karst collapse susceptibility assessment a case study on the amalfi coast southern italy abstract this paper presents a study to evaluate the collapse susceptibility of a karst cave located along a slope on the amalfi coast southern italy and the presumable geomorphological evolution of the whole slope as a result of cave roof collapse in the study area several natural karst caves with volumes varying between 1000 and 10 000 m 3 were inventoried and the most likely genetic processes were identified some of them proved to be remnants of already collapsed caves while others were in precarious stability conditions the caves are usually located upslope or very close to the main populated resorts a detailed geological geomorphological and geostructural study was performed on a very wide deep cave called the saraceno cave on which the resort town of conca de marini has been built the study was carried out through a multidisciplinary approach which included classical field geological observations sometimes requiring the support of rock climbing geologists experts in photogrammetric surveys and terrestrial laser scanning techniques tls tls surveys allowed the reconstruction of an accurate geometric and geostructural model of the cave and its relationship with the upslope conca de marini resort furthermore it allowed the thickness of the cave overburden to be determined in detail ground surfaces most susceptible to collapse were also identified in the event of possible widespread collapse several buildings and transportation infrastructures could be involved as the cave is located on a very steep slope a debris avalanche could be triggered in the event of a catastrophic failure and the landslide debris characterized by a presumably high magnitude and velocity could involve a wide slope area down to the coast the failure evolution could be very similar to that which took place in amalfi in the late 19th century

genesis of the late eocene bedded halite in the qaidam basin and its implication for paleoclimate in east asia abstract it has long been suggested that the eocene climate in east asia was characterized by three latitudinally distributed zones one middle arid zone and two humid zones to its north and south the middle arid zone was firstly proposed based on the widespread red beds and evaporites in a nww trending zone of china however this long standing model has recently been challenged by increasing doubts about the effectiveness of these arid climate indicators the qaidam basin as one of the eocene evaporites bearing basins in china can be studied to test whether the bedded evaporites can validly indicate arid climate over 300 m halite beds have been found in the late eocene upper xiaganchaigou uxg formation in a local saline center shizigou area of the qaidam basin its coexistence with source rocks and limited distribution together with the absence of red beds make it difficult to explain the halite genesis with the conventional climatic controlled playa model based on stratigraphic correlation lithological and mineralogical observation and oxygen carbon and chlorine isotopic analysis we identify several characteristics about the shizigou saline center 1 undulated lake floor 2 shallow water 3 limited hydrothermal impact 4 evaporation induced precipitation 5 high eolian influence and 6 fluctuated climate background according to these investigations we suggest a new model for the genesis of the bedded halite in the qaidam basin the tectonic climatic model the key point for this model is that the undulated topography caused by tectonic activity and the fluctuated climate together leaded to the hydrological isolation of the shizigou area the shizigou area was isolated from the larger brackish qaidam paleolake for independent evaporation during arid climate stage while connected with it during humid climate stage causing alternatively water influx and evaporation and inducing the occurrence of interbedded halite and source rocks thus the widespread bedded halite in the eocene strata over china may indicate fluctuated rather than arid climate in east asia

reconstruction of the upper cretaceous chalks removed by dissolution during the cenozoic in the western paris basin during the cenozoic in the western paris basin atmospheric weathering of the chalks with flints of the upper cretaceous led to the creation of clay with flints a reconstitution of the chalks lost to dissolution is proposed and is based on the determination of the age of the parent chalks of the clay with flints and the quantification of the thickness of dissolved chalk the chalks affected by weathering range in age from turonian to maastrichtian thus confirming the deposition of calcareous sediments in the western paris basin up to the maastrichtian chalk weathering took place in situ as indicated by the preservation of the stratigraphic succession of the chalk in the clay with flints profiles weathering led to the dissolution of 20 200 m of chalk with regional variations the weathering rate varies between 2 1 and 14 5 m ma

age and origin of clayey silt brickearth in west london england the loamy brickearth deposits overlying coarse cold climate kempton park lynch hill and taplow gravels of the r thames in west london are dated by thermoluminescence and mineralogical comparisons with loesses of three known ages although much of the brickearth resembles loess it often contains more sand or clay than typical loess and the mineralogical studies suggest that even the coarse silt 16 63 m fraction is rarely similar in composition to any known english loess the thermoluminescence measurements suggest that most of the brickearth on the taplow and lynch hill gravels was deposited in the late devensian whereas that on the park gravel is mainly flandrian it is suggested that the latter is mainly floodloam whereas the earlier brickearth is a mixed aeolian sediment derived from various local sources in and close to the thames valley

river terrace systems in north west europe an archive of environmental change uplift and early human occupation abstract staircases of large scale aggradational river terraces are a notable feature of many valleys in the temperate lattitudes particularly in areas beyond the reach of the erosive activities of pleistocene ice sheets it is now recognized that the cyclic fluctuations of climate during the quaternary have driven the generation of terraces through the direct and indirect influence of both temperature and precipitation on fluviatile activity where fossiliferous deposits are preserved within terrace sequences it is often possible to date these and to correlate them with the oceanic record thus providing an important framework for the evidence of environmental change on land middle and late pleistocene terraces in different areas can commonly be seen to have formed in synchrony with glacial interglacial cycles or with longer periodicity megacycles climatic forcing alone is insufficient to cause terraces to form however uplift is also necessary so that terrace sequences can provide a useful record of crustal movement in northwest europe where some of the best known studies of river terrace sequences have been carried out the fluviatile deposits are also an important repository for palaeolithic artefacts from which a record of early human occupation can be reconstructed

paleogeographic reconstruction of the eocene idaho river north american cordillera eocene lake gosiute in southwestern wyo ming was progressively fi lled in by volcani clastic sediment between 49 6 and 47 0 ma the source of this material has long been thought to have been the absaroka volcanic province immediately north of the greater green river basin lead isotope compositions of sandstone from this interval however are consistent with derivation from the challis volcanic fi eld the 40 ar 39 ar ages of single de trital k feldspar crystals from greater green river basin sandstones are nearly identical to 40 ar 39 ar eruptive ages for volcanic rocks of the challis volcanic fi eld 49 8 45 5 ma but we also identify mesozoic and proterozoic crystals that are consistent with cooling ages for rocks that were likely exposed in the idaho segment of the north american cordillera during the eocene most of these rocks are traversed by or are up gradient of a major eocene paleovalley in central idaho the sud den appearance of challis derived sediment in the greater green river basin indicates that a major river here named the idaho river connected the interior of the north american cordillera to the greater green river basin this connection requires 500 km to reach from central idaho to the greater green river ba sin the idaho river probably carried detritus that was stripped from distant uplifted moun tains above the active challis volcanic fi eld as far south as the piceance creek basin suggest ing a total length of at least 1000 km middle eocene metamorphic core complexes in the northern cordillera likely produced a major highland in the headwaters of the idaho river which generated river systems that drained both eastward into the wyoming foreland and westward into the oregon coast ranges

the loess and coversands of northern france and southern england loess and coversands are widespread on either side of the english channel in southern england loess is generally thin and discontinuous but locally reaches thickness of about 4 m in east kent coversands occur mainly in areas well north of the channel such as parts of east anglia and the southern side of the bristol channel most of the loess and coversand deposits in southern england date from the late devensian cold stage marine oxygen isotope stage mois 2 but there are also a few localised patches of older mainly mois 6 and 12 loess which are the dissected remnants of originally more extensive covers in france loess is widespread and locally very thick up to 12 m especially in northern and northeastern france in normandy and in the somme basin some long records indicate that accumulation began at the end of the lower pleistocene at about 900 ka nevertheless the main accumulations of typical calcareous loess are related to the upper weichselian and upper saalian stages mois 2 and end of mois 3 and mois 6 indeed before about 160 170 ka loess deposition was generally restricted to special sediment traps such as fluvial and marine terraces exposed to the east or northeast these older deposits are characterised by more sandy facies derived from local fluvial sources mainly by northwest to north northwest winds coversands occur locally along the coast of the mont saint michel bay and over the northern part of the seine estuary near le havre the main differences in thickness and extent of the loess deposits between southern england and northern france are linked to their location in relation to the source areas channel and north sea to ice sheets and to the main wind directions northwest to north northwest in france and western england but northeast in eastern england copyright 2003 john wiley sons ltd

a re examination of the evidence for a plio pleistocene marine transgression on the chiltern hills iii deposits a petrological re examination of the deposits that wooldridge and linton used as evidence for a plio pleistocene marine transgression on the chiltern hills indicates that many are fluvial and some have been reworked in a periglacial climate however those from little heath and rothamsted hertfordshire and lane end buckinghamshire are confirmed as marine and plio pleistocene subsidence during the pleistocene is suggested by the northeasterly decline in height of the few truly marine deposits

sequence stratigraphy in lacustrine basins a model for part of the green river formation eocene southwest uinta basin utah u s a abstract in the middle green river formation of central nine mile canyon uinta basin utah several lacustrine dominated intervals 10 m thick comprise aggradational carbonate parasequence sets and a progradational clastic parasequence maximum flooding surfaces are best identified within profundal oil shale that caps some of the clastic parasequences these lacustrine transgressive systems tracts therefore exhibit parasequence stacking patterns unlike typical marine sequences two types of sequence boundary are identified type a sequence boundaries display evidence for a basinward shift in facies across a regionally mappable surface that is an angular or rarely parallel unconformity and they typically juxtapose amalgamated braided fluvial channel sandstone late lowstand systems tract onto the profundal oil shale they also bound depositional sequences that show a distinct asymmetry being dominated by transgressive systems tracts 5 80 m thick highstand systems tracts are less than 4 m thick and may be removed completely by erosion on overlying sequence boundaries other surfaces satisfy only some of the standard criteria of sequence boundaries and are termed type b sequence boundaries type a sequence boundaries mark pronounced base level falls following times when the uinta lake had merged with a lake in an adjacent basin to form a much deeper lake such merging permitted the establishment of a new threshold at higher elevation following lake level balancing type b sequence boundaries are interpreted as marking base level falls from a barely merged lake or a lake that had an outflow over a 200 m stratigraphic thickness type a sequence boundaries are more common upsection indicating that with time a pluvial climate became more pronounced or that the adjacent lake was more easily filled type a sequence boundaries also become angular rather than parallel unconformities upsection suggesting increased tilting of the basin margin over time

cenozoic postrift domal uplift of north atlantic margins an asthenospheric diapirism model postrift domal uplifts are a distinct feature of the northern north atlantic rifted margins uplifted regions southern norway finnmark svalbard northern united kingdom occur with a typical spacing of 900 km the amount of domal uplift is substantial 1 2 km thermochronological geomorphological and seismic stratigraphic data suggest a coincident neogene onset of uplift postdating north atlantic breakup and predating onset of glaciation the norwegian domes are characterized by strongly negative gravity anomalies and reduced mantle p wave and s wave velocities previous models for uplift around the north atlantic e g glacial erosion intraplate stresses secondary convection fail to explain the above characteristics we present an asthenospheric diapir model based on a rayleigh taylor instability wherein a hot icelandic asthenosphere layer meets cold cratonic lithosphere the generated asthenospheric diapirs and associated partial melting offer a viable explanation for updoming application of this model to the south norwegian dome succesfully explains most of the currently available data

influence of paleotopography base level and sedimentation rate on estuarine system response to the holocene sea level rise the example of the marais vernier seine estuary france the response of coastal systems to allogenic forcing factors is of interest to diverse research communities including those interested in global change sequence stratigraphy and modelling quaternary systems are of particular interest because they provide analogues for ancient rock records to understand the processes responsible for the sedimentary evolution of estuarine systems it is necessary to study as many fluvial systems as possible the objective of this review of the sedimentary evolution of a coastal marsh is to describe the influence of glacial paleotopography on the record of climatic and sea level changes the marais vernier located at the interface between the marine and fluvial parts of the estuary is a part of the lower seine valley wetland network which formed after the last glacial maximum previous studies have described the holocene filling which is composed of peat and detrital material deposited following climatic and sea level changes to understand the sedimentary evolution a paleotopographical based on drillings and electromagnetic surveys and a chronological framework based on radiocarbon dates for the southern peat marsh were defined the peat marsh paleotopography has three erosional surfaces the s1 surface is the oldest and also the highest topographically the s2 surface is younger wider and incised below the s1 surface the s3 surface the youngest of the three is narrow and deeply incised radiometric ages were considered on the basis of their geographical position in relation to the s3 surface prior to 7 5 ka cal bp sediments accumulated only above the narrow area described by the s3 surface at a rate of 5 5 mm yr 1 after 7 5 ka cal bp shortly after the flooding of the seine estuary sediments accumulated as peat deposits over the entire peat marsh at a rate of 3 mm yr 1 in response to the sea level rise the paleotopography delimits the area of deposition during the holocene and thus plays a critical role in determining the vertical accretion rate expressed as a thickness prior to 7 5 ka cal bp the vertical accretion rate 5 5 mm yr 1 was less than that observed for the seine estuary 6 8 mm yr 1 however rate of sea level rise and sediment supply which also affects sediment accumulation rates vary in northwestern europe during the holocene therefore although the marais vernier is a good illustration of paleotopographic influence the effects of autocompaction sea level and sediment supply complicate efforts to quantify the degree to which it controls sediment accumulation

holocene paleoclimate inferred from salinity histories of adjacent lakes in southwestern sicily italy marked uncertainties persist regarding the climatic evolution of the mediterranean region during the holocene for instance whether moisture availability gradually decreased remained relatively constant or increased during the last 7000 years remains a matter of debate to assess holocene limnology hydrology and moisture dynamics the coastal lakes lago preola and gorgo basso located in southwestern sicily were investigated through several stratigraphic analyses of ostracodes including multivariate analyses of assemblages transfer functions of salinity and biochemical analyses of valves sr ca 18o and 13c during the early holocene the gorgo basso and lago preola ostracode records are similar after an initial period of moderate salinity 1690 6100 mg l from ca 10 000 8190 cal yr bp syndepositional or diagenetic dissolution of ostracode valves suggests that salinity declined to 250 mg l from ca 8190 to 7000 cal yr bp at both sites after ca 6250 cal yr bp the ostracode records are strikingly different lago preola became much more saline with paleosalinity values that ranged from 2270 to about 24 420 mg l we suggest that lago preola s change from a freshwater to mesosaline lake at about 6250 cal yr bp was related to sea level rise and resulting intrusion of seawater influenced groundwater in contrast gorgo basso remained a freshwater lake the salinity of gorgo basso declined somewhat after 6250 cal yr bp in comparison to the early holocene ranging from about 550 to 1680 mg l cypria ophtalmica a species capable of rapid swimming and flourishing in waters with low dissolved oxygen levels became dominant at approximately the time when greek civilization took root in sicily 2600 cal yr bp and it completely dominates the record during roman occupation roughly 2100 to 1700 cal yr bp these freshwater conditions at gorgo basso suggest high effective moisture when evergreen olive oak forests collapsed in response to increased greco roman land use and fire ostracode valve geochemistry sr ca 18o suggests significant changes in early vs late holocene hydrochemistry either as changes in salinity or in the seasonality of precipitation harmonizing the autecological and geochemical data from gorgo basso suggests the latter was more likely with relatively more late holocene precipitation falling during the spring summer and fall than winter compared to the early holocene our ostracode inferred paleosalinity data indicate that moisture availability did not decline during the late holocene in the central mediterranean region instead moisture availability was lowest during the early holocene and most abundant during the late holocene

a hoxnian interglacial doline infilling at slade oak lane denham buckinghamshire england site investigations for the m25 motorway at denham proved a maximum depth of 37 5 m of deposits filling an enclosed hollow up to 40 m across beneath a small seasonally dry valley near higher denham this previously unknown very steepsided hollow is infilled with gravel and sand partially laminated clayey silt and pebbly clay within these deposits a bed of organic clay mud up to 4 5 m in thickness is present resistivity survey of the hollow proves that it is completely enclosed palaeobotanical investigation shows that the organic sediment contains fossil pollen spores and macroscopic remains the pollen spectra indicate that the sediments accumulated during the later half of the hoxnian interglacial stage ho iii iv macroscopic remains include relict species dulichium arundinaceum and brasenia schreberi the latter being new to the hoxnian stage the evidence for waterlevel fluctuation during the interglacial at the site is discussed the origin of the hollow is considered and the conclusion reached is that it is a doline formed by solution of the underlying chalk bedrock the infilling of the basin is attributed to collapse solifluction and slope wash of local material under cold climates before and after the interglacial the interglacial sediment is a shallow water pool accumulation the hollow is thought to have been formed originally as a solution pipe beneath the thames gerrards cross gravel rapid drainage of a neighbouring glacial lake causing the major collapse in the late anglian stage subsequent infill took place during the later part of the anglian hoxnian and wolstonian stages and possibly even later heavy mineral analyses of the silt rich sediment above and beneath the interglacial deposits are appended and indicate that it is almost all of local reading beds material

composition and origin of some brickearths on the chiltern hills england summary brickearths some associated with lower palaeolithic industries occur at several sites on the chalk interfluves of the chiltern hills they usually occupy funnel or basin shaped depressions in the underlying chalk surface and are surrounded and often overlain by reddish flinty clays petrographic studies of these silty deposits show they are composed partly of wolstonian and or anglian loess and partly of silt clay and sand from palaeocene reading beds or plateau drift largely reading beds weathered and disturbed in the late tertiary and quaternary the depressions probably originated as dolines which were infilled by mixed sediments washed or soliflucted from adjacent land surfaces during several stages of the later quaternary micromorphological evidence suggests that some of the brickearths were affected by development of ground ice clay illuviation and rubefication before the last major cold stage devensian

stratigraphy and origin of new forest brickearths england the thin loamy brickearth deposits overlying the flinty terrace gravels of the new forest are divided into older and younger members the lower older brickearth includes sediments thought to be mainly loess with some aeolian sand and possible river floodloam overbank sediment these share the common feature of palaeo argillic soil horizons in their upper layers two separate phases of pre holocene temperate pedogenesis often can be distinguished in the palaeo argillic horizons the lower brickearth is the most extensive pre devensian loess in britain the upper younger brickearth consists mainly of late devensian oxygen isotope stage 2 loess but its lower layers also contain fine sand derived mainly from local tertiary strata both brickearths occur on all the terrace surfaces of the new forest and indicate that the terraces date from oxygen isotope stage 6 or earlier

the quaternary of the british isles factors forcing environmental change this paper considers the processes that have controlled cool temperate latitude terrestrial environments over the last ca 3 ma with particular reference to the british isles a scheme is proposed that is based on the processes that act on the land over any given period of time and are the product of climate modulated by rock type the resisting agent and relief determined by tectonics and antecedent relief forming factors climate is generalised in terms of the range and rates of climate change determined by orbital forcing during precession cycles climate change was small and insolation levels were forced by chemically and biologically driven processes the period of obliquity cycles is characterised by patterns of climate change in which physical processes became effective and high magnitude fluvial and slope processes were reinforced by periglaciation and glaciation in susceptible regions eccentricity cycles include climate extremes of longer duration and glaciation and periglaciation were the major contributors to landscape change sediment transfer and sediment mixing these climate forced processes produce distinctive landform sediment and soil assemblages characteristic of particular episodes of quaternary time the lags between the successive systems are identified copyright 2010 john wiley sons ltd

the groundwater budget a tool for preliminary estimation of the hydraulic connection between neighboring aquifers abstract groundwater management authorities usually use groundwater budget calculations to evaluate the sustainability of withdrawals for different purposes the groundwater budget calculation does not always provide reliable information and it must often be supported by further aquifer monitoring in the case of hydraulic connections between neighboring aquifers the riardo plain aquifer is a strategic drinking resource for more than 100 000 people water storage for 60 km2 of irrigated land and the source of a mineral water bottling plant over a long period the comparison between the direct recharge and the estimated natural outflow and withdrawals highlights a severe water deficit of approximately 40 of the total groundwater outflow a groundwater budget deficit should be a clue to the aquifer depletion but the results of long term water level monitoring allowed the observation of the good condition of this aquifer in fact in the riardo plain the calculated deficit is not comparable to the aquifer monitoring data acquired in the same period 1992 2014 the small oscillations of the groundwater level and the almost stable streambed spring discharge allows the presumption of an additional aquifer recharge source the confined carbonate aquifer locally mixes with the above volcanic aquifer providing an externally stable recharge that reduces the effects of the local rainfall variability the combined approach of the groundwater budget results and long term aquifer monitoring spring discharge and or hydraulic head oscillation provides information about significant external groundwater exchanges even if unidentified by field measurements and supports the stakeholders in groundwater resource management

the loess section at borden kent se england a 5 3m profile originally described as loess with a buried interglacial soil is reinterpreted from petrographic evidence and thermoluminescence dating as a holocene colluvial accretionary soil mineralogical analyses of coarse silt 16 63 m fractions suggest that most of the silty colluvium was derived from weathered thanet beds upslope though some loess was incorporated during the final depositional phase thin sections show that clay illuviation occurred penecontem poraneously with deposition of colluvium thermoluminescence properties suggest partial optical bleaching of the grains during rapid deposition which is consistent with a holocene colluvial origin

lithofacies stable isotopic composition and stratigraphic evolution of microbial and associated carbonates green river formation eocene piceance basin colorado lacustrine carbonates of the eocene green river formation crop out on the western margin of the piceance basin and the eastern margin of the uinta basin in western colorado this area allows tracing of vertical and horizontal facies variation over hundreds of meters limestone beds consist of littoral to sublittoral lithofacies bioclastic and oolitic grainstones oolitic wackestone intraclastic rudstone stromatolites and thrombolites facies form upward deepening cycles that start with sharp based grainstones and packstones followed by stromatolites or thrombolites and capped by fine grained stromatolites and or oil shale deposits the vertical succession of carbonate deposits correlates with evolutionary lake stages the succession starts with grainstone deposits rich in ostracods and gastropods that correspond to an initial freshwater lake thrombolites capped by laminated stromatolites or coarse agglutinated stromatolites correlate with a higher salinity transitional lake deepening upward cycles as much as 5 m 16 ft thick of thrombolites agglutinated stromatolites and fine grained stromatolites occur in the highly fluctuating lake the upper section is dominated by laminated stromatolites that correspond to a rising lake stable isotope 18o and 13c values covary and range from 8 to 0 8 and 3 to 5 respectively the 18o values indicate carbonate precipitating water evolved from fresh to saline and became less saline in the upper green river negative excursions of 13c values correspond to lake level rises and positive excursions of 13c values occur during lake level falls syndepositional to burial diagenesis modified carbonate porosity early dissolution is followed by burial compaction and fracturing compaction and late calcite cements occluded primary and secondary porosity

sedimentary processes in the great lakes sediments in the great lakes are subject to four general categories of processes input transport deposition and postdepositional alteration sedimentary input is from coastal erosion 64 riverine input 26 atmospheric transport 3 and several lesser sources 7 once in the lake sediments are transported to their place of deposition along the bottom and or in suspension depending upon grain size and density the rate of deposition in the great lakes is variable and ranges from zero in some areas to over 6000 g m sup 2 yr sup 1 in the eastern basin of lake erie after deposition sediments undergo bioturbation dissolution of carbonate and opal remobilization of many metals followed by reprecipitation within the surficial oxidized layer and degradation of organic compounds

comparison of modern and ancient vertisols developed on limestone in terms of their geochemistry and parent material identification of paleosol parent material can be difficult a common simplistic assumption is that nonpedogenic strata directly beneath paleosols are representative of the parent material field relationships petrography and geochemical massbalance were used to test the simple hypothesis that the parent material of both an early carboniferous late mississippian vertic vertisol like paleosol and a modern analog soil vertisol was immediately subjacent marine carbonate rock an alternative hypothesis also tested was that the paleosol formed primarily from siliciclastic sediment deposited on top of the carbonate the modern ancient analog comparison is valid because both the paleosol and the modern soil have high clay contents extensive shrink swell features and rest directly on top of marine carbonate substrates field and thin section observations indicate minor assimilation of marine carbonate into both the paleosol and soil matrices mass balance of both the paleosol and soil calculated assuming that the subjacent carbonate was the parent material and that ti was immobile during weathering indicated 25 75 net volume loss during weathering and 25 99 net losses of many alkali alkaline earth and redox sensitive elements however calculations based on an alternative hypothesis of clayshale parent material for the paleosol indicated only 10 25 volume loss and lower translocation losses for weathering of this material the insoluble residue content of the dolostone would require that a fourfold volume reduction during weathering occurred if the dolostone were the only parent material if the paleosol formed from clayshale then significantly less volume loss characterised weathering these results collectively illustrate that the simplest interpretation of paleosol parent material may not always be correct and that paleosols can be derived from weathering of more than one parent material d 2002 elsevier science b v all rights reserved

holocene evolution of a wetland in the lower seine valley marais vernier france estuaries like that of the seine river in nw europe developed in incised fluvial valleys after the last glacial maximum since the 1940s several authors have studied the largest wetland of the seine estuary the marais vernier to understand depositional environments during holocene infilling we reinterpret previous research based on new and published data for example fill thickness and material source to 1 describe facies and depositional environments 2 reconstruct palaeoenvironmental evolution 3 show the influence of local and global forcing on depositional environments before 7000 6000 cal bc terrestrial material was deposited because of catchment erosion related to changes in climate just before 7000 6000 cal bc estuarine material began to be deposited in low lying areas in response to sea level rise while terrestrial material still settled at higher elevations after this but before 5850 5710 cal bc estuarine material areas began to accumulate at both high and low elevations this marked a general flooding of the marais vernier synchronous with that at the seine estuary mouth soon after peat accumulated over a wide area as a response to a local change in accommodation and a worldwide drop in sea level a tidal channel developed to the west of the marais vernier providing minerogenic material after 1130 900 cal bc human influence becomes increasingly clear in the record this record of regional change during the holocene can serve as a reference for further studies in the area

meso cenozoic morphotectonic evolution of southern norway neogene domal uplift inferred from apatite fission track thermochronology apatite fission track aft thermochronology of precambrian and paleozoic basement samples from southern norway reveals a post paleozoic exhumation history related to offshore mesozoic and cenozoic extensional basin development the data indicate two major phases of rapid exhumation a first mesozoic phase started in the triassic 220 ma in the east and south of the study area and migrated to the west where jurassic 160 ma ages of exhumation predominate a second event is indicated by thermal history modeling of aft ages and track length distributions it is inferred to be neogene in age initiated at about 30 ma and it produced a domal pattern of aft isochrons which follow present day topographic elevation youngest aft ages 100 ma are encountered at sealevel in the inner fjords near the areas of highest topography ages increase radially outward to the mountain peaks and the coastlines forward modeling of age elevation patterns suggests that mesozoic geothermal gradients were 10 15 c km higher than the present value of 20 c km during the triassic and jurassic a total of 1 3 3 5 km of overburden was removed from the study area assuming a 30 c km geothermal gradient for that period we attribute this to rift margin erosion as a result of erosional base level lowering and flank uplift as evidenced by thick continental clastic sequences deposited in triassic jurassic half grabens in the north sea basins we propose that 1 5 2 5 km of neogene exhumation were a result of late stage domal uplift this is supported by basinward dipping pre neogene strata in the basins surrounding southern norway and the infill of a 1 to 2 km thick neogene sediment wedge containing various internal unconformities domal uplift probably started in the late oligocene may have been amplified in the pliocene and was overprinted by plio pleistocene glacial erosion maximum neogene tectonic uplift is estimated at approximately 1 1 5 km radially decreasing outward to a value 500 m near the shoreline neogene domal uplift is coincident with oligocene and pliocene plate reorganizations in the north atlantic similar neogene domes are found around the norwegian greenland sea i e svalbard and the barents sea northern norway east greenland suggesting a regional tectonic cause the onset of neogene uplift postdates major volcanism and continental breakup by 25 m y and predates plio pleistocene glaciations its origin is possibly a combination of induced mantle convection resulting in thermal erosion of the lithosphere and the operation of intraplate stresses

synorogenic evolution of large scale drainage patterns isotope paleohydrology of sequential laramide basins in the past decade we and others have compiled an extensive dataset of o c and sr isotope stratigraphies from sedimentary basins throughout the paleogene north american cordillera in this study we present new results from the piceance creek basin of northwest colorado which record the evolving hydrology of the eocene green river lake system we then place the new data in the context of the broader cordilleran dataset and summarize implications for understanding the synorogenic evolution of large scale drainage patterns the combined data reflect 1 a period of throughgoing foreland rivers heading in the sevier fold and thrust belt and flowing east 2 ponding of freshwater lakes in the foredeep as laramide uplifts blocked drainage 3 hydrologic closure that led to both intensive evaporation in the terminal sink of the piceance creek basin and integration of catchments over length scales 1000 km 4 infilling of basin accommodation by southward migrating magmatism in distal catchments leading to the freshening and demise of intraforeland lakes that also stepped south over time

development of a clay rich interval above a limestone substrate in the condroz region of southern belgium a profile comprising a limestone substrate overlain by a clay rich interval which represents a common sequence was studied with the objective of determining the relationship between substrate and cover the profile was characterized by various types of mineralogical and chemical analyses and by a micromorphological study the mineralogical and chemical data demonstrate that the cover is unrelated to the parent rock including all horizons below the loess derived ap horizon thin section observations show that the basal c3 horizon is largely composed of illuvial clay deposited around claystone fragments resulting in a fabric that together with profile position relates the interval to so called beta horizons in higher parts up to a level recognized as a lithological discontinuity based on mineralogical composition the profile largely consists of fragments of clay coatings and disintegrated claystone fragments with an overall upward increase in degree of pedoturbation the source of the clay is assumed to be cenozoic deposits that are known to occur in the region the main conclusion of this study is that clay intervals overlying limestone can have a complex mode of development to be studied by a combination of methods and with implications for the valorization of existing soil maps

the neogene and quaternary clay with flints north and south of the english channel comparisons of distribution age genetic processes and geodynamics weathered residual accumulations termed clay with flints argiles a silex overlying cretaceous deposits are widespread in southern england and northwestern france geological and pedological studies and some field surveys indicate their distribution nature age and origin in france the microfaunas preserved in the hollow flints of the clay with flints demonstrate the preservation of the parent chalk stratigraphy in the sections studied i e the clay with flints corresponds to in situ weathering profiles however in england and in france an important part of the clay component is derived from a thin veneer of basal tertiary sediment overlying sub tertiary marine erosion surfaces of various palaeogene transgressions in england as in france the youngest generation of clay with flints can be dated from late pliocene to quaternary it formed after removal of different cenozoic deposits on many plateaus and during the downcutting of pleistocene rivers the most visible effect of subsequent weathering profile development is irregular dissolution of the underlying chalk to produce deep karstic pipes into which the clay with flints has slumped other pedological processes include rubification clay illuviation and cryoturbation clay with flints also provides evidence of quaternary palaeoenvironments cenozoic continental palaeosurfaces and their vertical deformation copyright 2003 john wiley sons ltd

the mineral springs of the scrajo spa sorrento peninsula italy a case of natural seawater intrusion this paper deals with the mineral springs feeding the scrajo spa in the sorrento peninsula southeast of naples approximately 6 km from castellammare di stabia another spa location the scrajo mineral water is sulphureous salt bromine iodic and co2 rich the two hydromineral areas fall within the groundwater basin of mt faito formed chiefly by limestones due to the high permeability of the limestones there is considerable rainwater infiltration which recharges a basal fresh groundwater resting on denser seawater this groundwater body feeds the mineral springs of the scrajo spa the springs of castellammare di stabia and some submarine springs all the data gathered for the scrajo springs led to propose the following mineralisation scheme 1 the basal fresh groundwater of mt faito on underlying seawater receives endogenous contributions of co2 and h2s which cause a natural seawater intrusion within the fresh groundwater 2 the upwelling of gases would appear to occur via the major faults which bound sorrento peninsula to the nw 3 during the year the chemistry of the springs changes according to different degrees of seawater intrusion the minimum occurs in june and the maximum in november the close interaction between the sea and the scrajo s mineral waters but also those of castellammare di stabia highlights their particular vulnerability not only to over extraction of groundwater but also to climate change finally a hypothesis is presented to explain the connection between the mineral waters rich in co2 and h2s and the concentration of karst phenomena observed in the scrajo area

recent work on quaternary paleosols in britain abstract apart from observations of isolated exposures of buried paleosols most of the early paleopedological work in britain was concerned with surface non buried paleosols principally the paleo argillic soils of the current system of soil classification for england and wales within the last 20 years more extensive buried interglacial soils have been discovered in parts of east anglia and the lake district those on a sequence of buried pre anglian terraces of the proto thames in east anglia strongly resemble the surface paleo argillic soils comparison of the two would show whether the paleo argillic soils should be subdivided in any way and could clarify diagenetic processes affecting buried soils and the extent to which early soil features are lost by continuing pedogenesis buried arctic structure soils were formed in many different periods including the dimlington and loch lomond stadials of the late devensian since 26 000 bp if these can be correlated with the frost features that occur widely in paleo argillic and other surface soils they will also clarify the pedogenetic histories and improve the classification of british surface soils buried late devensian interstadial soils are also widespread and provide evidence for the ecological effects of the rapid climatic changes occurring between 13 000 and 10 000 bp those exposed in recent excavations related to the channel tunnel provide the first evidence for clay illuviation at this time in britain

flow in the lower continental crust as a mechanism for the quaternary uplift of south east england constraints from the thames terrace record abstract the sequence of terraces of the river thames in south east england has been shown to date from the early pleistocene onwards and to provide an indication of the quaternary uplift history of the region using this evidence supplemented by altitudes of pliocene and early pleistocene marine sediments we have determined the pliocene and quaternary uplift histories of five representative localities clacton colchester and dartford for the lower thames and cookham and reading for the middle thames these uplift histories have been modelled using a physics based technique which calculates the isostatic response involving flow in the lower continental crust induced by cyclic loading at the earth s surface our results suggest that the late pliocene and early pleistocene part of the uplift history of our study region was initiated following the deterioration in climate starting at 3 1 ma which marked the start of upland glaciation elsewhere in europe the later increase in uplift rates in the middle pleistocene followed the start of intensified cyclic loading by very large continental ice sheets during and after oxygen isotope stage ois 22 at 0 87 ma dartford cookham and reading in the interior of south east england are all shown to have begun to uplift quite rapidly at rates of up to 0 1 mm a 1 following the start of forcing at 3 1 ma they have since uplifted by distances which increase gradually westward from 200 to 250 m of which a uniform 70 m has occurred since ois 22 at 0 87 ma in contrast clacton and colchester near the present north sea coastline experienced slow subsidence until the late early pleistocene but have nonetheless uplifted since ois 22 by similar distances to the other sites

slope clay with flints biefs a silex as indicators of quaternary periglacial dynamics in the western part of the paris basin france the lithology and distribution of the clay with flints occurring on slopes called biefs a silex in french suggests a twofold classification of these deposits according to slope angle biefs a silex formed as a solifluction deposit under quaternary periglacial conditions during valley development two biefs a silex facies suggest two phases of development between 800 000 and 20 000 yr bp copyright 2003 john wiley sons ltd

lacustrine varve formation through time abstract studies using sediment traps in lakes reveal that the seasonal flux of sediment regulates both the composition and timing of deposition of materials that reach the bottoms of lakes if the bottom waters of a lake are partly or totally anoxic the seasonally deposited materials are preserved as annual groupings of laminae varves common components that form individual laminae consist of allochthonous clastic material derived from the drainage basin precipitated carbonate minerals diatom frustules iron rich and manganese rich flocs autochthonous organic detritus and autochthonous and allochthonous materials resuspended from the bottom the style of varving has changed over geologic time reflecting changes in biologic evolution and types of materials available precipitated iron rich laminations were common in the middle precambrian graded sets of clastic organic laminations persisted through the precambrian prior to the evolution of bioturbating benthic organisms glaciolacustrine varves appear to have retained their distinctive character through time carbonate rich varves occurred sporadically in the precambrian and phanerozoic with the exception of diatoms major components of modern lacustrine varves were present through the paleozoic and mesozoic and yet varves are rare in strata of these ages and may have accumulated in marine to brackish water environments diatoms were introduced into lacustrine systems in early tertiary time and are common components of varves from then on diatom laminae combined with a greater chance for geologic preservation of younger lake deposits have increased the number of geologically young occurrences of varved sediments however seasonal associations of modern varve components and the processes they represent are present in ancient deposits and provide clues to the interpretation of ancient environments

upper cretaceous feldspars in the cenozoic limagne basin a key argument in reconstructing the palaeocover of the massif central france abstract the northern part of the n s trending basin of the limagne graben located in the northern part of the massif central france contains oligocene and miocene calcareous lacustrine deposits the area is known for its stromatolite reefs surrounded by marl clay and uncemented carbonate sand with oncolites because the origin of the carbonate accumulated by cyanobacteria has long been debated the clayey deposits associated with the stromatolites were analysed using xrd sem and k ar dating methods the results show a monotonous assemblage of carbonates dioctahedral smectite illite smectite reichweite r 0 glauconitic illite and abundant orthoclase detrital minerals such as quartz and detrital illite are found near the basin s borders but are very scarce in its central part indicating a lack of detrital input from the regional basement hence the abundant orthoclase found in all the clayey deposits of the limagne basin cannot be linked to erosion of the surrounding hercynian basement the sem analysis showed the orthoclase crystals to have a tabular morphology with sharp boundaries and to be embedded within a clay matrix whilst the k ar dating of the orthoclase and glauconitic illite yielded ages ranging from 90 to 66 2 ma i e turonian to maastrichtian these two results clearly indicate that the fill of the limagne basin composed mainly of carbonate clay and orthoclase must have been partly due to the erosion of an upper cretaceous sedimentary blanket once covering the massif central basement this cover was probably constituted of chalk dioctahedral smectite i s and glauconitic illite associated with authigenic orthoclase and flint flints are found reworked in the alluvial formations of the late pliocene lower bourbonnais sands and clays sables et argiles du bourbonnais and in the pleistocene terraces moreover relicts of the upper cretaceous cover were preserved during the sedimentary filling of the cenozoic limagne basin authigenic orthoclase of similar shape has been described in the chalk group of the paris basin and from localities in northern france and belgium the mineral is rare in the turonian chalk but increases rapidly at the base of the coniacian to campanian chalk it has also been noted that the number of orthoclase crystals increases as the quantity of clastic components decreases similar orthoclase crystals were found associated with dioctahedral smectite in the decarbonated residues of the coniacian to santonian chalk from fecamp and etretat northern france moreover our results are consistent with other data from within and around the paris basin such as the palaeogeography and facies distribution of the chalk formations the residual flints in the clay with flints of the southern paris basin and around the morvan and apatite fission track thermochronology data from the hercynian basement of the massif central and the morvan all these data indicate a major connection between the paris basin and the tethys and an extensive palaeocover on the massif central and morvan basement

uplift driven valley incision and river terrace formation in southern england outside the limits of middle pleistocene glaciation the river basins of southern england contain long cenozoic terrestrial sedimentary records of greatest importance are the river terrace sequences which contain biostratigraphical and sedimentary evidence that testifies to the high amplitude climatic changes of the quaternary however trends in valley development cannot easily be accommodated within the framework of quaternary climatic change it is argued in this paper that episodic incision and terrace development result from uplift a consequence of the interplay between continuing alpine orogenic movements and erosion driven isostasy using a simple linear model height age an uplift rate of ca 7 cm ka 1 is estimated for the terrace sequence in the upper thames valley this preliminary model is evaluated using the records of adjacent basins 1997 john wiley sons ltd

a re examination of the evidence for a plio pleistocene marine transgression on the chiltern hills i structures and surfaces borehole and surface outcrop data are used to construct sub chalk sub upper chalk and sub tertiary contour maps for the chiltern area the results show a southwest northeast monocline which coincides with the change of slope at the lower boundary of the morphological bench on the chalk dipslope that wooldridge and linton attributed to plio pleistocene marine erosion younger northwest southeast synclines coincide with the main transverse river valleys of the chilterns the monoclinal flexuring casts doubt on the value of the bench as evidence for a plio pleistocene transgression

spatio temporal patterns of holocene environmental change in southern sicily abstract few examples of natural forest remain near the mediterranean coast therefore it is difficult to study how coastal forests respond to climatic change or their resilience to human impact we developed new sedimentary record of holocene vegetation and fire history at lago preola a coastal lake in southwestern sicily italy in order to verify the existence of forest at large scale on the coast we compare pollen from lago preola a medium sized lake 33 ha to gorgo basso a small lake 3 ha located nearby with the aim of separating local from extra local vegetation dynamics through time using pollen percentages and influx we then compare lago preola pollen to the record from biviere di gela a large lagoon 120 ha situated 160 km to the east in southern sicily to examine differences in vegetation dynamics between the two coastal areas during the holocene lake level reconstructions and ostracode analyses from lago preola provide vegetation independent evidence of climate change and help to disentangle human and climatic impacts on vegetation pollen data indicate pistacia dominated shrublands replaced open grasslands in the region surrounding lago preola by 9500 cal yr bp this change coincided with rising lake levels and the development of an ostracode fauna typical of fresh waters evergreen forest dominated by quercus ilex and olea europaea started to expand by 7000 cal bp and consolidated at 6500 cal yr bp when lake levels were near their holocene high similarities between pollen from lago preola and gorgo basso demonstrate that forest was the dominant vegetation type in coastal sicily during the middle holocene at both regional and local scales and even developed in the drier climatic setting around biviere di gela lake levels fell at lago preola after 7000 cal yr bp with a strong decline accompanied by increasing salinity after 4500 cal yr bp however no transition in vegetation matched these inferred hydrological changes instead forests persisted in the surrounding region until 2200 cal bp when human disturbance intensified we propose that different climatic factors control lake levels and vegetation in coastal mediterranean ecosystems whereas lake levels are most sensitive to the abundance of winter precipitation coastal forests depend on spring precipitation and are limited by the length of summer drought moisture availability remained suitable for evergreen forests in coastal sicily during the late holocene and humans not a drier climate drove the regional forest decline

geoarchaeological studies associated with remedial measures at silbury hill wiltshire uk abstract silbury hill near marlborough wiltshire uk is one of the largest prehistoric mounds in europe characterised by uncertain structure and unusual burial conditions internal collapses occurred in autumn 2000 as a result of the incomplete refilling of tunnels dug in the last few centuries planning for the repairs has provided an opportunity to examine samples from recent exploratory boreholes and the 1960s excavations this paper brings together the results of these investigations comparing the materials from inside the hill with nearby soil profiles the truncated nature of the old ground surface and the extensive multiple iron pans found inside the hill are discussed along with their implications for construction and post depositional processes

eocene atmospheric co2 from the nahcolite proxy estimates of the atmospheric concentration of co 2 co 2 atm for the hothouse climate of the early eocene climatic optimum eeco vary for different proxies extensive beds of the mineral nahcolite nahco 3 in evaporite deposits of the green river formation piceance creek basin colorado usa previously established co 2 atm for the eeco to be 1125 ppm by volume ppm here we present experimental data that revise the sodium carbonate mineral equilibria as a function of co 2 and temperature co precipitation of nahcolite and halite nacl now establishes a well constrained lower co 2 atm limit of 680 ppm for the eeco paleotemperature estimates from leaf fossils and fluid inclusions in halite suggest an upper limit for co 2 atm in the eeco from the nahcolite proxy of 1260 ppm these data support a causal connection between elevated co 2 atm and early eocene global warmth but at significantly lower co 2 atm than previously thought which suggests that ancient climates on earth may have been more sensitive to a doubling of co 2 atm than is currently assumed

micromorphology of soils and palaeosoils in belgium an inventory and meta analysis abstract a study of the literature dealing with micromorphology of belgian soils and palaeosoils is presented most soils in belgium developed in quaternary covers sandy in the north becoming more silty towards the south and mixed with more or less important amounts of substrate material in addition azonal soils occur in the recent dunes the marine polders and the alluvial areas the main pedogenic micromorphological characteristics are bioturbation clay illuviation features in the more silty materials and spodic features in the more sandy materials glauconite plays an important role in pedogenesis throughout most profiles features related to a sub recent pedogenic environment are recognised pointing to polygenetic soil formation impact of periglacial conditions is often visible bog ores in alluvial plains have a complex mineralogical composition and microfabric buried palaeosoils and soil sediments are discussed separately according to their age whereas polygenetic soils are treated together with the recent soils according to their geographic position for some areas e g the polders the sandy area of flanders and the pays de gaume in the southernmost part of belgium only little micromorphological information is available most soils studied were situated under natural vegetation studies of cultivated soils are rather rare

timing and mechanisms of north atlantic cenozoic uplift evidence for mantle upwelling postrift domal uplift patterns are a distinct feauture of northern north atlantic margins on the basis of apatite fission track data offshore seismic stratigraphy geomorphology gravity and seismic tomography we argue that southern norway is characterized by predominantly neogene domal uplift currently available data suggest similar processes for other uplifted regions such as spitsbergen northern norway the british isles aad parts of east greenland

stratigraphic evidence for a deep eocene lake uinta piceance creek basin colorado relief on a prograding clastic complex is used to estimate the water depth of eocene lake uinta in the piceance creek basin of western colorado relief of as much as 412 in is present today on the complex postdepositional compaction can account for only about 100 m of this relief therefore the remaining 312 m appear to represent paleorelief on the floor of lake uinta the lake was apparently more than 300 m deep authigenic saline minerals were precipitated in the unlithified sediments of the deeper areas of the lake suggesting that at least the lower part of the water column was highly saline the evidence presented here indicates that the deep stratified lake model is more appropriate than the more generally accepted shallow or playa lake model for lake uinta

recognition of tectonic events in undeformed regions contrasting results from the midland platform and east midlands shelf central england apatite fission track and vitrinite reflectance data from central england demonstrate how these techniques can reveal otherwise unrecognized tectonic and or palaeothermal episodes in apparently tectonically stable areas the results document the transition from an inverted basinal region in the north east midlands shelf to a tectonically stable platform in the south midland platform afta data from the region reveal two discrete cooling episodes in the early and late tertiary maximum palaeotemperatures from afta and vr data in outcrop samples define a consistent increase from 50 c in lower cretaceous and upper jurassic units in the se to around 80 90 c in triassic and older units in the nw these early tertiary palaeotemperatures reflect a combination of deeper burial and elevated basal heat flow results from the rufford 1 well define an early tertiary palaeogeothermal gradient of 40 5 c km 1 32 50 c km 1 at 95 confidence limits corresponding to deeper burial by 1450 m of additional section 1 1 2 2 km at 95 confidence limits subsequently removed by tertiary erosion in contrast geological considerations suggest a maximum overburden of 800 900 m above the base of the lower jurassic in the vicinity of rugby where palaeotemperatures at outcrop are similar to those near the rufford 1 location the discrepancy between stratigraphic and palaeo thermal reconstruction of former burial depths often noted in earlier studies remains unresolved the late tertiary episode is much less well constrained but results from rufford 1 may require between 910 and 1650 m of eroded section thus much of the total amount of removed overburden may have been removed during the late tertiary results from the apley barn borehole oxfordshire reveal a late tertiary palaeothermal episode characterized by a highly non linear palaeotemperature profile which probably reflects local heating due to passage of hot fluids despite stratigraphic evidence for some early tertiary erosion results from this borehole show no evidence of early tertiary effects major early and late tertiary exhumation was limited to regions underlain by older palaeozoic basins while regions overlying palaeozoic basement were more stable experiencing significantly less exhumation we suggest this reflects the preferential reactivation of the weaker basinal regions as a result of compressional events at plate margins our results emphasize the importance of incorporating results from both inverted and non inverted areas in understanding the causal mechanisms of uplift and inversion and highlight the importance of testing apparent stability using palaeo thermal methods

long term trend and fluctuations of karst spring discharge in a mediterranean area central southern italy karst springs in central southern italy are largely exploited for the human consumption since the roman times and currently feed some tens of millions inhabitants with tap water of high quality unlike other karst springs they are characterized by a steady rate during the year with modest seasonal variability however the effects of climate changes are being strongly perceived in central and southern italy as in the rest of the mediterranean basin and groundwater is obviously also affected in this paper we analyze the discharge time series of some important karst springs in the region evaluating the trends and fluctuations in relation to rainfall regime on a yearly time scale the aim is to evaluate the response of these large karst aquifers in the mediterranean area to the recharge input variation the role of the north atlantic oscillation has also been considered trends and fluctuations have been highlighted by n years moving average and transforming the time series by the rescaled adjusted partial sum the results show that a drop in the discharge has occurred since 1987 with reductions ranging from 15 up to 30 although this negative trend is now possibly attenuating or even reversing as a final remark the spring discharge of the large karst aquifers in central southern italy can be assumed as a robust indicator for climate changes as it integrates the effects of precipitation and temperature variation in time and space