shear in the lower crust during extension not so pure and simple abstract as lower crustal reflectivity appears to be related to extension it is sensible to consider the role of the lower crust in the extension of the lithosphere and in particular the way the lower crust deforms the occurrence of transparent zones wrapped around by reflective bands can be interpreted as low strain regions enclosed within anastomosing shear zones suggesting that deformation in the lower crust is by the relative movements of low strain lozenges along acoustically reflective high strain zones although this deformation can easily accommodate bulk pure shear it can also develop during bulk simple shear a component of subhorizontal simple shear within the lower crust is necessary if deformation in the mantle is localised into shear zones with the geometry and distribution imaged on birps profiles the lower crust may be the critical link in the lithosphere transferring deformation between the relatively strong upper crust and upper mantle and being strongly sheared in the process the form of this shearing is a direct consequence of the way the entire lithosphere extends

following the last neanderthals mammal tracks in late pleistocene coastal dunes of gibraltar s iberian peninsula abstract the aeolian pleistocene deposits recorded in the rock of gibraltar s iberian peninsula present a significant sedimentary thickness that fills the wide sea caves and covers its steep slopes in catalan bay these deposits register the development of cliff foot and rampant dunes that form a 35 sand ramp 1 km long and up to 300 m in height formed by moderately to well sorted sands slightly carbonated and weakly cemented this morphosedimentary evidence is associated with mis 5 2 sea level fluctuations its internal structure shows lamination sets of 2 3 m in thickness and planar and trough cross bedding in these beds five morphotypes of mammalian footprints have been recognized in vertical cross sections and convex hyporeliefs most of them present a moderate degree of conservation due to the poor cementation of the sands these icnites are related to the activity of terrestrial mammals possibly belonging to homininae proboscidea artiodactila and carnivora the affinity between the footprints and their tracemakers has been established in the basis of their physical parameters the shape of the footprints their comparison with similar footprints and the correlation with the fossil fauna of vertebrates described for the late pleistocene in gibraltar these findings represent the first palaeoichnological record in the aeolian sediments of gibraltar and indirectly corroborate the occupation of the coastal dune landscape by several terrestrial mammals during the late pleistocene in addition they help reconstructing the animal behaviour and interaction with the extensive dune systems that developed at the foot of the rock slopes the age of the tracks has been established within the mis 2 during the probable middle upper palaeolithic transition in the climate refuge of gibraltar

quantitative analysis of temporal variations on shoreline change pattern along ganjam district odisha east coast of india this research work describes the shoreline change rate variations of ganjam district of odisha east coast of india for the past 24 years seven shorelines were extracted from multidated satellite images and shoreline change rate has been calculated by using digital shoreline analysis system long term shoreline change rate 1990 2014 of the study area has been calculated using weighted linier regression method short term changes have been computed for different time scales i e 1990 1999 1999 2006 2006 2008 2008 2013 and 2013 2014 using end point rate method the results obtained from the study show that 71 65 of ganjam coast shows accretion pattern and 28 35 of coast falls under erosion category high erosion is mainly noticed in northern side of gopalpur port which is mainly due to recent construction activities short term results reveals that 2006 2008 period shows maximum erosion and 1999 2006 period exhibit maximum accretion in ganjam coast from short term analysis it is observed that shoreline in the study area shows cyclic nature of erosion and accretion pattern the study reveals that tropical cyclones and human activities such as port development construction of breakwaters and groins are the major factors responsible for shoreline erosion in the study area

human impact on land ocean sediment transfer by the world s rivers abstract land ocean transfer of sediment by rivers is a key pathway for material transfer on earth contemporary data on the sediment loads of rivers provide clear evidence of significant recent changes in the sediment fluxes of several rivers in response to human impact the key drivers of increased sediment loads include land clearance for agriculture and other facets of land surface disturbance including logging activity and mining although programmes for soil conservation and sediment control can result in reduced sediment loads the trapping of sediment by dams represents the dominant cause of reduced loads this influence is currently assuming increasing importance at the global scale any attempt to link these drivers to changes in the global land ocean sediment flux must take account of the aggregation and buffering effects that operate in larger basins which can cause damping and even removal of signals of increasing flux within the upstream basin and complicate the link between upstream and downstream response to human impact further work is required to provide a precise quantitative assessment of the human impact on global land ocean sediment fluxes and the net effect of increasing and decreasing fluxes particular attention must be paid to the temporal perspective and the variation of impact trajectories in different areas of the globe and for river basins of different sizes

eustatic and tectonic controls on quaternary ras leona marine terraces strait of gibraltar northern morocco well preserved quaternary staircased marine terraces appear on ras leona limestone relief this is a peculiar sector of the betic rif cordillera lying in the four way junction between the atlantic and the mediterranean and europe and africa the age and altitude correlation of the ras leona terraces with travertine covered lateral equivalent terraces fashioned in the neighbouring beni younech area and comparison with those along the moroccan atlantic coasts would suggest that the ras leona terraces were mainly formed by eustatic factors the importance of the eustasy is supported by further comparisons with spanish and moroccan mediterranean terraces and with different marine terraces developed on passive margin coasts around the world a tectonic event occurred mainly during the period between the formation of the maarifian and the ouljian terraces i e between 370 and 150 ka the moderate quaternary tectonic uplift deduced from the marine terraces and its comparison with uplifted marine terraces developed in active subduction setting disagrees with the model of an active eastwards subduction below the gibraltar tectonic arc

a coastal reservoir of terrestrial resources for neanderthal populations in north eastern iberia palaeoenvironmental data inferred from the small vertebrate assemblage of cova del gegant sitges barcelona coastal areas as reservoirs of resources for hominid groups have been widely studied in recent years these areas combine marine with terrestrial and wetland resources and would have been optimum sites for hominids including neanderthals this is the case with the cova del gegant a cave that today opens directly onto the mediterranean sea and is located in the north eastern iberian peninsula the geomorphological evolution of the massis del garraf has provided evidence that during the late pleistocene there was a littoral platform between 8 and 13 km wide in front of the cova del gegant within this framework the data derived from analysis of the small vertebrates and large mammals recovered from cova del gegant including taxa currently absent from the massis del garraf suggest that the landscape surrounding the cave provided a richer terrestrial ecosystem for neanderthals than is available in this zone today analysis of the small vertebrate association from the cave reveals that the landscape surrounding the cave was dominated by woodland edge and open environments and that the climate was mediterranean the results have been compared with the only iberian site with similar characteristics to the cova del gegant gorham s cave southern iberia gibraltar revealing differences and similarities in the landscape and climate on the basis of the small mammal assemblages as well as the differences in the accessibility to terrestrial mammalian resources for the neanderthal groups the landscape and the climate were reasonably similar at the two sites but the differences in the accessibility of resources for the neanderthals are directly related to the location of the sites and the coastal position whereas the cova del gegant was on a route of mammal migration between the ebro valley and france suited for securing terrestrial resources gorham s cave is located on a small peninsula with a lower abundance of terrestrial mammal resources this is probably why the neanderthal groups at gorham s cave exploited marine resources whereas there is no evidence of marine resources having been exploited at cova del gegant even though the seashore was nearby copyright 2011 john wiley sons ltd

the effect of biological activity caco3 mineral dynamics and co2 degassing in the inorganic carbon cycle in sea ice in late winter early spring in the weddell sea antarctica a large scale geographical study of the ice pack in the seasonal ice zone of the weddell sea antarctica took place from september to october 2006 sea ice brines with a salinity greater than 58 and temperature lower than 3 6oc were sampled from 22 ice stations the brines had large deficits in total alkalinity and in the concentrations of the major dissolved macronutrients total dissolved inorganic carbon nitrate and soluble reactive phosphorus relative to their concentrations in the surface oceanic water and conservative behaviour during seawater freezing the concentration deficits were related to the dissolved inorganic carbon consuming processes of photosynthesis caco3 precipitation and co2 degassing the largest concentration deficits in total dissolved inorganic carbon were found to be associated with caco3 precipitation and co2 degassing because the magnitude of the photosynthesis induced concentration deficit in total dissolved inorganic carbon is controlled by the size of the inorganic nutrient pool which can be limited in sea ice by its openness to exchange with the surrounding oceanic water

holocene evolution and anthropocene destruction of the krishna delta on the east coast of india delta lobe shifts human impacts and sea level history abstract the holocene evolution of the krishna delta was inferred using landform characteristics and 11 sediment cores with 59 accelerator mass spectrometry 14c dates the landform assemblages in a 5880 km2 area of the krishna delta indicate an upper landward river built fluvial plain and a lower seaward marine built beach ridge plain holocene sediment unconformably overlying a pleistocene basement consists of 11 sedimentary facies mainly shallowing upward and deltaic succession sea level indicators such as the basal mangrove peat layers above the pleistocene basement and the foreshore sediments indicate that the sea level rose from 9 m to 3 m during 8 3 6 3 cal ky bp and stabilised at the present level around 5 cal ky bp the 3539 km2 area of the krishna delta beach ridge plain developed in five major stages during the last 6 cal ky with distinct lateral and seaward migration of delta lobes depocentre shifts delta progradation accelerated in the last 500 years forming an out building lobate delta however predominant erosion along the sediment starved coast during the past five decades due to impoundment of riverine inputs at the burgeoning upstream dams has pushed the krishna delta into a persistent destruction phase

stress pattern in portugal mainland and the adjacent atlantic region west iberia the portuguese mainland territory is located close to the azores gibraltar plate boundary in a tectonic setting responsible for significant neotectonic and seismic activities however few data concerning the present regional lithospheric stress field were available as testified by recently published maps of stress indicators for the europe and mediterranean regions one of the authors already presented a synthesis on this subject cabral 1993 where geological and geophysical stress indicators were considered in this paper we introduce new information mainly a considerable amount of borehole breakout data the updated data set comprises 32 reliable stress indicators showing a mean azimuth of 145 standard deviation 21 for the maximum horizontal stress direction shmax on the average the geological data are rotated clockwise and the focal mechanism data deviated anticlockwise to that azimuth while the borehole elongation results are consistent with the mean shmax trend these differences in stress trend suggest a regional progressive rotation of the shmax direction from nnw sse to wnw ese since the upper pliocene to estimate stress trajectories new and published stress indicators in the adjacent atlantic area and northern africa were also investigated showing a very uniform nw se shmax trend in west iberia a high level of horizontal compressive stress acting oblique to the western portuguese continental margin is inferred and interpreted in view of a proposed regional geodynamical model of activation of this passive margin with the nucleation of a subduction zone in the atlantic sw of iberia at the gorringe submarine bank which is propagating northward along the base of the continental slope at the transition between thinned and normal continental crust

coastal deformation and sea level changes in the northern chile subduction area 23 s during the last 330 ky abstract the nazca south american plate boundary is a subduction zone where a relatively complex pattern of vertical deformation can be inferred from the study of emerged marine terraces along the coasts of southern peru and northern chile the vertical distribution of remnants of pleistocene terraces suggests that a crustal large scale uplift motion is combined with more regional local tectonic processes in northern chile the area of hornitos 23 s offers a remarkable sequence of well defined marine terraces that may be dated through u series and aminostratigraphic studies on mollusc shells the unusual preservation of the landforms and of the shell material which enabled the age determination of the deposits is largely due to the lengthy history of extreme aridity in this area the exceptional record of late middle pleistocene to late pleistocene high seastands is also favoured by the slight warping of two distinct fault blocks that have enhanced the morphostratigraphic relationships between the distinct coastal units detailed geomorphological sedimentological and chronostratigraphic studies of the hornitos area led to the identification with reasonable confidence of the depositional remnants of sea level maxima coeval with the oxygen isotope substages 5c 5e 7 probably two episodes and the isotope stage 9 series of beach ridges the coastal plain at the foot of the major coastal escarpment of northern chile appears to have been uplifted at a mean rate of 240 mm ky in the course of the last 330 ky from the elevation of the older terraces and late pliocene shorelines it can be inferred that these steady vertical motions were much more rapid than during the early pleistocene

the benzu rockshelter a middle palaeolithic site on the north african coast abstract the rockshelter of benzu has a middle upper pleistocene stratigraphic sequence with ten levels seven with evidence of human occupation speleothems have been dated by u th and the sedimentary levels by osl and tl showing that the sequence extends from 250 ka to 70 ka in this paper we summarise the results of geomorphology chronostratigraphy and excavation and provide preliminary results on the pollen faunal and lithic remains the location of the site on the north african coast of the strait of gibraltar offers the potential to throw light on contacts and relationships between prehistoric communities in north africa and the south iberian peninsula for whom the strait may have served as a bridge rather than a barrier

palaeogeography and evolution of the godavari delta east coast of india during the holocene an example of wave dominated and fan delta settings abstract we investigated the holocene evolution of the godavari delta along the east coast of india by analyses of landforms and 11 borehole cores collected from the delta plain during 2010 2013 with 113 14c dates the godavari delta covering an area of 5820 km2 is one of the world s largest wave dominated deltas fringed by a 30 km wide beach ridge plain our analysis of sediment facies and their ages indicated that the holocene marine sequence thickens seaward from 10 m to more than 50 m and that the local relative sea level rapidly rose from 43 5 m to 7 5 m below the present sea level during 10 9 8 0 cal ky bp followed by a slow rise up to its current level around 5 cal ky bp spatio temporal variations in sediment accumulation rates and palaeo shorelines for the last 6 ky revealed successive changes of the main depocentre delta lobe we recognised six stages of delta evolution with distinct cyclic shifts of delta lobes controlled by avulsions a linear beach ridge located 12 14 km inland from the present shoreline which separates the first three lobes from the last three represents the effect of coastal erosion of past cuspate delta lobes as does the current linear shoreline of the central part of the delta our study documents continuous net progradation during the holocene on millennial to centennial time scales however a considerable decrease of sediment discharge due to dam construction and water diversion since the 1970s has exacerbated coastal erosion resulting in shrinking of the godavari delta plain and tipping it into a persistent destruction phase

holocene environmental changes of the godavari delta east coast of india inferred from sediment core analyses and ams 14c dating abstract the godavari delta in india is a major wave dominated delta of a tropical monsoon fed river with one of the largest sediment deliveries in the world while several earlier studies revealed the nature of landforms and progradation style of the delta plain during the holocene the present study attempts to reconstruct the depositional environment of the godavari delta through the analysis of core sediment and accelerator mass spectrometry ams 14c dating from three locations the sediment core obtained from a 27 06 m deep borehole at vilasavilli vv supported by 13 14c dates revealed the complete succession of the holocene deposits unconformably overlying pleistocene sediments textural analysis indicates the lower upward fining and upper upward coarsening units in the holocene succession total organic carbon toc total nitrogen tn ratios of 20 high content of toc around 1 5 2 5 and black to very dark colored sediment throughout the muddy part of the holocene succession indicated a predominance of terrigenous material the vv core and two other cores drp and sdg with 14 14c dates indicated the thickness of the holocene sediments in the godavari delta plain is in the order of 20 50 m unconformably resting on a seaward sloping pleistocene basement sediment facies and sediment accumulation of the three cores show the evolution of the godavari delta a transgressive phase is recognized as an upward fining succession in the vv core 8 4 8 0 cal ky bp followed by a low accumulation period 8 0 6 3 cal ky bp including the holocene maximum transgression in the godavari delta after 6 3 cal ky bp areas of high accumulation rates have changed laterally between the central part vv site and southwestern part drp and sdg sites may be controlled by the location of river mouths further analysis coupled with 11 more 14c dates compiled from earlier works indicated that the strandplain of the godavari delta prograded seaward in three stages and that the rate of progradation accelerated during the past 3 ky particularly in the last millennium however pronounced shoreline erosion led to a net negative growth of the delta during the recent decades due to sediment retention by upstream dams although this study provided insights into the sedimentation patterns and rate of seaward progradation of the godavari delta further studies on three dimensional volume analysis of the deltaic sediments are necessary to estimate the overall rates of past sediment discharge and the holocene growth of the godavari delta

do river deltas in east india retreat a case of the krishna delta abstract the construction of multiple dams and barrages in many indian river basins over the last few decades significantly reduced river flow to the sea and affected the sediment regime more reservoir construction is planned through the proposed national river linking project nrlp which will transfer massive amounts of water from the north to the south of india the impacts of these developments on fertile and ecologically sensitive deltaic environments are poorly understood and quantified at present in this paper an attempt is made to identify locate and quantify coastal erosion and deposition processes in one of the major river basins in india the krishna using a time series of landsat images for 1977 1990 and 2001 with a spatial resolution ranging from 57 0 m to 28 5 m the dynamics of these processes are analyzed together with the time series of river flow sediment discharge and sediment storage in the basin comparisons are made with similar processes identified and quantified earlier in the delta of a neighboring similarly large river basin the godavari the results suggest that coastal erosion in the krishna delta progressed over the last 25 years at the average rate of 77 6 ha yr 1 dominating the entire delta coastline and exceeding the deposition rate threefold the retreat of the krishna delta may be explained primarily by the reduced river inflow to the delta which is three times less at present than 50 years ago and the associated reduction of sediment load both are invariably related to upstream reservoir storage development

late pleistocene raised beaches of coastal estremadura central portugal abstract we present new stratigraphic sedimentological and chronological data for a suite of tectonically raised beaches dating to marine isotope stages 5 4 and 3 along the estremadura coast of west central portugal the beach deposits are found in association with ancient tidal channels and coastal dunes pollen bearing mud and peat and middle paleolithic archaeological sites that confirm occupation of the coastal zone by neanderthal populations the significance of these deposits is discussed in terms of the archaeological record the tectonic and geomorphic evolution of the coast and correlation with reconstructions of global climate and eustatic sea level change direct correlation between the estremadura beach sections is complicated by the tectonic complexity of the area and the age of the beach deposits which are near or beyond the limit of radiocarbon dating evidence from multiple sites dated by ams radiocarbon and optical luminescence methods suggests broad synchroneity in relative sea level changes along this coast during marine isotope stage 3 two beach complexes with luminescence and radiocarbon age control date to about 35 ka and 42 ka recording a rise in relative sea level around the time of heinrich event 4 at 39 ka depending on assumptions about eustatic sea level at the time they were deposited we estimate that these beaches have been uplifted at rates of 0 4 4 3 mm yr 1 by the combined effects of tectonic halokinetic and isostatic processes uplift rates of 1 2 mm yr 1 are likely if the beaches represent sea level stands at roughly 40 m below modern as suggested by recent eustatic sea level reconstructions evidence from coastal bluffs and the interior of the study area indicates extensive colluvial fluvial and aeolian sedimentation beginning around 31 ka and continuing into the holocene these geomorphic adjustments are related to concomitant changes in climate and sea level providing context that improves our understanding of late pleistocene landscape change and human occupation on the western iberian margin

correlated oceanic and continental records demonstrate past climate and hydrology of north africa 0 140 ka analysis of pollen and dinocysts in a core from the eastern atlantic core v22 196 lat 13 degree 50 n long 18 degree 57 w provides the first continuous record of paleoclimate and paleohydrology for the latest climatic cycle during interglacial intervals increases in pollen input from humid vegetation zones are correlative with high dinocyst productivity this data shows a close coincidence of northward extensions of sudanian and guinean vegetation zones in north africa and increases in fresh water input into the atlantic direct evidence indicates positive hydroclimatic phases at 135 125 103 80 47 and 12 10 ka coincident with widespread continental records of high lake levels that confirm the validity of the u th chronology

migration patterns of neolithic settlements on the abandoned yellow and yangtze river deltas of china archaeological records of the neolithic settlements on the eastern china coast between 35 n and 30 n an area covering the abandoned yellow river and the yangtze river delta plains reveal that neolithic people moved from the yellow river basin onto the northern coast for fishing hunting and dry land agriculture 7000 yr ago marine transgression interrupted their activities on the low lying 2 5 m in elevation coastal wetlands between 6000 and 5000 yr ago after which they reclaimed their land near the river mouths their migration routes on the southern yangtze delta plain indicate another scenario early neolithic communities moved onto the plain for wet rice cultivation despite relative sea level rise from 7000 to 4000 yr ago a large number of settlements were established on the lowlands between the eastern chenier ridges and the western taihu lake depression the chenier ridges with 1 0 m higher topography than the adjacent coastal area played a role in sheltering the neolithic people subsequently settlements waned considerably possibly due to further marine inundation combined with cold climate the present study shows that migration patterns of the neolithic settlements are closely associated with a gradually rising sea level between 7000 and 4000 yr ago

mississippi delta subsidence primarily caused by compaction of holocene strata coastal subsidence causes sea level rise shoreline erosion and wetland loss which poses a threat to coastal populations this is especially evident in the mississippi delta in the southern united states which was devastated by hurricane katrina in 2005 the loss of protective wetlands is considered a critical factor in the extensive flood damage the causes of subsidence in coastal louisiana attributed to factors as diverse as shallow compaction and deep crustal processes remain controversial current estimates of subsidence rates vary by several orders of magnitude here we use a series of radiocarbon dated sediment cores from the mississippi delta to analyse late holocene deposits and assess compaction rates we find that millennial scale compaction rates primarily associated with peat can reach 5mm per year values that exceed recent model predictions locally and on timescales of decades to centuries rates are likely to be 10 mm or more per year we conclude that compaction of holocene strata contributes significantly to the exceptionally high rates of relative sea level rise and coastal wetland loss in the mississippi delta and is likely to cause subsidence in other organic rich and often densely populated coastal plains

geology geography and humans battle for dominance over the delivery of fluvial sediment to the coastal ocean abstract sediment flux to the coastal zone is conditioned by geomorphic and tectonic influences basin area and relief geography temperature runoff geology lithology ice cover and human activities reservoir trapping soil erosion a new model termed bqart in recognition of those factors accounts for these varied influences when applied to a database of 488 rivers the bqart model showed no ensemble over or underprediction had a bias of just 3 across six orders of magnitude in observational values and accounted for 96 of the between river variation in the long term 30 years sediment load or yield of these rivers the geographical range of the 488 rivers covers 63 of the global land surface and is highly representative of global geology climate and socioeconomic conditions based strictly on geological parameters basin area relief lithology ice erosion 65 of the between river sediment load is explained climatic factors precipitation and temperature account for an additi

high resolution multiproxy records of sedimentological changes induced by dams in the sept iles area gulf of st lawrence canada abstract a multiproxy approach was performed on two sediment box cores sampled in the nw gulf of st lawrence in order to better understand the impacts of recent climatic or land use changes on the sedimentary regime in the proximal offshore zone multibeam and seismic surveys allowed for the careful selection of coring sites the chronology of the cores was established by 210 pb measurements and validated with coinciding historical weather events recorded in both cores confirming that the sediments are recent last 370 years the lithological variations in the cores were quantified using 1 stratigraphic markers and grain size measurements 2 high resolution x ray micro fluorescence xrf and 3 physical and magnetic tracers the grain size measurements allowed the identification of a major flood around ad 1844 4 years whereas a drastic decrease in variations and in the median grain size d50 occurred around ad 1900 highlighting the offshore impact of the sm1 dam construction on the sainte marguerite river in the early 1900s sedimentological variations have been investigated by wavelet analysis using xrf data and the sharp disappearance of high frequencies

predicting the terrestrial flux of sediment to the global ocean a planetary perspective a new model for predicting the long term flux of sediment from river basins to the coastal ocean is applied to a global data set of 340 river basins the model is based on relief basin area or averaged discharge and basin averaged temperature basinaveraged temperature is determined from basin location latitude longitude and the lapse rate across the basin relief hypsometric approximation the sediment flux model incorporates climate through basin temperature and hydrologic runoff solutions are provided for each of the major hemispheric climate regions polar temperate and tropic the model successfully predicts the pre anthropogenic flux of sediment to within the uncertainties associated with the global observations within a factor of two for 75 of rivers that range across five orders of magnitude in basin area and discharge most of the problem rivers are associated with low observational loads often smaller rivers where anthropogenic impacts are often magnified and temporal variability is high model predictions provide a baseline for researchers 1 to question the quality of observational data where available and disagreement is greatest 2 to examine a river basin for unusually large anthropogenic influences i e causes of erosion or causes of hinterland sediment retention and 3 to uncover secondary factors not addressed by our model lithology lakes the model provides a powerful tool to address the impact of paleo climate fluctuations warmer colder wetter drier on the impact of sediment flux to the coastal ocean d 2003 elsevier b v all rights reserved

coseismic vs climatic factors in the record of relative sea level changes an example from the last interglacials in se spain abstract trying to decipher how paleoseismic activity has influenced the altitudinal disposition of interglacial deposits is one of the main challenges to be confronted before quantifying relative sea level changes between consecutive highstands at the same time identifying paleoseismic features in an area with low instrumental seismic activity can complement the seismic record thereby contributing to better seismic hazard knowledge in this regard cope basin se spain meets all the requirements necessary for these kinds of analysis firstly on account of its excellent outcrop conditions and secondly because its sea level record is undoubtedly conditioned by both factors climatically driven changes and local and regional seismotectonics the morpho sedimentary sequence presented in this paper provides evidence from three different highstands two littoral sedimentary units separated by terrestrial deposits and affected by liquefaction paleoseismic activity and a younger paleo cliff and its associated wave cut platform carved into those sedimentary units this wave cut platform now tilted and folded reaches heights ranging from 0 to 8 m which has been interpreted as a consequence of cosesimic effect the age of this wave cut platform last interglacial or holocene supports uplift rate estimations of from 0 016 to 0 15 mm yr since the last interglacial holocene active deformation observed on pleistocene holocene sea level geomarkers can not only furnish useful information about seismic activity within the major structure of the aguilas arc but also offer new insight into the cope basin s geodynamic model

modeling the effect of late quaternary interglacial sea levels on wave cut shore platforms abstract a mathematical wave erosional model was used to study the effect of high sea levels during the penultimate oxygen isotopic stage 7 and last interglacials substage 5e and in the late holocene stage 1 on the present morphology of wave cut shore platforms sea level was considered to have been either the same as today or 2 25 m lower during the penultimate interglacial and 2 25 4 5 or 6 75 m higher than today during the last interglacial stage the model suggested that inherited gently sloping shore platforms in resistant rocks may be essentially protected today from erosion by high storm waves the lowest platform gradients were in runs with mesotidal 3 m range and usually with low wave periods low surf attenuation rates and weak rocks modern platform gradients increased with the difference in elevation between sea levels during successive interglacial stages shore platforms were widest in runs in which sea level was the same as today in the penultimate interglacial and 4 5 m higher than today during the last interglacial constant sea level and high last interglacial sea levels with considerable overlapping between the zones of high duration values between the mean neap high and low tidal levels in stages 7 5e and 1 were conducive to the development of wide shore platforms whereas sea levels lower than today s in stage 7 tended to produce narrower platforms in general higher sea levels during the last interglacial tended to produce higher cliff platform junctions than constant sea level unless the sea was lower than today during the penultimate interglacial stage there was a lack of supratidal ledges in macrotidal 9 m model runs with high initial gradients this suggests that gently sloping inherited shore platforms are essential for the subsequent development of supratidal nonstructural ledges in high tidal environments during periods of higher sea level intertidal ledges developed in the upper portion of the modern intertidal zone under a variety of tidal and sea level conditions these ledges can develop independently of lithological or structural influences and without any change in sea level a single high sea level may also simultaneously produce two ledges at different supratidal elevations in mesotidal environments

neotectonics and shoreline history of the rock of gibraltar southern iberia abstract several sets of staircased quaternary marine deposits can be observed along the gibraltar coast ranging from 1 to 210 m above the present mean sea level geomorphological mapping establishes from the relationship between shore scree and dune sedimentary formations five main morphotectonic steps on the rock marine terraces between 1 and 25 m 30 60 m 80 130 m 180 210 m and above each terrace level and its slope aeolian linked sediments is backed by a steep relict sea cliff margin so forming a composite cliff the most recent coastal landforms and sediments are associated with the last 250 ka linked to oxygen isotope stages ois 1 3 5 and 7 these landforms determine a morphosedimentary highstand lowstand sequence with several staircased and offlapped episodes comprising a major morphotectonic step a well developed palaeocliff usually separates the highstand marine terraces of ois 9 from those of ois 7 the gibraltar mean tectonic uplift value of 0 05 0 01 mm yr is maintained from 200 ka to the present before this at least to 250 ka the mean uplift rate was higher 0 33 0 05 mm yr possibly compatible with major tectonic events in response to a nnw sse compressive stress field between africa and iberia

heavy metal distribution in sediments of krishna river basin india suspended and bed sediments collected from the entire region of the krishna river and its major tributaries were analyzed for heavy metals v cr mn fe co ni cu zn and pb by the thin film energy dispersive x ray fluorescence technique there is considerable variation in the concentration of elements towards downstream which may be due to the variation in the subbasin geology and various degrees of human impact suspended particles are enriched in heavy metals throughout the basin relative to bed sediments the heavy metals are enriched in coarse size fractions 10 90 m throughout the krishna river except its tributary bhima where finer fractions 2 m dominate transition elements correlate very well with each other there is a striking similarity between the bed sediments of krishna river and the indian average when the annual heavy metal flux carried by the krishna river was estimated and viewed in relation to the other major riverine transport the krishna is seen to be a minor contributor of heavy metals to the bay of bengal

interglacial sea levels abstract isotopic curves have been used as approximative estimators of global sea level calculations of the amplitude of sea level variations during interglacials especially for the last interglacial are based on the study of emerged coral terraces the application of different dating methods shows great uncertainty about the length of each interglacial and also about the number chronology and altitude of the different highstands that occur during each interglacial data of raised marine terraces from areas with different geodynamic behaviour bermudas bahamas peru chile italy and spain are summarized in order to analyze the relationships between sea level and interglacial stages two interglacials have been identified for the early pleistocene represented by two marine terraces with different highstands during the early middle pleistocene an interglacial with several highstands is recorded in uplifted areas during isotopic stage 11 at least one highstand with sea level equal or higher than present has been recorded similar sea level behaviour can be suggested for isotopic stage 9 all the analyzed areas record two highstands during isotopic stage 7 when warm equatorial fauna migrate into the mediterranean during isotopic substage 5e at least two highstands took place with evidence of lowstands between them and at least one highstand during substage 5c with similar sea level height above present msl except in barbados and bermuda during substage 5a at least one highstand has been recorded

wave influence in the construction shaping and destruction of river deltas a review abstract waves are an important agent in the construction shaping and destruction of river deltas notwithstanding the commonality of waves in oceans and seas wave influence on deltas varies considerably depending on the coastal morphology and nearshore bathymetry although there have been advances in understanding the way waves approaching a delta shape its shoreline much still remains to be known of the interactions between waves and river deltas deltas are built essentially from sediments supplied by rivers sand sized and coarser sediments may also be derived from nearby abandoned delta lobes or from older relict nearshore deposits transported by wave reworking and longshore currents alternatively delta erosion by waves can also release sediment that is redistributed alongshore or that accumulates offshore the extent to which bedload is supplied to and sequestered in or lost by deltas through waves and longshore transport strongly depends on interactions between waves and fluvial discharge at the river mouth these interactions and the mutual adjustments they engender are not only important in the overall balance between delta retreat progradation or aggradation but also in processes such as avulsion and channel switching as well as in the eventual survival of a delta in the face of sea level rise where waves are important fluvial liquid discharge is high and sediment supply is rich in bedload two important aspects are the blocking of waves and longshore currents by strong river discharge and the formation of bars at the river mouth field studies of the complex interactive processes prevailing where river flows encounter waves are however non existent and numerical modelling though promising hampered by scale constraints and the difficulty of replicating them and generating mouth bars in the presence of longshore currents this interaction influences the seaward extent of the delta mouth protuberance and its stability this protuberance then forming the regional shoreline template to which waves and longshore currents adjust longshore currents can redistribute wave reworked mouth bar deposits emplaced during strong river flow transport may be either divergent from the mouth or may be regionally unidirectional but wherein the symmetry of some deltas probably rare may be maintained by a strong river blocking effect on transport from the updrift flank the mouth protuberance may be such as to foster transport reversal counter drift at the delta margins that contributes to sediment sequestering within the delta these interactions largely contribute in shaping delta shorelines and together with the abundance of sediment supply and grain size determine the resultant wave formed shoreline barrier types which include spits more or less closely spaced beach ridges and barrier islands and cheniers in situations of punctuated progradation or retreat where several distributary mouths occur pronounced longshore variability in wave processes and wave induced sediment transport may ensue resulting in multiple drift cells that assure the retention of sand and coarse grained sediments within the delta waves can also be an important agent in the reworking and retreat of mud rich deltas that generally conform in morphology to the river dominated such as the mississippi or tide dominated such as the ganges brahmaputra or chao phraya types resulting in the episodic formation of sandy cheniers and beach ridges although sea level rise is likely to lead to enhanced wave reworking of deltas the possible prevalence of aggradation in lieu of progradation channel switching and avulsion and washover processes may contribute to the disorganization of waves and longshore transport fostering deltaic sequestering of sand and coarser sized sediment and delta survival the weakening of river discharges resulting from human activities will invariably lead however to enhanced wave reworking of deltas and to deltaic sediment redistribution by longshore currents the massive swing towards significant reductions in fluvial sediment supply today may signify the ultimate demise of many deltas in the coming decades through a process of delta shoreline straightening by waves in addition to accelerated sinking these various foregoing aspects of the relationship between waves and river deltas are reviewed here across a range of timescales and new interaction concepts proposed using numerous examples of deltas in the world and on the basis of case studies conceptual studies and numerical modelling studies in the literature spanning more than forty years

morphosedimentary evolution of a delta sourced drift aligned sand barrier lagoon complex western bight of benin the coast of eastern ghana and togo is bounded by a major holocene sand barrier complex hinged on the volta delta to the west and subject to high rates of longshore sand drift 1 1 5 106 m3 yr in spite of its proximity to this major deltaic sediment source this barrier system shows marked longshore variations in progradation following the middle holocene eustatic stillstand it is a hybrid system in terms of internal facies composition and plan view morphology in that it has evolved from an essentially regressive to a stationary synonymous with cessation of progradation system both transgressive and barrier inlet facies have also developed through time and space these temporal and spatial changes in patterns of development reflect variations in longshore sand transport and deposition over the last 5000 years such variations have been controlled by sediment supply from the volta by antecedent topography by lagoonal and river drainage by sediment cell development and maturation and in the very recent past by anthropogenic perturbation barrier progradation in the western bight of benin diminished considerably or ceased probably as early as 3400 yr b p as a single major equilibrium drift aligned bight cell matured permitting transport of volta sand toward the rest of the eastern bight in benin and nigeria the eastward longshore supply from the volta has involved both direct inputs of upland derived sand by the volta river channel and reworking of nearshore deltaic deposits a recent reduction in direct fluvial supply exacerbated by the akosombo dam completed in 1961 has induced a wave of erosion of the downdrift delta mouth barrier and shoreface deposits to fulfil the strong drift requirements in togo construction of a deepwater port in 1967 has also affected the barrier system both of these changes have had considerable impacts on longshore sediment dynamics the most significant impact has been segmentation of the former unique sediment cell characterising the 400 km long bight of benin coast resulting in differential longshore erosion progradation or equilibrium these changes have also induced new patterns of barrier behaviour that include transgressive and regressive dynamics at various locations alongshore

coastal uplift in continental collision plate boundaries data from the last interglacial marine terraces of the gibraltar strait area south spain abstract the spatial height analyses of deposits belonging to isotopic substages 5e and 5c indicate the occurrence of differential uplift in the gibraltar strait area maximum mean uplift rates do not reach values of 0 2 mm year displaying a gentle deceleration from 0 15 to 0 10 mm year for the last 128 ka maximum estimated rates are recorded in the central sector of the gibraltar strait the combined analysis of the accumulated vertical movements before and after iss 5c indicates that differential uplift is accommodated along ne sw sinistral and nw se dextral mostly inherited strike slip fault systems separating coastal segments of contrasting uplifting subsiding behaviour the occurrence of inversions in the relative vertical offsets along some of these faults arises when this combined analysis is performed a model of asymmetric pure shear defined by these two fault systems generated in response to the roughly n s convergence between the african and eurasian plates can explain the recorded uplift patterns in this transpressive setting generated by the africa eurasia continental collision the recent convergence 4 mm year is mostly released by shear processes and subsidiary e w horizontal extension whilst the recorded coastal uplift only represents a low percentage of the recent convergence rates

geologic evolution of the betic cordilleras in the western mediterranean miocene to the present abstract the betic cordilleras were formed during the eo meso and neo alpine evolution of the western mediterranean area during the neo alpine stage the northward subduction of the african plate took place and the algerian provencal basin opened with the creation of oceanic floor associated space problems produced the expulsion and extensive stretching of the internal zones to the west which in turn disrupted and deformed the external zones of the betic and rif cordilleras these occurrences essentially took place in the burdigalian and continued with diminished intensity into the middle miocene following the suturing of the transcurrent contact between the internal and external zones important n60 90 e and nw se faults occurred the betic cordilleras are characterized as having been deformed by regional horizontal shortening compression oriented wnw ese or nw se which gradually rotated to the nnw sse in the late miocene when its most important intramontane neogene basins were formed the alboran basin with a thinned continental crust was formed as a western prolongation of the opening of the algerian provencal basin with its basic features already apparent in the burdigalian the volcanism present in the southeast of the betic cordilleras and in northeast morocco crossing the alboran basin is mainly late miocene in age it is linked to fracturing and exhibits chemistry related to the different thickness of the crust

holocene and late pleistocene relative sea level fluctuations along the east coast of india abstract hermatypic coral colonies and intertidal fossil bearing grainstone packstone and sandstone beds of holocene and of a late pleistocene highstand are exposed above the present high tide level htl at a number of locations along the east coast of india from cape comorin to rameswaram being a passive margin boundary free from indications of late quaternary seismogenic movements this sector provides a benchmark for defining minor relative sea level perturbations during the late pleistocene and holocene highstands along a tropical coast lying between latitudes 5 n and 10 n a series of marine terraces carved on and locally blanketted by late pleistocene biotic and terrigenous accumulations occur at different elevations up to 4 4 m above ltl at manappad point possibly signifying discrete stillstand episodes followed by abrupt intervals of rising falling sea level sea level indicators of the holocene highstand occur in this sector as well as along the fringes of the godavari delta further north the holocene highstand reached nearly 3 m above ltl at 7 3 ka remained stable for approximately 1 7 kyr and was followed by a relative sea level fall between 5 2 and 4 2 ka there was a second pulse of relative sea level rise of a few metres leading to a fresh spurt in coral growth along the northern coast of mandapam and rameswaram this was nearly contemporaneous with fresh melting of ice sheets of antarctica the little ice age lia witnessed a minor 1 m relative sea level fall along this coast resulting in rapid diagenetic hardening and infiltration of goethite into the emerged foreshore sand at karikovil and its neighbourhood this was followed by a rise of the sea level during the last few centuries

impacts of sediment retention by dams on delta shoreline recession evidences from the krishna and godavari deltas india river deltas are the major repositories of terrestrial sediment flux into the world s oceans reduction in riverine inputs into the deltas due to upstream damming might lead to a relative dominance of waves tides and currents that are especially exacerbated by coastal subsidence and sea level rise ultimately affecting the delta environment analysis of multi date satellite imagery and maps covering the krishna and godavari deltas along the east coast of india revealed a net erosion of 76 km2 area along the entire 336 km long twin delta coast during the past 43 years 1965 2008 with a progressively increasing rate from 1 39 km2 yr 1 between 1965 and 1990 to 2 32 km2 yr 1 during 1990 2000 and more or less sustained at 2 25 km2 yr 1 during 2000 2008 at present the krishna has almost become a closed basin with decreased water discharges into the delta from 61 88 km3 during 1951 1959 to 11 82 km3 by 2000 2008 and the suspended sediment loads from 9 million tons during 1966 1969 to as low as 0 4 million tons by 2000 2005 in the case of the godavari delta although the water discharge data do not show any major change there was almost a three fold reduction in its suspended sediment loads from 150 2 million tons during 1970 1979 to 57 2 million tons by 2000 2006 a comparison of data on annual sediment loads recorded along the krishna and godavari rivers showed consistently lower sediment quantities at the locations downstream of dams than at their upstream counterparts reports based on bathymetric surveys revealed considerable reduction in the storage capacities of reservoirs behind such dams apparently sediment retention at the dams is the main reason for the pronounced coastal erosion along the krishna and godavari deltas during the past four decades which is coeval to the hectic dam construction activity in these river basins copyright 2010 john wiley and sons ltd

undrowning a lost world the marine isotope stage 3 landscape of gibraltar abstract the rock of gibraltar at the south western extreme of the iberian peninsula and 21 km from the north african coast is a 6 km long limestone peninsula which was inhabited by neanderthals from mis 5e until the end of mis 3 a total of 8 sites either with neanderthal fossils or their mousterian lithic technology have been discovered on the rock two gorham s and vanguard caves are the subject of ongoing research these caves are currently at sea level but during mis 3 faced an emerged coastal shelf with the shoreline as far as 5 km away at times they hold a unique archive of fauna and flora in the form of fossils charcoal and pollen helping environmental reconstruction of now submerged shelf landscapes in addition geological and geomorphological features a 300 metre dune complex elevated aeolian deposits raised beaches scree speleothems complement the biotic picture the work is further complemented by a study of the ecology of the species recorded at the site using present day observations the species composition in this fossil record closely matches the present day fauna and vegetation of the donana national park sw spain a mosaic of pine groves coastal dunes shrubland and seasonal wetlands and currently the richest reserve in terms of biodiversity in the iberian peninsula located only 100 km to the northwest from gibraltar all this information permits for the first time the quantification of the vegetation structure of the ancient coastal plain and the modelling of the spatio temporal dynamics of the mis 3 coastal shelf off gibraltar

decadal link between longitudinal morphological changes in branching channels of yangtze estuary and movement of the offshore depo center in estuaries the morphology of inland and offshore areas usually evolves synergistically this study examines the decadal link between longitudinal changes in morphology of branching channels and movement of the offshore depo center where sediment deposition rate is maximum of the yangtze river estuary under intense human interference integrated data analysis is provided on morphology runoff discharge and ebb partition ratio from 1950 to 2017 channel volume reductions and change rates between isobaths in branching channels reflect the impact of estuarine engineering projects ebb partition ratio and duration of discharge 60 000 m3 s 1 act as proxies for the water excavating force in branching channels and runoff intensity it is found that deposition occurs in the lower upper sub reaches or further downstream upstream channels of the inland north south branching channels and the offshore depo center moves southward or southeastward as runoff intensity grows the reverse occurs as runoff intensity declines this is because the horizontal circumfluence in the yangtze estuary rotates clockwise as ebb partition ratios of the north south branching channels increase decrease for increasing runoff and conversely rotates anticlockwise for decreasing runoff land reclamation activities the deepwater channel project and the qingcaosha reservoir have impacted greatly on longitudinal changes of morphology in the north branch and the south passage and on ebb partition ratio variations in the north south channel and the north south passage dam induced runoff flattening has enhanced deposition in the upper lower sub reaches of the north south branching channels and caused northward movement of the offshore depo center except in areas affected by estuarine engineering projects dam induced longitudinal evolution of branching channel morphology and offshore depo center movement will likely persist in the future given the ongoing construction of large cascade dams in the upper yangtze and the completion of major projects in the yangtze estuary