a 4500 year proxy climate record from peatlands in the north of ireland the identification of widespread summer drought phases abstract mid to late holocene high resolution testate amoebae derived water table reconstructions from two peatlands in the north of ireland are presented the proxy climate records are dated and correlated using a combination of ams 14 c dating spheroidal carbonaceous particles and tephrochronology the reconstructions start prior to the hekla 4 tephra isochron 2395 2279 bc and thus span the last 4500 years the records are compiled by the process of tuning within chronological errors standardisation and stacking comparisons are made to existing palaeoclimate records from peatlands in northern britain and ireland and the compiled lake level record for mid latitude europe four coherent dry phases are identified in the records at ca 1150 800 bc 320 bc ad 150 ad 250 470 and ad 1850 2000 recent research has shown that peat derived water table reconstructions reflect summer water deficit and therefore the dry phases are interpreted as periods with a higher frequency and or greater magnitudes of summer drought these drought phases occur during periods of relatively low 14 c production which may add support to the hypothesis of persistent solar forcing of climate change during the holocene any relationship with the north atlantic stacked drift ice record is less clear

the mjauvotn tephra and other holocene tephra horizons from the faroe islands a link between the icelandic source region the nordic seas and the european continent six different tephra horizons were found in peat and lacustrine sediments on the faroe islands in the north atlantic their geochemistry showed that they were of icelandic origin three of these can be correlated with previously described tephra horizons from the faroe islands the saksunarvatn tephra c 9000 bp the hekla 4 c 3800 bp and hekla selsund c 3600 bp a previously unrecorded basaltic tephra dated to c 5700 5300 bp was found in two lacustrine successions this horizon is named the mjauvotn tephra after mjauvotn lake on the island of streymoy two further tephras were recorded the basaltic phase of the landnam tephra viia c ad 870s and the rhyolitic tjornuvk tephra these were found in sediments deposited shortly after the first phase of human settlement at tjornuvik which is ams dated to ad 675 861 calibrated age the faroe islands are an important link between the volcanic sources on iceland and the established tephrochronological frameworks on the british isles scandinavia and germany their position within a sensitive region of the northeastern branch of the north atlantic drift make the faroe islands ideal for registering climate changes during the holocene the establishment of a modern tephrochronology may provide a tool for more precisely dating and correlating regional climate events in and around the nordic seas

late holocene ultra distal cryptotephra discoveries in varved sediments of lake żabinskie ne poland abstract varved annually laminated lake sediments provide valuable archives for ultra distal tephra preservation and at the same time allow the precise dating of volcanic eruptive events we used a high precision varve chronology from lake abinskie in ne poland and epma glass chemical data to identify cryptotephra from three large scale late holocene eruptions from european and northern american volcanoes the white river ash eastern lobe wrae eruption from mount churchill alaska 833 850 ce a tentative finding of the glen garry eruption of the askja volcano iceland 1966 2210 cal a bp and an yet undefined eruption from furnas volcano azores the varve age of 863 903 ce of the alaskan wrae cryptotephra in lake abinskie is slightly younger than the proximal radiocarbon date and the annual layer estimate of the distal ad860b correlative in the greenland ngrip ice core but is within 14c dating uncertainties of distal tephra findings in the irish peat record the varve ages of the glen garry and furnas tephras in lake abinskie provide a minimum age at 1991 cal a bp 41 bce all three cryptotephra findings represent their easternmost occurrences from the volcanic source and hence considerably extend existing tephra dispersal maps

towards a holocene tephrochronology for the faroe islands north atlantic abstract the faroe islands hold a key position in the north atlantic region for tephra studies due to their relative proximity to iceland several tephras have been described over the last 50 years in peat and lake sediment sequences including the type sites for the saksunarvatn and mjauvotn tephras here we present a comprehensive overview of holocene tephras found on the faroe island in total 23 tephra layers are described including visible macrotephras such as the saksunarvatn and hekla 4 tephras and several cryptotephras the importance of tephras originally described from the faroe islands is highlighted and previously unpublished results are included in addition full datasets for several sites are published here for the first time the saksunarvatn ash now considered to be the result of several eruptions rather than one major eruption can be separated into two phases on the faroe islands one early phase with two precursor eruptions with lower mgo concentrations 4 5 5 0 wt than the main eruption and a later phase with higher mgo concentrations 5 5 6 0 wt including the visible saksunarvatn ash the tjornuvik tephra previously considered to be a primary deposit is now interpreted as a reworked tephra with material from at least two middle holocene eruptions of hekla several of the tephras identified on the faroe islands provide useful isochrons for climate events during the holocene

do peatlands or lakes provide the most comprehensive distal tephra records abstract despite the widespread application of tephra studies for dating and correlation of stratigraphic sequences tephrochronology questions remain over the reliability and replicability of tephra records from lake sediments and peats particularly in sites 1000 km from source volcanoes to address this we examine the tephrostratigraphy of four pairs of lake and peatland sites in close proximity to one another

tephrological implications of beam size sample size effects in electron microprobe analysis of glass shards this paper concerns the potential consequences of varying procedures for the determination of tephra geochemistry by electron microprobe application of electron probe microanalysis to tephrostratigraphical methods has increasingly facilitated the resolution and refinement of quaternary chronology associated with records of proxy environmental or proxy climatic change the geographical range over which tephras are recovered has expanded significantly with the identification and analysis of crypto or hidden tephras in areas far removed from tephra sources these tephras are dominated by glass shards which in many distal environments may be either small in size m or may be highly pumiceous with low glass void ratios and thin 10 m shard walls we demonstrate that reducing the size of the electron beam used to analyse shard geochemistry cannot be used reliably to permit analysis of thin glass walls this approach distorts the geochemical data creating analytical differences that may generate inappropriate tephrogeochemical fingerprints additional distortion of the geochemical fingerprint in the form of hybrid analyses may be encountered in glass fragments containing micron sized crystalline phases such as feldspar copyright 2001 john wiley sons ltd

a new early holocene cryptotephra from northwest scotland clarification of the temporal relationships amongst records of environmental change is dependent on accurate timescales event markers such as tephra layers are extremely important for constraining chronologies and providing tie points in this report we present evidence of a previously unknown early holocene icelandic cryptotephra from a lake in northern scotland the an druim tephra the calibrated radiocarbon age of 9560 cal yr bp for this new cryptotephra makes it an important addition to the suite of cryptotephras now recorded from the last glacial termination and early holocene in northwest europe in addition we report evidence in support of a younger borrobol tephra from lateglacial sediments of allerod age copyright 2005 john wiley sons ltd

on the extraordinary katabatic winds of adelie land the winds observed in adelie land eastern antarctica are the strongest observed anywhere on earth close to sea level e g cape denison measured a mean annual wind speed of about 20 m s 1 some historic data from the area are available however such measurements were carried out at different places for different time periods hence in december 1992 we placed four automatic weather stations along the coast of adelie land two in the maximum wind jet port martin and cape denison and one on each side of this jet d 10 close to dumont d urville and penguin point respectively we obtained about three months of good data as on march 25 1993 a strong storm destroyed three of the four wind sensors wind velocities are discussed as a function of other meteorological parameters further the interrelationships between the stations are described some of the findings are 1 the very high wind speeds reported earlier this century are in agreement with our measurements the wind directional constancy is high 2 historic measurements reported cape denison to be the windiest station not only for antarctica but also close to sea level for planet earth again our measurements are in agreement 3 very strong wind speeds have a more down slope direction than weaker ones 4 the general atmospheric pressure gradient enhanced or inhibited the gravity flow this is especially well pronounced in summer and 5 in summer above normal pressure is correlated with above normal temperatures in fall the opposite holds true

holocene tephrostratigraphy of varved sediment records from lakes tiefer see ne germany and czechowskie n poland a detailed holocene tephrostratigraphic framework has been developed for two predominately varved lake sediment sequences from ne germany lake tiefer see and central n poland lake czechowskie a total of thirteen tephras and cryptotephras of icelandic provenance were detected and chemically fingerprinted in order to define correlatives and to integrate known tephra ages into the sediment chronologies out of these three cryptotephras askja ad1875 askja s and h asseldalen were identified in both records thus allowing a detailed synchronization of developing high resolution palaeoenvironmental proxy data the early holocene saksunarvatn ash layer and the middle holocene lairg b and hekla 4 cryptotephras in lake tiefer see are further important anchor points for the comparison with other high resolution palaeoclimate records in central and northern europe tentative correlations of cryptotephras have been made with a historical basaltic grimsv otn eruption ad890 e ad856 and three late holocene rhyolitic eruptions including the 2 1 ka glen garry and two unknown high silicic cryptotephras of probably icelandic provenance 1 9 cal ka bp

ash layers from iceland in the greenland grip ice core correlated with oceanic and land sediments four previously known ash layers ash zones i and ii saksunarvatn and the settlement layer all originating in iceland have been identified in the central greenland ice core grip this correlation of the ash between the different environments is achieved by comparison of the chemical composition of glass shards from the ash this establishes and confirms detailed correlations between the different types of depositional records and the absolute dating of the younger part of the ice core by counting annual layers dates the eruptions accurately a precise connection with dates obtained by14c beyond the range of dendrochronology is established which provides an excellent confirmation of230th 234u dates from corals four additional icelandic ash layers have also been identified in the core but not yet correlated with known ash deposits

dates of holocene icelandic volcanic eruptions from tephra layers in irish peats tephra from historic and prehistoric eruptions of oraefajokull and hekla iceland have been found in irish peats using a series of stratigraphically related high precision radiocarbon measure ments the date of a known age eruption has been satisfactorily estimated based on the same techniques the calendrical date of the hekla 4 eruption has been estimated as 2310 20 bc

age geochemistry and distribution of the mid holocene hekla s kebister tephra the middle holocene hekla s kebister tephra originates in the hekla volcanic system on sw iceland the distal distribution of the tephra includes the faroe islands shetland and central sweden indicating a main dispersal towards the east the chemical composition of the tephra follows the pattern of other major eruptions of hekla and ratios between selected oxides may in some cases allow separation from other major holocene tephras from hekla tephra from the plinian phase dominates in eastern sites while tephra also from later phases is found in the faroe sites wiggle matching of radiocarbon dates around the tephra in a swedish peat bog suggests an age around 3720 cal yr bp 3750 3700 cal yr bp which is in accordance with previous attempts to date this tephra this is within a period with significant climate changes in nw europe and opens possibilities for exact comparisons of peat and lake sediment records from different geographical areas

a new high resolution holocene tephra stratigraphy in eastern iceland improving the icelandic and north atlantic tephrochronology a new and improved holocene tephra stratigraphy and tephrochronological framework for eastern and northern iceland is presented investigations of a sediment sequence from lake logurinn have revealed a comprehensive tephra record spanning the last 10 200 years a total of 157 tephra layers have been identified whereof 149 tephra layers have been correlated to its source volcanic system using geochemistry stratigraphy and age fifteen layers have chemical composition of two affinities that possibly represent two very closely spaced eruptions thus these 157 tephra layers are believed to represent 172 explosive eruptions nineteen tephra marker layers have been identified in the lake logurinn record g1922 a1875 v1477 v1410 h1636 k1625 o1362 g1354 k1262 v874 hrafnkatla sn 1 grakolla hy h3 h4 ho ll1755 and reitsvik 8 tephra markers new potential tephra markers are the silicic askja l 9400 cal bp the low titanium basalt layers ll 1774 10 150 cal bp and ll 1755 9990 cal bp assigned to veidivotn bardarbunga and the tephra layers ll 1527 8 7850 cal bp ll 911 2 2370 cal bp ll 908 4 2350 cal bp ll 781 9 1930 cal bp ll 644 4 1480 cal bp not yet correlated to a source volcanic system a silicic tephra marker layer reitsvik 8 correlated to the fosen tephra in norway has been identified in lake logurinn the lake logurinn tephra record has been connected and integrated with the icelandic terrestrial tephrochronology and stratigraphy through 102 tephra layers the marine tephra stratigraphy through 39 layers and overseas through 9 tephra layers this record is the first high resolution tephra stratigraphical and chronological framework for the holocene in eastern iceland as well as the most detailed and continuous record and has considerable potential to serve as a key section or a stratotype for the holocene in eastern iceland and the north atlantic

the chronology of abrupt climate change and late upper palaeolithic human adaptation in europe abstract this paper addresses the possible connections between the onset of human expansionineuropefollowingthelastglacialmaximum andthetimingofabruptclimatewarmingattheonsetof thelateglacial bo lling allerod interstadial thereare opposing views as towhether ornot humanpopulations and activities were directly forced by climate change based on different comparisonsbetween archaeological and environmental data we review the geochronological assumptions andapproaches on which data comparisons have been attempted in the past and argue that theuncertainties presently associated with age models based on calibrated radiocarbon dates precluderobust testing of the competing models particularly when comparing the data to non radiocarbon basedtimescalessuchasthegreenlandicecorerecords thepaperconcludeswithsomesuggestionsastothestepsthatwillbenecessaryifmorerobusttestsofthemodelsaretobedevelopedinthefuture copyright 2006 john wiley sons ltd keywords lateglacial radiocarbon calibration intcal04 lake suigetsu palaeotemperature reconstruction human adaptation tephrochronology

assessing the impact of volcanic activity on mid holocene climate in ireland the need for replicate data analyses of pollen tephra mineral input and degree of peat humification from three neighbouring raised peat profiles at corlea central ireland covering the period of the deposition of a tephra

tephrostratigraphy of an loch mor inis oirr western ireland implications for holocene tephrochronology in the northeastern atlantic region twelve definable cryptotephra layers younger than c 8600cal bp are reported from lacustrine core material taken from an loch mor inis oirr aran islands western ireland the geochemistry of these shard layers which represent more holocene tephras than previously geochemically characterized from any european site outside the proximal volcanic influence of italy or iceland is presented of these tephras four may correlate with known iceland derived tephra horizons vo 1477 hi lairg a and h5 one appears to have two possible named correlatives hoy lairg b at sluggan bog n ireland another has a plausible correlative ad 860a but two others represent icelandic tephras apparently not previously reported on iceland itself including a tephra that has geochemistry very similar to hl ad 1104 but which dates to c cal ad 840 four tephras that date from the period c ad 40 1400 have a distinct geochemical signature that relates to jan mayen 750km to the northeast of iceland and some 1800km distant from an loch mor the results contribute substantially to the chronology of the sediments from an loch mor and at the international level to the tephrostratigraphy of the northeast atlantic region the well attested icelandic h4 tephra from a hekla eruption of c 4260cal bp was not recorded it is suggested that an loch mor lies south of its recordable distribution in this part of the northeast atlantic region taken together with work at other sites the findings point to a wealth of potential tephra isochrons in holocene deposits of the northeast atlantic seaboard it is clear also that calcareous lake sediments can be as fruitful a source of tephras as peats potential problems relating to dating and geochemical fingerprinting of tephra layers in individual sites are highlighted with reference to the lairg tephras as recorded in scotland and northern ireland and to the hoy tephra that has been described from orkney

seven tephra isochrones in scotland this paper reports the presence and geochemical characteristics of seven separate tephras in scotland that fell in ad 1510 and about 450 bp 2100 bp 3600 bp 3830 bp 5600 bp and around 6000 bp the results come from 14 peat bogs spread throughout the highlands and islands where 26 tephra deposits have been characterized using over 400 grain discrete electron probe micro analysis firstly tephras are identified and defined by major element characteristics at a reference site secondly tephras are linked between sites on the basis of geochemistry and dated informal names based on british sites are suggested for tephras not yet linked to precise sources in iceland despite some apparent variation in colour all analysed grains in these seven deposits are silicic or intermediate in composition sio2 57 this phenomenon does not appear to be an artifact of preservation for two reasons first small 40 m basic glass shards in peat bogs in northern iceland are found to have undergone minimal alte

an overview of distal tephrochronology in northern europe during the last 1000 years several tephra layers from the last millennium have been identified in distal peat and lake sediment sequences in northern europe forming a framework of volcanic events of great value for palaeoenvironmental investigations most of the tephras within this framework have an origin in iceland but distal layers from jan mayen have also been identified the predominant transport pathway in an easterly southeasterly direction has led to the deposition of these tephras in a number of terrestrial deposits in northern europe ash from silicic eruptions 63 sio2 dominate at these sites even though many of the documentary records in distal areas report tephra fall from several basaltic eruptions here we provide an overview of the distribution shard concentration and geochemistry of these tephras to highlight the most important isochrones for addressing key dating issues in particular three horizons hekla 1 ad 1104 oraefajokull ad 1362 and askja ad 1875 are found at a number of different locations in northern europe and as such are valuable tie points for improving and validating chronological models and for synchronisation of records spanning the last 1000 years in addition we present new data identifying tephra from the grimsvotn volcanic system within the lomonosovfonna ice cap on svalbard demonstrating that some tephras have been transported 2000 km to as far north as 798 n along a northeasterly trajectory this discovery highlights the potential for utilising tephrochronology as a correlation tool for palaeoarchives located in more northerly areas and the complex nature of fall out from different eruptions copyright 2009 john wiley sons ltd

centennial scale climate change in ireland during the holocene we examine mid to late holocene centennial scale climate variability in ireland using proxy data from peatlands lakes and a speleothem a high degree of between record variability is apparent in the proxy data and significant chronological uncertainties are present however tephra layers provide a robust tool for correlation and improve the chronological precision of the records although we can find no statistically significant coherence in the dataset as a whole a selection of high quality peatland water table reconstructions co vary more than would be expected by chance alone a locally weighted regression model with bootstrapping can be used to construct a best estimate palaeoclimatic reconstruction from these datasets visual comparison and cross wavelet analysis of peatland water table compilations from ireland and northern britain show that there are some periods of coherence between these records some terrestrial palaeoclimatic changes in ireland appear to coincide with changes in the north atlantic thermohaline circulation and solar activity however these relationships are inconsistent and may be obscured by chronological uncertainties we conclude by suggesting an agenda for future holocene climate research in ireland

the spatial distribution of holocene cryptotephras in north west europe since 7 ka implications for understanding ash fall events from icelandic eruptions abstract we present distribution maps for all cryptotephras distal volcanic ash layers younger than 7 ka that have been reported from three or more lakes or peatlands in north west europe all but one of the tephras originates from iceland the exception has been attributed to jan mayen we find strong spatial patterning in tephra occurrence at the landscape scale most but not all of the tephra occurrences are significantly spatially clustered which likely reflects atmospheric and weather patterns at the time of the eruptions contrary to expectations based on atmospheric modelling studies tephras appear to be at least as abundant in ireland and northern scotland as in scandinavia rhyolitic and other felsic tephras occur in lakes and peatlands throughout the study region but andesitic and basaltic tephras are largely restricted to lake sites in the faroe islands and ireland explanations of some of these patterns will require further research on the effects of different methodologies for locating and characterizing cryptotephras these new maps will help to guide future investigations in tephrochronology and volcanic hazard analysis

investigation of the environmental impact of remote volcanic activity on north mayo ireland during the mid holocene seven layers of microscopic tephra have been detected in ombrotrophic peat from western ireland a radiocarbon chronology suggests that two of the tephra layers were deposited around 4000 bp pollen fungal spores and testate amoebae have been analyzed from the peat immediately above and below the tephra layers these analyses provide information of changes in the landscape surrounding the bog and as well as conditions on the bog surface analysis of rates of change in these data has been employed to investigate the relative magnitude of environmental changes at the time of tephra deposition tephra deposition occurred at least 100 years after a major decline in pinus pollen and coincides with fairly stable conditions in the terrestrial environ ment more significant changes on the bog surface indicative of wetter conditions are associated with the timing of tephra deposition

evidence for the occurrence of vedde ash in sweden radiocarbon and calendar age estimates a tephra layer of rhyolitic composition has been recorded in sediments from lake madtjarn southwestern sweden geochemical analyses have shown that the tephra is identical to the rhyolitic component of the middle younger dryas vedde ash a series of ams radiocarbon measurements places the radiocarbon age of the tephra within a 14c plateau at 10 400 10 300 14c y bp based on a linear younger dryas sedimentation rate and assumptions about the apparent synchroneity of changes in lake sediments tree rings and ice core records the calendar year age of the tephra concentrations is estimated at 12 045 11 975 yr bp which accords well with the age of the equivalent tephra in the grip core 1998 john wiley sons ltd

late glacial and holocene palaeoceanography of the north icelandic shelf high resolution gravity cores and box cores from the north icelandic shelf have been studied for palaeoceanographic history based on lithological and biostratigraphical foramin iferal data results from two outer shelf cores covering the last 13 6 k 14 c yr bp are presented in this paper the sediments accumulated in north south trending basins on each side of the kolbeinsey ridge at water depths of ca 400 m sedimentation rates up to 1 5 m kyr 1 are observed during the late glacial and holocene the vedde and saksunarvatn tephras are present in the cores as well as the hekla 1104 a new tephra kol gs 2 has been identified and dated to 13 4 k 14 c yr bp and another tephra geochemically identical to the borrobol tephra has been found at the same level at present the oceanographic polar front is located on the north icelandic shelf which experiences sharp oceanographic surface boundaries between the cold east icelandic current and the warmer irminger current past changes in sedimentological and biological processes in the study area are assumed to be related to fluctuations of the polar front the area was deglaciated before ca 14 kyr bp but there is evidence of ice rafting up to the end of the gs 1 greenland stadial 1 younger dryas period increasing again towards the end of the holocene foraminiferal studies show a relatively strong gs 2 pre 13 kyr bp palaeo irminger current followed by severe cooling and then by unstable conditions during the remainder of the gi 1 greenland interstadial 1 bolling allerod and gs 1 younger dryas another cooling event occurred during the preboreal before the holocene current system was established at about 9 kyr bp after a climatic optimum between 9 and 6 kyr bp the climate began to deteriorate and fluctuate copyright 2000 john wiley sons ltd

geochemistry of historical age silicic tephras in iceland the major element chemistry of nine silicic tephras of historical age from iceland is assessed as a key step in the development of the recent tephrochronology of the north atlantic region the tephras include the largest such layers produced by each of the five central volcanoes hekla o raefajokull eyjafjallajokull torfajokull and askja since the ninth century ad h 1104 o1362 e 1821 landnam tephra c 870 a 1875 and four other tephras h 1158 h 1510 h 1947 o1727 the determination of grain discrete major element chemistry of the glass fraction is a fundamental stage in the identification and correlation of tephra and allows links to be made between icelandic source areas with precise dating evidence and distal deposits elsewhere in the north atlantic region although major element data can be used to discriminate between tephra layers produced by the different central volcanoes on its own it cannot be used to identify all the holocene layers produc

calendar year ages of three mid holocene tephra layers identified in varved lake sediments in west central sweden three intermediate to rhyolitic icelandic holocene tephra horizons hekla 3 kebister and hekla 4 have been identified in annually laminated varved lake sediments in the province of varmland west central sweden calendar year ages were obtained from varve counts and are supported by additional c 14 dating based on terrestrial plant macrofossils the varve ages of the three tephras are 3295 95 cal bp hekla 3 4030 103 cal bp kebister and 4390 107 cal bp hekla 4 the varve age of hekla 3 refines the former calibrated 14 c age based on studies in the british isles and germany considering the age error estimates associated with the varve chronology and calibrated c 14 ages the ages of kebister and hekla 4 are in agreement with former studies thus the age difference between kebister and hekla 4 is estimated to be ca 400 40 varve years formally estimated to ca 200 c 14 years between hekla 3 and hekla 4 to ca 1135 55 varve years formally estimated to ca 1100 calibrated c 14 years and between hekla 3 and kebister 708 20 varve years less

thin tephra layers in peat revealed by x radiography x radiography has been found to provide a rapid economical non destructive method of locating very thin fine grained tephra of icelandic origin in scottish peats tephra layers form time parallel marker horizons or isochrones that are of great archaeological significance because they cover large areas offer precise chronological control for associated material and occur at times of significant cultural and environmental changes not all of the discrete deposits of recent volcanic fallout in scotland are sufficiently dense to show clearly on x radiographs but those which do provide particularly clear easily located marker horizons with many applications in palaeoenvironmental studies the tephra layer in caithness produced by fallout from a c 4000 by eruption of hekla provides a particularly good example of the use of x radiography to locate volcanic ash the method also reveals other structures of archaeological and palaeoenvironmental significance butler 1992 journal of archaeological science 19 151 161

a 9000 year old ash bed on the faroe islands abstract radiocarbon datings of the saksunarvatn ash bed on the faroe islands indicate an age of 9000 9100 yr b p the saksunarvatn ash bed differs geochemically from both ash zone 1 in the north atlantic and the vedde ash bed of norway and the norwegian sea all mentioned ashes are assumed to originate from iceland the vedde ash has been dated at 10 600 60 yr b p consequently the saksunarvatn and vedde ash beds provide an opportunity for precise dating of events around the pleistocene holocene boundary in marine cores especially from the region where the two plumes overlap

towards a tephrochronology for the holocene of the north of ireland discrete layers of tephra have been found in both raised and blanket bogs in the north of ireland some of the layers have been identified to an icelandic source and in two cases specific eruptions of known radiocarbon age are suggested nine layers spanning the holocene are replicated in three lowland raised bogs one of the major layers has also been identified at a number of sites in two separate upland blanket peat systems and in a lake sediment

selective concentration and enumeration of tephra shards from lake sediment cores this paper describes a technique for the enumeration of tephra shards from lake sediment cores whereby approximately 85 of unwanted sediment fractions organic matter biogenic silica carbonates are removed by selective stepwise chemical attack the order of 100 samples can be prepared simultaneously in a modest sized water bath and the recovery rate of the technique is greater than 90 the procedure is appli cable to all lake sediment types

mild little ice age and unprecedented recent warmth in an 1800 year lake sediment record from svalbard the arctic region is subject to a great amplitude of climate variability and is currently undergoing large scale changes due in part to anthropogenic global warming accurate projections of future change depend on anticipating the response of the arctic climate system to forcing and understanding how the response to human forcing will interact with natural climate variations the svalbard archipelago occupies an important location for studying patterns and causes of arctic climate variability however available paleoclimate records from svalbard are of restricted use due to limitations of existing climate proxies here we present a sub decadal to multidecadal scale record of summer temperature for the past 1800 yr from lake sediments of kongressvatnet on west spitsbergen svalbard based on the first instrumental calibration of the alkenone paleothermometer the age model for the high arctic lake sediments is based on 210 pb plutonium activity and the first application of tephrochronology to lake sediments in this region we find that the summer warmth of the past 50 yr recorded in both the instrumental and alkenone records was unmatched in west spitsbergen in the course of the past 1800 yr including during the medieval climate anomaly and that summers during the little ice age lia of the 18 th and 19 th centuries on svalbard were not particularly cold even though glaciers occupied their maximum holocene extent our results suggest that increased wintertime precipitation rather than cold temperatures was responsible for lia glaciations on svalbard and that increased heat transport into the arctic via the west spitsbergen current began ca a d 1600

the presence of holocene cryptotephra in wales and southern england this research was undertaken while e w held a nerc funded doctoral training grant ne k500847 1 this research was also supported by a young research workers award to e w from the quaternary research association

volcanism and the greenland ice cores the tephra record abstract in recent years increased awareness of the considerable potential offered by tephrochronology in palaeoclimatic studies has fuelled a renewed interest in the tephra record preserved within the greenland ice cores this renewal has occurred in tandem with the development of continuous flow analysis techniques which provide high resolution volcanic aerosol records these chemical records are of considerable value for identifying tephra horizons composed of glass shards and also provide the basis for a new high precision ice core timescale thus allowing ages to be assigned to volcanic events tephra horizons of glass shards in the ice cores play a critical role for 1 testing and building chronological frameworks for the ice cores and other sequences 2 synchronising disparate palaeoclimatic sequences and testing phase relationships 3 atmospheric pathway reconstruction and 4 verifying the source of volcanic aerosol peaks here we review the results of over 25 years of research into tephra horizons in the grip gisp2 and ngrip cores we provide high precision ages for horizons based on recently developed timescales and draw together geochemical characterisations of the products of 45 volcanic events deposited on the greenland ice sheet and identified in the cores there is a clear disparity between the number of volcanic aerosol peaks and the number of tephra horizons of glass shards identified thus far however this synthesis highlights the critical role of the greenland ice cores firstly in the reconstruction of the history of icelandic volcanic eruptions and secondly the considerable value of some tephra horizons in facilitating the correlation of these key climatic archives to north atlantic marine sequences other noteworthy issues include the potential of these cores to preserve tephra horizons from more distal volcanic sources such as north america to resolve the debate surrounding the thera eruption and the observation that some tephra horizons are preserved within the ice without coeval volcanic aerosol signals

the volcanic eruption on jan mayen january 1985 interaction between a volcanic island and a fracture zone abstract an eruption started on jan mayen on 6 january 1985 it lasted only 35 40 hours and discharged about 7 million m3 of magma an earthquake swarm accompanied the eruption with individual quakes reaching magnitude 5 the volcanic fissure that opened strikes about midway between the strike of the jan mayen fracture zone 25 n of w and the general trend of the island and its volcanic features sw ne this fact the strong earthquakes and compositional features all suggest that it was an eruption from a leaky fracture zone rather than from the jan mayen magma system proper

traces of volcanic ash from the mediterranean iceland and north america in a holocene record from south wales uk a tephra record is presented for a sediment core from llyn llech owain south wales spanning the early to mid holocene seven cryptotephra deposits are discovered with three thought to correlate with known eruptions and the remaining four considered to represent previously undocumented events one deposit is suggested to correlate with the 6 9 cal ka bp lairg a tephra from iceland whereas more distant sources are proposed as the origin for two of the tephra deposits a peak of colourless shards in early holocene sediments is thought to tentatively correlate with the 9 6 cal ka bp fondi di baia tephra campi flegrei and a second cryptotephra is tentatively correlated with the 3 6 cal ka bp aniakchak cfe ii tephra alaska the fondi di baia tephra has never been recorded beyond proximal sites and its discovery in south wales significantly extends the geographical distribution of ash from this eruption the remaining four cryptotephra deposits are yet to be correlated with known eruptions demonstrating that our current understanding of widespread tephra deposits is incomplete this new tephra record highlights the potential for sites at more southerly and westerly locations in northwest europe to act as repositories for ash from several volcanic regions

a 7000 yr perspective on volcanic ash clouds affecting northern europe the ash cloud resulting from the a d 2010 eruption of eyjafjallajokull in iceland caused severe disruption to air travel across europe but as a geological event it is not unprecedented analysis of peats and lake sediments from northern europe has revealed the presence of microscopic layers of icelandic volcanic ash tephra these sedimentary records together with historical records of holocene ash falls demonstrate that icelandic volcanoes have generated substantial ash clouds that reached northern europe many times here we present the first comprehensive compilation of sedimentary and historical records of ash fall events in northern europe spanning the past 7000 yr ash fall events appear to have been more frequent in the past 1500 yr it is unclear whether this reflects a true increase in eruption frequency or dispersal or is an artifact of the records or the way in which they have been generated in the past 1000 yr volcanic ash clouds reached northern europe with a mean return interval of 56 9 yr the range of return intervals is between 6 and 115 yr probabilistic modeling using the ash records for the last millennium indicates that for any 10 yr period there is a 16 probability of a tephra fallout event in northern europe these values must be considered as conservative estimates due to the nature of tephra capture and preservation in the sedimentary record

linking the north atlantic to central europe a high resolution holocene tephrochronological record from northern germany a high resolution holocene tephrochronology for northern germany has been established based on systematic tephrostratigraphical analysis of three peat bogs microscopic volcanic ash layers have been traced and characterised petrographically and by the chemical composition of the glass shards at least 37 ash horizons representing 16 different explosive volcanic eruptions have been identified and many can be correlated between the three sites up to 100 km apart the tephra layers can be related to icelandic volcanic sources and some correlated to the eruptions of askja 1875 hekla 3 hekla selsund hekla 4 and hekla 5 as well as to unspecified eruptions of icelandic volcanic systems e g torfajokull the source volcanoes for some tephra layers remain unidentified some tephra layers were known previously from the north atlantic region e g sluggan glen garry others have not been recorded previously in the literature e g microlite tephra this study provides the first comprehensive holocene tephrostratigraphical record for northern germany complementing the north atlantic tephrostratigraphical dating framework effectively extending it into central europe the study shows that icelandic ash layers are even more widespread than hitherto thought copyright 2002 john wiley sons ltd

tephra geochemistry a discussion of some persistent analytical problems distal tephrochronological studies are reliant upon precise and accurate geochemical quantitation this quantitation can involve difficulties not often encountered in more conventional petrology solving these problems is of particular importance in the holocene and late quaternary of northwest europe where numerous tephra layers of icelandic origin have been detected in peat bogs and lake and marine sediments electron probe microanalysis epma has proved the most applicable analytical technique when insufficient quantities of tephra are available for bulk analysis standard epma techniques require fine tuning to the tephra problem as the geochemical instability of glass is a common feature in many previous studies geochemical data of avoidably low quality have been produced and little attention appears to have been directed to modification of epma methods it is suggested that the black box approach to geochemical analysis should be avoided by the consideration of several factors these include

recent holocene paleo environmental evolution and coastline changes of kition larnaca cyprus mediterranean sea abstract sedimentological paleontological analysis and 14c dating of 17 cores obtained in the vicinity of the phoenician military harbor viii iv bc of kition bamboula cyprus provide new paleo environmental information for the reconstruction of shoreline changes for kition and larnaca bay over the last 4000 years we propose that a communication existed between the inner harbor of bamboula presently 400 m inland and the northern district of lichines which was a marine embayment our core data led us to revisit the previous hypothesis of a direct east west channel between the harbor and the open sea nicolaou k 1976 the historical topography of kition studies in mediterranean archaeology goteborg vol 153 pp 1 373 gifford j a 1978 paleogeography of archaelogical sites of the larnaca lowlands southeastern cyprus phd thesis university of minnesota pp 1 192 we propose instead that a spit of coarse material isolated the lagoon from the open sea from 2600 to 1600 years bp

new major element analyses of proximal tephras from the azores and suggested correlations with cryptotephras in north west europe the azores archipelago is one of the most active volcanic areas in the north atlantic region approximately 30 eruptions have been reported over the last 600 years with some major vei 5 volcanic e

atmospheric pb pollution by pre medieval mining detected in the sediments of the brackish karst lake an loch mor western ireland abstract this paper presents results of geochemical investigations of lake sediments from the karst lake an loch mor aran islands including the first highly resolved record of atmospheric roman pb pollution for ireland the natural pb influx into the lake is largely contributed by 3 pb components which differ in their isotopic composition detrital influx of pb from the siliciclastic input dissolved influx of pb released by weathering of the local limestone and dissolved influx of seawater pb the balance between the 3 pb components varies in concert with the hydrological evolution of the lake the influx of pb in dissolved form is estimated by geochemical mass balance assuming that the siliciclastic influx is characterised by the pb al ratio of the late glacial clastic sediments it typically accounts for 50 80 of total pb input in the holocene sediments of an loch mor the natural dissolved influxes of pb sc and y reach a similar order of magnitude normalisation with sc and y is applied to quantify contributions from anthropogenic pb based on continuous sampling of 1 cm sample slices variations in the influx of roman pb could be reconstructed at a time resolution of c 5 a combined geochemical and pb isotope mass balance is used to characterise the isotopic composition of anthropogenic pb distinctly enhanced influx of anthropogenic pb occurs in the 1st and 2nd century ad and shows high variability on decadal scale this is in contrast to central european pb records which document a gradual increase and decrease in ancient atmospheric pollution by roman pb the reconstructed high variability in the influx of roman pb in an loch mor documents variations in the wind regime of western europe temporarily favouring the transport of atmospheric pb to western ireland

micro tephra in the west runton freshwater bed preliminary results abstract a volcanic mineral assemblage is present throughout the 20 120 m size fraction of the middle pleistocene west runton freshwater bed norfolk uk glass shards are extremely rare but are present mainly at one horizon this micro tephra assemblage is indicative of a potassic mineral suite possibly from an evolved phonolitic or trachytic melt mineralogical and electron microprobe data are inconsistent with a tephra source from mid atlantic ridge sites and the amphibole and alkali feldspar components are more evolved than early quaternary mineral assemblages from west eifel volcanism in germany the mineral assemblage and geochemical compositions are most similar to those from the mont dore area massif central france and the italian volcanic complex of mount vulture in the southern apennines taken alone these preliminary data are not strong enough to infer a deposit age however the age ranges for volcanism at both mont dore and mount vulture are similar 500 800 ka the presence of micro tephra from either of these sources is wholly consistent with other age estimates for the west runton freshwater bed 500 ka and

explosive silicic volcanism in iceland and the jan mayen area during the last 6 ma sources and timing of major eruptions abstract fifty three major explosive eruptions on iceland and jan mayen island were identified in 0 6 ma old sediments of the north atlantic and arctic oceans by the age and the chemical composition of silicic tephra the depositional age of the tephra was estimated using the continuous record in sediment of paleomagnetic reversals for the last 6 ma and paleoclimatic proxies 18 o ice rafted debris for the last 1 ma major element and normative compositions of glasses were used to assign the sources of the tephra to the rift and off rift volcanic zones in iceland and to the jan mayen volcanic system the tholeiitic central volcanoes along the iceland rift zones were steadily active with the longest interruption in activity recorded between 4 and 4 9 ma they were the source of at least 26 eruptions of dominant rhyolitic magma composition including the late pleistocene explosive eruption of krafla volcano of the eastern rift zone at about 201 ka the central volcanoes along the off rift volcanic zones in iceland were the source of at least 19 eruptions of dominant alkali rhyolitic composition with three distinct episodes recorded at 4 6 5 3 3 5 3 6 and 0 1 8 ma the longest and last episode recorded 11 pleistocene major events including the two explosive eruptions of tindfjallajokull volcano thorsmork ca 54 5 ka and katla volcano solheimar ca 11 9 ka of the southeastern transgressive zone eight major explosive eruptions from the jan mayen volcanic system are recorded in terms of the distinctive grain size mineralogy and chemistry of the tephra the tephra contain k rich glasses k 2 o sio 2 0 06 ranging from trachytic to alkali rhyolitic composition their normative trends ab q or and their depleted concentrations of ba eu and heavy ree reflect fractional crystallisation of k feldspar biotite and hornblende in contrast their enrichment in highly incompatible and water mobile trace elements such as rb th nb and ta most likely reflect crustal contamination one late pleistocene tephra from jan mayen was recorded in the marine sequence its age estimated between 617 and 620 ka and its composition support a common source with the borga pumice formation at sor jan in the south of the island

multi proxy evidence for holocene lake level and salinity changes at an loch mor a coastal lake on the aran islands western ireland abstract curves for holocene lake levels and salinity changes are presented for an loch mor a small oligohaline lake on the aran islands off the west coast of ireland based on palaeoecological investigations of a 12 m long lake sediment core new insights are also provided into holocene sea level change in the galway bay region particular emphasis has been placed on the ostracod fauna both past and present salinity and lake level changes were reconstructed from the fossil ostracod assemblages based on the known tolerances of individual species and on the assemblages as a whole additional evidence was provided by other proxies including strontium isotope ratios derived from ostracod shells and other carbonates plant macrofossil and pollen analyses and sedimentological changes the early holocene pre boreal i e 11 5 10 ka was characterised by low lake levels and slightly elevated salinity values probably the result of high evapotranspiration and low precipitation rather than elevated sea levels early holocene plant and animal migration to the island does not seem to have been impeded but relative sea levels were not necessarily so low below 40 m a s l that landbridges were present to the mainland between ca 10 and 8 5 ka relatively high lake levels prevailed at 8 3 and 7 5 ka minor fluctuations lowering of the lake level occurred that are assumed to relate to early holocene abrupt events beginning at 7 05 ka lake levels declined sharply a general trend towards rising lake levels started at ca 6 4 ka and accelerated at ca 5 6 ka as runoff increased as a result of neolithic clearances at ca 4 8 ka lake levels began to rise once again probably in response to changes in rainfall and or evapotranspiration and runoff lower lake levels during the first half of the 1st millennium ad were probably a response to decreased runoff as a result of a drier climate coupled with regeneration of woody vegetation the sharpest rise in both lake levels and salinity began during the ninth century ad which is attributed to a rapid rise in relative sea level

volcanic aerosol records and tephrochronology of the summit greenland ice cores the recently collected greenland ice sheet project 2 gisp2 and greenland ice core project ice cores from summit greenland provide lengthy and highly resolved records of the deposition of both the aerosol h2so4 and silicate tephra components of past volcanism both types of data are very beneficial in developing the hemispheric to global chronology of explosive volcanism and evaluating the entire volcanism climate system the continuous time series of volcanic so42 for the last 110 000 years show a strong relationship between periods of increased volcanism and periods of climatic change the greatest number of volcanic so42 signals many of very high magnitude occur during and after the final stages of deglaciation 6000 17 000 years ago possibly reflecting the increased crustal stresses that occur with changing volumes of continental ice sheets and with the subsequent changes in the volume of water in ocean basins sea level change the increase in the number of volcanic so42 signals at 27 000 36 000 and 79 000 85 000 years ago may be related to initial ice sheet growth prior to the glacial maximum and prior to the beginning of the last period of glaciation respectively a comparison of the electrical conductivity of the gisp2 core with that of the volcanic so42 record for the holocene indicates that only about half of the larger volcanic signals are coincident in the two records other volcanic acids besides h2so4 and other so42 sources can complicate the comparisons although the threshold level picked to make such comparisons is especially critical tephra has been found in both cores with a composition similar to that originating from the vatnaoldur eruption that produced the settlement layer in iceland mid a d 870s from the icelandic eruption that produced the saksunarvatn ash 10 300 years ago and from the icelandic eruption s that produced the z2 ash zone in north atlantic marine cores 52 700 years ago the presence of these layers provides absolute time lines for correlation between the two cores and for correlation with proxy records from marine sediment cores and terrestrial deposits containing these same tephras the presence of both rhyolitic and basaltic shards in the z2 ash in thegisp2 core and the composition of the basaltic grains lend support to multiple icelandic sources torfajokull area and katla for the z2 layer deposition of the z2 layer occurs at the beginning of a stadial event further reflecting the possibility of a volcanic triggering by the effects of changing climatic conditions

establishing chronologies for woodland small hollow and mor humus deposits using tephrochronology and radiocarbon dating chronological precision is a pre requisite for all palaeoecological analyses especially in more recent holocene deposits such as small hollow peat and mor humus in woodlands here tephrochronology was employed to improve the chronological control of such deposits to aid subsequent sub fossil insect analyses from three sites in western and southwestern ireland six tephra layers were detected from the three small hollows but only one from the mor humus sites four of the layers were matched to known tephra horizons regularly recorded in ireland while two new tephras of possible azores and grimsvotn origin were recorded the latter tephra may be the first definitive record of laki 1783 4 from ireland and is potentially an important new chronological marker for irish palaeoecological investigations of late holocene deposits results suggest that tephrochronology is a successful additional chronological tool for small hollow palaeoecological studies but is less helpful in mor humus deposits

geoarchaeology of sidon s ancient harbours phoenicia abstract geoarchaeological data from sidon s ancient harbour areas elucidate six evolutionary phases since the bronze age 1 at the time of sidon s foundation during the third millennium bc medium sand facies show the city s northern and southern pocket beaches to have served as proto harbours for middle to late bronze age societies 2 towards the end of the late bronze age and the early iron age expanding international trade prompted coastal populations into modifying these natural anchorages in sidon s northern harbour transition from shelly to fine grained sands is the earliest granulometric manifestation of human coastal modification the lee of zire island was also exploited as a deep water anchorage or outer harbour at this time 3 although localised sediments evoke developed port infrastructure during the phoenician and persian periods high resolution reconstruction of the northern harbour s iron age history is problematic given repeated dredging practices during the roman and byzantine periods 4 fine grained silts and sands in the northern harbour are coeval with advanced roman engineering works significantly deforming the coastal landscape bio and lithostratigraphical data attest a leaky lagoon type environment indicative of a well protected port 5 the technological apogee of sidon s northern harbour is recorded during the late roman and byzantine periods translated stratigraphically by a plastic clays unit and brackish lagoon fauna 6 a final semi abandonment phase comprising coarse sand facies concurs silting up and a 100 150 m progradation of the port coastline after the seventh century ad we advance three hypotheses to explain these stratigraphic data namely cultural tectonic and tsunamogenic finally our results are compared and contrasted with research undertaken in sidon s sister harbour tyre

assessing the impact of icelandic volcanism on vegetation systems in the north of ireland in the fifth and sixth millennia bc the lairg tephras comprise two of the three most abundantly represented tephra layers in irish holocene peat sequences the impact of these tephras on the vegetation at two lowland raised bogs in northern ireland is investigated through high resolution pollen percentage and concentration studies the palynological response of mire and dryland taxa to the tephra falls is assessed no significant palynological response to either tephra event is recorded

a younger dryas ash bed in western norway and its possible correlations with tephra in cores from the norwegian sea and the north atlantic abstract a bed of volcanic ash up to 23 cm thick is found in lacustrine and marine sediments in western norway it is formally mamed the vedde ash bed and its age is approximately 10 600 yr b p i e mid younger dryas the bed consits of pure glass having a bimodal basaltic and rhyolitic somposition the geochemistry of the glass shards suggests an icelandic source by means of stratigraphic position and geochemistry the ash is correlated with ash zones found in cores from the continental shelf the norwegian sea and the north atlatic

recent volcanic history of the veidivotn fissure swarm southern iceland an approach to volcanic risk assessment abstract the recent volcanic history of the southwestern part of the veidivotn fissure swarm southern iceland provides a basis for assessment of volcanic risk in an area of large hydropower potential local tephrastratigraphy and regional tephrochronology provide relative and absolute dating of individual eruptions as well as information on the volume and distribution of the products formed in each eruption three large eruptions took place in this area in 1480 a d 900 a d and 150 a d respectively each eruption produced approx 1 km3 dre of basaltic and minor amounts of silicic lava and tephra on fissures up to 42 km long no evidence is found of smaller eruptions during this period the estimated eruption frequency one eruption every 600 800 years implies that this part of the veidivotn fissure swarm is inactive for long periods between relatively large volcanic events a change in the mode of eruption from effusive to explosive took place during this period the hazards posed by this area include far reaching lava flows widespread heavy tephra fall with thicknesses in excess of 2 m at distances of 10 km and damming of a large glacial river with the consequent formation of unstable lakes a volcano tectonic model which explains the observed eruption frequency and provides a basis for a long term monitoring program is proposed eruptions on the veidivotn fissure swarm are interpreted as corollaries of rifting episodes initiated in the bardarbunga central volcano volcano tectonic episodes affect the fissure swarm at an average interval of 100 years minor episodes are limited to the central volcano and adjacents parts of the fissure swarm during the less frequent major episodes rifting and volcanic activity extends to the extreme southwestern part of the fissure swarm seismic monitoring of the bardarbunga central volcano could provide an early warning of renewed activity on the veidivotn fissure swarm a major rifting episode resulting in eruption on its southwestern part can be expected during the next 100 to 300 years

tephrochronology of recent events in the andean range northern patagonia spatial distribution and provenance of lacustrine ash layers in the nahuel huapi national park tephrochronology is a powerful tool for dating sedimentary sequences especially in patagonia where a large number of active volcanoes have produced frequent historical eruptions short lacustrine sedimentary sequences were extracted from the lakes moreno oeste and ton cek nahuel huapi national park seventeen volcanic ash layers were identified in both cores 210 pb and 137 cs were used for dating techniques and historical volcanic records were employed for correlation white pumice and glass shards from the tephras were characterised by measuring major and trace element contents by instrumental neutron activation analysis two volcanic sources the cordon caulle and the calbuco volcanoes were recognised as the prevailing systems that impacted the area in the past 800 1000 a the calbuco volcano was mainly responsible for the nine tephras identified in the lake ton cek sequence four of these nine tephras also contained material from the cordon caulle complex and could be interpreted as composite tephras or possible reworked ones the calbuco volcano showed predominant influences in the lake moreno oeste sequence six of the eight tephras identified in such a sequence were from the calbuco volcano and three of these six contained material from the cordon caulle complex the other two were from the cordon caulle complex with contributions from the calbuco volcano in one of them these findings show that the high frequency of volcanic events in the study region demands an accurate characterisation of the products generated by each source as well as an evaluation of their spatial distribution to obtain a consistent framework for dating recent environmental changes copyright 2010 john wiley sons ltd supporting information can be found in the online version of this article

the eyjafjallajokull ad 2010 eruption and the preservation of medium sized eruptions in marine surface sediment offshore southern iceland the recent volcanic eruptions of eyjafjallajokull 2010 and grimsvotn 2011 demonstrated the risks that mediumsized explosive icelandic eruptions pose to the north atlantic region using the eyjafjallajokull 2010 eruption as a case study we assess how traceable such eruptions are in the marine sedimentary record at medial distances from the source and investigate which factors have affected the particle transport to the marine sedimentary archive during r v poseidon cruise 457 we recovered 13 box cores at 100 1600 m water depths and distances of 18 180 km southwest south and east of iceland volcanic glass shards from the uppermost surface sediment were analyzed for their major element composition by electron microprobe and assigned to their eruptive source by geochemical fingerprinting the predominantly basaltic particles are mostly derived from the katla grimsvotn lakagigar and bar arbunga vei ivotn volcanic systems we also identified rhyolitic particles from the askja 1875 and oraefajokull 1362 eruptions only three out of almost 900 analyzed glass shards are derived from the recent eyjafjallajokull 2010 eruption suggesting that medium sized eruptions are only poorly preserved in marine sediments located at medial distances southwest to east of iceland we conclude that the frequency of past medium sized eruptions is likely higher than detectable in this archive

defining the potential source region of volcanic ash in northwest europe during the mid to late holocene abstract far travelled volcanic ash fine grained tephra clouds pose economic and societal risks largely through their potential impact on the aviation industry a long view of ash clouds extending over northwest europe assembled from the study and geochemical characterisation of cryptotephra i e tephra invisible to the naked eye in sedimentary records can help inform the understanding of the frequency of such events and the nature of eruptions that generate them here we review the records of cryptotephra deposition in northwest europe during the mid to late holocene the last eight millennia to gain insights into the sources of volcanic ash reaching this region we consider almost 500 published and unpublished datasets for cryptotephras recorded in sedimentary sequences ranging from ireland to latvia and on the basis of their major element geochemical composition we identify 90 unique ash horizons and their likely provenance the majority 72 of the cryptotephras derive from icelandic eruptions but a large proportion 24 originates from other volcanic regions including alaska the cascades kamchatka mexico the azores and possibly the mediterranean although moderate magnitude eruptions in iceland may potentially disperse ash clouds over europe it appears that only large magnitude events in more distant regions have generally had this capacity and then only when suitable meteorological conditions prevailed nevertheless the cryptotephra records demonstrate that ash clouds from most volcanic regions capable of producing large explosive eruptions in the northern mid to high latitudes particularly those to the west of europe as well as in tropical north america have the potential to extend to northwest europe volcanic ash forecasts for this region need therefore to take into account possible risks posed not only by icelandic eruptions but also by any large magnitude eruptions in north america or the north pacific area

icelandic volcanic ash and the mid holocene scots pine pinus sylvestris pollen decline in northern scotland a volcanic ash layer in peat from northern scotland has been identified and coincides exactly with an abrupt decline in pinus sylvestris l scots pine pollen frequencies this provides an isochrone time equivalent marker horizon with which to investigate the timing of the holocene pine decline furthermore two possible causes of the southward shift of the range of pinus in scotland c 4000 bp are suggested a direct effect of acid pollution by chemicals produced by the eruption of hekla h 4 or a volcanically induced climatic perturbation these possibilities have wider implications for the influence of volcanism on postglacial environmental change

identification of the icelandic landnam tephra ad 871 2 in scottish fjordic sediment certain marginal marine environments such as the scottish fjord systems contain high resolution records of palaeoclimatic change in which decadal to centennial climatic events can be resolved this paper explores the possibilities of using tephrochronology to stratigraphically constrain the timing of such events in the loch sunart record md04 2831 on the nw coast of scotland uk one tephra horizon containing both silicic and basaltic shards is identified within late holocene sediment with geochemical analyses of the basaltic shards suggesting an origin in the veidivotn bar arbunga volcanic system radiocarbon age estimates and stratigraphic information suggests that the ad 871 landnam tephra is the most likely candidate the shards identified within this horizon appear hydrated and indicate the operation of post depositional weathering processes possibly influenced by the saline conditions of the fjord environment

tephrochronological studies in northern england tephrostratigraphic investigations of two upland blanket bogs in northern england show that micro scopic layers of tephra are present their geochemistry shows that they are identical to two icelandic tephra layers of known age found at sites in scotland and the north of ireland the work extends the regional tephro chronology of the mid holocene for the british isles

first discovery of holocene alaskan and icelandic tephra in polish peatlands despite the discovery of cryptotephra layers in over 100 peatlands across northern europe holocene cryptotephra layers have not previously been reported from polish peatlands here we present the first holocene tephra findings from two peatlands in northern poland at bagno kusowo peatland we identify the most easterly occurrence of the ad 860 b tephra recently correlated to the white river ash wrae derived from mount churchill alaska a shorter core from linje peatland contains tephra from the askja 1875 eruption extending the spatial distribution and regional importance of this icelandic tephra in eastern europe our research indicates the potential of cryptotephra layers to date and correlate the growing number of palaeoenvironmental studies being conducted on polish peatlands and contributes towards the development of a regional holocene tephrostratigraphy for poland

harbor areas at ancient troy sedimentology and geomorphology complement homer s iliad for at least two thousand years scholars have debated the location of troy and the events and geographic features described in homer s iliad geologic evidence is used to present a series of maps of the trojan plain that show the geomorphic changes over the past six millennia the geologic evidence correlates very well with the relevant homeric geography

an outline tephrochronology for the holocene of the north of ireland geochemically typed thin layers of icelandic holocene tephras form a tephrochronology for the north of ireland tephrochronology construction is based on geochemical linkage with dated historic icelandic eruptions and high precision multisample radiocarbon dating comparison with geochemically typed holocene layers at sites throughout scotland and northern england shows that some layers are widespread throughout much of the northern british isles other layers of known historic date have so far been detected only in ireland

the tephrochronology of iceland and the north atlantic region during the middle and late quaternary a review the tephrochronology of iceland and the north atlantic region is reviewed in order to construct a unified framework for the last 400 kyr bp nearly all of the tephra layers described are also characterised geochemically a number of new tephra layers are analysed for the first time for their geochemical signature and a number of pre holocene tephra layers have been given an informal denotation the tephrostratigraphy of ash zone ii is highlighted where possible the rhyolitic tephra layers found outside iceland have been correlated to known icelandic tephra layers or to the volcanic source area the application of tephra fallout in various depositional environments is described and discussed copyright 2000 john wiley sons ltd

holocene explosive volcanism of the jan mayen island volcanic province north atlantic abstract the volcanic island jan mayen located in the norwegian greenland sea hosts the active stratovolcano of beerenberg the northernmost active subaerial volcano in the world at least five eruptions are known from the island following its discovery in the 17th century but its eruptive history prior to this is basically unknown in this paper two sediment cores retrieved close to jan mayen have been studied in detail to shed light on the holocene history of explosive volcanism from the jan mayen volcanic province horizons with elevated tephra concentrations were identified and tephra from these was analysed to determine major element chemistry of the tephra the tephra chemistry was used to provide a link between the two cores and the land based tephra records from jan mayen island we managed to link two well developed tephra peaks in the cores by their geochemical composition and age to jan mayen one of these peaks represents the 1732 ad eruption of eggoya while the other peak represents a previously undescribed eruption dated to around 10 3 ka bp two less prominent tephra peaks one in each core dated to approximately 2 3 and 3 0 ka bp also have a distinct geochemical character linking them to jan mayen volcanism however the most prominent tephra layer in the cores located close to jan mayen and numerous other cores along the jan mayen ridge is the 12 1 ka bp vedde ash originating from the iceland volcanic province we find that the holocene volcanism on jan mayen is much less explosive than volcanism in iceland and propose that either low amounts of explosive volcanic activity from the summit region of beerenberg or small to absent glacier cover on beerenberg is responsible for this

cryptotephra as a dating and correlation tool in archaeology a new development in archaeological chronology involves the use of far travelled volcanic ash which may form discrete but invisible layers within a site s stratigraphy known as cryptotephra these horizons can provide isochrons for the precise correlation of archaeological records at single moments in time removing or at least significantly reducing temporal uncertainty within inter site comparisons when a tephra can be dated elsewhere its age can be imported between records providing an independent check on other dating methods in use and valuable age estimates for difficult to date sequences the use of cryptotephra layers to date and correlate palaeoenvironmental archives is well established and there exists a wealth of tephra compositional data and regional tephrostratigraphic frameworks from which archaeological cryptotephra studies can benefit greatly existing approaches to finding and analysing cryptotephra are easily adapted to archaeological sequences so long as the often complex nature of archaeological stratigraphies and sediment taphonomy are borne in mind

using cryptotephras to extend regional tephrochronologies an example from southeast alaska and implications for hazard assessment abstract cryptotephrochronology the use of hidden diminutive volcanic ash layers to date sediments has rarely been applied outside western europe but has the potential to improve the tephrochronology of other regions of the world here we present the first comprehensive cryptotephra study in alaska cores were extracted from five peatland sites with cryptotephras located by ashing and microscopy and their glass geochemistry examined using electron probe microanalysis glass geochemical data from nine tephras were compared between sites and with data from previous alaskan tephra studies one tephra present in all the cores is believed to represent a previously unidentified eruption of mt churchill and is named here as the lena tephra a mid holocene tephra in one site is very similar to aniakchak tephra and most likely represents a previously unidentified aniakchak eruption ca 5300 5030 cal yr bp other tephras are from the late holocene white river eruption a mid holocene mt churchill eruption and possibly eruptions of redoubt and augustine volcanoes these results show the potential of cryptotephras to expand the geographic limits of tephrochronology and demonstrate that mt churchill has been more active in the holocene than previously appreciated this finding may necessitate reassessment of volcanic hazards in the region

late quaternary icelandic tephras in ireland and great britain detection characterization and usefulness microscopic studies of late quaternary tephras from iceland yield a detailed tephrochronology in deposits of the british isles where the quantities of volcanic glass employed are much less than those used to construct almost any other late quatemary tephrochronology we summarize improved methods of isolating extremely sparse glass shards for light microscope and electron microprobe analysis and provide major element geochemistry for 20 volcanic glass layers detected in ireland including those which comprise an outline historic tephrochronology for ireland the paper highlights possible limitations of chronology construction when attempting to separate dated tephras whose major element geochemistries are almost identical tephras in other parts of the british isles and europe are used with those in ireland to demonstrate further applications of tephrochronology especially for dating deposits where other dating methods e g radiocarbon have proved difficult

geochemical stability of fine grained silicic holocene tephra in iceland and scotland this paper tests two assumptions fundamental to the use of fine grained silicic tephras from iceland for creating chronological frameworks in northwest europe it is shown firstly that glass shards can retain their overall chemical integrity on at least a four millennial time scale in contrasting depositional environments in iceland and scotland and secondly that an acid digestion process the most practical method for extracting tephra from peat does not significantly bias the results of major element analysis by electron microprobe the implication is that there is great potential and an appropriate method for developing both the resolution and the spatial coverage of chronologies based on silicic icelandic tephras in northwest europe

the late quaternary tephrostratigraphy of annually laminated sediments from meerfelder maar germany abstract the record of late quaternary environmental change within the sediments of meerfelder maar in the eifel region of germany is renowned for its high precision chronology which is annually laminated throughout the last glacial to interglacial transition lgit and most of the holocene two visible tephra layers are prominent within the floating varve chronology of meerfelder maar an early holocene tephra layer the ulmener maar tephra 11 000 varve years bp provides a tie line of the meerfelder maar record to the varved holocene record of nearby lake holzmaar the laacher see tephra provides another prominent time marker for the late allerod 200 varve years before the transition into the younger dryas at 12 680 varve years bp further investigation has now shown that there are also 15 cryptotephra layers within the meerfelder maar lgit holocene stratigraphy and these layers hold the potential to make direct comparisons between the meerfelder maar record and other palaeoenvironmental archives from across europe and the north atlantic most notable is the presence of the vedde ash the most widespread icelandic eruption known from the late quaternary which occurred midway through the younger dryas the vedde ash has also been found in the greenland ice cores and can be used as an isochron around which the gicc05 and meerfelder maar annual chronologies can be compared near the base of the annual laminations in meerfelder maar a cryptotephra is found that correlates to the neapolitan yellow tuff erupted from campi flegrei in southern italy 1200 km away this is the furthest north that the neapolitan yellow tuff has been found highlighting its importance in the construction of a european wide tephrostratigraphic framework the co location of cryptotephra layers from italian icelandic and eifel volcanic sources within such a precise chronological record makes meerfelder maar one of the most important tephrostratotype records for continental europe during the last glacial to interglacial transition