a record of post glacial moraine deposition and tephra stratigraphy from otokomi lake rose basin glacier national park montana the sedimentary record of otokomi lake glacier national park montana was studied to determine the age of an adjacent crowfoot moraine the presence of mt st helens jy ash near the bottom of the longest percussion core limits drainage basin deglaciation to before 11 400 14c years before present bp although 14 100 bp is the estimated basal age of the core correlative shifts in loss on ignition coarse 1 mm grain size magnetic susceptibility and x ray gray scale data at a depth of 185 cm are interpreted to be related to a sedimentary change in otokomi lake brought about by the deposition of the adjacent crowfoot moraine the estimated age of the moraine is 10 590 bp which is within the younger dryas interval this information supports the hypothesis that crowfoot moraines represent a regional western north american response to younger dryas cooling

the variation of temperature with time and hydrocarbon maturation in sedimentary basins formed by extension abstract when a sedimentary basin is formed by extension both the subsidence history and the temperature gradient can be calculated hence the time temperature history of any stratum can be obtained three types of behaviour occur the temperature of material which never reaches depths greater than about 4 km increases at all times the time temperature history of material which finally sinks to greater depths reaches a maximum during the subsidence history the time at which this maximum occurs decreases as the depth increases at greater depths the maximum temperature occurs at the time the basin is formed the time temperature history is then used to calculate lopatin s maturation index for each stratum as a function of time and the index plotted as a function of depth and time for different amounts of extension the maximum temperature at a given depth and hence lopatin s index is almost independent of the amount of extension when the age of the basin is greater than about 150 ma similar calculations taking account of sediment compaction show the same behaviour though the maturity of the material at a given depth is increased because both lopatin s index and its calibration are empirical it is important to develop new maturation indices based on individual molecular reactions whose activation energies can be determined in the laboratory

late holocene light ring chronologies from subfossil black spruce stems in mires of subarctic quebec subfossil black spruce picea mariana mill b s p stems from permafrost mires in a 250 km2 area at the arctic tree line near the eastern coast of hudson bay were sampled for the construction of a long light ring chronology spanning the late holocene thirty three out of the 143 sampled spruce logs were 14c dated yielding dates between 4580 and 1540 bp 3550 3010 cal bc cal ad 377 649 light rings rings with thin walled latewood cells or showing reduced latewood cell development were numerous in all the studied stem discs and a set of 47 logs was successfully cross dated the cross dated trees were used to build seven floating light ring chronologies located between c 1200 cal bc and cal ad 500 i e c 1200 to 1000 cal bc 900 to 800 cal bc 700 to 400 cal bc 700 to 500 cal bc 100 cal bc to cal ad 300 cal ad 50 to 450 and cal ad 400 to 500 the large number of light rings in mire spruces appears to be associated with particular growth conditions in mires a comparison of

8000 year old wood from the athabasca glacier alberta several wood fragments of pinus sp dated at 8230 80 and 8000 90 years bp and abies sp were recovered from the snout of the athabasca glacier this wood derived from an unknown source up valley indicates that the glacier was less extensive than at present during the hypsithermal and that an area up valley of the present snout was tree covered ca 8000 8300 years bp

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

holocene vegetational history of the kootenai river valley montana abstract pollen records in the kootenai and fisher river drainages in western montana reveal a fivezone sequence of holocene vegetation change deposition of glacier peak ash layer g ca 10 540 660 yr b p in the lowermost sediments clay intermixed with pebbles at tepee lake gives a minimum date for the initiation of sedimentation initial vegetation on the newly deglaciated terrain was dominated by pinus probably white bark pine with small amounts of gramineae picea and abies reflecting a relatively cool moist macroclimate two vegetation units appear to contribute to pollen zone ii ca 11 000 7100 yr b p arboreal communities with pines along with pseudotsuga or larix or both and treeless vegetation dominated by artemisia pollen zone ii represents an overall warmer macroclimate than occurred upon ice withdrawal after ca 7100 yr b p pollen zone iii diploxylon pines became a major pollen contributor near both tepee lake and mckillop creek pond indicating an expansion of xerophytic forest p contorta and p ponderosa along with an increase in the prominence of pseudotsuga menziesii or larix occidentalis or both artemisia briefly expanded coverage near tepee lake concomitant with the mazama ashfall ca 6700 yr b p a short term climatic trend with more available water began after ca 4000 yr b p as abies probably a grandis along with picea engelmannii became a more regular component of the forest surrounding both sites emergence of the modern macroclimate is indicated primarily with the first regular appearance of tsuga heterophylla in the pollen record by ca 2700 yr b p synchronous with the development of western hemlock forest within the same latitudes in northern idaho and northeastern washington

oxygen isotope ratios from tree rings containing compression wood abstract oxygen isotope determinations on the cellulose of tree rings cut from two leaning picea engelmannii revealed significant differences between results from normal and compression wood radii nine samples 10 year periods from the normal wood radius 1721 1953 in one tree showed good agreement with proxy climate information and maximum differences of 1 8 between the warmest and coolest decades sampled differences of equivalent magnitude were found between samples from the same decade from normal and compression wood radii these differences are strongly related to the amount and or density of compression wood present and suggest that sampling for paleoclimatic work should be restricted to complacent erect trees without compression wood rings

postglacial history of subalpine forests olympic peninsula washington usa to investigate subalpine vegetation history on the olympic peninsula washington usa two pol len macrofossil and charcoal records were studied in climatically distinct zones martins lake 1415 m in the moist tsuga mertensianazone and moose lake 1508 m in the drier abies lasiocarpa zone the interpret ation of fossil pollen assemblages was aided by comparisons with 308 modern assemblages from the olympic peninsula and western north america both pollen records show a cold dry period following deglaciation 10 000 radiocarbon years bp with sparse tundra and little similarity to any modern pollen assemblage in the early holocene when summer temperatures are thought to have been higher than present high percentages of alnus sinuata type pollen at both lakes suggest increased avalanche activity at martins lake warmer summers were not accompanied by forest establishment possibly because persistent spring snow pack snow avalanches and or edaphic constraints limited tree establishment at this site the martins lake record shows a steplike shift in vegetation to modern tsuga mertensiana abies amabilis parkland across the mazama tephra 6730 bp in contrast to martins lake abies lasiocarpa forest quickly established at moose lake in the early holocene though forests were probably initially open and fires may have been frequent from 7800 to 5100 bp forests near moose lake shifted gradually to cooler and moister species composition with the addition of chamaecyparis nootkatensis tsuga mertensianaand pinus though abies lasiocarpa remained dominant for est cover was probably greatest during this transition with parklike conditions at moose lake beginning at c 5100 bp the major differences in the records between the two sites may be due to differences in the local expression of regional climatic change and or differences in soil development and stabilization

olivine dolerite intrusionsin the fastnet basin sills of olivine microgabbro and olivine dolerite 0 5 180 m thick intrude lower liassic hettangian sinemurian sediments in the fastnet basin a sw extension of the n celtic sea basin about lat 50 n long 10 w the evidence of 3 wells and 2300 km of seismic reflection profiles indicates 6 major sills and sill complexes and 3 possible igneous centres or plugs a high level sill may intrude lower cretaceous sediments and one plug apparently deforms cretaceous reflectors k ar ages on separated biotites from a thick sill intruding liassic sediments gave 170 4 ma bajocian this sill contains 30 olivine fo 70 73 20 clinopyroxene magnesian salite 45 plagioclase an 60 78 with accessory magnetite ilmenite edenitic hornblende ti phlogopite apatite zircon spinel in olivine and sulphides alteration to serpentine minerals chlorite sericitic mica and leucoxene is sporadic the magmatism in the fastnet province thus appears to have been active from the mid jurassic to the early tertiary related initially to the time of initial rifting between the european and american plates and subsequently to their final separation between greenland and rockall and associated thulean magmatism

response of the columbia river fluvial system to holocene climatic change abstract an understanding of the response of a fluvial system to past climatic changes is useful for predicting its response to future shifts in temperature and precipitation to determine the response of the columbia river system to previous climatic conditions and transitions a well dated sequence of floodplain development in the wells reservoir region was compared with the paleoenvironmental history of the columbia river basin results of this comparison indicate that aggradation episodes occurring approximately 9000 8000 7000 6500 4400 3900 and 2400 1800 yr b p coincided with climatic transitions that share certain characteristics the inferred climates associated with aggradation had at least moderate rates of precipitation that occurred mainly in winter coupled with moderate winter temperatures such conditions would have resulted in the buildup of snowpacks and a high frequency of rain on snow events the warming and precipitation increases predicted for the pacific northwest under most co2 doubling scenarios are likely to repeat these conditions which could increase the frequency of severe sediment laden floods in the columbia river basin

organic microfossil geothermal alteration and interpretation of regional tectonic provinces optical analyses for colour transparency and reflectance of all organic fossils may be used for palaeotemperature data of the organic walled fossils acritarchs chitinozoans dinoflagellate cysts graptolites pollen and spores are of particular value in geothermometry at increasing temperatures fossil organic material shows progressive changes in colouration and increasing reflectance palaeotemperatures of sedimentary rocks may be derived from the optical characteristics of the main organic fossil groups recorded regional palaeotemperature values are associated with variations in overburden thickness and heat flow regional tectonic provinces typically record a restricted range of palaeotemperature values that may be related to sediment thickness and phases of igneous and tectonic activity

neoglacial history of robson glacier british columbia as glaciers in the canadian rockies recede glacier forefields continue to yield subfossil wood from sites overridden by these glaciers during the holocene robson glacier in british columbia forme

the holocene history of the columbia icefield canada abstract the columbia icefield is the largest icefield in the canadian rockies and feeds eight major glaciers that drain to three different oceans previous glacier studies have focused on athabasca and saskatchewan glaciers primarily due to their easy access this paper reviews evidence of the holocene history from all eight glaciers maximum holocene glacier extent was during the little ice age lia with dating based mainly on minimum tree ring estimates from trees growing on the moraines or from trees scarred tilted or killed by the glaciers the lia maximum advance was during the 19th century at athabasca 1843 4 dome 1846 saskatchewan 1862 and castleguard 1271 and detrital wood from lateral moraines at columbia ca 0 8 0 7ka two overridden stumps at columbia glacier indicate a previously unidentified advance ca 1500 a d these four phases of lia coincide with major reductions in summer temperatures reconstructed at the icefield there are also undated pre 1600 possibly pre lia moraines at kitchener glacier less extensive neoglacial glacier events are documented by an in situ forest bed buried by the saskatchewan glacier ca 2 90 3 4 ka equivalent to the peyto advance and stumps buried by till ca 4 2ka at boundary glacier detrital wood recovered from till at columbia glacier indicates at least one glacier advance ca 2 0 2 2ka till exposed between the bridge river and mazama tephras at stutfield glacier includes detrital wood dating 2 22 2 70 ka that possibly indicates a glacier advance immediately prior to the bridge river tephra regional paleoenvironmental data indicate warmer conditions and higher treelines in the early holocene detrital wood washed out of dome and athabasca glaciers indicates trees were present in these valleys ca 6 7 and 9ka upvalley of present glacier snouts evidence from castleguard cave indicates upstream entrances below the present icefield were probably ice free ca 9 5ka indicating the icefield was much reduced in extent at that time the detrital wood may represent wood killed and reworked by limited glacier advances from the icefield far upstream of present glacier fronts at these times

montane climate and vegetation dynamics in easternmost beringia during the late quaternary abstract new and published palynological data are used to investigate the quaternary vegetation history of high elevation sites in the mackenzie mountains of easternmost beringia northwest territories canada during some previous interglacials sites that are presently treeless supported spruce forest indicating conditions were warmer than present and possibly warmer than at any time in the holocene no information is available on vegetation in unglaciated portions of the mountains during the last glacial maximum but in the lateglacial ca 12 000 10 000 14 c yr bp a shrub and herb dominated vegetation characterized in the pollen record by artemisia betula salix gramnoids and herbs grew at all elevations and extended in a continuous corridor southwards to alberta populus balsamifera probably grew up to and above present treeline between about 11 000 and 9000 yr bp the late pleistocene vegetation of the mackenzie mountains contrasts with the rest of eastern and central beringia which supported a betula dominated shrub tundra by 12 000 yr bp betula shrub tundra expanded at all elevations in the mountains by 10 000 yr bp followed by the expansion of picea glauca and picea mariana forest at ca 8000 yr bp there is evidence for limited elevational shifts in treeline during the holocene picea population densities in the forest tundra were probably greater than at present in the early and mid holocene vegetation changes in the mackenzie mountains during this time are consistent with increased summer insolation and temperatures during the early to mid holocene higher resolution analysis decadal to century scale of small lake basins at treeline in this region also provide evidence for a late holocene increase in forest tundra density and or a treeline rise centered on 3000 yr bp slight warming at this time has been noted at sites in the southern rocky mountains and provides evidence for century scale climatic fluctuations superimposed on the longer term changes resulting from variations in insolation

the climate of north america and adjacent ocean waters ca 6 ka the climate of north america and the adjacent ocean at 6000 bp was estimated using five independent approaches using pollen data the terrestrial climate was estimated by the movement of ecozone boundaries and by the method of modern analogues both analyses indicate warmer temperatures in the western great lakes area and the northern great plains a model of sphagnum dominated peatland initiation when forced by canadian climate model 6 ka output projected a cooler and or wetter climate for continental western north america contrary to this a reconstruction of the distribution of sphagnum dominated peatlands in western canada indicates that they were located north of their modern distribution suggesting warmer and or drier conditions at 6000 bp this interpretation is strengthened by observations of lower lake levels at 6000 bp in western canada this drier climate may have been associated with warmer conditions as indicated by the quantitative climate reconstructions in general eastern north a

13c nuclear magnetic resonance studies of kerogen from cretaceous black shales thermally altered by basaltic intrusions and laboratory simulations cretaceous black shales from dsdp leg 41 site 368 in the eastern atlantic ocean were thermally altered during the miocene by an intrusive basalt the sediments overlying and underlying the intrusive body were subjected to high temperatures up to 500 c and as a result their kerogen was significantly altered the extent of this alteration has been determined by examination by means of 13c nuclear magnetic resonance using cross polarization magic angle spinning cp mas results indicate that the kerogen becomes progressively more aromatic in the vicinity of the intrusive body laboratory heating experiments simulating the thermal effects of the basaltic intrusion produced similar results on unaltered shale from the drill core the 13c cp mas results appear to provide a good measure of thermal alteration

midge inferred holocene climate history of two subalpine lakes in southern british columbia canada to investigate postglacial environmental changes in both the coastal and interior wet belts of british columbia fossil midges were analysed from two subalpine lakes one adjacent to the lower fraser canyon frozen lake and the other in mount revelstoke national park eagle lake the midge stratigraphy for frozen lake revealed an abundance of rheophilous chironomid taxa and simuliidae larvae refecting the presence of an inflowing stream an abundance of chaoborus mandibles and microtendipes during the early holocene c 10100 7700 14c years bp c 11500 8500 cal years bp suggests warmer temperatures a subsequent decline in the warm indicators and relative increases in cold stenotherms heterotrissocladius and diamesa indicate cooling until present day this climate reconstruction is consistent with other quantitative and qualitative evidence for past climatic change in southern british columbia at eagle lake the warm indicators dicrotendipes and polypedilum are seen in the early holocene c 85

postglacial vegetational history of tonquin pass british columbia a pollen and macrofossil study of peat sediments in tonquin pass british columbia provides the oldest dated record of vegetational and climatic changes in the middle canadian rockies paleoecological interpretation of these events dated by tephrochronology and radiocarbon dating is facilitated by comparisons with other regional pollen profiles late wisconsin ice receded from tonquin pass prior to 10 000 years bp by 9700 years bp a pinus contorta forest with an understory dominated by ferns had colonized the area the climate of this period was cool and moist following this interval was a brief episode 9000 8040 years bp of haploxylon pine dominance during which the climate became colder a long warm period beginning by 8040 years bp was characterized by desiccation of local meadows and fens and invasions of these areas by trees principally picea dated fossil picea and abies logs from alpine bogs within jasper national park document that timberlines had advanced beyond present limits by 8770 years b

multicomponent vsp imaging of tight gas sands low porosity bossier and cotton valley sands of the east texas basin u s have only a small acoustic impedance contrast with the encasing shales but a greater relative contrast in shear wave impedance vertical seismic profile vsp data acquired with both a near offset and far offset p wave source clearly demonstrate the p p reflectivity and p s mode conversions within the bossier section we designate conventional p wave reflectivity as p p shear wave reflectivity as s s and p wave shear wave mode conversion data as p s while bossier p p reflectivity is low it appears to be adequate for mapping thick sandbodies such as the york sandstone the main exploration target in this area however p p reflectivity is even lower and is inadequate for imaging the overlying cotton valley sands in contrast the far offset vsp data acquired with a p wave source demonstrate a high level of p s mode conversion which is used to image this interval with definition that is not provided by p p reflectivity this provides strong support for the use of p s mode conversion imaging for seismic characterization of tight sand reservoirs near offset shear wave vsp data acquired with a shearwave source show low s n ratio and limited bandwidth for the downgoing waveform because of the depth of the target shear wave energy appears to have a more limited range of propagation than p waves such effects may also have a strong negative impact on multicomponent imaging of these sands using surface seismic techniques multicomponent 3d vsp imaging provides a superior solution by placing the geophones closer to the subsurface zone of interest

a mid holocene record of vegetative change in central alberta sediments from three lakes in central alberta smallboy lake 53 35 n 114 8 w e i pond 53 38 n 112 51 w and hastings lake 53 25 n 112 53 w have been analyzed for their pollen content charcoal remains and in two lakes pyrite spherule concentration the earliest record radiometrically dated at 7400 years bp indicates the existence of mixed wood parkland vegetation by 5000 years bp the regional vegetation had a considerably more open structure than now and was subject to frequent fires presumably a response to the warm dry hypsithermal climate of this time the termination of the hypsithermal interval 4000 years bp is recorded in all three lakes by a marked increase in precipitation the onset of a cooler moister climatic regime stimulated forest closure and reduced regional fire activity although the local vegetation of each of the three study sites responded in a unique way to the changing climate by 3000 years bp the vegetation resembled the modern vegetation little change is re

postglacial palaeoecology of the subalpine forest grassland ecotone of southwestern alberta new insights on vegetation and climate change in the canadian rocky mountains and adjacent foothills postglacial vegetation change at the subalpine forest grassland ecotone in the foothills of southwestern alberta is reconstructed from fossil pollen plant macrofossils and fossil charcoal the fossils were obtained from the sediments of a small lake chronological control for the record is provided by tephra analysis and the 14c dating of terrestrial plant macrofossils the fossil record is compared with the results from similar studies at sites in the rocky mountains and foothills of alberta and british columbia the comparison of vegetation change at the upper and lower elevational limits of the subalpine forest provides a record of changes in temperature and aridity over the holocene at 10 000 yr b p the study site supported a shrub and herb dominated vegetation picea pinus abies forests were present at mid to high elevations in the mountains and in the northern foothills by this time the climate in the southern foothills was likely arid but not severely cold a relatively open picea and pinus forest was established in the study area between 9400 yr b p and 8000 yr b p fire activity in the region was at a postglacial maximum during this period the transition to forest suggests moister conditions by 8000 yr b p the importance of members of the chenopodiaceae amaranthaceae and typha latifolia increased suggesting an onset of arid conditions characterised by low and fluctuating water levels in lakes between 8000 yr b p and 5000 yr b p the picea and pinus contorta forest at the study site was largely replaced by grassland and pinus flexilis at high elevation sites treeline was located above its modern position during this period little vegetation change is recorded at sites in the northern foothills and at mid elevations at this time the vegetation change in the southern foothills and at high elevations suggests both an elevational and latitudinal displacement of vegetation zones during the mid holocene warm and arid conditions were prevalent in southwestern alberta picea glauca pinus contorta populus tremuloides forest has occupied the site since 5000 yr b p when cooler and moister conditions were established

evolution of the moose lake delta british columbia implications for holocene environmental change in the canadian rocky mountains abstract reconstruction of the geomorphic history of the moose lake delta is used to infer environmental change in the uppermost fraser river watershed british columbia delta top changes are interpreted from surface channel morphology riverbank exposures hand auger data vibracores and other borehole records river channel and overbank sediments are related to source area contributions in terms of granule lithology and fine

determinants of fire activity during the last 3500 yr at a wildland urban interface alberta canada abstract long term records of wildfires and their controlling factors are important sources of information for informing land management practices here dendrochronology and lake sediment analyses are used to develop a 3500 yr fire and vegetation history for a montane forest in jasper national park alberta canada the tree ring record ad 1771 2012 indicates that this region historically experienced a mixed severity fire regime and that effective fire suppression excluded widespread fire events from the study area during the 20th century a sediment core collected from little trefoil lake located near the jasper townsite is analyzed for subfossil pollen and macroscopic charcoal 150 m when comparing the tree ring record to the 3500 yr record of sediment derived fire events only high severity fires are represented in the charcoal record comparisons between the charcoal record and historical climate and pollen data indicate that climate and vegetation composition have been important controls on the fire regime for most of the last 3500 yr although fire frequency is presently within the historical range of variability the fire return interval of the last 150 yr is longer than expected given modern climate and vegetation conditions indicating that humans have become the main control on fire activity around little trefoil lake

holocene glacier fluctuations in the canadian cordillera alberta and british columbia abstract although the record of holocene glacier fluctuations in british columbia and alberta is still very fragmentary much recent progress has been made in their study dating of end moraines has been supplemented by studies of lateral moraine stratigraphy and dating of glacially overridden organic matter upstream of end moraines dates from sites close to contemporary glaciers indicate that ice had retreated to about its present limits before 10 ka bp prior to deposition of mazama tephra a minor pre hypsithermal readvance the crowfoot advance left deposits in the rockies and the interior of british columbia the earliest known neoglacial advances occurred 5 6 ka bp in the coast mountains and shortly after 4 ka bp in the rockies an advance culminating ca 4 3 ka bp has been reported from bugaboo glacier while evidence of another advance culminating in the period ca 2 5 1 8 ka bp the tiedemann advance is reported from more than one site following a recession the little ice age expansion the cavell advance began shortly after 900 bp this advance culminated in most cases in the 18th or 19th centuries the crowfoot tiedemann and little ice age advances were apparently of roughly the same magnitude the latter was most extensive in most cases but at several sites crowfoot moraines lie slightly farther downvalley than little ice age moraines during the present century ice fronts have generally retreated particularly rapidly in the period 1920 1950 a d although rates of retreat have decreased in the last three decades and some glaciers have readvanced slightly

late quaternary landscape history and archaeology in the ice free corridor some recent results from alberta abstract multidisciplinary research programs conducted within the alberta portion of the ice free corridor since 1986 as part of the archaeological survey s first albertans project have used studies of palaeogeography and palaeoenvironments to formulate archaeological search strategies this approach has resulted in the discovery of two new important sites saskatoon mountain ghqt 4 and the james pass meadow complex ekpu 3 to 9 that are yielding information on terminal late wisconsinan early holocene human occupation of the corridor both sites are dated by ams or conventional radiocarbon dates to the millennium 10 000 9 000 bp in the fifteen years since the 1978 amqua conference on the corridor other researchers have identified four additional significant paleo indian sites in this region so far none confirm human occupation of the ice free corridor region before about 11 000 bp

late quaternary paleoenvironments of the morley flats and kananaskis valley of southwestern alberta a 3 1 m section of limnic sediment and peat from a bog on the morley flats and a 2 8 m section of limnic sediment from wedge lake in the kananaskis valley have yielded the first comprehensive late quaternary biostratigraphic record from south western alberta both sections were analyzed for subfossil pollen molluscs and several sedimentary indices two distinct pollen zones were recognised the basal zone characterized by high relative abundancy of artemisia salix juniperus suggests that the morley flats were dominated by a sparse vegetation composed of aggressive pioneer species following deglaciation until prior to approximately 10 000 bp similarly the mollusc fauna from this zone is dominated by northern ranging species the second zone is typified by a predominance of pinus and picea this reflects the expansion of coniferous forest into the region both the relative abundance of southern ranging mollusc species and the total carbonate concentration in the sediment increase in this zone the veg

ostracod colour change by thermal alteration offshore ireland and western uk abstract ostracod colour changes from white to amber to red brown to black are principally interpreted to be the result of thermal alteration the changes in colour are thought to be caused by progressive carbon fixation of hydrocarbons derived from the surrounding sediments which invaded the ostracod shell exceptions to this scheme include faunas from organically poor limestones which remain white irrespective of the amount of heating and grey brown or yellow brown specimens coloured by the oxidation of diffuse pyrite thirty four exploration wells have been examined from the irish and western uk sectors and these have shown a progressive darkening of colours which is correlated with both burial depth and distance from igneous intrusions the fastnet basin and southern region of the north celtic sea exhibit higher colour change depth ratios to the porcupine basin and northern region of the north celtic sea basin implying greater palaeoheat flow in the former basins

abiotic versus biotic controls on the development of the fairmont hot springs carbonate deposit british columbia canada the relict fairmont hot springs deposit formed largely of carbonates covers an area of 0ae 5k m 2 and is up to 16 m thick the triangle shaped discharge apron which broadens down valley is divided into a proximal part with beds dipping at 10 and a distal part with beds dipping at 10 to 15 the deposit is formed of the 1 basal macrophyte 2 lower carbonate 3 middle clastic 4 upper carbonate and 5 upper clastic sequences two charcoal samples embedded in the lower carbonate sequence yielded dates of 8690 90 and 8270 70 cal yr bp indicating that much of the deposit formed post glacially during the early to mid holocene deposit aggradation ceased in the mid to late holocene when the fairmont creek valley was incised the lower and upper carbonate sequences which are the thickest sequences are composed of nearly equal parts of travertine abiotic and tufa biotic with feather dendrite travertine radiating dendrite travertine and stromatolite tufa dominating competition between calcite precipitation rates and biotic growth rates controlled the distribution of tufa and travertine across the discharge apron calcite and biotic growth rates were controlled largely by flow velocity across the apron which in turn was controlled by topography and regular fluctuations in spring water discharge volume during times of high spring discharge slow sheet flow over the proximal part of the apron promoted stromatolite growth whereas fast turbulent flow on the distal part of the apron induced rapid feather dendrite formation during times of low spring discharge quiescent shallow evaporative pools conducive to radiating dendrite formation formed on the proximal part of the apron whereas slow flow on the distal part promoted stromatolite growth facies with high calcite supersaturation experienced rapid abiotic dendrite growth that precluded most biotic growth

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

reconstruction of holocene changes in alpine vegetation and climate in the maligne range jasper national park alberta abstract pollen macrofossil logs and needles and oxygen isotope data from tree rings are presented for three alpine bog sites in the maligne range of the canadian rockies organic sedimentation at the watchtower site began prior to ca 9500 14 c yr b p and by 8770 yr b p timberlines were at least 100 m above present levels the two pollen records are dominated by pinus and subsequent changes in timberlines are inferred from pollen ratio data abies pinus and from macrofossils the recovered records indicate two periods of high hypsithermal timberlines ca 8800 7500 and 7200 5200 yr b p separated by a short interval ca 7300 7400 yr b p when timberline approached modern levels after ca 4500 yr b p timberlines have been similar to or lower than present reaching minimum values in the last 500 yr 18 o determinations from the cellulose of samples of 5 or 10 annual rings cut from contemporary picea englemannii at timberline show strong correlations with mean annual temperatures at jasper isotopic determinations from hypsithermal age logs recovered from sites above present timberline indicate mean annual temperatures were at least 0 5 c warmer ca 8060 and 8770 yr b p than at present at the watchtower site data from logs at the maligne pass site suggest that temperatures were about 1 2 and 1 6 c warmer ca 6000 and 5300 yr b p estimates of temperature from the pollen ratio data are more conservative and suggest maximum differences of ca 1 0 c in july temperatures over the last 8000 yr

a 9 c 2 d land seismic experiment for lithology estimation of a permian clastic reservoir the past 15 years have seen several successful applications of multicomponent seismic technology in hydrocarbon exploration many successes have been reported in the marine environment where statics and surface wave noise are less serious than on land nevertheless research into land multicomponent methods continues with many encouraging results

preferential soft tissue preservation in the hot creek carbonate spring deposit british columbia canada abstract the relict holocene hot creek carbonate spring deposit in southeast british columbia is characterized by excellent preservation of soft tissue organisms e g cyanobacteria but poor preservation of organisms with hard tissue e g wood diatoms the deposit is formed mainly of calcified cyanobacteria with fewer mineralized macrophytes plants bryophytes mosses wood and diatoms cyanobacteria grew as solitary filaments lyngbya and as radiating hemispherical colonies rivularia both were preserved by encrustation and encapsulation while alive and as casts after filament death and decay sheath impregnation was rare to absent filament encrustation whereby calcite crystals nucleated on and grew away from the sheath exterior produced moulds that replicated external filament morphology but hastened filament decay filament encapsulation whereby calcite nucleated in the vicinity of and grew towards the encapsulated filament promoted sheath preservation even after trichome decay subsequent calcite precipitation inside the hollow sheath generated sheath casts the inability of mineralizing spring water to penetrate durable cell walls meant that bryophytes macrophytes and most wood was preserved by encrustation some wood resisted complete decay for several thousand years and its lignified cell walls allowed rare permineralizations diatoms were not preserved in the relict deposit because the frustules were dissolved by the basic spring water amorphous calcium carbonate produced by photosynthetic co 2 removal may have acted as nucleation sites for physicochemically precipitated calcite thus metabolic activities of floral organisms probably initiated biotic mineralization but continuous inorganic calcite precipitation on and in flora ensured that soft tissues were preserved

latest pleistocene and early holocene fluctuations of glaciers in the canadian and northern american rockies in the canadian and northern american rockies small scale fluctuations of glaciers during and after late wisconsinan deglaciation have been identified using stratigraphy of superimposed glacial deposits geomorphology and records of glacial advance in lake and peat sediments several authors have proposed that valley glacier readvances of relatively modest scale followed the late wisconsinan maximum evidence for some of these is difficult to evaluate from the literature and no deposits recording such readvances have been numerically dated several minimum limiting radiocarbon dates for deglaciation suggest ice had retreated to within a few tens of km of present limits by ca 12 ka bp and to very near present limits by ca 11 ka bp one or more minor glacial advances or stillstands during recession evidently occurred in valley heads prior to 11 ka bp part of the evidence consists of moraines a few km downvalley from subsequently emplaced little ice age and crowfoot moraines the piper lake moraine in the mission mountains of montana is overlain by glacier peak g tephra and thus has a minimum age of 11 200 14c years bp the crowfoot advance a minor advance of about the same magnitude as little ice age advances occurred between ca 11 300 and 10 000 14c years bp and is thought to be related to the younger dryas climatic reversal crowfoot moraines have been found from jasper national park on the north to the mission mountains on the south crowfoot elas were an average of 40 m lower than modern elas around the canada u s border there have been past proposals of significant early holocene glacial advances in the rockies i e after crowfoot time but before the lia but recent evidence indicates that glaciers then were less extensive than at present

u th dating of lake sediments lessons from the 700 ka sediment record of lake junin peru abstract deep sediment cores from long lived lake basins are fundamental records of paleoenvironmental history but the power of these reconstructions has been often limited by poor age control uranium thorium u th dating has the potential to fill a gap in current geochronological tools available for such sediment archives we present our systematic approach to u th date carbonate rich sediments from the 100 m drill core from lake junin peru the results form the foundation of an age depth model spanning 700 kyrs high uranium concentrations 0 3 4 ppm of these sediments allow us to date smaller amounts of material giving us the opportunity to improve sample selection by avoiding detrital contamination the greatest factor limiting the success of previous u th dating efforts in other lake basins despite this advantage the dates from 174 analyses on 55 bulk carbonate samples reveal significant scatter that cannot be resolved with traditional isochrons suggesting that at least some of the sediments have not remained closed systems to understand the source of noise in the geochronological data we first apply threshold criteria that screen samples by their u th ratio reproducibility and 234 uinitial value we then compare these results with facies types trace element concentrations carbonate and total organic carbon content color reflectance mineralogy and ostracode shell color to investigate the causes of open system behavior alongside simulations of the isotopic evolution of our samples we find that the greatest impediment to u th dating of these sediments is not detrital contamination but rather post depositional remobilization of uranium examining u th data in these contexts we identify samples that have likely experienced the least amount of alteration and use dates from those samples as constraints for the age depth model our work has several lessons for future attempts to u th date lake sediments namely that geologic context is equally as important as the accuracy and precision of analytical measurements in addition we caution that significant geologic scatter may remain undetected if not for labor intensive tests of reproducibility achieved through replication as a result of this work the deep sediment core from lake junin is the only continuous record in the tropical andes spanning multiple glacial cycles that is constrained entirely by independent radiometric dates

travertine mounds of the cave and basin national historic site banff national park the cave and basin national historic site is a fan shaped travertine deposit associated with four thermal spring outlets tentative age dating of the travertine mound indicates growth initiated with onset of the late holocene shift to more humid and cool climate conditions and suggests that the flow of thermal waters was limited during the hypsithermal which in turn places constraints on the evolutionary biology of endemic species in the spring system two large caves and one collapsed cave structure are developed within the deposit cave development is in response to both physical erosion of till underlying the travertine and acid gas attack of calcite that makes up the deposit this process is buffered by formation of reaction crusts of gypsum on the interior cave walls only minor modern travertine growth occurs due to historic flow control measures understanding the flow of water through the historic site is critical for long term preservation

late quaternary vegetation history of wilcox pass jasper national park alberta five pollen zones are recognized in a radiocarbon and tephra dated core from an alpine site at an elevation of ca 2355 masl in wilcox pass jasper national park and record late quaternary vegetation history the two lower zones underlie material dated at 9600 305 yr b p gx 8785 and record early postglacial vegetation the basal zone wp1 containing an artemisia dominated assemblage represents tundra vegetation after deglaciation in zone wp2 arboreal pollen mainly diploxylon pine becomes dominant and represents a lodgepole pine forest the pollen assemblage of zone wp3 which initially contains large amounts of haploxylon pine as well as picea and abies pollen shows a transition from a forest with large amounts of whitebarkpine to vegetation resembling present day subalpine forest during this phase temperatures were probably warmer than present zone wp4 beginning after the influx of mazama tephra 6800 yr b p to the site records an expansion of the subalpine forest to higher elevations with a warmer climate in zone wp5 beginning about 2800 yr b p values of the main arboreal components fluctuate indicating cooler temperatures and less favourable environmental conditions probably associated with neoglacial ice advances the environmental trends observed from this record accord with those from other vegetation records in the canadian rockies

early holocene climate at castle peak southern coast mountains british columbia canada clague j j mathewes r w buhay w m and edwards t w d 1992 early holocene climate at castle peak southern coast mountains british columbia canada palaeogeogr palaeoclimatol palaeoecol 95 53 67 new palynological radiocarbon and stable isotope data from castle peak m the southern coast mountains indicate that the earl holocene climate of southern british columbia was warmer and perhaps drier than today fossil wood fragments are common above timberline at castle peak and have yielded 13 radiocarbon ages ranging from 9 1 ka to 8 i ka this evidence for higher timberline during the early holocene is in agreement with pollen data indicating a warmer and possibly longer summer growing season in this area during the early holocene and is consistent with theoretical considerations based on milankovitch forcing of climate change the oxygen and hydrogen stable isotope composition of fossil wood cellulose is similar to that of living trees in the same area growing season relative humidity values derived from the isotopic data provide some support for episodes of dryness at times of elevated timberline although the majority of paleohumidity estimates fall within the range of modern moisture levels

yardsticks for industrial tomography seismic tomography has been developed and applied for decades in seismological applications and for basic research purposes during the last decade large scale applications in the oil and gas industry became standard as tomostatics and velocity modelling for pre stack depth migration in this paper i take a snapshot of some current industrial applications quantifying practical aspects by yardsticks such as data and model size and i try to draw a road map for the current decade

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

a mid holocene vegetational and climatic record from the subalpine zone of the maligne valley jasper national park alberta canada abstract pollen macrofossils and isotopic data 13 c 18 o from gastropod shells are used to reconstruct holocene vegetational and climatic changes for a lower subalpine forest site elevation 1690 m in the maligne valley jasper national park alberta subalpine forest has characterized the site since the inception of the sedimentary record in this small pond ca 8500 yr b p in contrast to the vertical timberline fluctuations recorded at nearby sites above present tree line vegetational changes at the site appear to have been mainly horizontal i e forest cover and tree density expanded or contracted laterally in response to climatic warming or cooling at maligne lake forest cover was probably at its maximum extent about 7500 yr b p when pseudotsuga and other montane elements had migrated to this elevation but did not displace the existing vegetation the modern mosaic of discontinuous subalpine forest and extensive dwarf birch dominated damp meadows and fens emerged only during the last 1300 years a warmer neoglacial episode dated ca 2600 3400 yr b p is indicated by increases in the temperature limited gastropod lymnaea palustris and by progressive enrichment in the 18 o and 13 c contents of their shells summer temperatures during this period which has been tentatively identified elsewhere in the canadian rockies may have risen by as much as 1 8 c

late quaternary environmental change in the lake o hara region yoho national park british columbia abstract palaeoenvironmental reconstructions for the upper cataract brook valley are derived from radiocarbon and tephra dated cores recovered from subalpine lake o hara and alpine opabin lake located near the continental divide in the central canadian rocky mountains late quaternary vegetational and climatic changes are based on pollen and macrofossil data and are supplemented by preliminary diatom data the postglacial colonizing vegetation prior to ca 10 100 yr b p at lake o hara and before ca 8530 yr b p at opabin lake was a shrub herb community dominated by artemisia gramineae and alnus pioneering forests at both sites were composed of pinus cf albicaulis flexilis and abies with lesser abundances of picea and pinus cf contorta timberline remained above the elevation of opabin lake at least 90 m above modern timberline elevation during the period ca 8500 yr b p to ca 3000 yr b p in response to warmer climatic conditions associated with restricted glacial activity forest compositions resembling the modern subalpine picea abies forest had developed by the end of this period the period ca 3000 yr b p to present was marked by deteriorating climatic conditions associated with renewed glacial activity in the opabin cirque and declining timberlines to below the elevation of opabin lake glacigenic sediments in the opabin record from the post bridge river ca 2350 yr b p interval are associated with reduced diatom production and a change in dominant diatom taxa to those characteristic of turbid water conditions and unstable catchment areas

holocene tree line and climate change on the queen charlotte islands canada palynological study of two subalpine ponds on the queen charlotte islands reveals changes in tree line and climate during the holocene the findings agree with previous reconstructions from nearby louise pond on the queen charlotte islands that suggest a warmer than present climate and higher than present tree lines in the early holocene ca 9600 660014c yr b p basal ages at sc1 pond and shangri la bog indicate that the basins did not hold permanent water before 720014c yr b p consistent with a warmer and drier early holocene previously inferred from louise pond pollen and plant macrofossils indicate the initial establishment of subalpine conditions by 6090 9014c yr b p similar to the 5790 13014c yr b p age for cooling inferred from louise pond conditions similar to present were established at sc1 pond by 3460 10014c yr b p confirming the previous estimate of 340014c yr b p at louise pond this 340014c yr b p vegetation shift on the queen charlotte islands corresponds with the beginning of the tiedemann glacial advance in the south coastal mountains of british columbia ca 330014c yr b p the peyto and robson glacial advances between 3300 and 280014c yr b p in the rocky mountains and climatic cooling inferred from palynological studies throughout southern british columbia northern washington and southeast alaska these findings confirm that changes in regional climate influenced changes in vegetation in coastal british columbia

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