late quaternary sea levels and crustal movements coastal british columbia late quaternary sea level fluctuations on the british columbia coast have been established from studies of terrestrial and marine sediments and landforms these studies indicate that the sea level history of mainland british columbia and eastern vancouver island is very different from that of the queen charlotte islands and western vancouver island specifically in the former areas there was a rapid rise of submerged coastal lowlands between about 13 000 and 10 000 years ago emergence culminated about 6000 9000 years ago depending on the locality when the sea relative to the land was 12 m or more lower than at present in some areas during middle and late holocene time relative sea level rose on the mainland coast and at least locally on eastern vancouver island resulting in inundation of coastal archaeological sites and low lying terrestrial vegetation tidal records and precise levelling suggest ongoing submergence of at least part of this region in contrast shorelines on the queen charlotte i

lobal interactions rheologic superposition and implications for a pleistocene ice stream on the continental shelf of british columbia abstract data on structures stone striae clast pavements fabrics morphology provenance and matrix grain size of four pre late wisconsinan diamictons are presented from the lower accessible part of an 855 m long sea cliff at cape ball east coast of graham island queen charlotte archipelago british columbia the data indicate that an ice stream crossed the continental shelf from the british columbian mainland to the queen charlotte islands local queen charlotte piedmont ice coalesced with the western edge of the cordilleran ice sheet resulting in northward flow deflection along the east coast of graham island generally consistent structural and stone data indicate that diamictons were deposited as primary subglacial tills and that subglacial dynamics and rheologic conditions were complex two of the tills can be traced continuously over the cape ball section which provides a north south transect oblique to ice flow each of the two tills reveals five major changes in rheology and genesis ranging from a strong lodgement component to dominantly deformation mainly by subglacial squeeze flow true end member tills are rare and in almost all places the tills are hybrids that formed within a continuum of till forming processes commonly involving stone rotation and superposition of structures and rheologic states this could have occurred mainly in response to fluctuating till pore water content along the transect two dimensional stretches of contrasting till types probably represent a three dimensional patchwork of contrasting till rheologies and pore waters if patches of ductily deforming till were common and or widespread they could have accounted for much of the movement of cordilleran ice over glaciomarine mud on the continental shelf when sea level was much lower than present deforming probably saturated muddy till reconstituted glaciomarine would have possessed negligible shear strength resulting in a thin rapidly moving glacier most likely an ice stream that reached cape ball but failed to remove the record of previous glacial events the ice stream probably issued out of the mainland s skeena valley which is aligned with cape ball and is approximately the size of valleys in antarctica that today conduct small outlet glaciers and ice streams evidence for this and other ice streams on the northwestern continental shelf of north america imply that destabilization and rapid decay of the western edge of the cordilleran ice sheet may have been accomplished by a combination of ice streams sea level rise and extensive calving

progressive deformation of the south stack and new harbour groups holy island western anglesey north wales the monian supergroup of western anglesey comprises three major lithostratigraphic units the south stack oldest new harbour and gwna groups in northern and western anglesey deformation and metamorphism each increase in intensity downward through the monian supergroup especially towards the base of the new harbour group the variation in style and apparent intensity of deformation recorded by the south stack and new harbour groups were governed by gross lithological differences a correlation is proposed between the deformation histories of the new harbour and south stack groups early deformation of the supergroup produced a pervasive bedding parallel s1 fabric chlorite in both the new harbour and to a lesser extent south stack groups development of the major se verging f2 penrhyn mawr and rhoscolyn anticlines and associated minor folds also produced an axial planar s2 pressure solution and crenulation cleavage phengite the rhoscolyn anticline was subsequently modified by the localized development of recumbent mesoscale f3 folds with an axial planar pressure solution cleavage phengite to phengitic muscovite the f3 event may have accompanied an episode of thrust faulting deformation of the south stack and new harbour groups was accompanied by a progressive regional greenschist facies metamorphic event the simplest interpretation of the deformation history of the monian supergroup involves a progressive se directed shear event which occurred prior to the deposition of an ordovician overstep sequence on anglesey

middle wisconsinan sediments and paleoecology of central british columbia sites at necoslie and nautley rivers at two sites in central british columbia sediments with dispersed organic matter underneath fraser glaciation deposits are interpreted as nonglacial deposits of middle wisconsinan age olympia nonglacial interval at necoslie river undated sand with dispersed organic matter thought to be fluvial in origin is overlain by fraser drift at nautley river similar sand contains plant detritus that has yielded 14c ages of 38 230 410 bp beta 88557 and 42460 670 bp beta 88558 pollen assemblages of the sediments with dispersed organic matter at the necoslie river and nautley river sites are similar both assemblages are dominated by herb pollen with a lesser amount of tree pollen the pollen assemblages are thought to reflect a tundra type vegetation because vegetation in the area is presently dominated by spruce and subalpine fir forest climate during deposition probably was much cooler than today data presented here support the contention of other studies in western canada that cooler climati

menai strait fault system an early caledonian terrane boundary in north wales a steep fault system runs parallel to the menai strait which separates anglesey from the mainland of north wales the menai strait fault system is interpreted as a major terrane boundary along which terrane docking took place during the late precambrian or earliest cambrian the evidence is based on 1 marked geologic dissimilarities exhibited by the pre late early cambrian basement to these terranes and 2 the existence of early major ductile shear zones within the fault system rocks as varied as blueschists low grade melange and shallow level granitic complexes were juxtaposed along these steep shear zones prior to the eruption of ash flow tuffs and deposition of upper lower cambrian marine sediments in the welsh basin since the amalgamation of the anglesey area with the avalonian terrane then a part of gondwana frequent phanerozoic reactivation of the resulting composite terrane boundary has been restricted to mostly dip slip fault movements

palynology and paleotemperature analysis of the whidbey formation puget lowland washington a series of pollen assemblages and the environments of deposition are shown by samples from 143 levels of interbedded sand silt clay and peaty and woody sediments in sections from the pleistocene whidbey formation at useless bay the type locality west beach point wilson and foulweather bluff deposition of the formation is interpreted to have taken place over a broad floodplain under fluvial conditions where drainage shifted between and into tracts of paludified ground of the four sections studied only useless bay and point wilson contain assemblages with analogs found in the modern pollen rain on the floodplains of the nisqually skokomish and chehalis rivers in western washington q mode factor analysis of pollen percentages in the whidbey samples extracted douglas fir pine alder grass and sedge as the principals for 93 of the data stepwise regression relating modern pollen rain and temperature resulted in a transfer function that when applied to the principals for the whidbey produced mean july temperatures for the intervals represented by the sections temperature curves for useless bay and point wilson show maxima comparable with the modern average of 15 8 c maximum values at west beach and foulweather bluff are approximately 2 lower these curves when compared with curves from late quaternary deposits and the interglacial puyallup and alderton formations indicate that sediments belonging to the whidbey are largely from an interglacial age comparable to the holocene or present interglaciation but also from cooler episodes similar to the late fraser glaciation

depth bed slope and wave climate dependence of long term average sand transport across the lower shoreface abstract we analyse measured 46 year changes in nearshore bathymetry to quantify rates of net shore normal sand transport q x in 10 20 m depths at northern gold coast australia these are significant both in understanding local disequilibrium shoreface evolution and as prototype data that may be used to assess theoretical predictive methods this analysis is feasible because the migration history of a nearby river mouth has formed a disequilibrium shoreface lobe that is evolving towards an equilibrium profile shape which is identified in adjacent non lobe profiles the data include various profile transect surveys from 1966 to 2012 sediment characteristics and locally recorded wave conditions a generally applicable form of q x that is a function of both a depth dependent horizontal bed transport forcing component and bed slope q x q x h s is developed and quantified in terms of long term average behavior for this site dependence of the forcing component on wave climate is shown from higher than average q x derived from the lobe response during a recent five year period with abnormally high waves our q x h s quantifies the balance between generally shoreward wave boundary layer sand transport and the opposing effect of the seabed slope as incorporated in the predictive methods

a possible concealed granite beneath part of anglesey north wales a closed bouguer gravity low is revealed by land and marine gravity survey data centred on holyhead bay northwest anglesey the anomaly extends across areas on land and offshore mainly occupied by precambrian rocks a concealed granite offers the best explanation for the anomaly and a late caledonian age seems most probable for the intrusion although precambrian early cambrian ages are also possible the existence of a granite in this area could have influenced the development of mineralization and the low density rock mass also formed a relatively buoyant core to the basement block it could therefore have been instrumental in the preservation of this precambrian structural high

late pleistocene chronology and paleoclimate of vancouver island determined from cave deposits speleothems from four caves in south central vancouver island have been analysed by the 230th 234u method only speleothems from one cave cascade cave near port alberni contained sufficient uranium for them to be dated twenty seven ages determined for seven speleothems were found to cluster in two periods 67 28 ka corresponding to the olympia interstadial and 23 10 ka or 15 ka if corrected for detrital thorium contamination corresponding to the fraser late wisconsin deglaciation and holocene periods two speleothems were found to be deposited in isotopic equilibrium with their seepage waters profiles of variations in 18o of the calcite 18oc of each of the two deposits show a decrease of 1 3 over the growth period 64 28 ka at all times 18oc was less than 18o of modern calcite in the cave using modern cave temperature and the variation of 18o of seawater over the dated period the profiles of 18oc are interpreted in terms of a paleotemperature record for the olympia interstadial

early wisconsinan mis 4 glaciation on haida gwaii british columbia and implications for biological refugia sea cliffs at cape ball on graham island british columbia expose a thick sequence of pleistocene sediments deposited during at least two glaciations in sequence from the base of the section the units are 1 stony mud 2 till 3 silt sand and peat 4 stony mud 5 laminated sand and silt 6 cross bedded sand and 7 till of special interest is unit 4 a massive to weakly stratified mud containing scattered stones that was deposited during the penultimate pleistocene glaciation marine isotope stage mis 4 this unit contains wood and marine shell fragments that have yielded non finite radiocarbon ages sand and silt with thin stringers of peat unit 3 directly underlie this stony mud and returned an optical age of 57 3 5 7 ka the stony mud is unconformably overlain by ponded sediments unit 5 and advance outwash unit 6 and till unit 7 deposited during the fraser glaciation mis 2 the optically dated unit and a correlative peat and silty sand unit at a nearby exposure have p

structurally controlled hydrocarbon seeps on a glaciated continental margin hecate strait offshore british columbia abstract this paper describes structurally controlled gas seeps and their influence on seafloor morphology at sites within queen charlotte basin qcb a sedimentary basin situated offshore british columbia western canada numerous surficial and shallow sediment features related to both ice cover and shallow gas have been identified in high resolution multichannel seismic huntec deep towed seismic multibeam bathymetry and backscatter and piston core data that were acquired over a 10 km by 10 km grid in an eastern part of qcb pockmarks seafloor mounds and iceberg ploughmarks are visible in the multibeam data small scale folds vertical blank zones and acoustic turbidity are observed in the huntec data the multichannel seismic data show a faulted anticline phase reversed bright spots zones of low instantaneous frequency and velocity pull ups one seafloor mound lies directly above a shallow fault that offsets an asymmetric fold the remaining mounds lie either above or in close proximity to asymmetric folds that are faulted bright spots are observed along some fault traces and within a cut and fill sequence at two way travel times between 0 42 and 1 0 s velocity pull ups are observed in the multichannel data below gas expansion voids present in piston cores backscatter data show that seafloor mounds are highly reflective compared to the surrounding seafloor these observations indicate that gas has been migrating upward through the rock column and expelled into the shallow sediments the shallow gas has been biologically mediated to form carbonate sediments within and around seafloor mounds shallow gas has also deformed surficial sediments into positive relief mounds and negative relief pockmarks

late glacial vegetation dynamics of the queen charlotte islands and adjacent continental shelf british columbia canada abstract ams radiocarbon dates and paleoecological analyses of sediments from the continental shelf between the queen charlotte islands and the british columbia mainland confirm that portions of the shelf were subaerially exposed and ice free between at least 14 330 and 12 860 14c years bp 17 370 14 570 cal years bp pollen analysis suggests that cyperaceae likely formed the dominant plant cover on the exposed shelf at dogfish bank and fossil pediastrum algae confirm the presence of freshwater pollen accumulation rates suggest low plant density on the exposed shelf although this is uncertain due to over and under representation of some pollen types in relation to vegetation abundance on the landscape paleoecological analyses of late glacial sediments at west side pond on the southern queen charlotte islands demonstrate succession from herb tundra dominated by cyperaceae at 13 750 14c years bp 16 830 cal years bp to dwarf shrub tundra with salix and empetrum nigrum after 13 500 14c years bp 16 400 cal years bp pteridophytes increased in abundance during the transition to pinus contorta woodland ca 13 000 14c years bp 15 600 cal years bp fossil conifer stomata suggest that p contorta grew locally as early as 13 040 305 14c years bp alnus crispa was co dominant by 11 500 14c years bp 13 500 cal years bp and picea sitchensis or its hybrids were present as early as 11 400 14c years bp 13 400 cal years bp in the south moresby area

laboratory investigation of the bruun rule and beach response to sea level rise abstract rising sea levels are expected to cause widespread coastal recession over the course of the next century in this work new insight into the response of sandy beaches to sea level rise is obtained through a series of comprehensive experiments using monochromatic and random waves in medium scale laboratory wave flumes beach profile development from initially planar profiles and a 2 3 power law profile exposed to wave conditions that formed barred or bermed profiles and subsequent profile evolution following rises in water level and the same wave conditions are presented experiments assess profile response to a step change in water level as well as the influence of sediment deposition above the still water level e g overwash a continuity based profile translation model ptm is applied to both idealised and measured shoreface profiles and is used to predict overwash and deposition volumes above the shoreline quantitative agreement with the bruun rule and variants of it is found for measured shoreline recession for both barred and bermed beach profiles there is some variability between the profiles at equilibrium at the two different water levels under these idealised conditions deviations between the original bruun rule the modification by rosati et al 2013 and the ptm model predictions are of the order of 15 and all these model predictions are within 30 of the observed shoreline recession measurements of the recession of individual contour responses such as the shoreline may be subject to local profile variability therefore a measure of the mean recession of the profile is also obtained by averaging the recession of discrete contours throughout the active profile the mean recession only requires conservation of volume not conservation of profile shape to be consistent with the bruun rule concept and is found to be in better agreement with all three model predictions than the recession measured at the shoreline

late devensian and holocene relative sea level change in north wales uk deglacial sea level index points defining relative sea level rsl change are critical for testing glacial isostatic adjustment gia model output only a few observations are available from north wales and until recently these provided a poor fit to gia model output for the british irish ice sheet we present results of an integrated offshore geophysical seismic reflection coring drilling rig sedimentological micropalaeontological foraminifera biostratigraphical palynology and geochronological ams 14c investigation into a sequence of multiple peat organic sediment horizons interbedded within a thick estuarine marine sequence of minerogenic clay silts to silty sands from the ne menai strait north wales ten new sea level index points and nine new limiting dates from the devensian late glacial and early holocene are integrated with twelve pre existing holocene sea level index points and one limiting point from north wales to generate a regional rsl record this record is similar to the most recent gia predictions for north wales rsl change supporting either greater ice load and later deglaciation than in the gia predictions generated before 2004 or a modified eustatic function there is no evidence for a mid holocene highstand tidally corrected rsl data indicate initial breaching of the menai strait between 8 8 and 8 4 ka bp to form a tidal causeway with final submergence between 5 8 and 4 6 ka bp final breaching converted the ne menai strait from a flood dominated estuary into a high energy ebb tidal delta with extensive tidal scouring of pre existing late glacial and holocene sequences the study confirms the value of utilising offshore drilling coring technology to recover sea level records which relate to intervals when rates of both eustatic and isostatic change were at their greatest and therefore of most value for constraining gia models copyright 2011 john wiley sons ltd

summary of quaternary stratigraphy and history eastern canada deposits of three wisconsinan substages sangamonian stage and older quaternary stratigraphic units are recognized in eastern canada the age assignment of these units is based on radiocarbon dating and correlation of events quaternary deposits older than sangamonian are recognized locally in eastern canada in southern ontario glacial deposits directly underlie sangamonian sediments and are referred to as illinoian in age in other areas the ages of older sediments are largely unknown offshore core stratigraphy suggests that a major glaciation took place about 436 ka and that the illinoian oxygen isotope stage 6 was also a time of extensive glaciation in this report sangamonian is used as the name for the chronostratigraphic stage that includes all of deep sea oxygen isotope stage 5 and consequently on a regional basis it includes warm interglacial deposits glacial deposits and cool interglacial deposits in southern ontario the warm interglacial deposits are represented by the don formation the stadial deposits by the scarborough formation and the cool interglacial deposits by the pottery road formation warm interglacial deposits have not been recognized in quebec unless they are part of the pre johnville sediments the becancour till is included as glacial sangamonian sediments and the st pierre sediments are recognized as cool interglacial sediments the early wisconsinan appears to have been the time of maximum wisconsinan glaciation in eastern canada with ice moving south of the international boundary and well out onto the continental shelf the middle wisconsinan was primarily a nonglacial period in southern ontario and a glacial stade elsewhere in eastern canada in southern ontario the middle wisconsinan record has been subdivided into two interstades port talbot and plum point separated by a stade cherrytree the port talbot interstade began before the limit of radiocarbon dating before 48 ka and ended about 40 ka glacial or near glacial conditions of the cherrytree stage lasted from about 40 to 35 ka ago and the plum point interstade was from about 35 to 23 ka ago central st lawrence lowland was occupied by ice throughout the middle wisconsinan but southeastern quebec and the montreal area were briefly deglaciated scattered evidence in atlantic canada suggests local deglaciation of coastal areas during middle wisconsinan but extensive ice remained on the continental shelf and ice from centres located on the shelf flowed onto land in at least two areas glacial conditions predominated throughout eastern canada during the late wisconsinan at the late wisconsinan maximum through moving ice deposited the catfish creek drift in southern ontario but ice lobes which developed in the basins of the great lakes after 15 5 ka controlled ice flow during a period of ice margin oscillation and retreat a calving bay developed in lower st lawrence valley after the late wisconsinan maximum causing a reversal of flow on the south shore of the st lawrence and replacing ice in the valley with the champlain sea about 12 ka late wisconsinan glaciers were largely limited to land areas in atlantic canada local ice caps dominated with complicated patterns of flow and retreat developing as centres of accumulation shifted and competing ice centres achieved dominance the period of late wisconsinan retreat in atlantic canada appears to have lasted from about 14 to 10 ka

possible refugia in the alexander archipelago of southeastern alaska during the late wisconsin glaciation the interpretation of the extent of late wisconsin glaciation in southeastern alaska has varied between geologists and biologists maps and reports of the region prepared by geologists commonly indicated that late wisconsin ice extended as a large uniform front west to the edge of the continental shelf however the distribution of plants and animals in the region has led many biologists to suggest that there may have been ice free areas that served as refugia during the late wisconsin based on analyses of aerial photographs topographic maps and bathymetric charts in conjunction with a review of previous literature and reconnaissance fieldwork throughout the region this study presents data supporting a limited ice extent in the alexander archipelago during the late wisconsin and identifies possible ice free areas that may have served as refugia these areas include 1 the fairweather ground 2 the herbert graves island area 3 the western coast of southern baranof island and adjacent continental

stratigraphic relationships and paleoecology of a late glacial peat bed from the queen charlotte islands british columbia the stratigraphic relationships of late glacial and holocene sediments exposed in sea cliffs at cape ball on the queen charlotte islands are summarized based on section descriptions and 13 radioca

palaeoenvironmental interpretation of middle and late wisconsinan fossil coleopteran assemblages from western olympic peninsula washington usa organic sediments exposed in a seacliff near kalaloch washington contain abundant well preserved beetle remains fossil assemblages dating from about 48 000 to 40 000 yr bp are dominated by species typical of the lowland and montane forests in the region today a few species micropeplus laticollis olophrum consimile olophrum boreale arpedium cribratum and tachinus thruppi are presently not members of the pacific northwest fauna mean july temperature during this part of the middle wisconsinan is estimated to have been about 1 c lower than today later wisconsinan assemblages are dominated by non arboreal species indicating a treeless probably tundra environment mean july temperature based mostly on the occurrence of the alpine leaf beetle species asiorestia pallida is estimated to have been at least 3 c lower than the present day palaeoclimatic interpretations based on beetles are in good agreement with those based on pollen

a 14 000 year vegetation history of a hypermaritime island on the outer pacific coast of canada based on fossil pollen spores and conifer stomata abstract pollen and conifer stomata analyses of lake sediments from hippa island on the north coast of british columbia were used to reconstruct the vegetation history of this small hypermaritime island between 14 000 and 13 230 cal yr bp the island supported diverse herb shrub communities dominated by cyperaceae artemisia and salix pinus contorta and picea sitchensis stomata indicate that these conifers were present among the herb shrub communities likely as scattered individuals transition to open p contorta woodland by 13 000 cal yr bp was followed by increases in alnus viridis alnus rubra and p sitchensis after 12 000 cal yr bp pinus dominated communities were replaced by dense p sitchensis and tsuga heterophylla forest with lysichiton americanus and fern understory thuja plicata stomata indicate that this species was present by 8700 cal yr bp but the pollen record suggests that its populations did not expand to dominate regional rainforests along with tsuga and picea until after 6600 cal yr bp conifer stomata indicate that species may be locally present for hundreds to thousands of years before pollen exceed thresholds routinely used to infer local species arrival when combined pollen and conifer stomata can provide a more accurate record of paleovegetation than either when used alone

the lithostratigraphy sedimentology and tectonic setting of the monian supergroup western anglesey north wales the monian supergroup of western anglesey comprises three major lithostratigraphic units the basal south stack group the pelitic new harbour group and the overlying gwna melange the south stack group comprises a sequence of deformed turbiditic metasandstones pelites and subordinate quartzites a dominance of t abcde and t bcde turbiditic units high sandstone to mudstone ratio and the presence of coarsening and thickening upward sequences indicate that the south stack group was deposited in a sand rich fan system the quartzites form large scale sand bodies 10 25 m thick and are interpreted as major channel fill sequences that transported mature quartz arenites from relatively shallow marine environments deeper into the basin by passing the inner to mid fan environments whole rock sedimentary geochemistry indicates that the south stack group was deposited in a continental margin setting the new harbour group forms a monotonous sequence of highly deformed pelites semipelites and subordinate volcaniclastic psammites which exhibit geochemical characteristics of sandstones deposited in a continental island arc setting petrographic data indicate that the new harbour group records the dissection and unroofing of a pre existing andesitic arc complex limited palaeocurrent data obtained for the south stack group and facies changes within the new harbour group suggest that the monian supergroup was deposited within a ne sw trending basin no evidence was found to suggest that the monian supergroup represents part of an accretionary prism consequently the deposition of the monian supergroup within the trench of a monian subduction system cannot be justified

an energetics total load sediment transport model for a plane sloping beach bagnold s energetics based total load sediment transport model for streams is used as a basis for the development of a total load model of time varying sediment transport over a plane sloping bed in both the bedload and suspended load the transport rate vectors are found to be composed of a velocity induced component directed parallel to the instantaneous velocity vector and a gravity induced component directed down slope the model is applied to idealized surfzone conditions leading to estimates of the local longshore and onshore offshore sediment transport rates as well as the equilibrium beach slope as a function of the local wave and current conditions the model is combined with a nonlinear longshore current model and spatially integrated to obtain predictions of the total longshore transport rate as a function of the incident wave conditions the results support the general form of the wave power equation except that the wave power coefficient is no longer constant but is instead a complex function of the incident wave and beach characteristics

a discussion of monian supergroup stratigraphy in northwest wales new borehole data and trench exposures in northern anglesey show the gwna group melange resting directly upon disrupted sedimentary rocks of the new harbour group field evidence from anglesey and the ll n peninsula shows that units previously given formal lithostratigraphic status in the higer part of the monian sopergroup occur as clasts within the gwna group melange me wbdivision of the monian supergroup is therefore simplified to comprise only three groups the south stack lowest new har bour and gwna groups highest the disruption of the upper part of the new harbour group is interpreted to have been efferied during emplacement of the gwna group melange

a wisconsinan interstadial arctic flora and insect fauna from clarksburg southwestern ontario canada abstract radiocarbon dating and sedimentological pollen plant macrofossil and insect analyses were performed on a subtill organic deposit in southwestern ontario canada stratigraphic relationships and minimum radiocarbon dates suggest a middle wisconsinan age the sedimentary sequence indicates a fluvial environment with a rising base level as an approaching ice front dammed and produced a deepening proglacial lake eventually ice covered the site for much of late wisconsinan time the fossil plants and insects indicate an open ground treeless landscape comparable to modern low to high arctic environments in canada the beetle fauna is dominated by members of the sub genus cryobius and is associated with fossils of dwarf shrubs salix herbacea and dryas integrifolia and herbs such as saxifraga oppositifolia

environmental history and tephrostratigraphy at carp lake southwestern columbia basin washington usa sediment cores from carp lake provide a pollen record of the last ca 125 000 years that helps disclose vegetational and climatic conditions from the present day to the previous interglaciation 120 133 ka the core also contained 15 tephra layers which were characterised by electron microprobe analysis of volcanic glass shards identified tephra include mount st helens ye 3 69 ka mazama ash bed 7 54 ka mount st helens layer c 35 50 ka an unnamed mount st helens tephra 75 150 ka the tephra equivalent of layer e at pringle falls oregon 218 ka and an andesitic tephra layer similar to that at tulelake california 174 ka ten calibrated radiocarbon ages and the ages of mount st helens ye mazama ash and the unnamed mount st helens tephra were used to develop an age depth model this model was refined by also incorporating the age of marine oxygen isotope stage is boundary 4 5 73 9 ka and the age of is 5e 125 ka the justification for this age model is based on an analysis of the pollen record and lithologic data the pollen record is divided into 11 assemblage zones that describe alternations between periods of montane conifer forest pine forest and steppe the previous interglacial period is 5e supported temperate xerothermic forests of pine and oak and a northward and westward expansion of steppe and juniper woodland compared to their present occurrence the period from 83 to 117 ka contains intervals of pine forest and parkland alternating with pine spruce forest suggesting shifts from cold humid to cool temperate conditions between 73 and 83 ka a forest of oak hemlock douglas fir and fir was present that has no modern analogue it suggests warm wet summers and cool wet winters cool humid conditions during the mid wisconsin interval supported mixed conifer forest with douglas fir and spruce the glacial interval featured cold dry steppe with an expansion of spruce in the late glacial xerothermic communities prevailed in the early holocene when temperate steppe was widespread and the lake dried intermittently the middle holocene was characterised by ponderosa pine forest and the modern vegetation was established in the last 3900 yr when ponderosa pine douglas fir fir and oak were part of the local vegetation 2000 elsevier science b v all rights reserved

evidence for millennial scale climate change during marine isotope stages 2 and 3 at little lake western oregon u s a pollen and geochemical data from little lake western oregon suggest several patterns of millennial scale environmental change during marine isotope stage mis 2 14 100 27 600 cal yr b p and the latter part of mis 3 27 600 42 500 cal yr b p during mis 3 a series of transitions between warm and cold adapted taxa indicate that temperatures oscillated by ca 2 4 c every 1000 3000 yr highs and lows in summer insolation during mis 3 are generally associated with the warmest and coldest intervals warm periods at little lake correlate with warm sea surface temperatures in the santa barbara basin changes in the strength of the subtropical high and the jet stream may account for synchronous changes at the two sites during mis 2 shifts between mesic and xeric subalpine forests suggest changes in precipitation every 1000 3000 yr increases in tsuga heterophylla pollen at 25 000 and 22 000 cal yr b p imply brief warmings minimum summer insolation and maximum global ice volumes during mis 2 correspond to cold and dry conditions fluctuations in precipitation at little lake do not correlate with changes in the santa barbara basin and may be explained by variations in the strength of the glacial anticyclone and the position of the jet stream c 2001 university of washington

surficial geology of hecate strait british columbia continental shelf four surficial geological units are defined geophysically for hecate strait on the northern british columbia continental shelf they consist of tertiary bedrock unit 1 unconformably overlain in much of the strait of glacial till unit 2 which is in turn overlain below 200 m water depth by thick silts unit 4 and above 200 m by quaternary sands and gravels unit 3 except in areas where till or tertiary bedrock is at or near surface glacial ice covered most of the strait at some time in the pleistocene but evidence for a late wisconsinan advance is more prevalent in the principal troughs of the strait sea level was as low as the present day 180 m isobath during the late tertiary or early quaternary and possibly as low as 100 m at the end of the pleistocene based on the presence of drainage channels wave cut terraces and both shore oblique and shore parallel sand ridges sedimentary bedforms found ubiquitously above 100 m appear to be in equilibrium with the present hydrodynamic conditions and t

shorerise and bar berm profiles on ocean beaches a beach equilibrium model is developed that treats the outer shorerise portion of the profile independently from that of the inner bar berm portion the two portions are matched at the breakpoint bar the partitioning of the profile in this way is consistent with the different forcing modes on either side of the breakpoint this formulation utilizes beach profile data not previously available it is shown that both portions of the profile are well fitted by curves of the form h axm where h is positive downward and x is the positive offshore coordinate surprisingly the value of m 0 4 is nearly the same for shorerise and bar berm and does not change significantly with seasonal beach changes summer winter the principal difference between seasonal profiles is that in winter higher waves the breakpoint bar is deeper and farther offshore while the berm crest is displaced landward thus the changes in seasonal equilibria are manifested by simple self similar displacements of the bar berm and shorerise curves as a consequence of changes in surf zone width and o 1 variations in the factor a

equilibrium beach profiles under breaking and non breaking waves abstract simple theoretical models to determine the equilibrium profile shape under breaking and non breaking waves are presented for the case of breaking waves it is assumed that the seaward transport in the undertow is locally balanced by a net vertical sedimentation so that no bottom changes occur at equilibrium the parameterization of the water and sediment flux in the surf zone yields a power curve for the equilibrium profile with a power of 2 3 which is in agreement with previous field investigations on surf zone profile shapes three different models were developed to derive the profile shape under non breaking waves namely 1 a variational formulation where the wave energy dissipation in the bottom boundary layer is minimized over the part of the profile affected by non breaking waves 2 an integration of a small scale sediment transport formula over a wave period where the slope conditions that yield zero net transport determine equilibrium and 3 a conceptual formulation of mechanisms for onshore and offshore sediment transport where a balance between the mechanisms defines equilibrium conditions all three models produced equilibrium profile shapes of power type with the power typically in the range 0 15 0 30 comparison with field data supported the results obtained indicating different powers for the equilibrium profile shape under breaking and non breaking waves

late pleistocene age size and paleoenvironment of a caribou antler from haida gwaii british columbia the basal portion of a fossil caribou antler from graham island is the only evidence of large terrestrial vertebrates older than the fraser late wisconsin glaciation on haida gwaii this antler h

olympia interstadial vegetation landscape history and paleoclimatic implications of a mid wisconsinan mis3 nonglacial sequence from southwest british columbia canada lithostratigraphic 14c and palynologic analyses of peat and silty peat at three nearby sites reveal a 25 000 year vegetation and climate history of the olympia interstade for the fraser lowland british columbia 300 km within the southern limit of the cordilleran ice sheet at lynn valley polypodiaceae fern spores and nonarboreal pollen dominate 47 8 14c ka bp reflecting unstable and cold landscapes a pinus poaceae zone follows representing pine parkland and cool dry climate fluctuating values of picea and tsuga mertensiana pollen at lynn and seymour valleys and port moody characterize most of the olympia interstade during local peat deposition in cyperaceae and myrica wetlands until about 26 7 14c ka bp under a cool and moist climate a brief pinus tsuga heterophylla zone at lynn valley 44 39 14c ka bp suggests a climatic optimum a poaceae artemisia assemblage and deposition of silty sand after 26 7 14c ka bp reflect cooling and drying after which a unique lycopodium assemblage at lynn valley

late quaternary glaciation and postglacial stratigraphy of the northern pacific margin of canada abstract areas of southeastern alaska and the queen charlotte islands of the northwestern pacific coast of north america were considered to be ice free during the late wisconsinan glaciation and glacial refugia existed however a glacier extended from mainland north america to the shelfbreak in dixon entrance separating alaska and the queen charlotte islands glacial retreat to the east began sometime after 15 000 to 16 000 14 c yr b p and ice had completely left dixon entrance by 13 500 to 13 000 14 c yr b p a rapid sea level regression occurred soon after deglaciation began due to isostatic rebound with relative sea level falling to approximately 150 m below present in central dixon entrance decreasing the size of the inlet by about 30 percent by 12 400 14 c yr b p the late quaternary glacial and postglacial stratigraphic sequence is more than 100 m thick overlying older pleistocene sediments and tertiary bedrock a late wisconsinan diamicton is overlain by glaciomarine muds formed between approximately 14 400 and 13 000 14 c yr b p contemporaneous with the deposition of the glaciomarine muds an extensive outwash deposit formed off the northern coast of the queen charlotte islands to a present depth of 150 m during the sea level lowstand and subsequent transgression a reworked sand unit was deposited over much of the seafloor to depths greater than 450 m the unit is exposed at the seafloor over much of the region suggesting that seabed hydrodynamic energy levels were high after 13 000 14 c yr b p and remain so today

the significance of the boundary between the rhoscolyn and new harbour formations on holy island north wales to the deformation history of anglesey the boundary between the rhoscolyn and new harbour formations on holy island anglesey has been described as a high strain zone or as a thrust the boundary is here described at four localities with reference to the contrasting sedimentary and deformational character of the two formations at one of these localities borth wen sandstones and conglomerates at the top of the rhoscolyn formation are followed without any break by tuffs and then mudstones of the new harbour formation it is concluded that there is clear evidence of depositional continuity across the boundary here and that both formations subsequently shared a common two phase deformation the first d1 was manifestly different in intensity and scale in the two formations whereas the second d2 produced very similar structures in both the other three localities provide continuity of sedimentary and tectonic features at this boundary in a traverse along the length of holy island leading us to identify two previously unrecognized major d1 folds in addition to the rhoscolyn anticline at one of these localities holyhead we confirm the presence of skolithos just below the boundary supporting radiometric evidence for a lower cambrian or later age for the rhoscolyn formation a turbidite interpretation for both the rhoscolyn and new harbour formations best fits the available evidence a deep water depositional environment is still compatible with the sporadic presence of skolithos burrows but less so with reported observations of hummocky and swaley cross stratification lower down the south stack group

holocene vegetation history of the prince william sound region south central alaska abstract vegetation history during the holocene is interpreted from the pollen and sedimentary records of nine sections of peat deposits located in sedge tundra at sites in the northern and northwestern parts of the prince william sound region basal radiocarbon ages of the deposits are between 10 015 and 580 yr b p modern surface pollen data from these and 25 additional sites ranging from lowlands to an altitude of 675 m in the alpine tundra were used to aid in the interpretation of the fossil records both frequency and influx pollen diagrams of the oldest section disclose a sequence of communities beginning with sedge tundra containing thickets of willow and alder followed by alder which became predominant at about 8300 yr b p later alder declined and an inferred growth of sedge tundra and the establishment of colonies of mountain hemlock and sitka spruce with some western hemlock occurred about 2680 yr b p finally regrowth of sedge tundra accompanied by the development of forest communites took place over the past 2000 yr the influence of glacier advances on the vegetation in the fjords occurred during neoglacial episodes dated at 3200 2500 yr b p and during recent centuries regional holocene tectonic activity was also an influential factor especially at the time of the 1964 earthquake

a record of late quaternary vegetation from davis lake southern puget lowland washington abstract pollen and macrofossil analyses of a core spanning 26 000 yr from davis lake reveal late pleistocene and holocene vegetational patterns in the puget lowland the core ranges lithologically from a basal inorganic clay to a detritus gyttja to an upper fibrous peat and includes eight tephra units the late pleistocene pollen sequence records two intervals of tundra parkland vegetation the earlier of these has high percentages of picea gramineae and artemisia pollen and represents the vegetation during the evans creek stade fraser glaciation ca 25 000 17 000 yr b p the later parkland interval is dominated by picea tsuga mertensiana and gramineae it corresponds to the maximum ice advance in the puget lowland during the vashon stade fraser glaciation ca 14 000 yr b p an increase in pinus ontorta pollen between the two tundra parkland intervals suggests a temporary rise in treeline during an unnamed interstade after 13 500 yr b p a mixed woodland of subalpine and lowland conifers grew at davis lake during a period of rapid climatic amelioration in the early holocene the prolonged expansion of pseudotsuga and alnus woodland suggests dry temperate conditions similar to those of present rainshadow sites in the puget lowland more mesic forests of tsuga eterophylla thuja plicata and pseudotsuga similar to present lowland vegetation appeared in the late holocene ca 5500 yr b p

submerged late quaternary terrestrial deposits and paleoenvironment of northern hecate strait british columbia continental shelf canada abstract stratigraphic and paleoenvironmental analyses of sediments recovered from cores on the western canadian continental shelf indicate that areas of the north central shelf were subaerial and supported terrestrial vegetation during the regional late wisconsinan deglaciation paleoecological analyses of now submerged shelf sediments reveal a late quaternary treeless environment locally covered by wet sedge tundra samples from a coeval onshore section on eastern graham island indicate that a dwarf shrub tundra with mosses and willows also occupied lowland areas on the queen charlotte islands between 13 and 14 ka ice free subaerial conditions persisted for a period of at least 3200 years on some parts of the emergent shelf between 13 2 and 10 ka during the same time period clay rich glaciomarine sediment with ice rafted debris was accumulating in the troughs of the shelf low relative sea levels during deglaciation on the continental shelf adjacent to the eastern queen charlotte islands suggest that late wisconsinan ice was thin and limited in extent in this area the presence of a habitable lowland environment during this time interval strengthens the view that a coastal migration of humans from beringia was possible along portions of the exposed continental shelf

late quaternary vegetation and climate history near little lake central coast range oregon pollen and plant macrofossils recovered from little lake oregon provide the first record of late quaternary climate and vegetation changes in oregon9s central coast range the pollen data suggest that the period from ca 42 000 to 24 770 yr b p featured an open forest of western white pine western hemlock and fir the inferred climate was cooler and wetter than today the full glacial period was characterized by a parkland of spruce lodgepole pine and mountain hemlock which suggests that the climate was colder and possibly drier than today the oregon coast range was not a glacial refugium for temperate conifers as has been proposed by 16 000 yr b p the pollen and plant macrofossil data suggest the development of a montane forest composed of pine fir western hemlock and mountain hemlock temperate taxa were present in the vegetation at 13 500 yr b p during a period of climatic amelioration a reversal in this warming trend may have occurred between 11 000 and 10 500 yr b p when pine western and mountain hemlock and spruce were slightly more abundant early holocene forests featured douglas fir red alder and bracken fern implying more severe summer drought and more frequent fires after 5600 yr b p douglas fir western hemlock and western red cedar dominated the record marking the introduction of the present day cool moist climate however during the past 2800 yr increased douglas fir and decreased cedar suggest the possibility of reduced effective moisture at little lake

a glacial readvance during retreat of the cordilleran ice sheet british columbia central coast descriptions of the cordilleran ice sheet retreat after the last glacial maximum have included short lived readvances occurring during the older and younger dryas stadial periods and into the holocene but identification of these events has been largely limited to southwest and central british columbia and northwest washington state we present evidence of a late pleistocene readvance of cordilleran ice occurring on the central coast of british columbia on calvert island between northern vancouver island and haida gwaii evidence is provided by sedimentological and paleoecological information contained in a sedimentary sequence combined with geomorphic mapping of glacial features in the region results indicate that a cold climate existed between 15 1 and 14 3 cal ka bp and that ice advanced to and then retreated from the western edge of the island between 14 2 and 13 8 cal ka bp these data provide the first evidence of a major fluctuation in the retreating ice sheet margin in this region and suggest that a cold climate was a major factor in ice readvance these data contribute to the understanding of past temperature ice loading and crustal response the nature of ice margin retreat and the paleoenvironment of an understudied area of the pacific northwest

airflow and sand transport variations within a backshore parabolic dune plain complex ne graham island british columbia canada onshore aeolian sand transport beyond the beach and foredune is often overlooked in the morphodynamics and sediment budgets of sandy coastal systems this study provides detailed measurements of airflow sand transport via saltation and modified suspension vegetation density and surface elevation changes over an extensive 325 30 m swath of a backshore foredune parabolic dune plain complex near surface 30 cm wind speeds on the backshore ranged from 4 3 to 7 3 m s 1 gusting to 14 0 m s 1 oblique onshore flow is steered alongshore near the incipient foredune then landward into a trough blowout where streamline compression flow acceleration to 1 8 times the incident speed and increasing steadiness occur highest saltation rates occur in steady topographically accelerated flow within the blowout as such the blowout acts as a conduit to channel flow and sand through the foredune into the foredune plain beyond the blowout flow expands vegetation roughness increases and flow decelerates over the foredune plain localized flow steering and acceleration to 1 6 times the incident speed occurs followed by a drop to 40 of incident flow speed in a densely vegetated zone upwind of an active parabolic dune at 250 m from the foredune sediment properties reflect variations in near surface flow and transport processes well sorted fine skewed backshore sands become more poorly sorted and coarse skewed in the blowout due to winnowing of fines sorting improves and sands become fine skewed over the foredune plain toward the parabolic dune due to grainfall of finer sands winnowed from the beach and foredune during the fall winter season significant amounts of sand up to 110 kg m 2 are transported via modified suspension and deposited as grainfall up to 300 m landward of the foredune no distinct trend in grainfall was found although most fell on the depositional lobe of the blowout and at 200 m near an isolated active parabolic dune grainfall amounts may reflect several transporting events over the measurement period and the transport process is likely via localized modified suspension from the crest of the foredune and other compound dune features in the foredune plain this evidence suggests that the process of grainfall delivery though often overlooked in coastal research may be a key process in maintaining active dunes hundreds of metres from the shoreline in a densely vegetated foredune plain the effectiveness of this process is controlled by seasonal changes in vegetation cover and wind strength as well as shorter term e g tidally controlled variations in sand availability from the beach

geology and paleoecology of a middle wisconsin fossil occurrence in zorra township southwestern ontario canada nonglacial deposits of middle wisconsin age are being discovered with increased frequency across a broad region of southern ontario canada and provide strong evidence for a time of significant ice withdrawal from the lower great lakes region with each new discovery a refined understanding of regional climatic and paleoecological environments is emerging in this paper we present the results of a sedimentological and paleoecological study of a subtill organic deposit in zorra township southwestern ontario the organic deposit which lies beneath nissouri phase catfish creek till late wisconsin has been dated by accelerator mass spectrometry at between 50 5 and 42 9 14c ka bp the organic remains are contained within slack water pond deposits infilling a channel incised into till either of early wisconsin or illinoian age the fossil assemblage appears to be strongly influenced by taphonomic processes including degradation due to oxidation bacterial and fungal decay and glacial overriding rewor

equilibrium shoreface profiles a sediment transport approach abstract large scale coastal behaviour models use the shoreface profile of equilibrium as a fundamental morphological unit that is translated in space to simulate coastal response to for example sea level oscillations and variability in sediment supply despite a longstanding focus on the shoreface profile and its relevance to predicting coastal response to changing environmental conditions the processes and dynamics involved in shoreface equilibrium are still not fully understood here we apply a process based empirical sediment transport model combined with morphodynamic principles to provide new insight into equilibrium shoreface profile development and shape the quantitative model is based on field measurements and shows that a balance between onshore sediment transport due to oscillatory wave motion and offshore sediment transport due to gravity produces profile shapes that are similar to natural shoreface profiles from the danish north sea coast and the southeast australian coast model predictions of equilibrium profile response to the effects of climate change such as rising sea level or changing wave climates are examined implementation of the model is straightforward there is no tuning or calibration and computation times are short it is therefore easily implemented with repeated iterations to manage uncertainty

post glacial sea level change along the pacific coast of north america abstract sea level history since the last glacial maximum on the pacific margin of north america is complex and heterogeneous owing to regional differences in crustal deformation neotectonics changes in global ocean volumes eustasy and the depression and rebound of the earth s crust in response to ice sheets on land isostasy at the last glacial maximum the cordilleran ice sheet depressed the crust over which it formed and created a raised forebulge along peripheral areas offshore this combined with different tectonic settings along the coast resulted in divergent relative sea level responses during the holocene for example sea level was up to 200 m higher than present in the lower fraser valley region of southwest british columbia due largely to isostatic depression at the same time sea level was 150 m lower than present in haida gwaii on the northern coast of british columbia due to the combined effects of the forebulge raising the land and lower eustatic sea level a forebulge also developed in parts of southeast alaska resulting in post glacial sea levels at least 122 m lower than present and possibly as low as 165 m on the coasts of washington and oregon as well as south central alaska neotectonics and eustasy seem to have played larger roles than isostatic adjustments in controlling relative sea level changes

stratigraphy and paleoecology of pleistocene interstadial sediments central british columbia abstract two exposures of organic rich interstadial sediments in central british columbia provide information on middle wisconsinan environments and climates near the center of the region subsequently covered by the late wisconsinan cordilleran ice sheet interstadial sediments at bullion pit overlie drift of early wisconsinan or older age and underlie thick drift of late wisconsinan age alluvium or colluvium and peat were deposited on the floor of the ancestral quesnel river valley 46 000 40 000 14 c yr ago when the vegetation consisted of spruce forest with dry openings and local fens and the climate was colder and perhaps drier than today this is broadly consistent with paleoclimatic reconstructions for the same time interval for babine lake 400 km to the northwest and for meadow creek 400 km to the southeast plant rich pond sediments containing tephra layers and vertebrate remains are exposed between two drifts in a ravine at mexican hill 30 km east of quesnel although they may be contemporaneous with the bullion pit beds the nonglacial sediments at mexican hill more likely were deposited sometime after the warmest part of the last interglaciation but prior to 50 000 yr b p at that time the vegetation at mexican hill probably was parkland the present vegetation at mexican hill is boreal forest thus a drier and possibly cooler climate is indicated

paleoecology and ice limits of the early fraser glaciation marine isotope stage 2 on haida gwaii british columbia canada

postglacial vegetation and climate dynamics in the seymour belize inlet complex central coastal british columbia canada palynological evidence from tiny lake a pollen based study from tiny lake in the seymour belize inlet complex of central coastal british columbia canada permits an evaluation of the dynamic response of coastal temperate rainforests to postglacial climate change open pinus parklands grew at the site during the early lateglacial when the climate was cool and dry but more humid conditions in the later phases of the lateglacial permitted mesophytic conifers to colonise the region early holocene conditions were warmer than present and a successional mosaic oftsugaheterophylla andalnus occurred at tiny lake climate cooling and moistening at 8740 70 14 c a bp initiated the development of closed late successional t heterophylla cupressaceae forests which achieved modern character after 6860 50 14 c a bp when a temperate and very wet climate became established the onset of early holocene climate cooling and moistening at tiny lake may have preceded change at more southern locations including within the seymour belize inlet complex on a meso to synoptic scale this would suggest that an early holocene intensification of the aleutian low pressure system was an important influence on forest dynamics in the seymour belize inlet complex and that the study region was located near the southern extent of immediate influence of this semi permanent air mass copyright 2008 john wiley sons ltd

extent and timing of the last glacial maximum in southwestern alaska a glacier complex composed of confluent alpine glaciers island ice caps and piedmont lobes covered much of the alaska peninsula and kodiak island during the last glacial maximum lgm because this glacier complex formed the southeastern border of beringia its dynamics may have been important in the timing and feasibility of the northwest coast route for human migration into lower latitude north america radiocarbon dates from stratigraphic sections on kodiak island and in the bristol bay lowlands bracket the lgm in southwestern alaska between 23 000 and 14 700 yr b p reconstruction of ice thickness based on glacier trimlines moraines and calculations of basal shear stress depict the alaska peninsula glacier complex flowing to the outer edge of the continental shelf in the gulf of alaska equilibrium line altitudes elas were 300 to 700 m lower than today and approached sea level on the southwestern alaska peninsula in northeastern areas where elas were higher bedrock topography largely controlled ice flow except where ice saddles bridged straits and inlets

late quaternary geology of eastern graham island queen charlotte islands british columbia a reconnaissance study of quaternary sediments exposed in coastal bluffs on eastern graham island has revealed the presence of two major till units each of which is underlain by glaciomarine stony mud outwash sand and gravel and laminated to massive silt and sand of undetermined origin sediment units below the surface drift are older than the radiocarbon dating limit sediments above this drift provide a nearly continuous record of geologic events from before 16 000 years bp until the present stratigraphic evidence and radiocarbon dates indicate that 1 late wisconsin glaciation of the coastal lowlands of graham island was weak and of short duration and 2 a period of low sea levels during late pleistocene time was followed by a transgression that culminated about 7500 8000 years ago when the sea was about 15 m higher relative to the land than at present marine regression during middle and late holocene time produced wave cut scarps wave cut benches overlain by littoral sediments bars spits and beach and dune ridges

geology and paleoecology of a mid wisconsin peat from the queen charlotte islands british columbia canada abstract a peat bed on east central graham island of the queen charlotte islands occurs within a nonglacial fluvial succession that is both overlain and underlain by glacial deposits radiocarbon dates of 27 500 400 and 45 700 970 yr b p at the top and base of the peat respectively indicate that it was deposited during the mid wisconsin nonglacial interval the peat is the first documented mid wisconsin organic deposit in northern coastal areas of british columbia three local pollen zones are represented the lowest zone pm 1 is restricted to sandy silt directly underlying the dated peat very high cyperaceae and moderate poaceae pollen percentages characterize zone pm 1 and a variety of other herbs are common suggesting an open landscape rather than a forested one the middle zone pm 2 is characterized by abundant pollen of picea tsuga mertensiana and cyperaceae and also contains pollen of abies a genus now absent from the queen charlotte islands graham island probably had extensive forests at this time but abundant pollen and macrofossils of cyperaceae and emergent aquatics such as hippuris vulgaris veronica scutellata potentilla palustris and menyanthes trifoliata indicate that there also were open wetland areas zone pm 3 also contains abundant arboreal pollen large amounts of sphagnum spores and selaginella selaginoides megaspores indicate succession of the wetland area at the sample site to a peat bog paleoecological analysis of the data suggests that subalpine vegetation elements were depressed by at least 400 m probably due to a cooler climate probable modern analogs in southeastern alaska and the presence of abies probably a amabilis indicate that precipitation was higher on eastern graham island during the mid wisconsin than at present

volcanic sequence and alteration at the parys mountain volcanic hosted massive sulfide deposit wales united kingdom applications of immobile element lithogeochemistry lenses of massive zn pb cu sulfides at the parys mountain deposit in anglesey northwestern wales occur at and near the contact between ordovician shales and overlying rhyolites the rhyolites which have been dated as lower silurian parrish 1999 have a thickness of a few hundred meters and are overlain by lower silurian shales the rhyolites and shales strike northeasterly for 2 to 3 km and dip to the north minor basalts are present but there are no intermediate rocks cu bearing stockwork veins occur in the upper portion of the ordovician shales and cu bearing mineralization was mined from the lower silurian shales in the 18th century precambrian basement rocks are present to the south and north of parys mountain application of immobile element lithogeochemical techniques to 1 000 drill core and outcrop samples allows division of the rhyolites into five main chemical types a b c d1 and d2 the shales into three main types and the mafic rocks into two types the distribution of these units has been mapped across the property where individual volcanic chemical units have lateral continuity they are considered to represent singular geologic events and thus are time markers correlations based on volcanic facies alone are of limited use because a chemical unit can pass laterally through different volcanic facies whereas in strongly altered zones the original volcanic facies cannot be recognized at all the chemostratigraphic units on the other hand can be traced through even the most altered zones consequently they provide an improved means of correlating volcanic units on local to property scales the first volcanic rocks to accumulate above the ordovician shales were thin flows and volcaniclastic beds of rhyolite b and a laterally adjacent lens of largely massive rhyolite c the main massive sulfide lenses in the western part of the property are associated with these volcanic events these units were covered by thick flows of rhyolite a in the western part of the property rhyolites d and a are the main chemical types in the eastern part rhyolite d has two subtypes d1 is generally massive and flow banded whereas d2 is pyroclastic it is suggested that rhyolite d1 was erupted first followed by less fractionated rhyolite d2 which was the last volcanic event prior to the accumulation of the silurian shales the main vents for rhyolite a in the west and d in the east were separated by about 1 km the alteration minerals at parys mountain are sericite chlorite quartz pyrite and fe bearing carbonates mass changes calculated for the rhyolites and the shales show a general property scale increase in alteration in the downdip direction feo and mgo additions of up to 10 and 20 wt percent respectively are present in footwall shales up to 50 m below the massive sulfide lenses in areas where stockwork veins are present similar feo and mgo gains occur in rhyolites up to 50 m above the ore lenses in rhyolites with fe mg gains si and k have generally been lost in areas lateral to the massive sulfides shales and rhyolite b have gained large amounts of silica most parys mountain rhyolites have moderately high nb contents and slightly inclined rare earth element ree patterns whereas the basalts are enriched in the high field strength elements hfse including the light ree the primary geochemical features of the volcanic rocks together with regional geologic relationships in northwestern wales suggest that volcanism occurred during intraplate rifting of a small marine basin which was underlain by precambrian continental crust the small volumes of all rhyolite types and basalt at parys mountain suggest that they were derived from small discrete pods of magma which were tapped by basement faults most of the massive sulfides accumulated immediately before and during the first outpourings of rhyolitic lava