investigating surface movements of debris covered miage glacier western italian alps using dendroglaciological analysis dendroglaciological analysis of supraglacial trees represents an example of applied dendro geomorphological methods in reconstructing glacier variations supraglacial trees react to glacier ice and debris movement assuming typical shapes with modified radial growth in this paper based on tree ring analysis of larix decidua mill we investigate the relationship between the distribution and growth of trees located on the most famous and representative debris covered glacier in the italian alps miage glacier valle d aosta and the superficial movements of ice and debris in the lower part of the tongue different growth anomalies e g pointer years compression wood abrupt growth changes were identified and dated three reference tree ring chronologies based on undisturbed larches growing outside the glacier were constructed for comparison with tree ring data from supraglacial trees the oldest sampled trees colonized the glacier surface just before 1960 the simultaneous presence of different disturbance indicators occurred mainly between 1984 and 1990 on the southern lobe and during the period 1989 93 on the northern glacier lobe these results fit with glaciological data documenting volume and surface level variations in the same period

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

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

ground zoning against seismic hazard in athens greece abstract the 1999 ms 5 9 athens earthquake caused serious structural damage to buildings in the western part of athens greece this paper presents the ground zoning against seismic hazard proposed shortly after the earthquake in order to aid reconstruction of the area existing engineering geological and geotechnical data were combined with local observations to provide a unified set of classification criteria consistent with provisions of the greek seismic code eak the accuracy and the possible limitations of this zoning procedure are addressed through comparison with observed damage distribution as well as results from seismic ground response analyses performed at sites with well established soil profiles there is clear evidence that the proposed zones correspond to geological formations exhibiting grossly different seismic response with regard to the design of common engineering structures however the mostly qualitative nature of the guidelines for ground categorisation provided by eak and the general lack of systematic site specific geotechnical data for the whole area induce uncertainties in the definition of the seismic design actions for the different zones these objective uncertainties certainly demand increased conservatism but do not limit application of the proposed methodology for first aid preliminary planning in the event of destructive earthquakes

tree ring based mass balance estimates for the past 300 years at peyto glacier alberta canada tree rings were used to reconstruct mass balance for peyto glacier in the canadian rocky mountains from a d 1673 to 1994 summer balance was reconstructed from tree ring estimates of summer temperature and precipitation in the canadian rockies winter balance was derived from tree ring data from sites bordering the gulf of alaska and in western british columbia the models for winter and summer balance each explain over 40 of the variance in the appropriate mass balance series over the period 1966 1994 the correlation between the reconstructed and measured net balances is 0 71 strong positive mass balances are reconstructed for 1695 1720 and 1810 1825 when higher winter precipitation coincided with reduced ablation periods of reconstructed positive mass balance precede construction of terminal moraines throughout the canadian rockies ca 1700 1725 and 1825 1850 positive mass balances in the period 1845 1880 also correspond to intervals of glacier readvance mass balances were generally negative between 1760 and 1805 from 1673 to 1883 the mean annual net balance was 70 mm water equivalent per year w e yr but it averaged 317 mm w e yr from 1884 to 1994 this reconstructed mass balance history provides a continuous record of glacier change that appears regionally representative and consistent with moraine and other proxy climate records

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

teleconnections in the geopotential height field during the northern hemisphere winter abstract contemporaneous correlations between geopotential heights on a given pressure surface at widely separated points on earth referred to as teleconnections in this paper are studied in an attempt to identify and document recurrent spatial patterns which might be indicative of standing oscillations in the planetary waves during the northern hemisphere winter with time scales on the order of a month or longer a review of existing literature on the subject reveals the existence of at least four such patterns the north atlantic and north pacific oscillations identified by walker and bliss 1932 a zonally symmetric seesaw between sea level pressures in polar and temperature latitudes first noted by lorenz 1951 and what we will refer to as the pacific north american pattern which has been known to operational long range forecasters in this country since the 1950 s a data set consisting of nmc monthly mean sea level pressure and 500 mb height analyses for a 15 year period is used as a basis fo

a high resolution reconstruction of storglaciaren mass balance back to 1780 81 using tree ring data and circulation indices storglaciaren in northernmost sweden has the world s longest ongoing continuous mass balance record starting in 1946 to extend this massbalance record we have reconstructed summer bs and winter bw mass balances separately back to the mass balance year 1780 81 with annual resolution we used tree ring data for bs and a set of circulation indices based on the sea level pressure for bw both proxies have correlation coefficients with respective mass balance components of ca 0 7 the reconstructed net balance bn of storglaciaren was well correlated to the observations during 1946 1980 r 0 8 p 0 05 our reconstruction agrees well with previously obtained results of northern sweden glacier variability where the predominantly positive bn years between 1890 and 1910 correspond to the well documented post little ice age advance of storglaciaren furthermore the results suggest that bs as a function of summer temperatures is more important than bw in determining the bn which is contrary to glaciers in the maritime parts of western scandinavia in general bn has been negative over the last 220 yr suggesting a predomination of continental conditions over northern sweden however the influence of bw increased in the late twentieth century indicating a shift to a more oceanic climate regime

glacier change in northern sweden from ad 500 a simple geometric model of storglaciaren a simple geometric model of glacier volume is derived the model is based on the assumption that the net mass balance averaged over the glacier surface is related to the summer temperature and winter accumulation at a representative height on the glacier this height varies with time as climate changes in ways that are determined by the geometry of the glacier surface expressions are derived for the equilibrium glacier volume v eq as a function of summer temperature and winter accumulation and for the glacier response time as a function of volume the model is used to reconstruct the volume of storglaciaren over the period ad 500 1992 measured net mass balance data for storglaciren 1946 92 are used to estimate the model parameters for the summer temperature forcing the long treering based temperature reconstruction for northern fennoscandia is used to extend a temperature record near the glacier back to ad 500 for the past accumulation forcing a range of assumptions is tested the results show that the prime cause of the decrease in volume of storglaciaren between 1946 and 1992 was relatively low accumulation over 1946 89 as opposed to warm temperatures as previously supposed reconstructed volume changes agree well with geomorphological evidence where differences occur deductions can be made about past accumulation for example the maximum reconstructed glacier volume is associated with the cold period from 1580 to 1740 but relatively low accumulation probably limited the volume to values not much larger than that achieved around 1916

relationships between synoptic scale atmospheric circulation and glacier mass balance in south western canada during the international hydrological decade 1965 74 on recherche la correlation entre la circulation atmospherique a l echelle synoptique et le bilan glaciaire dans la cordillere du sud ouest canada des techniques de caracterisation synoptiques objectives sont appliquees a des donnees glacio meteorologiques provenant du peyto glacier en alberta et sentinel glacier en colombie britannique et a des releves climatologiques emanant des stations meteorologiques voisines au niveau de 500 mbar on a analyse et compare deux echelles de cartes meteorologiques synoptiques l une est plus petite avec de nombreuses fluctuations l autre est plus grande avec des traits plus generaux

tree ring based reconstructions of north american glacier mass balance through the little ice age contemporary warming transition abstract glacier mass balance reconstructions provide a means of placing relatively short observational records into a longer term context in western north america mass balance records span four to five decades and capture a relatively narrow window of glacial behavior over an interval that was dominated by warming and ablation we use temperature and moisture sensitive tree ring series to reconstruct annual mass balance for six glaciers in the pacific northwest and alaska mass balance models rely on the climatic sensitivity of tree ring chronologies and teleconnection patterns in the north pacific the reconstructions extend through the mid to latter portions of the little ice age lia and explore the role of climate variability in forcing mass balance across multiple environmental gradients synchronous positive mass balance intervals coincide with regional moraine building and solar minima whereas differences in lia glacier behavior are related to synoptic climate forcing secular warming in the late 19th century to present corresponds with the only multi decadal intervals of negative mass balance in all glacier reconstructions this suggests that contemporary retreat in western north america is unique with respect to the last several centuries and that regional patterns of glacier variability are now dominated by global climate forcing

dendrohydroclimate reconstructions of july august runoff for two nival regime rivers in west central british columbia lengthy records of river discharge are necessary to comprehensively assess the long term connection between synoptic climate forcings and nival regime systems in british columbia a regional multispecies network of tree ring width and ring density chronologies was built for west central british columbia with the intention of dendrohydrologically extending short runoff records in this area extended records of july august mean discharge anomalies for the skeena and atnarko rivers were reconstructed back to ad 1660 low flow events represented during the late 1600s early 1700s and late 1800s lie beyond those experienced during the recent instrumental period for these basins the documentation of extreme events of this magnitude necessitates consideration when planning for future water resources in this region supplementary dendroclimatic reconstructions of the winter pacific north american pna pressure anomaly pattern and records of mean summer temperature and end of winter snow water equivalent were also constructed these ancillary climate records provide insight into the long term climate drivers of annual discharge dynamics within these nival basins correlation and wavelet analyses confirm the persistent relationship of synoptic climate regimes described by the southern oscillation index nino 3 4 pacific decadal oscillation and pna indices on runoff in west central british columbia copyright 2012 john wiley sons ltd

proxy data reconstructions of the storglaciaren sweden mass balance record back to ad 1500 on annual to decadal timescales regional summer temperatures t s derived from tree rings and large scale atmospheric circulation indices north atlantic oscillation nao were used to infer the mass balance of storglaciaren sweden on annual and decadal timescales back to ad 1500 winter january march nao was not a suitable proxy for interannual winter balance variability but seemed to have substantial influence on decadal timescales t s were highly correlated to the summer balance but also to the annual net balance this association was much weaker on decadal timescales mainly because of the increased maritime climate around 1980 storglaciaren net balance was modelled back to ad 1500 with annual resolution using t s as a predictor and ad 1664 with decadal resolution using t s and nao as predictors both reconstructions displayed similar evolution negative mass balances dominated most of the 16th century followed by a longer period of predominantly positive mass balance years culminating in about 1750 this is in agreement with previous suggestions of holocene maximum expansion of storglaciaren at that time subsequently the mass balance is highly variable with an increased number of negative years the build up to the well documented early 20th century advance is evident as mass balance becomes progressively more positive towards the early 20th century

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

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

glacier change in western north america influences on hydrology geomorphic hazards and water quality the glaciers of western canada and the conterminous united states have dominantly retreated since the end of the little ice age lia in the nineteenth century although average rates of retreat varied from strong in the first half of the twentieth century with glaciers stabilizing or even advancing until 1980 and then resuming consistent recession this retreat has been accompanied by statistically detectable declines in late summer streamflow from glacier fed catchments over much of the study area although there is some geographical variation over recent decades glaciers in northwest bc and southwest yukon have lost mass dominantly by thinning with relatively low rates of terminal retreat and glacier fed streams in that region have experienced increasing flows in many valleys glacier retreat has produced geomorphic hazards including outburst floods from moraine dammed lakes mass failures from oversteepened valley walls and debris flows generated on moraines in addition to these hydrologic and geomorphic changes evidence is presented that glacier retreat will result in higher stream temperatures possibly transient increases in suspended sediment fluxes and concentrations and changes in water chemistry with climate projected to continue warming over the twenty first century current trends in hydrology geomorphology and water quality should continue with a range of implications for water resources availability and management and hydroecology particularly for cool and cold water species such as salmonids copyright 2008 john wiley sons ltd

a tree ring based record of annual mass balance changes for the ts tuyuksuyskiy glacier and its linkages to climate change in the tianshan mountains abstract fluctuations in glacier mass and volume are indicative of changes in the climate system they also strongly affect regional climate and hydrology in this paper we explore possible relationships between the radial growth of schrenk spruce picea schrenkiana fisch et mey and the mass balance of the tsentralniy tuyuksuyskiy ts tuyuksuyskiy glacier which is located on the northern slopes of the tianshan mountains in arid central asia we attempt to reconstruct the historical mass balance variability of the ts tuyuksuyskiy glacier using tree ring widths and stable carbon isotope chronologies the reconstruction is able to explain 62 1 of the variance in the annual glacier mass balance record over the 1965 2014 calibration period we also analyzed centennial mass balance variability and its linkages to climate change the ts tuyuksuyskiy glacier has a negative annual mass balance in most years and since 1968 has undergone the most rapid and longest melting process in the past 166 years the mass balance change of the glacier is controlled by the combination of temperature and precipitation conditions this study could be useful for more detailed glaciological hydrological and climatological assessments in this portion of the tianshan mountains

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

accurate surface exposure dating with lichens lichenometry accurately dates exposure times of glacial moraines and landslides when measuring the longest axis of the largest crustose lichen on many blocks as demonstrated by numerous examples in sweden the sizes of rhizocarpon subgenus rhizocarpon describe five pulses of glacial moraine creation in 120 yr six historic california earthquakes between ad 1800 and 1906 caused many landslides that constrain lichen growth as linear with a dating accuracy of 0 5 yr crustose lichen sizes date earthquake created additions to sierra nevada talus with an accuracy of 5 yr the oldest lichen ages are 400 yr for lecanora sierrae 800 yr for lecidea atrobrunnea and 1100 yr for acarospora chlorophana and rhizocarpon subgenus rhizocarpon lichen sizes also record differing spatial attenuation of ground shaking from the magnitude m w 7 9 san andreas earthquake of ad 1857 and the more distant smaller san jacinto ad 1800 earthquake which both caused sierra nevada rockfalls ad 1800 seismic shaking was relatively stronger than that of ad 1857 farther north perhaps expressing stronger love and rayleigh styles of surface waves from the north trending ad 1800 surface rupture that were particularly efficient in causing rockfalls at greater distances

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

variations in the building site categories in the underground mining region of doubrava czech republic for land use planning abstract in terms of demands and needs of ground investigation and foundation engineering the engineering geological conditions in the underground mining territories represent anthropogenically influenced areas in the most complicated manner since they suffer the impacts from the underground mining of mineral resources the subjects of observation are the so called building site categories which represent a certain risk factor that must be taken into consideration during foundation engineering and engineering geological studies in the undermined territories it is necessary to realise that underground mining is an anthropogenic geodynamic process which significantly varies over time due to mining change and consequently with variations in the position shape and size of subsidence in a subsidence basin all the above mentioned variations should be mandatory knowledge for land use planners engineering geologists geotechnicians foundation engineers and designers because of the evident logicality of these needs this work presents a case study ostrava karvina coal district in the north east of the czech republic of variations in the building site categories over time and the results show that the chronology of the changes has a very significant influence in this area of interest the results of the building site category evaluation imply that the majority of the interest area falls within relatively good conditions for founding all kinds of structures however it was then necessary to consider variations over time in the surface area of less suitable building site categories a trend certainly confirmed the existence of the previously presumed mutual relationship between building site categories and subsidence size distribution it is apparent from the analytic results of the relationship between building site categories and planned development that the negative impacts of mining have been only partly considered or completely disregarded in the development planning process consequently future land use planners should carefully consider these particular building site categories as the most important and significant factors in the undermining of a region in this manner development can be successfully planned for present and future safety

tree ring derived little ice age temperature trends from the central british columbia coast mountains canada abstract most glaciers in the british columbia coast mountains reached their maximum holocene extent during the little ice age early and late little ice age intervals of expansion and retreat fluctuations describe a mass balance response to changing climates although existing dendroclimatic records provide insights into these climatic fluctuations over the last 400 yr their short durations prohibit evaluation of early little ice age climate variability to extend the duration of these records submerged coarse woody debris salvaged from a high elevation lake was cross dated to living chronologies the resulting chronology provides the opportunity to reconstruct a regional june july air temperature anomaly record extending from ad 1225 to 2010 the reconstruction shows that the intervals ad 1350 1420 1475 1550 1625 1700 and 1830 1940 characterized distinct periods of below average june july temperature followed by periods of above average temperature our reconstruction provides the first annually resolved insights into high elevation climates spanning the little ice age in this region and indicates that little ice age moraine stabilization corresponds to persistent intervals of warmer than average temperatures we conclude that coarse woody debris submerged in high elevation lakes has considerable potential for developing lengthy proxy climate records and we recommend that researchers focus attention on this largely ignored paleoclimatic archive

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

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

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

toward a late holocene glacial chronology for the eastern nyainqentanglha range southeastern tibet abstract monsoonal affected temperate glaciers in the eastern nyainqentanglha range southeastern tibet are highly sensitive to climate change knowledge about their late holocene dynamics is still however widely lacking the few studies on glacial chronology which are available for this region tend to mainly focus on dating results without sufficiently considering the geomorphological setting often leading to misinterpretations in this complex high mountain environment in this study two selected glacier forelands are investigated using a multi proxy approach encompassing detailed geomorphological mapping dendrochronology sedimentology and optically stimulated luminescence as well as radiocarbon dating the starting point was the creation of a consistent morphosequence which was validated by remote sensing of further glacier forelands from the wider region similarities and differences between the investigated settings were analyzed in detail to identify the relevant morphological and topoclimatic forcing mechanisms we found evidence of climatic events affecting the whole region during the little ice age resulting in similar configurations and numbers of moraines the geomorphological settings of the glacier forelands are however remarkably different making investigations of the landform and sediment configuration an indispensable condition for their interpretation subsequently constraints from different methods of relative and numerical dating were evaluated critically and included into a conceptual chronosequence if applicable our results suggest that the late holocene maximum glacier advance comprised several successive advances from mid 17th to mid 18th century none of our observations supports an earlier neoglacial advance reaching further than the lia maximum after the lia maximum continued retreat that was only interrupted by short phases of stability followed as evidenced by 2 3 recessional moraines in the investigated settings

reconstruction of climate and glacial history based on a comparison of varve and tree ring records from mirror lake northwest territories canada abstract this study compared the hydroclimatic signals recorded in annually laminated varved sediments and tree rings within a small study area in the selwyn mountains of the southwestern northwest territories southeastern yukon territory border region of canada the records were located immediately adjacent to each other and within 6 km of instrumental meteorological and hydrometric records which permitted a detailed analysis of climate in the area from ad 1704 to 1996 this study explored the challenges of annually resolved multi proxy hydroclimate analyses and examined how best to interpret the climate record given the differences in proxy formation and the respective signals the high frequency annual variability from both proxies showed a good match for some parts of the record e g mid 1700s and much of the 1900s but revealed different sensitivities at other times e g 1800s however both records contained a common low frequency decadal summer climate signal glacier dynamics influenced varve formation through altered sediment availability during the inferred little ice age lia maximum ice stand in the catchment from ad 1778 to 1892 and subsequent recession after this maximum as a result of reduced lia sedimentation july mean temperatures reconstructed from varve thickness during the 1800s were underestimated compared to the tree ring estimates other instances of low frequency divergence were apparent particularly during parts of the twentieth century despite the overall similarities the extended varve record also provided a glacial history for the southern selwyn mountains indicating probable glacier advances during ad 1300 1450 and ad 1600 1670 maximum ice stand during the 1800s followed by twentieth century recession

extending the place glacier mass balance record to ad 1585 using tree rings and wood density abstract recognizing that climate influences both annual tree ring growth and glacier mass balance changes in the mass balance of place glacier british columbia were documented from increment core records annually resolved ring width rw maximum mxd and mean density md chronologies were developed from engelmann spruce and douglas fir trees sampled at sites within the surrounding region a snowpack record dating to ad 1730 was reconstructed using a multivariate regression of spruce md and fir rw chronologies spruce mxd and rw chronologies were used to reconstruct winter mass balance bw for place glacier to ad 1585 summer mass balance bs was reconstructed using the rw chronology from spruce and net balance was calculated from bw and bs the reconstructions provide insight into the changes that snowpack and mass balance have undergone in the last 400 years as well as identifying relationships to air temperature and circulation indices in southern british columbia these changes are consistent with other regional mass balance reconstructions and indicate that the persistent weather systems characterizing large scale climate forcing mechanisms play a significant glaciological role in this region a comparison to dated moraine surfaces in the surrounding region substantiates that the mass balance shifts recorded in the proxy data are evident in the response of glaciers throughout the region

time scale for adjustment of glaciers to changes in mass balance the length of time tm over which a glacier responds to a prior change in climate is investigated with reference to the linearized theory of kinematic waves and to results from numerical models we show the following tm may in general be estimated by a volume time scale describing the time required for a step change in mass balance to supply the volume difference between the initial and final steady states the factor f in the classical estimate of m l u where i is glacier length and u is terminus velocity has a simple geometrical interpretation ft is the ratio of thickness change averaged over the full length i to the change at the terminus although both u and f relate to dynamic processes local to the terminus zone the ratio f u and therefore tm are insensitive to details of the terminus dynamics in contrast to conclusions derived from some simplified kinematic wave models a more robust estimate of tm independent of terminus dynamics is given by tm h b where h is a thickness scale for the glacier and b is the mass balance rate negative at the terminus we suggest that tm for mountain glaciers can be substantially less than the 1o2 103 years commonly considered to be theoretically expected

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

holocene history of hubbard glacier in yakutat bay and russell fiord southern alaska stratigraphic and geomorphic data defined by radiocarbon ages tree ring dates and historical observations provide evidence of three major holocene expansions of hubbard glacier early in each advance the hubbard glacier margin blocked russell fiord to create russell lake raising base level and causing stream beds and fan deltas throughout the russell drainage basin to aggrade each hubbard glacier expansion continued with an ice lobe advancing through disenchantment and yakutat bays in the west and an eastern lobe advancing into russell fiord the earlier two holocene expansions were respectively under way at 7690 and 5600 calibrated yr b p and each advance culminated more than 1 k y later the late holocene advance was under way by 3100 yr ago and reached 13 km farther south in russell fiord than the preceding two expansions late holocene deglaciation of yakutat and disenchantment bays was complete before a d 1791 nunatak glacier flowing from neves east of russell fiord became the primary ice source to the russell fiord lobe at or before this date ice retreat from the southern end of russell fiord began in the late eighteenth century and the penultimate russell lake drained ca a d 1860 the relatively slow advances and more rapid retreats of hubbard glacier are consistent with the model of the iceberg calving glacier cycle hubbard glacier is currently advancing and will likely reestablish russell lake in the near future affecting local fisheries however glacier lobes are unlikely to reach the area of the town of yakutat built on late holocene glacial deposits in the next 1 k y

sadiola hill a world class carbonate hosted gold deposit in mali west africa the 8 moz sadiola hill gold deposit is located in the kedougou kenieba inlier a window of deformed ca 2200 to 2050 ma rocks that crop out in eastern senegal and western mali the geology of the inlier differs from other paleoproterozoic granite greenstone belts and sedimentary basins by the abundance of carbonate rocks the sadiola hill gold deposit occurs within 3 km of the senegal mali shear zone and country rocks in the region have undergone polycyclic deformation the lithostratigraphy of the open pit consists of impure limestones overlain by younger sequences of detrital sedimentary rocks which include arenite wacke and siltstone the sedimentary rocks have been subjected to regional greenschist facies metamorphism and have been intruded by multiple generations of synkinematic calc alkaline stocks and dikes the bulk of the ore is hosted within a n s to nnw trending 10 to 50 m wide brittle ductile dilational shear zone defined as the sadiola shear zone gold lodes also occur along an array of steep nne trending shear zones geometric and kinematic analyses indicate that the ore hosting structures were undergoing sinistral displacement at the time of mineralization locally defined as the d3s nnw sse shortening event hydrothermal alteration is polyphase and includes an early high temperature calc silicate phase i e porphyroblastic growth of actinolite tremolite followed by a potassic phase i e biotite calcite quartz k feldspar tourmaline actinolite that was synchronous with ore mineral deposition paragenetic studies reveal a multistage ore development that includes an as rich sulfide stage followed by an au sb stage the ore is associated with a metal enrichment suite of au as sb cu fe w mo ag bi zn pb te the sadiola hill deposit shares a similar relative timing and structural setting to that of other world class orogenic gold systems in the west african craton e g ashanti loulo with gold deposition occurring during a period of transcurrent tectonics after the cessation of region wide compressional deformation the high temperature paragenesis at sadiola hill is atypical of gold mineralization in the craton and indicates that the late eburnean tectono magmatic activity between ca 2080 and 2060 ma played an important role in the dynamics of hydrothermal fluid circulation along the senegal mali shear zone