserved below beach sediments in Ontario, Canada. Scours occur along a regressive sequence boundary where deep-water muddy facies are abruptly overlain by shallow-water sands resulting from an abrupt drop in water levels. This has allowed the keels of drifting ice masses to scour into muds. Three-dimensional data gained from the GPR survey show that scours are as much as 2.5 m deep and 7 m wide; they have berms of displaced sediment and are oriented parallel to the former shoreline. Scoured shoreface sediments that fill scours show abundant liquefaction structures, indicating substrate dewatering during repeated scouring events similar to that recently reported in the modern Beaufort Sea in Canada's far north. Marked changes in water depths are typical of glacially influenced lakes and seas, creating opportunities for drifting ice to scour into offshore muddy cohesive facies and be preserved. The data presented here may aid identification in ancient successions elsewhere.     

Geophysical Surveys over Karst Recharge Features,Illinois,USA

Karst aquifers supply a significant fraction of the world's drinking water. These types of aquifers are alsohighly susceptible to pollution from the surface with recharge usually occurring through fractures and solution openings at the bedrock surface. Thickness of the protective soil cover, macropores and openings within the soil cover, and the nature of the weathered bedrock surface all influence infiltration. Recharge openings at the bedrock surface, however, are often covered by unconsolidated sediments, resulting in the inadvertent placement of landfills, unregulated dump sites, tailing piles, waste lagoons and septic systems over recharge zones. In these settings surface geophysical surveys, calibrated by a few soil cores, could be employed to identify these recharge openings, and qualitatively assess the protection afforded by the soil cover. In a test of this hypothesis, geophysical measurements accurately predicted the thickness of unconsolidated deposits overlying karstic dolomite at a site ab     

Theoretical and measured aeolian sand transport on a barrier island, Louisiana, USA

Over the past 100 years, the Isles Dernieres, a low lying barrier island chain along the coast of central Louisiana, Usa , has undergone more than 1 km of northward beach face retreat with the loss of 70% of its surface area. The erosion results from a long term relative sea level rise coupled with day to day wind and wave action that ultimately favours erosion over deposition. At a site in the central Isles Dernieres, 8 days of wind and beach profile measurements during the passage of one winter cold front documented aeolian erosion and deposition patterns under both onshore and offshore winds. For offshore winds, the theoretical erosion rate, based on wind shear velocity, closely matched the measured erosion rate; for onshore winds, the theoretical rate matched the measured rate only after being corrected by a factor that accounted for beach face morphology. In late February 1989, a strong cold front moved into coastal Louisiana. That cold front stalled over the Gulf of Mexico, resulting in 4 days of strong northerly winds at a study site on the Isles Dernieres. During those 4 days, the wind moved sand from the backshore to the upper beach face. When the cold front finally moved out of the area, the wind shifted to the south and decreased in strength. The onshore wind then restored some of the upper beach face sand to the backshore while increased wave activity moved the rest into the nearshore. The theoretical estimate of 1·28 m³ m^?1 for the rate of sand transport by the northerly wind compares well with the measured backshore erosion rate of 1·26 m³ m^?1, which was determined by comparing beach profiles from the start and end of the period of northerly winds. The theoretical estimate of 0·04 m³ m^?1 for the rate of sand transport by the southerly wind, however, is notably less than the measured rate of 0·45 m³ m^?1. The large discrepancy between the two rates can be explained by a difference in the shear velocity of the wind between the beach face, where the erosion occurred, and the backshore, where the wind stress was measured. Using an empirical relationship for the wind shear drag coefficient as a function of coastal environment, the theoretical estimate for the rate of sand transport by the southerly wind becomes 0·44 m³ m^?1     

Potential collapse of the upper slope and tsunami generation on the Great Barrier Reef margin, north-eastern Australia

Analysis of high-resolution multibeam bathymetry and seismic profiles in the Noggin Passage region, north-eastern Australia, has identified a small area (Noggin block) in the upper-slope offshore Cairns that may potentially collapse and generate a tsunami wave. The Noggin block extends from 340 to 470 m depth covering a roughly circular (2.4 km long and 3.7 km wide) area of about 5.3 km². The well-defined margins of the block correspond to different bounding seabed features. These features include steep headscarps, small landslides and a group of aligned circular pockforms up to 500 m wide and 20 m deep. Slope stability simulations indicate that the Noggin block is stable under normal present-day gravitational conditions on the upper slope. However, block failure may result under external loads, such as those produced by earthquakes. Failure modelling shows that critical peak horizontal accelerations of 0.2–0.4 g could lead to the collapse of the Noggin block. In north-eastern Australia, these acceleration values would involve earthquakes generated at short hypocentral distances and short periods. The collapse of the potential sediment slide mass of about 0.86 km³ (162 m average thickness) may lead to the formation of a landslide-generated tsunami wave. Semi-empirical equations indicate the collapse of this mass would yield a 7–11-m high three-dimensional tsunami wave. These waves could reach an estimated run-up height at the coast of 5–7 m. Our first-order approach highlights the potential consequences for nearby coastal communities, the need for better sediment characterisation in the study area, and the systematic identification of other areas prone to slope failures along the Great Barrier Reef margin.     

Imaging fracture distributions of the Al-Khuff Formation outcrops using GPR and ERT geophysical techniques,Al-Qassim area,Saudi Arabia

Khuff Formation is of utmost importance in Saudi Arabia for oil and gas reservoir although it is composed mainly of limestone. This reason refers to the existence of intensive fractures which play a vital role in the increase in porosity and permeability of this formation. The fracture pattern in the study area was verified through 2D and 3D ground penetrating radar (GPR)-defined and electrical resistivity tomography (ERT)-defined surveys. In this respect, ten of 2D GPR surveys were collected along an intersected grid of profiles covering the study area while ERT data were collected along three profiles of the GPR grid. The results were interpreted in light of the field-based structural and stratigraphic assessment of the outcropping rocks. The analysis of the inverted ERT and filtered GPR sections revealed the presence of fractures. Several resistivity and electromagnetic reflection anomalies were laterally and vertically identified across the measured sections clarifying fractures that extend to a depth of 24 m in the limestone. Most fractures are oriented vertical to sub-vertical dipping both east-west and north-south.     

Sedimentary evidence and luminescence and ESR dating of Early Pleistocene high lake levels of Megalake Tengger,northwestern China

The timing of high lake-level stands during the Late Pleistocene in western China remains controversial. Here we report new results from Megalake Tengger based on a study of palaeo-shorelines and a drill core from Baijian Lake in the northwestern Tengger Desert. Multiple dating methods, based on luminescence signals (quartz optically stimulated luminescence, K-feldspar post infrared-infrared stimulated luminescence) and electron spin resonance signals of quartz, were used to date beach sands from palaeo-shoreline profiles at altitudes of ~1310 m (+20 m above lake level), ~1320 m (+30 m) and ~1350 m (+60 m), and from the top 20 m of sandy sediments from the drill core obtained from the modern beach of Baijian Lake. The dating results show that high lake-level stands associated with the previously reported Megalake Tengger (~1310–1320 m) occurred during the late Early to Middle Pleistocene, which is much earlier than previously reported. In addition, no geomorphological evidence of shorelines and sedimentary evidence from the drill core profile were found to support the previously reported Late Pleistocene lake levels. Our results indicate that the exact age of the previously reported ‘high lake level event’ in a large part of northwestern China during the Late Pleistocene needs to be re-evaluated.     

Heavy Minerals Concentration in the Beach Sands of the Uae Northern Coastline

The northern section of the UAE is bordered by the Gulf of Oman’s northern extension (East Coast) and Arabian Gulf’s Eastern extension (northern West Coast). Unlike the rest, the coastline of this section is more or less faced by mountainous areas of various rock types. The beach sands a long this coastline at both sides (East and northern-West) signify some heavy minerals concentration of an important consideration.