increased late pleistocene erosion rates during fluvial aggradation in the garhwal himalaya northern india the response of surface processes to climatic forcing is fundamental for understanding the impacts of climate change on landscape evolution in the himalaya most large rivers feature prominent fill terraces that record an imbalance between sediment supply and transport capacity presumably due to past fluctuations in monsoon precipitation and or effects of glaciation at high elevation here we present volume estimates chronological constraints and 10 be derived paleo erosion rates from a prominent valley fill in the yamuna catchment garhwal himalaya to elucidate the coupled response of rivers and hillslopes to pleistocene climate change although precise age control is complicated due to methodological problems the new data support formation of the valley fill during the late pleistocene and its incision during the holocene we interpret this timing to indicate that changes in discharge and river transport capacity were major controls compared to the present day late pleistocene hillslope erosion rates were higher by a factor of 2 4 but appear to have decreased during valley aggradation the higher late pleistocene erosion rates are largely unrelated to glacial erosion and could be explained by enhanced sediment production on steep hillslopes due to increased periglacial activity that declined as temperatures increased alternatively erosion rates that decrease during valley aggradation are also consistent with reduced landsliding from threshold hillslopes as a result of rising base levels in that case the similarity of paleo erosion rates near the end of the aggradation period with modern erosion rates might imply that channels and hillslopes are not yet fully coupled everywhere and that present day hillslope erosion rates may underrepresent long term incision rates

palaeo moisture evolution in monsoonal central asia during the last 50 000 years abstract the late quaternary climate history of monsoonal central asia was inferred from 75 palaeoclimatic records which provide information about moisture conditions in the last 50 ka or part of this period wet conditions occurred during middle and late marine isotope stage 3 while the last glacial maximum lgm was characterized by dry climate conditions in the region a stepwise climate amelioration is suggested by the climate records following the lgm several climate signals of this period which were reported from high latitude ice core records are preserved in archives from monsoonal central asia as well during the early holocene high effective moisture was inferred from most records from the area dominated by the indian monsoon e g the tibetan plateau suggesting that holocene optimal climate conditions occurred there during this period in contrast areas which are dominated by the south east asian monsoon se monsoon and the westerlies in north western and north central china mongolia do not uniformly show an early holocene climate optimum for this area optimal conditions prevailed during the mid holocene these apparent contradictions can possibly be explained by the regional uplift and descent of air masses in the holocene during the early holocene strengthened insolation possibly caused an enhanced low level convergence over the tibetan plateau which led to the intensification of the summer monsoon the strong air uplift caused intensified precipitation and air divergence in the upper troposphere over the tibetan plateau the areas adjacent to the north therefore experienced an intensified descent of air masses and consequently increased aridity the majority of the palaeoclimatic records suggest reduced effective moisture since the late holocene in the region

neotectonically triggered instability around the palaeolake regime in central kumaun himalaya india mass wasting often results from the combined effect of tectonic and climate processes it has not only resulted in human casualties on large scale but has also ruined agricultural land and disrupted hydro power projects and other governmental as well as private property despite the belief that prevention is inevitably better than cure decrease in future hazards requires proper dissemination of knowledge to the himalayan inhabitants considering this we investigated a part of kumaun himalaya to understand the cause of cloud burst induced mass movements along the saryu river that took place on 18th august 2010 and subsequently on 12 14th september 2012 a number of quaternary faults e g dulam fault df dulam gadhera fault dgf and vongarh gason fault vgf in the zone of a major thrust berinag thrust in the studied sector are invariably active as evident by various geomorphic features e g saw cutting of host rocks immature topography deflecting river courses ponding of ancient drainage development of cascades formation of unpaired fluvial terraces and series of triangular fault facets the fragile lithology deep v shaped valleys accelerating erosion and incision with higher uplift due to tectonic upheaval along the active faults are also responsible for rainfall induced catastrophes in the region additionally morphometric analysis reveals that the saryu basin is elongated and tilted further the tectonic tilting and moderate to coarse drainage density may possibly be responsible for quicker runoff amplified erosion and subsequently increased flooding around the study area we infer that the area is not only controlled by topography but may also have been affected by the hydraulic factors such as climate in addition the drainage is dominated mostly by first order streams which seem to be indicative of higher chances of flooding as most of the water is concentrated in a single channel during monsoon season we believe that the similar studies done in the other sectors will be helpful in reducing not only the huge loss of life but may also help in protecting ongoing and huge hydropower and other developmental projects in this newly born state

insolation values for the climate of the last 10 million years new values for the astronomical parameters of the earth s orbit and rotation eccentricity obliquity and precession are proposed for paleoclimatic research related to the late miocene the pliocene and the quaternary they have been obtained from a numerical solution of the lagrangian system of the planetary point masses and from an analytical solution of the poisson equations of the earth moon system the analytical expansion allows the direct determination of the main frequencies with their phase and amplitude numerical and analytical comparisons with the former astronomical solution ber78 are performed so that the accuracy and the interval of time over which the new solution is valid can be estimated the corresponding insolation values have also been computed this analysis leads to the conclusion that the new values are expected to be reliable over the last 5 ma in the time domain and at least over the last 10 ma in the frequency domain

abnormal monsoon years and their control on erosion and sediment flux in the high arid northwest himalaya abstract the interplay between topography and indian summer monsoon circulation profoundly controls precipitation distribution sediment transport and river discharge along the southern himalayan mountain front shf the higher himalayas form a major orographic barrier that separates humid sectors to the south and arid regions to the north during the indian summer monsoon vortices transport moisture from the bay of bengal swirl along the shf to the northwest and cause heavy rainfall when colliding with the mountain front in the eastern and central parts of the himalaya precipitation measurements derived from passive microwave analysis ssm i show a strong gradient with high values at medium elevations and extensive penetration of moisture along major river valleys into the orogen the end of the monsoonal conveyer belt is near the sutlej valley in the nw himalaya where precipitation is lower and rainfall maxima move to lower elevations this region thus comprises a climatic transition zone that is very sensitive to changes in indian summer monsoon strength to constrain magnitude temporal and spatial distribution of precipitation we analyzed high resolution passive microwave data from the last decade and identified an abnormal monsoon year amy in 2002 during the 2002 amy violent rainstorms conquered orographic barriers and penetrated far into otherwise arid regions in the northwest himalaya at elevations in excess of 3 km asl while precipitation in these regions was significantly increased and triggered extensive erosional processes i e debris flows on sparsely vegetated steep hillslopes mean rainfall along the low to medium elevations was not significantly greater in magnitude this shift may thus play an important role in the overall sediment flux toward the himalayan foreland using extended precipitation and sediment flux records for the last century we show that these events have a decadal recurrence interval during the present day monsoon circulation hence episodically occurring amys control geomorphic processes primarily in the high elevation arid sectors of the orogen while annual recurring monsoonal rainfall distribution dominates erosion in the low to medium elevation parts along the shf

monsoon variability and chemical weathering during the late pleistocene in the goriganga basin higher central himalaya india stable isotope analysis along with radiocarbon and luminescence dating of late pleistocene lacustrine deposits at burfu in the higher central himalaya are used to interpret hydrologic changes in the lake basin from 15 5 ka to 14 5 ka the burfu lake was largely fed by melting glaciers a warming event at 14 5 ka suggests an enhanced monsoon and increased carbonate weathering from 13 5 ka to 12 5 ka the isotopic data suggest large amplitude climate variability following this the isotope data suggest a short lived abrupt cooling event comprising a 300 yr intense cool period followed by a 500 yr interval of moderate climate a shift in isotope values at 11 3 ka may signify a strengthening monsoon in this region the inferred climatic excursions appear to be correlative at least qualitatively with global climatic events and perhaps the burfu lake sequence provides regional evidence of globally recorded excursions this study also suggests a potential use of radiocarbon ages in specific environments as a paleoenvironmental proxy

persistent solar influence on north atlantic climate during the holocene surface winds and surface ocean hydrography in the subpolar north atlantic appear to have been influenced by variations in solar output through the entire holocene the evidence comes from a close correlation between inferred changes in production rates of the cosmogenic nuclides carbon 14 and beryllium 10 and centennial to millennial time scale changes in proxies of drift ice measured in deep sea sediment cores a solar forcing mechanism therefore may underlie at least the holocene segment of the north atlantic9s 1500 year cycle the surface hydrographic changes may have affected production of north atlantic deep water potentially providing an additional mechanism for amplifying the solar signals and transmitting them globally

late cenozoic uplift of mountain ranges and global climate change chicken or egg the high altitudes of most mountain ranges have commonly been ascribed to late cenozoic uplift without reference to when crustal thickening and other tectonic processes occurred deep incision and recent denudation of these mountain ranges abundant late cenozoic coarse sediment near them and palaeobotanical evidence for warmer climates where high mountain climates today are relatively cold have traditionally been interpreted as evidence for recent uplift an alternative cause of these phenomena is late cenozoic global climate change towards lower temperatures increased alpine glaciation a stormier climate and perturbations to humidity vegetative cover and precipitation

the emplacement of the active lava flow at sinabung volcano sumatra indonesia documented by structure from motion photogrammetry abstract an effusive eruption at sinabung volcano in indonesia began in december 2013 we use structure from motion sfm photogrammetric techniques to create digital elevation models dems of the active lava flow we build dems from photographs taken during two separate time periods and from two separate low cost handheld cameras and compare them with a pre eruption dem to assess the quality and accuracy of photogrammetric dems created using different cameras calculate flow volume and long term average effusion rate and document changes in flow morphology on september 22nd 2014 the lava flow was 2 9 km long and had a volume of 1 03 0 14 108 m3 leading to an estimated time averaged discharge rate of 4 8 0 6 m3 s 1 differencing the photogrammetric dems shows that during the two week field campaign topographic changes of the flow occurred in zones along the flow front and on the upper flank a finding supported by relatively high temperatures in corresponding thermal images the deformation can be explained by active advance at the flow front and development of instabilities and collapse on the upper flanks large pyroclastic density currents associated with gravitational collapse of upper flank instabilities in october 2014 and june 2015 were caused by lava growing over ridges that had initially confined the flow to a pre existing channel this work demonstrates the ability of sfm photogrammetry to measure or identify the lava flow volume time averaged discharge rate flow emplacement rate and style as well as the development of gravitational instabilities our results show the potential of sfm photogrammetry as a cost and time effective method of repeatedly measuring active volcanic features and monitoring hazards at sinabung and during similar eruptions

chronology and rates of faulting of ventura river terraces california new evidence concerning the chronology of four late pleistocene terraces of the ventura river near oak view california that are vertically offset and tilted by reverse and reverse flexural slip faults provides a means of estimating rates of fault movement and downcutting by the ventura river radiocarbon ages of charcoal contained within terrace deposits date two of the terraces correlation of soils that have developed on terrace deposits and extrapolation of the rate of vertical displacement of the arroyo parida santa ana fault not a flexural slip fault date the others resulting age estimates for the four main late pleistocene terraces are qt5b 30 000 qt6a 38 000 qt6b 54 000 and qt6c 92 000 yr b p vertical slip rates on flexural slip faults range from 0 3 to 1 1 mm yr and apparently are related to the rate form and mechanics of folding of the north limb of the ayers creek canada larga syncline average rates of downcutting of the ventura river for several intervals during the late pleistocene estimated from the chronology and relative elevation of river terraces north of the arroyo panda santa ana fault upstream from the zone of faulting vary from 0 5 to 1 3 mm yr the range in rates probably reflects variations in local uplift as well as adjustments to changing eustatic sea level climatic conditions and or regional deformation of the western transverse ranges the average rate of downcutting of the ventura river north of the zone of flexural slip faulting is 0 8 mm yr compared with 1 2 to 2 2 mm yr in the deformation zone immediately to the south this apparently indicates that during tectonic deformation there is an approximate balance between the rate of uplift due to faulting and folding and the rate of downcutting by the fluvial system

river profiles along the himalayan arc as indicators of active tectonics abstract longitudinal profiles along sixteen major transverse himalayan rivers add important constraints to models of active continental subduction and its evolution these profiles are characterized by a zone of relatively high gradient that cannot be associated with differential resistence to erosion in all cases the base of the zone of increased gradients correlates with 1 the topographic front between the lesser and high himalayas 2 the narrow belt of intermediate magnitude thrust earthquakes 3 the main central thrust zone mct these features define a small circle in the central portion of the himalayan arc these correlations suggest that the discontinuity in the river profiles and the other features are controlled by a major tectonic boundary between the rising high himalayas and the lesser himalayas no sharp increases in gradient are observed near the main boundary thrust mbt except on a few rivers such as the jhelum or kundar where the mbt lies close to both the mct and the seismic belt thus it is unlikely that the mbt is a major tectonic boundary the diversion of river courses along the mbt and around anticlines in the sub himalayas has probably been caused by aggradation near the rosion deposition boundary upstream of uplifts in the mahabharat range and sub himalayas a parallel is drawn between the himalayas and new guinea based on the hypothesis that continent arc collision of the type occurring in northern australia preceded continent continent collision in the himalayas the present sedimentary tectonic phase in new guinea resembles the subathu paleocene eocene phase in the himalayas incipient counterparts of the major himalayan structures including the mct and the mbt are recognized in new guinea the drainage patterns in the himalayas and in new guinea bear a similar relation to major structures this suggests that 1 the tectonic evolution of the himalayas has been rather uniform since early stages of collision and 2 the himalayan drainage was also formed at these early stages and is therefore antecedent to the rise of the high himalayas

palaeoclimatic significance of magnetic properties from late quaternary lacustrine sediments at pithoragarh kumaun lesser himalaya india abstract mineral magnetic studies were carried out on lacustrine deposits from pithoragarh palaeolake kumaun lesser himalaya india these deposits have already provided valuable information for the reconstruction of palaeoclimatic changes and tectonic uplift in the himalayan region according to radiocarbon chronology the lake existed from 35 to 10 kyr bp using magnetic data radiocarbon ages and lithology the top of the well studied 13 m thick wadda section can be correlated to the basal part of the 4 7 m thick riyasi section fuzzy c means cluster analysis using only magnetic parameters enables a subdivision of the riyasi section into five magnetic zones based on three clusters these clusters are related to the relative contribution of the various magnetic constituents i e coarse hem c and ultrafine hem f grained hematite both showing relatively soft magnetic behaviour for the lowermost three zones existing pollen data from the wadda section helps to establish the climatic implications of the magnetic clusters and zones the model is as follows during humid periods magnetic mineralogy is mainly controlled by hem f formed in situ whereas during colder and more arid conditions detrital input of hem c and also hem f from the catchment area predominates climatic interpretation for the upper part of the section is attempted on the basis of the magnetic data but has to be confirmed by further pollen studies

fashion and phases of late pleistocene aggradation and incision in the alaknanda river valley western himalaya india abstract we study the aggradation and incision of the alaknanda river valley during the late pleistocene and holocene the morphostratigraphy in the river valley at deoprayag shows the active riverbed a cut terrace and a fill terrace the sedimentary fabric of the fill terrace comprises four lithofacies representing 1 riverbed accretion 2 locally derived debris fan 3 the deposits of waning floods and 4 palaeoflood records the sedimentation style coupled with geochemical analysis and optically stimulated luminescence osl dating indicate that this terrace formed in a drier climate and the river valley aggraded in two phases during 21 18 ka and 13 9 ka during these periods sediment supply was relatively higher incision began after 10 ka in response to a strengthened monsoon and aided by increase of the tectonic gradient the cut terrace formed at 5 ka during a phase of stable climate and tectonic quiescence the palaeoflood records suggest wetter climate 200 300 yr ago when the floods originated in the upper catchment of the higher himalaya and in the relatively drier climate 1 2 ka when locally derived sediments from the lesser himalaya dominated flood deposits maximum and minimum limits of bedrock incision rate at deoprayag are 2 3 mm a and 1 4 mm a

precipitation variability in the indian central himalaya during last ca 4 000 years inferred from a speleothem record impact of indian summer monsoon ism and westerlies abstract we report the first high resolution stalagmite record from indian central himalaya by using a combined oxygen and carbon isotopic study spanning the last 4000 years in addition to the multi decadal events the stalagmite data also provide information on the variability in the intensity of precipitation indian summer monsoon ism and westerlies in north indian hills during the late holocene the 18o values show strong variability between 2 1 and 8 9 the extremely high variability points to the monsoon from two different sources compared to other similar aged caves which are primarily controlled by one monsoon such as the east asian summer monsoon easm although ism has penetrated into some parts in the areas of easm in the past or the westerlies therefore we suggest that the westerlies played an important role in the late holocene climate of the indian himalaya as the source of the westerlies is mediterranean atlantic the north atlantic oscillation nao which was responsible for comparatively stronger westerlies in southern europe may have brought higher precipitation to the north indian hills the stronger westerlies may also have resulted in the highest precipitation between 0 5 and 0 25 ka bp 1450 1700 ad a part of the lia in contrast to the weakening of the indian summer monsoon ism in peninsular india the stalagmite has also recorded the driest period peaking at 3 2 ka bp which may be nearly synchronous with the final collapse of the harappan culture in northwest india

widespread aggradation in the mountainous catchment of the alaknanda ganga river system timescales and implications to hinterland foreland relationships abstract cut and fill type fluvial terraces are ubiquitous in the lesser himalayan zone of the alaknanda ganga ganges rivers system which flows perpendicular to himalayan lithotectonic units and traverses a steep climatic gradient lithofacies analysis of the sedimentary sequences of cut and fill terraces indicated that the valley aggradation took place via 1 channel bar development and excess sediment supply 2 debris flows composed of mixed rounded to sub rounded lithoclasts resulting from episodic high intensity rainfalls in the upper catchment or 3 debris flows or rockfalls generated by local landslides the luminescence chronology indicates that valley aggradation took place in two phases 49 25 ka and 18 11 ka the incision of the fill started soon after 11 ka paleoclimatic records from marine sediments indicate that the aggradation and incision in the alaknanda ganga river has oscillated in phase with global climatic variations glaciation deglaciation processes in the upper catchment produced huge amounts of sediment between 63 and 11 ka which was fluvially transferred to the lower valley via several cycles of erosion and deposition leading to extensive aggradation the climatic amelioration at 11 ka and the completion of deglaciation processes led to increased fluvial discharge and decreased sediment supply conditions conducive for incision of the alluvial fills records from the indo gangetic plain and the ganga delta demonstrate that the phase of aggradation was regional but that incision in the foreland started at least 2 3 ka later after 7 ka bedrock incision rates as calculated from dated alluvial covers of terraces that are separated by bedrock steps are spatially variable and fall within the range of rates reported from across the himalaya these estimated rates however are higher than the basin average erosion rates calculated using isotopic mass balance in riverbed sediments this study suggests that during the last 50 ka river dynamics in the himalayas were dominated by monsoon variability and the role of tectonic activity was limited to bedrock incision in few reaches only

aftershocks of the march 1999 chamoli earthquake and seismotectonic structure of the garhwal himalaya the aftershocks of the chamoli earthquake m b 6 3 of 28 march 1999 are analyzed to understand the seismotectonic structure of the garhwal himalaya the permanent as well as temporary microearthquake network data are used the mainshock occurred on the basement thrust by thrust faulting the aftershocks on the other hand are triggered at the seismogenic faults to the south of the main central thrust mct by thrust faulting as well as by strike slip faulting and all the events occurred above the plane of detachment basement thrust the mct is not the seismogenic fault

bedrock incision rock uplift and threshold hillslopes in the northwestern himalayas the topography of tectonically active mountain ranges reflects a poorly understood competition between bedrock uplift and erosion dating of abandoned river cut surfaces in the northwestern himalayas reveals that the indus river incises through the bedrock at extremely high rates 2 12 mm yr 1 in the surrounding mountains the average angles of hillslopes are steep and essentially independent of erosion rate suggesting control by a common threshold process in this rapidly deforming region an equilibrium is maintained between bedrock uplift and river incision with landsliding allowing hillslopes to adjust efficiently to rapid river down cutting

reconstruction of late quaternary climate and seismicity using fluvial landforms in pindar river valley central himalaya uttarakhand india abstract fluvial landforms in the pindar river valley are investigated to understand the role of temporal variability in the indian summer monsoon ism and the spatial changes in crustal deformation employing the conventional geomorphological and sedimentological concepts supported by optical dating three major phases of valley fill aggradation separated by phases on non deposition are discerned an oldest aggradation phase is dated to 33 5 ka during relatively strengthened ism corresponding to the later part of pluvial marine isotopic stage 3 mis 3 following this alluvial fan sedimentation impersistently continued during the declining phase of the ism until around 21 ka a second major aggradation phase 17 5 ka 13 ka occurred during the post lgm lateglacial strengthening of the ism in which contribution from tributary valleys overwhelmed the valley fill sedimentation a youngest aggradation phase dated to the middle to late holocene 8 ka 3 6 ka represents the transitional climate during which sporadic high sediment fluxes both from the upper catchment and tributary streams led to the development of fossil valleys abandonment of old channels the spatial variability in the incision uplift rate based on river strath terraces reveals that the terrain is undergoing differential crustal deformation two zones of relatively high crustal deformation are identified these are located in the vicinity of the main central thrust mct and is attributed to the activity along the transverse fault and the in the inner lesser himalaya for which the thrust propagated fold associated with regional north south compression is implicated the study suggests that fluvial landforms valley fill and strath terraces in the pinder river valley are genetically related to the multi millennial scale changes in the ism and spatial and temporal changes in the crustal deformation associated with regional compression

reconstruction of last glacial to early holocene monsoon variability from relict lake sediments of the higher central himalaya uttrakhand india abstract proglacial lake sediments at goting in the higher central himalaya were analyzed to reconstruct the summer monsoon variability during the last glacial to early holocene sedimentary structures high resolution mineral magnetic and geochemical data suggest that the lacustrine environment experienced fluctuating monsoonal conditions optically stimulated luminescence osl dating indicates that the lake sedimentation occurred before 25 ka and continued after 13 ka during this period goting basin witnessed moderate to strengthened monsoon conditions around 25 ka 23 5 ka 22 5 ka 22 ka 18 ka 17 ka 16 5 ka and after14 5 13 ka the last glacial phase ended with the deposition of outwash gravel dated at 11 ka indicating glacial retreat and the onset of holocene condition additionally centennial scale fluctuations between 16 5 ka and 12 7 ka in the magnetic and geochemical data are seen a close correspondence at the millennial scale between our data and that of continental and marine records from the indian sub continent suggests that goting basin responded to periods of strengthened monsoon during the last glacial to early holocene we attribute the millennial scale monsoon variability to climatic instability in higher northern latitudes however centennial scale abrupt changes are attributed to the result of albedo changes on the himalaya and tibetan plateau

palaeoclimatic response to quaternary gravels a case study from kumaun himalaya india study of quaternary intramontane bhimtal palaeolake deposits and the gaula piedmont fan deposits representing sediment source to sink scenario respectively have revealed that gravelly sequences have directly responded to climatic turnovers creating contrasting lithofacies associations humid climatic conditions favoured thickly developed river generated clast supported gravelly deposits composed of clasts derived from a distant source these deposits show intense lateral and vertical changes in lithofacies constitution in contrast arid phases are represented by extensive debris flows composed of clasts derived from adjacent mountain slopes gravelly deposits systematically interbedded in the stratigraphic records have potential for palaeoclimatic studies that is sometimes ignored

continental record of the southwest monsoon during the last 130 ka evidence from the southern margin of the thar desert india abstract field stratigraphy sedimentology and luminescence dating of the exposed fluvial and aeolian sequences from the southern desert margin were used to discern the pattern of southwest monsoon variability during the last 130 ka the sedimentary architecture and textural attributes of the sediments belonging to the period 130 120 ka suggests the existence of a meandering river system consequent to enhanced southwest monsoon conditions a shift from a meandering to a braided pattern during 120 100 ka indicates a phase of reduced precipitation presence of flood plain fines and bedded calcretes during 100 70 ka suggest a period of enhanced monsoon with seasonality following this a phase of weak monsoon activity was observed during 70 60 ka regional flood plain aggradation and pedogenesis during the period termination of a regional fluvial phase around 30 ka and incision of dunes dated to 20 11 ka suggest that the present rivers occupied their course between 11 ka drowned valleys in the estuarine zones suggest that the incision began during the low sea stand around 20 ka when the rivers were graded to the exposed shelf the incision intensified with the re establishment of monsoon during the early holocene

formal subdivision of the holocene series epoch a discussion paper by a working group of intimate integration of ice core marine and terrestrial records and the subcommission on quaternary stratigraphy international commission on stratigraphy this discussion paper by a working group of intimate integration of ice core marine and terrestrial records and the subcommision on quaternary stratigraphy sqs of the international commission on stratigraphy ics considers the prospects for a formal subdivision of the holocene series epoch although previous attempts to subdivide the holocene have proved inconclusive recent developments in quaternary stratigraphy notably the definition of the pleistocene holocene boundary and the emergence of formal subdivisions of the pleistocene series epoch mean that it may be timely to revisit this matter the quaternary literature reveals a widespread but variable informal usage of a tripartite division of the holocene early middle or mid and late and we argue that this de facto subdivision should now be formalized to ensure consistency in stratigraphic terminology we propose an early middle holocene boundary at 8200 a bp and a middle late holocene boundary at 4200 a bp each of which is linked to a global stratotype section and point gssp should the proposal find a broad measure of support from the quaternary community a submission will be made to the international union of geological sciences iugs via the sqs and the ics for formal ratification of this subdivision of the holocene series epoch copyright 2012 john wiley sons ltd

late quaternary climatic changes in the eastern kumaun himalaya india as deduced from multi proxy studies abstract an event of neotectonic activity on an ne sw trending subsidiary fault in the zone of e w running intracrustal boundary thrust south almora thrust in the champawat district of eastern kumaun himalaya resulted in creation of a lake at ca 21 5 bp the lake drained in the late holocene leaving behind a 5 0 m thick sedimentary sequence of mostly black and carbonaceous mud with a minor magnetic reversal between 20 5 and 19 7 ka bp at the base the profile studied by using multi proxies e g carbon isotopes pollen analysis palaeo and mineral magnetism and clay minerals has recorded globally well established abrupt climatic events in the last 20 000 years such as the lgm older dryas od younger dryas yd holocene warming 8 2 ka and 4 2 ka events most events estimated assuming a constant rate of sediment accumulation for similar lithologies may be related to the rapid changes in the local climate and albedo structure the itcz may have played a key role in controlling the behavior of the southwest monsoon from the lgm

climatic fluctuations during the lia and post lia in the kumaun lesser himalaya india evidence from a 400 y old stalagmite record this paper presents the first stable isotope delta o 18 and delta c 13 data of a similar to 400 years 1590 2006 ad long annual to decadal resolution speleothem record collected from the indian lesser himalaya the data show a variation from 2 7 to 5 9 parts per thousand in delta o 18 and 5 3 to 8 8 parts per thousand in delta c 13 the isotopic analyses indicate that the climate during this period can be divided into two stages a wet phase during the little ice age lia 1590 1850 ad and comparatively dry phase during the post lia after 1850 ad however the record also documents the minor dry events during the lia and a wet episode after the lia within the age uncertainty the dry spells during the lia are linked with the historical drought events in the indian subcontinent and similar latitudes the isotopic record is consistent with a number of previous studies in the areas influenced by the westerlies but appears to be conflicting to the regions dominated by the indian summer monsoon ism this may be due to the possible changes in the strength of westerlies in the study area and added by negative anomaly of north atlantic oscillation nao during the lia c 2012 elsevier ltd and inqua all rights reserved

late quaternary chronology of major dune ridge development in the northeast rub al khali united arab emirates the northeastern sector of the rub al khali desert in the eastern united arab emirates uae is dominated by large ne sw trending dune ridges orientated perpendicular to the currently prevailing northwesterly wind regime in this study extensive use has been made of artificially exposed sections through these major dune ridges that reveal internal sedimentary structures and allow an intensive high resolution sampling programme to be carried out here we present the optical dating results for samples from 7 sections the results indicate that dune activity and preservation occurred within the periods 7 3 ka 16 10 ka and 22 20 ka with evidence of earlier preservation during marine oxygen isotope stages mis 3 and 5 with net accumulation rates in the range 2 2 25 m ka 1 in several instances hiatuses in the preserved record of dune accumulation coincide with stratigraphic bounding surfaces visible in the exposed section profiles with associated truncation of internal sedimentary structures caution must be exercised when interpreting such gaps in the recorded accumulation chronologies of these dunes since these may simply constitute phases of low preservation potential rather than phases of low aeolian activity other factors such as sediment supply and availability in relation to sea level dynamics may be significant and are also considered

fluvial incision and tectonic uplift across the himalayas of central nepal the pattern of fluvial incision across the himalayas of central nepal is estimated from the distribution of holocene and pleistocene terraces and from the geometry of modern channels along major rivers draining across the range the terraces provide good constraints on incision rates across the himalayan frontal folds sub himalaya or siwaliks hills where rivers are forced to cut down into rising anticlines and have abandoned numerous strath terraces farther north and upstream in the lesser himalaya prominent fill terraces were deposited probably during the late pleistocene and were subsequently incised the amount of bedrock incision beneath the fill deposits is generally small suggesting a slow rate of fluvial incision in the lesser himalaya the terrace record is lost in the high range where the rivers are cutting steep gorges to complement the terrace study fluvial incision was also estimated from the modern channel geometries using an estimate of the shear stress exerted by the flowing water at the bottom of the channel as a proxy for river incision rate this approach allows quantification of the effect of variations in channel slope width and discharge on the incision rate of a river the determination of incision rates requires an additional lithological calibration the two approaches are shown to yield consistent results when applied to the same reach or if incision profiles along nearby parallel reaches are compared in the sub himalaya river incision is rapid with values up to 10 15 mm yr it does not exceed a few millimeters per year in the lesser himalaya and rises abruptly at the front of the high range to reach values of 4 8 mm yr within a 50 km wide zone that coincides with the position of the highest himalayan peaks sediment yield derived from the measurement of suspended load in himalayan rivers suggests that fluvial incision drives hillslope denudation of the landscape at the scale of the whole range the observed pattern of erosion is found to closely mimic uplift as predicted by a mechanical model taking into account erosion and slip along the flat ramp flat geometry of the main himalayan thrust fault the morphology of the range reflects a dynamic equilibrium between present day tectonics and surface processes the sharp relief together with the high uplift rates in the higher himalaya reflects thrusting over the midcrustal ramp rather than the isostatic response to reincision of the tibetan plateau driven by late cenozoic climate change or late miocene reactivation of the main central thrust

holocene forcing of the indian monsoon recorded in a stalagmite from southern oman a high resolution oxygen isotope record from a thorium uranium dated stalagmite from southern oman reflects variations in the amount of monsoon precipitation for the periods from 10 3 to 2 7 and 1 4 to 0 4 thousand years before the present ky b p between 10 3 and 8 ky b p decadal to centennial variations in monsoon precipitation are in phase with temperature fluctuations recorded in greenland ice cores indicating that early holocene monsoon intensity is largely controlled by glacial boundary conditions after approximately 8 ky b p monsoon precipitation decreases gradually in response to changing northern hemisphere summer solar insolation with decadal to multidecadal variations in monsoon precipitation being linked to solar activity

late pleistocene holocene climate and sea level changes inferred based on the tidal terrace sequence kachchh western india abstract an estuarine tidal terrace sequence at the mouth of the kharod river kachchh western india is investigated for pleistocene to holocene climate and sea level changes based on sedimentology major element geochemistry mineralogy supported by optical dating the study reports a lowered sea level during 13 8 ka followed by gradual rise in the sea level until around 6 ka this is ascribed to a combination of enhanced melt water discharge and strengthened indian summer monsoon ism the temporal changes in major elements detrital proxies suggest a fluctuating to an overall arid monsoon conditions during 5 7 to 3 1 ka with a rapidly rising sea level this is further supported by the dominance of fine textured sediment along with the occurrences of shell rich horizon in the absence of any evidence of land level changes the study suggests that at around 6 ka to 3 ka the sea was approximately 2 m higher then present the decline in the concentration of geochemical proxies and occurrence of aeolian sand after 3 ka is interpreted as the onset of aridity and present day like conditions the three levels of sea stands during early middle and late holocene are synchronous with various archeological harappan settlements in the region

formation of paleovalleys in the central himalaya during valley aggradation abstract the formation of paleovalleys in mountainous regions is considered to result from extreme events such as landslides and glacial or landslide lake outburst floods according to ipcc 2012 the extreme events are rarest of the rare weather climatic events when the climate weather variable is significantly above or below the defined threshold value the present study suggests that paleovalleys can also form during years long periods of valley aggradation a series of paleovalleys thus formed runs parallel to the present river course in this study we suggest that paleovalleys in the alaknanda valley of the central himalaya have formed in two ways 1 major valley aggradation and 2 local events of landsliding and lake breaching most of the paleovalleys in the alaknanda valley formed during a major valley aggradation phase between 15 and 8 ka paleovalleys formed due to local landsliding also formed around 8 ka local landslides were triggered due to high rainfall in lower valley reaches during unstable climatic conditions therefore the formation of paleovalleys both by regional and local mode within 15 8 ka indicates that the valley was receiving excess sediment from upper catchment as well as from lower reaches during this period this phase of excess sediment supply and valley aggradation coincides well with post glacial climatic amelioration therefore the study underlines the role of climate in the time scales of 10 3 years in shaping the landscape of an active mountain like the himalaya the role of other landscape changing agencies such as tectonics and erosion is not accounted in the present study

disequilibrium of holocene sediment yield in glaciated british columbia it is generally supposed that specific sediment yield the quantity of sediment passing a monitored river cross section per unit area drained upstream of that section declines as the area drained increases1 3 part of the sediment mobilized from the land surface is supposed to go back into storage at field edges and on footslopes and floodplains in contrast we show here that data from british columbian rivers reveal a pattern of increasing specific sediment yield at all spatial scales up to 3 104 km2 this results from the dominance of secondary remobilization of quaternary sediments along river valleys over primary denudation of the land surface the result controverts the conventional model which has been derived from studies of small highly disturbed agricultural catch ments the rivers are still responding to the last glaciation giving a landscape relaxation time greater than 10 kyr this holds pro found implications for geomorphological theory and for studies of erosion