coastal erosion processes timing and magnitudes at the bluff toe abstract five lake erie bluffs one interlaminated clay and silt three clay rich diamicts and one shale were surveyed at about 2 week intervals and after wind storms for up to 5 years erosion of the bluff toes along this low energy coast occurred during northeast wind storms which produced surges of up to 1 m and surf zone waves of up to 1 2 m wave impact and or uprush caused quarrying which removed most of the toe material and abrasion there were from 1 to 23 erosion events sites with maximum magnitudes of erosion ranging from 12 to 55 cm event timing and magnitude were linked to erodibility maximum water level storm surge storm duration and beach width a threshold maximum water level and a threshold surge were necessary for erosion at these thresholds the beach was submerged and wave energy was directly expended on the toe erosion did not take place when there was shorefast ice or when debris slopes shielded the toe from waves the originally cohesive toe materials are easily eroded when they weather to an essentially noncohesive state wave erosion is the crucial erosion process removal of material from the toe prevents the development of a stable slope

sr and nd isotope composition of late pleistocene sapropels and nonsapropelic sediments from the eastern mediterranean sea implications for detrital influx and climatic conditions in the source areas isotopic ratios of sr and nd from lithogenic components of three isochronous core sections recovered from an east west transect in the eastern mediterranean sea ems have been analyzed the data are used for a quantitative estimate of the temporal and spatial variation of detrital flux to the ems assuming saharan dust and aegean nile particulate matter as dominant end members it was established that the carbonate free saharan dust flux during deposition of the nonsapropel layers of marine oxygen isotope stage 5 4 mis 5 4 was similar to the present flux during the deposition of sapropels s5 and s6 however the saharan dust input was drastically reduced and was not balanced by a change in the riverine influx at this time denser vegetation cover during more humid conditions may have reduced physical erosion and sediment removal in the source area during marine oxygen isotope stage 6 2 mis 6 2 a pronounced increase of saharan dust and detrital influx from the aegean region is evident and implies more arid conditions in the southern and northern catchment areas during this period intersite variations are interpreted in terms of their geographic location relative to the seaways connecting the aegean sea and ems the width of the straits and hence the amount of sediment entering the eastern basins may have been affected by a low sea level that impeded interbasin sediment dispersal

site information and initial results from deep ice drilling on law dome antarctica the aim of deep ice drilling on law dome antarctica has been to exploit the special characteristics of law dome summit i e low temperature and high accumulation near an ice divide to obtain a high resolution ice core for climatic environmental studies of the holocene and the last glacial maximum lgm drilling was completed in february 1993 when basal ice containing small fragments of rock was reached at a depth of 1196 m accurate ice dating obtained by counting annual layers revealed by fine detail 18 o peroxide and electrical conductivity measurements is continuous down to 399 m corresponding to a date of ad 1304 sulphate concentration measurements made around depths where conductivity tracing indicates volcanic fallout allow confirmation of the dating for agung in 1963 and tambora in 1815 or estimates of the eruption date from the ice dating for the kuwae vanuatu eruption 1457 the lower part of the core is dated by extrapolating the layer counting using a simple model of the ice flow at the lgm ice fabric measurements show a large decrease 250 to 14 mm 2 in crystal size and a narrow maximum in c axis verticality the main zone of strong single pole fabrics however is located higher up in a broad zone around 900 m oxygen isotope 18 o measurements show holocene ice down to 1113 m the lgm at 1133 m and warm 18 o about the same as holocene ice near the base of the ice sheet the lgm holocene 18 o shift of 7 0 only 1 larger than for vostok indicates that law dome remained an independent ice cap and was not overridden by the inland ice sheet in the glacial

rapid rise of sea level 19 000 years ago and its global implications evidence from the irish sea basin supports the existence of an abrupt rise in sea level meltwater pulse at 19 000 years before the present b p climate records indicate a large reduction in the strength of north atlantic deep water formation and attendant cooling of the north atlantic at this time indicating a source of the meltwater pulse from one or more northern hemisphere ice sheets warming of the tropical atlantic and pacific oceans and the southern hemisphere also began at 19 000 years b p these responses identify mechanisms responsible for the propagation of deglacial climate signals to the southern hemisphere and tropics while maintaining a cold climate in the northern hemisphere

calibrating the ice core paleothermometer using seasonality high resolution oxygen isotope measurements on the dome summit south dss ice core from law dome antarctica provide a seasonal profile that is sufficiently stable and undistorted by biases in accumulation to permit comparison with measured temperature seasonality this comparison yields an isotope temperature relation with a gradient d dt of 0 44 0 02 c and provides a new method for exploring the isotope temperature relationship at high accumulation sites if applied to the observed isotope record from the dss core which extends through the last glacial and beyond this calibration suggests that at its coldest the last glaciation was 13 c colder than present at this site after correcting for elevation change this finding compares with a temperature difference of 8 c computed by using the local spatially derived calibration

mechanisms associated with the erosion of sand dune cliffs magilligan northern ireland a fifteen year history of coastal dune recession at magilligan northern ireland has revealed both time and space contrasts in processes and morphology since 1968 storm frequency has increased while dune retreat reached a peak 5 4 m in 1978 1979 three types of dune eroding events are noted resulting from particular wave wind tide combinations the spatial variability in dune scarping is associated with vegetation and soil development and slope failures range from granular avalanches to retrogressive rotational slumps

geochemical and sedimentological patterns in the thermaikos gulf north west aegean sea formed from a multisource of elements surface sediment samples from thermaikos gulf were analysed for organic carbon cd pb cr cu zn mn ni co and fe and were subjected to grain size analysis the results showed that pb cu and zn had the same source of pollution in the following order of importance the sewage outfall the industrial zone and the axios river the concentration of these metals increased with decreasing mean grain size suggesting their association with the fine fraction of the sediments the clays and the organic matter cadmium was more loosely correlated with the metals of the previous group being derived from the community activities and also from the weathering of land based ophiolitic rocks iron cr ni co and mn are of natural origin the weathering of mafic and ultramafic rocks being responsible for their enrichment this was more apparent in the case of ni which was more enriched in the coarser and better sorted sediments near the delta of the river aliakmon

chemical cycles in pliocene sapropel bearing and sapropel barren eastern mediterranean sediments abstract high resolution 3 4 cm investigations of major and minor elements were carried out on sediment cores from odp leg 160 sites 964 ionian basin 969 mediterranean ridge 967 and 966 northern slope and top of eratosthenes seamount south of cyprus at site 967 element al ratios display pronounced cyclic records that are related to astronomically forced climatic variations sediments from the top of eratosthenes seamount site 966 show a similar pattern to those from site 967 but they are more disturbed by bioturbation and also strongly influenced by long term variations in sediment dispersal sediments from site 969 display similar trends to those from site 964 i e they are characterized by higher mg al slightly higher k al and lower ti al ratios during sapropel formation higher ti al ratios at site 969 compared with sediments from site 964 may be explained by a westward transport of material from a source in the east where ti al ratios are highest sites 966 and 967 elevated mg al ratios at site 969 during sapropel intervals are due to river derived material transported through the kithira strait between peloponnesus and crete from the northwestern aegean sea which originates from ultramafic rocks a change in intermediate water currents current reversal during sapropel formation may explain the enhanced supply of mg rich and the relatively diminished supply of ti rich material we propose that during deposition of the reddish intervals at site 969 a change in circulation did not occur because a drastic decrease in ti al ratios is not evident in these sediments ba peaks indicative of former sapropels are not present ba enrichments in the same sapropel barren intervals at site 967 northern slope of eratosthenes seamount suggest that during such intervals the burn down process was more effective than during the sapropel bearing intervals mn contents in all investigated pliocene sediments correlate with the carbonate contents higher mn contents of the sapropel barren sediments suggest that during time intervals of sapropel formation either mn accumulation at the margins of the permanently oxic upper water column or mn export into the western mediterranean might have occured the latter could only be explained by sub or anoxic conditions in large parts of the water column

hydrothermal metallogenesis at the wilkes fracture zone east pacific rise intersection abstract two hundred and eight sediment samples from 25 gravity cores obtained in and around the wilkes fracture zone on the east pacific rise have been analysed in bulk for mn fe ni co pb zn cu ba al si and caco3 downcore metal variations suggest that apart from the present hydrothermal event which is more intense on the crest of the rise and in the western part of the fracture zone in the past two hydrothermal events occurred the end of the first event occurred about 121 000 yrs b p and that of the second event at about 85 000 yrs b p both events are recognized throughout the study area a third hydrothermal event is traced only on the crest of the rise and occurred at about 16 000 yrs b p generally in the last 90 000 years the eastern part of the wilkes fracture zone appears to have become less active in contrast to the western flank which has become more active geochemical partition analysis carried out on selected cores shows that the hydroxylamine hcl soluble fe mn ni cu and zn decrease while the proportion of these metals associated with the hcl soluble fraction increases with depth in the sediments in addition there is an increase in the proportion of the hydroxylamine hcl insoluble residue with depth from these data it is inferred that diagenetic transformation of phases occurs within the buried sediments leading to the formation of stable iron oxides and iron smectite the element partition variations are most pronounced in the upper 40 cm of the sediments and are probably associated with oxidation reduction reactions in which mn fe mn fe oxides and organic material are involved reduction of fe mn oxides may lead to the release of mn cu and zn which are subsequently incorporated in the newly formed goethite and smectite the transformation of the metalliferous sediment constituents to more stable phases increases away from the crest of the rise because the environmental conditions for the formation of smectite become more favorable i e lower temperature older sediments greater availability of al si and mg and greater physical contact between fe oxy hydroxides and sio2 in the narrow basins

modeling cyclic recession of cohesive clay coasts effects of wave erosion and bluff stability abstract a mathematical model combining the effects of wave erosion beach sediment and bluff slope stability has been developed to study the episodic cyclical recession of cohesive clay coasts the model was applied to the southern great lakes in north america which although non tidal experience seasonal fluctuations in lake level of about 0 5 m and long term fluctuations of up to 2 m model runs were designed to explore the interaction between various components of the system including profile shape bluff recession rates lake level variations beach morphodynamics the geomechanical characteristics of the material and the type slump topple and size of the slope failures model runs were made for the equivalent of 100 years quasi equilibrium conditions developed in the runs which had similar erosion rates to the field with parallel slope retreat in the upper portion of the profiles and slope decline in the lower portion temporal variations in the rate of recession of the crest of the bluff closely matched changes in lake level the model confirmed previous work that suggested that rates of bluff recession are strongly controlled by the rate of erosion below the water surface but it also provided support for a more recent proposal that rates of bluff recession also influence rates of erosion in shallow water it was found that positive and negative changes in the size of the beach can either promote or hinder bluff and profile erosion depending on local circumstances the model demonstrated that bluff height debris mobility wave undercutting and groundwater levels are key factors in determining the stability of coastal bluffs the model represents a promising new tool to forecast and thereby mitigate the effects of climate change on marine and lacustrine coasts

barrier and lagoon coast evolution under differing relative sea level regimes examples from ireland and nova scotia abstract although the coasts of southern ireland and eastern nova scotia possess many basic similarities especially in terms of geology glacial history sediment character resistance to erosion and wave and tide regimes there is a fundamental contrast in holocene sea level history in ireland recent the past 4000 years sea level rise has been limited to less than 1 mm year by contrast the atlantic coast of nova scotia has been experiencing sea level rises up to three to five times greater over the same period under these markedly differing relative sea level rise regimes barrier and lagoon evolution has varied considerably in ireland barrier lagoon form is controlled by local basement expression particularly through the emergence of headlands creating largely closed sediment systems and the requirement to maintain cross shore drainage it is this latter factor that leads to a simple four fold categorization of the irish barriers and lagoons from freshwater seepage to open tidal environments the nova scotian examples are associated with rapidly moving erosional fronts with local basement control relegated to a subordinate role at the expense of rapid changes in sediment supply barriers can both grow and decay under these conditions subject to certain critical but as yet ill defined thresholds simultaneously forcing development and destruction of adjoining lagoons these major differences also find expression in sedimentary sequences

statistical analysis of factors influencing cliff erosion along a section of the west wales coast u k cliff erosion along a section of the west wales coastline is described rockfalls mudslides and retreating fencelines are evidence of current activity measurements over a two year period 1983 85 gave mean annual recession figures of up to 0 25 m yr 1 for glacial embayments wave refraction modelling and longshore beach surveys confirmed the existence of high and low beaches factors influencing variation in recession rates were identified and measured regression analysis suggested that the volume of beach face material was the dominant explanatory variable in short term cliff erosion

natural and anthropogenic changes in atmospheric co2 over the last 1000 years from air in antarctic ice and firn a record of atmospheric co2 mixing ratios from 1006 a d to 1978 a d has been produced by analysing the air enclosed in three ice cores from law dome antarctica the enclosed air has unparalleled age resolution and extends into recent decades because of the high rate of snow accumulation at the ice core sites the co2 data overlap with the record from direct atmospheric measurements for up to 20 years the effects of diffusion in the firn on the co2 mixing ratio and age of the ice core air were determined by analyzing air sampled from the surface down to the bubble close off depth the uncertainty of the ice core co2 mixing ratios is 1 2 ppm 1 preindustrial co2 mixing ratios were in the range 275 284 ppm with the lower levels during 1550 1800 a d probably as a result of colder global climate natural co2 variations of this magnitude make it inappropriate to refer to a single preindustrial co2 level major co2 growth occurred over the industrial period except during 1935 1945 a d when co2 mixing ratios stabilized or decreased slightly probably as a result of natural variations of the carbon cycle on a decadal timescale

geochemical and micropaleontological characterisation of a mediterranean sapropel s5 a case study from core ban89gc09 south of crete several geochemical and micropaleontological proxies were studied in a well developed sapropel s5 from a core collected south of crete to investigate the causes and the mechanisms of its deposition to reconstruct the paleoenvironmental and paleoceanographical conditions at time of its formation and to detect the roles played by productivity and anoxia the geochemical proxies are also used to unravel the sediment provenance and therefore to help tracing water circulation patterns and freshwater sources the multiproxy approach reveals that the sapropel layer has high internal variability and five different depositional phases can be identified four within the visible sapropel layer an increase in temperature and the development of a deep chlorophyll maximum characterise the onset of the sapropel phase 1 with enhanced productivity being favoured by local riverine input not clearly ascribable to nile river freshwater discharge and by the shoaling of the pycnocline nutricline surface water stratification and productivity develop together with strong seafloor dysoxia anoxia phase 2 is characterised by lower stratification slightly lower temperature and or higher seasonal contrast and still high productivity phase 3 records high productivity high temperature and high stratification probably more sustained by the nile input a sudden partial re oxygenation takes place at the end of this phase changing the main features of the sapropel in the fourth phase productivity starts to decrease water stratification seems to be partially broken down and sediment oxygenation increases a transitional phase phase 5 occurs between the end of the visible sapropel and the normal pelagic post sapropel sedimentation where productivity is still high and oxygenation improves compared to the visible sapropel layer the massive occurrence of polysphaeridium zoharyi cyst of a red tide forming dinoflagellate also characterises this phase the geochemical proxies indicate that pre sapropel and post sapropel sediments are quite different from each other and the provenance shifts from a more mixed to a more markedly southern origin of sediments

chemical characteristics of the snow pits at murododaira mount tateyama japan measurements of the chemical composition of the snow pits at murododaira 2450m a s l mount tateyama near the coast of the japan sea in central japan were performed each spring from 2005 through 2008 the mean concentrations of nssso4 2 and no3 are higher than those in snowpack in the 1990s the ph and nssca2 were usually high in the upper parts of 2 3m of snow deposited in the spring when asian dust kosa particles are frequently transported high concentrations of nssso4 2 were detected in both the spring and winter layers the high nssca2 layers usually contained high concentrations of nssso4 2 the results show that not only kosa particles but also air pollutants might have been transported long range from the continent of asia the concentrations of peroxides were high in the new snow precipitation particles and granular snow coarse grain melt forms layers the peroxide concentrations in the snow layers were negatively correlated with the nssca2 concentrations high peroxide concentrations may be preserved in granular snow layers having low concentrations of nssca2

geochemical study of sediments from northern euboekos bay greece with regard to the presence of submarine mineral deposits abstract chemical analyses of surface sediment cores from northern euboekos bay greece show that this area is markedly enriched in metals e g ni cr mn relative to aegean shelf sediments these enrichments are partly related to the presence of an fe ni ore body on the seafloor formed by the dumping of a metal rich slag and partly to natural geological processes in a zone on the northwestern coast of euboea island considerable enrichments of ni cr and mn are attributed to weathering of mafic and ultramafic rocks present on the island and probably extended onto the continental shelf it is suggested that the geological and oceanographic conditions in this area are favourable for the formation of placer mineral deposits similar and even greater enrichments of fe ni cr mn zn and cu identified in two older geological horizons are associated with coarse sediments and may be the result of the following processes 1 the weathering of ophiolitic rocks or fe ni deposits or both extending from onshore below the seafloor 2 the production of greater amounts of metal rich weathering products in the past due to climatic changes and 3 lowering of the sea level at times when metal rich horizons were being formed closer to the continent

submarine hydrothermal metallogenesis associated with the collision of two plates the southern aegean sea region abstract the geochemistry of sediments from the southern aegean sea demonstrates that the active tectonics in the hellenic arc trench system favor hydrothermal mineralization processes involving leaching of oceanic crust the distribution and geochemical behavior of mn fe cu zn p and ba indicate a hydrothermal influence i at plate boundaries such as the pliny and strabon trenches ii in fore arc basins such as maleas iraklion and karpathos iii on the island arc all fore arc basins having greater mn enrichments than the trenches are also characterized by higher heat flow values the greatest mn enrichments occur at maleas basin where a mn dispersion halo is recognized this basin is very tectonically active with the largest group of normal faults along the planes of which magmatic material was injected and the highest heat flow values in the sea of crete it also falls in the eastern mediterranean zone of high seismic activity because the fe mn sediments identified in the above geotectonic units are the end members of the hydrothermal fractionation sequence known from areas where leaching of oceanic crust occurs it is suggested that other members of the sequence such as metal sulfides may be found significant geochemical anomalies of pb and zn found in areas of high heat flow and on lines of normal faulting are considered to be traces of the presence of metal sulfides

temporal patterns and processes of retreat of drumlin coastal cliffs strangford lough northern ireland abstract monthly measurements of erosion pins at sixteen sites around the very low energy marine environment of strangford lough northern ireland were used to investigate temporal patterns and processes of retreat of low cliffs of glacial material erosion rates were extremely varied the mean was 76 49 03 mm a 1 erosion is strongly seasonal with 86 6 of the total erosion occurring during winter september to march periods this seasonal pattern was most exaggerated in some of the more rapidly eroding sites on the exposed eastern side of the lough preparatory processes heavy rainfall desiccation and frost action reduce the compressive strength of the cliff materials and act as important forcing of the erodibility of the cliffs direct wave attack on cliffs around the lough takes place when threshold conditions of wind speed and tidal heights are met tidal levels 1 50 m above o d with wind speed of 15 4 m s 1 30 knots maintaining for more than 4 h during the study period eighteen events exceeding the above criteria were identified extremely low atmospheric pressure has also been identified as important in raising water levels slumps falls topples and slides were the forms of cliff failure observed

threshold height of coastal cliffs for collapse due to tsunami theoretical analysis of the coral limestone cliffs of the ryukyu islands japan abstract stability analyses were made for both gravity and wave induced collapses of coastal cliffs with a vertical failure surface to determine the threshold cliff height for tsunami induced collapses the models proposed in this study have two distinct parameters characterizing the cliff height calculations of the critical notch depth from these models show that gravity induced collapses occur on cliffs of any height whereas the threshold cliff heights for tsunami induced collapses are controlled by the height of the tsunamis the relation between the threshold cliff height and the tsunami height is represented by a power law function

critical notch depths for failure of coastal limestone cliffs case study at kuro shima island okinawa japan development of a notch at the base of a cliff reduces cliff stability and often induces a collapse pleistocene limestone coastal cliffs of elevation 5 m in kuro shima ryukyu islands have a prominent notch with a depth of 3 4 m at their bases around these coastal cliffs collapses different from previous studies of cliff collapses in the ryukyu islands were found collapses in kuro shima have a horizontal failure surface the horizontal failure surface situated at the height of the failure surface corresponding to the retreat point of the notch is bounded by vertical joints cutting the whole cliff and the reef flat in front of the cliff two types of horizontal failure surface were found triangular and quadrangular the distinction appears to depend on the angle between the vertical joints and the front face of the cliff prior to collapse these cliffs appear to have been separated from the adjacent cliffs by the development of vertical joints consequently a cliff that will collapse can be identified in advance cliff instability is strongly dependent on the development of a notch to study the effect of notch development on cliff collapse the notch depth at which collapse occurs was calculated using stability analysis instability of a cliff increases with notch depth collapse occurs at the horizontal failure surface when the ratio of the notch depth to the seaward length of the cliff is approximately 0 5 0 7 for a triangular failure surface and 0 7 0 9 for a quadrangular failure surface copyright 2010 john wiley sons ltd

vostok ice core provides 160 000 year record of atmospheric co2 direct evidence of past atmospheric co2 changes has been extended to the past 160 000 years from the vostok ice core these changes are most notably an inherent phenomenon of change between glacial and interglacial periods besides this major 100 000 year cycle the co2 record seems to exhibit a cyclic change with a period of some 21 000 years

formaldehyde and peroxide concentrations in law dome antarctica firn and ice cores peroxide speciation and formaldehyde measurements have been made on ice cores retrieved from law dome antarctica measurements were made for ice deposited during four different periods modern pre industrial holocene early holocene and last glacial maximum lgm the data show modern peroxide levels 50 above pre industrial levels at 1 6 mol l 1 and an absence of methyl hydroperoxide down to a detection threshold of 0 003 mol l 1 formaldehyde levels show a 40 increase from pre industrial to modern times rising from 0 07 mol l 1 to 0 10 mol l 1 with a further increase and possible seasonality near the surface which we associate with post depositional processes peroxide levels in lgm ice are low but formaldehyde concentrations are high at 0 13 mol l 1 relative to modern levels similar high levels of formaldehyde are seen in early holocene ice 6900 years bp

ams c 14 dating of deglacial events in the irish sea basin and other sectors of the british irish ice sheet sedimentary sequences deposited by the decaying marine margin of the british irish ice sheet biis record isostatic depression and successive ice sheet retreat towards centres of ice dispersion radiocarbon dating by accelerator mass spectrometry ams of in situ marine microfaunas that are commonly associated with these sequences constrain the timing of glacial and sea level fluctuations during the last deglaciation enabling us to evaluate the dynamics of the bus and its response to north atlantic climate change here we use our radiocarbon dated stratigraphy to define six major glacial and sea level events since the last glacial maximum 1 initial deglaciation may have occurred 18 3 kyr c 14 bp along the northwestern irish coast in agreement with a deglacial age of similar to 22 cl 36 kyr bp for southwestern ireland ice retreated to inland centres and areas of transverse moraine began to form across the north irish lowlands 2 channels cut into glaciomarine deglacial sediments along the western irish sea coast are graded to below present sea level identifying a fall of relative sea level rsl in response to isostatic emergence of the coast 3 marine mud that rapidly infilled these channels records an abrupt rise in global sea level of 10 15 m similar to 16 7 c 14 kyr bp that flooded the irish sea coast and may have triggered deglaciation of a marine based margin in donegal bay 4 intertidal boulder pavements in dundalk bay indicate that rsl similar to 15 0 c 14 kyr bp was similar to present 5 a major readvance of all sectors of the biis occurred between 14 and 15 kyr 14 c bp which overprinted subglacial transverse moraines and delivered a substantial sediment flux to tidewater ice sheet margins this event the killard point stadial indicates that the bus participated in heinrich event 1 6 subsequent deposition of marine muds on drumlins 12 7 c 14 kyr bp indicates isostatic depression and attendant high rsl resulting from the killard point readvance these events identify a dynamic biis during the last deglaciation as well as significant changes in rsl that reflect a combination of isostatic loading and eustatic changes in global sea level c 2005 elsevier ltd all rights reserved

a new technique for the automatic monitoring of erosion and deposition rates the rates and processes of erosion and deposition of soils and sediments are subjects of widespread and increasing concern in the earth and environmental sciences process inference from field studies however has been hampered by a lack of information on the precise magnitude frequency and timing of erosional and depositional activity because no automatic monitoring technique has hitherto been available i describe here an automatic photo electronic erosion pin peep system which apparently for the first time allows quasi continuous time series of erosion and deposition data to be collected example results from a river bank site show how the peep system helps to define the true temporal distribution of geomorphological change quantify the erosional impact of individual forcing events and discriminate between competing hypotheses of process control in erosional and depositional contexts the system should thus allow more effective testing of erosion models of high temporal resolution and facilitate a more rigorous linking of catchment sediment output to supply dynamics

combined organic and inorganic geochemical reconstruction of paleodepositional conditions of a pliocene sapropel from the eastern mediterranean sea layers of organic carbon rich sapropels in the sediment record of the mediterranean sea give evidence of repetitive changes in regional plio pleistocene climate results from biomarker molecule and major and trace element analyses of closely spaced samples are used to reconstruct the conditions leading to deposition of a pliocene sapropel at ocean drilling program odp site 969 on the mediterranean ridge organic carbon concentrations increase from 0 2 outside the sapropel and peak to more than 30 within it major and trace elemental composition and biomarker derived parameters indicate elevated productivity depletion of water column dissolved oxygen content and changes in sediment provenance in response to climatic changes budgets of rhenium thallium and other trace metals indicate that deep water exchange between the mediterranean subbasins and the atlantic ocean was not completely interrupted during sapropel formation enrichment factors of redox sensitive and sulfide forming trace metals as well as the presence of isorenieratene derivatives and high stanol sterol ratios point to an extended zone of anoxic water masses depth profiles of biomarker compositions sterols long chain alkenones alkandiols and ketols fatty acids indicate great floral diversity during deposition of a single sapropel and highlight the sensitive response of the marine community to variable environmental conditions changes in water mass circulation and eolian transport can be reconstructed by use of both lithogenic elements and average chain lengths of n alkanes acl index

peroxide concentrations in the dome summit south ice core law dome antarctica measurements of h2o2 concentrations have been made at intervals along the full length of the dome summit south dss ice core from law dome antarctica these results show mean peroxide concentrations of approximately 37 parts per billion by mass over the past 4 kyr and a tendency for concentrations to decrease with age the rate of h2o2 decay in antarctic ice appears slower than in greenland ice and the pattern of measurements suggests an abrupt increase in concentration during the emergence from the last glacial into the holocene there is some evidence for a recent increase in h2o2 but the data so far are not conclusive detailed examination of the timing of the seasonality in h2o2 and 18o shows that peroxide extrema occur very near the solstices these seasonal curves have been used to derive atmospheric seasonal h2o2 curves based on possible air snow partitioning models these show a broad low in atmospheric concentration with a sharp peak which is again very near the summer solstice

sea level change in the irish sea since the last glacial maximum constraints from isostatic modelling models of glacio hydroisostatic sea level change have been published for the british isles that are broadly consistent with the observational evidence as well as with glaciological constraints it has been argued however that the models fail to represent sea level change along the irish sea margins and in southern ireland for the post deglaciation period the argument rests on the interpretation of the depositional environment of the elevated irish sea drift on both sides of the irish sea whether this is terrestrial or glaciomarine the isostatic models for the british isles are consistent with the former interpretation in that sea levels on either side of the irish sea south of about the isle of man are not predicted to have risen above present sea level at any time since the deglaciation of the irish sea this implies that ice over both the irish sea and ireland was relatively thin ca 600 700 m over ireland if the glaciomarine interpretation of the elevated irish sea drift is correct then the maximum ice thickness over central and southern ireland would have to reach 2000 m exceeding that over scotland furthermore for the resulting sea level change to be consistent with the holocene evidence this thick ice sheet could not have extended to the eastern side of the irish sea nor could it have been very thick at its northern and western limits if such an ice model is extreme and incompatible with glaciological observations then the alternative is to accept the interpretation of the irish sea drift as terrestrial in origin copyright 2001 john wiley sons ltd

bluff response to wave action abstract the unconsolidated materials forming the bluffs along the coasts of the great lakes are subject to active wave erosion which results in losses in millions of dollars annually due to property damage and reduction in property values an understanding of the mechanics of bluff recession and the long term trends in the evolution of coastal bluffs is required for an evaluation of engineering and management solutions for the problems created by retreating coastal bluffs bluff retreat is usually analyzed and measured from airphotos however since airphotos are taken at discrete points in time they are not capable of providing a full account of bluff retreat mechanisms field investigations coupled with analytical methods can enable investigators to identify patterns of bluff retreat these patterns subsequently incorporated into slope evolution models shed light on data obtained over long periods from airphotos the present paper explains recession rates and bluff profile changes as measured from airphotos with the help of bluff evolution models already established for the bluffs forming the great lakes shorelines

toe erosion of glacial till bluffs lake erie south shore toe erosion and rates of recession of the toe were measured at four sites along a 3 5 km long stretch of shoreline on the south shore of lake erie from april to december 1986 the shoreline consists of bluffs ranging from 5 to 12 m in height and developed in overconsolidated till toe erosion was measured at peg lines consisting of pins driven horizontally into the face of the bluff at 0 25 m intervals to a height of 1 75 m above the beach and steel rods driven vertically into the beach with a spacing of 1 5 m at each site three lines were established and monitored at 1 2 week intervals because of record high lake levels beaches in front of the bluffs were generally 5 m wide and some erosion was measured on all but three occasions recession of the toe during any measurement period was generally 2 6 cm with the maximum recorded being about 12 cm wave action during high magnitude storms resulted in erosion occurring much higher up the bluff face than for low magnitude events but the actual recession of the toe was not substantially greater a multiple regression model shows that there is a significant relationship between toe recession and several variables that indirectly control wave energy at the bluff toe however factors such as beach width and thickness of beach sediment did not have a significant influence on recession rates in this study likely because the high lake levels resulted in very narrow beaches at all four sites throughout the study period