products of subglacial volcanic eruptions under different ice thicknesses two examples from antarctica late cenozoic subglacially erupted volcanic sequences are scattered throughout the antarctic peninsula two of the best preserved examples at mount pinafore alexander island c 5 5 6 ma and brown bluff graham land c 1 ma are complete enough to be regarded as sequence holotypes for this uncommonly preserved eruptive depositional setting despite a common glacial association the sedimentary lithofacies in the two outcrops suggest flowing and ponded water conditions respectively indicating significant differences in the depositional palaeoenvironments the original ice thicknesses exerted a major control on the lithofacies which resulted from each eruptive phase at mount pinafore the lithofacies were confined within a steep sided valley during successive eruptions beneath thin 100 150 m wet based ice the much thicker succession at brown bluff is a tindar tuya edifice which formed within a small basin probably 15 km across confined by ice 400 m thick

single crystal 40ar 39ar dating of the olorgesailie formation southern kenya rift single crystal laser fusion sup 40 ar sup 39 ar analyses and several conventional bulk fusion sup 40 k sup 40 ar dates have been used to determine the age of volcaniclastic strata within the olorgesailie formation and of associated volcanic and sedimentary units of the southern kenya rift in the principal exposures along the southern edge of the legemunge plain the formation spans the interval from approximately 500 to 1 000 ka deposition continued to the east along the ol keju nyiro river where a tuff near the top of the formation has been dated at 215 ka in these exposures the formation is unconformably overlain by sediments dated at 49 ka a possible source for the olorgesailie tephra the ol doinyo nyokie volcanic complex contains as ash flow dated at approximately 1 ma extending the known age range of this complex to encompass that of virtually the entire olorgesailie formation in the legemunge plain these geologic examples illustrate the importance of the single crystal sup 40 ar sup 39 ar dating technique whereby contaminant altered or otherwise aberrant grains can be identified and eliminated from the determination of eruptive ages for reworked or altered pyroclastic deposits the authors have presented a computer modeling procedure based on an inverse isochron analysis thatmore promotes a more objective approach to trimming sup 40 ar sup 39 ar isotope data sets of this type less

african monsoon variability during the previous interglacial maximum abstract little is known about centennial to millennial scale climate variability during interglacial times other than the holocene we here present high resolution evidence from anoxic unbioturbated sediments in the eastern mediterranean sea that demonstrates a sustained 800 yr climate disturbance in the monsoonal latitudes during the eemian interglacial maximum 125 ka bp results imply that before and after this event the intertropical convergence zone itcz penetrated sufficiently beyond the central saharan watershed 21 n during the summer monsoon to fuel flooding into the mediterranean along the wider north african margin through fossil river wadi systems that to date have been considered only within a holocene context relaxation in the itcz penetration during the intra eemian event curtailed this flux but flow from the nile with its vast catchment area was not affected previous work suggests a concomitant eurasian cooling event with intensified impact of the higher latitude climate on the mediterranean basin the combined signals are very similar to those described for the holocene cooling event around 8 ka bp the apparent type of concurrent changes in the monsoon and higher latitude climate may reflect a fundamental mechanism for variability in the transfer of energy latent heat between the tropics and higher latitudes

persistent solar influence on north atlantic climate during the holocene surface winds and surface ocean hydrography in the subpolar north atlantic appear to have been influenced by variations in solar output through the entire holocene the evidence comes from a close correlation between inferred changes in production rates of the cosmogenic nuclides carbon 14 and beryllium 10 and centennial to millennial time scale changes in proxies of drift ice measured in deep sea sediment cores a solar forcing mechanism therefore may underlie at least the holocene segment of the north atlantic9s 1500 year cycle the surface hydrographic changes may have affected production of north atlantic deep water potentially providing an additional mechanism for amplifying the solar signals and transmitting them globally

multi stage reef development on barbados during the last interglaciation by mapping the vertical and lateral distribution of reefal facies on the west and south coast of barbados we have produced a revised model of reef development for the last interglaciation we find that reef architecture around barbados has significant complexity including evidence for wave exposure related variations in reef geometry and at least 3 stages of reef development that were controlled by variations in sea level during the main stage of development an acropora palmata dominated reef crest aggraded 22 m in response to a minimum sea level rise of 20 m during stage 2 a sea cave was cut 3 4 m above the fossil reef crest possibly indicating that reef growth was terminated before sea level reached the highstand similar sequences elsewhere in the caribbean indicate that this early reef demise may not be a local phenomenon several reefs apparently stopped growing between 2 and 4 m and only in sheltered areas did they reach the highstand at 6 m as recorded by intertidal notches this pattern of reef demise has previously been related to rapid sea level rise at the end of the interglacial but stratigraphic data are equivocal the final stage of reef development on barbados occurred when sea level began to fall this fall was rapid leaving a thin but widespread veneer of reef crest deposits over the proximal reef front and discontinuous intertidal and shallow subtidal deposits capping the distal reef front although further dating is required to differentiate these three stages our only reliable u th tims date indicates that almost 50 of the exposed reef had accreted by 129 ka giving an estimate of 15 ka for the main aggradational stage furthermore reports of relict reef crests buried beneath these exposed deposits indicate that our revised model is incomplete and that earlier stages of reef growth occurred during the last interglaciation these earlier stages imply that sea level was at an interglacial level for as long as 20 ka supporting the devils hole record of interglacial duration unfortunately these estimates could not be verified directly because most of our u th data show major stratigraphic age reversals attributed to diagenesis this pattern is also evident in all other well dated reefal units in the caribbean and leads us to conclude that only diagenetically screened precise stratigraphically consistent coral dates can be used to directly estimate the duration of the last interglaciation

glaciovolcanic evidence for a polythermal neogene east antarctic ice sheet a paradigm has existed for more than 30 years that the basal thermal regime of the east antarctic ice sheet in victoria land made a fundamental transition from wet based to cold based either at ca 14 ma or after ca 2 5 ma the basal thermal regime is important because it determines the potential for unstable behavior in an ice sheet we have studied the environmental characteristics of subglacially erupted volcanic centers scattered along 800 km of the ross sea fl ank of the transantarctic mountains the volcanoes preserve evidence for the coeval paleo ice thicknesses and contain features diagnostic of both wet based and cold based ice conditions by dating the sequences we are able to demonstrate that the basal thermal regime varied spatially and with time between ca 12 ma and present it was polythermal overall and probably comprised a coarse temperature patchwork of frozen bed and thawed bed ice similar to the east antarctic ice sheet today thus an important shift is required in the prevailing paradigm describing its temporal evolution

planktic foraminifers and hydrography of the eastern and northern caribbean sea the distribution of living planktic foraminifers and their relation to the hydrography of the caribbean sea was investigated in plankton net tows and surface sediment samples taken along the antilles island arc during april may 1996 the planktic foraminiferal community was strongly influenced by spatial variations in salinity that were largely due to the influx of orinoco river water into the southeastern caribbean sea and inflowing sargasso sea water in the north along the antilles island arc globigerinoides ruber was the dominant species in the surface waters throughout in the southeastern caribbean sea where orinoco river outflow influences the planktic community standing stocks of planktic foraminifers 100 m between 4 and 50 specimens m 3 were medium to low the southeastern faunas between tobago and guadeloupe were characterized by increased proportions of neogloboquadrina dutertrei highest standing stocks of 159 specimens m 3 in the upper 20 m of the water column were recorded in the northeastern caribbean sea and the assemblages were characterized by high proportions of globigerinita glutinata associated with cyclonic eddies in the anegada passage where sargasso sea water flows into the caribbean sea low standing stocks of 18 specimens m 3 indicate oligotrophic conditions together with the oligotrophic surface waters the subtropical underwater enters the caribbean sea through the anegada passage in water depths between 100 and 300 m these waters are characterized by higher concentrations of globorotalia truncatulinoides relative to the adjacent water masses comparison of the living planktic foraminiferal fauna with empty test assemblages from the water column and from surface sediments shows that differences in the faunal composition mostly correspond to the distribution of water masses and to the differential dissolution of species in the vicinity of islands globigerinoides ruber reaches higher relative frequencies than in the open ocean pointing towards a higher tolerance of this species towards neritic conditions than in other species

lithofacies analysis and 40ar 39ar geochronology of ice volcano interactions at mt murphy and the crary mountains marie byrd land antarctica

late miocene valley confined subglacial volcanism in northern alexander island antarctic peninsula isolated late miocene volcanogenic sequences in northern alexander island antarctic peninsula form an unusual cogenetic association of volcaniclastic sandy gravelly lithofacies including tillites and volcanic lava hyalocalstite lithofacies using simple lithofacies analysis and theoretical considerations of hydrodynamic effects of subglacial eruptions valley confined volcanic activity beneth thin wet based ice is suggested the alexander island successions are complete enough to be regarded as model sequences for this uncommonly recorded type of eruptive depositional activity the sedimentary lithofacies represent resedimented tuffs and meltout or flow tills which were probably deposited in subglacial ice tunnels eroded or enlarged by volcanically heated meltwater the volcanic lithofacies formed by the interaction of hot magma with the ice tunnel walls generating abundant meltwater and water saturatedsediments resulting in the formation of heterogeneous masses of lava and hyaloclastite there is no obvious sequence organisation in the sedimentary sections this is probably due to a complex interplay of eruption related and environmental hydrodynamic factors affecting the relative proportions of water and entrained sediment

climate variations in europe over the past 140 kyr deduced from rock magnetism rapid shifts in climate during the last glacial are now well documented particularly from the oxygen isotope records of the two greenland ice cores grip1 2 and gisp23 in the grip record1 2 these climate events are also seen during the preceding eemian interglacial which may be an analogue for the future climate warmed by the greenhouse effect but these shifts are not found in the eemian section of the gisp2 core3 casting doubt on whether the rapid shifts in the grip oxygen isotope record really do represent a climate signal here we present magnetic susceptibility pollen and organic carbon records from maar lake deposits in the massif central france these data provide an independent record of past climate and we find that they correlate well with the ice core records during the last glacial during the eemian two rapid cooling events seen in our record also correlate with those seen in the grip ice core supporting the idea that rapid climate change did occur in the eemian interglacial and demonstrating that it extended to continental europe

epigenetic manganese occurrences within cretaceous strata of israel epigenetic manganese mineralization occurs within cretaceous carbonate strata of israel this mineralization is structurally controlled in southern israel manganese and iron bearing waters rising along fault zones precipitated these metals as different redox conditions were encountered the manganese and associated trace metals are believed to be leached from magmatic bodies by corrosive deep seated brines in southern israel and circulating meteoric waters in northern israel

precision of the current methods to measure the alkenone proxy u 37 k and absolute alkenone abundance in sediments results of an interlaboratory comparison study measurements of the u 37 k index and the absolute abundance of alkenones in marine sediments are increasingly used in paleoceanographic research as proxies of past sea surface temperature and haptophyte mainly coccolith bearing species primary productivity respectively an important aspect of these studies is to be able to compare reliably data obtained by different laboratories from a wide variety of locations hence the intercomparability of data produced by the research community is essential here we report results from an anonymous interlaboratory comparison study involving 24 of the leading laboratories that carry out alkenone measurements worldwide the majority of laboratories produce data that are intercomparable within the considered confidence limits for the measurement of alkenone concentrations however there are systematic biases between laboratories which might be related to the techniques employed to quantify the components the maximum difference between any two laboratories for any two single measurements of u 37 k in sediments is estimated with a probability of 95 to be c in addition the overall within laboratory precision for the u 37 k temperature estimates is estimated to be c 95 probability similarly from the analyses of alkenone concentrations the interlaboratory reproducibility is estimated at 32 and the repeatability is estimated at 24 the former is compared to a theoretical estimate of reproducibility and found to be excessively high hence there is certainly scope and a demonstrable need to improve reproducibility and repeatability of u 37 k and especially alkenone quantification data across the community of scientists involved in alkenone research

persistent suborbital climate variability in marine isotope stage 5 and termination ii new surface water records from two high sedimentation rate sites located in the western subtropical north atlantic near the axis of the gulf stream provide clear evidence of suborbital climate variations through marine isotope stage mis 5 persisting even into the warm peak of the interglaciation substage 5e we found that the amplitude of suborbital climate oscillations did not vary significantly for the whole of mis 5 implying that ice volume has little or no influence on the amplitude of suborbital climate variability in this region although some records suggest that longer suborbital variations 4 10 kyr during mis 5 are linked to deepwater changes none of the existing records is of sufficient resolution to assess if a linkage occurred for oscillations shorter than 4 kyr however when examined in conjunction with published data from the norwegian sea new evidence from the subpolar north atlantic suggests that coupled surface deepwater oscillations occurred during the penultimate deglaciation this supports the hypothesis that during glacial and deglacial times ocean ice interactions and deepwater variability amplify suborbital climate change at higher latitudes we suggest that during the penultimate deglaciation the north atlantic deepwater source varied between nordic sea and open north atlantic locations in parallel with surface temperature oscillations

geology of mount murphy volcano an 8 m y history of interaction between a rift volcano and the west antarctic ice sheet volcanic rocks glaciogenic sediments and recycled marine microfossils at mount murphy provide evidence for large scale fluctuations in the mass of the west antarctic ice sheet during neogene time mount murphy is a large shield volcano with an atypical structure its basal unit consists of alternating subaquatic and subaerial rock types through a stratigraphic interval of at least 300 m suggesting that ice level changed several times during shield building much larger changes are suggested by an outcrop of glacial lake sediment near the volcano summit 1 300 m above present ice level it contains an assemblage of recycled marine microfossils derived from marine basins in the interior of west antarctica they suggest multiple intervals of near complete deglaciation in west antarctica between about 24 and 3 5 ma the microfossils were probably deposited by meltwater from the ice sheet during a much higher stand of ice in late pliocene time it has long been suspected that the west antarctic ice sheet is unstable and vulnerable to greenhouse warming because it is grounded more than 1 000 m below sea level our results provide field evidence consistent with that proposal more than the west antarctic ice sheet may be involved however the nature of the evidence and timing of events at mount murphy are similar to the record in east antarctica suggesting continent wide synchroneity of the major glacial and interglacial intervals this conflicts with interpretations of marine data which suggest a shorter history for the west antarctic ice sheet and a more stable history for the entire ice sheet

african monsoons an immediate climate response to orbital insolation the croll milankovitch astronomical theory of climate1 3 has received strong support from the evidence of a linear climatic forcing by obliquity and precession although nonlinearity had to be assumed for eccentricity4 5 moreover interglacials have appeared to be controlled by the orbital insolation6 although a phase shift of 6 000 5 000 yr is seen between an astronomical climate index and terrestrial climate indicators dominated by the northern ice sheet dynamics climate proxy data of low latitudes are less directly dependent on the ice sheets here it is shown that during the past 464 000 yr african monsoons signalled by the east mediterranean sapropels were heaviest always and only when a northern summer monsoon index computed from the orbital variation of insolation reached maximum values this occurred during all the interglacials but also twice during glacial periods thus tropical aridity is not the single climatic pattern of glacial periods an immediate terrestrial climate response to orbital variations of insolation is established

magma water interactions in subaqueous and emergent basaltic in the subaqueous growth and emergence of a basaltic volcano clasts are formed by one or a combination of 1 explosive release of magmatic volatiles 2 explosive expansion and collapse of steam formed at magma water contact surfaces 3 explosive expansion of steam following enclosure of water in magma or entrapment of water close to magma and 4 cooling contraction these processes named respectivelymagmatic explosivity contact surface steam explosivity bulk interaction steam explosivity andcooling contraction granulation can be enhanced by mutual interaction and feedback the first three explosive processes are limited at certain water depths hydrostatic pressures and become increasingly vigorous at shallower levels the depth of onset of magmatic explosivity depends largely on juvenile volatile content it is up to 200 m for tholeiitic magmas and up to 1 km for alkalic magmas at the depth where formation of clastic deposits becomes predominant over effusion of lavas magmatic explosivity is subordinate to steam explosivity as a clast forming process the upward transition to accumulation of dominantly clastic deposits is not simply related to the onset of substantial exsolution of magmatic volatiles and can occur without it contact surface explosivity commonly requires initiation by a vigorous impact between magma and water and although no certain depth limit is known likelihood of such explosivity decreases rapidly with depth clast generation by bulk interaction explosivity appears to be restricted to depths much shallower than that of the critical pressure of water which in sea water is at about 3 km cooling contraction granulation can occur in any depth of water but at shallow levels may be replaced by contact surface explosivity during continuous eruption under water tephra can be ejected and deposited within a cupola of steam such that rapid quenching does not occur emergent volcanoes are characterized by distinctive steam explosive activity that results primarily from a bulk interaction between rapidly ascending magma and a highly mobile slurry of clastic material water and steam the water gets into the vent by flooding across or through the top of the tephra pile and violent explosions cease when this access is sealed the eruptions during emergence of surtsey and capelinhos typify the distinctive explosive activity the style and controls of which are different from those of maar volcanoes

complexity of holocene climate as reconstructed from a greenland ice core glaciochemical time series developed from summit greenland indicate that the chemical composition of the atmosphere was dynamic during the holocene epoch concentrations of sea salt and terrestrial dusts increased in summit snow during the periods 0 to 600 2400 to 3100 5000 to 6100 7800 to 8800 and more than 11 300 years ago the most recent increase and also the most abrupt coincides with the little ice age these changes imply that either the north polar vortex expanded or the meridional air flow intensified during these periods and that temperatures in the mid to high northern latitudes were potentially the coldest since the younger dryas event

basaltic subglacial sheet like sequences evidence for two types with different implications for the inferred thickness of associated ice abstract subglacially erupted volcanic sequences provide proxies for a unique range of palaeo ice parameters and they are potentially highly useful archives of palaeoenvironmental information particularly for pre quaternary periods they can thus be incorporated by climate and ice sheet modellers in the same way as other environmental proxies yet they remain largely under utilised basaltic volcanic sequences erupted subglacially consist empirically of two major types corresponding to eruptions under thick and thin ice respectively the latter are called subglacial sheet like sequences and only one generic type of sequence has been described so far however there is now evidence that there are at least two generic types with significantly different implications for interpretations of associated palaeo ice sheet thicknesses one type which is relatively well described is believed to be a diagnostic product of eruptions associated with a relatively thin glacial cover 1000 m eruptions that form the dalsheidi type of sequence commence with the injection and inflation of a sill along the ice bedrock interface such interface sills were predicted theoretically but had no known geological example until now subsequent evolution commonly involves floating of the ice cover catastrophic meltwater drainage and emplacement of widespread sheets of hyaloclastite as cohesionless mass flows and hyperconcentrated flows the water saturated hyaloclastite is characteristically intruded by apophyses sourced in the underlying interface sill eruptions are commonly not explosive until their later stages dalsheidi type deposits are outflow sequences probably linked to subglacial pillow volcanoes which in iceland were erupted along fissures they only provide an indication of minimum thicknesses of the associated overlying ice although theoretical considerations suggest substantial ice thicknesses in excess of 1000 m however they are likely to be characteristic products of eruptions under the thick west antarctic ice sheet but are currently inaccessible such eruptions may be capable of destabilising that ice sheet

on the timing and mechanism of millennial scale climate variability during the last glacial cycle the demonstration that natural climate variability during the last glacial cycle shifted rapidly between remarkable extremes has dramatically revised the understanding of climate change to further advance our understanding research continues into the timings geographic distribution and nature of the millennial scale climate extremes and into the mechanisms for intra and inter hemispheric transmission of variability through the climate ocean system complementing the traditional definition of the timings of millennial scale climate variability from ice core 18o records we here further narrow down the temporal constraints by determining statistically significant anomalies in the major ion series of the gisp2 ice core this exercise offers an objective definition of the timing of climatic anomalies in northern hemisphere palaeoclimate proxy records of the last 110 000 years that significantly improves the potential for inter calibration of ice core tuned chronostratigraphies we then present a process oriented synthesis of proxy records from the northern hemisphere this leads to a conclusion that the dansgaard oeschger d o style fluctuations in these records are virtually in phase since all fall within a clear atmospheric pattern of concerted relative dominance shifts between polar westerly dominated winter type conditions and tropical monsoon dominated summer type conditions finally we speculate on a monsoon related mechanism that could help explain the anomalously long duration of d o interstadials 12 8 and 1 which coincided with cooling trends in antarctic records

evidence for general instability of past climate from a 250 kyr ice core record recent results1 2 from two ice cores drilled in central greenland have revealed large abrupt climate changes of at least regional extent during the late stages of the last glaciation suggesting that climate in the north atlantic region is able to reorganize itself rapidly perhaps even within a few decades here we present a detailed stable isotope record for the full length of the greenland ice core project summit ice core extending over the past 250 kyr according to a calculated timescale we find that climate instability was not confined to the last glaciation but appears also to have been marked during the last interglacial as explored more fully in a companion paper3 and during the previous saale holstein glacial cycle this is in contrast with the extreme stability of the holocene suggesting that recent climate stability may be the exception rather than the rule the last interglacial seems to have lasted longer than is implied by the deep sea specmap record4 in agreement with other land based observations5 6 we suggest that climate instability in the early part of the last interglacial may have delayed the melting of the saalean ice sheets in america and eurasia perhaps accounting for this discrepancy

deglaciation of pope glacier implies widespread early holocene ice sheet thinning in the amundsen sea sector of antarctica abstract the amundsen sea sector of the antarctic ice sheet presently dominates the contribution from antarctica to sea level rise several large ice streams that currently drain the sector have experienced rapid flow acceleration grounding line retreat and thinning during the past few decades however little is known of their longer term millennial scale retreat history despite the reliance of several ice sheet and glacial isostatic adjustment models on such data for improving sea level prediction from this critical region this study investigates the timing and extent of surface lowering of one of those ice streams pope glacier since the last glacial maximum lgm using glacial geological evidence for former ice cover we present a new deglacial chronology for the glacier derived from surface exposure dating of glacially deposited cobbles and ice scoured bedrock from mount murphy and its surrounding peaks cosmogenic 10be exposure ages from 44 erratic cobbles and 5 bedrock samples and in situ 14c exposure ages from one erratic and 8 bedrock samples are predominantly in the range 5 5 16 ka although 10be inheritance from prior exposure is prevalent in some erratics and probably all bedrock samples none of the ages pre date the lgm from these results we infer that the surface of pope glacier lowered by 560 m during the early to mid holocene 9 6 ka at an average rate of 0 13 0 09 0 04 m yr 1 the lowering coincided with a period of enhanced upwelling of warm circumpolar deep water onto the continental shelf in the region a reduction in buttressing facilitated by such upwelling by an ice shelf that is thought to have spanned the embayment until 10 6 cal kyr bp could have triggered simultaneous early holocene thinning of pope glacier and glaciers elsewhere in the amundsen sea embayment

morphometric study of pillow size spectrum among pillow lavas measurements of h and v dimensions in the horizontal and vertical directions of pillows exposed in vertical cross section were made on 19 pillow lavas from the azores cyprus iceland new zealand tasmania the western usa and wales the median values of h and v plot on a straight line that defines a spectrum of pillow sizes having linear dimensions five times greater at one end than at the other basaltic toward the small size end and andesitic toward the large size end the pillow median size is interpreted to reflect a control exercised by lava viscosity pillows erupted on a steep flow foot slope in lava deltas can however have a significantly smaller size than pillows in tabular pillowed flows inferred to have been erupted on a small depositonal slope indicating that the slope angle also exercised a control pipe vesicles generally abundant in the tabular pillowed flows and absent from the flow foot pillows have potential as a paleoslope indicator pillows toward the small size end of the spectrum are smooth surfaced and grew mainly by stretching of their skin whereas disruption of the skin and spreading were important toward the large size end disruption involved increasing skin thicknesses with increasing pillow size and pillows toward the large size end are more analogous with toothpaste lava than with pahoehoe and are inferred from their thick multiple selvages to have taken hours to grow pseudo pillow structure is also locally developed an example of endogenous pillow lava growth that formed intrusive pillows between normal pillows is described from sicily isolated pillow like bodies in certain andesitic breccias described from iceland were previously interpreted to be pillows but have anomalously small sizes for their compositions it is now proposed that they may lack an essential attribute of pillows namely the development of bulbous forms by the inflation of a chilled skin and are hence not true pillows para pillow lava is a common lava type in the flow foot breccias it forms irregular flow sheets that are locally less than 5 cm thick and failed to be inflated to pillows perhaps because of an inadequate lava supply rate or too high a flow velocity

correlation between rate of sea level change and frequency of explosive volcanism in the mediterranean volcanic activity has frequently been linked to quaternary environmental change either by driving climate modification1 2 or in response to environmental changes3 although a link has been established between large explosive eruptions and small 0 5 c brief 1 2 years falls in global temperatures4 both the evidence and mechanisms responsible for longer episodes of eruption induced planetary cooling remain questionable1 2 5 6 in contrast recent research based on ice core data suggests that rapid climate changes during the past 110 000 years increased explosive volcanic activity7 here we present a statistical analysis relating the frequency of explosive activity of mediterranean volcanoes based on dated8 9 10 11 tephra layers in deep sea sediment cores to the rate of late quaternary sea level change the nonlinear correlation between the two is tentatively explained in terms of dynamic responses of the volcanoes to stress related influences on various spatial scales the correlation supports a mechanism or mechanisms by which the climate driven growth and decay of large ice sheets can influence the eruptive chronologies of distant volcanic edifices via changes in global sea level