recent and pleistocene beach dune sequences western australia abstract wave dominated sandy shores occur along much of the coast of western australia despite local variations there is a characteristic distribution of lithofacies corresponding to different geomorphic zones five lithofacies are recognised 1 trough bedded sand gravel 2 laminated sand 3 laminated bubble sand 4 laminated disrupted sand and 5 aeolian cross stratified sand the trough bedded sand gravel lithofacies is being deposited in the shallow shoreface below lwl the laminated sand and laminated bubble sand lithofacies are sands with gravel layers being deposited on the foreshore swash zone extensive bubble or vesicular sand is common towards hwl especially in berms the laminated disrupted sand lithofacies is being deposited on the backshore between hwl and storm water levels and consists of horizontally layered to homogeneous sands with storm debris especially wood weed and floatable skeletons e g sepla and spirula the aeolian cross stratified sand lithofacies is forming in beach ridge dune areas and consists of fine sands with large scale generally landward dipping forests soils and rootlets are common recognition of these lithofacies within a sedimentary sequence enables reconstruction of gross shoreline conditions in terms of wave and eolian environments tidal and storm heights and palaeogeography each of these lithofacies with their characteristic features is recognised in pleistocene sequences in perth basin the pleistocene sequences fit a model of coastal progradation with the trough bedded sand gravel lithofacies at the base and the aeolian sand lithofacies at the top the value of such a stratigraphic sequence however extends beyond the pleistocene

the geomorphologic evolution of the wilderness dune cordons south africa abstract the wilderness dune cordons consist of steep sided ridges up to 207 m high separated by coastal lakes they probably formed during the sea level highstands of the pleistocene interglacials three major dune cordons are developed there is an additional huge coalesced mass of older fossil dunes landward of these cordons forming hills up to 340 m high in places lying on the coastal platform 150 260 m generally locally 210 260 m the dunesand reaches thicknesses in excess of 300 m the cordons form by accretion of transgressive dunefields and large compound imbricate parabolic dunes an individual cordon can result from numerous phases of dune formation during periods of sea level highstand the dunes of the present interglacial are mostly accreting on top of the seaward cordon which was initiated during the last interglacial during the complex sea level history there have been numerous phases of dune building followed by coastal erosion that formed seacliffs in the dune cordons in some areas almost all the cordon was subsequently eroded away these fossil seacliffs form large steep seaward facing slopes parallel to the present coastline and form a major element in the morphology of the cordons trailing arms of parabolic dunes form another major topographic element oriented at 15 30 to the shoreline river erosion has altered the cordon morphology in places the geomorphology of the cordons is thus a function primarily of dune cordon construction accentuated by coastal erosion in the form of cliff cutting secondarily of dune morphology and thirdly of fluvial erosion the evolution of the cordons can be dated tentatively using palaeontologic stratigraphic and sediment dynamic data the seaward cordon formed during the eem and holocene a fairly reliable dating the middle cordon probably formed between 200 500 ka and the landward cordon probably formed between 600 900 ka the coalesced dune deposits lie inland of the cordons and are thus older this would place the minimum age of the younger coalesced dune deposits in the middle pleistocene about 1000 ka early miocene fossil plant remains in the knysna lignites which underlie the older coalesced dunes indicate their maximum possible age westerly winds dominated in the area for the past few million years

indosinian dextral ductile fault system and synkinematic plutonism in the southwest of the ogcheon belt south korea reply abstract the structure of the mylonite belt in the southwestern part of the ogcheon belt has been investigated and interpreted in the light of recent radiometric data the shear belt is composed of several en echelon dextral shear zones relayed by compressional or extensional tectonic bridges the dextral displacement along the fault system which may be extended to the hida zone of japan is of the order of 200 km it has brought into contact the ryeongnam block and its cambrian middle ordovician cover of north china affinity with the southwestern margin of the ogcheon belt characterized by cambrian middle silurian rift facies and shelf deposits of south china affinity synkinematic plutons are emplaced within the shear belt which is postdated by uppermost triassic unfoliated granitoids at the surface the shear belt generated elongated intermontane coal basins initiated as transtensional half grabens because of its post permian pre early jurassic age and its dextral kinematics we correlate the shear belt with the late stages of the akyioshi indosinian collisional orogeny of the east asian margin the synkinematic plutonism that accompanied the shear zone may be due to post collisional crustal stretching and subsequent anatexis at the mantle crust interface

wave beach and dune interactions in southeastern australia abstract a morphodynamic classification of surfzones beaches and dunes of the microtidal low to high energy southeast australian coast is presented the first section a waves and beaches briefly deals with the transformation of deep water wave energy as it crosses the shelf nearshore and surfzone depending on the deep water wave characteristics and shelf and inshore morphology resultant breaker wave energy may be high moderate or low and the accompanying beach surfzone morphodynamic state in fine to medium sand beaches either dissipative intermediate or reflective dissipative beaches have wide surfzones with shore parallel bar s and channel s and predominantly shore normal circulation intermediate beaches are characterised by rip circulation crescentic transverse bars and megacusps and reflective beaches by a barless surfzone and steep cusped or bermed beach each beach form has a characteristic level of beach stability zone of sediment storage and mode of beach and dune erosion landward aeolian sediment transport of swash deposited sand section b is dependent on the subaerial beach topography and the aerodynamic flow regime across that topography characteristic profile shapes are ascribed to each beach type dissipative intermediate and reflective aeolian sand transport rates are potentially highest on dissipative beaches moderate on intermediate beaches and lowest on reflective beaches these rates determine the potential size of foredunes which are correspondingly largest on dissipative beaches and smallest on reflective beaches the combination of mode and frequency of beach dune erosion rates of aeolian sand transport and foredune volume and morphology provide an explanation of the nature and morphology of landward occurring large scale dune systems dissipative beaches are frequently characterised by large scale transgressive dune sheets intermediate by a trend from large scale parabolic dune systems high wave energy to small scale blowouts low wave energy and reflective beaches by minimal dune development

the vertical thermohaline structure in the argentine basin the vertical thermohaline structure in the central argentine basin is investigated on the basis of high resolution hydrographic data emphasis is placed on fronts their horizontal gradients vertical stability and associated fine structure horizontal thermohaline gradients vary strongly with depth regions of strong gradients alternating with those of weak gradients the strongest gradients occur often at depths below the upper mixed layer the salinity gradient maximum occurs above the temperature gradient maximum enhanced gradients are found where warm salty water moves over cooler fresher water such as between the subtropical water stw and antarctic intermediate water aaiw and between the north atlantic deep water nadw and the antarctic bottom water aabw temperature salinity and density fronts do not always coexist density compensating temperature and salinity fronts occur in the surface layer of the subantarctic and at abyssal depth below 3500 m vertical profiles of the vaisala frequency indicate much reduced hydrostatic stabilities in the brazil current and subantarctic frontal zones potential vorticity minima indicate the formation of subantarctic mode water just north of the subantarctic front and its subsequent northward and upward spread across isopycnals the thermohaline fine structure is vertically intermittent the amplitude variances between the enhanced and quiet regions vary by almost 2 orders of magnitude enhanced fine structure amplitudes are found near the stw aaiw and nadw aabw interfaces where large horizontal thermohaline gradients occur and the hydrostatic stability is low the temperature and salinity fine structures are largely density compensating the coherence between the temperature and salinity fine structure is strongly depth dependent and is highest in regions where warm salty water moves over cooler fresher water

holocene coastal dune formation in southern australia a case study abstract the 14 500 km long southern australian coast is exposed to high energy wave and wind regimes which have mobilized shelf derived sediments to produce extensive holocene shoreface deposits the 8000 km of sandy coast are backed by over 2000 km 2 of holocene dunes of varying degrees of stability in places dune deposition above present sea level accompanied the post glacial marine transgression commencing as early as 10 ka b p and has continued episodically to the present day the dunes are widespread in extent but vary in type size and evolution the oldest and often most extensive primary dune fields accompanied the post glacial marine transgression they occurred and in some places continue to form in areas of high wave and wind energy and abundant sand supply many of these systems exhausted their sediment supply by mid holocene and remain as stranded clifftop dunes where sand ramps were eroded or as eroding barriers secondary phases of dune activity occurred on moderate to high energy coasts following an initial period of post stillstand barrier progradation diminished sediment supply resulted in shoreline erosion and secondary dune formation the location size and evolution both of dunes types is largely controlled by the breaker wave regime which in turn influences the rate and volume of sediment supply beach morphodynamics and resulting aerodynamic boundary conditions and foredune erosion a study of dune formation along the 3700 km long south australian coast provides a basis for an overview of dune formation throughout southern australia

coastal environmental changes associated with holocene sea level fluctuation southeastern buenos aires argentina abstract sea level was 2 m higher than present 6000 years ago at southeastern buenos aires province argentina this fluctuation has caused several environmental changes including drift reversal geomorphological features and radiocarbon dating suggest that the mar chiquita barrier grew from north to south during the regression from 4000 years bp in contrast mineral dispersals coastal defenses inlet migrations and wave statistics show that present beach drift is to the north in the same direction as storm induced shelf sediment transport coastal mollusk mass mortalities lagoonal deposits that accumulated during the regression contain abundant remains of mactra isabelleana tagelus plebeius and labiosa plicatella these species are rare in present coastal lagoons many causes have been proposed for the absence of these species in present lagoons and include sudden sea level decline outlet obstruction producing variation in salinity and increased fluvial freshwater inputs the regional character of these mortalities and growth curves indicates that taphonomic feedback processes related to the scarce 2 m involved in the transgressive regressive cycle are the reason for mollusk mortality sand consumption during the latter stages of the holocene transgression sand ramps up to 10 m height at mar del plata cliffs and sand barriers up to 2 km width north of mar chiquita village developed as a result of high wave energy and a plentiful sand supply the subsequent regressive phase produced lagoons tidal flats marshes and cheniers the alongshore growth of barriers meaned their cannibalization misfit foredunes and narrowing driftwards these processes occurred before the drift reversal mentioned above

pleistocene and holocene beaches and estuaries along the southern barrier of buenos aires argentina abstract the buenos aires aggradation plain has a good record of quaternary sea level fluctuations to the east of the tandilia range the elevations of the pleistocene beaches respond to the tectonic behaviour of the salado basin holocene beaches indicate a maximum transgression higher than 2 m the low relief permitted an extended horizontal record of beach chenier plains interfingered with estuarine environments coastal lagoons marshes covered by a sandy eastern barrier between the tandilia and ventania ranges the location of pleistocene and holocene beaches are related to a former higher relief i e they are attached to low altitude cliffs and underneath cliff top dunes composing the southern barrier at claromeco pleistocene gravel beaches mostly composed of caliche pebbles occur at heights between 4 and 7 m and are overlying estuarine pleistocene environments beaches of the same age are at a level of 10 m at mar del plata harbour and arroyo sotelo west of mar chiquita lagoon holocene beaches found at punta mogotes and costa bonita are at higher altitudes than on the eastern barrier ca 2 4 m the holocene estuarine sequences are related laterally to present operating inlets las brusquitas la ballenera quequen grande claromeco quequen salado they are seldon thicker than 2 4 m and comprise basal layers of black muds towards the top the layers are thinner of coarser grain size and white colours grain size analyses were performed comparatively on pleistocene mid holocene and present beaches sangamonian beaches aregravelly or coarser than medium sand mean holocene beaches are usually coarser than medium sand but dominantly shelly to the north of mar del plata and composed of volcanic clasts to the south of this city modern beaches are dominated by fine sand except at some erosive beaches between the mar del plata capes they have a lesser content of shells than those of mid holocene

plasmaspheric drainage plume observed by the polar satellite in the prenoon sector and the image satellite during the magnetic storm of 11 april 2001 1 during the early main phase of a geomagnetic storm on 11 april 2001 the polar satellite was inside the magnetosphere in the prenoon sector 1000 1100 magnetic local times and experienced a magnetopause crossing at l 6 because of the high solar wind dynamic pressure and strong southward interplanetary magnetic field imf just before the magnetopause crossing polar observed cold dense plasma that is the cold dense plasma was immediately adjacent to the compressed magnetopause using simultaneous observations by the image extreme ultraviolet euv imager we confirm that the cold dense plasma observed by polar is a plasmaspheric drainage plume extending outward from the plasmasphere to the magnetopause during the interval of high geomagnetic activity and strong southward imf we compare plasmaspheric mass densities determined from ground magnetometer data at l 2 3 and 2 9 for a magnetically quiet time interval to mass densities determined during the magnetic storm time interval we find no significant differences in the mass density between both intervals these observations suggest that the sunward convecting plasmaspheric plasma observed at polar is due to erosion of the outer layers of the plasmasphere beyond l 2 9

effect of plasmaspheric drainage plumes on solar wind magnetosphere coupling evidence is uncovered that plasmaspheric drainage plumes flowing into the dayside reconnection site mass load the reconnection rate and thereby reduce the coupling of the solar wind to the earth s magnetosphere solar wind magnetosphere coupling is statistically analyzed with the 1963 2003 omni2 data set matched up with the ae au and pci geomagnetic indices times when plasmaspheric drainage plumes are flowing are discerned using multiple spacecraft with plasma detectors in geosynchronous orbit it is found that for a given value of vbz of the solar wind the geomagnetic indices ae au and pci are statistically lower when plasmaspheric drainage plumes are present than when plumes are not present this is taken as a measure of a weakened coupling of the solar wind to the earth s magnetosphere caused by the plumes an addendum examines the effects of polar cap saturation on the auroral electrojet index

mass mortality of a holocenetagelus plebeius mollusca bivalvia population in the bahia blanca estuary argentina abstract a mass mortality phenomenon affecting a mollusc fauna on the holocene tidal flat of the bahia blanca estuary is analyzed specimens oftagelus plebeius are located in a well defined horizon with both valves articulated and in life position the mass mortality of thetagelus plebeius population is a consequence of its catastrophic burial by sandy sediment of fluvial origin

late quaternary evolution of coastal sand barriers port stephens myall lakes area central new south wales australia abstract the geomorphic and stratigraphic history of six coastal embayments has been studied in the vicinity of newcastle new south wales n s w australia in order to determine modes of deposition and the degree to which marine and estuarine deposits can be correlated and dated each embayment possesses its own distinctive suite of landforms ranging from those dominated by coastal dunes to those in which beach ridges occur in four of the bays dual sand barriers comprising an inner barrier and an outer barrier provide the framework for correlation between embayments six stages are recognized in the deposition of late quaternary sediments in this area i pre last interglacial involving accumulation of separate composite units consisting of estuarine clays and transgressive dune complexes ii last interglacial stage during which inner barriers were formed iii last glacial reworking of barrier and dune sands by westerly winds iv postglacial marine transgression during which the outer barriers were initiated v mid holocene stage following cessation of sea level rise ca 6000 6500 yr b p on this coast and involving progradation of outer barriers in some embayments and vi late holocene episodic eolian reworking of dune complexes and outer barriers the relatively high wave and wind energy as well as the tectonic setting of the central n s w coast results in somewhat different geomorphic histories from barrier island coasts in north america and europe

late palaeozoic to early mesozoic geodynamic evolution of the circum pacific orogenic belt in south korea and southwest japan abstract a review of the overall features of the late palaeozoic early mesozoic orogen of southwest japan and its korean hinterland allows a new geodynamic model for the building of the east asian margin to be proposed during middle carboniferous to early permian times an oceanic basin formed in a passive margin environment at a moderate spreading rate as the honshu continental block drifted away from the sino korean continent during that period paralic platform conditions and extensional synsedimentary tectonics prevailed in korea in middle permian times the closure of the oceanic area was responsible for yakuno ophiolite obduction and high pressure metamorphism while highly subsiding coal basins developed in the emerged korean hinterland thereafter in late permian times when the honshu block collided with the asian margin akiyoshi orogeny locally derived terrestrial clastic sedimentation in korea has succeeded coal measure deposition with local unconformity in early triassic times the collision was completed and regional uplift of the thickened crust resulted in the deposition of thick distal siliciclastic rocks in rapidly subsiding hinterland troughs korea and flyschoid deposition in the tamba foreland basin outer zone of southwest japan middle to late triassic medium to low pressure metamorphism large scale transcurrent tectonics and associated calc alkaline synkinematic plutonism in the hida and ogcheon belts represent a post collisional feature of the akiyoshi orogenic event post tectonic intrusives and terrestrial deposits post date intracratonic tectonics at ca 200 ma thus the akiyoshi orogeny of southwest japan is a result of continental drift and ensuing collisional rewelding of a fragment of sino korea the honshu microcontinent

relationship between shear zones and sr isotope compositions of granitic rocks in the hida belt japan the dextral shear zones in the hida belt central japan show close temporal and spatial relationships with some of the late triassic to early jurassic funatsu granitic intrusions the sr isotopic compositions of intrusions associated with the shear zones suggest large crustal contributions to the magma chemistries in contrast granitic intrusions not accompanied by shear zones show less crustal signatures various models could possibly explain the genetic relationship between shear zones and granitic magmas with crustal isotope characteristics though it is not clear which model is most applicable it is suggested that contrasting characteristics in the two types of intrusions reflect different stress conditions the granitic rocks without large crustal contributions are likely to be the products of extensional stress conditions those with a larger amount of crustal contamination seem to be generated in compressional stress situations that accompanied the development of ductile shear zones along the co

crustal development of the hida belt japan evidence from nd sr isotopic and chemical characteristics of igneous and metamorphic rocks abstract chemical and sr nd isotopic investigations were performed on the igneous and metamorphic rocks in the hida belt central japan to clarify their ages and possible sources and to provide constraints on the crustal evolution of the eastern margin of the asian continent igneous rocks of three main stages in the hida belt represented by the late silurian amphibolites first stage the middle carboniferous mafic dikes second stage and the late triassic to early jurassic granite gabbro plutons third stage show alkaline to calc alkaline chemical affinity major and trace element characteristics show that the three stages of igneous rocks were emplaced in a continental margin or continental arc environment the mafic igneous rock suites have relatively high e nd 0 5 to 5 5 and low 87 sr 86 sr 0 7049 to 0 7061 values indicating their origin from upper mantle sources though the third stage granitoids contain recycled crustal components the hida gneisses of clastic origin show two groups of model ages t dm middle proterozoic 1 4 2 2 ga and late proterozoic to early paleozoic 0 55 0 74 ga consistent with geological geochemical and radiometric age data are that the sedimentation and basaltic volcanism occurred in early to middle paleozoic and the protoliths with middle proterozoic model ages are detritals from the proterozoic continental provenances a synthesis of available geological and geochemical data for the basement metamorphic and igneous rocks in eastern asia suggests two possibilities for the paleozoic to early mesozoic history of the hida belt 1 the hida belt was formed at the eastern margin of the north china block with later evolution as a suture zone between the north and south china blocks or 2 it evolved as a part of the east central asian orogenic belt ecaob to the north

direct observations of the role of convection electric field in the formation of a polar tongue of ionization from storm enhanced density 1 we examine the relationship of convection electric fields to the formation of a polar cap tongue of ionization toi from midlatitude plumes of storm enhanced density sed observations from the geomagnetic storm on 26 27 september 2011 are presented for two distinct sed events during an hour long period of geomagnetic activity driven by a coronal mass ejection a channel of high density f region plasma was transported from the dayside subauroral ionosphere and into the polar cap by enhanced convection electric fields extending to middle latitudes this toi feature was associated with enhanced hf backscatter indicating that it was the seat of active formation of small scale irregularities after the solar wind interplanetary magnetic field conditions quieted and the dayside convection electric fields retreated to higher latitudes an sed plume was observed extending to but not entering the dayside cusp region this prominent feature in the distribution of total electron content tec persisted for several hours and elongated in magnetic local time with the rotation of the earth no ionospheric scatter from superdarn radars was observed within this sed region the source mechanism enhanced electric fields previously drawing the plasma from midlatitudes and into the polar cap as a toi was no longer active resulting in a fossil feature we thus demonstrate the controlling role exercised by the convection electric field in generating a toi from midlatitude sed

palaeoenvironmental evolution and sea level fluctuations along the southeastern pampa grasslands coast of argentina during the holocene holocene pollen and diatom analyses and complementary data from 18o and 13c malacology and sedimentology have provided a detailed record of vegetation history and palaeoenvironmental change at arroyo las brusquitas on the southeastern coast of the pampas of argentina especially in relation to past sea levels holocene palaeosalinity trends were estimated by detrended correspondence analysis and by salinity indexes based on pollen and diatom data as a consequence of sea level rise from the postglacial an extensive wave cut platform formed over which holocene infilling sequences were deposited unconformably in these sequences variation in pollen and diatom assemblages occurred in agreement with changes in mollusc diversity and abundance isotope values and sediment deposits between ca 6700 and 6190 14c yr bp 6279 6998 cal yr bp saline conditions predominated in an environment highly influenced by tides and salt water during the holocene sea level highstand between ca 6200 and 3900 14c yr bp 4235 4608 cal yr bp shallow brackish water bodies formed surrounded by saltmarsh vegetation that became more widespread from 5180 14c yr bp 5830 6173 cal yr bp to 3900 14c yr bp in relation to a sea level stabilisation period within the regression phase less saline conditions marked by frequent variations in salinity predominated between ca 3900 and 2040 yr 14c bp 1830 2160 cal yr bp the intertidal saltmarsh environment changed into a brackish marsh dominated by freshwater conditions and sporadic tidal influence halophytic vegetation increased towards ca 200014c yr bp indicating that saline conditions may be due to either desiccation or an unusually high tide range with rare frequency after ca 2000 14c yr bp the sedimentary sequences were buried by aeolian sand dunes changes in holocene vegetation and environments in las brusquitas area are in agreement with data obtained from various southeastern coastal sites of the pampa grasslands copyright 2005 john wiley sons ltd

beach and nearshore facies southeast australia abstract the morphology texture and facies sequence on seven sand beaches located in low moderate and high wave energy microtidal environments in southern australia were investigated using box coring and scuba observations systematic variation in facies occur both within and between the beaches low energy reflective beaches are limited in lateral and vertical extent and in facies to beach laminations separated by coarse step deposits from finer nearshore cross lamination facies moderate energy intermediate beaches characterised by rip circulation possess increasingly wider surfzones with ridge and runnel and bar trough facies separating the beach and step facies from the more extensive nearshore sequence high energy dissipative beaches may have 500 m wide surfzones containing multiple bar trough topography fine beach laminations with backwash structures grade into 4 5 m thick bar trough sequences then the extensive nearshore facies as wave energy increases from low h b h b 2 5 m the vertical extent of the beach to nearshore sequence increases from

global plasmasphere evolution 22 23 april 2001 1 the evolution of the plasmasphere during the moderate 22 23 april 2001 storm is studied by comparing observed plasmasphere behavior to the predictions of a simulation the plasmasphere observations include global images from image euv and density and flow measurements from lanl mpa the subjective uncertainty in the euv plasmapause was found to be 0 2l inward plasmapause motion was correlated with southward interplanetary magnetic field imf with a 27 min delay the electric e field at the plasmapause was approximately 13 of the solar wind e field the observations support the idea that plasmaspheric erosion begins with a partial plasmapause indentation which then gradually widens in magnetic local time mlt to encompass the entire nightside in situ measurements confirm a dayside plume of sunward flowing plasma and images show that the plume subsequently experienced phases of mlt narrowing and rotation wrapping to simulate the event we employed a test particle representation of the plasmapause using a parametric e field model that includes corotation and convection from two sources dayside magnetopause reconnection dmr and the subauroral polarization stream saps the model captures the phases of plume evolution and it reproduces the observed plasmapause with maximum mean error 0 7l 0 24l the model fails to reproduce important subglobal features e g a predawn plasmaspheric shoulder and grossly misplaces the inner edge of the rotating and wrapping plume saps contributes significantly to the duskside flows but the simulated flows are about 50 smaller than those seen by lanl mpa the simulated plasmapause e field is about 70 of the euv inferred value

long lived plasmaspheric drainage plumes where does the plasma come from long lived weeks plasmaspheric drainage plumes are explored the long lived plumes occur during long lived high speed stream driven storms spacecraft in geosynchronous orbit see the plumes as dense plasmaspheric plasma advecting sunward toward the dayside magnetopause the older plumes have the same densities and local time widths as younger plumes and like younger plumes they are lumpy in density and they reside in a spatial gap in the electron plasma sheet in sort of a drainage corridor magnetospheric convection simulations indicate that drainage from a filled outer plasmasphere can only supply a plume for 1 5 2 days the question arises for long lived plumes and for any plume older than about 2 days where is the plasma coming from three candidate sources appear promising 1 substorm disruption of the nightside plasmasphere which may transport plasmaspheric plasma outward onto open drift orbits 2 radial transport of plasmaspheric plasma in velocity shear driven instabilities near the duskside plasmapause and 3 an anomalously high upflux of cold ionospheric protons from the tongue of ionization in the dayside ionosphere which may directly supply ionospheric plasma into the plume in the first two cases the plume is drainage of plasma from the magnetosphere in the third case it is not where the plasma in long lived plumes is coming from is a quandary to fix this dilemma further work and probably full scale simulations are needed

holocene sea level fluctuation in the southern hemisphere abstract if rising sea levels dominate in the northern hemisphere nh falling or fluctuating sea levels predominate in the southern hemisphere sh endogenic processes tectonics isostasy or geoidal changes could explain local or regional mean sea level msl fluctuations but not an hemispherical one evidence from south america africa antarctica australia and the pacific and indian oceans suggest that the holocene transgression rose above the present msl in higher latitudes before the tropics by plotting latitude against the age of msl arrival at present coasts good correlation is observed oceanic salinity mixing has been already proposed to explain this mid holocene sea level fluctuation climate could be the only factor responsible for this hemisphere wide behavior of msl it has been suggested previously that the climate of the sh precedes that of the nh by 3000 years the climatic optimum or maximum warmth occurred predominantly about 6000 bp in the nh but about 10 9000 bp in the sh short term climatic effects on the sea level monsoons southern oscillation el nino phenomena should have significant occurrences during the past in the windiest oceanic hemisphere this latitudinal trend in former msl should be considered when using shorelines as reference points for measuring vertical crustal movements

thermohaline fronts and baroclinic flow in the argentine basin during the austral spring of 1984 thermohaline fronts structure and baroclinic flow in the central argentine basin are investigated on the basis of a 1984 field experiment the brazil current after initial overshoot meanders northeastward toward subtropical latitudes with speeds of the order of 0 3 m s 1 the meanders have a wavelength of about 400 km and an amplitude of 200 km brazil current signatures as expressed by dynamic height are recognizable to depths of several kilometers the brazil and antarctic circumpolar currents do not meet in the central argentine basin to form common eastward flow as was expressed in classical descriptions but instead diverge sharply near 42 w this is seen also in the trajectories of satellite tracked drifters the region between the currents is marked by cyclonic and anticyclonic eddies strong thermohaline fronts accompany the boundaries of these currents the brazil current and subantarctic fronts are well separated in the central basin brazil current density fronts are deep and extend from the surface to 3000 m while the associated temperature and salinity fronts are intermittent over this depth interval temperature fronts virtually vanish at the interface between the antarctic intermediate water and the north atlantic deep water salinity fronts reverse their polarity beneath the core of the former at depths between 3000 and 4000 m abyssal temperature and salinity fronts are observed which are largely density compensating at the subantarctic and cold core eddy fronts horizontal temperature and salinity gradients in the upper mixed layer compensate each other in such a way that no density front is found deep subpycnocline mixed layers occur in the poleward lobes of the brazil current during austral spring suggestive of previous winter convection

global response of the plasmasphere to a geomagnetic disturbance 1 global images of the plasmasphere obtained by the extreme ultraviolet euv imager on the image satellite are used to study the evolving structure of the plasmasphere during two geomagnetic disturbances by tracking the location of the plasmapause as a function of l shell and magnetic local time quantitative measurements of radial and azimuthal motions of the boundary are made for intervals 7 hours in duration with a time resolution of 10 min the two cases presented are 26 27 june 2001 a relatively weak but isolated geomagnetic disturbance and 9 10 june 2001 a moderate event with a multistaged onset and recurring substorm activity after the main disturbance in both cases the onset of the disturbance correlated with a southward turning of the imf is characterized by inward motion or erosion of the plasmapause and a smoothing of any existing azimuthal variations across the nightside over a period of many hours a plasmaspheric plume forms in the afternoon sector as a result of sunward flows from dusk and corotational flows across the dayside azimuthal variations in the plasmapause radius tend to form in the local time sector from dawn to the western edge of the plume including mesoscale 0 5 in l and 2 hours in local time crenulations and larger scale shoulder features while the nightside boundary remains featureless in the 26 27 june 2001 case the magnetosphere entered a period of deep quiet after the main disturbance and the plasmaspheric plume began to corotate with the main plasmasphere from the afternoon sector across the nightside in contrast the plume in the 9 10 june 2001 event became wrapped around the main plasmasphere and a second plume formed in the afternoon sector perhaps due to continued substorm activity in situ density data for these events show highly irregular density structure within the plumes as measured at geosynchronous orbit whereas a measurement by image rpi suggests that there may be less structure near the base of the plume closer to the main plasmasphere

ionospheric signatures of plasmaspheric tails 1 we make direct comparisons between gps maps of total electron content tec over the north american continent millstone hill radar observations of storm enhanced density and low and high altitude satellite measurements of the perturbation of the outer plasmasphere during the march 31 2001 geomagnetic storm we find that storm enhanced density sed and plumes of greatly elevated tec are associated with the erosion of the outer plasmasphere by strong sub auroral polarization electric fields the sed tec plumes identified at low altitude map closely onto the magnetospheric determination of the boundaries of the plasmapause and plasmaspheric tail determined by euv imaging from the image spacecraft characteristics of the sed tec plumes tails for the march 31 2001 event are tec 100 tecu f region sunward velocity 1000 m s sunward flux 5 1024 ions s 1 total transport to dayside magnetopause merging region 3 hr event 5 1028 ions

timing and magnitude of holocene sea level changes along the middle and south patagonian atlantic coast derived from beach ridge systems littoral terraces and valley mouth terraces abstract geomorphologic and chronostratigraphic investigations in various coastal localities along the middle and south patagonian atlantic coast from bahia vera 44 s in the north to san julian 49 s in the south confirm a rich sequence of holocene beach ridge systems and littoral and valley mouth terraces beach ridges are present up to 10 m above current highest tide level htw and date to the early mid holocene transgression maximum beach ridge deposits represent high energy wave dominated coastal environments whereas valley mouth terraces and littoral terraces elevations of 5 5 6 5 m above htw developed in wave protected coastal environments the surface elevation of these littoral forms suggest that the middle and south patagonian atlantic coast is likely undergoing a slow glacio isostatic uplift on the order of 0 3 0 4 mm a since the mid holocene the early holocene sea level rise reached the modern coastline by 8100 14 c years ago c 8600 cal bp at the latest sea level at that time was most likely near its present position the holocene transgression maximum lasted from 6900 to at least 6200 14 c bp c 7400 to 6600 cal bp raising relative sea level to about 2 m to a maximum of 3 m above the present level after which sea level declined to the present level two significant sea level falls of at most 1 m occurred a between 6200 and 6000 14 c bp c 6600 to 6400 cal bp and b between 2600 and 2400 14 c bp c 2300 to 2050 cal bp we assume that both significant sea level falls were predominantly driven by eustatic changes of ocean volume whereas both thermo steric changes and changes of tides may also have contributed to these relatively strong sea level drops gravitational changes driven by greenland ice growth sensu mitrovica et al 2001 may also have amplified any eustatic portion of sea level fall the trend of a general sea level decline since the mid holocene transgression maximum seems to be predominantly glacio isostatically driven

statistical analysis of the plasmaspheric plume at the magnetopause 1 during times of enhanced magnetospheric convection cold dense plasma from the plasmasphere can form a plume extending sunward toward the dayside magnetopause a statistical study is presented of cold high density plasmaspheric plasma at the magnetopause observations from the time history of events and macroscale interactions themis spacecraft show the plume to be present at the dayside magnetopause during 12 5 148 of 1184 of the crossings its most common location in magnetic local time when contacting the magnetopause is at 13 6 h the magnetopause crossings show evidence for reconnection in 68 of events with the plume while only 47 of events without plume although the plume is more likely to be observed at the magnetopause when reconnection is occurring the typical reconnection jet velocity is lower for plume events than nonplume events indicating the presence of the plume may be slowing the efficiency of the reconnection process

the stratigraphy of coastal carbonate banks and holocene sea levels of northern spencer gulf south australia abstract stratigraphic and chronologic studies of the coastal sediments of northern spencer gulf in the vicinity of redcliff are described two pleistocene marine units are recognised beneath an extensive holocene peritidal sequence the holocene sequence is dominated by sediments of the posidonia australis seagrass facies which form a distinctive carbonate bank fringing the coastline peritidal sedimentation commenced prior to 6600 radiocarbon yrs b p and a 2 5 m higher relative sea level existed from about 6000 until around 1700 yrs b p the subsequent relative fall to present level probably resulted from local tectonic uplift after the regression mangrove and samphire colonization and beach ridge progradation occurred over the former seagrass bank

quaternary sea levels northern spencer gulf australia abstract five marine transgressions inundated spencer gulf during the late quaternary the oldest encountered deposits are correlated with stage 7 ca 220 ka of the marine oxygen isotope record sediments of the last interglacial maxima mambray formation isotope stage 5e ca 125 ka occupied a gulf of greater lateral extent than the present and sea level reached 1 m above present low water maximum sea levels associated with isotope stages 5c ca 105 ka and 5a ca 82 ka only reached to levels of 8 and 14 m respectively the holocene sea inundated the gulf between 7000 and 8000 yrs b p and subsequently was at least 2 5 m above present level tectonism has had little long term effect on shoreline elevation other than vertical movements of a few metres