holocene coastal glaciation of alaska holocene uctuations of the three cirque glaciers on the seward peninsula and ve groups of tidewater and land terminating glaciers along the northernmost gulf of alaska provide a proxy record of late holocene climatic change furthermore the movements of the coastal glaciers were relevant to late holocene native american migration the earliest expansion was recorded about 6850 yr bp by hubbard glacier at the head of yakutat bay in the gulf of alaska however its down fjord advance to the bay mouth was delayed until 2700 bp similarly expansions of the icy bay bering and mccarty glaciers occurred near their present termini by 3600 3000 bp compatible with marked cooling and precipitation increases suggested by the alaskan pollen record decrease in glacier activity 2000 bp was succeeded by advances of gulf coastal glaciers between 1500 and 1300 bp correlative with early medieval expansions across the northern hemisphere a medieval optimum encompassing at least a few centuries prior to ad 1200 is recognized by general retreat of land terminating glaciers but not of all tidewater glaciers little ice age advances of land based glaciers many dated with the precision of tree ring cross dating were centered on the middle 13th or early 15th centuries the middle 17th and the last half of the 19th century a d strong synchrony of these events across coastal alaska is evident 2000 elsevier science ltd all rights reserved

uranium series dating of pedogenic silica and carbonate crater flat nevada a 230th 234u 238u dating study on pedogenic silica carbonate clast rinds and matrix laminae from alluvium in crater flat nevada was conducted using small sample thermal ionization mass spectrometry tims analyses on a large suite of samples though the 232th content of these soils is not particularly low mostly 0 1 9 ppm the high u content of the silica component mostly 4 26 ppm makes them particularly suitable for 230th u dating on single 10 to 200 mg totally digested samples using tims we observed that 1 both micro within rind and macro stratigraphic mappable deposit order of the 230th u ages were preserved in all cases 2 back calculated initial 234u 238u fall in a restricted range typically 1 67 0 19 so that 234u 238u ages with errors of about 100 kyr 2 could be reliably determined for the oldest 400 to 1000 ka rinds and 3 though 13 of the samples were 350 ka only three showed evidence for an open system history even though the sensitivity of such old samples to isotopic disruption is very high an attempt to use leach residue techniques to separate pedogenic from detrital u and th failed yielding corrupt 230th u ages we conclude that 230th u ages determined from totally dissolved multiple sub mm size subsamples provide more reliable estimates of soil chronology than methods employing larger samples chemical enhancement of 238u 232th or isochrons

late holocene glacial activity of bridge glacier british columbia coast mountains bridge glacier is a prominent eastward flowing valley glacier located on the east side of the pacific ranges within the southern british columbia coast mountains the terminus of bridge glacier has retreated at rates up to 125 m year over the last 50 years and currently calves into proglacial bridge lake field investigations of the recently deglaciated terrain and moraines led to the discovery of detrital boles and glacially sheared stumps dendroglaciological analyses of this subfossil wood produced five radiocarbon controlled floating tree ring chronologies the relative age and stratigraphic location of these samples revealed that bridge glacier experienced at least four periods of significant advance during the late holocene a tiedemann aged advance ca 3000 14c years bp an unattributed advance ca 1900 14c years bp a first millennium advance ca 1500 14c years bp and a little ice age advance beginning ca 700 14c years bp lichenometric investigations at eight terminal and lateral moraine comple

the sedimentary record and neoglacial history of tide lake northwestern british columbia tide lake was the largest glacier dammed lake in british columbia before its demise in the early twentieth century situated in the northern coast mountains the lake was impounded by frank mackie glacier and its neoglacial end moraine a study of tide lake has provided information on styles of glaciolacustrine sedimentation and the chronology of the neoglacial interval much of the sediment underlying the floor of tide lake was transported by subglacial and proglacial meltwater streams flowing from nearby glaciers during the last phase of the lake large subaqueous fans were built in front of berendon and frank mackie glaciers and deltas formed on the east side of the basin rhythmically bedded fine sediments which cover much of the lake floor but are almost completely lacking on the slopes above were deposited from underflows originating on deltas and subaqueous fans and by fallout from interflows and overflows three major and one minor lake phases are recognized from stratigraphic geomorphic radio

tree ring crossdates for a first millennium ad advance of tebenkof glacier southern alaska tree ring crossdates from glacially killed logs show that tebenkof glacier advanced into a forefield forest in the ad 710s and 720s recession from this first millennium ad fma advance occurred before the 950s after which the ice margin readvanced in the 1280s to 1320s at the start of the little ice age lia a more extensive lia advance was underway from the 1640s to 1670s and the terminus stayed at or near its lia maximum until the 1890s these are the first absolute tree ring crossdates for a fma glacier advance in north america and support growing evidence from northwestern north america and europe for a significant cool interval in the centuries around ad 500

wavelet analysis for the regional residual and local separation of potential field anomalies a method based on the discrete wavelet transform was applied to the regional residual separation of potential fields and to the filtering of local anomalies a specific space scale wavelet analysis called multiresolution analysis allowed decomposition of the signal with respect to a vast range of scales different analysing wavelets were applied to anomalies in both synthetic and real cases but the more appropriate basis needed to be chosen by requiring the maximum compactness for the multiresolution analysis moreover since such analysis was found not to be shift invariant the same criterion was applied to choosing the best signal shift application of the technique to both synthetic and real cases produced an optimal space scale representation of the fields and a consistent regional residual separation furthermore the space localization allowed a variety of filtered signals to be obtained each one with a specific scale and local area content fourier and wavelet analyses were both applied to the filtering out of the intense etna anomaly from the aeromagnetic field of sicily the wavelet method was more powerful suppressing only the etna volcano anomaly and leaving the rest of the map practically unchanged

stratigraphic evidence for multiple holocene advances of lillooet glacier southern coast mountains british columbia holocene lateral moraines in the coast mountains of british columbia are commonly composed of multiple drift units related to several glacier advances in this paper we document lateral moraine stratigraphy at lillooet glacier in the southern coast mountains five tills separated by laterally extensive paleosols and layers of large woody debris were found in three cross sectional exposures through the northeast lateral moraine and two shallow gullies incised into its steep proximal face eighteen new radiocarbon ages constrain the timing of five separate advances of lillooet glacier 1 prior to 3000 14 c years bp 2 3000 14 c years bp 3 2500 14 c years bp 4 1700 to 1400 14 c years bp and 5 during the little ice age lia after 470 14 c years bp the lillooet glacier chronology is broadly synchronous with other glacier records from the coast mountains these records collectively demonstrate climate variability at higher frequencies during the late holocene than is apparent from many paleoecological reconstructions reconstructions of glacier fluctuations are often hampered by poor preservation of landforms that predate the extensive lia advances of the latest holocene our results highlight the potential of lateral moraine stratigraphy for reconstructing these earlier events

latest pleistocene and holocene behaviour of franklin glacier mt waddington area british columbia coast mountains canada franklin glacier is an 18 km long valley glacier that originates in a broad icefield below the west face of mt waddington in the central british columbia coast mountains canada radiocarbon dated

transpression and extensional collapse steep belts and flat belts in the appalachian central mobile belt northern new brunswick canada models of the appalachian caledonian orogen infer oblique collision and an enigmatic reversal from sinistral silurian to dextral devonian transpression the miramichi highlands in canada are relevant to such models because 1 they are a subductional thrust complex in which the inferred reversal coincided with recumbent folding and 2 its kinematic indicators include rotated thrust structures and conjugate sets of coeval structures both are easily mistaken as evidence for sinistral and dextral transpression the thrust complex is part of the appalachian central mobile belt and is partitioned into steep belts and flat belts according to the attitude of the schistosity we argue that the steep belts are coeval with late silurian plutonism and low pressure metamorphism representing transpressional zones d 2 in which the extension lineation of d 1 thrusting was tilted twice first from gentle to steep then back to a gentle plunge the transpression was synchronous with exhumation as well as sedimentation flat belts represent a later flattening d 3 that probably resulted from extensional collapse and preceded early devonian dextral transpression d 4 along the central mobile belt our model for the flat belts differs principally from models proposed for equivalent flat belts in newfoundland

a new formation process for calcic pendants from pahranagat valley nevada usa and implication for dating quaternary landforms abstract it has been assumed that soil pendants form in a similar manner as stalactites in which innermost laminae are the oldest and outer laminae are the youngest this study presents a new interpretation for soil pendant development pahranagat valley nevada pendants contain features indicating continued precipitation through time at the clast pendant contact implying that the oldest deposits are not always found at the pendant clast contact as other studies have assumed these features include a void at the clast pendant contact where minerals such as calcium carbonate silica and or fibrous silicate clays precipitate in addition fragments of the parent clast and detrital grains are incorporated into the pendant and are displaced and or dissolved and result in the formation of sepiolite this study indicates that pendants are complex open systems that during and after their formation undergo chemical changes that complicate their usefulness for dating and paleoenvironmental analyses

glacier fluctuations during the past millennium in garibaldi provincial park southern coast mountains british columbia the little ice age glacier history in garibaldi provincial park southern coast mountains british columbia was reconstructed using geomorphic mapping radiocarbon ages on fossil wood in glacier forefields dendrochronology and lichenometry the little ice age began in the 11th century glaciers reached their first maximum of the past millennium in the 12th century they were only slightly more extensive than today in the 13th century but advanced at least twice in the 14th and 15th centuries to near their maximum little ice age positions glaciers probably fluctuated around these advanced positions from the 15th century to the beginning of the 18th century they achieved their greatest extent between a d 1690 and 1720 moraines were deposited at positions beyond present day ice limits throughout the 19th and early 20th centuries glacier fluctuations appear to be synchronous throughout garibaldi park this chronology agrees well with similar records from other mountain ranges and with reconstructed n

glacier fluctuation and tree ring records for the last millennium in the canadian rockies tree ring series and records of alpine glacier fluctuations provide complementary evidence to reconstruct decade to century climate fluctuations over the last millennium in the canadian rockies tree line ring width chronologies in this area are temperature sensitive and long ca 900 years series from sites adjacent to bennington and athabasca glaciers show synchronous declines in ring width during the periods ca 1170 1180 1280 1290 1330 1350 1430 1450 1530 1540 1690 1705 and 1810 1825 a d the latter two events are replicated in many shorter tree ring chronologies and immediately precede the two major periods of moraine development ca 1700 1725 and 1825 1875 a d during the little ice age dendrochronological dating of glacially overridden trees 0 5 1 0 km upvalley of 18th century maximum positions indicate that robson and peyto glaciers were advancing between 1150 and 1350 a d during the earliest phase of the little ice age in the canadian rockies available tree ring data suggest that the level and pattern of climate variability during the 18th and 19th centuries extends back over the last milennium it is also hypothesised that glaciers attained their maximum holocene extent during the little ice age because of the interaction between these decade to century scale fluctuations and the progressive long term decline of incoming summer solar radiation in the northern hemisphere over the last 10 000 years

borehole magnetics navigation an example from the stratmat deposit bathurst new brunswick information acquired from studies of borehole core or from borehole geophysical logs form an integral part of all mineral and oil exploration programs yet as is the case of any survey the value of that information is dependent upon how well the location of each observation point is known location information becomes especially critical when the resource target has limited depth extent for example a location error of 10 m when evaluating a 5 m thick gold vein can make the difference between an economic and noneconomic deposit the trajectory of a borehole is commonly computed using an array of data points that are acquired progressively with increasing distance along the borehole depending on the type of survey employed observation points may be sparse static readings at a limited number of points or redundant dynamic surveys where the distance between observation points is less than the length of the rigid probe at each observation point three parameters are normally acquired a inclinatio

tree ring analysis and quaternary geology principles and recent applications abstract variations in annual growth rings can be utilized to assign precise calendar dates to the study of quaternary geologic or geomorphic events such as earthquakes mass movements glaciations and flooding living trees may provide the necessary absolute dates of events or minimum ages for surfaces crossdating among living trees and with subfossil wood can identify missing rings and extend tree ring chronologies further back in time these methods can lead to the accurate dating of tree rings in both living and dead trees that may have been affected by a geomorphic process the dating of partial to complete ring growth compression and release as well as dating externally apparent responses such as tree scarring or root sprouting can often lead to the identification of the season and the year an event occurred ring width patterns when compared with control chronologies can reveal the growth anomalies in witness trees that may be related to geomorphic events examples of the application of tree rings to quaternary geology and geomorphology are varied and numerous root shearing topping of trees and missing rings tie a rupture along the san andreas fault to the year 1812 a d narrow tree rings linked to defoliation and tephra fallout differentiated distinct eruptions of mt st helens in 1480 and in 1482 a d ring analysis has helped unravel glacial chronologies and tree ring linkages with climate have also verified that late holocene ice advances in argentina correlated with intervals of cool wet summers in another application an 1818 a d quebec landslide has been tied to the growing season whereas slides dated to 1834 and 1846 a d occurred during the spring

little ice age glacial activity in the mt waddington area british columbia coast mountains canada the establishment of fourteen little ice age lia glacier chronologies in the mt waddington area led to the development of an extended history of glacial activity in this portion of the southern british columbia coast mountains canada the glaciers were located within four different mountain ranges and were of varying size and aspect dendrochronological and lichenometric techniques were used to provide relative age estimates of moraines formed as glacier termini retreated from advanced positions evidence for pre lia glacial events is best preserved at tiedemann glacier where the oldest glacial advances date to a d 620 and 925 933 soil covered and well vegetated moraines built at cathedral pagoda and siva glaciers date to between a d 1203 and 1226 following this event moraines constructed at ragnarok siva and cathedral glaciers in the mid 14th century suggest glaciers in the region underwent a period of downwasting and retreat before readvancing the majority of moraines recorded in the mt waddington area describe late lia glacial events shown to have constructed moraines that date to a d 1443 1458 1506 1524 1562 1575 1597 1621 1657 1660 1767 1784 1821 1837 1871 1900 1915 1928 and 1942 1946 over the last 500 years these moraine building episodes were shown to occur on average every 65 years and suggest there has been prolonged synchronicity in the glaciological response to persistent climate forcing mechanisms nevertheless our analysis suggests that local factors such as aspect and size play an important role in individual glacial response notably ice termini of medium size glaciers facing eastwards showed a quicker response to climatically induced mass balance changes resume l historique de quatorze glaciers de vallee de la region du mont waddington sud de la chaine cotiere de colombie britannique canada durant le petit ge glaciaire pag fut evalue par l utilisation de techniques dendrochronologiques et lichenometriques procurant un ge minimum pour la formation des moraines laterales et frontales multiples les glaciers a l etude d aspect et de taille differents furent selectionnes a partir de quatre chaines de montagnes les evenements qui predatent le pag sont le mieux preserves sur le site du glacier tiedemann ou les plus vieilles avancees glaciaires date de a d 620 et 925 933 des moraines presentant une pedogenese avancee et recouvertes d une dense couverture vegetale furent datees entre a d 1203 et 1226 des moraines construites dans le milieu du 14 e siecle par les glaciers ragnarok siva et cathedral suggerent que les glaciers de la region se sont retires pour par la suite reavancer la majorite des moraines datees le furent vers la fin du pag soit en a d 1443 1458 1506 1524 1562 1575 1597 1621 1657 1660 1767 1784 1821 1837 1871 1900 1915 1928 et 1942 1946 au cours des 500 dernieres annees en moyenne 65 annees separent les differents episodes glaciaires ce qui suggerent un synchronisme des reponses glaciaires aux mecanismes climatiques des donnees preliminaires suggerent que l orientation et la taille des glaciers jouent un role important dans la reponse individualiste des glaciers en fait les terminus glaciaires des moyens glaciers d orientation est semblent repondre plus rapidement a un ajustement de volume interne glaciaire

late holocene glacial activity at bromley glacier cambria icefield northern british columbia coast mountains canada retreating and downwasting glaciers in the british columbia coast mountains are exposing the remains of forests buried during holocene age glacial advances despite recent progress in discerning th

did rock avalanche deposits modulate the late holocene advance of tiedemann glacier southern coast mountains british columbia canada abstract most glaciers in western north america with reliable age control achieved their maximum holocene extents during final advances of the little ice age tiedemann glacier a large alpine glacier in western canada is an enigma because the glacier constructed lateral moraines that are up to 90 m higher and extend 1 8 km farther downvalley than those constructed during the little ice age our data show that the activity of the glacier is more complex than originally documented and that the glacier advanced many times during the past six thousand years surface exposure dating and radiocarbon ages of stumps beneath till demonstrate that the glacier achieved its maximum holocene extent at about 2 7 ka we hypothesize that one or more rock avalanches delivered surface debris to the glacier and caused the 2 7 ka glacier advance to be much larger than can be explained by climate forcing to test our hypothesis we developed and used a surface debris advection routine coupled to an ice dynamics model our results show that even a moderately sized rock avalanche 10 10 6 m 3 delivered to the top of the ablation zone could cause the glacier to thicken and advance far beyond its little ice age limit

regional gravity setting of the sudbury structure in the vicinity of sudbury ontario canada the boundary between the southern and superior tectonic provinces is overlain by the elliptical sudbury structure on the basis of gravity modeling genesis of the sudbury structure has been attributed to either a magmatic origin having a dense hidden differentiate zone or a meteorite impact origin there being no dense hidden mass the difference between the two gravity models centers on the problem of regional residual separation as shown by numerous previous studies any such separation of components is nonunique this becomes especially problematic when as in sudbury a portion of the near surface geology has a similar orientation and dimension to more deep seated sources in this paper several numerical methods upward continuation downward continuation wavelength filtering trend surface analysis for determining the regional component of the gravity field associated with the sudbury structure have been applied and evaluated of the numerical methods used the upward and downward continuation operators provided the most insight into the deep structural controls of the sudbury basin our preferred interpretation of the regional gravity field invokes a two component structure underlying the southern half of the sudbury structure is a laterally continuous gravity anomaly that is probably associated with a zone of uplifted huronian volcanics the gravity anomaly under the northern portion of the sudbury structure has a more restricted spatial extent the close association between the northern limit of the gravity anomaly and the surface outcrop of the levack gneiss suggests the source of this anomaly is probably a slab of dense levack gneiss this interpretation favors a meteorite impact origin for the sudbury structure

mid holocene glacier expansion between 7500 and 4000 cal yr bp in the british columbia coast mountains canada the mid holocene behaviour of five glaciers in the british columbia coast mountains was reconstructed from radiocarbon ages and stratigraphic analysis subfossil wood evidence at canoe fyles jaco

magnetite mapping with a multicoil airborne electromagnetic system the information content of data from an in phase quadrature electromagnetic em system consists of a combination of conductive eddy current response and magnetic polarization response the secondary field resulting from conductive eddy current flow is frequency dependent and consists of both in phase and quadrature components of positive sign conversely the field resulting from magnetic polarization is commonly frequency independent and consists of only an in phase component of negative sign a magnetite mapping technique was developed for the horizontal coplanar coils of a closely coupled multicoil airborne em system the technique yields contours of apparent weight percent magnetite when using a homogeneous half space model the method can be complementary to magnetometer mapping in certain cases compared to magnetometry it is far less sensitive but is more able to resolve closely spaced magnetite zones the method is also independent of remanent magnetism and magnetic latitude it is sensitive to

neoglaciation in the southern coast mountains of british columbia chronology prior to the late neoglacial maximum moraine stratigraphy and morphology radiocarbon dates from klinaklini franklin tiedemann gilbert and bridge glaciers and related information from elsewhere in the coast mountains are used to construct a chronology for glacier fluctuations the garibaldi phase of glacier expansion 6000 5000 14c years bp at the end of the early holocene xerothermic interval is indicated by overridden tree stumps the mid neoglacial tiedemann advance 3300 1900 14c years bp is represented by moraines till and meltwater sediments at three glaciers but only tiedemann glacier attained its greatest holocene extent at this time late neoglacial expansion commenced before 900 14c years bp and continued without notable interruption until glaciers achieved their maximum post pleistocene expansion during the eighteenth and nineteenth centuries evidence for the garibaldi and tiedemann events is scarce within the coast mountains because of the more extensive late neoglacial advance however correlative advances have been

multi proxy record of holocene glacial history of the spearhead and fitzsimmons ranges southern coast mountains british columbia abstract evidence from glacier forefields and lakes is used to reconstruct holocene glacier fluctuations in the spearhead and fitzsimmons ranges in southwest british columbia radiocarbon ages on detrital wood and trees killed by advancing ice and changes in sediment delivery to downstream proglacial lakes indicate that glaciers expanded from minimum extents in the early holocene to their maximum extents about two to three centuries ago during the little ice age the data indicate that glaciers advanced 8630 8020 6950 6750 3580 2990 and probably 4530 4090 cal yr bp and repeatedly during the past millennium little ice age moraines dated using dendrochronology and lichenometry date to early in the 18th century and in the 1830s and 1890s limitations inherent in lacustrine and terrestrial based methods of documenting holocene glacier fluctuations are minimized by using the two records together

late holocene fluctuations of the bear river glacier northern coast ranges of british columbia canada during holocene advances of the bear river glacier in northwestern british columbia ice pushed against a bedrock slope on the north side of bear river pass as it was being diverted eastward and westward along the pass the result is a series of till sheets plastered against the rock slope and separated by wood mats this sequence of tills provides an unusually detailed record of early neoglacial history and shows that neoglacial expansion in the northern coast mountains began earlier than previously known moraines show the extent of little ice age expansion and documents related to the long mining history of the area provide records of post lia recession the oldest deposits in the area are a small lateral moraine outside of a prominent lia moraine and a till in the pass older than c 3500 14c yr bp the small moraine is undated it may be equivalent to the latest pleistocene crowfoot advance which produced similar moraines in the southern coast mountains and eastern cordillera wood mats in the pa

calendar dated glacier variations in the western european alps during the neoglacial the mer de glace record mont blanc massif holocene glacier records from the western european alps are still sparse although a number of sites are well suited to constraining pre and early little ice age lia glacier advances the present study provides the first dendrochronologically based and calendar dated neoglacial glacier chronology for the mont blanc massif french alps it is based on the analysis of over 240 glacially buried pinus cembra subfossil logs and wood remains found either embedded in till or as detrital material in the mer de glace right lateral moraine only a few of the samples were found to be formally in situ but we show that some logs were virtually in situ not rooted but showing little or no evidence of reworking and could be used to accurately reconstruct past glacier margin behavior in space and time uncertainties regarding the other samples may relate to original growth location and or to outer wood decay the resulting dates followed by a were therefore considered maximum limiting ages for glacier advances the main burial events interpreted as glacier advances occurred between ca 1655 and 1544 bc between ca 1230 and 1105 bc between ca 1013 and 962 937 bc at ca 802 777 bc after 608 bc between 312 and 337 ad between ca 485 ad and 606 ad between 1120 and 1178 ad between ca 1248 and 1278 1296 ad and after 1352 ad these advances predate the late lia maxima known from historical sources the magnitude of the advances gradually increased to culminate in three near neoglacial maxima during the 7th 12th and 13th centuries ad followed by a first lia neoglacial maximum in the second half of the 14th century ad the pattern of neoglacial events described here is coherent with central and eastern alpine glacier chronologies this indicates marked synchronicity of late holocene glacier variability and forcing at a regional scale although occasional differences could be detected between western and eastern records the mer de glace record also confirms the link between the timing of sediment erosion in a high elevation glaciated alpine catchment and subsequent deposition in the sub alpine lake bourget

factors and processes governing the 14c content of carbonate in desert soils epsl elsevier earth and planetary science letters 125 1994 385 405 factors and processes governing the 14c content of carbonate in desert soils ronald amundson a yang wang a oliver chadwick b susan trumbore c leslie mcfadden d eric mcdonald d steven wells e michael deniro f a division of ecosystem sciences 108 hilgard university of california berkeley ca 94720 usa b earth sciences division jet propulsion laboratory pasadena ca 91109 usa c department of geosciences university of california irvine ca 92717 usa d department of earth and planetary sciences university of new mexico albuquerque nm 87131 usa e department of earth sciences university of california riverside ca 92521 usa f department of geological sciences university of california santa barbara ca 93106 usa received 1 september 1993 revision accepted 14 april 1994 abstract a model is presented describing the factors and processes which determine the measured 14c ages of soil calcium carbonate pedogenic carbonate forms in isotopic equilium with soil co 2 carbon dioxide in soils is a mixture of co 2 derived from two biological sources respiration by living plant roots and respiration of microorganisms decomposing soil humus the relative proportion of these two co z sources can greatly affect the initial 14c content of pedogenic carbonate the greater the contribution of humus derived co 2 the greater the initial 14c age of the carbonate mineral for any gwen mixture of co 2 sources the steady state co 2 distribution vs soil depth can be described by a production diffusion model as a soil ages the 14c age of soil humus increases as does the steady state 14c age of soil co 2 and the initial 14c age of any pedogenic carbonate which forms the mean 14c age of a complete pedogenic carbonate coating or nodule will underestimate the true age of the soil carbonate this discrepancy increases the older a soil becomes partial removal of outer and younger carbonate coatings greatly improves the relationship between measured 14c age and true age although the production diffusion model qualitatively explains the 14c age of pedogenic carbonate vs soil depth in many soils other factors such as climate change may contribute to the observed trends particularily in soils older than the holocene 1 introduction r a d i o c a r b o n d a t i n g o f s e d i m e n t a r y d e p o s i t s in d e s e r t s is h i n d e r e d by a lack o f o r g a n i c carbon paradoxically most o f the d e p o s i t s in t h e s e re mk gions a r e b l a n k e t e d with i n o r g a n i c c a r b o n in the f o r m o f p e d o g e n i c c a r b o n a t e since t h e early 1960s 14c ages have b e e n c a l c u l a t e d for t h e s e c a r b o n a t e s 1 fig 1 illustrates t h a t an a p p r o x i m a t e 1 1 r e l a t i o n s h i p exists b e t w e e n 14c ages of soil c a r b o n a t e a n d coexisting o r g a n i c m a t e r i a l s a n d ages d e t e r m i n e d by o t h e r m e a n s see also 2 3 t h e s e r e l a t i o n s h i p s a r e n o t perfect s o m e c a r b o n a t e is y o u n g e r t h a n i n d e p e n d e n t ages sug 0012 821x 94 07 00 1994 elsevier science b v all rights reserved ssdi 0012 821x 94 00097 i

environmental reconstruction from a varve network in the southern coast mountains british columbia canada cores of annually laminated sediments varves from five lakes in the southern coast mountains of british columbia canada document clastic sediment response to climate and geomorphic change over the past 120 years interannual varve thickness correlates with annual flood magnitude interdecadal trends in varve thickness are influenced by other environmental factors such as glacier recession despite major differences in the lakes and their contributing watersheds substantial concordance is observed among the records a pronounced change in the nature of lake sedimentation accompanied by higher interannual variability occurred in 1980 the change coincides with an increase in the magnitude of autumn flooding and major re organization of the north pacific climate system these results highlight new directions for palaeoenvironmental research using varved sediment records specifically to study the magnitude and spatial extent of past hydro climatic events

diagenetic replacement controlled by force of crystallization many diagenetic replacements in sedimentary rocks occur along thin solution films between the authigenic and host phases rather than conventionally invoking bulk pore water undersaturation for host phase dissolution we propose that many diagenetic replacements occur by a force of crystallization controlled replacement mechanism whereby nonhydrostatic stresses resulting from authigenic crystal growth are principally responsible for host phase dissolution this model explains diagenetic features such as the restriction of host phase dissolution to authigenic host crystal contacts and euhedral authigenic crystal faces in planar contact with unreplaced host phases as well as the relative replacement tendencies of some common authigenic minerals

dendroglaciological evidence for holocene glacial advances in the todd icefield area northern british columbia coast mountains accelerated glacial recession and downwasting in pacific north america is exposing land surfaces and fea tures buried by glacial advances that in many locations predate the recent little ice age lia dendrochronologic analyses of increment core samples from living trees abies lasiocarpa tsuga mertensiana and samples of subfossil wood collected in the todd icefield area boundary ranges british columbia coast mountains provide the basis for a dendroglaciological and radiocarbon based reconstruction of late holocene glacier activity five intervals of glacier ex pansion were recorded by trees killed or buried by advancing glaciers 1 an advance prior to 3000 14 c years bp 2 an advance at 3000 14 c years bp that coincides with the regional tiedemann advance 3 an unattributed advance at 2300 14 c years bp 4 a two phase advance at 1700 and 1450 14 c years bp that corresponds with the regional first millennium advance 5 an advance with three phases of expansion that began prior to 750 14 c bp and is con sistent with the regional early lia interval and a two phase interval of late lia expansion culminating after 240 and 100 years bp this chronology of late holocene glaciation matches that emerging from similar investigations in the coastal cordillera of pacific north america and provides additional support for the regional significance of both the tiedemann and the first millennium advances resume une recession et une fonte glaciaire accelerees dans l ocean pacifique en amerique du nord exposent des sur faces de terrain et des traits caracteristiques enfouis sous des avancees glaciaires lesquelles dans bien des cas datent d avant le recent petit ge glaciaire des analyses dendrochronologiques d echantillons proportionnels de carottes pris

dendroglaciological investigations of mid to late holocene glacial activity in the mt waddington area british columbia coast mountains canada dendroglaciological investigations near mt waddington in the central british columbia coast mountains provide an enhanced perspective of holocene glacial activity field investigations at confederation franklin and jambeau glaciers led to the discovery of subfossil wood mats encased in glacial deposits and glacially sheared stumps buried beneath till radiocarbon dated wood collected from valley bottom and lateral moraine sites at confederation glacier suggest that an early holocene advance occurred at c 5665 cal yr bp followed by succeeding intervals of glacier expansion at c 3700 and 3500 cal yr bp at jambeau glacier detrital wood mats buried close to the contemporary lateral moraine crests document glacier expansion at c 3000 cal yr bp detrital subfossil wood buried in lateral moraines at the confluence of confederation and franklin glaciers records distinct episodes of little ice age glacier expansion as early as c 1212 cal yr ad and suggests the glacier surface continued to thicken u

pedogenic carbonate cutans on clasts in soils as a record of history of grassland ecosystems pedogenic carbonate cutans coatings pendants rinds on coarse clasts are common in stony soils of arid and semiarid regions dominated by open vegetation this paper gives an overview of the potential of the carbonate cutans for paleograssland research using data from literature and personal observations carbonate coatings are stratified into distinct microlamina which can provide a record of local environmental changes lamina made of a rather pure calcium carbonate with better formed and parallel oriented crystals seem to be indicative of relatively dry phases that were less favorable for biological activity a high content of admixtures poorer formed and randomly oriented calcite crystals presumably mark wetter periods characterized by climatic amelioration at a most general level n 13 c of the cutan carbonate can provide information on the type of photosynthesis of local vegetation whereas n 18 o in carbonate material of the coatings correlates with oxygen isotopic composition of precipitation water at the site and is sensitive to fluctuations in temperature to obtain chronological evidence on cutan formation the 14 c and th u methods can be applied with certain limitations additionally cutan growth rates can be used to evaluate the age of these features fl 2002 elsevier science b v all rights reserved

late holocene glacial history of scimitar glacier mt waddington area british columbia coast mountains canada scimitar glacier originates below the northeast face of mt waddington in the southern british columbia coast mountains and flows 18 km down valley to calve into a proglacial lake at several locations downwasting of the glacier surface has exposed stacked till units separated by wood bearing horizons in the proximal slopes of lateral moraines flanking the glacier historical moraine collapse and erosional breaching has also revealed the remains of standing trees buried in moraine dammed lake sediments radiocarbon and tree ring dating show that scimitar glacier expanded down valley at least three times in the late holocene the earliest evidence found for ice expansion indicates scimitar glacier was advancing in 3167 2737 cal years bp in association with the regional tiedemann advance following this advance the glacier downwasted prior to expanding in 1568 1412 cal years bp during the first millennial advance a final period phase of moraine construction was initiated during late little ice age glacia

neoglacial history of the stikine iskut area northern coast mountains british columbia information about neoglacial features was obtained from aerial photograph interpretation observations during low level flights ground checking and historical records terminal moraines at great flood and mud glaciers date from the late seventeenth to early eighteenth centuries and recessional moraines at these glaciers and terminal moraines at glaciers farther east date from the late nineteenth to early twentieth centuries these late neoglacial terminal moraines appear in general to mark the greatest post pleistocene extent of the glaciers radiocarbon dates from overridden trees and soil indicate that 500 600 14c years bp glaciers were considerably more extensive than they are at present and were advancing preservation of a 3800 14c year old caribou antler in a snowbank that is now rapidly shrinking suggests that climate has been relatively cool and moist for the past four millennia

holocene glacier fluctuations waskey lake northeastern ahklun mountains southwestern alaska lake sediments from waskey lake ahklun mountains southwestern alaska were studied to decipher the history of upvalley glacier e uctuations during the holocene several indicators of glacier activity were measured including magnetic susceptibility organic matter content grain size distribution bulk sediment mineralogy and diatom assemblages seven radiocarbon ages on macrofossils along with cross checks by tephrochronology provide the chronology of the cores the results from core wl 1 indicate that glaciers lingered near waskey lake until 9100 cal yr bp perhaps under conditions of high winter accumulation peak organic matter content occurs at 7400 cal yr bp when precipitation might have shifted to summer the onset of neoglaciation occurred 3100 cal yr bp and glaciers reached their maximum extent 700 cal yr bp this chronology is consistent with the lichenometrically dated moraines from the glacier foree elds although the ages are tentative the youngest and most widespread group of moraines was deposited sometime between 650 and 200 cal yr bp during the little ice age since then glaciers in the waskey lake area have shrunk by 50 and equilibrium line altitudes ela have risen by 35 6 22 m this rise in ela is much less than the 100 to 200 m rise observed elsewhere in alaska and indicates considerable spatial variability in late holocene climatic change

dendrogeomorphic reconstruction of little ice age paraglacial activity in the vicinity of the homathko icefield british columbia coast mountains canada article i nfo article history moraine and glacier dams bordering the homathko icefield in the southern british columbia coast mountains failed in the 1980s and 1990s causing catastrophic downstream floods the largest of the floods occurred in august 1997 and was caused by overtopping and rapid breaching of the moraine dam that impounds queen bess lake the floodwaters from queen bess lake eroded holocene age sedimentary deposits along the west fork of nostetuko river and caused a steep rise in the hydrograph of homathko river at the head of bute inlet 115 km downstream a field investigation of the eroded valley fill in 2008 revealed multiple paraglacial valley fill units many of which are capped by in situ stumps and woody detritus dendrogeomorphological field techniques were employed to develop a chronology for the buried forests a regional tree ring chronology spanning the interval ce 1572 2007 was constructed from living subalpine fi r abies lasiocarpa trees at seven sites in the southern coast mountains in cases where subfossil stumps and boles predated the regional chronology relative death dates constrained by radiocarbon ages were assigned to floating chronologies by combining these dendrogeomorphological dating methods we identified six floodplain aggradation episodes within the past 1200 years comparison to local and regional glacial histories suggests that these events reflect climate induced little ice age changes in local glacier cover

holocene glacier fluctuations in alaska abstract this review summarizes forefield and lacustrine records of glacier fluctuations in alaska during the holocene following retreat from latest pleistocene advances valley glaciers with land based termini were in retracted positions during the early to middle holocene neoglaciation began in some areas by 4 0 ka and major advances were underway by 3 0 ka with perhaps two distinct early neoglacial expansions centered respectively on 3 3 2 9 and 2 2 2 0 ka tree ring cross dates of glacially killed trees at two termini in southern alaska show a major advance in the ad 550s 720s the subsequent little ice age lia expansion was underway in the ad 1180s 1320s and culminated with two advance phases respectively in the 1540s 1710s and in the 1810s 1880s the lia advance was the largest holocene expansion in southern alaska although older late holocene moraines are preserved on many forefields in northern and interior alaska tidewater glaciers around the rim of the gulf of alaska have made major advances throughout the holocene expansions were often asynchronous with neighboring termini and spanned both warm and cool intervals suggesting that non climatic factors were important in forcing these advances however climatic warming appears to have initiated most rapid iceberg calving retreats large glaciers terminating on the forelands around the gulf of alaska may have had tidewater termini early in the holocene but have progressively become isolated from the adjacent ocean by the accumulation and subaerial exposure of their own sediments

holocene and latest pleistocene fluctuations of stutfield glacier canadian rockies the holocene and late glacial history of fluctuations of stutfield glacier are reconstructed using moraine stratigraphy tephrochronology and dendroglaciology stratigraphic sections in the lateral moraines contain tills from at least three glacier advances separated by volcanic tephras and paleosols the oldest pre mazama till is correlated with the crowfoot advance dated elsewhere to be younger dryas equivalent a neoglacial till is found between the mazama tephra and a paleosol developed on the bridge river tephra a log dating 2400 bp from the upper part of this till indicates that this glacier advance correlated with the peyto advance culminated shortly before deposition of the bridge river tephra radiocarbon and tree ring dates from overridden trees exposed in moraine sections indicate that the initial cavell little ice age lia advance overrode this paleosol and trees after a d 1271 three subsequent phases of the cavell advance were dated by dendrochronology the maximum glacier extent occurred in the mid 18th century predating 1743 on the southern lateral although ice still occupied and tilted a tree on the north lateral in 1758 subsequent glacier advances occurred ca 1800 1816 and in the late 19th century the relative extent of the lia advances at stutfield differs from that of other major eastward flowing outlets of the columbia icefield which have maxima in the mid late 19th century this is the first study from the canadian rockies to demonstrate that the large morphologically simple lateral moraines defining the lia glacier limits are actually composite features built up pro gressively but discontinuously over the holocene and contain evidence of multiple holocene and crowfoot age gla cier advances resume la stratigraphie des moraines la tephrochronologie et la dendroglaciologie des moraines ont servi a recons truire les fluctuations a l holocene et au cours de l histoire glaciaire tardive du glacier stutfield les sections stratigra phiques dans les moraines laterales contiennent des tills d au moins trois avancees glaciaires separees par des tephras volcaniques et des paleosols le plus ancien le till pre mazama est correle a l avancee crowfoot dont on a determine l ge ailleurs comme etant un equivalent du dryas recent un till de l epoque neo glaciaire se retrouve entre le tephra mazama et un paleosol developpe sur le tephra de bridge river un billot date 2400 bp provenant de la partie supe rieure de ce till indique que cette avancee glaciaire correlee a l avancee de peyto a culmine peu de temps avant la deposition du tephra de bridge river des datations au 14 c et des series chronlogiques provenant d arbres recouverts puis exposes dans des sections de moraine indiquent que l avancee cavell initiale petit ge glaciaire a chevauche ce paleosol et les arbres apres l an 1271 la dendrochronologie a permis la datation de trois phases subsequentes de l avancee cavell l etendue glaciaire maximale eut lieu au milieu du 18e siecle avant 1743 sur le cote sud bien que la glace fut encore presente sur le cote nord et y ait bascule un arbre en 1758 des avancees glaciaires subsequentes ont eu lieu vers 1800 1816 et vers la fin du 19e siecle l etendue relative des avancees du petit ge glaciaire a stutfield differe de celles d autres glaciers majeurs du champ de glace columbia s ecoulant vers l est et qui ont eu leur maxi mum dans la deuxieme moitie du 19e siecle cette etude est la premiere provenant des rocheuses canadiennes a de monter que les grandes moraines laterales morphologiquement simples definissant les limites du glacier au petit ge glaciaire sont en fait des elements composites developpes progressivement mais de facon discontinue tout au cours de l holocene et qu elles contiennent des evidences d avancees glaciaires multiples d ge holocene et crowfoot

improved edge detection mapping through stacking and integration a case study in the bathurst mining camp airborne geophysical surveys provide spatially continuous regional data coverage which directly reflects subsurface petrophysical differences and thus the underlying geology a modern geologic mapping exercise requires the fusion of this information to complement what is typically limited regional outcrop often interpretation of the geophysical data in a geological context is done qualitatively using total field and derivative maps with a qualitative approach the resulting map product may reflect the interpreter s bias source edge detection provides a quantitative means to map lateral physical property changes in potential and non potential field data there are a number of source edge detection algorithms all of which apply a transformation to convert local signal inflections associated with source edges into local maxima as a consequence of differences in their computation the various algorithms generate slightly different results for any given source depth geometry contrast and noise levels to enhance the viability of any detected edge it is recommended that one combines the output of several source edge detection algorithms here we introduce a simple data compilation method deemed edge stacking which improves the interpretable product of source edge detection through direct gridding grid addition and amplitude thresholding in two examples i e a synthetic example and a real world example from the bathurst mining camp new brunswick canada a number of transformation algorithms are applied to gridded geophysical data sets and the resulting source edge detection solutions combined edge stacking combines the benefits and nuances of each source edge detection algorithm coincident or overlapping and laterally continuous solutions are considered more indicative of a true edge whereas isolated points are taken as being indicative of random noise or false solutions when additional data types are available as in our example they may also be integrated to create a more complete geologic model the effectiveness of this method is limited only by the resolution of each survey data set and the necessity of lateral physical property contrasts the end product aims at creating a petrophysical contact map which when integrated with known lithological outcrop information can be led to an improved geological map

timing and climatic controls over neoglacial expansion in the northern coast mountains british columbia canada holocene sedimentary records from two lakes in white pass british columbia show that the onset of neoglacial sedimentation began c 2 ka cal bp prior to this time the lakes accumulated organicrich sediments with properties and sedimentation rates similar to adjacent lakes that have not had glacial influences during the holocene neoglaciation at white pass was coincident with the increased delivery of exotic tsuga heterophylla western hemlock pollen these results together with regional indications for increased delivery of hemlock pollen at 2 ka bp by a deepened low pressure in the northeastern pacific ocean suggest that increased moisture was important for the expansion of glaciers in the region in addition to longer term late holocene cooling

a gravity model for the sudbury structure along the lithoprobe seismic line previous gravity models of the sudbury structure 1850 ma were constrained by surface geology and by density measurements of surface and borehole rock samples recent high resolution seismic reflection data provide additional constraints for modeling new gravity observations made along the sudbury lithoprobe transect results indicate 1 density distributions constrained by the seismic data yield calculated gravity values matching the bouguer gravity data 2 the main sources of gravitational disturbance are external to the sudbury structure 3 the positive gravity anomaly trend south of the sudbury structure is associated with mafic rocks of proterozoic age and 4 the large ramplike gravity anomaly paralleling the northwest margin of the sudbury structure is an expression of a northward dipping boundary within the archean basement the presence of a hidden mafic layer beneath the sudbury structure is not required to model the bouguer gravity data an enigma is an 8 mgal positive gravity anomaly over the south central sudbury structure

holocene glacier fluctuations in the american cordillera abstract in many areas of the american rocky mountains colorado wyoming utah idaho montana cascade range washington oregon and the sierra nevada california radiocarbon ages suggest that ice receded to near present limits before 10 ka bp a pre altithermal readvance or stillstand left moraines ca 1 3 km beyond and ca 50 300 m below present glacier margins at one locality on glacier peak in washington these deposits are perhaps dated to the early holocene but in general these deposits are probably at least 10 ka old glacial advances during the altithermal ca 8 to 5 ka bp elsewhere are rare radiocarbon evidence for altithermal glacial advances in the colorado front range is questionable the earliest radiocarbon dated neoglacial advances occurred about 5 ka bp in the washington cascades moraines and related deposits believed to be of early neoglacial age i e 5 to 3 ka bp elsewhere are poorly dated for example moraines believed to date to the early neoglacial in colorado triple lakes and wyoming temple lake are actually late pleistocene age based on radiocarbon ages derived from lake sediments at the type localities although relative age data i e lichens rock weathering soils from many areas suggest a three fold neoglacial sequence little supporting radiocarbon evidence is available however tephrochronology distinguishes three neoglacial advances near mount rainier in washington in most mountain ranges of the western united states fresh unweathered sharp crested moraines usually adjacent to present ice margins or near headwalls in empty cirques date to the little ice age of the last several centuries however detailed photographic or other historical records of glacial fluctuations during the last century are rare and detailed mass balance studies rarer still whether or not pre little ice age glacial fluctuations in the american cordillera are synchronous must await better radiometric dating of local moraine sequences

tree ring dated little ice age histories of maritime glaciers from western prince william sound alaska tree ring studies at 13 glacier forefields in western prince william sound show little ice age glacial fluctuations were strongly synchronous on decadal timescales cross dated glacially overrun trees at eight sites indicate ice margins advanced in the early late twelfth through thirteenth centuries and middle seventeenth to early eighteenth centuries little ice age tree ring dates of 22 moraines at 13 glaciers show two main periods of stabilization the earlier of these in the first decades of the eighteenth century overlaps with the second period of glaciers overrunning trees and marks culmination of this middle little ice age expansion stabilization of moraines on nine of the study forefields in the latter part of the nineteenth century delineates a third interval of little ice age glacial advance the detailed little ice age record from land terminating glaciers in western prince william sound is consistent on a timescale of decades with four other tree ring dated glacial histories from across the northern gulf of alaska this coastal northeastern pacific glacial record reveals the structure of the little ice age in the region and provides a strong basis for comparison with other proxy climate records spanning the past 1000 years

dendroglaciological reconstruction of late holocene glacier activity at white and south flat glaciers boundary range northern british columbia coast mountains canada holocene glacier activity in the northern british columbia coast mountains canada is described following investigations in the recently deglaciated forefields of white and south flat glaciers spilling from the cambria icefield glacially overridden stumps and detrital wood was radiocarbon and dendrochronologically dated to describe an advance between ad 250 and 650 expansion and thickening of white glacier by ad 765 resulted in creation of an ice dammed lake in south flat valley that persisted until ad 1080 following this the lake drained before refilling in the early little ice age prior to ad 1300 shortly thereafter white and south flat glaciers became confluent and flowed over the valley side toward white lake the characteristics of the site and the preservation of 1500 yr old deposits indicate that the two glaciers remained confluent throughout the remainder of the little ice age only separating following terminal retreat early in the 20th century the late holocene glacial history of whit

the impact of air mass circulation dynamics on late holocene paleoclimate in northwestern north america paleoclimate records from northern british columbia southwestern yukon and adjacent alaska suggest that late holocene climate may have been influenced by specific air mass circulation dynamics the aleutian lowpressure index alpi is a measure of sea level pressure fluctuations in the pacific northwest associated with the aleutian low al pressure system in this study we show that the al has a strong influence on historical climate change in the study area and explore the relationships between alpi polarity and changes in late holocene paleoclimate records analyses of weather station data in the study area indicate positive correlations r 0 63 between mean wintertime december march temperature and alpi values total wintertime snowfall accumulation and total precipitation show moderate and weak negative correlations respectively a late holocene increase in exotic western hemlock tsuga heterophylla pollen has been observed in regional paleoclimate studies a sustained positive alpi phase during the late holocene is considered as a causative mechanism under such conditions warm maritime air masses would more frequently penetrate inland potentially resulting in eastward pollen transfer enhanced growing conditions at coastal sites and an increase eastwards in the range limit of these species this study indicates that apparent conflicts in the timing and magnitude of late holocene climate change may be the result of a strong regional climate forcing mechanism that exhibits both temporal and geographical variation r 2002 elsevier science ltd and inqua all rights reserved

latest pleistocene and holocene glacier fluctuations in western canada we summarize evidence of the latest pleistocene and holocene glacier fluctuations in the canadian cordillera our review focuses primarily on studies completed after 1988 when the first comprehensive review of such evidence was published the cordilleran ice sheet reached its maximum extent about 16 ka and then rapidly decayed some lobes of the ice sheet valley glaciers and cirque glaciers advanced one or more times between 15 and 11 ka by 11 ka or soon thereafter glacier cover in the cordillera was no more extensive than at the end of the 20th century glaciers were least extensive between 11 and 7 ka a general expansion of glaciers began as early as 8 4 ka when glaciers overrode forests in the southern coast mountains it culminated with the climactic advances of the little ice age holocene glacier expansion was not continuous but rather was punctuated by advances and retreats on a variety of timescales radiocarbon ages of wood collected from glacier forefields reveal six major periods of glacier advance 8 59 8 18 7 36 6 45 4 40 3 97 3 54 2 77 1 71 1 30 ka and the past millennium tree ring and lichenometric dating shows that glaciers began their little ice age advances as early as the 11th century and reached their maximum holocene positions during the early 18th or mid 19th century our data confirm a previously suggested pattern of episodic but successively greater holocene glacier expansion from the early holocene to the climactic advances of the little ice age presumably driven by decreasing summer insolation throughout the holocene proxy climate records indicate that glaciers advanced during the little ice age in response to cold conditions that coincided with times of sunspot minima priority research required to further advance our understanding of late pleistocene and holocene glaciation in western canada includes constraining the age of late pleistocene moraines in northern british columbia and yukon territory expanding the use of cosmogenic surface exposure dating techniques using multi proxy paleoclimate approaches and directing more of the research effort to the northern canadian cordillera

holocene glacier history of frank mackie glacier northern british columbia coast mountains frank mackie glacier repeatedly advanced across the bowser river valley in northwestern british columbia to impound tide lake during the holocene the most recent infilling of tide lake was associa

stable carbon isotopes of carbonate pendants from chernozemic soils of saskatchewan canada carbonate pendants are almost pure pedogenic carbonate that formed in an environment that may contain lithogenic carbonates pendants were sampled from three chernozemic soils in saskatchewan a calcareous black soil of the oxbow association c3 vegetation dominant an orthic dark brown profile of the biggar association and a transect of four dark brown soils of the amulet association both with mixed c3 and c4 vegetation all the soils were developed from glacial deposits which contain 10 to 20 caco3 pedogenic carbonate is composed of minute crystals in layered clusters about 0 5 to 4 m in diameter lithogenic carbonate pebbles exhibit fine and close structured dolomite with large rhombohedral crystals the 13c values of the carbonate pendants in the oxbow soil reflect the range of the 13c values of the soil organic matter 25 0 to 26 0 with a relatively consistent fractionation factor of 16 5 more positive 13c values 4 0 to 6 9 from the biggar soil are consistent with the more positive 13c value of the soil organic matter as some of the organic matter is derived from blue grama a c4 grass with a 13c value of 16 0 more positive 13c values for the bk horizons of upper location in the orthic dark brown soils suggest a higher proportion of c4 plants today than in the past

pre little ice age glacier fluctuations in garibaldi provincial park coast mountains british columbia canada holocene glacier fluctuations prior to the little ice age in garibaldi provincial park in the british columbia coast mountains were reconstructed from geomorphic mapping and radiocarbon ages on 37 samples of growth position and detrital wood from glacier forefields glaciers in garibaldi park were smaller than at present in the early holocene although some evidence exists for minor short lived advances at this time the first well documented advance dates to 7700 7300 14c yr bp subsequent advances date to 6400 5100 4300 4100 2900 and 1600 1100 14c yr bp some glaciers approached their maximum holocene limits several times during the past 10 000 years periods of advance in garibaldi park are broadly synchronous with advances elsewhere in the canadian cordillera suggesting a common climatic cause the garibaldi park glacier record is also broadly synchronous with the record of holocene sunspot numbers supporting previous research that suggests solar activity may be an important climate forcing mec

little ice age proxy glacier mass balance records reconstructed from tree rings in the mt waddington area british columbia coast mountains canada the intention of this research was to explore whether dendroclimatological relationships could be used to reconstruct long term proxy records of little ice age glacier mass balance changes in the southern coast mountains of british columbia tree ring width chronologies from the mt waddington area were used in concert with historical glacier records to construct models spanning the past 450 years the approach was to build models that were based on derived relationships between tree ring growth and glacier mass balance 1 warmer temperatures in the summer positively influence tree growth but are detrimental to glacier health 2 colder temperatures during the winter and deeper snowpack have a negative impact on tree growth whereas they are related to greater accumulation on the glacier during the winter season stepwise regression analyses were applied to tree ring chronologies to predict glacier mass balance at local and regional scales the models of net annual balance for the region regional data set show that periods of positive mass balance occurred in the ad 1750s 1820s to 1830s and 1970s peaks of winter balance correspond closely to these periods showing a sharp drop in winter mass balance towards the end of the nineteenth century wavelet analyses suggest that glacial mass balance regimes in the region respond synchronously to pacific ocean circulation systems such as the el nino southern oscillation and the pacific decadal oscillation

holocene glacier activity in the british columbia coast mountains canada abstract the coast mountains flank the pacific ocean in western british columbia canada subdivided into the southern pacific ranges central kitimat ranges and northern boundary ranges the majority of large glaciers and icefields are located in the boundary and pacific ranges prior descriptions of the holocene glacial history of this region indicate the holocene was characterized by repeated episodes of ice expansion and retreat recent site specific investigations augment our understanding of the regional character and duration of these events in this paper previously reported and new radiocarbon evidence is integrated to provide an updated regional assessment the earliest evidence of glacier expansion in the coast mountains comes from the boundary ranges at 8 9 and 7 8 ka and in the pacific ranges at 8 5 8 2 ka with the latter advance corresponding to an interval of rapid global climate deterioration although generally warm and dry climates from 7 3 to 5 3 ka likely limited the size of glaciers in the region there is radiocarbon evidence for advances over the interval from 7 3 to 6 0 and at 5 4 5 3 ka in the pacific ranges following these advances glaciers in the pacific ranges expanded down valley at 4 8 4 6 4 4 4 0 3 5 2 6 1 4 1 2 and 0 8 0 4 ka while glaciers in boundary ranges were advancing at 4 1 4 0 3 7 3 4 3 1 2 8 2 3 1 7 1 1 and 0 8 0 4 ka after 0 4 ka it appears that most glaciers in the coast mountains continued to expand to attain their maximum holocene extents by the early 18th to late 19th centuries this enhanced record of holocene glacier activity highlights the temporal synchrony in the coast mountains individual expansion events in the mid to late holocene broadly correspond to intervals of regional glacier activity reported in the canadian rocky mountains in alaska and on high elevation volcanic peaks in washington state

little ice age glacial activity in strathcona provincial park vancouver island british columbia canada dendroglaciological and lichenometric techniques are used to establish the little ice age lia history of two glaciers colonel foster and septimus in strathcona provincial park vancouver island british columbia our lichenometric investigations were preceded by the development of a locally calibrated rhizocarpon geographicum growth curve 1708 1998 a d documentation of a 3 4 year ecesis interval for both trees and lichen greatly reduces one of the main uncertainties in using geobotanical methods for dating lia landforms the moraine dates provided therefore give a good approximation of the shift in climate conditions that lead to the retreat of the glaciers and subsequent moraine stabilization geobotanical evidence records three synchronous episodes of lia moraine deposition at both glaciers two prominent moraines at each site are dated to the early 1700s and late 1800s with a third smaller moraine dated to the mid 1930s moraines deposited prior to 1397 a d were also recorded at colonel foster glacier however precise dating of these moraines was not possible the moraine records from strathcona provincial park suggest two possible modes of glacier response i synchronous responses to larger scale climatic forcing and ii asynchronous responses to local factors such as microclimate topography and glacier geometry the vancouver island lia record was evaluated in the context of lia results from the pacific north american pna cordillera it compares well with regional moraine records from coastal british columbia washington alaska and the canadian rocky mountains suggesting a regional response of pna glaciers to climate change associated with the lia

pedogenic replacement of aluminosilicate grains by caco3 in ustollic haplargids south central montana u s a abstract a chronosequence of calcic soils formed on granitic glaciofluvial terrace deposits of rock creek and the clarks fork in south central montana shows progressive replacement of aluminosilicate parent material grains by calcium magnesium carbonate the terraces range from late pliocene to holocene in age as dated by tephrochronology correlation and stream incision rates replacement is first seen in soils that are as old as 120 000 yr the amount and degree of replacement increase in soils older than 120 000 yr along with the development of calcic horizons under the petrographic microscope carbonate replacement of quartz feldspars and the groundmass of andesite grains in rock creek soils is shown by embayed grains networks of carbonate along cracks and between parts of polycrystalline grains and optically aligned grain fragments within carbonate masses microprobe data suggest that silica is released by replacement because it is absent from carbonate filled spaces and is depleted in corrosion pits little microscopic evidence exists to support displacement of framework grains by carbonate because fragments of a single grain are rarely rotated out of optical alignment in the calcic soils of rock creek k fabric grains floating in a carbonate matrix may form by both replacement and displacement

neoglacial history of the coast mountains near bella coola british columbia the maximum holocene extent of glaciers in the study area is marked by late neoglacial little ice age terminal moraines moraine stratigraphy and 14c dates from a small number of sites suggest that glacier advance almost as extensive as that of the late neoglacial occurred about 2500 14c years bp and that late neoglacial advance began well before 770 14c years bp or the thirteenth century a d glacier termini then stood close to the position of the climax moraines for several centuries dates of stabilization of end moraines at 16 glaciers were determined by dendrochronology with tree ring counts corrected for sampling errors and ecesis most terminal moraines date from 1860 to 1900 many recessional moraines were formed between 1900 and 1940 coincident with a regionally documented phase of cooler and wetter climate the proposed chronology is similar to results from elsewhere in the canadian cordillera

alpine glaciers and permanent ice and snow patches in western canada approach their smallest sizes since the mid holocene consistent with global trends most alpine glaciers in the northern hemisphere reached their maximum extents of the holocene between ad 1600 and 1850 since the late 1800s however glaciers have thinned and retreated mainly be

expansion of alpine glaciers in pacific north america in the first millennium a d radiocarbon ages and lichen dated moraines from 17 glaciers in coastal and near coastal british columbia and alaska document a widespread glacier advance during the first millennium a d glaciers at several sites began advancing ca a d 200 300 based on radiocarbon dated overridden forests the advance is centered on a d 400 700 when glaciers along an 2000 km transect of the pacific north american cordillera overrode forests impounded lakes and deposited moraines the synchroneity of this glacier ad vance and inferred cooling over a large area suggest a regional climate forcing and to gether with other proxy evidence for late holocene environmental change during the me dieval warm period and little ice age provide support for millennial scale climate variability in the north pacific region

calendar dated early little ice age glacier advance at robson glacier british columbia canada dendrochronological studies at robson and bennington glaciers have provided the first calendar dating of an early little ice age glacier advance in north america dates derived from in situ stumps indicate that robson glacier began over riding forest between c ad 1142 and 1150 and continued until at least ad 1350 the highest rates of glacier advance c 3 8 m yr 1 occurred between ad 1214 and 1261 based on a series of kill dates from in situ stumps between c ad 1142 1214 and 1261 1350 rates were somewhat lower at c 2 2 5 m yr 1 this glacier advance terminated upvalley of the little ice age maximum position of robson glacier and there is no evidence at this site for glacial events between ad 1350 and 1783 however two smaller glaciers in the robson area and the main tongue of small river glacier have outermost little ice age moraines that date from the first decades of the ad 1700s all glaciers examined in the mount robson area have several well developed moraines dating from the period c

glacier fluctuations during the past 2000 years abstract a global compilation of glacier advances and retreats for the past two millennia grouped by 17 regions excluding antarctica highlights the nature of glacier fluctuations during the late holocene the dataset includes 275 time series of glacier fluctuations based on historical tree ring lake sediment radiocarbon and terrestrial cosmogenic nuclide data the most detailed and reliable series for individual glaciers and regional compilations are compared with summer temperature and when available winter precipitation reconstructions the most important parameters for glacier mass balance in many cases major glacier advances correlate with multi decadal periods of decreased summer temperature in a few cases such as in arctic alaska and western canada some glacier advances occurred during relatively warm wet times the timing and scale of glacier fluctuations over the past two millennia varies greatly from region to region however the number of glacier advances shows a clear pattern for the high mid and low latitudes and hence points to common forcing factors acting at the global scale globally during the first millennium ce glaciers were smaller than between the advances in 13th to early 20th centuries ce the precise extent of glacier retreat in the first millennium is not well defined however the most conservative estimates indicate that during the 1st and 2nd centuries in some regions glaciers were smaller than at the end of 20th early 21st centuries other periods of glacier retreat are identified regionally during the 5th and 8th centuries in the european alps in the 3rd 6th and 9th centuries in norway during the 10th 13th centuries in southern alaska and in the 18th century in spitsbergen however no single period of common global glacier retreat of centennial duration except for the past century has yet been identified in contrast the view that the little ice age was a period of global glacier expansion beginning in the 13th century or earlier and reaching a maximum in 17th 19th centuries is supported by our data the pattern of glacier variations in the past two millennia corresponds with cooling in reconstructed temperature records at the continental and hemispheric scales the number of glacier advances also broadly matches periods showing high volcanic activity and low solar irradiance over the past two millennia although the resolution of most glacier chronologies is not enough for robust statistical correlations glacier retreat in the past 100 150 years corresponds to the anthropogenic global temperature increase many questions concerning the relative strength of forcing factors that drove glacier variations in the past 2 ka still remain

the pendent calcretes in semi arid climates an example located near taforalt nw morocco abstract in temperate climates supergene carbonates often form beards or pendents on pebbles calcite crystallizations are known to develop according to a centripetal sequence from the void to the pebble and correspond to a cemented calcrete under the semi arid climate of ne morocco similar calcretes develop below pebbles however the concentration processes are different indeed the first acicular low mg calcite crystals appear at the point of contact with the lower face of the dolomitic pebbles and are mixed with discoi dal dolomite crystals towards the outside composite needles then lublinite and rhombohedrons are formed by successive crystallizations in the first formed needles the mg rate is subordinate to the rock composition calcite or dolomite then it becomes approximately constant except when palygorskite is noted the calcrete would develop centrifugally its carbonates would not come from external sources but would result from the pebble s weathering this process could be connected with calcareous epigenetic weathering

the little ice age in the canadian rockies abstract this paper reviews the evidence and history of glacier fluctuations during the little ice age lia in the canadian rockies episodes of synchronous glacier advance occurred in the 12th 13th early 18th and throughout the 19th centuries regional ice cover was probably greatest in the mid 19th century although in places the early 18th century advance was more extensive glaciers have lost over 25 of their area in the 20th century selective preservation of the glacier record furnishes an incomplete chronology of events through the 14th 17th centuries in contrast varve sequences provide continuous annually resolved records of sediments for at least the last millennium in some highly glacierized catchments such records have been used to infer glacier fluctuations evaluation of recent proxy climate reconstructions derived from tree rings provides independent evidence of climate fluctuations over the last millennium most regional glacier advances follow periods of reduced summer temperatures reconstructed from tree rings particularly ca 1190 1250 1280 1340 1690s and the 1800s reconstructed periods of higher precipitation at banff alberta since 1500 are 1515 1550 1585 1610 1660 1680 and the 1880s glacier advances in the early 1700s the late 1800s and in places the 1950 1970s reflect both increased precipitation and reduced summer temperatures negative glacier mass balances from 1976 to 1995 were caused by decreased winter balances the glacier fluctuation record does not contain a simple climate signal it is a complex response to several interacting factors that operate at different timescales evaluation of climate proxies over the last millennium indicates continuous variability at several superimposed timescales dominated by decade century patterns only the 19th century shows a long interval of sustained cold summers this suggests that simplistic concepts of climate over this period should be abandoned and replaced with more realistic records based on continuous proxy data series the use of the term lia should be restricted to describing a period of extended glacier cover rather than being used to define a period with specific climate conditions

neoglacial glacier fluctuations in the canadian rockies abstract the little ice age was the most extensive neoglacial glacier advance in the canadian rockies evidence of earlier less extensive neoglacial glacier advances is based on wood recovered from several glacier forefields wood flushed out of athabasca glacier 7550 8230 yr b p three dates and dome glacier 6120 6380 yr b p two dates indicates that forests occurred upvalley of present glacier termini during the hypsithermal detrital logs from peyto 14 dates saskatchewan 3 dates robson 3 dates and yoho 1 date glaciers plus in situ slumps at peyto and robson glaciers have yielded 14 c dates between 2490 and 3300 yr b p 12 dates between 2800 and 2990 this wood is derived from sources at or upvalley from present glacier termini and represents forests overridden by glaciers between ca 3100 and 2500 yr b p treeline was higher than present immediately prior to this advance this advance which did not extend beyond the little ice age maximum position is designated the peyto advance and correlated with the tiedemann advance in western british columbia earliest little ice age advances at peyto and robson glaciers are dated ca 800 600 yr b p at positions ca 500 m upvalley from little ice age limits

persistent millennial scale shifts in moisture regimes in western canada during the past six millennia inferences of past climatic conditions from a sedimentary record from big lake british columbia canada over the past 5 500 years show strong millennial scale patterns which oscillate between periods of wet and drier climatic conditions higher frequency decadal to centennial scale fluctuations also occur within the dominant millennial scale patterns these changes in climatic conditions are based on estimates of changes in lake depth and salinity inferred from diatom assemblages in a well dated sediment core after periods of relative stability abrupt shifts in diatom assemblages and inferred climatic conditions occur approximately every 1 220 years the correspondence of these shifts to millennial scale variations in records of glacial expansion recession and ice rafting events in the atlantic suggest that abrupt millennial scale shifts are important to understanding climatic variability in north america during the mid to late holocene unfortunately the spatial patterns and mechanisms behind these large and abrupt swings are poorly understood similar abrupt and prolonged changes in climatic conditions today could pose major societal challenges for many regions

early holocene glacier advance southern coast mountains british columbia canada abstract terrestrial and lake sediment records from several sites in the southern coast mountains british columbia provide evidence for an advance of alpine glaciers during the early holocene silty intervals within organic sediments recovered from two proglacial lakes are bracketed by ams 14 c dated terrestrial macrofossils and mazama tephra to 8780 6730 and 7940 6730 14 c yr bp 10 150 7510 and 8990 7510 cal yr bp radiocarbon ages ranging from 7720 to 7380 14 c yr bp 8630 8020 cal yr bp were obtained from detrital wood in recently deglaciated forefields of sphinx and sentinel glaciers these data together with previously published data from proglacial lakes in the canadian rockies imply that glaciers in western canada advanced during the early holocene the advance coincides with the well documented 8200 yr cold event identified in climate proxy data sets in the north atlantic region and elsewhere

late holocene glacial activity in manatee valley southern coast mountains british columbia canada the dendroglaciologic and lichenometric research methodologies employed in this study provide a perspective of glaciological conditions from 5 ka to present in a remote headwater area of the british columbia coast mountains since holocene ice fronts of four glaciers at this site periodically extended below treeline previous glacier advances overrode and buried forests beneath till deposits this study suggests that glaciers were expanding into standing forests at 4 76 and 3 78 ka following glacier expansion at 3 78 ka a period of recession ensued when glaciers withdrew upvalley long enough for the development of deep pedogenic surfaces and the growth of trees exceeding 300 years investigations at beluga and manatee glaciers benchmark a subsequent episode of significant glacial expansion at 2 42 ka referred to as the manatee advance this advance has regional correlatives and is distinguished from the tiedemann advance at manatee glacier by documentation of substantive ice front retreat between the

pedogenic carbonate cutans as a record of the holocene history of relic tundra steppes of the upper kolyma valley north eastern asia abstract pendant carbonate cutans on the undersides of coarse rock fragments in a steppe cryoarid soil profile on the steep south facing slope of the valley of the berelekh river in the upper kolyma valley north eastern asia provide a record of the holocene history of the tundra steppe ecosystem on the basis of two radiocarbon dates of cutan carbonate on stones at 40 100 cm depth a model of cutan growth was developed this suggests that the cutans have formed steadily from at least the early holocene until recent times and probably reflect the existence of a local area of stable tundra steppe vegetation throughout the holocene

a new regional residual separation for magnetic data sets using susceptibility from frequency domain electromagnetic data abstractregional residual separation is a fundamental processing step required before interpreting any magnetic anomaly data numerous methods have been devised to separate deep seated long wavelength regional anomalies from the near surface high frequency residual content such methods range in complexity from simple wavelength filtering to full 3d inversions but most procedures rely on the assumption that all long wavelength anomalies are associated with deep source bodies an incorrect assumption in some geologic environments we evaluated a new method for determining the contributions of near surface magnetic sources using frequency domain helicopter borne electromagnetic hfem data we inverted the in phase and quadrature components of the hfem data to produce an estimate of the spatial variation of magnetic susceptibility using this susceptibility information along with known topography and original survey flight path data we calculated a magnetic intensity grid by forward modeling there ar

late holocene glacier fluctuations in the wrangell mountains alaska four intervals of late holocene glacier advance are recognized from study of nine valley glaciers in the wrangell and westernmost st elias mountains of alaska the oldest glacial advance is recognized at the nabesna and barnard glaciers where five radiocarbon ages suggest advance as early as 2700 cal calibrated yr b p two additional radiocarbon dated advances are centered on cal yr a d 300 and the beginning of the little ice age about a d 1200 the best documented little ice age advances occurred during the mid 1600s through the 1800s and are recognized at all nine glaciers these latter advances are dated by tree rings of trees overrun by glaciers in five glacier valley by 17 radiocarbon dates and by tree ring and lichen ages from 20 moraines that were deposited during the culmination of these advances the glacial chronology is broadly similar to chronologies from adjoining alaskan mountain ranges at both coastal and interior sites for the past 3000 yr there are however differences in timing of advances during the first millennium a d the glacial history for the past 2000 yr is also consistent with temperature sensitive proxy records from interior alaska and yukon territory

late holocene environmental change at treeline in the northern coast mountains british columbia canada an integrated stratigraphic paleoecological and geochronological study of lake and fen sediments just beyond the terminus of berendon glacier provides insights into late holocene climate vegetation and glacier change in the northern coast mountains of british columbia cores collected from two small lakes in the foreland of berendon glacier and pits dug in a nearby fen record little lee age and older glacier advances the first little ice age advance in this area began more than 500 years ago and peaked in the early 17th century an earlier neoglacial advance began about 2800 3000 cal yr ago and may have lasted for hundreds of years there is also evidence for an intervening advance of even smaller magnitude around 1200 1300 cal yr ago the advances are broadly synchronous with those in other parts of western north america indicating that they were caused by regional possibly global changes in climate plant communities within the study area did not change dramatically during the late holocene the ranges of some plants however likely retracted or extended near treeline in response to changes in mean temperatures of perhaps 1 2degreesc as a well as changes in summer snow cover the greatest changes in vegetation occurred within and just beyond the forefields of berendon frank mackie and other nearby glaciers the largest climate shifts of the last 3000 years took place during the late little ice age and the last century climate warmed about 1 2degreesc during the 20th century accompanied by a rise in treeline an increase in coniferous tree cover in the subalpine zone and an increase in the temperature and biological productivity of ponds these trends are likely to continue if climate as expected continues to warm c 2004 elsevier ltd all rights reserved less

the properties genesis and environmental significance of calcitic pendents from the high arctic spitsbergen abstract calcitic pendents occurring beneath coarse clasts were investigated from a well drained profile near ny alesund spitsbergen developed on fluvio glacial deposits with a few carbonate rock fragments micromorphological study was combined with mineralogical geochemical and isotopic investigations to determine the relationships of calcitic pendent characteristics to soil conditions calcitic pendents are observed at all depths beneath clasts and display a succession of five types of laminae with strongly differentiated overall characteristics the number of laminae and their specific attributes are nearly unchanged with depth and with the petrographic nature of the host clast each lamina consists of weakly differentiated micro laminae that are grouped into six morphological facies precipitation of pedogenic carbonates is shown to be currently active throughout the profile induced by supersaturation of solutes with respect to calcite during the initial stage of freezing this process would form beneath clasts the calcitic pendents that are suggested to successively grow at all depths following the gradual progression of the frost front carbonate dissolution appears to mainly affect the fine soil mass from the surface down to the permafrost level controlled by summer biological activity differences of isotopic values of the whole calcitic pendents from those that would precipitate in equilibrium with present day soil conditions are explained by changes in soil conditions during the accretionary process 14 c values suggest that accretion of the pendents integrates phases which occurred during earlier episodes than the holocene the complex layering of calcitic pendents provides a sequential record of evolving soil forming conditions during a time period possibly longer than the last glacial cycle previous conditions are interpreted in relation to present conditions of precipitation the succession of micro laminae is thought to reflect minor climatic fluctuations and marked changes between adjacent laminae are thought to indicate significant climatic changes