holocene river development and environmental change in upper wharfedale yorkshire dales england this paper provides the first radiometrically dated evidence of holocene alluvial landform development in upper wharfedale yorkshire dales four river terraces are identified terraces 1 and 2 are closely linked to late devensian and early holocene environmental change with gravel reworked from local glacial and periglacial sources prior to cementation by carbonate rich waters u series dating of cement provides age estimates for cementation of between ca 5 1 7 4 kyr bp for terrace 1 and ca 3 6 8 0 kyr bp for terrace 2 u series dating of tufas overlying terraces 1 and 2 produced ages of ca 4 2 4 5 kyr bp and ca 2 1 2 2 kyr bp respectively and provide upper age limits for terrace formation terrace 3 marks a change in sediment calibre supply and sedimentation style and 14c dating suggests that the principal source of fine grained material may be agricultural expansion in the yorkshire dales from ca ad 600 1350 cal yr bp radiocarbon dates indicate that terrace 4 was deposited from the eleventh century with initiation of the contemporary floodplain between the fifteenth and seventeenth centuries ad both these lowest units contain sediments contaminated with heavy metals as a result of mining activities within the catchment the evidence presented in this study is comparable to that of research undertaken in upland environments elsewhere in northern and western britain thereby adding to the corpus of information currently available for evaluating the fluvial geomorphological response to climate and vegetation change during the holocene copyright 2000 john wiley sons ltd

modelling differential catchment response to environmental change the caesar cellular automaton evolutionary slope and river model is used to demonstrate significant differences in coarse sediment transfer and alluviation in medium sized catchments when responding to identical holocene environmental changes simulations for four u k basins the rivers swale ure nidd and wharfe shows that catchment response driven by climate and conditioned by land cover changes is synchronous but varies in magnitude there are bursts of sediment transfer activity generally of rapid removal but with some sediment accumulation dspikest with longer periods of slow removal or accumulation of sediment in different valley reaches within catchments reach sensitivity to environmental change varies considerably some periods are only recorded in some reaches whilst higher potential sensitivity typically occurs in the piedmont areas of the catchments modelled here these differential responses appear to be highly non linear and may relate to the passage of sediment waves by variable local sediment storage and availability and by large and small scale thresholds for sediment transfer within each catchment differential response has major implications for modelling fluvial systems and the interpretation of field data model results are compared with the record of dated alluvial deposits in the modelled catchments d 2005 elsevier b v all rights reserved

preservation potential for late quaternary river alluvium valley sequences of late quaternary alluvial units reflect alluvial preservation as well as alluvial production factors effects of lateral channel migration incision aggradation and channel stability on preservation potential are explored and then considered in the light of 14 available data sets cartographically dated and model data based on lateral channel migration well mapped and dated late quaternary valley unit surveys and composite age frequency plots for dated alluvial units and flood sediments despite much expectable variation between sites and the complex effects of river activity combinations a common characteristic of the data sets examined is the significance of preservation factors lateral migration tends to eliminate older units as it creates new alluvial deposits whereas incision may lead to the preferential preservation of older units beyond the incision slot aggradational environments are likely to preserve more complete records although simultaneous lateral migration may eliminate possibly repeatedly the upper parts of alluvial units the common pattern of inset and incised streams within pleistocene and early holocene fills or bedrock gives finite extent to later units within narrowing valleys so that development of new valley floor units is necessarily at the expense of reprocessing earlier ones floods associated with both slack water deposits and berms are also responsible for the removal of accessible earlier materials thus limiting the preserved record of earlier events in light of these censoring effects of river activities the sequence of preserved late quaternary units within uk sequences is reconsidered it is concluded that preservation potential factors have led to spatial and temporal bias in the alluvial record and that both here and elsewhere preservation potential needs to be considered systematically alongside variable sedimentation resulting from allogenic environmental factors when interpreting the alluvial archive copyright 2003 john wiley sons ltd journal of quaternary science

geochemical records in holocene lake sediments of northern china implication for natural and anthropogenic inputs daihai lake is located in a hydrologically closed basin within the transitional zone of the east asian monsoon which has experienced significant lake level fluctuations the sedimentary sequence of a 12 08 m core was analyzed for mobile ca mg and sr and immobile elements al and fe and trace metals e g co ni cu zn and pb in order to study the changes of natural chemical compositions and the potential influences of the historical mining and use of metals during the holocene period climate changes have a significant influence on the concentrations of mobile elements in the holocene lake sediment high concentrations occurred during the times with high lake level resulting from enhanced catchment weathering due to strong monsoon effects different from these mobile elements the variation of immobile elements and trace metals in daihai lake sediment shows clear anthropogenic impact of the mining and use of metals in the last several millenniums a gradual increase in the concentrations and fluxes of metals from 5000 cal a b p is correlated well with the emergence of chinese civilization the concentrations and fluxes of these metals and immobile elements in the sediments increased rapidly between 2100 and 1250 cal a b p indicating the extensive use of metals during the warring states period 475 221 b c and the early han dynasty 206 b c 220 a d further increase of trace metals such as cu ni co and pb after the medieval warm period 1200 800 a b p likely reflects the increased metal emissions associated with extensive mining and utilization activities similar patterns of sedimentary metals between daihai lake in northern china and liangzhi lake in central china further indicate significant environmental impacts of the mining and utilization of metals in the progress of chinese civilization in the past several thousand years

sedimentary effects of cataclysmic late pleistocene glacial outburst flooding altay mountains siberia rudoy a n and baker v r 1993 sedimentary effects of cataclysmic late pleistocene glacial outburst flooding altay mountains siberia in c r fielding editor current research in fluvial sedimentology sediment geol 85 53 62 pleistocene glacial outburst floods were released from ice dammed lakes of the altay mountains south central siberia the kuray chuja lake system yielded peak floods in excess of 1 106 m 3 s 1 and as great as 18 106 m 3 s i the phenomenally high bed shear stresses and stream powers generated in these flows produced a main channel coarse grained facies of coarse gravel in 1 foreset bedded bars as much as 200 m high and several kilometers long and 2 degradational boulder capped river terraces giant current ripples 50 to 150 m in spacing composed of pebble and cobble gravel are locally abundant the whole sedimentary assemblage is very similar to that of the channeled scabland produced by the pleistocene missoula floods of western north america

evidence of flandrian valley alluviation in staindale north york moors the dovedale griff has incised into valley fill deposits in staindale to expose sub fossil wood at the base of a meander cut bank the wood includes oak quercus sp driftwood and apparently in situ stumps of willow salix sp and alder alnus sp an alder stump is dated at 6270 radiocarbon years bp fluvial gravels approximately 1 5 m thick have accumulated above the wood which has been exposed by renewed incision

identifying changing fluvial conditions in low gradient alluvial archaeological landscapes can coleoptera provide insights into changing discharge rates and floodplain evolution using examples from dated alluvial deposits in the trent basin uk this paper suggests that the waterlogged remains of insects mainly beetles can be used to detect the occurrence of varying discharge and changing patterns of flood plain evolution in low gradient alluvial landscapes of holocene age this approach may provide invaluable data where the finer grained nature of sedimentation means that other types of information such as coarse boulder berms are lacking comparison of coleoptera assemblages from three high energy and two lower energy deposits indicates that a number of distinctive characteristics can be identified and criteria can be set for the distinction of these two contrasting depositional environments this approach is tested using coleoptera remains recovered from a palaeochannel fill at spalford meadows in the lower trent valley the application of this methodology could contribute to the reconstruction of river histories a key factor in understanding the distribution of valley floor archaeological settlement patterns

fluvial development and the sediment regime of the lower calder ribble catchment northwest england in the lower reaches of the calder lancashire tributary of the ribble catchment northwest england five river terraces set into the surrounding glacial terrain have been mapped and their underlying sediments radiocarbon dated the earliest terrace t1 reflects sandur style deposition during deglaciation and it aggraded in a reach cut into glacial diamict and glaciolacustrine muds incision below t1 spanned the start of the holocene driven by a combination of reduced sediment supply under a stabilising landscape and lower base levels t2 had aggraded and was being abandoned by 4000 bc its formation latterly involving a period of comparative stability in terms of channel migration perhaps a function of extensive forest cover and sea levels reaching above present day levels the last 3000 years were marked by substantial changes in the sedimentary regime with increased and varying sediment supply driving cycles of cut and fill and greater lateral channel migration these changes coincided with the first widespread and substantial reductions in forest cover and a progression towards an agricultural landscape between the aggradation of terraces t3 and t4 there was a substantial increase in sediment supply which is broadly in keeping with the erosion history in the surrounding uplands this sediment slug appears to have induced a switch from highly sinuous meandering to lower sinuosity channels characterised by lateral scroll style migration late holocene vegetation changes particularly woodland removal driven by anthropogenic land pressure appear to have rendered the floodplain prone to channel migration and the landscape more susceptible to erosion

acoustic fluidization and the extraordinary mobility of sturzstroms 1 sturzstroms are a rare category of rock avalanche that travel vast horizontal distances with only a comparatively small vertical drop in height their extraordinary mobility appears to be a consequence of sustained fluid like behavior during motion which persists even for driving stresses well below those normally associated with granular flows one mechanism that may explain this temporary increase in the mobility of rock debris is acoustic fluidization where transient high frequency pressure fluctuations generated during the initial collapse and subsequent flow of a mass of rock debris may locally relieve overburden stresses in the rock mass and thus reduce the frictional resistance to slip between fragments in this paper we develop the acoustic fluidization model for the mechanics of sturzstroms and discuss the conditions under which this process may sustain fluid like flow of large rock avalanches at low driving stresses

massive ice avalanches on iapetus mobilized by friction reduction during flash heating the great distance travelled by long runout landslides observed previously on the earth and mars requires a mechanism of friction reduction identification and analysis of long runout landslides on saturn s moon iapetus suggests that the iapetian landslides are enabled by flash heating of the icy sliding surface

martian landslides in valles marineris wet or dry the objective of this paper is to determine whether martian landslides in valles marineris were wet or dry and place constraints on the availability of liquid water in valles marineris during the amazonian when the landslides occurred we thus statistically compare the power law relationship between the volume and runout distance of landslides on earth with those in valles marineris mars the exponent of the power law for martian landslides is similar to that for dry landslides and volcanic flows on earth and differs significantly from wet debris flows on earth the constant of proportionality in the observed power law relationship for martian flows is linearly proportional to gravity as predicted from physical modeling of dry flows in which the dissipation occurs in a layer of uniform thickness conversion of gravitational potential energy to heat is insufficient to generate more than a few weight percent of liquid water in the landslide we thus conclude that water did not significantly influence the dynamics of landslides in valles marineris this implies predominantly dry conditions in valles marineris during the amazonian

mid holocene sub blanket peat alluvia and sediment sources in the upper liffey valley co wicklow ireland a recently exposed section across a rst order valley buried beneath the regional blanket peat on hillside slopes in the upper liffey valley co wicklow is described the section shows two alluvia within a shallow valley form underlain by an extensive boulder and stone line over regional till and weathered granite 14c dates from wood in the alluvia indicate the older alluvium to have formed between 4324 53 bp and 4126 45 bp and the younger between 3217 53 bp and 2975 53 bp the basal layer of the overlying peat yielded a date of 2208 61 bp the younger alluvium shows the effects of soil paludi cation prior to the peat expansion dated pollen analyses elsewhere in the upper catchment con rm the spread of blanket peat over most areas above 350 m after 4000 3600 bp the buried valley was contributing sediments to the mid holocene oodplains in the upper liffey valley prior to the extension of blanket peat over the catchment after which sediment yields from it and the other catchment slopes declined copyright 2003 john wiley sons ltd

landslides on charon abstract we investigated five large landslides identified in the serenity chasma region of charon the identification of these landslides involved a search for these features in images taken by cameras onboard the new horizons spacecraft various landslide properties were analyzed based on their morphologies using a digital terrain model of the region we found that landslides are confined to the walls of the large normal fault scarps that make up serenity chasma based on extensive landslide runout lengths l relative to their drop heights h we classified these features as long runout landslides by analyzing their geometries we estimated the friction coefficients of the landslide material h l to be between 0 15 to 0 31 and the runout efficiencies l h to be between 3 2 and 6 8 we also estimated that the specific energy released during landslide motion ranged from 0 8 to 1 3 kj kg 1 these amounts of energy were too low to have generated significant melt around landslide particles

post glacial fluvial response and landform development in the upper muskegon river valley in north central lower michigan u s a article i nfo this study focuses on the upper part of the muskegon river system in north central lower michigan and is the first to reconstruct the post glacial history of fluvial landform development in the core of north america s great lakes region results indicate that the upper muskegon river valley contains four alluvial terraces and numerous paleomeanders radiocarbon dating of peats within these old channels provides a good chronology for stream behavior and landform development the t 4 terrace is a paired pleistocene outwash lacustrine surface that probably formed about 12 500 years ago the t 3 terrace is a fill strath surface that was cut between about 12 000 and perhaps 9500 years ago the geometry of macromeanders on this surface suggests that stream discharge was 8 times greater than during the holocene the pleistocene holocene transition is marked by a major period of downcutting that likely began as the climate warmed dried and sediment yield diminished this period of downcutting potentially lasted through the drier middle holocene creating a 6 m high escarpment in the valley the muskegon river then began to aggrade when the climate became wetter subsequently the river again incised creating the paired t 2 terrace about 3400 years ago when the climate became still wetter t 2 paleomeanders indicate that stream discharge at this time was consistent with the modern river in the past 2500 years the stream has constructed a poorly defined complex of t 1 terraces these surfaces likely formed due to complex response associated with more variable climate this study demonstrates that the upper muskegon river has a similar post glacial history as streams on deglacial and periglacial landscapes elsewhere in the world

origin of drumlins on the floor of lake ontario and in upper new york state abstract upper new york state usa contains one of the largest drumlin fields 12 000 km2 on the north america continent consisting of some 10 000 drumlins located between lake ontario in the north and the finger lakes drumlin like bedforms have also recently been discovered in deep water 200 m on the nearby floor of the rochester basin in lake ontario the new york state drumlin field was produced under the laurentide ice sheet 18 000 years ago when it extended southwards to terminate against the allegheny plateau outcrops of drumlin cores exposed by erosion along the lake ontario shoreline provide windows into the stratigraphy and sedimentology of the northern part of the field sedimentological description of 10 coastal drumlin cores combined with quantitative morphometric analysis of 1487 drumlins shows that they are the product of subglacial erosion of till sheets separated by glaciolacustrine deposits a two phase subglacial model for drumlin formation is suggested consisting of initial aggradation of extensive till deposits during ice advance followed by erosion and streamlining possibly accompanying stillstand of the ice margin and building of moraines systematic changes in drumlin morphometry and spacing are evident ranging from small numbers 60 closely spaced ovoid drumlins l w ratios between 1 and 3 drumlin shape appears to be systematically related to sediment thickness available for erosional streamlining elongate spindle forms occur on the crests and lee sides of bedrock escarpments where sediment cover is thin larger ovoid drumlins occur in topographic depressions where sediment thickness is greater offshore streamlined forms on the floor of the deep water rochester basin in lake ontario have long axes at right angles to the trend of onshore drumlins these are composed of rock rock drumlins and have an orientation structurally controlled by a newly identified inlier of proterozoic grenville province metasediments

drop height and volume control the mobility of long runout landslides on the earth and mars long runout landslides are landslides with volumes of 105 m3 or more which move much farther from their source than expected the observation that martian landslides are generally less mobile than terrestrial landslides offers important evidence regarding the mechanism responsible for the high mobility of long runout landslides here we simulate landslides as granular flow using a soft particle discrete element model we show that while surface gravity plays a negligible role observed differences in fall height naturally reproduce the observed differences in mobility of martian and terrestrial landslides we also demonstrate that landslides on iapetus may fit this trend our simulations do not include any fluid and indicate that a mechanism similar to acoustic fluidization can explain the high mobility of long runout landslides this implies that long runout landslides on mars should not be considered as evidence for ice saturated clays or liquid water

dating of post glacial landforms in the central howgills little is known of holocene landform development in upland britain this paper describes a site at middle langdale in the howgill fells of cumbria where large but now stabilized and inactive gullies cut through periglacial material at the base of the gullies large debris cones have buried earlier alluvial sediments on the valley floor on these sediments and buried by the debris cones is a well developed organic soil from which two 14c dates have been obtained in an attempt to estimate the age range of the soil these dates range from 2580 55 years bp for the fine particulate fraction from the base of the organic horizon to 940 95 years bp for fossil rootlets from the uppermost organic layer immediately below the overlying debris cones the pollen evidence suggests that the valley floor site was initially dominated by alder carr and later by a juncus marsh with birch alder and hazel nearby the pollen from the surrounding upland area suggests woodland on the valley sides dominated by oak and elm that was later replaced by a more open environment rich in heath species and in which disturbed ground species were present the magnetic evidence indicates a stable local environment during soil formation but shows a sudden inwash of unweathered debris at the top of the buried soil the evidence suggests that the valley floor was geomorphologically stable throughout the period of soil formation although there was a local change in valley floor vegetation and a reduction of woodland cover on the valley sides at sometime during the period the evidence then points to major geomorphological changes a wave of soil erosion gully development and debris cone deposition perhaps following the scandinavian introduction of sheep farming in the tenth century a d

the reduction of friction in long runout landslides as an emergent phenomenon campbell et al 1995 modeled long runout landslides as granular flow using a soft particle code their model essentially simulates landslides from first principles and although no fluid or obvious mechanism for reduction of friction is included the model successfully reproduced many field observations of landslides e g the preservation of source stratigraphy in the final slide mass and a decreasing effective friction with increasing slide volume we extend the work of campbell et al 1995 with a focus on the mechanism that reduces friction in these slides we find sliding preferentially occurs when the overburden is relieved by pressure variations in the slide further analysis shows that our results are very similar to the predictions of the acoustic fluidization hypothesis moreover we determine that for long runout landslides the wavelength of vibrations associated with acoustic fluidization is determined by the size of the rock fragments in the slide

river response to rapid holocene environmental change evidence and explanation in british catchments macklin m g jones a f lewin j 2010 river response to rapid holocene environmental change evidence and explanation in british catchments quaternary science reviews 29 13 14 1555 1576 sponsorship welsh assembly government and the higher education funding council for wales for funding this study through its support of the centre for catchment and coastal research at aberystwyth university

holocene alluvial fan and terrace formation in the bowland fells northwest england in the bowland fells lancashire northwest england in the headwater valleys of the hodder river system is a suite of holocene fluvial landforms debris cones and alluvial fans at tributary junctions and river terraces along the main valleys post date late pleistocene forms and pre date the modern valley floor alluvial forms eight 14c dates from wood samples incorporated within the terrace and fan deposits have allowed two main phases of holocene erosion to be identified with debris cone fan deposition taking place after c 5400 bp but before c 1900 bp and again at c 900 bp some of the fans and cones are complex with deposits attributable to both phases others are simple and attributable only to the later phase in the headwaters an upper terrace at c 5400 bp pre dates the cones and a lower terrace is contemporaneous with the first debris cone phase lower downvalley the youngest of three terraces date from c 5000 bp or earlier indicating that the sequence is less complex downstream

self lubrication for long runout landslides examination by computer simulation this paper describes the use of a discrete particle computer simulation to test whether the apparent low friction exhibited by long runout landslides could be explained in terms of simple granular mechanics the flow structure consists of an active basal shear zone supporting the majority of the landslide which travels as a relatively solid plug the observed runout appears to depend on the total energy dissipation which is a trade off between 1 the inelasticity of the particles which governs the energy dissipated in each event and 2 the size of the dissipating shear zone which governs the number of particles that are actively dissipating energy very inelastic particles quickly dissipate the work performed at boundaries and result in thin dissipative zones as a result these two factors balance and the runout is nearly independent of particle inelasticity along the same lines increasing the boundary roughness was found to increase the size of the dissipative shear zone and markedly decrease the runout also a distribution of particle sizes destroyed ordered structures within the body which once again increases the dissipation and decreases the runout unfortunately the simulations also indicate that the runout should be independent of the depth of the flow and thus cannot account for the observed volumetric effect on runout

holocene evolution of a lowland scottish landscape kirkpatrick fleming part iii fluvial history mapping and radiocarbon dating of fluvial terrace fragments along the greater length of the kirtle water resulted in the definition of five major terrace surfaces correlations with proxy records of climate change part i and anthropogenic activity part ii are made to understand causal mechanisms in fluvial behaviour the limitations of such correlations are emphasized the highest terrace kirtle i is thought to be of devensian lateglacial age the remaining four are of holocene age an early holocene gravel aggradation kirtle ii may have been sustained from c 7250 14c years bc until close to c 455 cal bc the establishment of alnus on floodplains may have led to channel stability incision after c 3250 cal bc may have been due to greater discharges at a time of deteriorating climate terrace kirtle iii is undated prior to aggradation of terrace kirtle iv beginning at around cal ad 300 a period of lowered fluvial activity and floodplain stability is recorded from c 850 cal bc anthropoge

holocene debris cone evolution in glen etive western grampian highlands scotland stratigraphic investigations radiocarbon dating of buried soils and pollen analyses were employed to reconstruct the history of development of a fluvially reworked debris cone in glen etive paraglacial aggradation of debris flow deposits resulted in cone formation between c 10000 yr b p and c 4000 yr b p until supplies of sediment from upslope were effectively exhausted and debris flow activity ceased there ensued a prolonged period of stability and soil development on the cone surface this ended sometime after c 550 yr b p when human interference including burning resulted in destruction of the natural vegetation cover and triggered fluvial incision and the development of an alluvial fan of reworked sediment that buried the lower part of the debris cone the wider implications of these findings are discussed

agro industrial alluvium in the swale catchment northern england as an event marker for the anthropocene foulds s a macklin m g brewer p a 2013 agro industrial alluvium in the swale catchment northern england as an event marker for the anthropocene the holocene 23 4 587 602

hairpin erosional marks horseshoe vortices and subglacial erosion abstract crescentic erosional marks wrapped around obstacles and extending into straight grooves are termed hairpin erosional marks they are u shaped to semi circular in cross section are deepest around the upstream shoulders of the obstacles and range over seven orders of magnitude in scale some are asymmetrical with one groove better developed than the other the straight grooves may broaden and shallow rapidly in the downflow direction upstream grooves merge with rather than cross downstream crescentic marks grooves are distinct from glacial abrasion forms and many are not striated hairpin erosional marks are interpreted as being products of scour by horseshoe vortices in turbulent fluids this interpretation is supported by the close similarity of these marks to scours produced experimentally and in nature by horseshoe vortices estimated reynolds numbers show that such vortices are probable around obstacles in wind and flowing water but are extremely unlikely in ice aeolian hairpin erosional marks related to yardangs are illustrated to support this conclusion the surface texture cross sectional shapes and spatial patterns of hairpin erosional marks also discount formation by ice a model for the evolution of isolated erosional drumlins from an initial field of hairpin erosional marks extends earlier research on a meltwater hypothesis for drumlins

mediaeval lead pollution in the river ouse at york england the city of york in northern england has a long history of being flooded by the river ouse excavations of a 9 m sedimentary profile were carried out by the york archaeological trust on the site of a pumping station associated with a flood prevention scheme at north street on the south west bank of the river ouse this profile records evidence of human activity and episodic river sedimentation over a period from the 2nd to the 14th century ad anthropogenic materials in the profile include waterfront timber and wattle structures and dumps of organic domestic debris and industrial waste evidence of historic floods is preserved in interleaved alluvial deposits this study reports on the degree of lead pb contamination at the site from roman to mediaeval times and the sources of both alluvial and manufactured lead deposited in the profile archaeological sedimentological geochemical and mineralogical evidence suggest that yorkshire dales mining activity during the 9th 13th centuries ad may have both directly and indirectly caused lead contamination of the alluvial deposits at north street

non synchronous response of adjacent floodplain systems to holocene environmental change abstract two adjacent upland floodplains are compared to establish the local response of floodplains to environmental change radiocarbon dating the analysis of sedimentary exposures terrace mapping aerial photography and archaeological evidence are used to examine late quaternary valley fill sediments on the afon tanat and the afon vymwy in the upper severn basin wales uk the alluvial stratigraphy of the two floodplain systems consists of late devensian last glacial fluvio glacial sediments at the valley margins deposited under a braided outwash river regime holocene age terraces with floodplain and palaeochannel deposits composed of gravels overlain by silty sands are inset into this older unit and were formed by meandering fluvial channel systems a combination of field and laboratory data demonstrates that from the mid late holocene the two floodplain systems had divergent development the afon vyrnwy has remained vertically stable for the last ca 4000 yrs whereas the adjacent afon tanat continued to be vertically and laterally active both floodplain systems have been affected by late quaternary climatic fluctuations and anthropogenic activity from the bronze age to the roman period but local geomorphic gradient controls combined with a possibly greater focus of anthropogenic activity in the tanat catchment may explain the differential evolution of the two systems the data demonstrate that multiple reach scale studies are essential for revealing significant stages in the chronology and historical development of fluvial systems

influence of the scar geometry on landslide dynamics and deposits application to martian landslides received 24 january 2011 revised 23 june 2011 accepted 30 june 2011 published 4 october 2011 1 landslides dynamics prediction remains difficult in spite of a considerable number of studies the runout distance is widely used in analysis of landslide dynamics and in the calibration of the rheological parameters involved in numerical modeling however the unknown impact of the significant uncertainty in the shape of the initial released mass on the runoutdistanceandontheoverallshapeofthedepositraisesquestionsabouttherelevanceof these approaches the impact of the initial scar geometry on flow and distribution of the deposits is studied here using satellite data and numerical modeling of theoretical landslides and martian landslides informed by geomorphological analysis by varying the initial scar geometry from spoon shaped to steep wall geometry our results show that the runout distance is a very robust parameter that is only slightly affected by the change in the geometry of the initial scar on the contrary the lateral extent of the deposit is shown to be controlled by the scar geometry providing unique insights into the initial landsliding conditionsonmarsandmakesitpossibletoaccuratelyrecoverthevolumeinitiallyinvolved an essential ingredient for volume balance calculation a feedback analysis of valles marineris landslides can be drawn showing good agreement between numerical results and geomorphological analysis the geometry of the initial scar inferred from numerical modeling is strongly correlated with the regional tectonic history in valles marineris area

long runout landslides and the long lasting effects of early water activity on mars reply long runout subaerial landslides 50 km are rare on earth but are common features shaping mars valles marineris troughs in this study we investigated the highly debated emplacement mechanisms of these martian landslides by combining spectral and satellite image analyses our results suggest that hydrated silicates played a decisive role in facilitating landslide transport by lubricating the basal sliding zone this new understanding implies that clay minerals generated as a result of water rock interactions in the noachian and hesperian 4 1 3 3 ga exert a long lasting influence on geomorphic processes that shape the surface of the planet

flood alluviation and entrenchment holocene valley floor development and transformation in the british uplands the morphology sedimentary properties and sequence of recent coarse grained flood deposits and earlier holocene alluvial fills were investigated in thinhope burn a small 12 km2 catchment in the northern pennine uplands northern england twenty one large flood events are recorded by distinctive cobble boulder bars sheets and splays and boulder berms and lobes lichenometric analysis showed that all but one of these floods dated from the mid eighteenth century the timing of large floods between 1766 and 1960 corresponds with major hydroclimatic trends evident in northern britain and northwest europe over this period discharge estimates suggest that flood magnitudes have decreased since the mid eighteenth century channel and flood plain metamorphosis in late roman times and in the eighteenth century following major valley floor entrenchment locally as much as 8 m would appear to have been caused by increased runoff and flood magnitude this was linked to a shift to a wetter climate with flow augmented by iron age and roman woodland clearance and drainage of the catchment in more recent times results from this study suggest that current models of longer term holocene and pleistocene valley floor development in the british uplands may need to be re evaluated

comment on the reduction of friction in long runout landslides as an emergent phenomenon by brandon c johnson et al results from a highly idealized 2 d computational model indicate that dynamic normal stress rarefactions might cause friction reduction in long runout landslides johnson et al 2016 but the physical relevance of the idealized dynamics has not been confirmed by experimental tests more importantly the model results provide no evidence that refutes alternative hypotheses about friction reduction mechanisms one alternative hypothesis which is strongly supported by field evidence experimental data and the predictions of a well constrained computational model involves development of high pore fluid pressures in deforming landslide material or overridden bed material however no scientific basis exists for concluding that a universal mechanism is responsible for friction reduction in all long runout landslides

fluvial sediments correlations and palaeoenvironmental reconstruction the development of robust radiocarbon chronologies abstract multiple sequences of radiocarbon dates extracted from organic materials are increasingly being used to provide robust chronologies for landscape development particularly the timing and correlation of significant climatic and process events whilst the validity of using such frameworks in sedimentary environments such as lake basins and raised bogs has been the focus of much attention such debates have not extended to fluvial systems using examples from three lowland vertically accreting river valleys in east anglia uk this paper assesses the robustness of their associated radiocarbon chronologies by assessing the contrasting age estimates that are obtained by dating different parts of the same organic sample humic humin and plant macrofossils at a variety of stratigraphic levels overall the humin and humic acid fraction results were statistically consistent whilst the plant macrofossil remains were found to be of a slightly younger age in these examples it is argued that the younger ages appear to be the result of phragmites common reed roots pushing plant macrossils through the sedimentary sequence or opening up voids for material to fall through although studies in lacustrine and mire environments suggest alternative explanations may also be possible whichever explanation is preferred this study demonstrates clearly that the complexity of valley floor stratigraphy and processes is such that using single radiocarbon dates whether ams or bulk samples to reconstruct chronologies of geomorphic system response may need to be refined and subjected to the same level of assessment that has been applied in other sedimentary systems

the age of alluvial fan deposition at a site in the southern uplands of scotland the age of a large alluvial fan debouching onto the valley floor of the river tweed in southern scotland and the sequence of events relating to this are investigated using geomorphological sedimentological palynological archaeological and radiocarbon dating evidence prior to fan deposition the tweed valley floor seems to have been covered by a wooded peat at a time of low fluvial activity the fan commenced deposition in the 11th century ad and appears to have been a local event the tweed showing no response to this accelerated sedimentation later perhaps 200 years later the tweed commenced overbank deposition of the only flandrian terrace preserved local proxy data are examined in order to define the causes of these events but difficulties in temporal correlation despite the good resolution of the radiocarbon chronology mean that the causes of these events remain unknown

rheological constraints on martian landslides we use a dynamic finite difference model to simulate martian landslides in the valles marineris canyon system and olympus mons aureole using three different modal rheologies frictional bingham and power law the frictional and bingham modes are applied individually fluidized rheology is treated as a combination of frictional and power law modes general fluidization can include pore pressure contributions whereas acoustic fluidization does not we find that general fluidization most often produces slides that best match landslide geometry in the valles marineris this implies that some amount of supporting liquid or gas was present in the material during failure the profile of the olympus mons aureole is not well matched by any landslide model suggesting an alternative genesis in contrast acoustic fluidization produces the best match for a lunar slide a result anticipated for dry crust with no overlying atmosphere the presence of pressurized fluid during valles marineris landsliding may be due to liquid water beneath a thin cryosphere 1 2 km or flash sublimation of co2

valles marineris mars wet debris flows and ground ice abstract detailed study of the valles marineris equatorial troughs suggests that the landslides in that area contained water and probably were gigantic wet debris flows one landslide complex generated a channel that has several bends and extends for 250 km further support for water or ice in debris masses includes rounded flow lobes and transport of some slide masses in the direction of the local topographic slope differences in speed and emplacement efficiency between martian and terrestrial landslides can be attributed to the entrainment of volatiles on mars but they can also be explained by other mechanisms support that the wall rock contained water comes from the following observations 1 the water within the landslide debris must have been derived from wall rock 2 debris appears to have been transported through tributary canyons 3 locally channels emerged from the canyons 4 the wall rock apprarently disintegrated and flowed easily and 5 fault zones within the troughs are unusually resistant to erosion the study further suggests that in the equatorial region of mars material below depths of 400 800 m was not desiccated during the time of landslide activity within the last billion years of martian history therefore the martian ground water or groundice reservoir if not a relic from ancient times must have been replenished

terraced fills of pleistocene and holocene age in the rheidol valley wales the legacy of repeated pleistocene glaciations has endowed many welsh river valleys with locally thick successions of glacial and alluvial sediments investigations of a well preserved flight of terraced sediments with good exposures at capel bangor on the afon rheidol mid wales has allowed its quaternary valley fill stratigraphy to be examined in detail study has revealed five terraced fills consisting of seven distinct sedimentary units these range from late devensian ice contact and ice marginal deposits to holocene high sinuosity stream sediments with episodes of man induced accelerated deposition of fine grained alluvium and to aggradation and subsequent incision associated with historic metal mining examination of general sedimentary properties e g granulometry sedimentary structures terrace surface morphology show both differences in the pattern and controls of deposition and also progressive changes over late devensian and holocene times the sediments of the rheidol valley record the response and subsequent recovery of a drainage basin to glaciation and the increasing influence of man on sediment yields channel processes and sediment quality

holocene landscape change at carn dubh near pitlochry perthshire scotland detailed palynological analyses including pollen preservation and charcoal counts and sedimentological analyses loss on ignition percentage dry weight dry bulk density and humification supported by 15 14c dates were applied to a small upland 350 m od peat basin near pitlochry east central grampians scotland stratigraphical analyses and radiocarbon dating were also undertaken on the valley peat surrounding the basin organic sediment began to accumulate in the basin and on the valley floor at ca 9800 yr bp recurrence surfaces within the valley floor peat correlate with the end of a trend to increased aridity in the deep basin from 8900 to 8500 yr bp pine may have colonised the hills with birch before the migration of hazel at 9150 yr bp from around 8000 yr bp elm grew on the base rich soils alder may have been present by 7000 yr bp but it did not expand until immediately after the first major anthropogenic disturbance at 4800 yr bp above 8000 yr bp silt was commonly deposited in the basin by streams but several phases of exceptionally intense inwashing are identified and at least two of these correlate with periods of increased precipitation grazing pressure during the elm decline marks the beginning of a long history of generally low intensity pastoralism interspersed with periods of heightened anthropogenic activity

reply to the comment by h a j russell on converging ice streams a new paradigm for reconstructions of the laurentide ice sheet in southern ontario and deposition of the oak ridges moraine 1

river entrenchment and terrace formation in the uk holocene abstract a meta analysis of a large database of 14c dated fluvial units is used to assess the chronology and controls of episodic holocene river entrenchment and terrace formation in the uk most holocene terraces are of a fill cut type developed in pleistocene sediments in places now reaching down to pre holocene bedrock holocene terraces are widespread in higher relief areas of the uk and peripheral higher energy rivers and include up to 7 levels in some valley floor reaches using 14c constrained data sub sets for incision episodes the onset vertical ranges formation times and rates of entrenchment are examined together with geographical distributions the height range of terrace separation is relatively small 0 5 3 5 m with a long term averaged incision rate over the late and mid holocene of 0 43 0 5 0 67 0 7 and 0 81 m ka in the tweed rheidol severn ouse and ribble catchments and a regional similarity in the scale of incision events the periods 4200 3700 3100 2900 2100 1900 1800 1500 cal bp and most notably the last 1000 years with prominent peaks at 900 800 and 700 600 cal bp were times of accelerated incision it appears likely that extreme flood events triggered the formation of incision slots rather than entrenchment being a direct response to glacio tectonic uplift or the result of incremental valley floor lowering by combined incision and lateral reworking river entrenchment has also been rapid in recent centuries reflecting the coupling of extreme events with anthropogenic effects on catchment hydrology incision results in changes of river channel flood power and overbank flood extent and improved data on the long term and large scale vertical tendency of uk rivers are needed for flood risk management purposes

a sensitive high resolution record of late holocene climatic change from a raised bog in northern england proxy climatic data in the form of plant macrofossils have been analysed from a 5 m core from bolton fell moss cumbria uk detailed analysis of peat from the upper 50 cm of this core is used to demonstrate a strong correlation between changes in the relative proportion of taxa and known climatic changes over the last 1000 years the record of changes in bog vegetation contained within the peat profile is used to reconstruct changes in bog surface wetness for the latter half of the holocene as bog surface wetness is directly controlled by the prevailing climatic conditions this reconstruction can be viewed as a proxy climate record twelve radiocarbon age estimates on the 5m core suggest that between 50 and 500 cm peat accumulated at a relatively constant rate of 12 4 yr cm 1 the regular sampling intervals thus provide a time series of past bog surface wetness spectral analyses of this series indicates that wetness changes are cyclic with a ca 800 year periodicity

rock avalanche mobility the role of path material abstract rock avalanches are high velocity flows of fragmented rock that can dramatically alter landscapes and impact people and infrastructure far from their source these catastrophic events have been studied for over a century however a consensus regarding the mechanism s that govern their motion has yet to emerge this work details the results of the back analysis of 45 rock avalanche case histories using a semi empirical runout model that simulates motion over 3d terrain these simulations account for topographic effects and bulk basal shear resistance variation during motion for a subset of the cases we find that a volume dependent mechanism appears to influence basal resistance in the source zone however once the material has vacated the source zone our results suggest that the character of the path material strongly controls mobility and appears to dominate over other potentially volume dependent mechanisms that may also be at work the results presented in this paper support the longstanding hypothesis that the interaction of flowing debris with the underlying substrate is an important consideration in rock avalanche runout prediction and that this mechanism warrants further research

geomorphological evidence for ground ice on dwarf planet ceres despite evidence for an ice rich outer shell little water ice has been observed on the surface of ceres lobate morphologies observed on ceres that are increasingly prevalent towards the dwarf planet s poles are consistent with ice rich flows

architectural element analysis applied to glacial deposits internal geometry of a late pleistocene till sheet ontario canada deposits left by continental ice sheets are characterized by sedimentological complexity and stratigraphic heterogeneity but stratigraphic descriptions of such deposits and resulting first generation facies models are still based primarily on one or two dimensional borehole or outcrop data reconstruction of depositional environments hydrogeological investigations of pleistocene glacial deposits and hydrocarbon exploration in pre pleistocene glaciated basin fills require a more detailed understanding of the form and heterogeneity of lithofacies sequences in three dimensions architectural element analysis is used widely by sedimentologists for categorizing internal stratigraphic heterogeneity in sandstones particularly those of fluvial origin this paper demonstrates the first application of architectural element analysis to glacial deposits such as tills outcrop borehole and a broad range of subsurface geophysical data were collected from a thick 60 m till sheet present across an 80 km 2 study area near toronto canada the till sheet is not homogeneous but is composed of three distinct architectural elements and associated lithofacies viz diamict elements interbeds of subglaciofluvial sediments and glaciotectonically deformed zones application of architectural element analysis to these subglacial strata provides insights into the origin of drumlin bedforms and subglacial processes below the laurentide ice sheet and creates a framework for understanding ground water and contaminant movement in underlying aquifers

holocene alluviation and land use change on callaly moor northumberland england archaeological survey and palaeoenvironmental investigations in coe burn callaly moor northumberland have examined the chronology and nature of prehistoric and historic land use change in a small upland river catchment these studies have revealed an intensively used landscape with evidence of late neolithic to bronze age medieval and post medieval land use and settlement two episodes of valley floor alluviation are identified and dated to the middle late bronze age and post medieval periods magnetic mineral and geochemical analyses of fine sediments from the older alluvial fill show it to contain a high proportion of topsoil which is believed to have been produced by soil erosion resulting from bronze age tree clearance and cultivation deposition of the younger alluvial fill post ad 1500 was associated with the inwash of relatively unweathered bedrock generated by coal mining in the catchment it is demonstrated that by integrating archaeological field survey with off site palaeoenvironmental investigations a much fuller picture of human activity and land use change has emerged than otherwise would have been the case studies of this type may be particularly useful in other upland river catchments where archaeological survival is limited or poor

water sheet outburst floods from the laurentide ice sheet field evidence and a theoretical model support the concept that during wisconsinan glaciation subglacial water sheet outburst floods issued from a large subglacial lake located in the hudson bay ba

a quantitative soil stratigraphic approach to the correlation and dating of post glacial river terraces in glen feshie western cairngorms little is known about holocene river terrace development in upland scottish valleys interpretation of many of the terrace sequences previously suggested to have been formed by meltwaters either from the last scottish ice sheet or the loch lomond advance has generally been based on morphological data in this paper an alternative approach to the traditional height based method of terrace correlation and dating is presented using data from glen feshie western cairngorms terrace fragments are numerically classified and objectively grouped using quantitative soil stratigraphic data principal components analysis is used to both quantify pedological data and separate temporal trends in the data from variance due to local site factors the scores on the temporal component are used to derive soil stratigraphic units developed on the surficial sediments of the glen feshie terraces by grouping soil sites using a hierarchical clustering technique this provides evidence for at least five soil stratigraphic units developed on the fluvial surfaces various methods of absolute dating control permits association of these surfaces with five phases of terrace development these are placed tentatively at 13 000 10 000 3600 1000 and 80 radiocarbon years b p suggesting at least three phases of valley floor incision in glen feshie during the late holocene

optically stimulated luminescence osl dating of loessic sediments and cemented scree in northwest england optically stimulated luminescence osl dates are reported for silts and very fine sands believed to be loessic sediments from northwest england at three sites loessic sediments were initially interpreted as primary aeolian deposits and at two other sites as loess incorporated into the matrix of cemented scree however the results of osl dating indicate a more complex pattern of accumulation than originally hypothesized and have prompted reconsideration of these materials whatever the process es and underlying cause s it is evident that significant amounts of soil erosion occurred on the limestone uplands earlier than previously thought all but one of the ages fall entirely within the holocene period and suggest that these deposits contain reworked rather than primary loess four of the five sites are characterized by non gaussian dose distributions and consequently equivalent doses have been estimated using a range of appropriate age models the implications of differences in the ages derived f

the evolution of the samaoding paleolandslide river blocking event at the upstream reaches of the jinsha river tibetan plateau abstract a large number of landslides have occurred in the upstream reaches of the jinsha river tibetan plateau due to the intensity of tectonic movement in the area remote sensing and field investigation indicate that one of them the samaoding paleolandslide previously blocked the river various river blocking phenomena are well preserved including the old landslide dam and deposits fluvial sediments and hydrostatic sandy sediment to better understand the evolution of the samaoding landslide the authors carried out thermoluminescence tl dating and numerical simulations the tl analysis shows that the landslide occurred at 10 6 0 5 ka bp discrete element method dem simulation of the landslide based on landform restoration provided results that are consistent with field observations the simulation indicates that the entire landslide process lasted for 80 s and the sliding mass reached a maximum velocity of 64 m s the landslide formed a landslide dam with a length of 1900 m a width of 600 m and a depth of 200 m the simulation results show that the level of the riverbed at that the time of the landslide was at least 25 m higher than it is today on the combined basis of the simulation results and field observations the authors propose explanation that the following valley evolution sequence occurred after river blocking the landslide dam experienced flood overtopping and then was eroded until it had mostly had been transported away by river flow and the river then rapidly incised the bedrock to form the present day landform based on the field investigations the authors summarize the failure mechanism of steep inclined antidip rockslides and found that tectonics play an important role in the formation of landslide dams or trigger of landslides and the failure of landslide dams in an active tectonic environment of tibetan plateau

large mass movements on callisto galileo images reveal the presence of mass movement deposits within impact craters on callisto eleven such deposits were found in 830 candidate craters imaged at sufficient resolutions 86 280 m pixel for their identification all of the deposits are located within impact craters and their sources appear to be crater wall material the morphologies of the callistan deposits are similar to terrestrial mass movements and rock glaciers rock glaciers involve ductile flow of ice and rock but in the callistan environment water ice is likely to undergo brittle deformation consequently rock glaciers are unlikely analogs for the features on callisto three morphologies are observed one blocky one slump like and nine lobate deposits blocky deposits are characterized by massive blocks on the crater floor while slump like deposits appear as debris piles along the base of the crater wall lobate deposits are 1 7 9 9 km long average 90 m in thickness and have tapered or semicircular terminations callistan lobate deposits are morphologically similar to rapidly emplaced dry rock avalanches on earth their significant thickness and steep frontal margins suggest that they may have behaved similarly to bingham plastic material with a critical yield strength the callistan deposits have yield strengths similar to those estimated for terrestrial dry rock avalanches the blocky deposit appears similar to terrestrial block glide deposits in which large blocks detach and slide downslope individual blocks within the blocky deposits may be up to 1 km across and stand 30 60 m high callistan slump like deposits are similar to terrestrial slumps which fail along rotational planes mass movements on callisto are not confined to craters they have also been observed along the base of scarps knobs and ridges three of the callistan deposits may have been impact triggered because of the proximity of an impact crater near the source first order analyses of the ground force generated by impacts show that two of the candidate deposits are capable of being impact triggered the callistan mass movements are probably set into motion by a combination of sublimation of ice which undermines a near surface layer of lag material and seismic triggering associated with nearby impact events

origin of mountains on io by thrust faulting and large scale mass movements voyager stereoimages of euboea montes io indicate that this mountain formed when a large crustal block was uplifted 10 5 kilometers and tilted by approximately 6 degrees uplift triggered a massive slope failure on the northwest flank forming one of the largest debris aprons in the solar system this slope failure probably involved relatively unconsolidated layers totaling approximately 2 kilometers in thickness overlying a rigid crust or lithosphere at least 11 kilometers thick mountain formation on io may involve localized deep rooted thrust faulting and block rotation due to compression at depth induced during vertical recycling of io s crust

large scale landslide simulations global deformation velocities and basal friction the cause of the apparent small friction exhibited by long runout landslides has long been speculated upon in an attempt to provide some insight into the matter this paper describes results obtained from a discrete particle computer simulation of landslides composed of up to 1 000 000 two dimensional discs while simplified the results show many of the characteristics of field data the volumetric effect on runout preserved strata etc and with allowances made for the two dimensional nature of the simulation the runouts compare well with those of actual landslides the results challenge the current view that landslides travel as a nearly solid block riding atop a low friction basal layer instead they show that the mass is completely shearing and indicate that the apparent friction coefficient is an increasing function of shear rate the volumetric effect can then be understood with all other conditions being equal different size slides appear to travel with nearly the same average velocity however as the larger landslides are thicker they experience smaller shear rates and correspondingly smaller fractional resistance

late quaternary river terrace development in the macgillycuddy s reeks southwest ireland abstract geomorphological sedimentological pedostratigraphical and palaeoecological analyses of fluvial and glacigenic deposits infilling the gaddagh valley macgillycuddy s reeks southwest ireland are used to elucidate the patterns and controls of late quaternary valley floor development in a 3 km reach of the catchment lying immediately downvalley of two mid basin lakes lough gouragh and lough callee a total of four holocene alluvial terraces terrace level tl 2 5 and a modern floodplain tl 6 have been identified and lie inset within a strath terrace comprising late quaternary midlandian till tl 1 the combination of mid basin lakes and flanking strath terraces acted to decouple the gaddagh channel from upper catchment and valley side debris sources shortly after regional deglaciation postglacial fluvial terrace development in the study reach has therefore occurred primarily in response to hydrological changes and reworking of local valley floor deposits rather than catchment wide debris supply changes pollen analyses of valley floor peat deposits interbedded with minerogenic alluvium indicate that anthropogenic disturbance of catchment tree cover had commenced by c a 1690 1450 cal bc and that the catchment was largely cleared of woodland by later prehistoric times major phases of incision and alluviation represented by terraces tl 3 5 however have been radiocarbon dated to the period after 250 530 cal ad and broadly correspond with holocene fluvial records elsewhere in the region upland britain and northwest europe although fluvial system responses to hydrological changes will have been promoted by anthropogenic disturbances of catchment vegetation cover the timing of late holocene incision and alluviation episodes are interpreted as reflecting enhanced flood frequencies and or magnitudes associated with late holocene climatic shifts in the gaddagh valley however we hypothesise that the headwater lakes lough gouragh and lough callee may also have exerted a critical control on the postglacial evolution of the valley floor in particular high magnitude flooding is likely to have been instrumental in valley floor entrenchment and formation of tl 3 tl 4 and tl 5 terraces

spatiotemporal evolution mineralogical composition and transport mechanisms of long runout landslides in valles marineris mars abstract long runout landslides with transport distances of 50 km are ubiquitous in valles marineris vm yet the transport mechanisms remain poorly understood four decades of studies reveal significant variation in landslide morphology and emplacement age but how these variations are related to landslide transport mechanisms is not clear in this study we address this question by conducting systematic geological mapping and compositional analysis of vm long runout landslides using high resolution mars reconnaissance orbiter imagery and spectral data our work shows that 1 a two zone morphological division i e an inner zone characterized by rotated blocks and an outer zone expressed by a thin sheet with a nearly flat surface characterizes all major vm landslides 2 landslide mobility is broadly dependent on landslide mass and 3 the maximum width of the outer zone and its transport distance are inversely related to the basal friction that was estimated from the surface slope angle of the outer zone our comprehensive compact reconnaissance imaging spectrometer for mars crism compositional analysis indicates that hydrated silicates are common in landslide outer zones and nearby trough floor deposits furthermore outer zones containing hydrated minerals are sometimes associated with longer runout and increased lateral spreading compared to those without detectable hydrated minerals finally with one exception we find that hydrated minerals are absent in the inner zones of the investigated vm landslides these results as whole suggest that hydrated minerals may have contributed to the magnitude of lateral spreading and long distance forward transport of major vm landslides

late devensian and holocene landscape change in the uplands of the isle of man abstract the late glacial and holocene geomorphology of the manx uplands has received scant attention in previous researches solifluction deposits and terraces provide the earliest evidence for geomorphic activity after deglaciation fluvial incision into drift choked valleys is correlated with the formation of the large mountain front alluvial fans that flank the manx uplands formation of these alluvial fans is constrained to 15 000 10 500 cal years bp by 14 c dates on organic deposits beneath and above the alluvial fan gravels alluvial fan and river terraces along four valleys postdate this incision optically stimulated luminescence osl and 14 c dating provide a tentative chronology for these landforms the higher terraces are late glacial fluvial surfaces that were probably occupied by rivers into the holocene incision during the late holocene led to the abandonment of the higher surfaces producing a suite of younger river terraces and alluvial fan surfaces independent dating constrains this fluvial activity to post bronze age 3500 2800 cal years bp increased human activity and climatic change during the late holocene are possible causes for this increased geomorphic activity

converging ice streams a new paradigm for reconstructions of the laurentide ice sheet in southern ontario and deposition of the oak ridges moraine geomorphometric analyses of high resolution 5 m digital elevation datasets shows that the greater toronto area and its immediate environs is built across the former till beds of two fast flowing ice streams the newly named the simcoe ice stream sis and the halton ice stream ois within the last laurentide ice sheet lis these formed during regional deglaciation sometime around 13 000 ybp and are directly analogous to fast flowing 3 km yr 1 ice streams in today s antarctic and greenland ice sheets their subglacial footprint in southern ontario consists of flow sets of highly elongated flow parallel till ridges up to 4 km in length and 100 m in width megascale glacial lineations msgls that converge on the oak ridges moraine orm from the north sis and south his orm is southern ontario s largest glacial landform extending from the niagara escarpment to kingston over some 160 km and was deposited as a series of en echelon glaciolacustrine fan deltas in a complexly evolving glaciolacustr

mass movement on vesta at steep scarps and crater rims the quadrangles av 11 and av 12 on vesta are located at the northern rim of the giant rheasilvia south polar impact basin the primary geologic units in av 11 and av 12 include material from the rheasilvia impact basin formation smooth material and different types of impact crater structures such as bimodal craters dark and bright crater ray material and dark ejecta material av 11 and av 12 exhibit almost the full range of mass wasting features observed on vesta such as slump blocks spur and gully morphologies and landslides within craters processes of collapse slope instability and seismically triggered events force material to slump down crater walls or scarps and produce landslides or rotational slump blocks the spur and gully morphology that is known to form on mars is also observed on vesta however on vesta this morphology formed under dry conditions

chronology and stratigraphy of late quaternary sediments in the konya basin turkey results from the kopal project abstract the late quaternary environmental history of the konya plain in south central turkey is used to examine sediment facies changes in a shallow non outlet basin which has experienced major climatically driven changes in lake extent two principal types of sedimentary archive are used to reconstruct a palaeoenvironmental record namely alluvial sequences on the carsamba alluvial fan and sediments from residual lakes the latter have been used to investigate broader climatic and vegetational histories via palaeolimnological techniques including pollen diatom and stable isotope analysis these changes are dated here by radiometric techniques including radiocarbon ams and conventional osl and u th chronological agreement is generally good between the different dating techniques although typically there is greatly reduced precision beyond ca 25 ka lake sediment cores investigated have basal ages beyond the range of 14c dating but contain hiatuses as a result of subsequent alternation between phases of lacustrine sedimentation and aeolian deflation in contrast to most deepwater non outlet lake systems the konya basin may have been occupied by a single extensive lake for as little as 10 of late quaternary time mainly around the time of the lgm this lake highstand was followed by an important arid interval in the absence of unbroken chronostratigraphic sequences palaeohydrological investigation of shallow non outlet lakes may require analysis of basin wide changes in sedimentation rather than reliance on single core records stratigraphic continuity in such sedimentary environments cannot be assumed and requires independent chronological control through radiometric dating

fluvial chronology and valley floor evolution of the upper bowmont valley borders region scotland two major fluvial terrace surfaces and four less significant surfaces are identified by aerial photographic interpretation field mapping and levelling on one c 2 km long reach of the upper bowmont water an upland stream draining the northern cheviot hills scotland the oldest terrace surface remains undated cartographic radiocarbon and palynological dating suggest that later terraces formed very recently within the last 250 years with the most prominent terrace fill having aggraded in the 18th century incision below this terrace surface is dated to approximately the end of the 18th century correlated with channel trenching at other sites in the region detailed palaeoecological and documentary evidence is used to examine whether climatic or land use changes might have instigated aggradation and a link with increased precipitation and flooding during part of the little ice age is suggested

mass spectrometric dating of flowstones from stump cross caverns and lancaster hole yorkshire palaeoclimate implications a terrestrial flowstone sequence 97 cm thick from stump cross caverns yorkshire has been dated by both mass spectrometric and alpha spectrometric 238u 234u 230th dating and is demonstrated to have been deposited predominantly during interstadial periods over the last 170 ka with no growth in periods of glaciation or within the oxygen isotope stage 5 interglacial growth also occurs within oxygen isotope stages 4 and 6 the former possibly correlating with interstadials recognised in high resolution ice and ocean core records comparison with the timing of growth of a mass spectrometrically dated lancaster hole flowstone also from the same region demonstrates only limited agreement these differences are due to two factors limiting deposition at stump cross flooding of the cave passage in warm periods and the development of continuous permafrost or glacier cover in periods of severe climatic deterioration deposition at lancaster hole was controlled by limitations in ground water supply rather than flooding of the cave passage the results presented here demonstrate that in addition to regional palaeoclimate factors local site conditions may limit speleothem growth we conclude that in future palaeoclimate studies the growth record from several coeval speleothem samples must be considered before a regional palaeoclimate interpretation can be made

sediment transmission and storage the implications for reconstructing landform development the late holocene last 3000 years development of the lower ribble valley northwest england displays evidence for a complex response to a sediment recharge event forced by land use change induced increases in erosion and sediment delivery the deposition of fluvial sediments during the late holocene was restricted to a series of reaches or depocenters separated by zones with no sediment accumulation constrained by older glacial and fluvial terrain apparent reach wide correlations of fluvial terraces break down under the scrutiny applied by comprehensive and extensive radiocarbon control bayesian testing of relative order models show that large scale geomorphological changes e g the progression from one terrace level to another were time transgressive between different depocenters the different histories of sediment delivery and storage are probably a function of local and process scale variations in these depocenters and reflect dis connectivity relationships within a reach in propagating a basin scale change superslug in the sediment regime disconnectivity in the depositional regime through a fluvial reach limits what we can reconstruct in terms of sediment budgets but radiocarbon dating of multiple palaeochannels offers considerable potential for landform based research to uncover rates of change within individual depocenters copyright 2009 john wiley sons ltd

analysis of a new geomorphological inventory of landslides in valles marineris mars abstract we completed a systematic mapping of landslides in a 10 5 km 2 area in tithonium and ius chasmata valles marineris mars where landslides are abundant using visual interpretation of medium to high resolution optical images we mapped and classified the geometry of 219 mass wasting features including rock slides complex compound failures rock avalanches debris flows and rock glacier like features for a total landslide area of a lt 4 4 10 4 km 2 44 of the study area a proportion larger than previously recognised studying the landslide inventory we showed that the probability density of landslide area p a l follows a power law with a scaling exponent 1 35 0 01 significantly different from the exponents found for terrestrial landslides 2 2 and 2 4 this indicates that the proportion of large landslides a l 10 7 m 2 is larger on mars than on earth we estimated the volume v l of a subset of 49 deep seated slides in our study area and found that the probability density of landslide volume p v l obeys a power law trend typical of terrestrial rock falls and rock slides with a slope 1 03 0 01 from the combined analysis of landslide area and volume measurements we obtained a power law dependency comparable to a similar relationship obtained for terrestrial bedrock landslides v l 1 2 0 8 a l 1 25 0 03 from the fall height h l and run out length l l of a subset of 83 slides unaffected by topographic confinement we obtained the mobility index heim s ratio h l l l a measure of the apparent friction angle of the failed materials 14 4 0 4 slope stability simulations and back analyses performed adopting a limit equilibrium method and using monte carlo approaches on failed and stable slopes suggest that the large landslides in valles marineris were seismically induced

mobility of large rock avalanches evidence from valles marineris mars measurements of h l height of drop length of runout vs volume for landslides in valles marineris on mars show a trend of decreasing h l with increasing volume this trend which is linear on a log log plot is parallel to but lies above the trend for terrestrial dry rock avalanches this result and estimates of 10 4 to 10 5 pa yield strength suggest that the landslides were not water saturated as suggested by previous workers the offset between the h l vs volume trends shows that a typical martian avalanche must be nearly two orders of magnitude more voluminous than a typical terrestrial avalanche in order to achieve the same mobility this offset might be explained by the effects of gravity on flows with high yield strengths these results should prove useful to future efforts to resolve the controversy over the mechan ics of long runout avalanches

2000 years of sediment borne heavy metal storage in the yorkshire ouse basin ne england uk floodplain overbank sediments are often used to evaluate the influence of environmental change on sediment and chemical fluxes within river basins this paper presents the results of an investigation of heavy metal storage in seven floodplain reaches in the yorkshire ouse basin in north east england floodplain heavy metal storage has been greatest since c 1750 and many of the post 1750 sedimentary units exhibit heavy metal values that exceed recommended trigger and guideline values for contaminated land relatively high heavy metal storage occurs from ad 1250 1750 in most of the reaches these patterns are related to 2000 years of pb and zn mining in the yorkshire dales and c 250 300 years of industrial and urbanization activity around leeds and bradford and increased delivery of fine grained sediment during the last millennium possibly owing to factors such as population growth and agricultural expansion during the middle ages and climate change during the little ice age copyright 1999 john wiley sons ltd

volcanism around k t boundary time its role in an impact scenario for k t extinction events abstract a widespread debate on the cretaceous tertiary k t boundary 65 1 ma extinctions has largely revolved around an impact or a volcanic cause evidence for both events is strengthened by recent work impact triggered deccan volcanism or independent impact and mantle plume events have been suggested this review examines evidence for both events and suggests that they overlapped in time but with globally uneven effects the combined effects produced generally inhospitable k t environments leading to mass extinctions although some life forms flourished afterwards volcanic contributions to the k t boundary environment probably include increased platinum group element pge and acid rain fall out particularly from large scale mantle upwellings e g deccan cameroon and coral sea events a previously proposed post k t greenland starting plume apparently already existed in the cretaceous k t features such as the iridium ir anomaly most likely include longer term volcanic as well as sudden meteoritic impact contributions volcanic contributions were greatest from southern hemisphere sources whereas meteorite impacts featured in the northern hemisphere

rock drumlins and megaflutes of the niagara escarpment ontario canada a hard bed landform assemblage cut by the saginaw huron ice stream abstract the late wisconsin c 18 000 ybp saginaw huron ice stream shis of the laurentide ice sheet was as much as 800 km long and 250 km wide in the great lakes basin of mid continent north america in its onset zone in the upper lake huron basin of ontario canada it flowed south from the high standing canadian shield to move over gently dipping ordovician and silurian dolostones devoid of glacial sediment cover the onset zone is recorded by a distinct hard bed landform assemblage across 3000 km2 of north facing escarpments niagara fossil hill and kagawong and dip slope pavements on the bruce peninsula and manitoulin island and the adjacent floor of lake huron a wide range of glacially streamlined rock landforms were carved into dolostones below fast flowing ice the largest are 30 km wide bullet shaped escarpment promontories that face upglacier superposed on these are swarms of rock drumlins up to 5 km wide with downglacier lengths of as much as 10 km promontories and drumlins record streaming of dirty basal ice around escarpment highs and create a distinct zig zag planform to the escarpments in turn down dip trailing edge dolostone pavements are corrugated by kilometre long megagrooves and megaflutes cut by basal ice flowing around resistant high standing bioherm mounds on dolostone bedding planes the geomorphology of the niagara escarpment does not primarily reflect a lengthy history of preglacial cenozoic fluvial erosion as classically argued but geologically brief episodes of accelerated abrasion and quarrying below ice streams within successive pleistocene ice sheets

mass movements on venus preliminary results from magellan cycle 1 observations mass movements on venus seen in radar images acquired by the magellan spacecraft during its first mapping cycle are easily interpreted within the scheme commonly used to classify terrestrial landslides rock slumps rock and or block slides rock avalanches debris avalanches and possibly debris flows are seen in areas of high relief and steep slope gradients and are most abundant in the tectonic troughs that crisscross much of the equatorial region of venus many classes of regolith and sediment movements are not seen such features might be too small to resolve in the 75 meter per picture element radar images or their absence may reflect the relatively thin cover of fine sediments inferred from emissivity measurements and other observations venusian landslides like those found within the valles marineris on mars tend to come from escarpments typically higher than those on earth they appear to fall between the terrestrial and martian height to length trends they are also somewhat larger using length as a surrogate for volume than terrestrial subaerial landslides but smaller than their martian counterparts good morphologic analogs can be found in terrestrial volcanic slides both subaerial and submarine oversteepening of volcanic edifices by intrusion and subsequent lateral collapse appears responsible for shaping a number of large isolated volcanos on venus faulting and seismically induced accelerations are probably responsible for the majority of non volcanic mass movements the atmosphere may participate in promoting the movement of some of the landslide debris but environmental factors e g rainfall temperature cycling do not appear to play as dominant a role as they do on earth based on the types and locations of landslides seen in the magellan data it is possible to scale the terrestrial occurrence rate to venus if venus is as seismically and volcanically active as the earth than of order one major landslide i e discernable in magellan images or 5 10 km in runout distance should occur per year which careful re examination of magellan images acquired during later mapping cycles may be able to detect