timing and extent of early marine oxygen isotope stage 2 alpine glaciation in skagit valley washington twenty two new radiocarbon ages from skagit valley provide a detailed chronology of alpine glaciation during the evans creek stade of the fraser glaciation early marine oxygen isotope stage mis 2 in the cascade range washington state sediments at sites near concrete washington record two advances of the baker valley glacier between ca 30 3 and 19 5 cal ka bp with an intervening period of glacier recession about 24 9 cal ka bp the baker valley glacier dammed lower skagit valley creating glacial lake concrete which discharged around the ice dam along finney creek or south into the sauk valley sediments along the shores of ross lake in upper skagit valley accumulated in glacial lake skymo after ca 28 7 cal ka bp behind a glacier flowing out of big beaver valley horizontally laminated silt and bedded sand and gravel up to 20 m thick record as much as 8000 yr of deposition in these glacially dammed lakes the data indicate that alpine glaciers in skagit valley were far less extensive than previously thought alpine glaciers remained in advanced positions for much of the evans creek stade which may have ended as early as 20 8 cal ka bp

the vegetation and climate history of the last glacial cycle in a new pollen record from lake fimon southern alpine foreland n italy abstract the sediments of lake fimon n italy contain the first continuous archive of the late pleistocene environmental and climate history of the southern alpine foreland we present here the detailed palynological record of the interval between termination ii and the last glacial maximum the age depth model is obtained by radiocarbon dating in the uppermost part of the record downward we correlated major forest expansion and contraction events to isotopic events in the greenland ice core records via a stepping stone approach involving intermediate correlation to isotopic events dated by tims u th in alpine and apennine stalagmites and to pollen records from marine cores of the iberian margin modelled ages obtained by bayesian analysis of deposition are thoroughly consistent with actual ages with maximum offset of 1700 years sharp expansion of broad leaved temperate forest and of sudden water table rise mark the onset of the last interglacial after a treeless steppe phase at the end of penultimate glaciation this event is actually a two step process which matches the two step rise observed in the isotopic record of the nearby antro del corchia stalagmite respectively dated to 132 5 2 5 and 129 1 5 ka at the interglacial decline mixed oak forests were replaced by oceanic mixed forests the latter persisting further for 7 ka till the end of the eemian succession warm temperate woody species are still abundant at the eemian end corroborating a steep gradient between central europe and the alpine divide at the inception of the last glacial after a stadial phase marked by moderate forest decline a new expansion of warm broad leaved forests interrupted by minor events and followed by mixed oceanic forests can be identified with the north alpine saint germain i the spread of beech during the oceanic phase is a valuable circumalpine marker the subsequent stadial interstadial succession lacking the telocratic oceanic phase is also consistent with the evidence at the north alpine foreland the middle wurmian full glacial is marked by persistence of mixed forests dominated by conifers but with significant lime and other broad leaved species a major arboreal pollen decrease is observed at modelled age of 38 7 0 5 ka larch expansion and last occurrence of lime which has been related to heinrich event 4 the evidence of afforestation persisting south of the alps throughout most of mis 3 contrasts with a boreal and continental landscape known for the northern alpine foreland pointing to a sharp rainfall boundary at the alpine divide and to southern air circulation this is in agreement with the alpine paleoglaciological record and is supported by the pressure and rainfall patterns designed by mesoscale paleoclimate simulations strenghtening the continental high pressure during the full glacial triggered cyclogenesis in the middle latitude eastern europe and orographic rainfall in the eastern alps and the balkanic mountains thus allowing forests development at current sea level altitudes

uranium series ages of travertines and timing of the last glaciation in the northern yellowstone area wyoming montana uranium series age determinations by mass spectrometric methods were done for travertines and associated carbonate veins related to clastic deposits of the last glaciation pinedale in the northern yellowstone area dramatic variations in the hydrologic head are inferred from variations in the elevation of travertine deposition with time and are consistent with the expected hydrologic effects of glaciation we determine the following chronology of the pinedale glaciation with the key assumption that travertine deposits and associated carbonate veins perched high above present thermal springs were deposited when glaciers filled the valley below these perched deposits 1 the early pinedale outlet glacier advanced well downvalley between 47 000 and 34 000 yr b p 2 the outlet glacier receded to an interstadial position between 34 000 and 30 000 yr b p 3 an extensive pinedale ice advance occurred between 30 000 and 22 500 yr b p 4 a major recession occurred between 22 500 and 19 500 yr b p 5 a minor readvance deckard flats culminated after 19 500 yr b p and 6 recession from the deckard flats position was completed before 15 500 yr b p this chronology is consistent with the general trend of climatic changes in the northern hemisphere as revealed by recent high resolution ice core records from the greenland ice sheet

lake devlin and pinedale glacial history front range colorado abstract glacial lake devlin was an ice margin lake that formed during pinedale time when the north boulder creek valley glacier blocked the mouth of a tributary near the downvalley limit of glaciation the lake was about 2 km long and as much as 60 m deep and was fed by meltwater from small valley glaciers it accumulated sediment apparently without interruption for about 10 000 yr the inception of lake devlin between 23 500 and 21 000 yr b p provides a limiting date for the maximum expansion of pinedale ice because the lake could not form until the north boulder creek glacier had advanced to within 2 km of its downvalley limit the maximum lowering of timberline which occurred about 19 000 yr b p is assumed to coincide with the pinedale glacial maximum apparent timberline elevations determined from picea pinus pollen ratios suggest that ice front positions during the time between 23 000 and 19 000 yr b p may have been only slightly less extensive than at the pinedale maximum lake devlin drained catastrophically about 13 000 yr b p which was after ice had receded from the outlet area pinedale glaciation in the front range began about or after 30 000 yr b p and final deglaciation occurred between 15 000 and 12 000 yr b p

early deglaciation in the tropical andes the record of ancient glaciers is the principal source of information on high altitude paleoclimate in the tropics but the age of late pleistocene glaciation throughout the tropics is poorly constrained which complicates estimating past climate from glacial records seltzer et al 1 1

multi scale curvature for automated identification of glaciated mountain landscapes erosion by glacial and fluvial processes shapes mountain landscapes in a long recognized and characteristic way upland valleys incised by fluvial processes typically have a v shaped cross section with uniform and moderately steep slopes whereas glacial valleys tend to have a u shaped profile with a changing slope gradient we present a novel regional approach to automatically differentiate between fluvial and glacial mountain landscapes based on the relation of multi scale curvature and drainage area sample catchments are delineated and multiple moving window sizes are used to calculate per cell curvature over a variety of scales ranging from the vicinity of the flow path at the valley bottom to catchment sections fully including valley sides single scale curvature can take similar values for glaciated and non glaciated catchments but a comparison of multi scale curvature leads to different results according to the typical cross sectional shapes to adapt these differences for automated classification of mountain landscapes into areas with v and u shaped valleys curvature values are correlated with drainage area and a new and simple morphometric parameter the difference of minimum curvature dmc is developed at three study sites in the western united states the dmc thresholds determined from catchment analysis are used to automatically identify 5 5 km quadrats of glaciated and non glaciated landscapes and the distinctions are validated by field based geological and geomorphological maps our results demonstrate that dmc is a good predictor of glacial imprint allowing automated delineation of glacially and fluvially incised mountain landscapes

extensive mountain glaciation in central patagonia during marine isotope stage 5 abstract the timing and magnitude of glacial advances throughout a glacial cycle can give insight on the underlying drivers of climate change our knowledge of glacial activity early in a glacial cycle however is limited by incomplete preservation of the geomorphological record here we present a b 10 e dated glacial chronology from early in the last glacial cycle from the belgrano valley east of monte san lorenzo in central patagonia our chronology reveals the most extensive glacial advance of the last glacial cycle occurred at 75 ka at the end of marine isotope stage 5 a second less extensive advance occurred at 25 ka during the global last glacial maximum the topographic setting is such that ice growth would have initiated on and around the san lorenzo massif at the start of the glacial cycle we suggest reduced southern hemisphere summer insolation at the time played a significant role in driving this early advance the comparatively smaller glacier extent during the global last glacial maximum is likely a consequence of the build up of the full patagonian ice sheet which would have caused ice divide migration ice flow re routing and increased aridity on its lee side

varied climatic and topographic influences on late pleistocene mountain glaciation in the western united states the timing of late pleistocene mountain glacier fluctuations varied widely across the western united states glaciers in the maritime olympic mountains reached local maxima 125 60 ka and 34 31 ka and were far less extensive during the global last glacial maximum lgm glaciers in the cascade mountains showed a similar general pattern but with contrasts in detailed timing most mountain glacier systems further inland exhibited maximum ice extent during marine isotope stage mis 2 in the wallowa wind river and possibly the sawtooth mountains maximum ice extent occurred ca 20 23 ka mountain glacier systems of the cordilleran ice sheet puget lobe greater yellowstone region and uinta mountains reached maximum extent ca 19 16 ka and those in the wallowa sawtooth and wind river ranges were at near maximum positions ca 17 ka the variable timing of maximum and near maximum ice advances appears to be related to climatic setting and glacier mass balance characteristics mountain glacier systems under the strongest maritime influences reached maximum extent at times of strong westerly atmospheric flow olympic and cascades glaciers appear to have been negatively influenced by weakened westerly flow at the time of the global lgm perhaps associated with ice sheet induced anticyclonic flow glacier systems with maximum advances correlative with the global lgm appear to have responded more strongly to depressed temperature the ca 17 ka ice advances of several glacier systems are broadly correlative with heinrich event 1 in the north atlantic region and imply a cooling event and reinvigoration of moisture transport into the region post lgm advances of uinta mountain glaciers appear to have arisen from moisture influences of pluvial lake bonneville copyright 2008 john wiley sons ltd

evaluation of pores under different management systems by image analysis of clay soils in saskatchewan canada abstract the influence of tillage operations on soil porosity is not yet completely understood and requires further attention image analysis was used to evaluate the impact of deep ripping and paraplowing on soil porosity in two lacustrine soils in saskatchewan large undisturbed soil samples 25 50 15 cm were collected after harvest and dried by the acetone immersion technique to avoid shrinkage four thin sections of 11 8 cm were prepared from each sample and video images were acquired from the thin sections using a contron ibas image analysis system total porosity 50 m of the soils from the control parcels was high and appeared to be adequate for normal crop growth increased amounts of clay likely increase the percent of soil porosity by a natural swell shrink process deep ripping increased the porosity of soils in the surface horizon whereas the influence of paraplowing was evident at 30 to 60 cm depth the increase occurred as pores with a shape factor sf 2mm thus the two tillage methods used in this study caused an increase in large planar voids in general tillage has little influence on non planar voids sf 0 2 as they occur in the aggregates and they are not destroyed by cultivation despite the increase in porosity at the lucky lake site by deep tillage no increase could be found in crop production in this region suggesting that this tillage operation is not needed in the dry chernozemic soil considering their dynamics pores should be measured more frequently and over a long time so that a clearer picture could be obtained for better management of soils

chronology of pleistocene glacial advances in the central rocky mountains the distribution and ages of moraines in the wyoming type localities for pre pinedale rocky mountain glacial deposits are not well known through morphostratigraphic mapping river terrace longitudinal profile analysis and tephrochronology we place the age of sacagawea ridge moraines in the dinwoody lakes type area at about 660 ka outwash and river terrace deposits in the bull lake type area previously considered to be sacagawea ridge are actually older by one or two glacial cycles in the bull lake type locality 15 individual moraines are divided into 4 groups on the basis of relative age criteria using 36cl 10be cosmogenic dating of boulders the two older groups must be 130 ka the younger groups are given age ranges of 130 to 100 ka and 120 to 95 ka a terrace along wind river can be morphostratigraphically traced to the youngest of these moraine groups 36cl dating of boulders on the terrace provides an age range of 125 to 100 ka the combined relative age and cosmogenic nuclide chronology is consistent with previously published evidence from yellowstone national park demonstrating that mountain glaciers advanced not only prior to and during the later portion of marine isotope stage 6 but also during marine isotope stage 5d in contrast with some other areas of the rocky mountains we found no evidence for advances during marine isotope stage 4 at bull lake pinedale moraines that have a 36cl 10be age range of 23 to 16 ka suggest that glacial advances were limited to the later part of marine isotope stage 2 a river terrace that can be traced to these moraines has an age range of 23 to 16 ka a possible glacial advance during early marine isotope stage 2 is indicated by a river terrace whose age range is estimated by incision rate modeling at 46 to 28 ka but no moraines were identified along wind river there are eight terrace levels capped with outwash that are older than sacagawea ridge although the terraces are the record of early to middle pleistocene climatic cycles there are no correlative moraines preserved at the land surface

a loess paleosol record of climate and glacial history over the past two glacial interglacial cycles 150 ka southern jackson hole wyoming abstract loess accumulated on a bull lake outwash terrace of marine oxygen isotope stage 6 mis 6 age in southern jackson hole wyoming the 9 m section displays eight intervals of loess deposition loess 1 to loess 8 oldest each followed by soil development our age depth model is constrained by thermoluminescence meteoric 10 be accumulation in soils and cosmogenic 10 be surface exposure ages we use particle size geochemical mineral magnetic and clay mineralogical data to interpret loess sources and pedogenesis deposition of mis 6 loess was followed by a tripartite soil thin loess complex soils 8 7 and 6 apparently reflecting the large climatic oscillations of mis 5 soil 8 mis 5e shows the strongest development loess 5 accumulated during a glacial interval 76 69 ka mis 4 followed by soil development under conditions wetter and probably colder than present deposition of thick loess 3 43 51 ka mis 3 was followed by soil development comparable with that observed in soil 1 loess 1 mis 2 accumulated during the pinedale glaciation and was followed by development of soil 1 under a semiarid climate this record of alternating loess deposition and soil development is compatible with the history of yellowstone vegetation and the glacial flour record from the sierra nevada

latest pleistocene glacial chronology of the uinta mountains support for moisture driven asynchrony of the last deglaciation abstract recent estimates of the timing of the last glaciation in the southern and western uinta mountains of northeastern utah suggest that the start of ice retreat and the climate driven regression of pluvial lake bonneville both occurred at approximately 16 cal ka to further explore the possible climatic relationship of uinta mountain glaciers and the lake and to add to the glacial chronology of the rocky mountains we assembled a range wide chronology of latest pleistocene terminal moraines based on seventy four cosmogenic 10be surface exposure ages from seven glacial valleys new cosmogenic exposure ages from moraines in three northern and eastern valleys of the uinta mountains indicate that glaciers in these parts of the range began retreating at 22 20 ka whereas previously reported cosmogenic exposure ages from four southern and western valleys indicate that ice retreat began there between 18 and 16 5 ka this spatial asynchrony in the start of the last deglaciation was accompanied by a 400 m east to west decline in glacier equilibrium line altitudes across the uinta mountains when considered together these two lines of evidence support the hypothesis that lake bonneville influenced the mass balance of glaciers in southern and western valleys of the range but had a lesser impact on glaciers located farther east regional scale variability in the timing of latest pleistocene deglaciation in the rocky mountains may also reflect changing precipitation patterns thereby highlighting the importance of precipitation controls on the mass balance of pleistocene mountain glaciers

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

the legacy of past urban waste disposal on local soils many attributes of present day soils can only be explained by reference to land management in the historic past this is particularly well expressed in the plaggen soils which occur extensively on the north european plain these deepened soils owe their dominant characteristics to the application from the 12th century of turf materials often impregnated with dung similar deepening of soils can result from the disposal of urban waste this paper discusses the results of soil research focused on a small scottish town nairn a soil survey revealed topsoils of over 1 m overlying fluvioglacial sands and gravels such deepening is explained by the use of town waste on the burgh s arable lands from at least the 17th century up until the mid 19th century when an integrated sewerage system was installed micromorphological study of this deepened topsoil revealed the presence of many small black carbonaceous particles oxygen carbon ratios were calculated from microprobe results as a means of confirming the carbonaceous nature of these particles soil phosphorus was primarily concentrated on the perimeter of these particles the high quality of present day soils on the edge of the town is explained by the disposal of waste material which included much carbonised material this paper is the first to highlight the importance and potential of examining the gradation in soils from urban to rural contexts

cosmogenic 10be and 36cl ages from late pleistocene terminal moraine complexes in the taylor river drainage basin central colorado usa abstract cosmogenic surface exposure ages from boulders on a terminal moraine complex establish the timing of the local last glacial maximum lgm in the taylor river drainage basin central colorado five zero erosion 10 be ages have a mean of 19 5 1 8 ka while that for three 36 cl ages is 20 7 2 3 ka corrections for modest rates 1 mm ka 1 of boulder surface erosion result in individual and mean ages that are generally within 2 of their zero erosion values both the means and the range in ages of individual boulders are consistent with those reported for late pleistocene moraines elsewhere in the southern and middle rocky mountains and thus suggest local lgm glacier activity was regionally synchronous two anomalously young zero erosion 10 be ages mean 14 4 0 8 ka from a second terminal moraine are tentatively attributed to the boulders having been melted out during a late phase of ice stagnation

an archaeopedological and phytolitarian study of the dark earth on the site of rue de dinant brussels belgium during the excavations of the site of rue de dinant in the historic centre of brussels belgium remains of the first city wall dating from the 13th century have been discovered intra muros thick dark sediment units predating this wall are observed these dark units are among the oldest occupation traces so far encountered in this higher eastern part of the historic centre of brussels in order to characterise them and to understand the human activities and natural processes behind their formation an interdisciplinary research integrating archaeopedology and phytolith study has been undertaken this approach permitted us to identify a range of natural and cultural processes leading to the formation of these dark layers and to characterise different activities remains of a hearth old plough land cropfields and grassland have been identified all activities referring to a rural landscape organisation later on the area changes into an enormous silt extraction area whereby dark earth is thrown into the dug pits finally the construction of the first city wall marks the area as becoming part of the city the study of dark earth shows to be a potentially valuable tool to shed light on the development and spatial organisation of pre urban brussels a historically very poorly documented period

structural interpretation of the midcontinent rift in eastern lake superior from seismic reflection and potential field studies integrated interpretations of potential field and glimpce and industry seismic reflection data in eastern lake superior reveal the structural and stratigraphic complexity of the midcontinent rift in this region projection of the keweenaw fault into southeastern lake superior suggested by early potential field studies is confirmed by seismic reflection data analysis of seismic data in conjunction with aeromagnetic anomalies and regional gravity data also reveals a continuous section of basalt in the footwall of the keweenaw fault the lateral dimensions of this section vary along the strike of the rift from the center of the basin towards the southern flank spatially extensive anticlinal and synclinal features reverse faults and related drag folds imaged by the reflection and enhanced potential field data attest to the influence of a late stage compressional event in this region east northeast trending gradients and displacements associated with observed potential field anomalies and fault traces mapp

millennial scale deep water oscillations reflections of the north atlantic in the deep pacific from 10 to 60 ka northeast pacific benthic foraminiferal 18o and 13 reveal repeated millennial scale events of strong deep sea ventilation associated with nutrient depletion and or high gas exchange during stadial cool high ice volume episodes from 10 to 60 ka opposite the pattern in the deep north atlantic two climate mechanisms may explain this pattern north pacific surface waters chilled by atmospheric transmission from a cold north atlantic and made saltier by reduced freshwater vapor transports could have ventilated the deep pacific from above alternatively faster turnover of pacific bottom and mid depth waters driven by southern ocean winds may have compensated for suppressed north atlantic deep water production during stadial intervals during the younger dryas event 11 6 13 0 cal ka ventilation of the deep ne pacific 2700 m lagged that in the santa barbara basin 450 m by 500 years suggesting that the ne pacific was first ventilated at intermediate depth from above and then at greater depth from below this apparent lag may reflect the adjustment time of global thermohaline circulation

an application of spectral image analysis to soil micromorphology 2 comparison of two soil profiles abstract pedological features in undisturbed samples from similar depths in two brookston clay loam soil orthic humic gleysol or typic haplaquoll profiles were compared one in the never cultivated state nc and the other under long term 30 years continuous corn zea mays l cc colour digital images of polished section samples from the nc ah2 bg and ckg and the cc ap bkg and ckg horizons were produced with an eikonix scanner and analyzed with an easi pace spectral image analysis system the spectral intensity values of delineated features were grouped into classes to produce maps of their spatial distribution image areal percentages for the features were measured void space feature results were compared with previous point counting and single channel image analyses quantitative and visual results for features indicated that the soil compaction associated with the cc cropping practice gave the ap horizon properties that more closely resembled those of the deeper b and c horizons than those of the nc ah2 horizon these properties included 1 a reduced macroporosity 50 2 organic material dispersed throughout the peds light coloured and concentrated only along the macropores dark coloured and 3 weakly developed gleysolic characteristics faint mottles in the interior regions of the peds 27 of sample area

patterns and causes of millennial scale climate change in the pacific northwest during marine isotope stages 2 and 3 abstract a high resolution pollen record from fargher lake washington shows a series of millennial scale changes in vegetation and climate during marine isotope stages mis 3 and 2 a comparison of fargher lake with pollen records from little lake oregon and carp lake washington reveals regional patterns of change during the early part of mis 3 ca 60 000 45 000 cal yr bp fargher and carp lakes indicate transitions between open and closed vegetation and cold dry and warm wet conditions between 45 000 and 27 500 cal yr bp all three records show shifts between low and high elevation taxa that indicate a series of temperature changes these temperature changes are similar to those in the santa barbara basin and may be explained by changes in the strength of the aleutian low during mis 2 27 500 14 000 cal yr bp shifts between wet and dry adapted taxa were most prominent at little lake there is also evidence for two minor warmings mis 2 climate variations do not correlate well with those in the santa barbara basin however precipitation changes in the pacific northwest during mis 2 correlate with evidence of ice sheet surges into the north atlantic and were probably related to variations in the strength and position of the glacial anticyclone and the jet stream

deciphering topographic signals of glaciation and rock uplift in an active orogen a case study from the olympic mountains usa estimating recent patterns of erosion and rock uplift within cenozoic orogens has proven difficult as signals of these processes have been obfuscated by plio pleistocene glaciation the topography of many mountain ranges integrates the effects of long lived rock uplift late cenozoic climate variation and post glacial landscape adjustment in this study we employ a suite of topographic analyses to study the relief of an active mountain range on a sub catchment scale in an effort to the separate the long term signal of rock uplift from perturbations due to shorter lived climate signals we focus on the olympic mountains usa where patterns of exhumation and glaciation have been previously estimated however our methods and results are broadly applicable to other orogens our analysis shows that plio pleistocene alpine glaciers and the cordilleran ice sheet have reduced the elevations of channel profiles and created anomalously low channel relief in the olympic mountains large low gradient areas formed at lower elevations where ice sheets were present and alpine glaciers widened and deepened valleys in the more rugged core of the range near threshold hillslopes along the margins of the oversteepened glacially carved valleys dominate the range this implies a strong plio pleistocene glacial climate control on the topography over the more recent evolution of the olympic mountains however the broad relief structure of the range appears to still record the regional rock uplift pattern and is suggestive of an east plunging antiform consistent with folding of the subducting plate or underplating of accreted rocks copyright 2017 john wiley sons ltd

timing of glaciation during the last glacial cycle evaluating the concept of a global last glacial maximum lgm abstract it has long been known that mountain glaciers and continental ice sheets around the globe reached their respective maximum extent at different times during the last glacial cycle often well before the global last glacial maximum lgm c 23 19 ka which is formally defined by peaks in global sea level and marine oxygen isotope records however there is increasing evidence from around the world that it was not only mountain glaciers which were asynchronous with the global lgm but also some regions of the large continental glaciers the barents kara ice sheet in northern eurasia together with a majority of ice masses throughout asia and australasia reached their maximum early in the last glacial cycle a few thousand years before the global lgm period the east antarctic ice sheet also reached its maximum extent several millennia before the global lgm in numerous mountainous regions at high mid and low latitudes across the world glaciers reached their maximum extent before marine isotope stage mis 2 in mis 5 4 and 3 this is in contrast to most sectors of the laurentide ice sheet the cordilleran ice sheet the se sector of the fennoscandinavian ice sheet and the alpine ice sheet in central europe which appear to have reached their maximum close to the global lgm in mis 2 the diachronous maximum extents of both mountain glaciers and continental ice sheets during the last glacial cycle means that the term and acronym last glacial maximum lgm has limited chronostratigraphical meaning when correlating glacial deposits and landforms

a fluvial record of long term steady state uplift and erosion across the cascadia forearc high western washington state six late quaternary river terraces preserved along the clearwater river in northwestern washington state provide a 140 ka record of long term incision and uplift across the western side of the cascadia forearc high terrace ages are constrained by weathering rind and radiocarbon dating and by correlation to dated coastal glacio fluvial deposits and the global eustatic curve the terraces overlie flat bedrock surfaces called straths which represent uplifted segments of the river channel bedrock incision is measured by the height of a strath relative to the adjacent modern river channel the straths along the clearwater show an upstream increase in bedrock incision ranging from 0 at the coast to a maximum of 110 m in the headwaters the incision at any point along the profile increases systematically with strath age the calculated incision rates range from 10 ky the clearwater river valley has maintained a steady state profile defined by a long term balance in the rates of incision and rock uplift upstream divergence of terraces is best explained by an increase in the rate of rock uplift from the coast toward the central part of the range these results are consistent with other evidence indicating a long term steady state balance between the accretionary influx and the erosional outflux for this part of the cascadia subduction wedge since 14 ma these results help show how terrace deposits form in tectonically active landscapes the dominantly fluvial clearwater drainage was forming straths while alpine glaciers were advancing in adjacent drainages in turn the straths were buried during the transition to interglacial times because of increased sediment supply due to local deglaciation and because of eustatic highstands that forced aggradation in the lower reach of the drainage and across the continental shelf as well the fluvial system shows strong forcing by the glacial climate cycle even so the river appears to have returned to the same valley profile during each cycle of strath cutting thus bedrock incision is clearly unsteady at time scales shorter than the glacial climate cycle 100 ky but appears to be relatively steady when averaged over longer time scales a simple kinematic model is used to examine how uplift of the cl our analysis indicates that the accretionary flux into the wedge occurs mainly by frontal accretion and not by underplating if accretion occurred entirely at the front of the wedge the present west coast should be moving to the northeast at 3 m ky relative to a fixed puget sound this prediction is in good agreement with offset of a 122 ka sea cliff preserved at the southwest side of the clearwater valley profile in this case the long term margin perpendicular shortening would account for 20 to 35 percent of the geodetically measured northeast southwest shortening across the olympic mountains

relict soils and early arable land management in lofoten norway relict arable soils dating fromc ad700 provide an opportunity to identify early arable land management practices in the agriculturally marginal landscapes of the lofoten archipelago northern norway synthesis of field survey and soil thin section micromorphology supported by image analysis suggests that there was deliberate management of erodible sandy soils in sloping locations to create small areas of cultivation terrace with a range of materials used as soil amendments to stabilize the accumulated soil and enhance fertility small areas of sandy soils in more gently sloping locations were also cultivated again with a range of materials used as amendments and which contributed to a significant increase in soil thickness the last phase of cultivation commenced during the late 1800s and involved the reclamation of wetter peaty soils by spade these patterns of arable land management are repeated in different parts of lofoten and indicate that despite the climatic and economic marginality of arable activity in lofoten land management practices were developed and applied to permit barley production from small areas

semiannual variation in the western tropical pacific ocean 1 analysis of altimeter data combined with results from a high resolution general circulation model has revealed the existence of a semiannual variation in the western tropical pacific the semiannual variation cannot be explained by local ekman pumping alone but is also related to the westward propagation of rossby waves originating in the central tropical pacific corresponding in the northern hemisphere with the inter tropical convergence zone and in the southern hemisphere with the south pacific convergence zone this signal intensifies toward the western boundary and appears to have a notable impact on the circulation there in the mindanao current the semiannual variation is of comparable strength with the annual variation this finding is supported by a moored acoustic doppler current profile measurement during the period from october 1999 to july 2002

glider observations of the north equatorial current in the western tropical pacific the north equatorial current nec of the pacific ocean advects subtropical subpolar and tropical water masses repeat underwater glider observations of the nec from june 2009 to january 2014 along 134 3 e provide absolute zonal geostrophic velocity transport and water mass structure at length scales of 10 1000 km the nec is strongest near the surface and persistent eastward undercurrents are identified deeper than potential density surface 26 kg m 3 at 9 6 n and 13 1 n mean transport from the surface to 27 3 kg m 3 and 8 5 n 16 5 n is 37 6 sv 106 m3 s 1 with a standard deviation of 15 6 sv the transport variability is greatest deeper than 26 kg m 3 due to undercurrent variability wavelet analysis at scales of 10 80 km reveals extrema of fine scale salinity variance along isopycnals spice variance high spice variance is found in the north pacific tropical water nptw and the north pacific intermediate water npiw with a spice variance minimum between water masses at 25 5 kg m 3 a horizontal cox number ch relates salinity variance at fine scales 10 80 km to that at greater length scales 120 200 km as a function of density ch is nearly vertically uniform indicating that the stirring of mean salinity gradients enhances fine scale salinity variance nptw with an estimated horizontal eddy diffusivity of order 104 m s 2 is a useful tracer for the region and may be used to relate the fine scale salinity variance to an eddy diffusivity

development of a novel image analysis procedure to quantify biological porosity and illuvial clay in large soil thin sections among other driving forces climate change may lead to significant modifications of soil properties through variations of the intensity and dynamics of a number of soil processes including the especially sensitive and ubiquitous processes of bioturbation and illuviation progress toward the quantification of these processes needs to be made as a first step in order to ascertain or predict the impact of climate change in this study we develop and validate through an exhaustive accuracy assessment a digital 2d image analysis method adapted to large soil thin sections leading to the quantification characterization and classification of pores and illuvial clay features considered diagnostic of bioturbation and illuviation respectively the need to consider large soil thin sections 14 x 6 cm stems from observations that areas from 684 mm2 to more than 5 000 mm2 are needed to obtain representative measurements of fragments of illuvial clay papules and porosity associated with earthworms respectively whereas the soil heterogeneity in thin sections of such a large size prohibits the use of classical global and colorimetric image analysis procedures we succeeded to quantify and characterize the porosity and illuvial clay features with accuracies as high as 96 for porosity and 92 for illuvial clay by carefully considering different levels of soil organization from aggregates to individual illuvial clay features quantification of the size and the shape of pores and of illuvial clay features makes it possible to develop morphological classifications distinguishing pores of biological origin earthworms or roots from others or clay coatings and infillings from papules all these data are particularly useful to better characterize underlying soil processes results suggest that the proposed methodology provides an accurate and representative quantification of biological porosity and illuvial clay features in large thin sections we argue that the use of this approach could be extended to study and quantify bioturbation and illuviation intensities at the profile scale

a 4000 year record of hydrologic variability from the olympic mountains washington usa sedimentological and geochemical analyses of gravity and piston cores retrieved from lake quinault washington reveal an 4000 year flood dominated depositional record individual flood event laye

correlation of late pleistocene glaciation in the western united states with north atlantic heinrich events a survey of the chronology of late pleistocene glaciers in the western united states indicates a record of glacier advances during the last glaciation which is more variable than that predicted by orbital forcing numerical dating of late pleistocene deposits from the puget lobe of the cordilleran ice sheet and alpine glaciers and ice caps in the rocky mountains and cascade range suggests that advances and retreats of these glaciers were in phase with episodes of growth and collapse of the laurentide ice sheet associated with the north atlantic heinrich events specifically the existing chronologies indicate that these glaciers were advancing to their terminal areas up to several thousand years before a heinrich event and retreated shortly thereafter because midlatitude glaciers respond relatively rapidly to climate change this complex record of glacial fluctuations suggests mechanisms of climate forcing in western north america that are in some way tied to heinrich events one possible mechanism involves southerly and northerly displacement of the jet stream across the western united states in response to growth and collapse of the laurentide ice sheet

early anthropogenic soil formation at tofts ness sanday orkney abstract a buried dark coloured loam soil horizon embedded between calcareous wind blown sand deposits is identified in three areas of the tofts ness landscape the close association with early settlement sites and enhanced total phosophate levels suggests that this soil horizon is anthropogenic in origin radiocarbon dating and stratigraphic relationships with settlement sites indicate that the horizon is associated with bronze age cultural landscape activity and may have commenced formation during the late neolithic period horizon formation is interpreted through a synthesis of thin section micromorphology stable carbon isotope analysis and analysis of free soil lipids these analytical methods indicate that formation was through the application of grassy turf material together with domestic waste midden while cultivation was moderately intense as evidenced by the movement of fine material through the horizon the closest parallels to these soil horizons are the cultural plaggen soils of continental north west europe with the tofts ness soils amongst the earliest known of these soil types application of this manuring technique at tofts ness allowed arable activity in what was a highly marginal farming environment emerging evidence from other parts of the northern isles of scotland suggests that these manuring strategies were commonly used in early arable systems

the formation of deep topsoils in orkney the soil survey for scotland in their mapping of the soils in orkney identified a deep top phase of the bilbster series this soil is distinguished by having a topsoil usually in excess of 75 cm and it occurs almost exclusively on the mainland of orkney especially in the west round marwick and skaill bays an anthropogenic origin to this soil is proposed and the present study is designed to investigate the particular processes of formation which have led to the increase in soil depth results from transect and grid surveys indicate how the soil is thickest adjacent to old farms the historical literature suggests a wide range of possible inputs from seaweed and calcareous sand to turves after they had been used as bedding for cattle analytical results support the last process as the dominant one and an accumulation rate of c 1 mm yr is proposed

the deglaciation of the americas during the last glacial termination this paper reviews current understanding of deglaciation in north central and south america from the last glacial maximum to the beginning of the holocene together with paleoclimatic and paleoceanographic data we compare and contrast the pace of deglaciation and the response of glaciers to major climate events during the global last glacial maximum glgm 26 5 19 ka average temperatures decreased 4 to 8 c in the americas but precipitation varied strongly throughout this large region many glaciers in north and central america achieved their maximum extent during the glgm whereas others advanced even farther during the subsequent heinrich stadial 1 hs 1 glaciers in the andes also expanded during the glgm but that advance was not the largest except on tierra del fuego hs 1 17 5 14 6 ka was a time of general glacier thickening and advance throughout most of north and central america and in the tropical andes however glaciers in the temperate and subpolar andes thinned and retreated during this period during the bolling allerod interstadial b a 14 6 12 9 ka glaciers retreated throughout north and central america and in some cases completely disappeared many glaciers advanced during the antarctic cold reversal acr 14 6 12 9 ka in the tropical andes and patagonia there were small advances of glaciers in north america central america and in northern

orbital forcing of mid latitude southern hemisphere glaciation since 100 ka inferred from cosmogenic nuclide ages of moraine boulders from the cascade plateau southwest new zealand cosmogenic nuclide be 10 exposure dating of moraine boulders in the cascade valley southwest new zealand reveals three phases of glaciation with similar maximum magnitude since 100 ka in this area 8 10 lateral moraines were deposited during the last glacial maximum lgm at 22 19 ka and 15 lateral moraines and three end moraines were deposited during recession after the lgm also three exposure ages of 29 33 ka from pre lgm deposits may indicate increased weathering and erosion at the onset of the lgm in new zealand as has been suggested by other studies an exposure age of 57 8 2 7 ka from one of the highest moraines combined with previous studies of cave speleothems glacial features offset by the alpine fault the vostok dust record and sediment cores supports the inference that a significant glacial phase culminated at 66 58 ka a cluster of five exposure ages from older moraines reveals a glacial phase with at least three advance retreat cycles at 79 0 3 9 ka correlation between the ages of glacial periods and the timing of southern hemisphere summer insolation minima suggests that orbital forcing has played a first order role in regulating glacial extent in new zealand

climate and tectonic controls on glaciated critical taper orogens abstract in this work we present the results of a new analytical model that examines the coupling between glacial erosion and orogen development surface processes are assumed to be glacially dominated and tectonic activity is controlled by critical wedge mechanics in these circumstances we find that orogen width is strongly dependent on both the rate of accretion and on the rate of precipitation the orogen size is linked to tectonic and climate changes via proportionality constants the orogen width scales with the rate of accretion to between the 2 3rd and 2nd powers and with the rate of precipitation to the 1 3rd and 5 4th powers the value of the proportionality constants varies with the taper angle and the relative rates of ice deformation and sliding in all cases the sensitivities are higher than those calculated for fluvially eroding critical wedge orogens analytical solutions are supported by the results of a numerical flow line model the flow line model further predicts that uplift rates will be highest at and just below the equilibrium line altitude if glacial ablation is largely a calving process rock uplift in the wedge will be strongly focused towards the toe the predicted response time of glaciated orogens to changes in climate and tectonic forcing is dependent upon the constants of erosion the rheology and the rate of precipitation these analyses predict that actual orogens have variable e folding response times for example approximately 1 5 myr for the southern alps of new zealand and the olympic mountains of washington state and approximately 5 5 myr for the european alps

palynology and micromorphology of a man made soil a reconstruction of the agricultural history since late medieval times of the posteles in the netherlands summary man made soils plaggen soils are soils which for centuries were fertilized with a mixture of manure and sods litter and sand pollen analysis of a section from a man made soil revealed a record of successive vegetations and cultivated plants comparable with the results of pollen analysis of an adjacent peat developed near a source of a vanished brooklet the introduction of fagopyrum about 1450 a d and the application of commercial fertilizers about 1900 a d deliver two fixed levels in the soil and peat profiles the average rate of peat growth and the average rate of the accumulation of the plaggen soil material can be calculated in this way the base of the plaggen soil is dated about 1350 a d through micromorphological study it is clear that a part of the plaggen material originates from the flood plain of the surrounding riverlets and that a great part of the humification took place in the stable the manure heap and finally in the plough layer in the field the major part of the pollen influx comes directly from the crops on the field and only a minor part is derived by air from the surrounding areas the pollen is preserved mainly in fecal pellets which is demonstrated by the zonation in the pollen diagram

coupling glacial erosion and tectonics at active orogens a numerical modeling study 1 climate change indirectly alters the distribution of tectonic uplift at active orogens by modifying the action of surface processes which in turn alters mountain topography the impact of alpine glaciation on tectonic activity is explored here the predictions of previous analytical critical wedge models are compared with the output of a numerical model that explicitly couples rock uplift produced by convergence with surface erosion glacial and fluvial and erosive processes are calculated over a two dimensional grid which uses an ice evolution model to calculate the rate of glacial erosion due to ice sliding tectonic uplift is determined by a two dimensional finite element convergence model the simulations performed support the predictions of previous one dimensional analytical modeling of fluvially dominated orogens increasing precipitation decreases orogen width by the one quarter power the simulations show that glacially dominated landscapes have similar dependencies the total glacial erosion yield is determined to be proportional to the glacial coverage sublinearly dependent on the precipitation rate and linearly dependent on the glacial erosion constant that relates erosion with sliding speed climate also determines the distribution of tectonic uplift in the model if the equilibrium line altitude ela is high and glacial processes are limited to peak regions the center of the mountain range experiences the highest rate of rock uplift extensive glaciation increases rock uplift rates on the flanks of the range the style of glacial erosion is also important a simple glacial buzzsaw does not create the same tectonic response as models that physically simulate glacial erosion the simulations support the idea that a climate cooling of the magnitude recorded in the late cenozoic has the potential to more than double the rate of rock uplift in appropriate orogens the implications of the model are discussed for observations from the olympic mountains of washington state the southern alps of new zealand the alaskan coastal range and the southern andes

cosmogenic 36cl and 10be ages of quaternary glacial and fluvial deposits of the wind river range wyoming we measured cosmogenic 36 cl in 56 samples from boulders on moraines and fluvial terraces in the vicinity of the wind river range wyoming we also measured 10 be in 10 of the same samples most of the 10 be ages were in good agreement with the 36 cl ages indicating that rock surface erosion rates were very low the oldest moraine investigated the type sacagewea ridge site yielded only a limiting minimum age of 232 ka the oldest moraines in the type bull lake complex also could be constrained only to 130 ka the main sequence of type bull lake moraines yielded age distributions indicating deposition within the intervals 130 to 100 ka and 120 to 100 ka the best estimates are closer to the upper limits of these ranges and associated uncertainties are in the range of 10 to 15 these uncertainties could permit deposition in either marine isotope stage 6 or stage 5d we found no evidence of glacial deposits dating to marine isotope stage 4 both bull lake age moraines from fremont lake on the opposite side of the wind river range and boulders on a fluvial terrace above the wind river gave age distributions very similar to that of the second oldest bull lake advance ca 130 to 100 ka the distribution of boulder ages for pinedale moraines at bull lake indicated deposition between 23 and 16 ka nearly identical to the distribution of 10 be ages previously reported for the type pinedale moraines at fremont lake

precipitation landsliding and erosion across the olympic mountains washington state usa abstract in the olympic mountains of washington state landsliding is the primary surface process by which bedrock and hillslope regolith are delivered to river networks however the relative importance of large earthquakes versus high magnitude precipitation events to the total volume of landslide material transported to valley bottoms remains unknown in part due to the absence of large historical earthquakes to test the hypothesis that erosion is linked to precipitation approximately 1000 landslides were mapped from google earth imagery between 1990 and 2015 along a 15 km wide 85 km long 1250 km2 swath across the range the volume of hillslope material moved by each slide was calculated using previously published area volume scaling relationships and the spatial distribution of landslide volume was compared to mean annual precipitation data acquired from the prism climate group for the period 1981 2010 statistical analysis reveals a significant correlation r 0 55 p

living with sand a record of landscape change and storminess during the bronze and iron ages orkney scotland abstract palaeoenvironmental analyses of an exposed sequence of interbedded sand and peat overlying glacial till on stronsay orkney has revealed evidence of dynamic landscape change during the holocene ams radiocarbon and osl dating are used to identify periods of minerogenic and organic sediment accumulation a lengthy period of stability during the early holocene is inferred from the development of a deeply weathered till surface with pollen and soil micromorphological evidence suggesting prolonged woodland cover during the mid to late holocene phases of wind blown sand that inundated the landscape are defined from the sedimentary record and are interpreted as periods of increased storminess between c 3400 3100 cal bp and c 2800 2260 cal bp the palaeoecological evidence points to continuity of human exploitation despite the phases of increased storminess during the bronze age and into the iron age rising sea levels and a severe storm event at c 650 years bp inundated the site with massive sands and truncated the record these storm events recorded on stronsay are part of a regionally synchronous record for periods of increased storminess across the north atlantic region during the holocene

variable responses of western u s glaciers during the last deglaciation cosmogenic 10 be exposure ages from moraines in the wallowa mountains oregon identify two maximal late pleistocene glaciations at 21 1 6 0 4 ka and 17 0 6 0 3 ka and a minor glacial event at 10 2 6 0 6 ka our new high resolution chronology integrated with other well dated glacial records from the western united states demonstrates sub stantial differences in the synoptic responses of western u s glaciers to climate forcing associated with the global last glacial maximum and subsequent millennial scale events originating in the north atlantic region these variable synoptic glacier responses identify large changes in the relative contributions of regional to global controls on the climate of the western united states that accompanied the deglaciation

asynchronous maximum advances of mountain and continental glaciers the last maximum glacier advance in many mountain ranges appears to have predated the last maximum advance of the wisconsinan continental ice sheets 20 000 years b p published evidence from widely spaced localities in north and south america europe asia and hawai i suggests that some mountain glaciers extended farther during one or more stades early in the last glaciation roughly 115 000 30 000 years b p than at its end when low global temperature and high precipitation presumably were most favorable for the growth of glaciers variations in the timing of glacier advances in different mountain ranges suggest that alpine glaciers are dependent on regional climate as well as global conditions their study might provide sensitive tests for theories of global climate change glacial deposits are often used as time markers in neotectonic and geomorphic studies and their ages sometimes are inferred from distant measurements or from proxy histories of global climate change undated geomorphic features such as moraines sharply incised streams and river terraces which commonly have been associated with the last maximum glacier advance 20 000 years b p or last deglaciation 13 000 years b p may actually be older by a factor of 2 to 4 or more conversely deposits assigned to the maximum advances of the penultimate global glaciation 130 000 years b p may actually date from early in the most recent glacial cycle and be younger by a comparable factor rates of faulting or folding estimated from displacements or deformation and the assumed ages of such geomorphic features might be too great or too small by corresponding factors

subthermocline eddies in the western equatorial pacific as shown by an eddy resolving ogcm abstractsporadic in situ observations have shown evidence that subthermocline eddies exist off the mindanao coast these subthermocline eddies are believed to play an important role in the heat freshwater and other ocean property transports of the region but their characteristics and in particular their pathway and source of energy are poorly explored because of the lack of long term observations analysis of results from an eddy resolving general ocean circulation model has revealed that most subthermocline eddies off the mindanao coast originate from the equatorial south pacific ocean to the west of the ninigo group these eddies propagate northward along the new guinea coast cross the equator in the far western pacific and reach the mindanao coast at a typical propagation speed of 0 12 m s 1 the dominant time scales of these eddies range between 50 and 60 days

latest pleistocene alpine glacier advances in the sawtooth mountains idaho usa reflections of midlatitude moisture transport at the close of the last glaciation mountain glaciers in the sawtooth mountains responded strongly to reinvigorated atmospheric moisture transport following the last ice sheet maximum the glaciers constructed an extensive moraine belt in the southeastern sawtooth mountains allowing determination of a detailed radiocarbon chronology from lake and marsh cores moraine morphometry and soil data indicate construction of seven to nine moraines in each of four valleys during two main late pleistocene ice advances a basal radiocarbon date from marsh cores in the alturas valley documents that the maximum advance during marine oxygen isotope stage 2 occurred shortly before ca 16 900 calibrated cal yr b p minimum limiting dates on glacial lacustrine sediment in lake and marsh cores from three valleys clustered around 13 950 cal yr b p document the maintenance or reestablishment of extensive ice volume during early late glacial time the ca 16 900 cal yr b p advance postdates the last ice sheet maximum by 4000 yr and is broadly correlative with maximum advances of the north yellowstone outlet glacier and the puget lobe of the cordilleran ice sheet and a near maximum advance of wallowa mountain glaciers these synchronous advances indicate response of a variety of ice systems to reinvigorated moisture transport following the ice sheet maximum as does the subsequent sawtooth advance during early late glacial time together these responses indicate strong sensitivity of certain ice systems to moisture delivery fluctuations

late holocene land use at orstad jaeren southwestern norway evidence from pollen analysis and soil micromorphology abstract pollen analysis was combined with radiocarbon dating physical chemical and biological soil analyses and soil micromorphology to investigate the prehistoric land use at orstad in jaeren southwestern norway orstad is an early bronze age clearance cairn field in a cultural landscape with traces of land use back to the neolithic samples were mainly collected from an 84 m long excavated trench with mainly podzolic soils although pollen preservation was poor it was possible to differentiate five phases in the local vegetation and land use history human impact on the site could be traces back to about 4400 4000 bp uncal 3045 2600 cal bc wheat and barley have been cultivated at orstad during a period from ca 3600 bp uncal 1945 1750 cal bc until the older iron age when heather vegetation began to spread on the site soil micromorphology revealed different soil management practices for this time period the soils seem to have been cleared by fire prior to cultivation until ca 3200 bp uncal 1610 1455 cal bc then new cultivation fields were laid out on higher levels and seem to have been improved by adding of organic materials mainly turves taken from podzolic top soils and peats from nearby localities

luminescence dating of late pleistocene proximal glacial sediments in the olympic mountains washington abstract late pleistocene glacial sediments from the south fork hoh river valley in the olympic mountains washington usa were dated using optically stimulated luminescence osl on quartz sand high sediment supply typical of glacial environments short transport distances and sediment newly eroded from bedrock sources were expected to pose problems for luminescence dating samples were collected from five distinct sedimentary facies using approximated distances from the ice front to assess how luminescence results varied due to these factors and to determine which samples produced the most reliable age estimates results from the south fork hoh highlight the importance of transport environment and sedimentary facies on solar resetting sediments from better sorted ice distal environments were determined to be more completely bleached and more reliable for osl dating samples were collected as part of larger research goals to improve understanding of the glacial history of the south fork hoh river valley

extensive early and middle wisconsin glaciation on the western olympic peninsula washington and the variability of pacific moisture delivery to the northwestern united states abstract large glaciers descended western valleys of the olympic mountains six times during the last wisconsin glaciation terminating in the pacific coastal lowlands the glaciers constructed extensive landforms and thick stratigraphic sequences which commonly contain wood and other organic detritus the organic material coupled with stratigraphic data provides a detailed radiocarbon chronology of late pleistocene ice margin fluctuations the early wisconsin lyman rapids advance which terminated prior to ca 54 000 14c yr b p represented the most extensive ice cover subsequent glacier expansions included the hoh oxbow 1 advance which commenced between ca 42 000 and 35 000 14c yr b p the hoh oxbow 2 advance ca 30 800 to 26 300 14c yr b p the hoh oxbow 3 advance ca 22 000 19 300 14c yr b p the twin creeks 1 advance 19 100 18 300 14c yr b p and the subsequent undated twin creeks 2 advance the hoh oxbow 2 advance represents the greatest ice extent of the last 50 000 yr with the glacier extending 22 km further downvalley than during the twin creeks 1 advance which is correlative with the global last glacial maximum local pollen data indicate intensified summer cooling during successive stadial events because ice extent was diminished during colder stadial events precipitation not summer temperature influenced the magnitude of glaciation most strongly regional aridity independently documented by extensive pollen evidence limited ice extent during the last glacial maximum the timing of glacier advances suggests causal links with north atlantic bond cycles and heinrich events

beryllium 10 dating of the duration and retreat of the last pinedale glacial sequence accurate terrestrial glacial chronologies are needed for comparison with the marine record to establish the dynamics of global climate change during transitions from glacial to interglacial regimes cosmogenic beryllium 10 measurements in the wind river range indicate that the last glacial maximum marine oxygen isotope stage 2 was achieved there by 21 700 700 beryllium 10 years and lasted 5900 years ages of a sequence of recessional moraines and striated bedrock surfaces show that the initial deglaciation was rapid and that the entire glacial system retreated 33 kilometers to the cirque basin by 12 100 500 beryllium 10 years

radiocarbon age constraints on rates of advance and retreat of the puget lobe of the cordilleran ice sheet during the last glaciation abstract calibrated radiocarbon dates of organic matter below and above till of the last fraser glaciation provide limiting ages that constrain the chronology and duration of the last advance retreat cycle of the puget lobe in the central and southeastern puget lowland seven dates for wood near the top of a thick proglacial delta have a weighted mean age of 17 420 90 cal yr b p which is the closest limiting age for arrival of the glacier near the latitude of seattle a time distance curve constructed along a flowline extending south from southwestern british columbia to the central puget lowland implies an average glacier advance rate of ca 135 m yr the glacier terminus reached its southernmost limit ca 16 950 yr ago and likely remained there for ca 100 yr in the vicinity of seattle where the glacier reached a maximum thickness of 1000 m ice covered the landscape for ca 1020 yr postglacial dates constraining the timing of ice retreat in the central lowland are as old as 16 420 cal yr b p and show that the terminus had retreated to the northern limit of the lowland within three to four centuries after the glacial maximum the average rate of retreat was about twice the rate of advance and was enhanced by rapid calving recession along flowline sectors where the glacier front crossed deep proglacial lakes

textural pedofeatures and pre hadrian s wall ploughed paleosols at stanwix carlisle cumbria u k abstract during the last 30 years the value of sandy silty or dusty textural pedofeatures for identifying past agricultural practices has been the subject of debate particularly with regard to the applicability of modern analogue observations to ancient soils macro and micromorphological analyses were carried out on all the contexts in a series of five trenches containing pre roman plough grooves in moderately sandy buried soil profiles at sites near hadrian s wall cumbria micromorphological observations of 31 thin sections showed that the pedofeatures in question were not preferentially distributed in thin sections of sediments from within or below the plough layers but were more concentrated in contexts which as shown by field and archaeological evidence were unlikely to have been affected by cultivation conversely the pedofeatures were absent in other thin sections of sediments from and below the contexts where past agriculture was documented by field and archaeological features the analysis also showed that the pedofeatures in question tended to be distributed in parts of the sequence with suitable porosity soil structure and texture rather than in relation to the position of the cultivated layers all the results in this case study showed that silty sandy and dusty pedofeatures were not diagnostic for past agricultural practices and highlighted the need for more research on the micromorphological evidence of ancient soils with a known record of past agriculture

younger dryas environments and human adaptations on the west coast of the united states and baja california on the pacific coast of the united states and baja california the younger dryas was one component of dynamic late pleistocene and holocene environmental changes changing climate sea level rise and shifting shorelines created ecological challenges for ancient coastal peoples and daunting challenges for archaeologists searching for early coastal sites this paper reviews the evidence for ecological change in this west coast region including shoreline changes that may have submerged or destroyed archaeological sites from this time period examining the regional record of human occupation dating to the younger dryas well dated coastal sites are limited to california s northern channel islands and isla cedros off baja california a small number of fluted points found in coastal areas may also date to the younger dryas but their context and chronology is not well defined review of the implications of these two data sets considers whether the early but discontinuous younger dryas archaeological record from the west coast might result from a migration of maritime peoples from northeast asia into the americas

mindanao dome variability over the last 160 kyr episodic glacial cooling of the west pacific warm pool we present sea surface upper thermocline and benthic delta 18 o data as well as temperature and paleoproductivity proxy data from the international marine global change study program images core md06 3067 6 degrees 31 n 126 degrees 30 e 1575 m water depth located in the western equatorial pacific ocean within the flow path of the mindanao current our records reveal considerable glacial interglacial and suborbital variability in the mindanao dome upwelling over the last 160 kyr dome activity generally intensified during glacial intervals resulting in cooler thermocline waters whereas it substantially declined during interglacials in particular in the early holocene and early marine oxygen isotope stage mis 5e when upwelling waters did not reach the thermocline during mis 3 and mis 2 enhanced surface productivity together with remarkably low sst and low upper ocean thermal contrast provide evidence for episodic glacial upwelling to the surface whereas transient surface warming marks periodic collapses of the mindanao dome upwelling during heinrich events we attribute the high variability during mis 3 and mis 2 to changes in the el nino southern oscillation state that affected boreal winter monsoonal winds and upper ocean circulation glacial upwelling intensified when a strong cyclonic gyre became established whereas el nino like conditions during heinrich events tended to suppress the cyclonic circulation reducing ekman transport thus our findings demonstrate that variations in the mindanao dome upwelling are closely linked to the position and intensity of the tropical convection and also reflect far field influences from the high latitudes

humptulips revisited a revised interpretation of quaternary vegetation and climate of western washington usa abstract new pollen data from a 770 cm core of a mire at humptulips on the southwestern olympic peninsula 47 17 00 n 123 54 40 w and from a nearby deposit regarded as interglacial in age on the west fork of the humptulips river provide evidence for a reinterpretation of previous accounts of the quaternary vegetation and climate using a new age model the highly variable record at humptulips is here correlated with marine oxygen isotope stages ois 1 5a vegetation during ois 5a was pine dominated mixed woodland and tundra in ois 4 3 and 2 oscillations in pollen assemblages imply repeated intervals of mountain hemlock parkland and tundra pine as an indicator of openness is also abundant in these stages interstadial fluctuations in ois 3 reflect episodes of lowland western hemlock communities the earliest of the episodes is of infinite radiocarbon age and the latest dates to approximately 30 000 14 c yr b p parkland in ois 2 occurring after 24 600 until at least 18 440 14 c yr b p was replaced by transitional pine alder in ois 1 holocene which unlike any of the earlier stages conveys the development of modern lowland forest dominated by western hemlock pollen assemblages over the length of record imply that temperature and humidity at no time were as high as at present only in ois 3 do conditions approach those occurring in ois 1 during ois 2 3 and 4 when tree line apparently stood at the location of the site climate was colder and drier temperatures were depressed an estimated 5 c with precipitation close to 1000 mm compared with 2000 3000 mm at present atmospheric circulation during ois 2 appears to have been much controlled by the location of the laurentide ice sheet in the continental interior whereas under the current climatic regime beginning in the early holocene westerly air flow has dominated regulated by interplay between the north pacific high in summer and the wintertime aleutian low

late pleistocene and early holocene environmental history of southwestern washington state u s a a comparison of pollen records and associated plant remains from sites along a major precipitation gradient in southwestern washington enables reconstruction of the late quaternary environment during glacial and early holocene time during the evans creek stade 25 000 17 000 years bp little moisture reached lowlands east of the olympic mountains and as a result both the puget trough and the columbia basin featured a cold dry climate and parkland tundra vegetation in glacial time greatest aridity seems to have occurred between 19 000 and 17 000 years bp after 17 000 years bp the development of mesophytic subalpine parkland suggests that maritime conditions extended farther east into the puget trough and the cascade range became an important precipitation divide conditions warmer and or drier than today developed throughout western washington between 10 000 and 8000 6000 years bp vegetation on opposite sides of the cascade range became dissimilar as early as 17 000 years bp but this trend was ac

epeirogenic controls on canadian river incision and landscape evolution great plains of northeastern new mexico abstract the canadian river has carved a deep bedrock canyon into the great plains of northeastern new mexico in response to a complex interaction of post laramide epeirogenic rock uplift processes along the jemez lineament and downstream baselevel fall caused by late tertiary and quaternary evaporite dissolution broad slow bulging along the jemez lineament a lithospheric scale structure with prolific late cenozoic volcanism along its trend helps drive incision in the canyon canadian river canyon fluvial terraces mapped and correlated according to soils elevation and rock type criteria reveal longitudinal profiles that appear broadly warped across the jemez lineament and converge to the modern channel profile both upstream and downstream of the canyon similarly the modern channel long profile is distinctly and broadly convex through its great plains reach a unique feature among major rivers draining the eastern flank of the southern rocky mountain front radiocarbon dated charcoal from terrac

an application of spectral image analysis to soil micromorphology 1 methods of analysis abstract digital images of polished soil sections were produced using an eikonix scanner 4096 detectors in a linear array separate images were collected in each of the red green and blue wavelengths of visible incandescent source light and in the blue wavelength for ultraviolet uv illumination these spectral data sets were registered displayed and analyzed as colour composite images with an easi pace spectral image analysis system visual identification and delineation of pedological features were based on their morphologies and colours this task was aided by the image enhancement capabilities of the system features classified included skeletal grains void space mottles organic material manganese concretions carbonates and depletion zones an interpretive colour code for image display of these classified soil features was proposed and implemented the percentages of the total image area occupied by each of these pedological features were derived from the final image classification

vegetation change on papa stour shetland scotland a response to coastal evolution and human interference the first palynological and related sedimentological studies from papa stour shetland are presented and supplement the limited data available for the study of holocene vegetation change from the northern isles of scotland two pollen sites were located on an isthmus which has experienced the marked influences of waterlevel changes inundation by blown shell sand and probable grazing and arable activity in spite of the unpromising calcareous nature of the mineral materials at the sites very rich suites of pollen and spore taxa were recovered including those of taxa now absent from or rare in the islands the assemblages indicate a strong interplay between two major habitat types maritime heath and grassland in addition the sites demonstrate the effects of intermittent pool formation the study shows that the vegetational and geomorphological landscapes of the study area are both dynamic and closely linked

the vorticity balance of the ocean surface in hawaii from a regional reanalysis abstractthe ocean surface vorticity budget around the hawaiian islands is examined using an 18 month model reanalysis generated using four dimensional variational state estimation with all available observations satellite in situ and high frequency radio to better resolve the ocean surface currents and reduce the representation error of the radio measured surface currents this study developed a new vertical scheme for the regional ocean modeling system a new detailed description of the ocean surface vorticity is created revealing a region dominated by cyclonic anticyclonic vorticity to the north south of the mean position of the hawaii lee countercurrent advection of vorticity is the primary process that transports the vorticity generated in the lee of the islands by the wind wake in this island lee the zonal wavenumber spectra show a cascade of vorticity energy from the submesoscale toward the larger scales latitudinal differences in the advection of vorticity spectra indicate the propag

semiannually alternating exchange of intermediate waters east of the philippines intermediate water exchange in the northwest tropical pacific is explored with the temperature salinity and current measurements of a mooring system deployed at 8 degrees n 127 05 degrees e during 2010 2014 for the first time prominent semiannual variability sav with the maximum power at similar to 187days of subthermocline meridional flow along the mindanao coast is revealed a significant correlation between meridional flow and salinity is found at intermediate depths this provides direct evidence for the alternating transports of south pacific and north pacific intermediate waters by northward and southward undercurrents respectively further analysis with an eddy resolving ocean general circulation model demonstrates that the sav is generated locally near the western boundary manifesting as large scale subthermocline recirculation and leading to alternating northward and southward flows near the mindanao coast which plays an efficient role in the intermediate water exchange of the northwest tropical pacific mechanisms underlying the observed sav are discussed

the use of image analysis in the micromorphological study of old cultivated soils an evaluation based on soils from the island of papa stour shetland this paper presents data from the first part of a major project designed to investigate the micromorphology of cultivated soils in particular the initial phase of the project is concerned with an investigation into methods for the identification and quantification of cultivation features in soil thin sections using image analysis techniques in 1993 a range of soil samples of known cultivation contexts were taken from an abandoned farm at olligarth which is located on the small island of papa stour to the immediate west of mainland shetland cultivation on this farm was carried out using a delling spade until the late 1940s samples from four contrasting sites at olligarth site 6 a planticrue site 7 the kale yard site 8 small fields and site 9 heathland were subsequently analysed for total phosphate organic content expressed as loss on ignition image analysis and traditional soil micromorphology were undertaken on samples from these sites results from the image analysis traditional micromorphological analysis and chemical analysis for each site were compared overall it was found that image analysis can contribute significantly to micromorphological description and interpretation of old cultivated soils however image analysis should not be seen as providing a replacement for the standard description of thin sections instead the use of image analysis in the study of ancient cultivated soils should not be undertaken in isolation other forms of analyses phosphate pollen organic matter traditional micromorphology should be undertaken in combination with image analysis in order to investigate the formation of cultivated soils 1996 academic press limited

stratigraphic and geomorphologic evidence of three mis 2 glacial advances in the south fork hoh river valley olympic mountains washington usa the geomorphology and stratigraphy of the south fork hoh river sf hoh olympic mountains washington allow for greater understanding of marine oxygen isotope stage 2 mis 2 ice fluctuations glacial dynamics and sedimentation age control from optically stimulated luminescence and radiocarbon dating constrains deposited sediments associated with four late pleistocene ice marginal positions that formed under reduced ice volume conditions compared with mis 3 5 glaciers in the same drainage the earliest mis 2 ice margin extended into the main hoh river valley pre sf 1 28 ka to 23 0 ka after retreat the ice occupied three closely spaced ice marginal positions sf 1 3 that range in age from 22 0 ka to shortly after 18 7 ka while the sf 1 and sf 3 positions were previously identified as the twin creeks i and ii positions the intermediate sf 2 position had not been recognized moraines are composed of poorly sorted but stratified sediment and few tills diamicton units show evidence of water reworking this research documents a detailed record of mis 2 glaciation in a maritime setting in western north america and provides evidence of rapid mis 2 ice marginal fluctuations that likely reflect responses to millennial scale climatic fluctuations and may be relevant to understanding other complex mis 2 moraine sequences

updated cosmogenic chronologies of pleistocene mountain glaciation in the western united states and associated paleoclimate inferences abstract surface exposure dating with terrestrial cosmogenic nuclides tcns has become the primary method for determining numerical ages of pleistocene mountain glacial deposits and landforms in the conterminous western united states u s and in numerous other glaciated settings worldwide recent updates to models of tcn production and scaling warrant a reconsideration of published exposure ages of moraines of the last two pleistocene glaciations and associated paleoclimate inferences previously reported tcn exposure ages of moraines are recalculated here using newer production rates and scaling models for nuclides helium 3 3he beryllium 10 10be aluminum 26 26al and chlorine 36 36cl in most cases yielding significant differences from originally reported ages recalculated tcn exposure ages of moraines of the penultimate glaciation display a high degree of variability for individual landforms particularly toward the younger end of age distributions suggesting that exposure history is affected by moraine denudation and that older age modes provide the best estimate of the depositional age of these moraines oldest exposure ages of penultimate glaciation moraines are well aligned among mountain ranges across the western u s and yield a mean of 138 13 ka indicating that mountain glaciation occurred in step with global ice volume maxima during marine oxygen isotope stage 6 on average terminal moraines of the last glaciation date to 19 5 2 3 ka and correspond to the latter part of the global last glacial maximum lgm down valley recessional moraines representing prolonged glacial stabilizations or readvances to 75 of maximum lengths have a mean exposure age of 17 0 1 8 ka suggesting that these moraine positions were last occupied during heinrich stadial 1 evidence for multiple glacial culminations during the last glaciation is found in several mountain ranges and likely reflects at least two phases of late pleistocene climate an earlier phase when glaciers attained their maximum length in response to cooling during the lgm and a later phase when glaciers persisted at or readvanced to near maximum lengths in response to sustained cold temperatures and or increased precipitation

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

early local last glacial maximum in the tropical andes the local last glacial maximum in the tropical andes was earlier and less extensive than previously thought based on 106 cosmogenic ages from beryllium 10 dating from moraines in peru and bolivia glaciers reached their greatest extent in the last glacial cycle 34 000 years before the present and were retreating by 21 000 years before the present implying that tropical controls on ice volumes were asynchronous with those in the northern hemisphere our estimates of snowline depression reflect about half the temperature change indicated by previous widely cited figures which helps resolve the discrepancy between estimates of terrestrial and marine temperature depression during the last glacial cycle

timing and nature of late quaternary mountain glaciation compilations of regional to subcontinental scale mountain glacier chronologies from five continents plus hawaii examine the temporal and spatial patterns of mountain glaciation the compilations yield key insights into the nature of past fluctuations in temperature and precipitation in mountains and adjacent regions and provide baseline data for examining the dynamics of glacier responses to climate change key insights from these compilations include the wide variability of glacier responses to fluctuations in insolation temperature and precipitation and the regionally specific variations in climatic variables through late quaternary time the compilations highlight the need to improve the density and quality of geochronological data and to enhance the understanding of the links between climate and glaciation copyright 2008 john wiley sons ltd

westward propagation of annual sea level and wind signals in the western pacific ocean abstract the annual cycle of sea level variability is examined for the period 1976 1985 at seven stations that lie along the mere axis near 7 n of the north equatorial countercurrent necc sea level trough in the western pacific the technique of complex demodulation is used to describe the year to year modulation of the phase and amplitude of the annual cycle of sea level along this line this technique reveals differences in the character of the annual cycle that are related to the occurrence of the el nino southern oscillation enso phenomenon during non enso time periods the amplitude of the annual cycle averages 4 5 centimeters and increases towards the west at approximately 1 mm per degree of longitude the annual cycle during thew periods also shows a phase propagation towards the west at about 50 cm s which is comparable to the rossby wave phase speed at this latitude during the enso events the amplitude of the annual cycle averages 7 8 centimeters and increases towards the west at about

relict properties of anthropogenic deep top soils as indicators of infield management in marwick west mainland orkney relict properties of anthropogenic deep top soils formed between the late 1200s and late 1800s are used to identify infield management practices in the coastal area of marwick west mainland orkney properties examined include particle size distribution total phosphate 13c values and micromorphological features interpretation of infield management practices from these properties is based upon their known characteristics through comparisons with known materials and by comparisons with other areas of the marwick landscape the observed properties suggest that manuring practice involved the application of grassy turf material that came exclusively from the hill land together with composted animal manure and a minor seaweed component materials from other possible sources were not utilized and differences in relict soil properties within and between the deep top soils in marwick suggest that varying proportions of turf and manure were applied across the area of land that developed as deep top soil cultivation practices associated with the deep top soils were sufficiently intense to contribute to the downslope and down profile movement of fine material the implications of the interpretations are discussed in relation to the wider organization of the cultural landscape in orkney more general conclusions are drawn on the implications for soils based studies of infield systems

interannual fluctuations of the mindanao current inferred from sea level some recent hypotheses for the el nino southern oscillation enso imply that fluctuations of the mindanao current may be involved in the early stages of the phenomenon in this paper first the relatively sparse knowledge of this southward flowing western boundary current is reviewed and then the difference in sea level between the islands of mindanao in the philippines and malakal in palau is used as an index of mindanao current fluctuations the difference series spans the period 1974 through 1985 encompassing the 1976 and 1982 1983 enso events in addition the somewhat anomalous but non enso 1980 year is included in the record the dominant signal in the sea level difference is a biannual oscillation estimated transport changes are at least 16 sv or about 50 of the mean transport in the year prior to the two enso events the mindanao current is relatively weak while during the enso year the current is stronger than average however the strongest fluctuations occur in the non enso period 1979 1980 and there is no apparent relationship between the fluctuations of the mindanao current and the strength of the enso signal

age dating and the orbital theory of the ice ages development of a high resolution 0 to 300 000 year chronostratigraphy using the concept of orbital tuning a continuous high resolution deep sea chronostratigraphy has been developed spanning the last 300 000 yr the chronology is developed using a stacked oxygen isotope stratigraphy and four different orbital tuning approaches each of which is based upon a different assumption concerning the response of the orbital signal recorded in the data each approach yields a separate chronology the error measured by the standard deviation about the average of these four results which represents the best chronology has an average magnitude of only 2500 yr this small value indicates that the chronology produced is insensitive to the specific orbital tuning technique used excellent convergence between chronologies developed using each of five different paleoclimatological indicators from a single core is also obtained the resultant chronology is also insensitive to the specific indicator used the error associated with each tuning approach is estimated independently and propagated through to the average result the resulting error estimate is independent of that associated with the degree of convergence and has an average magnitude of 3500 yr in excellent agreement with the 2500 yr estimate transfer of the final chronology to the stacked record leads to an estimated error of 1500 yr thus the final chronology has an average error of 5000 yr