sr and nd isotopes as tracers of north atlantic lithic particles paleoclimatic implications sr and nd isotopic compositions have been measured on the lithic fraction of last climatic cycle sediments from the north atlantic 40 n 60 n in order to identify the origins of the particles from the reconstruction of their transport pathways we deduce the mechanisms that explain their distributions the main source regions are the canadian shield mostly the area of baffin bay and western greenland the scandinavian shield the european region british isles and bay of biscay and iceland we observe a significant glacial interglacial contrast characterized by a dominant icelandic input via near bottom transport by north atlantic deep water nadw during the interglacials and a largely continent derived contribution of surface transported ice rafted detritus ird during the glacial period during the last glacial period the heinrich events abrupt massive discharges of ird originated not only from the laurentide ice sheet as heretofore envisioned but also from other sources three other major north atlantic ice sheets fennoscandian british isles and icelandic probably surged simultaneously discharging ice and ird into the north atlantic as opposed to theories implying a unique laurentide origin gwiazda et al 1995 driven by an internal mechanism mcayeal 1993 we confirm that the icelandic and the fennoscandian ice sheets also surged as recently proposed by other authors and we here also distinguish a possible detrital contribution from the british isles ice sheet this pan north atlantic phenomenon thus requires a common regional external forcing

smnd isotopic and geochemical characterisation of the paleoproterozoic torngat orogen labrador canada abstract the torngat orogen is a paleoproterozoic granulite facies belt that welds the archean components of the nain and rae provinces in eastern labrador sm nd isotopic and supporting bulk rock major trace and rare earth element data help elucidate the sources of the main paleoproterozoic lithologies that comprise the orogen in the foreland paleoproterozoic ramah group metasediments intercalated with reworked nain province gneiss show variable trace element and nd 1 9 ga from 2 9 to 12 0 ranging between nain province crust and paleoproterozoic mugford group basalts compositions the ramah group data suggest derivation of ramah detritus from archean nain province gneisses and from the mugford group in the lac lomier complex rae province hinterland metasediments with variable trace element distribution patterns akin to rae province crust and nd 1 9 ga from 2 9 to 10 5 suggest derivation from rae province crust and from an unspecified juvenile component in the core of the orogen pelitic and psammitic protoliths of the tasiuyak gneiss nd 1 9 ga from 1 9 to 2 6 were derived from crustal sources unknown in both nain and rae provinces and may have been deposited in a trench environment starved of adjacent cratonic debris dioritic to granitic eastern and western metaplutonic suites intruding the tasiuyak gneiss and the lac lomier complex display contrasting geochemical and sm nd isotopic compositions the eastern metaplutonic suite has a tendency toward lower sio2 total alkalis less fractionated ree and higher mgo cao and tio2 relative to the western metaplutonic suite the eastern suite yields nd 1 9 ga from 3 8 to 6 7 and negative f sm nd suggesting igneous precursors from rae crust and a a lree enriched juvenile component the western suite yields nd 1 9 ga from 1 5 to 8 5 suggesting an important contribution from rae crustal sources in the petrogenesis of the igneous protoliths the presence of rae province nd isotopic compositions and the absence of nain province signatures in these intrusions favors the eastern rae province as the active margin during nain rae convergence

processes of initiation of motion leading to bedload transport in gravel bed rivers 1 transport processes that lead to the initiation of bedload motion in gravel bed rivers have not yet been clarified we report patch and grain scale processes involved in the initiation of bedload motion in a natural gravel bed stream as observed through a series of video experiments with increasing flow strength the phases of initiation of motion that have been identified are 1 within patch grain instability grain vibration pivoting and grain scale rolling 2 within patch gyratory step and rest motion and 3 general sediment motion involving downstream transport from an individual patch and the throughput of grains inherited from upstream

origin of the northern atlantic s heinrich events as first noted by heinrich 1988 glacial age sediments in the eastern part of the northern atlantic contain layers with unusually high ratios of ice rafted lithic fragments to foraminifera shells he estimated that these layers are spaced at intervals of roughly 10 000 years in this paper we present detailed information documenting the existence of the upper five of these layers in odp core 609 from 50 n and 24 w their ages are respectively 15 000 radiocarbon years 20 000 radiocarbon years 27 000 radiocarbon years about 40 000 years and about 50 000 years we also note that the high lithic fragment to foram ratio is the result of a near absence of shells in these layers although we are not of one mind regarding the origin of these layers we lean toward an explanation that the heinrich layers are debris released during the melting of massive influxes of icebergs into the northern atlantic these sudden inputs may be the result of surges along the eastern margin of the laurentide ice sheet

boulders of mis 5 age deposited by a tsunami on the coast of otago new zealand abstract a series of elevated imbricated boulders were investigated on the otago coastline southeast new zealand through field surveying and optical luminescence dating by using established hydrodynamic relationships of sediment transport the energy required to move the clasts was calculated and compared to the historic record of marine inundations of that coast the boulders are platy in shape and are over 2 m long in some cases and are sourced from a locally outcropping conglomerate unit which appears to be the only lithology on this section of coast that erodes to produce clasts of this size it is estimated that the boulders were deposited by a tsunami between 2 and 3 m high during the latter part of marine isotope stage 5 they therefore represent the first pre holocene tsunami deposit and one composed of large boulders described on the new zealand coastline

rare earth elements and nd and pb isotopes as source indicators for labrador sea clay size sediments during heinrich event 2 elemental abundances and nd and pb isotope ratios were determined on samples from the carbonate free clay size fractions of sediments from intervals above within and below heinrich event 2 h 2 in core hu87 9 from the northwest labrador sea slope in hu87 9 rare earth element ree distributions and elemental concentrations within the h 2 event are distinct from those outside this event end 0 and 206 pb 204 pbdata also indicate different values for sediments deposited within and outside the h 2 event comparisons of ree patterns from the h 2 interval with those from bedrock units in baffin island northern quebec and labrador indicate that the lake harbour group lhg which crops out on the north side of the hudson strait is the most probable bedrock source of the clay size fraction found within the h 2 interval in hu87 9 the tasiuyak gneiss tg and lac lomier complex llc have ree patterns including a negative eu anomaly similar to those found in h 2 sediments however the la ybratios of these units are smaller than those associated with h 2 sediments the nd and pbisotope data support and complement ree based interpretations of provenance i e the nd pb signatures of sediments deposited at the hu87 9 site during the h 2 event are similar to nd pbsignatures ob tained on diamicts from the western end of hudson strait published by elsevier science ltd

clay mineral signature of the nw atlantic boundary undercurrent abstract surface sediments were sampled along 2 transects across the iceland and irminger basins and in the labrador sea clay mineral assemblages deduced from x ray analyses of the carbonate free

a continuum mixture model of ice stream thermomechanics in the laurentide ice sheet 1 theory we employ a continuum mixture framework to incorporate ice streams in a three dimensional thermomechanical model of the laurentide ice sheet the ice mass is composed of a binary mixture of sheet ice which deforms by viscous creep and stream ice which flows by sliding and or sediment deformation at the bed dynamic and thermal evolutions are solved for each component in the mixture with coupling rules to govern transfer between flow regimes we describe two different transfer mechanisms 1 creep exchange the nourishment of ice streams by viscous creep inflow from the surrounding ice sheet and 2 bed exchange the activation growth and deactivation of ice streams perpetrated by transfers of bed area between flow constituents this paper develops the underlying mixture theory we express the governing equations for mass momentum and energy balance in a form suitable for direct incorporation in existing numerical models of ice thermomechanics a companion paper in this issue explores mixture and ice stream behavior in applications with the laurentide ice sheet

signatures of natural catastrophic events and anthropogenic impact in an estuarine environment new zealand the sedimentary record of known natural catastrophic events and anthropogenic activity in an estuarine environment is assessed using sedimentological chemical and geochronological techniques shallow cores collected from intertidal and salt marsh sediments in ahuriri estuary hawke s bay reveal a variety of signatures of natural and human disturbance evidence for the 1931 hawke s bay earthquake which resulted in an uplift of one to two metres in the napier area is given by a change from silt to sand dominated sediment in the lower estuary which is consistent with a shift toward higher energy depositional conditions following uplift however based on physical properties of sediments the 1931 uplift event does not appear to have caused major changes in depositional conditions in the upper estuary similarly no changes were recorded at one site in the lower estuary which seems to represent an area of low energy depositional environment although the 1960 chilean tsunami resulted in structural damage in napier it did not produce any recognisable sedimentological and geochemical signature in the sedimentary record suggesting that the study sites were possibly beyond the limit of sedimentation of the tsunami post european settlement impact is mainly restricted to the lower estuary where increased concentrations of zn cr pb and cu are attributed to industrial discharges evidence of agricultural runoff is shown by an increase in cu concentrations within a fine grained depositional environment that is distal from industrial sources in the town of napier chemical data cl and s suggest a change in the depositional environment in the upper estuary due to increased freshwater influx and or decrease in seawater influence dating by 210pb suggests that this occurred around the middle part of the 19th century and might be attributed to river flooding in the region at that time

origin and consequences of cyclic ice rafting in the northeast atlantic ocean during the past 130 000 years deep sea sediment cores recovered from the northeast atlantic ocean were examined in order to elucidate the influence of the earth s orbital parameters on major ice rafting analyses of coarse grained ice rafted debris and planktonic foraminifers revealed a strong reaction to the precession signal since 130 000 yr b p dropstone layers have been deposited each half period of a precessional cycle 11 000 1000 yr ice rafting occurs during times of winter minimum summer maximum insolation and summer minimum winter maximum insolation in the first case high summer insolation forces meltwater discharge from the ice sheets into the polar seas which subsequently enhances formation of sea ice during the winter in the second case growth of continental ice enhances iceberg production which also leads to a salinity reduction of surface seawater both situations result in a southward penetration of polar water thus the marine record of dropstones documents ice rafting not only during weichselian stades but also during cold events within interstades the regularity of ice rafting yields a useful framework to calibrate and elucidate climatic changes not only in the region of the north atlantic ocean but also in remote areas such as the pacific ocean and the antarctic

evidence of tsunami sedimentation on the southeastern coast of australia in coastal regions the highest magnitude storms cannot always be invoked to account for large scale anomalous sediment features any coastline in the pacific ocean region can be affected by tsunamis including australia which historically lacks evidence of such events geologically tsunamis along the new south wales coast have deposited a suite of holocene features that consist of anomalous boulder masses either chaotically tossed onto rock platforms and backshores or jammed into crevices highly bimodal mixtures of sand and boulders and dump deposits consisting of well sorted coarse debris in addition many coastal aboriginal middens were distributed by such events within estuaries tsunamis have left a record of stranded run up ridges that have been interpreted mistakenly as cheniers dating of such deposits indicates that several events have affected this coastline since 3000 bp in contrast to storm waves tsunamis can leave a depositional imprint of their passage characterized by chaotic sort

theoretical constraints and chronological evidence of holocene coastal development in central and southern new south wales australia abstract holocene coastal evolution in new south wales has been interpreted essentially as the unfolding of the impact of marine transgression sea level on this coast supposedly reached its present height at 6 6 5 ka and varied

diatom biostratigraphy of tsunami deposits examples from the 1998 papua new guinea tsunami abstract distinctive diatom assemblages may be associated with tsunami sediments and may often contrast with the assemblages found within sediments underlying the tsunami deposit as well as those associated with the modern coastal environment sediments associated with the 1998 tsunami that destroyed much of the sissano lagoon area in northern papua new guinea have been investigated surface sediments from three transects across the sediment spit near warapu have been examined for diatom content and preservation the preservation is variable and the data show an often chaotic assemblage that can be attributed to the tsunami waves incorporating and depositing diatoms from distinctive habitat zones during their runup and subsequent backwash the diatoms identified within the warapu sediments indicate an origin from within the inter tidal and offshore area rather than from the beach sand spit complex the sand deposits disclose a high percentage in excess of 75 of broken diatom valves and a predominance of centric circular species due to preferential preservation the study demonstrates that the application of diatom biostratigraphy to modern tsunami deposits can be used in conjunction with other stratigraphical lines of evidence to interpret the source and provenance of historical and palaeo tsunami deposits

holocene sea level change on the southeast coast of australia a review a revised holocene sea level curve for the southeast coast of new south wales australia is presented based on a review of previously published geochronological results for fossil molluscs organi

changes in the western boundary undercurrent outflow since the last glacial maximum from smectite illite ratios in deep labrador sea sediments high resolution mineralogical studies were performed on late glacial and deglacial sediments from two deep piston cores from the labrador sea located at the inlet sw greenland rise and outlet labrador rise of the western boundary undercurrent wbuc gyre at the two sites smectites transported from the eastern iceland and irminger basins by the wbuc are observed clay mineral changes are used as proxies for the paleointensity reconstruction of the wbuc on the greenland rise a clay mineral index smectite illite s i ratio is defined a s i ratio of 1 characterized the last glacial maximum it increased after 17 ka and reached a maximum value of 4 during the early holocene the mineralogical changes are gradual and do not show any reversal during the younger dryas this pattern which is confirmed by first order estimations of smectite and illite fluxes suggests gradually increasing sedimentary fluxes and wbuc intensity since the last glacial maximum a peak in the velocity of the wbuc at 9 ka as recorded by clay assemblages is consistent with other regional studies based on pollen foraminifera or grain size measurements a massive dilution of smectites by illite and chlorite s i 3 occurs at 8 5 ka it corresponds to a period of rapid sediment accumulation and reflects an intensified illite rich detrital supply by meltwaters from the southern greenland ice margin on the labrador rise the smectite content varies between 20 and 60 with no obvious trend through time the mineralogical composition is strongly influenced by ice rafted deposition and by the abundance of fast deposit units cf heinrich layers in the north atlantic which contain abundant detrital carbonates spilled over from the north west atlantic mid ocean channel in such layers smectites are present but are diluted by the addition of illites chlorites and kaolinites this provides evidence for a discrete and continuous wbuc supply of fine particles from the irminger and iceland basins as far as the southeastern part of the labrador basin early deglacial smectite rich layers up to 60 are also observed at this site they indicate an increase in the outflow of the wbuc at 13 5 ka bolling allerod as previously reported from grain size or foraminiferal assemblage studies

the distribution of apparent dose as determined by optically stimulated luminescence in small aliquots of fluvial quartz implications for dating young sediments abstract we noted recently murray et al 1995 that quartz samples taken from in channel fluvial deposits have apparent doses ranging over several orders of magnitude we suggested that these dose distributions are best explained by a mixture of a small number of poorly bleached grains and a larger number of well bleached grains in this paper we examine the distribution of apparent dose in small aliquots each composed of 2000 grains of different particle size fractions 63 90 m 90 125 m 125 180 m 180 212 m 212 250 m diameter from two samples collected from the murrumbidgee river new south wales australia the samples are of known burial age the first being 70 years old and the second being its modern equivalent 0 2 gy the difference in the lowest apparent dose in the two samples is considered to be the result of their different burial times we suggest a method for dating recently deposited

ice rafted debris associated with binge purge oscillations of the laurentide ice sheet the north atlantic sediment record suggests quasi periodic 7000 to 12 000 year period ice rafted debris ird depositions during at least the last glacial period the cause of these heinrich events as they are commonly known is not fully understood however they may point to surges of the ice stream that drained the hudson bay hudson strait region of the laurentide ice sheet we investigate a simple conceptual model of ice stream instability the binge purge model to suggest ways in which the ice stream could have entrained sufficient debris to account for the estimated mass of ird associated with a typical heinrich ird layer in the north atlantic 1 0 0 3 1015 kg we find that freezing of debris laden ice at the bed of the ice stream during the brief 750 years surge phase of the ice stream s hypothesized binge purge cycle can incorporate up to 5 1 1015 kg this amount is sufficient to meet the constraints of the north atlantic sediment record but by no means verifies the binge purge model as the cause of heinrich events

biomarker determination as a provenance tool for detrital carbonate events heinrich events fingerprinting quaternary glacial sources into baffin bay sedimentary deposits associated with heinrich events are anomalously rich in detrital carbonate off hudson strait the dominant carbonate is calcite whereas at distal sites in the north atlantic dolomite is dominant more diagnostic a significant source for dolomite is its outcrop at the northern end of baffin bay where major ice streams from the laurentide innuitian and greenland ice sheets converged the provenance of samples containing detrital carbonate mainly dolomite from a core in baffin bay has been confirmed using organic geochemistry to distinguish between alternative sources based upon the thermal maturity of organic matter in carbonates of the source region the core contained five distinct carbonate units dating between 14 and 51 cal ka bp and indicates significant ice stream instability associated with iceberg calving and significant volumes of meltwater the exact temporal relationship to heinrich events is not yet clear a long mid wisconsin interval 38 to 22 cal ka bp devoid of detrital carbonate suggests a major reduction in ice extent at high northern latitudes the core samples yield thermally sensitive biomarker ratios comparable to those from laurentian carbonates in the canadian arctic islands but unlike those from north greenland identifying the former region as their provenance however a late holocene sample from off newfoundland shows a stronger affinity with greenland 2007 elsevier b v all rights reserved

evidence from sites in western ireland of late holocene changes in coastal environments the presence of sand layers interleaved with biogenic material in coastal sedimentary sequences from back barrier areas has often been used as evidence of storm surge or tsunami action during the holocene this paper discusses such stratigraphies from two adjacent sites in western ireland in order to assess the validity of this inference detailed examination of the sand layers indicates that while some of the sand beds at one of the sites were deposited by overwash other processes including aeolian deposition and fluvial reworking of aeolian sediments were also important in sand redistribution in the back barrier areas in these cases local controls including site drainage characteristics barrier morphology and available sediment supply appear to have been important in site evolution a regional signal of storm frequency was not detected

warmer or cooler late holocene marine palaeoenvironments interpreting southeast australian and brazilian sea level changes using fixed biological indicators and their δ18o composition abstract relic inter tidal assemblages of sessile organisms which are referred to as fixed biological indicators fbis are shown to be useful proxies for late holocene climatic and environmental changes as well as direct indicators of short term fluctuations in sea level a detailed comparison of change in the inter tidal assemblages of two southern hemisphere sites at comparable latitudes port hacking new south wales south east australia and the laguna imbituba region of southern brazil indicates periods of marked similarities in the timing and nature of changes at 5200 3800 cal years bp and differences after 2400 cal years bp there is sufficient concurrence of cooling phases and falling sea levels to strongly suggest that in some cases global rather than regional forcing factors are at work the value of inter tidal organisms as indicators of changed environments is developed by identifying the past and present distributions of the common marker species tubeworms barnacles and mussels the 18 o content of these extant specimens at port hacking confirmed changes in ocean water temperature and associated sea level behaviour corresponding to invasion or extinction of temperature sensitive species a similar pattern is repeated although in a less marked fashion in the laguna imbituba region of southern brazil

tsunami sedimentary facies deposited by the storegga tsunami in shallow marine basins and coastal lakes western norway sedimentary successions in small coastal lakes situated from 0 to 11 m above the 7000 year bp shoreline along the western coast of norway contain a distinctive deposit very different from the sediments above and below the deposit is interpreted to be the result of a tsunami inundating the coastal lakes an erosional unconformity underlies the tsunami facies and is traced throughout the basins with most erosion found at the seaward portion of the lakes the lowermost tsunami facies is a graded or massive sand that locally contains marine fossils the sand thins and decreases in grain size in a landward direction above follows coarse organic detritus with rip up clasts here termed organic conglomerate and finer organic detritus the tsunami unit generally fines and thins upwards the higher basins 6 11 m above the 7000 year shoreline show one sand bed whereas basins closer to the sea level 7000 years ago may show several sand beds separated by organic detritus these alternations in the lower basins may reflect repeated waves of sea water entering the lakes in basins that were some few metres below sea level at 7000 years bp the tsunami deposit is more minerogenic and commonly present as graded sand beds but also in some of these shallow marine basins organic rich facies occur between the sand beds the total thickness of the tsunami deposit is 20 100 cm in most studied sites an erosional and depositional model of the tsunami facies is developed

patterns of ice rafted detritus in the glacial north atlantic 40 55 n the observation by heinrich 1988 that during the last glacial period much of the input of ice rafted detritus to the north atlantic sediments may have occurred as a succession of catastrophic events rekindled interest on the history of the northern ice sheets over the last glacial period in this paper we present a rapid method to study the distribution of these events both in space and time using whole core low field magnetic susceptibility we report on approximately 20 cores covering the last 150 to 250 kyr well defined patterns of ice rafted detritus appear during periods of large continental ice sheet extent although these are not always associated within their maxima most of the events may be traced across the north atlantic ocean for the six most recent heinrich layers hl two distinct patterns exist hl1 hl2 hl4 hl5 are distributed along the northern boundary of the glacial polar front over most of the north atlantic between 40 and 50 n hl3 is more restricted to the central and eastern part of the northern atlantic the nd sr isotopic composition of the material constituting different heinrich events indicates the different provenance of the two patterns hl3 has a typical scandinavia arctic icelandic young crust signature and the others have a large component of northern quebec and northern west greenland old crust material these isotopic results obtained on core su 9008 from the north american basin are in agreement with the study by jantschik and huon 1992 who used k ar dating of silt and clay size fractions of an eastern basin core me 68 89 these data confirm the large spatial scale of these events and the enormous amount of ice rafted detritus they represent

inter tidal fixed indicators of former holocene sea levels in australia a summary of sites and a review of methods and models abstract the reconstruction of mid to late holocene marine environments using the calcareous remains of inter tidal fixed biological indicators as sea level proxies is reviewed useful palaeo environmental information can be obtained from the fossil evidence of successive invasions and disappearances of tropical and temperate species within the sub fossil inter tidal biological sequences examples illustrating spatially synchronous late holocene sea level fluctuations are described from 3000 km of north south coastline along eastern australia the method uses tightly constrained species such as the tubeworm galeolaria caespitosa which allows for the precise measurement of relative sea level fluctuations by using the differential between emerged sub fossil encrustations and current distributions of the same species the error range can be defined according to the extent of preservation of the relic distributions particularly the extent that diagnostic boundaries between species limited to different inter tidal zones have been preserved the rapidity of sea level fluctuations is inferred by the preservation from erosion of emerged shell layers as well as discontinuities in the relic biological sequences and the relative preservation of fragile species this apparent rapidity of sea level fluctuations as well as evidence of near uniform synchronous sea level heights along the north south span of the entire australian coast and equally consistent variations australia wide in spencer gulf and rottnest island raises questions about the predicted poleward decline of sea level curves derived from hydro isostatic rebound modelling

multiple implications of rare earth elements for holocene environmental changes in nam co tibet abstract rare earth elements rees from a 332 cm long core surface sediments and soils of the lake shores were examined with the aim of evaluating their suitability as a paleo environmental proxy rees were transported into the nam co lake not only by runoff but also by wind concentrations of ree in the core range from 97 57 to 162 98 ppm with an average of 126 5 ppm from 171 3 to 475 7 ppm in the soils of shores and from 65 03 to 354 03 ppm in the surface sediments with an average of 130 64 ppm the ree average of soils is 158 9 ppm for the northern shore 214 72 ppm for the southern shore 244 ppm for the eastern shore and 289 69 ppm for the western shore the ree average of surface sediments is 114 45 ppm for the northern lake 115 73 ppm for the eastern lake 129 69 ppm for the western lake 144 38 ppm for the southern lake and 150 95 ppm in the center of the lake suggesting an accumulation of rees in the center of the lake the ratios of lree hree range from 8 to 11 85 for the core from 7 8 to 11 8 for the surface sediments and from 6 5 to 14 5 for the soils which suggesting that lree are richer than hree the ree distribution patterns of all samples are characterized by v shape curves with slightly negative ce anomalies from 0 83 to 0 99 and obviously negative eu anomalies from 0 28 to 0 72 mn played an active role on the ce anomaly the values of ce showed almost no variance suggesting a stable post depositional environment in the core the rees peaks of 140 ppm occurred at 6 9 ka 307 cm 5 9 5 5 ka 292 287 cm 2 2 2 0 ka 262 252 cm and 1 78 ka 212 cm corresponding to the beginning of environmental shifts and or events while the rees peak at 0 91 0 87 ka 107 102 cm and the rees valley of

inflow and outflow facies from the 1993 tsunami in southwest hokkaido abstract we describe in detail the sedimentary facies provenance and grain size distributions of the 1993 tsunami deposits in the lower reaches of usubetsu river only two lithofacies were recognized a gravel lobe facies glf and a sand sheet facies ssf the gravel lobe facies was deposited rapidly by a hydraulic jump in contrast the sand sheet facies which contains both current ripples and dunes was deposited by a traction current under subcritical flow conditions we identified four stratigraphic units unit 1 unit 2 unit 3 and unit 4 in ascending order we interpreted units 1 and 2 as having been deposited by the inflow and outflow events of the first run up and units 3 and 4 by the inflow and outflow events of the second run up respectively units 3 and 4 were more widely distributed and coarser grained than units 1 and 2 because the second run up was larger than the first run up furthermore unit 4 was more widely distributed than unit 3 because the outflow eroded the inflow deposits grain size distributions of the inflow and outflow deposits were clearly different unit 4 deposits had a peak at 2 5 phi p 1 population in contrast unit 3 deposits had a bimodal distribution with peaks at 0 5 1 5 phi p 2 population and at 2 5 phi p 1 population a comparison of the tsunami deposits with other sedimentary deposits near the study area showed that the tsunami deposits were mainly derived from the seabed at depths below 5 5 m in the offshore area where the marine sands are about 2 2 5 phi in size and thus are the source of the p 1 population the p 2 population is derived from coarse 0 5 2 phi fluvial materials eroded during the tsunami run up according to our calculations benthic foraminiferal tests were entrained from the comparatively deep seabed at depths up to 100 m during the tsunami run up and included in the tsunami deposits

evidence for three north sea tsunamis at the shetland islands between 8000 and 1500 years ago abstract coastal fen and lake deposits enclose sand layers that record at least three holocene tsunamis at the shetland islands the oldest is the well known storegga tsunami ca 8100 cal yr bp which at the shetlands invaded coastal lakes and ran up peaty hillsides where it deposited sand layers up to 9 2 m above present high tide level because sea level at ca 8100 cal yr bp was at least 10 15 m below present day sea level the runup exceeded 20 m in two lakes we also found deposits from a younger tsunami dated to ca 5500 cal yr bp the sediment facies are similar to those of the storegga tsunami rip up clasts sand layers re deposited material and marine diatoms runup was probably more than 10 m yet another sand layer in peat outcrops dates to ca 1500 cal yr bp this sand layer thins and fines inland and was found at two sites 40 km apart and traced to ca 5 6 m above present high tide the oldest tsunami was generated by the storegga slide on the norwegian continental slope we do not know what triggered the two younger events

late holocene higher sea level indicators from eastern australia abstract new age data from intertidal organisms exposed on coastal cliffs in northern new south wales suggest that in that area sea level was slightly more than 1 m higher about 3420 yrs b p and may have fallen to its present level since 1780 yrs b p these findings if regionally significant are important because they indicate that the tidally constructed zonations of organisms on high energy rocky coast could provide a more precise record of sea level behaviour than the study of constructional geomorphic features often related to storm events such as beach ridges chenier plains tidal deltas etc or mangrove peats

letter to the editorcomment on a prieto s 1996 paper late quaternary vegetational and climatic changes in the pampa grassland of argentina

large scale washover sedimentation in a freshwater lagoon from the southeast australian coast sea level change tsunami or exceptionally large storm a distinct lens of marine sand up to 90 cm thick confined vertically by peat is found in the upper fill of a closed freshwater back barrier lagoon on the southeast australian coast coring of the deposit suggests it extends continuously up to 600 m inland and tapers landward rising to 1 6 m above principle datum in places the sand is overlain by accumulations of organic rich silt that contain charophytes indicating re estab lishment of lagoon conditions hypotheses considered for the deposition of the sandsheet are higher holocene sea level storms and tsunami ground penetrating radar transects of the seaward dune system suggest a penecontemporaneous erosional contact between a series of truncated pre event dunes and several small over lying post event dunes dating the sandsheet was problematic but it is confined to the last 800 years the young age combined with a lack of associated beach deposits and evidence of wave scouring suggest that a higher sea level hypothesis is unlikely this sand lens is attributed to a large scale washover event from the southeast based on comparisons with modern storm deposits from the same coast and sedimentological diagnostic crite ria derived from studies of modern storm and tsunami deposited sandsheets it is concluded that this sand deposit is the product of a short lived large scale overwash event attributed to a late holocene tsunami

depositional facies of late pleistocene heinrich events in the labrador sea late pleistocene heinrich ice rafting events produced layers rich in ice rafted debris in major parts of the north atlantic north of 40 n a high detrital carbonate content points to the hudson strait outlet of the laurentide ice sheet as a dominant source of the icebergs heinrich events were coupled with short term climate fluctuations during the last and penultimate glaciations and provide evidence for cryosphere hydrosphere atmosphere interaction in pleistocene climate change an unsolved problem with heinrich layers has been their high concentration of fine grained detrital carbonate 80 of the total detrital carbonate which cannot have been delivered by icebergs alone we propose combinations of different processes that deposited four sedimentologically different types of heinrich layers ice rafting alone for the coarser sand to gravel sized fractions and the fine fractions in distal regions type iv heinrich layers whereas nepheloid flows deposited the bulk of the fine sediment in regions proximal to the hudson strait type i heinrich layers on the labrador slope turbidity currents spilling over from canyons were also involved in transporting the fine grained carbonate rich material causing an alternation of mud turbidites and thin laminae of ice rafted debris in type ii heinrich layers on the levees of the northwest atlantic mid ocean channel the thickness relationship is reversed mud turbidites deposited by occasional spillover of currents from the channel are thin and alternate with thicker laminae of ice rafted debris type iii heinrich layers

detrital carbonate rich sediments northwestern labrador sea implications for ice sheet dynamics and iceberg rafting heinrich events in the north atlantic much of the bed of the central and eastern sectors of the laurentide ice sheet was underlain by paleozoic carbonates we propose that pulses of detrital carbonate rich sediments in two cores from the northwestern labrador sea reflect episodes when an ice stream from the hudson strait extended to the shelf break and delivered sediment onto the slope and deep sea plain atomic mass spectroscopy 14 c dating of planktonic foraminifera in cores hu75 009 iv 55 2 4 km water depth and hu87 033 009 1 4 km water depth and 150 km north northwest indicates that the youngest event occurred between ca 14 and 15 ka and another occurred between 19 and 21 ka the two carbonate intervals in northwestern labrador sea cores are coeval with heinrich events 1 and 2 in the eastern north atlantic lat 45 50 n long 20 w where they are associated with an increase in lithic fragments and a drastic reduction in the numbers of foraminifera these changes have been linked with the massive production of icebergs associated with ice sheet surges our evidence indicates that heinrich events 1 and 2 are associated with the dynamics of the hudson strait ice stream and denote considerable glaciological instability

distinguishing tsunami and storm deposits an example from martinhal sw portugal abstract geological identification of past tsunamis is important for risk assessment studies especially in areas where the historical record is limited or absent the main problem when using the geological evidence is to distinguish between tsunami and storm deposits both are high energy events that may leave marine traces in coastal stratigraphic sequences at martinhal sw portugal both storm surge and tsunami deposits are present at the same site within a single stratigraphic sequence which makes it suitable to study the differences between them excluding variations caused by local factors the tsunami associated with the lisbon earthquake of november 1st 1755 ad had a major impact on the geomorphology and sedimentology of martinhal it breached the barrier and laid down an extensive sheet of sand as described in eyewitness reports besides the tsunami deposit the stratigraphy of martinhal also displays evidence for storm surges that have breached and overtopped the barrier flooding the lowland and leaving sand layers both marine derived flood deposits show similar grain size characteristics and distinctive marine foraminifera the most important differences are the rip up clasts and boulders exclusively found in the tsunami deposit and the landward extent of the tsunami deposit that everywhere exceeds that of the storm deposits identification of both depositional units was only possible using a collection of different data and extensive stratigraphical information from cores as well as trenches

evidence for 17th century tsunamis generated on the kuril kamchatka subduction zone lake tokotan hokkaido japan abstract in the seventeenth century two tsunamis that were generated by earthquakes on the kuril kamchatka subduction zone inundated the eastern coast of hokkaido northern japan stratigraphic evidence for these two tsunamis and related land level change in coastal hokkaido consists of two landward thinning sand layers in the sediments of lake tokotan a coastal lagoon on the hokkaido coast the marine origin of these sand layers is indicated by the presence of brackish marine diatoms the rarity and high degree of fragmentation of diatom valves suggests that the sands were transported in a short time over a considerable distance tsunamis at this site were probably generated by great earthquakes along the kuril kamchatka trench volcanic ash deposits lying just above the sands suggest that tsunamis occurred in the late 17th century tsunamis during the historic period are not recorded in lake tokotan which suggests that the sand layers were deposited by tsunamis substantially larger than historic tsunamis

a pb isotope tracer of ocean ice sheet interaction the record from the ne atlantic during the last glacial interglacial cycle abstract ice sheet ocean interactions are both a response to climate forcing and a source of climate feedback releasing freshwater to the surface ocean and influencing climate and atmospheric co2 through changes in ocean circulation documenting the outcomes of these interactions for recent glacial cycles is important given current and future scenarios of polar ice retreat however this is currently hampered by lack of accurate constraints on ice sheet development and demise marine sedimentary pb isotope records have potential to investigate these aspects of ice sheet feedbacks at high temporal resolution because of the sensitivity of the pb isotope composition to continental weathering intensity and solute flux here we present a pb isotope record sourced from the femn oxyhydroxide fraction in marine sediments from odp site 980 on feni drift 2168 mbsl rockall trough ne atlantic spanning the last 43 ka the location of site 980 at the northern edge of the british irish ice sheet biis makes it well placed to monitor changes in biis development as it responded to migration of the polar front during the last glacial interglacial cycle the data reveal millennial scale cyclicity in pb isotope composition reminiscent of dansgaard oeschger cycles from the start of the record until heinrich event 2 43 24 ka characterised by extreme shifts to radiogenic compositions i e variation in 206pb 204pb from 18 9 to 20 5 the period 24 17 5 ka is also characterised by exceptionally radiogenic and highly variable pb isotope compositions associated with the rapid and repeated expansion and collapse of the biis the presence of such radiogenic pb isotope compositions during periods of maximum ice sheet activity support interpretation of the subglacial environment as an active weathering environment contributing to biogeochemical cycles through the transport vectors of meltwater release and debris laden ice calving

traces of tsunami preserved in inter tidal lacustrine and marsh deposits some examples from northeast japan the japan sea earthquake of may 26 1983 triggered a large scale tsunami that surged over the coast of ne japan and caused considerable damage the tsunami resulted in peculiar sedimentary processes on the coast depending on the hydraulic scale of the tsunami three kinds of sedimentary processes were recognized each of which left unique deposits such deposits are expected to remain in sedimentary sequences preserving remarkable sedimentary facies borehole samples drilled at different localities in coastal regions have been examined to detect traces of ancient tsunamis sedimentological and geochemical studies of the samples reveal that layered deposits similar to those developed by the tsunami of the japan sea earthquake are common in the drilled cores estimated ages of these deposits are exactly equivalent to the dates of ancient tsunamis documented in historical records these results show that the invasion of tsunamis is recorded in coastal depositional sequences from analyses of long borehol

shelf erosion and glacial ice proximity in the labrador sea during and after heinrich events h 3 or 4 to h 0 as shown by foraminifera

provenance of heinrich layers in core v28 82 northeastern atlantic 40ar 39ar ages of ice rafted hornblende pb isotopes in feldspar grains and nd sr pb isotopes in the fine sediment fraction abstract several correlatable layers of sediment rich in ice rafted grains have been documented in the north atlantic the most notable within the last glacial cycle are the heinrich layers layers extremely rich in ice rafted detritus and generally barren of foraminifera within the north atlantic ice rafted detritus ird belt the view of these layers is that they represent events where great armadas of icebergs were launched into the north atlantic the importance of the heinrich layers lies in their connection with abrupt climate change in the north atlantic and perhaps globally there is a growing number of published provenance studies of the heinrich layers in the north atlantic based on a variety of methods however there is little overlap of methods applied to the same samples in this contribution we present a multi component provenance study of heinrich layers h1 h2 h4 and h5 from core v28 82 in the eastern north atlantic our results indicate that virtually the entire inventory of terrigenous clastic detritus in heinrich layers h2 h4 and h5 came from ancient continental sources surrounding the labrador sea although heinrich layer h1 is similar in many respects it appears to have some significant differences relative to the other three

the tsunami hypothesis comparisons of the field evidence against the effects on the western australian coast of some of the most powerful storms on earth the tsunami hypothesis proposes that prehistoric tsunamis may have been larger than historic ones along coasts normally historically not associated with major tsunamis the evidence for the hypothesis rests with the types of unusual sedimentary deposits and erosional forms along coasts where the largest historic and prehistoric storm waves do not appear capable of forming the features this is especially the case at locations where boundary conditions i e offshore water depth coastal geomorphology and meteorological limitations are not conducive to the propagation of sufficiently large storm waves at the shore the tsunami hypothesis has been barely debated in the literature this is despite the view of some who suggest that storms have been overlooked or underestimated as a cause few comparisons have been made of the supposed tsunami generated features and the impacts on coasts of extreme intensity storms four of the most powerful tropical cyclones anywhere in the world in recent times struck the western australian coast between 1999 and 2002 the results of post event surveys of these storms showed that none of them produced the enigmatic forms attributed elsewhere to tsunamis

evidence from 40ar 39ar ages for a churchill province source of ice rafted amphiboles in heinrich layer 2 40ar 39 ar ages of most single ice rafted amphiboles from heinrich layer 2 h2 from a core in the labrador sea a core in the eastern north atlantic and a core in the western north atlantic range from 1600 to 2000 ma this range is identical to that for k ar ages from the churchill province of the canadian shield that outcrops at hudson strait and forms the basement of the northern part of hudson bay the ambient glacial sediment includes some younger and older grains derived from paleozoic mesoproterozoic and archean sources but still the majority of the amphiboles have ages in the 1600 2000 ma interval the ca k ratios of these 1600 2000 ma old amphiboles however have a bimodal distribution in contrast with the uniformity of the ca k ratios of h2 amphiboles this indicates that 1600 2000 ma old amphiboles of the ambient sediment were derived from an additional early proterozoic source besides churchill province in h2 churchill derived grains constitute 20 40 of the ice rafted debris ird the fraction in the ambient glacial sediment is 65 80 results presented here are consistent with the hypothesis that heinrich events were produced by a sudden intensification of the iceberg discharge through hudson strait that mixed in the north atlantic with icebergs that continued to calve from other ice sheets the shift from mixed sources in the background sediment to a large dominance of churchill province grains in h2 indicates that even if calving of other ice sheets intensified during the heinrich episode the increase in the iceberg discharge via hudson strait from the hudson bay drainage basin of the laurentide ice sheet was by far the largest

the sedimentology of middle holocene tsunami facies in northern sutherland scotland uk abstract lagoonal sediments attributed to the main holocene marine transgression in strath halladale northern sutherland contain a complex coarser layer believed to have been deposited during the tsunami associated with the second storegga slide off south west norway the coarser sequence is dated at between 7590 50 and 7290 50 radiocarbon years bp 6507 6260 cal bc and 6228 6029 cal bc detailed stratigraphical analysis has determined a distinctive suite of sedimentary sub units within the coarser layer in marked contrast to the sediments which occur above and below a pronounced erosional unconformity with the underlying sediments is recorded with the base of the tsunami layer characterised by eroded material from the underlying peat the presence of a mixed diatom assemblage although fragmentary indicates a chaotic accumulation of the deposit with all habitats represented variations in particle size within the sequence disclose striking similarities with those from contemporary tsunami deposits the run up of the tsunami sediments is calculated at a minimum of 4 6 m this is the first occasion on which a deposit of the second storegga slide tsunami has been found outside the north sea basin and indicates that the area affected by the tsunami may have been larger than has been previously described

sedimentology of rocky shorelines 1 a review of the problem with analytical methods and insights gained from the hulopoe gravel and the modern rocky shoreline of lanai hawaii abstract hypotheses advanced concerning the origin of the pleistocene hulopoe gravel on lanai include mega tsunami abandoned beach multiple event rocky shoreline and for parts of the deposit native hawaiian constructions and degraded lava flow fronts uplift of lanai shorelines has been suggested for deposits occurring up to at least 190 m these conflicting hypotheses highlight problems with the interpretation of coarse gravel deposits containing marine biotic remains the geological records of the processes implied by these hypotheses should look very different discrimination among these or any other hypotheses for the origins of the hulopoe gravel will require careful study of vertical and lateral variations in litho and biofacies facies architecture contact relationships and stratal geometries of this deposit observations of modern rocky shorelines particularly on lanai adjacent to hulopoe gravel outcrops have shown that distinctive coarse gravel facies are present several of which occur in specific geomorphic settings tectonic isostatic and eustatic changes which cause rapid shoreline translations on steep slopes favour preservation of former rocky shorelines and associated sedimentary deposits both above and below sea level the sedimentary record of those shorelines is likely to be complex the modern rocky shoreline sedimentary environment is a hostile one largely neglected by sedimentologists a range of high energy processes characterize these shorelines long period swell tsunami and storm waves can erode hard bedrock and generate coarse gravel they also erode older deposits depositing fresh ones containing mixtures of materials of different ages additional gravelly material may be contributed by rivers draining steep hinterlands to fully evaluate rocky shoreline deposition in the broadest sense for both the hulopoe gravel and other deposits sedimentary facies models are needed for rocky shorelines occurring in a range of settings recognition and description of rocky shoreline deposits are crucial for correctly interpreting the geological history of oceanic and volcanic arc islands for distinguishing between ancient tsunami and storm deposits and for interpreting coarse grained deposits preserved on high energy coasts of continents problems include not only the absence of appropriate sedimentary facies models linking rocky shoreline deposits and environments but also until recently lack of a systematic descriptive scheme applicable to coarse gravel deposits generally two complementary methods serve to integrate the wide range of bed and clast attributes and parameters which characterize complex coarse gravel deposits the composition and fabric caf method has a materials focus providing detailed description of attributes of the constituent clasts petrology the proportions of gravel sand and mud and the ways in which these materials are organized the sedimentary facies model building fmb method emphasizes the organization of a deposit on a bed by bed basis to identify facies and infer depositional processes the systematic use of a comprehensive gravel fabric and petrography log gfpl in conjunction with detailed vertical profiles provides visual representations of a range of deposit characteristics criteria useful for distinguishing sedimentary facies in the hulopoe gravel are grain size modes amount of matrix bed geometry sedimentary structures bed fabric and clast roundness

continuous lake sediment records of glaciation in the sierra nevada between 52 600 and 12 50014c yr b p the chemistry of the carbonate free clay size fraction of owens lake sediments supports the use of total organic carbon and magnetic susceptibility as indicators of stadial interstadial oscillations owens lake records of total organic carbon magnetic susceptibility and chemical composition of the carbonate free clay size fraction indicate that tioga glaciation began 24 500 and ended by 13 60014c yr b p many of the components of glacial rock flour e g tio2 mno bao found in owens lake sediments achieved maximum values during the tioga glaciation when valley glaciers reached their greatest extent total organic carbon and sio2 amorphous concentrations reached minimum values during tioga glaciation resulting from decreases in productivity that accompanied the introduction of rock flour into the surface waters of owens lake at least 20 stadial interstadial oscillations occurred in the sierra nevada between 52 600 and 14 00014c yr b p total organic carbon data from a pyramid lake sediment core also indicate oscillations in glacier activity between 39 500 and 13 60014c yr b p alpine glacier oscillations occurred on a frequency of 1900 yr in both basins suggesting that millennial scale oscillations occurred in california and nevada during most of the past 52 600 yr

mid wisconsin laurentide ice sheet growth and decay implications for heinrich events 3 and 4 a close look at the sedimentology of heinrich event 4 from the northwest labrador sea indicates that an extended ice margin perhaps greater than before heinrich events 1 or 2 h 1 and h 2 existed in the hudson strait region pre heinrich event 4 h 4 and that on the basis of characteristics of the sediment unit heinrich event 4 was different than heinrich events 1 or 2 i e larger ice sheet collapse longer duration dirtier icebergs other data from across the southern and eastern margin of the laurentide ice sheet as well as greenland and the north atlantic support this interpretation possibly indicating a relative mid wisconsin glacial maximum pre heinrich event 4 many of these data also indicate that heinrich event 4 35 ka resulted in serious climatic and oceanographic reorganizations we suggest that heinrich event 4 gutted the hudson strait leaving it devoid of ice for heinrich event 3 we further hypothesize that heinrich event 3 did not originate from axial ice transport along the hudson strait thus heinrich event 3 may be more analogous to the proposed northward advancing ice from ungava bay during heinrich event 0 than to the more typical down the strait flow during h 1 h 2 and h 4 consequently the climatic and oceanographic impacts resulting from heinrich events are highly susceptible to the type origin and magnitude of ice sheet collapse something which varied per heinrich event during the last glacial period

continental weathering fluxes during the last glacial interglacial cycle insights from the marine sedimentary pb isotope record at orphan knoll nw atlantic abstract regional weathering intensity must have changed dramatically at high latitudes during the quaternary as a consequence of repeated continental glaciation investigation of these glacial interglacial changes at high temporal resolution is possible with the recent development of pb isotopes in femn oxyhydroxide phases as a proxy for region specific weathering intensity where increases in the radiogenic component are thought to correspond to increased continental weathering fluxes here we present a pb isotope record sourced from the femn oxyhydroxide fraction in marine sediments from iodp sites u1302 3 on orphan knoll 3500 mbsl nw atlantic spanning the last 37 ka located at the eastern edge of the laurentide ice sheet lis site u1302 3 is well placed to monitor changes in weathering intensity associated with lis glacial history overall the data show a close correspondence to local surface water 18o with least radiogenic values during times of heavy 18o glacial maximum and most radiogenic values during times of light 18o holocene this supports the prediction that weathering intensity in glaciated regions of the north atlantic correlates with the exposure age of glacial debris superimposed on these background trends are extreme radiogenic excursions e g variation in 206pb 204pb from 19 2 21 0 contemporaneous with heinrich events and the younger dryas these data are substantially more radiogenic than existing records from the nw atlantic and most likely represent episodes of exceptionally high inputs of pre formed femn oxyhydroxides during drainage of the lis due to its extreme isotope composition at least in the nw atlantic region pb would appear to be a good proxy for the fluxes of weathered continental material and perhaps by inference nutrients to the surface ocean

sedimentology of rocky shorelines 2 shoreline megaclasts on the north shore of oahu hawaii origins and history abstract limestone megaclasts up to 96 t in weight rest on a coastal rock platform near sunset beach on the north shore of oahu hawaii they occur in seaward dipping imbricate clusters and as solitary clasts the rock platform is subject to large swell waves and very large waves associated with winter storms and tsunami a series of photographs covering the period from ca 1905 to 1996 show episodic rearrangement of megaclasts on the platform and the appearance of new megaclasts near the platform edge the largest solitary megaclast ca 96 t was emplaced on the platform between 1940 and 1950 possibly by the 1946 aleutian tsunami and has moved twice since then in ca 30 m jumps along two different trajectories larger clasts have been broken from the platform edge and emplaced on the platform only by very large wave events whereas formation and movement of smaller tabular clasts ca 30 40 t appear to be a continuously ongoing process on the surface of the rock platform partial detachment of clasts by marine erosion processes along joints and cracks in the limestone bedrock facilitates their complete detachment from both the platform edge and platform surface the larger numbers of megaclasts emplaced on the north and northwest sectors of the platform relative to other sectors are attributed to exertion of maximum wave power on these sectors due to a combination of steep slope and ramp like submarine topography

geomorphological effects of tsunami run up and backwash abstract geomorphological processes associated with tsunami run up and backwash are highly complex to date most studies have considered the sedimentology of palaeo tsunamis while almost no detailed studies have been undertaken in areas known to have been affected by tsunamis in recent times research on contemporary tsunamis show that coastal landscapes may be greatly altered not only by direct tsunami run up orthogonal to the shoreline but also by episodes of vigorous backwash and by water flow sub parallel to the coastline the combined effect of these processes produces hitherto unrecognised coastal landforms that are dominated by the effects of high magnitude erosion and deposition deposition of large boulders is also associated with severe tsunamis while in adjacent areas run up processes often result in the deposition of continuous and discontinuous sediment sheets in many instances the upper limit of sediment deposition lies well below the upper limit of wave run up which is frequently marked by a well defined zone of stripped vegetation and soil the processes described have considerable implications for models of coastal evolution it may even be the case that the evolution of particular stretches of coastline are dominated by such high magnitude low frequency events

coastal sedimentation associated with the december 12th 1992 tsunami in flores indonesia this paper presents the result of a detailed granulometric investigation of sediments deposited by a modern tsunami the 1992 tsunami in flores indonesia eyewitness accounts indicate that sediments were deposited upon coastal lowlands over wide areas as a result of the tsunami inundation distinctive vertical and lateral variations in particle size composition are characteristic features of the tsunami deposits and these are intimately related to sedimentary processes associated with flood inundation the geomorphological and sedimentary evidence is used here to establish a preliminary model of tsunami sedimentation this information is believed to be of great value in understanding sedimentary processes associated with tsunami flooding and in the interpretation of palaeo tsunami deposits

glacial geology of western hudson strait canada with reference to laurentide ice sheet dynamics hudson strait is a large marine trough that connected the marine based interior of the laurentide ice sheet with the ocean field investigations of the glacial geology of western hudson strait have helped to define the role of the strait in laurentide ice sheet dynamics in general ice converged on western hudson strait from the north west and south upon reaching the strait ice flowing from foxe and ungava peninsulas turned eastward within less than 10 km of the coast to parallel eastwardly flowing ice in the strait glacial erosion of western hudson strait is identified as slight the texture carbonate content ph and the presence of several types of erratics distinguish till on nottingham salisbury and mill islands in western hudson strait from till on southern foxe peninsula and northern ungava peninsula till on the islands is characterized by higher ph and higher proportions of silt clay and carbonate than till on either adjacent peninsula in addition the presence of red sandstones porphyritic intrusives stromatolites omarolluks and iron formation are restricted to the islands with few exceptions that can be explained by ice rafting carbonate is present in the pebble and boulder fractions of till on foxe peninsula and in all fractions of till on the islands but is absent from till on ungava peninsula these data suggest that ice from distant and widely distributed source regions affected western hudson strait and along with evidence for a rapid change in ice flow direction along the margins of hudson strait suggest that the strait was occupied by a relatively fast moving ice stream that had a substantial impact on the interior of the ice sheet through downdraw

abrupt changes heinrich events in late quaternary north atlantic marine environments a history and review of data and concepts in the last several years evidence has mounted that a series of abrupt changes in sediment delivery and palaeoceanography effected the north atlantic they are recorded in a variety of proxy records but most dramatically in changes of grain size and mineralogy associated with postulated iceberg rafting events specifically heinrich h events this review paper examines the evidence for such evidence prior to the development of the heinrich event concept 1988 1992 and then examines the explosion of data and correlations that stemmed from the acceptance and use of this paradigm specific attention is focused on ideas pertaining to the cause s of glaciological mechanisms sediment delivery and sediment source and major gaps in our understanding of the underlying glaciological glacial geological and glacial marine processes are stressed abrupt changes across boundaries associated with h 2 in the labrador sea are illustrated from core hu87033 009lcf the case is made that correlations between records need to be more rigorous especially within the range of radiocarbon dating but it appears that abrupt changes in the delivery of iceberg rafted debris which characterize these intervals are multisourced it is unclear how global climate can simultaneously influence the abrupt behaviour of ice margins in different parts of the world for marine based margins changes in relative sea level are one possibility a qualitative model is presented for triggering h events which includes global changes in mass balance changes in relative sea level at ice margins due to glacial isostasy and changes in the basal thermal regime of tidewater ice streams 1998 john wiley sons ltd

geological and historical records of tsunami in australia abstract the indian ocean tsunami iot of 2004 has resulted in significant interest within australia about the record of tsunami for the continent because an understanding of tsunami hazard begins with a catalogue of past events here a preliminary catalogue of tsunami affecting australia is presented the catalogue contains entries for 57 tsunami events the oldest event is dated at 3 47 ga the most recent is the july 17th 2006 forty four tsunami were recorded on the new south wales coast although the nw coast of western australia records a significant number of events forty seven events have affected australia since ad1858 maximum run up for an historic event is 6 m asl whilst the maximum run up for a palaeotsunami event is reported at an elevation of at least 100 m asl twenty three percent of historic australian tsunami were generated by unknown causes and papua new guinea the solomon islands and indonesia collectively represent the most important source area of historic tsunami for australia geological records for palaeo and historic tsunami are identified and summarised the geological record of tsunami represents a potentially important source of information for australian tsunami however at the present time the geological record is both limited and controversial and future research should seek to re examine proposed geological evidence of tsunami from an analysis of this preliminary catalogue of australian tsunami a series of key research priorities have been identified to guide future research in the region

evaluating the impacts of huge waves on rocky shorelines an essay review of the book tsunami the underrated hazard abstract tsunami the underrated hazard draws together and summarizes a wealth of information about the nature impacts and causes of tsunamis written from a natural hazards perspective the book stresses that large tsunamis can affect even protected coasts that have not experienced large tsunamis historically many deposits and erosional features described and discussed as tsunami signatures have yet to be linked specifically with tsunamis cited references in the book do not necessarily support a tsunami origin for these features because accepted scientific citation practices have not been followed although rocky shorelines in southeastern australia the hawaiian islands and elsewhere generate and preserve a variety of boulder and block deposits and erosional features their sediment dynamics and geomorphology are poorly studied and unequivocal criteria for distinguishing between deposits of storms and tsunamis have yet to be developed despite its shortcomings this book should be on the library shelves of all marine geoscientists who study modern and ancient shorelines however it should be used with great circumspection because the process product relationships it assumes are equivocal

late quaternary detrital carbonate dc layers in baffin bay marine sediments 67 74 n correlation with heinrich events in the north atlantic abstract episodes of glaciation in the region north of baffin bay resulted in the erosion of paleozoic carbonate outcrops in nw greenland and the canadian high arctic these events are recognized in the marine sediments of baffin bay bb as a series of detrital carbonate rich dc layers bbdc layers thin southward within baffin bay thus the contribution of baffin bay ice rafted carbonate rich sediments to the north atlantic is probably slight especially compared with sediment output from hudson strait during heinrich events we reexamine cf aksu 1981 a series of nine piston cores from the axis of baffin bay and across the davis strait sill and provide a suite of 21 ams 14 c dates on foramininfera which bracket the ages of several dc layers the onset of the last dc event is dated in six cores and has an age of ca 12 4 ka in northern and central baffin bay a thick dc layer occurs at around 4 m in the cores and is dated 40 ka there were three to six dc intervening events the youngest bbdc event possibly a double event lags heinrich event 1 h 1 off hudson strait dated at 14 5 ka but it is coeval with the pronounced warming seen in gisp2 records from the greenland ice sheet during interstadial 1 we hypothesize that bbdc episodes are coeval with major interstadial 18 o peaks from gisp2 and other greenland ice core records and are caused by or associated with the advection of atlantic water into baffin bay cf hiscott et al 1989 and the subsequent rapid retreat of ice streams in the northern approaches to baffin bay

iceberg production debris rafting and the extent and thickness of heinrich layers h 1 h 2 in north atlantic sediments the pattern of heinrich layer distribution for the last two events h 1 14 5 and h 2 21 1 ka mapped from magnetic susceptibility analysis of more than 50 north atlantic ocean cores provides the most detailed information to date on their extent and thickness an integrated spatial average thickness for the layers is 10 15 cm and there is a strong distance decay eastward the pattern of deposition over the north atlantic is similar for events h 1 and h 2 indicating that icebergs followed similar drift tracks rates of iceberg production and sediment flux from the hudson strait drainage basin of the north american laurentide ice sheet the major iceberg source for the events were calculated by using a mass balance approach this provides an envelope of sedimentation rates and the prediction that it would take between 50 and 1250 yr of iceberg sediment delivery to accumulate a heinrich layer averaging 10 cm thick over the north atlantic depending on the model assumptions used the most likely duration of heinrich events is 250 1250 yr

tsunami and palaeotsunami depositional signatures and their potential value in understanding the late holocene tsunami record in recent years much research on modern and palaeotsunami deposits has been published from these studies a range of signature types has been identified identifying and dating such deposits is an important element in understanding late holocene tsunami hazard and risk however important questions such as do modern and palaeotsunami leave similar or dissimilar traces do tsunami leave the same signatures all around the world or are there significant variations and what is the actual record of tsunami in different parts of the world still remain answering these questions is not an easy task but examining megatsunami flood deposits should shed some light on these questions because such high magnitude events should leave very clear and detailed traces within the coastal landscape the coast of se australia is reported to have been affected by numerous palaeomegatsunami in the late holocene as such the coast of new south wales offers an important natural laboratory to examine in detail deposits associated with such events here we summarize the published characteristics of modern and palaeotsunami deposits globally and within australia we briefly outline the tsunami risk to australia before examining a site called minnamurra point on the coastline of se australia south of sydney that has previously been described as containing evidence for a palaeomegatsunami of an unknown age we describe the results of a detailed coastal survey field stratigraphic investigation and various standard laboratory analyses surprisingly we are unable to replicate the previously reported findings of tsunami deposits whilst we prefer the interpretation that the sequence is an in situ soil the sediment sequence examined contains none of the usually reported lines of evidence to demonstrate tsunami provenance we recognize and discuss the significance and difficulty of identifying tsunami deposits in the field and consider the implications of our findings to the wider debate about the preservation of tsunami deposited sediments

climatic oscillations 10 000 155 000 yr b p at owens lake california reflected in glacial rock flour abundance and lake salinity in core ol 92 earlier wetter cycles the lake overflowed to fill a series chemical analyses of the acid soluble and clay size fractions of of downstream basins including china lake basin searles sediment samples 1500 yr resolution reveal oscillations of lake valley panamint valley and ultimately death valley salinity and of glacial advances in core ol 92 back to 155 000 yr smith and street perrott 1983 in 1992 the u s geological b p relatively saline conditions are indicated by the abundance survey drilled a 323 m deep core ol 92 into owens lake of carbonate and smectite both pedogenic and authigenic re sediments near the depocenter of the basin to obtain a continflected by ca sr and mg in the acid soluble suite and by cs2o uous record of silty clay sediment spanning the last 800 000 excess mgo and loi loss on ignition in the clay size fraction yr a multiparameter reconnaissance study of the entire core rock flour produced during glacial advances is represented by ca 7000 yr resolution reported in a 13 chapter summary the abundance of detrital plagioclase and biotite in the clay size volume smith and bischoff 1997 revealed cycles characfraction the ratio of which remains essentially constant over the terized by closed and overflowing lake conditions entire time span these phases are quantitatively represented by na2o tio2 ba and mn in the clay fraction the rock flour record we report here the results of a second part of an intermediindicates two major ice advances during the penultimate glacial ate resolution study aimed at resolving shorter term events cycle corresponding to marine isotope stage mis 6 no major over just the past 155 000 yr using sediment samples of ca advances during the last interglaciation entire mis 5 and three 1500 yr resolution taken over the uppermost 90 m of olmajor advances during the last glacial cycle mis 2 3 and 4 92 the companion study menking et al 1997 reports on the ages of the latter three correspond rather well to 36 cl dates grain size tic total inorganic carbon content and stable reported for sierra nevada moraines the onset of the last intergla isotopic measurements proxies which tend to reflect variaciation is shown by abrupt increases in authigenic caco3 and an tions in water flow and which are most representative of abrupt decrease in rock flour at about 118 000 yr b p according variations during closed lake conditions the present study to our time scale in contrast the boundary appears to be gradual was concerned primarily with seeking a proxy for glacial in the d 18 o record in which the change from light to heavy values advances we found that the mineralogy and chemistry of begins at about 140 000 yrs b p the exact position of the termination therefore may be proxy dependent conditions of high car the clay fraction provide indices of glacial rock flour we bonate and low rock flour prevailed during the entire period from also report on the composition of the acid soluble carbonate 118 000 yr b p until the glacial advance at 53 000 yr b p signaled fraction which gives further detail on closed lake conditions

smooth or oscillating late holocene sea level curve evidence from cross regional statistical regressions of fixed biological indicators abstract what if any is the pattern of change of the late holocene sea level curve if a common pattern exists can it be better discerned in the non glaciated tectonically stable regions of the southern hemisphere and is sea level data more reliable from one type of marine sample than another to begin an investigation of these questions we present a review of regressing time elevation plots from the low to mid latitudes of the southern hemisphere based upon the differential between modern and past levels of various fixed biological indicators mainly calcareous tubeworms and corals stranded up to 2 m above present relative sea levels the sample sets come from our work in southeast australia and comparable work from north east australia the pacific islands and brazil we show that using evidence obtained from fixed intertidal tubeworm species there is no statistical exclusivity between the smooth and oscillating polynomials but corals are more problematic in situ tubeworm species with their reduced error bars in comparison to corals fulfil the condition of providing more robust results for statistical analysis regression curves based on these species point to cross regional similarities in the pattern of sea level movement of the last 6000 years across the lower latitudes of the southern hemisphere these statistical exercises while not able to yield definitive conclusions can highlight statistically equally likely alternative patterns of sea level movement which can then be tested by field evidence they can also give useful indications of the quality of sea level data obtained from different biological sources as in the difficulties in the use of corals compared to common intertidal tubeworm species

smooth or oscillating late holocene sea level curve evidence from the palaeo zoology of fixed biological indicators in east australia and beyond abstract the nature of late holocene sea level change has important palaeo environmental implications for the understanding of past and present coastal oceanic and climatic systems this study develops a fixed biological indicator fbi method based on tubeworm barnacle assemblages in order to construct a late holocene sea level curve for south east australia it also compares changes within and between mid latitude regions of the southern hemisphere using the palaeo biology of inter tidal sub fossils that have provided time elevation data covering the past 5000 years five sites from around the mouth of the port hacking estuary 29 km south of sydney are described in detail the results suggest that rather than relative sea level describing a stable or smoothly falling pattern from a maximum of 1 0 m above present over the last 5000 years on the southeast australian coast there have been complex movements from a maximum of over 1 5 m with at least one marked fall between 3500 and 3400 yr bp and the possibility of a small positive oscillation around 1900 yr bp furthermore changes in the inter tidal species at our sites suggest that there was a period between 4300 and 2800 years where ocean temperatures were warmer than present our port hacking findings are compared with other studies from the east coast of australia as well as the pacific islands and brazil evidence from each location suggests a broad similarity in the timing of environmental events and marine fluctuations across an expanse of the southern hemisphere are such similarities coincidental or part of mechanisms common to mid latitude southern hemisphere regions

changes in sea surface hydrology associated with heinrich event 4 in the north atlantic ocean between 40 and 60 n abstract the changes in distribution of sea surface temperature and salinity in the north atlantic between 40 and 60 n were reconstructed for the time interval between 40 and 30 kyr bp which includes the large iceberg discharge event associated with the deposition of heinrich layer 4 we found that the meltwater input during deposition of heinrich layer 4 resulted in a 1 2 kyr temperature decrease of about 2 c and a salinity decrease in the range of 1 5 3 5 between 40 and 50 n sites above 50 n did not experience significant salinity variations a much larger area was affected by the reduction in sea surface temperature the amplitude of the sea surface temperature shift was however much smaller than the atmospheric temperature changes over greenland at gisp and grip sites

evidence for massive discharges of icebergs into the north atlantic ocean during the last glacial period sediments in the north atlantic ocean contain a series of layers that are rich in ice rafted debris and unusually poor in foraminifera1 here we present evidence that the most recent six of these heinrich layers deposited between 14 000 and 70 000 years ago record marked decreases in sea surface temperature and salinity decreases in the flux of planktonic foraminifera to the sediments and short lived massive discharges of icebergs originating in eastern canada the path of the icebergs clearly marked by the presence of ice rafted detrital carbonate can be traced for more than 3 000 km a remarkable distance attesting to extreme cooling of surface waters and enormous amounts of drifting ice the cause of these extreme events is puzzling they may reflect repeated rapid advances of the laurentide ice sheet perhaps associated with reductions in air temperatures yet temperature records from greenland ice cores appear to exhibit only a weak corresponding signal moreover the 5 10 000 yr intervals between the events are inconsistent with milankovitch orbital periodicities raising the question of what the ultimate cause of the postulated cooling may have been

linking tsunami deposits submarine slides and offshore earthquakes abstract the recognition that many tsunamis are associated with coastal sedimentation has been of great value in the study of tsunamis prehistorically geological investigation of such sediments has resulted in the identification of a series of palaeotsunamis that appear to have taken place in different areas of the world in most cases however it has proved difficult to link former tsunamis to specific source mechanisms studies of modern tsunamis have also faced difficulties in the recognition of the specific source mechanisms for example offshore earthquakes may trigger submarine slides that combine to produce complex patterns of tsunami flooding at the coast

sedimentology of rocky shorelines 3 hydrodynamics of megaclast emplacement and transport on a shore platform oahu hawaii abstract megaclasts of well cemented coralgal limestone have been emplaced onto a shore platform by large waves on the north shore of oahu hi emplacement and movements of the largest ca 96 ton megaclast have been dated using aerial photographs hydrodynamic forces at the low submerged shoreline cliff are computed using design wave characteristics based on linear wave theory and experimental results considering the local wave climate and near shore bottom topography force exerted by a tsunami has been estimated based on the 1946 aleutian tsunami the computed forces are evaluated in terms of the initial fracturing along a given failure plane that is required in order for the detachment to occur the analysis shows that tsunami as well as large swell waves are capable of quarrying the megaclast provided that sufficient initial fracturing is present dislodgement and emplacement most likely occurred in a sequence during impact of a single wave on the shoreline cliff swell waves however are seldom capable of emplacing large blocks onto the platform due to their rapid disintegration after breaking so that most blocks quarried from the cliff edge fall back onto the submarine terrace emplacement of large boulders seems to require extreme sea waves with periods longer than storms or north pacific swells usually produce transport mechanisms on the shore platform vary depending on megaclast shape sliding is a common mechanism of transport for larger and irregular megaclasts whereas somewhat smaller and platy megaclasts are occasionally found in overturned positions

palaeotsunami deposits a new zealand perspective abstract over the past few years geological investigations of coastal sediments in new zealand have provided evidence of past tsunami the identification of palaeotsunami deposits is helping to increase our knowledge about the sources magnitude and frequency of these events this paper briefly outlines both the key diagnostic characteristics used in new zealand to identify palaeotsunami deposits and the emerging findings related to recent research