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

seismic stratigraphy of waterton lake a sediment starved glaciated basin in the rocky mountains of alberta canada and montana usa abstract upper and middle waterton lakes fill a glacially scoured bedrock basin in a large 614 km2 watershed in the eastern front ranges of the rocky mountains of southern alberta canada and northern montana u s a the stratigraphic infill of the lake has been imaged with 123 km of single channel fm sonar chirp reflection profiles offshore sonar data are combined with more than 2 5 km of multi channel land based seismic reflection profiles collected from a large fan delta three seismic stratigraphic successions sss i to iii are identified in waterton lake resting on a prominent basal reflector bedrock that reaches a maximum depth of about 250 m below lake level high standing rock steps reigels divide the lake into sub basins that can be mapped using lake floor reflection coefficients a lowermost transparent to poorly stratified seismic succession sss i up to 30 m thick is present locally between bedrock highs and has high seismic velocities 1750 2100 m s typical of compact till or outwash a second stratigraphic succession sss ii up to 50 m thick occurs throughout the lake basin and is characterised by continuous closely spaced reflectors typical of repetitively bedded and rhythmically laminated silts and clays most likely deposited by underflows from fan deltas paleo depositional surfaces identify likely source areas during deglaciation intervals of acoustically transparent seismic facies up to 5 m thick are present within sss ii at the northern end of upper waterton lake sss ii has a hummocky surface underlain by collapse structures and chaotic facies recording the melt of buried ice sediment collapse may have triggered downslope mass flows and may account for massive facies in sss ii a thin holocene succession sss iii

little ice age glacial activity in peter lougheed and elk lakes provincial parks canadian rocky mountains dendrochronological lichenometric and i4c studies at 14 glacier sites in peter lougheed and elk lakes provincial parks were used to develop a chronology of little ice age glacial events the earliest indications of glacial activity are represented by moraines deposited prior to the 16th century a major glacial expansion in the 17th century is recorded at three sites where i4c dates show glaciers reached their maximum down valley positions lichenometric dates and tree growth suppression records show a phase of glacial activity early in the 18th century for which there is only sparse morainic evidence most moraines in the area date from a glacial advance culminating in the mid 19th century and moraine formation was complete everywhere by the late 1800 s recessional moraines are rare in the study area and indicate that ice front retreat has been relatively continuous since the 19th century the glacial chronology developed in this work is comparable to that reconstructed for both the main ranges of the canadian rockies and the coast ranges of the southern cordillera resum6 les ctudes dendrochronologique 1ichcnomctrique et radiomktrique au i4c de 14 sites rcalisces dans les parcs provinciaux de peter lougheed et de elk lakes ont servi a ctablir une chronologie des cvbnements glaciaires survenus durant le petit bge glaciaire les plus anciens indices de l activitk glaciaire sont reprcsentcs par les moraines dcposces anttrieurement au xvie sibcle une expansion glaciaire majeure durant le xviie sibcle est enregistrke sur trois sites ou les dates au 14c rcvklent la prksence de glaciers avec leurs positions de progression maximale vers le bas de la vallce les datations fondces sur la 1ichcnomctrie et sur les registres de cessation de la croissance des arbres montrent la prcsence d une phase d activitk glaciaire au debut du xviiie sibcle qui a iaissc peu de dcp8ts morainiques dtcelables la plupart des moraines qui apparaissent dans la rcgion datent d une avancce glaciaire qui avait atteint son apogce d extension au milieu du xixe sikcle et leur construction fut complctce vers la fin des annces 1800 les moraines de rkcession sont rares dans la rcgion ctudik cependant elles indiquent que depuis le xixe sibcle il y a eu un retrait relativement continu du front glaciaire la chronologie glaciaire ktablie dans la prcsente ctude est analogue i celle reconstruite pour les chaines principales des rocheuses du canada et pour le domaine c8tier de la cordillbre mkridionale traduit par la raaction

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

diagenetic and catagenetic products of isorenieratene molecular indicators for photic zone anoxia a wide range of novel diagenetic and catagenetic products of the diaromatic carotenoid isorenieratene a pigment of the photosynthetic green sulphur bacteria chlorobiaceae has been identified in a number of sedimentary rocks ranging from ordovician to miocene compound identification is based on nmr mass spectrometry the presence of atropisomers and stable carbon isotopes atropisomers contain an axially chiral centre which in combination with other chiral centres results in two or more diastereomers that can be separated on a normal gc column chlorobiaceae use the reverse tca cycle to fix carbon so that their biomass is enriched in 13c high 13c contents of isorenieratene derivatives therefore support their inferred origins isorenieratene derivatives include c 40 c 33 and c 32 diaryl isoprenoids and short chain aryl isoprenoids with additional aromatic and or s containing rings c 33 and c 32 compounds are diagenetic products of c 33 and c 32 carotenoids formed from isorenieratene during early diagenesis through expulsion of toluene and m xylene respectively cyclisation of the polyene acyclic isoprenoid chain can proceed via an intramolecular diels alder reaction followed by aromatisation of the newly formed ring sulphurisation is also an important process during early diagenesis competing with expulsion and cyclisation sulphur bound isorenieratane is released during progressive diagenesis due to cleavage of relatively weak ss and cs bonds cleavage of c c bonds during aromatisation of newly formed rings and during catagenesis yields short chain compounds the inherent presence of a conjugated double bond system in carotenoids implies that similar diagenetic and catagenetic reactions can occur with all carotenoids chlorobiaceae live at or below the oxic anoxic boundary layer and require both light and h 2s the presence of isorenieratene or its diagenetic and catagenetic products in ancient sedimentary rocks and crude oils is therefore an excellent indication for photic zone anoxia in the depositional environment diagenetic and catagenetic products of isorenieratene are expected to find applications in reconstruction of palaeoenvironments and in oil oil and oil source rock correlation studies their presence in several petroleum source rocks suggests that anoxia is an important environmental parameter for the preservation of organic matter

evidence for a mazama like tephra deposited ca 10 000 bp at copper lake banff national park alberta mazama tephra is a widespread mid holocene stratigraphic marker dating to ca 6845 bp and is considered useful for the correlation of holocene events in western north america we present evidence from copper lake alberta for a tephra layer that underlies mazama tephra and appears to be a discrete tephra layer but that is indistinguishable from the conventional mazama tephra by microprobe analysis of glass shards three alternative hypotheses are considered to explain this tephra underlying mazama in situ position of an earlier mazama like tephra recycling of tephras and settling of tephra slabs through the gyttja the size distributions of birch pollen grains indicate that the mazama like tephra is in primary stratigraphic position in the early holocene gyttja and that sediment recycling has not destroyed the integrity of copper lake sediment stratigraphy it is concluded that most probably a mazama like tephra was deposited between 9700 and 10 500 bp if this in situ hypothesis is correct the id

the causes of piping in a set of abandoned agricultural terraces in southeast spain this study aims to identify some of the factors contributing to the piping process in abandoned terraces in seven sites located in the murcia region southeast spain the local landscape has the appearance of badland geomorphology possessing deep valleys which until the 1970s were terraced and cultivated the terraces have now been abandoned to the piping process the research focuses on the relationship between the size and position of pipes and the physical and geochemistry properties of the local highly dispersive marl lithology and the extent to which the reworking of the materials for terrace cultivation has exacerbated piping erosion morphologically the terracing in the stream beds has resulted in a series of gentle benches separated by steeper risers with variable drop riser height a series of flat infiltration surfaces result and because the resculpting produces a reduced bulk density infill with enhanced throughflow infiltrating water is forced along steep hydraulic gradients to a low outfall at the base of the riser paralleling studies of land levelling and terrace abandonment in similar materials elsewhere piping in the study area is shown to be closely related to the physical and chemical characteristics of the materials its sodicity and dispersive character considerable differences in structure texture mineralogical composition and material s surface crust and subsoil geochemical properties emerged from site signature plots and these results suggest that agricultural processes affect the dispersive character of the crust materials presumably because agricultural activity increases the buffering effect of organic acids on the dispersed clay this is supported by the observation that on the one site that was levelled but not used for agriculture a stable organically distinct crust like the abandoned agricultural sites has not formed the changes to the material s aggregate stability and bulk density properties when terracing occurs is examined but insufficient evidence is available from the data collected to unpick the causes of aggregate stability changes in the study plots the way in which differences between crust and subsoil enhance infiltration is discussed and the role of the terrace drop in influencing hydraulic gradients and pipe development is illustrated a possible index to describe the relationship between evacuated material volumes and the controlling parameters discussed above is tested it is concluded that terracing which is intended as a conservation practice has in dispersive materials actually enhanced piping leading to the abandonment of farming

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

upper ordovician stratigraphy of southampton island northwest territories the middle to late caradoc bad cache rapids formation of southampton island consists of three members a locally present thin siliciclastic unit overlain by a highly fossiliferous wackestone capped by a mudstone all deposited in a broad shallow shelf setting this formation is possibly unconformably overlain by the early ashgill boas river formation comprising a lower carbonate mudstone and an upper oil shale deposited in a local shallow subtidal restricted basin during a transgression early to middle ashgill strata of the churchill river formation are made up of a lower unit with coral bearing wackestone representing a return to normal marine conditions and an upper unit of noncoralliferous wackestones indicating a regional shallowing the latter is capped by the sixteen mile brook oil shale the middle to late ashgill port nelson formation contains evaporite casts and algal laminites suggesting a sabkha environment mound like structures in this formation may have resulted from solution

structural controls on the orientation of erosion gullies in mid western new south wales australia abstract the role of geology in determining the drainage network of gullying has been evaluated by quantitative methods of analysis at gully erosion sites in new south wales field evidence suggests that soil cracks are sites of preferential flow and erosion at both the surface and subsurface soil fabric and rock structure and weathering studies were undertaken to establish the inheritance of soil cracks from the underlying parent material gully orientation was correlated with the strike of joints and bedding planes in a range of rock materials including sedimentary intrusive and extrusive igneous and thermal and regional metamorphic rocks these units vary not only in terms of mineralogy but also in degree of weathering however all are steeply dipping structures usually exceeding 60 correlations exist between gully orientation and joints in the underlying material but the strength of the relationship varies according to the parent material in the ordovician hornfels where no correlation between joints and gully orientation occurred the evidence showed that gullying was controlled by faulting along the hornfels granite boundary these relationships support the view that throughflow processes are dominant in the development of gullies since convergence of runoff would not be expected to align with subsurface soil discontinuities

holocene tephrostratigraphy and glacial fluctuations in waterton lakes and glacier national parks alberta and montana waterton lakes national park in alberta and glacier national park in montana lie along adjacent sections of the continental divide in the rocky mountains in cirques or near divides there is evidence for two ages of glacial deposits younger deposits are generally well preserved poorly vegetated and bear no tephra and no or very small lichens older deposits are more poorly preserved better vegetated bear rhizocarpon sp lichens at least up to 92 mm in diameter and bear tephra the tephra often occurs in two different coloured horizons but both are compositionally equivalent to mazama tephra the older advance has a minimum age of about 6800 14c years bp and a probable maximum age of about 12 000 14c years bp it is correlated with the pre mazama crowfoot advance of the canadian rockies deposits of the younger advance are probably not too much older than mid 19th century because some glaciers began retreating from the deposits about then the younger advance is correlated to the cavell advance of t

northern iberian abrupt climate change dynamics during the last glacial cycle a view from lacustrine sediments abstract we present a palaeoclimatic reconstruction of the last glacial cycle in iberia ca 120 000 11 600 cal yrs bp based on multi proxy reconstructions from lake sediments with robust chronologies and with a particular focus on abrupt climate changes the selected lake sequences provide an integrated approach from northern iberia exploring temperature conditions humidity variations and land sea comparisons during the most relevant climate transitions of the last glacial period thus we present evidence that demonstrates i cold but relatively humid conditions during the transition from mis 5 to mis 4 which prevailed until ca 60 000 cal yrs bp in northern iberia ii a general tendency towards greater aridity during mis 4 and mis 3 ca 60 000 to 23 500 cal yrs bp punctuated by abrupt climate changes related to heinrich events he iii a complex highly variable climate during mis 2 23 500 to 14 600 cal yrs bp with the mystery interval mi 18 500 to 14 600 cal yrs bp and not the global last glacial maximum lgm 23 000 to 19 000 cal yrs bp as the coldest and most arid period the last glacial transition starts in synchrony with greenland ice records at 14 600 cal yrs bp but the temperature increase was not so abrupt in the iberian records and the highest humidity was attained during the allerod gi 1a to gi 1c and not during the bolling gi 1e period the younger dryas event gs 1 is discernible in northern iberian lake records as a cold and dry interval although iberian vegetation records present a geographically variable signal for this interval perhaps related to vegetation resilience

controlling factors of the size and location of large gully systems a regression based exploration using reconstructed pre erosion topography abstract the role of different factors potentially affecting the size and location of large gully systems is explored in two tributary basins of the tagus river s portugal the hillslopes of these basins corresponding to tertiary sedimentary formations are affected by hundreds of large gully systems varying in extent from somewhat 2 to 3 ha a study set of 90 gully systems were vectorized from aerial ortophotos and analysed in relation to a set of potential control variables obtained by reconstructing the pre erosion topography multiple linear regression and logistic regression were combined in order to investigate controls over the general morphometry of these landforms area perimeter and sinuosity and their location in the respective basins results indicate that gully systems initiated as bank gullies in response to an incision by the drainage network in both basins and then evolved as a function of upslope contributing area developing progressively more sinuous outlines as a result of headcut bifurcation pre erosion topographic form was shown to have only a marginal effect with results suggesting gully systems have grown essentially through mass movements in headcuts and sidewalls influenced by subsurface water

compositional variability of mazama tephra magnetites magnetites of anomalous composition found in association with known holocene tephras in banff and jasper national parks were originally thought to represent a new tephra of unknown origin but were later associated with mazama tephra at two other sites in alberta new data from alberta british columbia and montana confirm the compositional variability of mazama tephra the range of magnetite compositions presumably was produced by an inhomogeneous magma chamber for which there is evidence in the case of the mazama eruption

conodont paleontology and biostratigraphy of ordovician carbonates and petroliferous carbonates on southampton baffin and akpatok islands in the eastern canadian arctic carbonate and petroliferous carbonate units oil shales on southampton baffin and akpatok islands have yielded a total of 2277 conodonts the more biostratigraphically useful of which indicate not all units are correlative the boas river shale the lower of the two petroliferous units on southampton island overlies the bad cache rapids group and contains a diverse fauna including elements of amorphognathus ordovicicus branson and mehl previous reports have indicated the presence of culumbodina penna sweet a species whose range only barely overlaps that of a ordovicicus in the middle maysvillian carbonate beds and bedding plane surfaces of the higher red head rapids formation at sixteen mile brook yielded a ordovicicus faunas containing aphelognathus cf a divergens sweet these beds are likely richmondian since a divergens is known elsewhere only from richmondian strata a metasicula of glyptograptus hudsoni jackson several natural conodont assemblages and fused enigmatic coniform el

badland dynamics in the central pyrenees temporal and spatial patterns of weathering processes the genesis and development of badlands is controlled by bedrock lithology topography and climate the development of badlands in the central spanish pyrenees is favoured by the presence of marls and a climate with a marked seasonality the combination of these factors results in active hydrosedimentological processes the aim of the present work was to study the dynamics of badlands in the central pyrenees with a focus on the temporal and spatial patterns of the dominant weathering processes the study area was a small mountain catchment and we focussed on the continuous observation of a number of physical parameters that control regolith development and weathering processes samples collected from different depths at sites with different aspects enabled temporal comparisons of the factors involved in the development of surface regolith that can be considered as indicators of the weathering of the marls these indicators were then related to environmental variables moisture and temperature atterberg limits were established and related to moisture content to explain slope dynamics and related processes finally analyses of carbonate content were performed in the laboratory the results validate the employed methodology supporting our description of weathering processes the established chronological sequence and the relation of these processes to climatic and topographic parameters the results obtained since january 2004 show that the chosen indicators are sensitive to seasonal dynamics variations in temperature and water supply and slope aspect the development and dynamics of regolith on north facing slopes is more active than that on south facing slopes freeze thaw is the main weathering process on north facing slopes while south facing slopes are dominated by the development of crusts associated with wetting drying processes washing effects and lower temperatures upon north facing slopes mean that the dissolution of carbonates is more pronounced in such areas compared with south facing slopes especially within the upper layers of the regolith copyright 2006 john wiley sons ltd

testing the reliability of detrital cave sediments as recorders of paleomagnetic secular variations seso cave system central pyrenees spain abstract a paleomagnetic study has been carried out on a waterlaid detrital sedimentary sequence of 240 cm thick within the seso cave system west central pyrenees in these sediments seven charcoal samples were dated using 14c ams ranging from 2080 to 650 cal yr bp 130 bc 1300 ad two levels of human occupation of the cave have been recognized by ceramics associated to the iberian period and to the roman period respectively the detrital sedimentary sequence is made of autochthonous piping detached material from the eocene marls host rock inside of the cavity and allochthonous stream transported sediments from the outside sediments the autochthonous material first 100 cm made of fine grain laminated sediments lutites and marls corresponds to pond facies the allochthonous material 190 240 cm is made of lutites and sands and corresponds to stream facies and both facies are mixed from 100 to 190 cm the increase in sedimentation rate towards the end of the sequence stream facies points to an intensification of the alluvial activity as a possible consequence of a more arid climate during the medieval climate anomaly for the paleomagnetic study 44 discrete cylindrical samples were taken along the detrital sequence the values of the natural remanent magnetization and magnetic susceptibility are significantly lower in the pond sediments than in the stream sediments the declination and inclination of the paleomagnetic characteristic component sister samples analyzed by both alternating field and temperature demagnetizing procedure of each depth point is compared to the spanish archeomagnetic catalog and available geomagnetic models arch3k 1 cals3k 4 cals10k 1b and scha dif 3k in order to determine the accuracy of these sediments recording the earth s magnetic field results suggest that these sediments poorly record the earth s magnetic field however paleomagnetic inclination shows similar results between both demagnetizing methods and the inclination is well recorded especially in the younger stream facies the lack of archeological remains with absolute dates from 925 to 1545 cal yr bp in the iberian paleomagnetic secular variation reference curve has prevented up to now the study of that time period therefore the inclination data from the seso cave deposit is the first record of the iberian paleomagnetic secular variation during most part of the medieval time and they are closer to the inclination values of one geomagnetic model cals10k 1b

regional significance of an early holocene moraine in enchantment lakes basin north cascade range washington abstract the upper enchantment lakes basin in the north cascade range of washington displays two moraine belts each recording an episode of glacier advance after the end of the last glaciation the inner belt the brynhild 0 1 to 0 5 km beyond existing glaciers postdates mount st helens wn tephra 450 yr old which lies only beyond the moraines the morainal surface is only slightly weathered is almost barren of lichens and is devoid of soil evidence suggesting that the brynhild moraines are no more than a century old the outer moraine the brisingamen 0 3 to 0 7 km beyond existing glaciers is weathered and is covered with large lichens on and behind the brisingamen moraine the mazama ash 6900 yr old is present beneath the mount st helens yn and wn tephras despite more than 7 millennia of weathering the rock surface behind the brisingamen moraine is measurably less weathered than the surface beyond which was last glaciated during the rat creek advance about 13 000 yr ago the age of the brisingamen moraine therefore is probably early holocene the brisingamen moraine evidently correlates with moraines near glacier peak near mount rainier in northeastern and central oregon in the southern canadian rockies and in the northern u s rocky mountains these regional effects suggest that a climatic episode of cooling or increased snowfall affected the entire region some time during the early holocene

detection of soil pipes through remote sensing and electrical resistivity method insight from southern western ghats india abstract every year during the monsoon period june september series of land subsidence incidences are reported from the southern western ghats in india these land subsidences occur primarily due to subsurface erosion which leads to formation of soil pipes these soil pipes are geo morphologically an outcome of land degradation process that significantly influences the hill slope hydrology which makes the slopes vulnerable and affects the human lives as well however detection of these subsurface pipes remains a serious challenge most of the previous studies are based on surface investigations without considering the subsurface features the present study aims to provide a more detailed account of these less studied geomorphic features soil pipes using an integrated approach the main purposes of the present study are to 1 describe the characteristic of the soil pipes and 2 to quantify the scale of piping activity based on both surface and subsurface investigations in watershed scale the remote sensing and gis platform were used to delineate watershed boundary identify geo morphological setup of the terrain detailed landuse information and to bring out change in landuse landcover pattern the geomorphic mapping was carried out to identify the type of pipes location of its inlet outlet and other subsequent deformation features the resistivity survey was done to map geometry of the pipe piping network subsurface lithology and get the water table depth the resistivity survey results indicate that the density of pipes are more than the estimated through surface mapping similarly the length of the pipes is more than the mapped pipe through the surface mapping the combined results suggest that the region is rich in these kinds of pipe features and may create hazard to the society residing in those areas this study further underlined the importance of detailed study about soil piping phenomena to minimize its threat to human habitation and to provide specific recommendations to prevent the recurrence

late ordovician conodont biostratigraphy and redefinition of the age of oil shale intervals on southampton islandearth science sector contribution 20100054 southampton island was located on the north margin of the hudson bay basin one of the largest paleozoic sedimentary basins in north america the upper ordovician sequence on the island includes the bad cache rapids and churchill river groups and the red head rapids formation the latter contains three oil shale intervals in its lower part which may have significant potential as hydrocarbon source rocks but their precise biostratigraphic position remains unclear numerous conodont elements from 14 localities allow establishment of four interval zones throughout the upper ordovician on southampton island the belodina confluens and pseudobelodina v vulgaris zones in the bad cache rapids group which are correlative to the upper edenian lowest richmondian stage the amorphognathus ordovicicus zone from the uppermost bad cache rapids group to the top of churchill river group to the lower richmondian stage and the rhipidognathus symmetricus zone in the red head rapids formation to the upper richmondian

quantitative study of piping processes in badland areas of the ebro basin ne spain abstract in the ebro basin piping is an ubiquitous erosion process in badland areas occurring in two main situations on slopes of exposed tertiary clays and in recently incised silty clay holocene valley fill sediments the quantitative importance of the main factors controlling piping processes in those conditions was obtained by statistical analysis based on multiple and stepwise regressions piping erosion is strongly related to a high sodium absorption ratio sar which favours clay dispersion however the statistical analysis indicates that the chemical characteristics and the physical chemical behaviour are a necessary condition but are not sufficient on their own to develop piping processes on the slopes piping is controlled by the physical and chemical properties of the material such as the dispersion index the granulometric fraction smaller than 4 m ph and crack density in the valley fill sediments piping is mainly controlled by the sulphate concentration in the water extract from saturated paste which is also associated with high sar values and the dispersion index in both geomorphic situations piping is always related to high crack density and high topographic gradient

upper ordovician conodont biostratigraphy and revised lithostratigraphy and geological map akpatok island ungava bay nunavut stratigraphic units exposed on akpatok island ungava bay nunavut were previously recognized as boas river and akpatok formations their biostratigraphic ages and correlations in particular the stratigraphic position and age of the organic rich boas river formation were largely based on limited data new detailed field observations have recognized three stratigraphic units namely the amadjuak akpatok and foster bay formations in which extensive microfossil sampling recovered over 22 000 conodont elements from 66 productive samples from both outcrops and rubble at over 20 localities in four areas four upper ordovician conodont zones and one unzoned interval are established for the three redefined formations belodina confluens and oulodus velicuspis interval zones are confined to the exposed amadjuak formation and correlated to edenian and maysvillian amorphognathus ordovicicus plegagnathus dartoni concurrent range zone occurs with the akpatok formation and correlated to lower richmondian rh

origin and evolution of sarinena lake central ebro basin a piping based model abstract the origin and nature of the numerous lakes in the central ebro basin have been interpreted according to the prevailing arid or semiarid conditions the easily eroded materials and the solubility of the gypsum and or carbonate rich tertiary cenozoic substratum involving important dissolution karstic and or aeolian deflation however the origin of sarinena lake the largest in the central ebro basin remains unknown since the typical lake generating processes in the region are not applicable this work provides significant clues to the genesis and evolution of sarinena lake in a regional context the combination of geomorphological mapping and high resolution lidar data together with sedimentological observations the characterisation of soils and sediments around the lake and the application of high resolution geophysical techniques suggest that piping is the major genetic process driving the evolution of the sarinena depression and lake field evidence demonstrates that piping is at present the most important erosive process in the region generating significant collapse and surface lowering sarinena lake is located within a deep endorheic depression excavated from na rich tertiary materials this work hypothesises that once an early fluvially originated palustrine area had developed the progressive lowering of the regional water table linked to regional fluvial incision favoured the establishment of a hydrological gradient high enough to trigger piping processes within the claystones and siltstones underlying the original palustrine area the quaternary evolution of the sarinena lacustrine basin was then controlled by successive water table fluctuations linked to different phases of incision and alluvial deposition in the surrounding fluvial systems all the evidence supporting a piping related origin for this lake together with examples of lakes generated by similar processes in different contexts is used to propose a new genetic type of lacustrine depression generated by piping processes under favourable conditions

upper pleistocene interstratal piping cave speleogenesis the seso cave system central pyrenees northern spain abstract the seso cave system scs south central pyrenees northeastern spain develops in poorly soluble marly interstratum between limestone beds of eocene age we propose an innovative and singular pseudokarstic speleogenetic model under vadose conditions based on cave morphological evidence physicochemical and mineralogical characteristics of the eocene marly host rock u th dating of cave deposits and local geological and geomorphological information eocene marls are shown to be sensitive to dispersion processes supported by their high clay content and the high concentration of sodium and low electrical conductivity in the seepage water runoff inside the cave results from water that infiltrates through joints and seepage water in cave walls thereby piping processes become very active triggering mechanical scouring and outwashing mechanisms the hydraulic gradient required to develop piping activity is determined by regional fluvial incision the base level controlling water discharge during opening of the scs coincides with a terrace of the ara river dated at 65 ka bp considering this age as well as the u th age of the oldest speleothems dated in the cave at 38 ka bp the timing of the scs interstratal piping cave speleogenesis is constrained to the upper pleistocene very likely at the end of marine isotope stage 4 during a period characterized by high water availability following glacial retreat in northern iberian mountains

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

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

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

early holocene glacier advance in the north cascade range washington moraines and glacial drift of the white chuck advance were deposited in early holocene time in cirques near glacier peak washington these sediments overlie glacier peak tephra including layers g n f c m t and b which were erupted between about 12 500 and 11 250 yr b p white chuck drift is overlain by mazama tephra layer o deposited about 6 700 yr b p charcoal collected from till deposited during the white chuck advance is about 8 300 to 8 400 radiocarbon years old indicating that the glacial advance that deposited the till occurred about this time and that a previously unrecognized period of cooling and or increased precipitation of sufficient intensity to produce glacial advances comparable to or greater than those of the recent little ice age occurred in early holocene time in the north cascade range other pre altithermal moraines from the cascades the rocky mountains laurentide canada and baffin island may have been produced during this cool period

the role of some site geochemical processes in the development and stabilisation of three badland sites in almeria southern spain samples of both surface and subsurface soils were collected on various surfaces in three badland areas of differing ages tabernas vera and mocatan in almeria province southern spain data were explored with the aim of identifying any diagnostic geochemical relationships between site ec ph sediment size and sar which might constitute typical signatures for site materials with some success data for the three sites are further used to explore the hypothesis that changes in site geochemistry through time are involved in badland stabilisation it was found that 1 the physico chemical properties of the three sites can be differentiated by the functional relationship between ec and sar and this may represent a useful tool in characterising sites where piping predominates 2 there is some equivocal evidence that sediment size distribution may play an additional role in site diagnosis and evolution and 3 surfaces appear to lose sodium over time the suggestion being that sodium is either progressively buffered by calcium during leaching or exchanges with hydrogen on the cation exchange sites under a vegetation cover since other research suggests that smectite can also relocate down the profile on some marl sites reducing hydraulic conductivity and suppressing pipes we argue that the surface at tabernas may be capable of long term autostabilisation in which piping intensity progressively reduces however this possibility really applies only to fine grained densely structured materials and evidence from the silty triassic rich unit in the mocatan basin suggests that without a high clay content piping may be expected to increase through time from this standpoint contemporary badland morphology at mocatan does not represent an early stage of the forms seen in vera and tabernas

application of geoarchaeological evolutionary models for the interpretation of complex archaeological structures in the central ebro basin spain in landscapes that are extremely sensitive to small environmental changes like some mediterranean areas archaeological contexts could present some problems to their interpretation and evolutionary reconstruction this is the case of los pedregales archaeological site located in the hoya de huesca ne of spain where several stone mounds of unknown age and function were found in an extensive badland the geomorphological edaphological and archaeological study together with radiocarbon and osl datings and contextualization into the geomorphological regional framework made it possible to interpret these structures and to establish an evolutionary model it was determined that they were silos excavated in pleistocene sands and silts unit 1 during the visigothic and early muslim epochs 6th 7th centuries and that they were later filled with limestone blocks successive aggradational and degradational stages units 2 3 and 4 during mca medieval climatic anomaly and lia little ice age periods covered and incised the area leaving the shape of positive structures included in the badland

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

clay mineralogy as a crucial factor in badland hillslope processes abstract comprehensive and important work has been done in understanding badland processes on both the big scale and more recently on smaller scale in order to understand the subtle differences between sites however most studies lack important information regarding clay mineralogy and their importance for weathering processes type and rate of weathering depend on material physico chemical properties climatic regimes and slope characteristics as weathering progresses the surface conditions change influencing erosion processes usually badland lithologies are reported as sodium rich highly dispersive materials but that is not invariably true the primary objective of this study is to show that clay minerals have an important role in defining surface and subsurface processes on badland hillslopes field studies conducted in dinosaur park badlands alberta canada chinguacousy badlands ontario canada and sestino badlands tuscany italy have shown that there are two dominant clay rich lithologies smectite rich and smectite poor mudrocks different surface crust and weathering profiles were observed on smectite rich mudrocks during two field years with distinct precipitation inputs after a dry fall winter season the popcorn surface was very well developed 2 3 cm the subsurface layer 10 15 cm thick overlaid the layer of smaller shards followed by the unweathered material after a very wet fall winter season the surface layer was denser and thinner 0 5 cm with wider cracks and a thin subsurface layer attached to the crust weathering profiles on smectite poor lithologies did not show any differences with variable climatic conditions a thin surface layer was composed of soft thin and small 0 5 0 3 0 1 cm shards a layer of larger shards overlying unweathered material was beneath it in order to better understand the described occurrences badland materials were monitored in controlled laboratory conditions during an incremental weathering experiment six samples of each material were subjected to 10 cycles of simulated rainfall which duration ranged 10 60 min very short rainfalls 10 20 min can cause swelling of clay minerals in smectite rich materials and formation of popcorn surface during drying periods during subsequent wetting drying periods the crust becomes flatter and denser and desiccation cracks become wider and deeper samples subjected to 50 and 60 min of rainfall showed maximum swelling after only one cycle of rainfall after this swift swelling samples became unstable and dispersive during subsequent wetting dispersion became dominant resulting in flatter surfaces thinner crust and narrower desiccation cracks smectite poor mudrocks appeared to be resistant to variable wetting and drying large shards broke down into smaller due to differential swelling of illite and chlorite once they were reduced to tiny flaky shards the surface became compacted the surface cracks served as the initial pathways for sediment and water movement knowing if the material is smectite rich or smectite poor can help in prediction of processes and the erosion rates the amount intensity and duration of precipitation will determine not only the rate of weathering but also the type of the weathered surface on smectite rich surfaces smectite poor materials appear to be more resistant to change in precipitation

temporal distribution of suspended sediment transport in a humid mediterranean badland area the araguas catchment central pyrenees abstract this paper analyses the temporal patterns of suspended sediment yield in the araguas catchment central spanish pyrenees a small experimental catchment with extensive badlands the catchment has been monitored since 2004 to study weathering erosion and hydrological and sediment responses to understand the superficial dynamics of a badland area in a relatively humid environment the development of badlands in the central spanish pyrenees is favoured by the presence of marls and a markedly seasonal climate the continuous observation of selected physical parameters and environmental variables enables us to establish seasonal patterns of weathering processes and identify those factors that control regolith development freeze thaw cycles in winter and wetting drying in spring summer are the main processes involved in regolith weathering thereby controlling slope development in combination with rainfall related erosion processes the 64 floods recorded during the study period december 2005 to january 2007 were used for a hydrosedimentological analysis the main observed features indicate that the araguas catchment reacts to all rainfall events resulting in steep rising and recession limbs on the hydrograph and a very short time lag floods show high suspended sediment concentrations and a heterogeneous temporal distribution related to seasonal variations in surface runoff production these differences increase the degree of complexity involved in studying sediment response suspended sediment concentration and transport mainly depend on rainfall volume maximum rainfall intensity peak flow and runoff occurrence finally the similarities among the obtained hydrographs sedigraphs and hyetographs in combination with the rapid response of most of the floods suggest a large contribution of overland flow derived mainly from infiltration excess runoff upon badland areas accordingly the significant correlations obtained between rainfall intensity and sediment concentration mainly during the dry season which suggest a single source area for both runoff and sediment also support the hypothesis of hortonian hydrological response within badland areas

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

holocene and latest pleistocene glacial chronology glacier national park montana moraines of two different age groups have been identified fronting the present day glaciers and snowfields in glacier national park montana the subdued vegetated moraines of the older group have been found at 25 sites mainly in the central part of the lewis range these older moraines are in places overlain by the mazama ash although the exact age of the moraines has not been determined by radiocarbon dating vegetative evidence and correlation with other pre altithermal age moraines in the rocky mountains suggest that these older moraines date from 10 000 bp or earlier whether these moraines are the product of a separate advance after the end of the wisconsin glaciation or are simply the product of the last advance or stillstand of wisconsin glaciers before final deglaciation is not known moraines of the younger group consisting of fresh bouldery rubble are common throughout glacier park tree ring analyses indicate that some of these younger moraines were deposited by advances that culminated du

badlands in marl lithologies a field guide to soil dispersion subsurface erosion and piping origin gullies abstract field scientists studying badland processes in mediterranean and semi arid climates require assurances that the material in which gullies are presented is not dispersive a dispersive context means first infiltration rates may be radically changing in very short periods due to swelling and deflocculation of clays second surface crusts could be the result of translocation of sodium into subsurface positions third rills may be formed or at least exacerbated by shallow subsurface erosion fourth large gullies with substantial up channel headcuts including so called bank gullies may have formed because subsurface pipes have collapsed and fifth that network connectivity and evolution may be principally internal being effected by subsurface pipe capture network integration and most importantly the bulk of the sediment moving around in the landscape is not being lost from the surface this paper presents a decision support tool to assist the effective diagnosis of a landscape s principal genetic process suite the soil s behaviour in response to its geochemistry in marls with high exchangeable sodium percentages esps is outlined in simple terms with minimum use of laboratory or field chemical investigations using examples the paper then presents a simple set of form indicators that can be used in the field to diagnose the possibility that subsurface process are dominating landscape erosion surface crust character ephemeral rills and large subsurface tunnel settings are explained and classified in a final section the geomorphological implications of piping in gullied landscapes are explored by reference to the literature on connectivity

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

sediment entrainment and transport in fluviokarst systems the primary geomorphic process active in the development of karst stream systems is generally regarded as bedrock dissolution however physical erosional processes may also be an important geomorphic agent in karst development the objectives of this study were to determine the sediment transport threshold in two fluviokarst streams the source of the sediment was internal to the karst basins the approach used was to calculate basal and critical shear stresses from streams in two karst systems to determine if and how frequently storm induced flows are capable of mobilizing stream sediment the fluviokarst systems investigated as a part of this research are capable of transporting 50 85 of their stream substrates during bankfull discharge conditions based on the discharge and precipitation frequency stream flows capable of entraining d50 and d85 particles occur at intervals of 2 4 and 11 7 months 0 98 yr respectively thus the sediment transport threshold in fluviokarst streams is exceeded by relatively common discharge events q 2004 elsevier b v all rights reserved

the influence of physico chemical material properties on erosion processes in the badlands of basilicata southern italy piping tunnelling appears to be one of the more significant methods of erosion in the badlands in the plio pleistocene marine sourced clays of the basilicata area in southern italy a detailed field investigation of the pedological textural mineralogical and geochemical properties of the clay rich terrains widely outcropping in two selected badland field sites the fossa bradanica area and the bacino di sant arcangelo was undertaken to further elucidate process variability across the complex site paralleling findings from other piped badlands certain physico chemical properties of the clays were found to influence the different erosional processes in fundamental ways the very dispersive nature of the materials enhances pipe enlargement so that subsurface flow rapidly becomes the dominant process causing pipe enlargement by a process of positive feedback the paper speculates on the progressive role of surface and subsurface processes in the genesis of all evolutional badland forms calanchi calanchi mammellonari and biancane in an early stage the calanchi mammellonari are produced as slope mounds become increasingly separated by a dense network of small inclined pipes in the intermediate part of the slopes a site which is presumed to favour elevated subsurface flow when the overburden collapses many cones are isolated in these portions of the slope a second stage follows in which overland flow dominates with the water canalizing into small gullies generated by the collapsed crust at the base of many slopes this same mechanism produces biancane as residual cones because of the structural weakness of piped materials mass movements cannot be ruled out in a few locations landsliding may be involved especially in the formation of calanchi mammellonari in this case the intersection of the vertical pipes with the impermeable substratum focuses subsurface flow and collapse of the surface along this failure plane subsequent remodelling occurs by surface processes since the catchment volume for large pipes no longer exists this interpretation differs from that of others who have argued that in other locations the biancane formation is linked to the development of large vertical pipes along tectonic joints

a re examination of the three most prominent holocene tephra deposits in western canada bridge river mount st helens yn and mazama abstract volcanic ash deposits tephra in western canada are instrumental in providing independent chronologic control for many archaeological and paleoenvironmental sites in alberta tephra are a key chronologic tool in a region where radiocarbon dates are often unreliable because of the prevalence of carbonate rich bedrock and other old carbon sources such as coal however many studies using tephra for age control particularly archaeological projects identify tephra simply through field characteristics or light microscopy in both alberta and british columbia many radiocarbon dates that were used to date key tephra deposits were bulk conventional ages on peat and lake sediments which are not always reliable these factors have led to uncertainty in the age and number of bridge river and mount st helens msh set y tephra present in the region and incomplete distribution maps new major element geochemical analyses from archaeological and sedimentary sites across south central alberta complemented by new analyses of tephra from british columbia and saskatchewan refine the distribution of the bridge river msh yn and mazama tephra new geochemical data radiocarbon dates and a detailed overview of proximal msh set y stratigraphy and geochemistry show that only one msh layer yn is present in this region rather than two msh set y tephra as previously suggested additionally re assessment of age data combined with new geochemical analyses confirm that there is also only one bridge river tephra a bayesian modelled age estimate is determined for msh yn based on new ams dates on the tephra and vetted existing conventional ages providing a revised age estimate for msh yn of 3805 3535 cal bp mean of 3660 cal bp

the early ordovician middle shale member am3 of the amdeh formation and further evidence of conodont faunas from the sultanate of omanap heward et al tremadocian floian shallow marine deposits from oman the middle shale member of the amdeh formation is interpreted to be of early ordovician age based on its trace fossils stratigraphic context and a newly discovered fauna of conodonts the member abruptly overlies the lower quartzite member which may be early cambrian and passes gradationally upward into the upper quartzite member which is probably early middle ordovician the 542 5 m thick middle shale member can be divided into two parts a shaly lower part and a sandy upper part that contains an influx of heavy minerals bioturbation by marine trace fossils is one of the most obvious characteristics of the member the shales and sandstones are interpreted to be of cruziana and skolithos ichnofacies and represent shallow marine shelf shoreface beach and coastal deposits sparse shelly fossils occur in the sandy upper part principally bivalves inarticulate brachiopods ostracods and conodonts the small assemblage of conodonts includes elements interpreted to be tremadocian tetraprioniodus drepanoistodus drepanodus scolopodus tropodus semiacontiodus and teridontus and others which may be floian or ancestral forms of floian taxa balognathidae gen et sp indet a b and aff erraticodon no acritarchs have been recovered probably due to high temperatures experienced during burial to 6 km it is likely that the middle shale member is the seaward equivalent of the mabrouk and barakat formations and an outcrop gamma ray log supports such a correlation the trace fossils sedimentology conodont fauna and the general lack of macrofossils are in keeping with the regional tremadocian floian of the arabian margin of gondwana

lichenometric dating science or pseudo science the popular technique of estimating ages of deposits from sizes of lichens continues despite valid criticism and without agreement on range of utility treatment of error and methods of measurement sampling and data handling a major source of error is the assumption that the largest lichen s colonized soon after deposition and will survive indefinitely recent studies on lichen mortality suggest that this assumption is untenable meanwhile the use of growth curves constructed from independently dated substrates is problematic for many reasons but this has not prevented the publication of baseless claims of accuracy and ages that are extrapolated well beyond data experiments indicate that numeric lichenometric ages are not reliable and in general do not advance the cause of quaternary science there are a few studies suggesting reliability and indeed there may be cases where lichens and growth curves actually provide realistic numerical ages but it cannot be foretold which lichen assemblages will provide good ages and which bad ages the logical conclusion is that no assumption of good ages can be made and that it is folly to assign numerical ages to a deposit on the basis of lichen sizes

a numerical approach toward the classification of magnetites from tephra in southern alberta high titanium glass encased magnetites associated with intermixed tephras in upper subalpine soils in banff national park are shown to be characteristic of mazama tephra and of regional significance similar magnetites occur in a mazama layer above a paleosol at fish creek alberta and within a sample of mazama ash ua 396 from windy point alberta detailed sampling and analysis of the fish creek tephra indicate that the magnetites do not represent a separate eruptive event or an older ashfall cluster analysis of glass encased magnetites from reference samples of mazama st helens y and bridge river ashes revealed composite grouping of mazama and bridge river magnetites and separate and strong groupings of high tio2 magnetites discriminant analysis identifies mgo tio2 and al2o3 as the most significant chemical discriminants between the various ashes discriminant function analysis identifies the high titanium magnetites as mazama in type and successfully classifies 96 of the tephra derived magnet

geochemical characterization and dating of r tephra a postglacial marker bed in mount rainier national park washington usa the oldest postglacial lapilli ash tephra recognized in sedimentary records surrounding mount rainier washington state usa is r tephra a very early holocene deposit that acts as an important stratigraphic and geochronologic marker bed this multidisciplinary study incorporates tephrostratigraphy radiocarbon dating petrography and electron microprobe analysis to characterize r tephra tephra samples were collected from tipsoo lake and a stream cut exposure in the cowlitz divide area of mount rainier national park field evidence from 25 new sites suggests that r tephra locally contains internal bedding and has a wider distribution than previously reported herein we provide the first robust suite of geochemical data that characterize the tephra glass compositions are heterogeneous predominantly ranging from andesite to rhyolite in ash to lapilli sized clasts the mineral assemblage consists of plagioclase orthopyroxene clinopyroxene and magnetite with trace apatite and ilmenite subaerial r t

uranium series chronology and environmental applications of speleothems an increasing number of scientists recognize the value of speleothems1 as often extremely well preserved archives of information about past climate vegetation hydrology sea level nuclide migration water rock interaction landscape evolution tectonics and human action well constrained data are required to document past changes reconstruct past patterns and predict future responses of the earth system at a wide range of spatial and temporal scales speleothems are particularly useful in this regard because they can be found in many locations of the globe sampled at high resolution and reliably dated using high precision uranium series techniques speleothems are bodies of mineral material formed in caves as the result of chemical precipitation from groundwater flowing or dripping in a cave most speleothems are composed of calcite formed by slow degassing of co2 from supersaturated groundwater but aragonite and gypsum forms are also common particularly near cave entrances where evaporative effects are important a host of different speleothem types decorate the walls ceilings and floors of caves and their mineralogy and morphology is a function of fluid flow and chemistry of waters feeding a particular location as well as the ambient conditions temperature chemistry light in the air or water filled void subaerial forms include the familiar stalagmites stalactites draperies flowstones subaqueous forms include rimstone pools rafts mammillary calcite wall coatings and dog tooth spar for an extensive review of the types of speleothem that have been observed see hill and forti 1997 speleothems are used in a multitude of ways to explore past environmental conditions perhaps the most fundamental of which is their very presence or absence deposition of speleothems relies on sufficient water supply and soil co2 to enable dissolution and transport of reactants in the vadose zone to underlying caves in arid or glacial times conditions may not have been favorable for speleothem formation

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

upper ordovician conodont biostratigraphy and the age of the collingwood member southern ontario canada11earth science sector ess contribution 20100302 the upper ordovician stratigraphy in southern ontario represents the clastic foredeep associated with the appalachian taconic orogeny transitioning northwest into coeval carbonate platform facies ten measured and sampled sections in both the collingwood area and on manitoulin island lake huron provide two relatively complete composite sections 277 and 95 m respectively through the marine part of the sequence a total of 100 2 kg samples collected for a conodont biostratigraphic study yielded 77 215 well preserved specimens taxonomic study of the fauna illustrated herein identified 34 species representing 22 genera and three taxa in open nomenclature taxonomic revisions are made to five species of pseudobelodina and one of rhipidognathus a new species pseudobelodina microdentata is established the fauna primarily represents the midcontinent province with incursions from the north atlantic province primarily in the collingwood area four conodont zones are recognized that help refine the ages

ordovician conodont biostratigraphy and redefinition of the age of lithostratigraphic units on northeastern melville peninsula nunavut northeastern melville peninsula nunavut canada preserves the stratigraphic record of the northwestern margin of the foxe basin the ordovician sequence on the peninsula includes the lower ordovician ship point formation and upper ordovician frobisher bay amadjuak akpatok and foster bay formations their biostratigraphic ages and correlations are poorly understood in particular it is unclear whether the organic rich boas river formation exists on the peninsula following extensive sampling of these stratigraphic units studies of numerous conodont elements from both outcrops and rubble at about 60 localities have established five conodont assemblages through the five lithostratigraphic units on the peninsula oepikodus communis jumudontus gananda assemblage in the ship point formation is correlated to the reutterodus andinus zone in the uppermost ibexian lower ordovician the other four assemblages from the upper ordovician are as follows appalachignathus delicatulus polyplacognathus ramosus

erosion processes in calanchi in the upper orcia valley southern tuscany italy based on multitemporal high resolution terrestrial lidar and uav surveys a 125 000 m2 calanchi badland in the province of siena tuscany was monitored with an unmanned aerial vehicle uav and terrestrial laser scanning over the period of one year tls terrestrial laser scanning was carried out on two sample slopes whereas the image acquisition of the uav covered the entire catchment in combination with ground control points the uav images were used to create orthophotos and 3d point clouds using the structure from motion sfm software photoscan the tls surface models indicate seasonal differences in erosion and deposition the surface change measured with sfm showed nearly 6 700 m3 of net material loss resulting from 8 700 m3 erosion and 2 000 m3 deposition these values reveal a mean annual surface lowering of 5 3 cm for the catchment additionally several geomorphological processes such as rill erosion slope wash and translational slides could be detected in the one year monitoring period a comparison of tls and sfm results showed differences in the calculated volumes of mobilised material these discrepancies resulted from shadowing effects and low point densities of the tls point clouds

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

lateral moraine stratigraphy and neoglacial history of bugaboo glacier british columbia abstract most studies of alpine glacial history have concentrated on terminal moraines but such moraines provide dates only for maximum extents of glaciers some lateral moraines have the potential for providing more complete glacial histories because deposition by distal flank accretion may result in sequences of stacked tills interpretation is aided by 1 the approximation that any continuous surface within the moraine parallel to the moraine s distal flank is isochronous 2 inset gulley fill deposits which provide information on ice margin history and 3 incorporated organic material which can be radiocarbon dated lateral moraine stratigraphy of bugaboo glacier in southeastern british columbia suggests that the glacier was fairly close to its maximum neoglacial extent about 2500 14c yr b p a slow general expansion punctuated by at least one minor retreat continued from that time and culminated probably in the last century