early eocene leptictida pantolesta creodonta carnivora and mesonychidae mammalia from the eureka sound group ellesmere island nunavut we describe the leptictid prodiacodon the pantolestids palaeosinopa sp nov cf palaeosinopa and pantolestidae gen et sp indet the creodonts palaeonictis and prolimnocyon the carnivorans viverravus cf vulpavus and miacis and the mesonychid pachyaena from early eocene i e wasatchian strata of the eureka sound group on central ellesmere island nunavut palaeosinopa and palaeonictis may have originated in mid latitude north america and subsequently migrated to europe via a north atlantic land bridge while prolimnocyon and pachyaena probably originated in asia additionally the occurrence of pachyaena in the early eocene of europe probably is best explained by dispersal from high latitude north america to europe via a north atlantic land bridge we update the eureka sound group mammalian faunal list

stratigraphy composition and form of the deccan basalts western ghats india in the western ghats between latitudes 18 20 n and 19 15 n 7000 km2 of deccan basalt have been mapped with the primary objective of establishing a flow stratigraphy as a guide to the volcanic history of the flood basalts using over 70 measured vertical sections major and trace element analyses of nearly 1200 samples and rare earth and87sr 86sr determinations for over 60 samples we divide the basalt into three subgroups and ten formations in this paper we describe the seven principal formations in the area and the most prominent individual flows

sr and 87sr 86sr in rivers draining the deccan traps india implications to weathering sr fluxes and the marine 87sr 86sr record around k t the concentration of dissolved sr and its 87sr 86sr has been measured in the headwaters of the krishna river system and west flowing western ghat rivers all of which have their drainage almost entirely in the deccan traps the sr concentration follows that of ca and mg with sr ca and sr mg ratios similar to that of deccan basalts suggesting that all these alkaline earths are released to waters nearly congruently from the deccan basalts during chemical weathering the 87sr 86sr range from 0 70614 to 0 70986 within that reported for the deccan basalts the dissolved sr flux from the deccan calculated from the measured data is 1 35 108 moles yr 1 0 4 of the global riverine flux which is nearly the same as the proportion of area covered by deccan basalts relative to the global drainage the flux however is a factor of 3 lower than that reported for the narmada tapti wainganga ntw rivers draining the northern deccan this difference in sr flux among rivers draining the various regions of deccan could be natural spatial temporal variations and or due to supply of sr to ntw rivers from nonbasaltic sources model calculations on the role of emplacement and weathering of deccan on marine sr isotope evolution around ktb and late tertiary show that deccan basalts can be an important contributor to the decline in 87sr 86sr during these periods it is shown that to account for the pre ktb dip in 87sr 86sr the flux requirement from deccan at that time would have to be several times the contemporary flux with 87sr 86sr of 0 705 0 708 considering that the area of deccan at ktb was about thrice the present area and that the weathering rate of deccan basalts may have been much higher in early stages following eruption such high fluxes at about ktb seem feasible the disproportionately higher flux requirement for sr is similar to that invoked to explain the pre ktb decrease in 187os 188os the calculations also show that the supply of unradiogenic sr from basalts can have significant control on the long term 66 to 55 ma decline of marine 87sr 86sr

formation of lava tubes and extensive flow field during the 1991 1993 eruption of mount etna detailed mapping during the 1991 1993 eruption of mount etna has shown that there is a relationship between tumuli ephemeral vents lava tubes and their parent lava flows during this eruption many tubes formed in stationary inflated a a lava flows ephemeral vents at the fronts of these stationary flows and above lava tubes fed secondary lava flows many of which subsequently developed new tubes the resulting complex network of tubes ephemeral vents and secondary flows was responsible for most of the widening thickening and lengthening of the 1991 1993 etna lava flow field the supply of relatively uncooled lava via tubes to distal parts of this flow field allowed lava to flow 3 km farther from the vent than the longest channel fed lava flow our observations suggest that lava tubes play a more important role in the formation of extensive a a flow fields on etna than has previously been recognized

a branched magma feeder system during the 1669 eruption of mt etna evidence from a time integrated study of zoned olivine phenocryst populations the 1669 eruption of mt etna was one of the most voluminous and devastating of its flank eruptions in historical times despite a large body of relevant research knowledge of the timing and duration of magma transfer and magma recharge through the internal plumbing system preceding and during the eruption is still limited to address that lack of knowledge we apply a three way integrated method linking systems analysis of crystals a time integrated study of zoned olivine populations and a forward modelling approach using thermodynamic calculations analysis of 202 olivine crystals erupted during the initial pre march 20 i e set1 and the final post march 20 i e set2 and mtrs stages of the eruption reveals the existence of three magmatic environments mes in which the majority of the olivine cores m 1 fo 75 78 and rims i e m 5 fo 51 59 and m 3 fo 65 69 formed application of the rhyolite melts software allowed us to constrain the key intensive variables associated with these mes we find that temperature water content and oxidation state vary between these mes application of diffusion modelling to the zoned olivine crystals allowed us to reconstruct the timing and chronology of melt and crystal transfer prior to and during the 1669 flank eruption we find that following the formation of the olivine cores m 1 fo 75 78 the reservoir m 1 was intruded by batches of more evolved degassed and possibly aphyric m 5 type magma commencing 1 center dot 5 years prior to eruptive activity this is the origin of the set1 olivine rims i e fo 51 59 in the months prior to eruption timescale data show that recharge activity along the newly established pathway m 1 m 5 increased notably starting in november 1668 only a few weeks after the first intrusive episode into the m 1 reservoir a second pulse of magma injections m 3 type magma occurred and a new pathway m 1 m 3 opened this is how the set2 olivine rims i e fo 65 69 formed for several weeks a bifurcated transport system with two dominant magma pathways developed along m 1 m 5 and m 1 m 3 dyke injections accompanied by vigorous seismicity in the days immediately before eruption the local magma transfer dynamics changed and the m 1 m 5 recharge activity slowed down as shown by a relative lack of crystals recording shorter timescales m 1 m 3 recharge however remained high and persisted following the eruption onset on march 11 during which the set1 lavas were drained we propose that the change of the local magma transfer dynamics might be linked to changes in the local stress field brought on during eruption this may potentially have been due to repeated dyke injections into etna s shallow plumbing system disrupting the early m 1 m 5 pathway and at the same time stabilizing the m 1 m 3 route as a dominant feeder this transfer of system feeding would reproduce the observed syn eruptive recharge and mixing in the weeks following eruption onset culminating in the eruption of the later set2 lavas

holocene climatic fluctuations in the gujarat alluvial plains based on a multiproxy study of the pariyaj lake archive western india abstract a sediment core from pariyaj lake from the vatrak river basin located at the desert margin in the gujarat alluvial plains of western india was investigated in a multidisciplinary aspect the goal was to reconstruct the palaeoclimate palaeoenvironment and tectonic history and to understand the role these factors played in the geomorphological evolution of the area during the holocene palaeoclimatic interpretations also shed light on the factors responsible for the rise and fall of the harappan civilisation the results obtained based on multiproxy studies show five climatic phases during the last 11 000 yr bp phase 1 11 000 cal yr bp represents a very humid climate and high precipitation discharge leading to high lake stand as attested by the high pollen concentration of semi evergreen tree taxa phytoliths belonging to cool and moist grasses and large proportion of algae marking the onset of holocene in phase 2 8000 to 9000 cal yr bp a significantly reduced yield of pollen phytoliths and aquatic algae indicates shrinkage of the lake phase 3 7630 cal yr bp shows moderate yield of pollen and phytolith pointing towards fluctuating precipitation conditions phase 4 5864 to 4680 cal yr bp shows very low pollen and phytolith counts indicating a very dry spell finally phase 5 4680 to 3500 cal yr bp shows a good density and diversity of flora the wet climate and high lake stand 11 000 cal yr bp 7630 cal yr bp and after 4680 cal yr bp are synchronous with the lacustrine marine and aeolian records of western india the contribution of winter precipitation at 7630 cal yr bp and after 4680 cal yr bp can be correlated with similar records from rajasthan lake decrease in the precipitation activity the low lake stand and the onset of dry climatic condition between 8000 and 9000 cal yr bp corresponds to a near global anomaly of this period another dry event between 5864 and 4680 cal yr bp documented in pariyaj lake record is synchronous with various proxy records of the mid late holocene afro asiatic monsoonal belt

reconstruction of the late quaternary environment of the lower luni plains thar desert india geomorphological processes in the thar desert of india are largely climate driven in the lower reaches of the river luni the only major drainage system in the thar desert a fluvio aeolian sequence was located at a site called khudala sediments of this sequence represented a variety of depositional environments namely aeolian fluvially reworked aeolian overbank deposits gravels and occasional evidence of pedogenesis this provided a good opportunity to study aeolian fluvial interaction in the region and for deducing climatic records from the luminescence dating standpoint these sequences offered a good opportunity for a comparative study of thermoluminescence tl blue green light stimulated luminescence bgsl and infrared light stimulated luminescence irsl on different mineral separates of identical provenance but deposited under different environments broadly within experimental errors the tl ages agreed with bgsl and irsl ages on aeolian sands but differed substantially in the case of fluvially reworked and proximally deposited sands and silts the sequence provided a record spanning more than 100 ka with an aeolian phase at 100 ka a channel activation phase between 70 and 30 ka and a phase of climate instability between 13 and 8 ka this appears consistent with the records of monsoon performance during this period which includes the younger dryas it is also inferred that during the last glacial epoch geomorphological processes in the thar both aeolian and fluvial were dormant largely on account of their relationship with the southwest monsoon copyright 2001 john wiley sons ltd

signatures of climate vs sea level change within incised valley fill successions quaternary examples from the texas gulf coast abstract the passive margin texas gulf of mexico coastal plain consists of coalescing late pleistocene to holocene alluvial deltaic plains constructed by a series of medium to large fluvial systems alluvial deltaic plains consist of the pleistocene beaumont formation and post beaumont coastal plain incised valleys a variety of mapping outcrop core and geochronological data from the extrabasinal colorado river and the basin fringe trinity river show that beaumont and post beaumont strata consist of a series of coastal plain incised valley fills that represent 100 kyr climatic and glacio eustatic cycles valley fills contain a complex alluvial architecture falling stage to lowstand systems tracts consist of multiple laterally amalgamated sandy channelbelts that reflect deposition within a valley that was incised below highstand alluvial plains and extended across a subaerially exposed shelf the lower boundary to falling stage and lowstand units comprises a composite valley fill unconformity that is time transgressive in both cross and down valley directions coastal plain incised valleys began to fill with transgression and highstand and landward translation of the shoreline paleosols that define the top of falling stage and lowstand channelbelts were progressively onlapped and buried by heterolithic sandy channelbelt sandy and silty crevasse channel and splay and muddy floodbasin strata transgressive to highstand facies scale architecture reflects changes through time in dominant styles of avulsion and follows a predictable succession through different stages of valley filling complete valley filling promoted avulsion and the large scale relocation of valley axes before the next sea level fall such that successive 100 kyr valley fills show a distributary pattern basic elements within coastal plain valleys can be correlated with the record offshore where cross shelf valleys have been described from seismic data falling stage to lowstand channelbelts within coastal plain valleys were feeder systems for shelf phase and shelf margin deltas respectively and demonstrate that falling stage fluvial deposits are important valley fill components signatures of both upstream climate change vs downstream sea level controls are therefore interpreted to be present within incised valley fills signatures of climate change consist of the downstream continuity of major stratigraphic units and component facies which extends from the mixed bedrock alluvial valley of the eroding continental interior to the distal reaches wherever that may be at the time this continuity suggests the development of stratigraphic units and facies is strongly coupled to upstream controls on sediment supply and climate conditions within hinterland source regions signatures of sea level change are critical as well sea level fall below the elevation of highstand depositional shoreline breaks results in channel incision and extension across the newly emergent shelf which in turn results in partitioning of the 100 kyr coastal plain valleys moreover deposits and key surfaces can be traced from continental interiors to the coastal plain but there are downstream changes in geometric relations that correspond to the transition between the mixed bedrock alluvial valley and the coastal plain incised valley channel incision and extension during sea level fall and lowstand with channel shortening and delta backstepping during transgression controls the architecture of coastal plain and cross shelf incised valley fills

geochemistry of the palitana flood basalt sequence and the eastern saurashtra dykes deccan traps clues to petrogenesis dyke flow relationships and regional lava stratigraphy recent studies of large mafic dyke swarms in the deccan traps flood basalt province india indicate that some of the correlative lava flows reached several hundred kilometers in length here we present field petrographic mineral chemical and whole rock geochemical including sr nd isotopic data on the palitana lava sequence and nearby dykes in the saurashtra region of the northwestern deccan traps these rocks are moderately evolved many with low ti nb characteristics we infer that most dykes are notably and systematically less contaminated by ancient continental crust than the palitana flows but four dykes are equally or significantly more contaminated with some of the most extreme sr nd isotopic compositions seen in the entire deccan traps initial end is as low as 18 0 a bhimashankar type and a poladpur type dyke are present several hundred kilometers from the type section of these magma types in the western ghats escarpment we find no geochemical correlations between the palitana sequence and three subsurface sequences in ne saurashtra containing abundant picritic rocks surface lavas previously studied from saurashtra or the western ghats sequence intriguingly the eastern saurashtra dykes cannot have been feeders to any of these lava sequences feeder dykes of these sequences may be located in southwestern or central saurashtra or in the dhule nandurbar dediapada areas across the gulf of cambay 200 300 km east of palitana our results indicate polycentric flood basalt eruptions not only on the scale of the deccan traps province but also within the saurashtra region itself

holocene paleoclimates of india we present a comprehensive summary of the available palaeoclimate records from india and compare the results from different proxies the results indicate i fluctuating lake levels during the early holocene the period of relatively higher lake levels from increased precipitation efficiency was reached only 7 2 6 0 cal kyr bp possibly due to increased contribution from winter rainfall ii the onset of aridity in nw india could have begun as early as 5 3 cal kyr bp subsequently there were multiple wet events but of shorter duration and smaller magnitude than during the mid holocene iii there is evidence of several short term climate events in the proxy record however in the absence of a rigorous chronological framework a detailed regional correlation is not possible at this stage finally a comparison between marine and terrestrial records indicates that episodes of strongest and weakest monsoon winds were not always associated with wettest and driest episodes respectively in the nw indian lakes

geochemistry of surface sediments from the arabian sea we report new geochemical data si al na k rb sr mn cu ni fe zn co and pb for 126 surficial sediments and base metal partition data for limited samples from the deep arabian sea and discuss the controls affecting these elemental concentrations the geochemical nature of and differences between sediments from three physiographically tectonically distinct regions have been identified the spatial resolution allows us to discern the various processes operative in the deep arabian sea during the holocene epoch r mode factor analysis on the geochemical data suggests that four dominant factors are responsible for the observed geochemical variations in the samples namely carlsberg ridge hydrothermal activity terrigenous contribution hydrogenous authigenic precipitates and biological contribution

new formulae for estimating lava flow volumes at mt etna volcano sicily a new data set of etna lava flows erupted since 1868 has been compiled from eight topographic maps of the volcano published at intervals since then volumes of 59 flows or groups of flows were measured from topographic difference maps most of these volumes are likely to be considerably more accurate than those published previously we cut the number of flow volumes down to 25 by selecting those examples for which the volume of an individual eruption could be derived with the highest accuracy this refined data set was searched for high correlations between flow volume and more directly measurable parameters only two parameters showed a correlation coefficient of 70 or greater planimetric flow area a 70 and duration of the eruption d 79 if only short duration 18 days flows were used flow length cubed l3 had a correlation coefficient of 98 using combinations of measured parameters much more significant correlations with volume were found dh had a correlation coefficient of 90 h is the hydrostatic head of magma above the vent and 92 where w is mean width and e is the degree of topographic enclosure and a combination of the two 97 these latter formulae were used to derive volumes of all eruptions back to 1868 to compare with those from the complete data set values determined from the formulae were on average lower by 16 dh 7 and 19

holocene sea level change on the southeast coast of australia a review a revised holocene sea level curve for the southeast coast of new south wales australia is presented based on a review of previously published geochronological results for fossil molluscs organi

chronology of late pleistocene environmental changes in the lower mahi basin western india sediments exposed in the lower mahi basin at the southern fringe of the thar desert rajasthan india provide evidence of three distinct depositional environments namely marine aeolian and fluvial these have been used to reconstruct late pleistocene environmental and tectonic history of the region infrared stimulated luminescence irsl chronology of the fluvial and aeolian litho units provides evidence of two major fluvial aggradation phases in the region corresponding to oxygen isotopic stages 5 and 3 the basal marine clay is inferred to represent the last interglacial stage and its present elevation at 20 m a s l is attributed to post depositional tectonism comparison of fluvial records from other regions indicates interhemispherically documented wetter phases during oxygen isotope stages 5 and 3 copyright 2000 john wiley sons ltd

luminescence dating of loess palaeosol sequences and coversands methodological aspects and palaeoclimatic implications abstract of the terrestrial archives loess palaeosol sequences provide a most complete record of climatic change this may be compared with the marine oxygen isotope stratigraphy and may help in the reconstruction of past atmospheric circulation patterns numerical chronometry of loess palaeosol sequences has generally been based on correlation of variations in climatic proxies such as magnetic susceptibility and particle sizes with marine isotopic data such chronometric assignments involve implicit assumptions about the constancy of sedimentation rates and particle fluxes through time this review presents a brief survey of the present status methodology outstanding problems and interpretational aspects of luminescence techniques and discusses the import of luminescence ages on global land sea correlations statistical analysis of the ages suggests episodicity of loess accumulation with extended periods of quiescence recent luminescence dating studies on closely spaced samples also lead to a similar inference luminescence ages imply high variability in loess sedimentation rates this conflicts with the assumption made in some current attempts to correlate loess records with marine records of almost constant particle fluxes a review of source proximal coversand deposits of northwest europe is also presented evidence of the onset of coversand deposition at 15 ka with a peak in accretion during the younger dryas and subsequent minor reactivation episodes is discussed

a quantitative approach for evaluating lava flow simulation reliability lavasim code applied to the 2001 etna eruption an edited version of this paper was published by agu copyright 2009 american geophysical union

fluvial response to late quaternary climate changes western india we review here the fluvial response to late quaternary climatic changes in the semi arid regions of western india i e the thar desert and its margins and maharashtra the rivers in the thar desert show a spectrum of environments from gravel bedload braided to ephemeral sand bed streams to sheet flows and sheet floods while those in the thar margin and maharashtra show dominantly two modes i e braided and meandering rivers the streams became defunct and aeolian sands were deposited during periods of relatively greater aridity in the thar desert and its margins incisions occurred during the wet phases in ois 1 it is inferred that changes in the monsoon precipitation led to relative changes in the discharge and sediment supply which were routed through those in the vegetation cover and played a key role in determining the fluvial style an inter comparison of the late quaternary alluvial deposits in the semi arid regions of western india suggests a continuum of fluvial environments interrelated through a precipitation gradient further a global comparison indicates that the response of semi arid western indian rivers was synchronous with the rivers in other climatic settings

lava flow volume and morphology from digitised contour maps a case study at mount etna sicily abstract the volume and morphology of a lava flow field can be measured by mapping and comparing the topography before and after lava emplacement contour maps are a widely available source of topographic data containing a record of the geomorphological changes at volcanoes due to lava emplacement this paper explores the use of 1 25 000 scale digitised contour maps for mapping two lava flows of diverse eruption history and morphology at mount etna sicily we find that subtracting dems created from these maps gives a good representation of volume and shape for thicker lava flows 10 m mean thickness in the case of the 1983 lava flow however thinner

the large and destructive 1669 ad eruption at etna volcano reconstruction of the lava flow field evolution and effusion rate trend the 1669 ad flank eruption was the most destructive event on etna volcano in historical times 700 bc and provided because of the presence of numerous quarries and subsurface data the opportunity for a unique case study in which we directly measured the thickness of the lava field moreover analysis of historical documents allowed reconstruction of the temporal evolution of the lava field and estimation of the average effusion rate one hundred and thirty eight thickness measurements acquired from field surveys and subsurface data allowed us to divide the lava field into 12 zones of homogenous mean thickness and to calculate a total lava volume of 607 105 106 m3 corresponding to an average effusion rate of 58 10 m3 s this new volume differs by 24 up to 64 from previously published values the temporal evolution of the cumulative volume and average effusion rate were reconstructed for the first fourteen days from field data and analysis of historical records a short initial phase was characterized by a rapid increase in effusion rate which reached a peak of 640 m3 s after 3 days this was followed by a longer phase in which the flow rate decreased the first 14 days were crucial for the development of the lava field and in this time it covered 72 of its final area and produced most of the damage thereafter the growth of a complex lava tube network promoted lava field lengthening to the city of catania 17 km away from the vent effusion rate trends like those of the 1669 eruption can be adopted for future investigations aimed at assessing the effects of similar events on etna s most highly urbanized area and at other effusive basaltic volcanoes

fluvial systems of the drylands of western india a synthesis of late quaternary environmental and tectonic changes abstract the fluvial systems and landscape of the drylands of western india have preserved evidence of late quaternary environmental and tectonic changes data on the fluvial systems of mainland gujarat saurashtra and kachchh have been synthesised to evaluate the roles of geological factors in the evolution of these drylands mainland gujarat is largely underlain by the flat alluvial plain and has a structurally controlled fluvial system that originates in the eastern uplands the fluvial system of mainland gujarat shows deeply incised valleys entrenched meanders extensively developed ravines and uplifted terraces which have preserved a late quaternary succession of continental fluvial and aeolian and marine sediments dating back to 125 ka marine sediments correspond to the transgressive phases of the last interglacial 125 ka and post glacial maximum 6 ka the overlying alluvial sediments suggest deposition by ephemeral rivers in varied fluvial depositional environments under a semi arid to sub humid climatic regime with periods of intense pedogenesis the sedimentation can be correlated with marine isotopic stages mis 5 and 3 the fluvial sediments are buried under a thick blanket of aeolian sediments which are indicative of enhanced dune building activity in the thar desert and are correlatable to the global arid phase of the last glacial maximum the post aeolian tectonic uplift triggered severe erosion of late pleistocene sediments and 40 50 m deep incised fluvial valleys were formed this erosional phase suggests a resumption of fluvial activity which coincided with the rapidly rising sea level on the west coast during the early holocene the holocene marine and fluvial aggradation was initiated within the incised fluvial valleys around 6 ka and continued uninterrupted until 2 ka these sediments now occur as raised valley fill terraces suggesting a late holocene uplift further corroborated by low to moderate seismic activity during historical times the landscape of saurashtra is marked by flat topped basaltic trappean ridges and a highly varied coastline where a narrow belt of low ridges and cliffs of miliolite limestones and other shore deposits are found the fluvial system of saurashtra shows a radial drainage pattern the channels have steep banks in the hilly regions and show significant deflections before meeting the sea evidence of last interglacial high sea levels 125 ka are found on the coastal cliffs of southern saurashtra in the form of oyster reefs and notches of various types which now occur at higher levels a net sea level rise of 7 m consistent with the global sea level estimates at 125 ka has been obtained by recent studies after decoupling the tectonic component dating of late pleistocene and holocene sea levels on this coast suggest continued uplift of saurashtra since 125 ka even though the sea level continued to fluctuate the holocene high sea submerged a considerable stretch of land including the okha rann on the northern saurashtra coast and isolated patches in and around the river mouths on the southern coast the short straight and parallel courses of rivers in the direction of tectonic slope incised and confined channel belts also suggest a strong component of tectonic uplift the continental sediments exposed in these river valleys have however remained uninvestigated leading to lack of palaeoclimatic data a remarkable control of structure on landscape evolution is depicted by the kachchh peninsula the fluvial system exhibits the characteristics of drainage flowing along tectonically provided slopes the overall drainage pattern of kachchh shows excellent correlation with n s trending transverse fault patterns the transverse fault system has brought out changes in the landscape of kachchh though the kachchh rift basin evolved along e w latitudinal faults the quaternary deposits occur in the form of miliolite limestones colluvial and alluvial fans fluvial sands and silts and rann sediments significant sedimentologic details on these sediments are lacking however the marine incursions seem to correlate with the adjacent saurashtra and mainland gujarat

current knowledge of etna s flank eruptions italy occurring over the past 2500 years from the iconographies of the xvii century to modern geological cartography abstract knowledge of etna s eruptions has been profoundly influenced by the illustrations though these can only provide limited information on the lava flows and their effects on the territory indeed the absence of iconographic sources or again the disparity between the physical reality and the illustrations has led to many gaps and uncertainties that have lasted for centuries this paper traces the progress of the representations of the historical eruptions of etna volcano from the earliest attempts in the 17th century be they iconographic documents or pictorial illustrations to the modern geological cartography of 21st century it seeks to reconstruct the evolution of the history and methods of representing etnean eruptions highlighting the crucial steps in the progress of knowledge on the historical flank eruptions the turning point in the long process of drawing and rendering the eruptions of etna came with the work of sartorius von waltershausen with the realization of the first geological map of the volcano at a 1 50 000 scale between 1836 and 1843 in this long history of the representations of eruptions begun in the 17th century sartorius cartography finally overcame the problem of rendering these events in space by inserting the notion of history in the map what now remained for those engaged in mapping the volcano was to solve the issue of defining the time of etna s historical lava flows this would be tackled only at the end of the 20th century with a multidisciplinary approach comprising stratigraphy historiographical studies and the dating of the lavas in this frame the present state of the knowledge of the flank eruptions occurring on etna in the past 2500 year has evidenced that during the greek roman and medieval epochs up to the 17th century flank eruptions commonly involved the middle lower slopes impacting mainly the south sector of the volcano with the location of the eruptive fissure sometimes below 1000 m of altitude this eruptive behavior of the volcano has been radically modified following the occurrence of the large 1669 eruptions since the opening of the fissures was mainly concentrated in the upper middle slopes between 1600 m and 2500 m a s l

lower eocene alluvial paleosols pedogenic development stratigraphic relationships and paleosol landscape associations abstract two kinds of cumulative floodplain paleosols red and grey paleosols formed on overbank deposits of the willwood formation in the sand coulee area of the bighorn basin wyoming although both kinds experienced down profile iron movement due to seasonal saturation of a clay rich a horizon the red paleosols were better drained and their b horizons were rubified various redoximorphic features indicate that the grey paleosols were poorly drained the red paleosols show progressive increases in the degree of profile development away from an associated channel sandstone a paleosol landscape relationship termed pedofacies by bown and kraus 1987 although the grey paleosols show relatively systematic changes in hydromorphy consistent pedofacies changes were not recognized furthermore no lateral relationship between the red and grey paleosols was observed these features suggest that because of the retarding effects of poor drainage on soil weathering poorly drained soils are not amenable to pedofacies modelling and that the landscape associations of well drained and poorly drained soils may be difficult to document without unusually extensive exposures results of this study also show that the pedofacies model is limited by sediment accumulation rates and the kind of fine grained facies on which paleosols developed although readily observable in sand coulee pedofacies are difficult to recognize in the elk creek area where accumulation rates were approximately half as rapid as in sand coulee the attainment of steady state conditions is believed to have obscured pedofacies in the elk creek area finally pedofacies are only developed on true overbank deposits which in the willwood formation and probably many other ancient alluvial sequences make up only a fraction of the fine grained deposits only immature soils formed on the remainder of the fine grained facies because they were deposited very rapidly as a result of channel avulsion

late quaternary climate and seismicity in the katrol hill range kachchh western india abstract a channel fill sequence in the upper catchment of the khari river in the south of the katrol hill fault khf has been investigated to understand the role of climate and tectonics in the evolution of fluvial landforms detailed sedimentology and limited optical chronology suggest that the channel incision occurred during weak summer monsoon prior to 19 9 ka and is attributed to the activity along the khf and its subsidiary faults the post glacial to early holocene was a phase of landscape stability subdued tectonics which persisted until around 7 1 ka particularly between 9 4 ka and 7 1 ka an enhanced monsoon activity is inferred a renewed phase of uplift is suggested after 7 1 ka that probably continues till present

climatic imprints in quaternary valley fill deposits of the middle teesta valley sikkim himalaya abstract quaternary alluvial sediments occur as distinct terrace and fan deposits in the middle teesta valley in the belt between the main central thrust and the main boundary thrust in the sikkim himalaya these sequences are characterized by lithofacies deposited by braided river channels debris flows and hyperconcentrated flows the channel flow deposits constitute relatively well sorted well imbricated and clast supported gravels with coarse to medium sand matrix mostly poorly sorted weakly imbricated to disorganized matrix supported pebble to boulder gravels with silty sand represent debris flow deposits hyperconcentrated flow deposits consist of clast supported poorly developed sorted polymodal gravel facies with poorly developed imbricated fabric and generally occupy the lower parts of the terrace and fan sequences the alternation from hyperconcentrated flow to channel flow deposits is predominant in the sequence and is possibly the response to different climate modes the high discharge and supply of sediments as well as the dispersal and deposition of these materials in the trunk stream is attributed to millennial multimillennial climatic perturbations during the quaternary climate change has a dominant role in the valley aggradation and incision cycle

scour fill and burial depth of coarse material in gravel bed streams scour fill and burial depths of coarse particles were examined in two ephemeral streams using magnetically tagged particles and scour chains the burial depth varied within a bedform and from one bedform to another the maximum burial depth was recorded in bars but differences in the mean burial depth in the pools bar and thalweg were insignificant mean burial depth was three to six times the median size of material on bar surfaces and ten to thirty times that in the pools and thalweg more than eighty per cent of the tagged particles which were located on or close to the bed surface moved in each event although previously buried particles were moved by flood events others which were initially exposed remained stationary on the surface or were buried in situ the data indicate that the mean burial depth was intermediate between the mean depths of scour and fill deeply buried particles probably reflect the development of scour holes during flood flows aggradation and degradation changed the recorded burial depth relative to the local bed surface of stationary tracer particles these observations indicate that scour and fill processes during a flow event are sporadic and change with water discharge

aggradation history and luminescence chronology of late quaternary semi arid sequences of the sabarmati basin gujarat western india the gujarat alluvial plain in the semi arid desert margin of the thar desert contains a record of continental quaternary sequences these sequences were built by drainages originating in the aravalli hills and flowing westward into the indian ocean stratigraphic studies of a part of the late quaternary succession in the sabarmati basin have resulted in a fourfold lithostratigraphic scheme the waghpur formation conglomeratic member sand member the mahesana formation lower heterolithic member upper sand member the akhaj formation and the sabarmati formation facies analysis distribution of conglomerates and cross bed azimuths of the clastic facies of the waghpur formation were used to infer ne sw trending semi arid alluvial fans the deposition of the overlying heterolithic member took place in ephemeral streams influenced by episodic flows and aeolian reworking the upper member of the mahesana formation represents aeolian and older levee deposits feasibility studies of thermoluminescence tl and infra red stimulated luminescence irsl dating on the sabarmati succession yielded stratigraphically consistent ages ranging from 5 ka to 300 ka for two samples tl ages on quartz and irsl ages on feldspar separates were consistent these results together with the stratigraphic and petrographic data reveal the following events in the accumulation history of the sabarmati sequence 1 1 significant aggradation at 300 ka gravel sand and at 58 ka sand and 2 2 pedogenesis bracketed to 58 39 ka the sabarmati river in its middle stretches follows a regional slope deviatory course interpreted previously to be a neotectonic adjustment within the cambay graben our chronological data suggest that this adjustment occurred possibly within the past 39 ka

the case of the 1981 eruption of mount etna an example of very fast moving lava flows 1 mount etna despite being an extremely active volcano which during the last 400 years has produced many lava flow flank eruptions has rarely threatened or damaged populated areas the reconstruction of the temporal evolution of potentially hazardous flank eruptions represents a useful contribution to reducing the impact of future eruptions by and analyzing actions to be taken for protecting sensitive areas in this work we quantitatively reconstructed the evolution of the 1981 lava flow field of mt etna which threatened the town of randazzo this reconstruction was used to evaluate the cumulated volume the time averaged discharge rate trend and to estimate its maximum value the analysis was conducted by comparing pre and post eruption topographic surfaces extracted by processing historical photogrammetric data sets and by utilizing the eruption chronology to establish the lava flow front positions at different times an unusually high discharge rate for etna of 640 m3 s was obtained which corresponds well with the very fast advance rate observed for the main lava flow a comparison with other volcanoes presenting high discharge rate was proposed for finding a clue to unveil the 1981 etna eruptive mechanism a model was presented to explain the high discharge rate which includes an additional contribution to the lava discharge caused by the interception of a shallow magma reservoir by a dike rising from depth and the subsequent emptying of the reservoir

the role of porosity on the engineering geological properties of 1669 lavas from mount etna abstract a comprehensive laboratory characterization of volcanic rocks belonging to the 1669 lava flow of mount etna recognized as one of the largest and most catastrophic event ever occurred is presented herein with the aim of investigating on their peculiar mechanical attitude the multi disciplinary approach proposed herein pointed out that although originated by the same eruptive event 1669 trachybasaltic lavas are characterized by relevant differences in porosity and rock fabric from both the qualitative and quantitative points of view this is an interesting aspect because such rocks are quarried for the production of high quality material to be employed for engineering geological purposes even in the val di noto unesco world heritage site in this perspective their detailed characterization is an essential practice even preparatory for the engineering geological use to this purpose this paper provides a focus on the laboratory investigation of these rocks which according to three different porosity classes underwent petrographic physical mechanical and seismic analyses interesting statistical correlations allowed understanding the mutual dependence of the main engineering geological parameters highlighting how porosity through both vesicles and microcracks plays a leading role from the engineering geological point of view achieved results provide a scientific casuistry on this topic and are a reliable reference for studies on similar rock types worldwide since lavas are among the most used rock materials in the engineering geological practice

late quaternary geomorphic evolution of the lower narmada valley western india implications for neotectonic activity along the narmada son fault geomorphic data combined with stratigraphic studies provide significant information to constrain timing and amount of fault movement the lower narmada valley lies astride the narmada son fault nsf an important ene wsw trending tectonic element responsible for the current intraplate seismicity being experienced in the central part of the indian plate varying nature and degree of tectonic movements along the nsf during late pleistocene and holocene have produced four geomorphic surfaces in the lower narmada valley the alluvial plain s1 ravine surface s2 a gravelly fan surface s3 and the valley fill terrace surface s4 two major phases of tectonic movements in a compressive stress regime are recorded along the nsf slow synsedimentary subsidence of the basin during late pleistocene due to differential movement followed by inversion of the basin during the holocene marked by differential uplift along the nsf the study suggests that the inversion of the basin is in response to the significant increase in the intensity of compressive stresses in the indian plate mainly during the early holocene the present incisive drainage and recent seismic activity indicate that the compressive stresses continue to accumulate along the nsf due to continued northward movement of the indian plate

major and trace element geochemistry of bay of bengal sediments implications to provenances and their controlling factors major and trace elements of sediments from a 13 m long piston core sk187 pc33 from the western bay of bengal have been investigated in this study to infer about the changes in provenances and related controlling factors during the last glacial interglacial period factor analysis of these geochemical dataset ascertains dominant role of riverine supply of sediments in regulating the geochemistry of sk187 pc33 sediments the al normalized major k and ti and trace elemental cu and cr ratios of these marine sediments fall within the ranges observed for their major provenances viz ganga brahmaputra and the godavari krishna gk rivers and depth profiles of these ratios showed significant variations with synchronous excursion at around the last glacial maxima lgm implying a change in their provenances with relatively reduced himalayan contribution during this climatic event relatively higher cia and ti ca ratios with lower k al ratios of these sediments during the holocene hint intense chemical weathering in the river basins in response to strengthened monsoon during this period inverse model calculation of al normalized elemental ratios of the sediments estimated an average sediment contribution of 66 13 and 34 13 from the himalayan and the peninsular indian rivers to the core site respectively consistent with the depth profiles of elemental ratios the estimated sediment contributions from the himalayan rivers are observed to decrease by 20 from the himalayan rivers particularly that of the ganga to the studied location during the lgm lowering of sediment supply from the himalaya ganga during the lgm is due to weakening of south west monsoon and reduction in available exposure area for weathering due to extent of glacier cover outcomes of this study underscore the strong linkage between erosion and climate

geochronology of palaeolithic cultures in the hiran valley saurashtra india abstract the u and th concentrations of 16 miliolite samples from the hiran valley in saurashtra ranged from 0 3 to 2 14ppm and 0 12 to 0 82ppm respectively the 234 u 238 u activity ratio ranged from 1 09 to 1 16 with a mean of 1 12 0 02 it agrees well with the seawater value of 1 14 0 02 within the quoted errors nine of the samples were datable by the 230 th 234 u method and the ages ranged from 56 8 to 190 kyr the problem of chronology of palaeolithic artifacts is interlinked with the miliolite and other coastal formations the present investigations permit the development of a chronological framework for the palaeolithic cultures in the hiran valley in particular and generally in saurashtra peninsula on the basis of radiometric dates and relative chronology the lower palaeolithic cultures fall in a time bracket of 190 69 kyr bp the middle palaeolithic industry is much older than 56 8 kyr bp the dates obtained for the lower palaeolithic cultures are perhaps the oldest reported to date

analysis of the 2001 lava flow eruption of mt etna from three dimensional mapping 1 the 2001 etna eruption was characterized by a complex temporal evolution with the opening of seven eruptive fissures each feeding different lava flows this work describes a method adopted to obtain the three dimensional geometry of the whole lava flow field and for the reconstruction based on topographic data of the temporal evolution of the largest lava flow emitted from a vent located at 2100 m a s l preeruption and posteruption digital elevation models dem were extracted from vector contour maps comparison of the two dems and analysis of posteruption orthophotos allowed us to estimate flow area thickness and bulk volume additionally the two dimensional temporal evolution of the 2100 flow was precisely reconstructed by means of maps compiled during the eruption these data together with estimates of flow thickness allowed us to evaluate emitted lava volumes and in turn the average volumetric flow rates the analysis performed in this paper provided a total lava bulk volume of 40 1 106 m3 for the whole lava flow field most of which emitted from the 2100 vent 21 4 106 m3 the derived effusion rate trend shows an initial period of waxing flow followed by a longer period of waning flow this is in agreement not only with the few available effusion rate measurements performed during the eruption but also with the theoretical model of wadge 1981 for the temporal variation in discharge during the tapping of a pressurized source

fluvial response to tectonic activity in an intra continental dryland setting the neales river lake eyre central australia abstract geomorphological studies in the centre of the australian continent have emphasised the antiquity of the australian landscape typically considered tectonically stable evidence from the neales river on the western shore of lake eyre indicates that mild epeirogenic forces have deformed sediments of miocene age deformed bedding planes small scale folds and fracture systems reflect consistent miocene and younger tectonic activity in central and southern australia this compression was mild resulting in broad gently plunging folds these folds are evident in the miocene strata but not in the overlying quaternary strata elsewhere in the study area the landscape has been rearranged to preserve features in the geomorphic record that indicate a second phase of tectonic activity in the early to mid pleistocene these include stream diversions preserved on alluvial fans and floodplains formed downstream of faults

sedimentology geochemistry and osl dating of the alluvial succession in the northern gujarat alluvial plain western india a record to evaluate the sensitivity of a semiarid fluvial system to the climatic and tectonic forcing since the late marine isotopic stage 3 abstract the alluvial successions in the northern gujarat alluvial plain western india have been investigated for reconstructing the climatic fluctuations during the last 40 ka alluvial architecture and geochemical proxies indicate prevalence of a strengthened indian summer monsoon ism with fluctuations between the late marine isotopic stage 3 mis 3 37 ka to the early mis 2 27 ka a gradual onset of aridity declining ism after 27 ka with peak aridity at 22 ka is observed a gradual strengthening of ism at around 18 and 12 ka followed by a short reversal in ism intensity between 12 and 11 ka is attributed to the younger dryas yd cooling event the aeolian sand sheet dated to 6 and 3 5 ka represents the onset of regional aridity following this a short lived humid phase was observed after 2 ka which includes the medieval warm period mwp the study suggests that the variability in the ism to the latitudinal migration of the inter tropical convergence zone was caused by insolation driven cooling and warming events in the north atlantic the incision of the valley fill alluvium occurred in two distinct phases the older incision phase occurred after 11 ka and before 6 ka whereas the younger incision phase that led to the development of present day topography is bracketed between 3 5 ka and before 1 ka the older incision phase is ascribed to the early to mid holocene enhanced ism climatically driven whereas the younger incision seems to be modulated by the activation of basement faults tectonically driven

the length of channelized lava flows insight from the 1859 eruption of mauna loa volcano hawai i a r t i c l e i n f o the 1859 eruption of mauna loa volcano hawai i produced paired a and p hoehoe ows of exceptional length 51 km the a ow eld is distinguished by a long n36 km and well de ned p hoehoe lined channel indicating that channelized lava remained uid to great distances from the vent the 1859 eruption was further unusual in initiating at a radial vent on the volcano s northwest ank instead of along the well de ned rift zone that has been the source of most historic activity as such it presents an opportunity both to examine controls on the emplacement of long lava channels and to assess hazards posed by future ank eruptions of mauna loa here we combine evidence from historical chronicles with analysis of bulk compositions glass geothermometry and microlite textures of samples collected along the 1859 lava ows to constrain eruption and ow emplacement conditions the bulk compositions of samples from the a and p hoehoe ow elds are bimodally distributed and indicate tapping of two discrete magma bodies during eruption samples from the p hoehoe ow eld have bulk compositions similar to those of historically erupted lavas b8 wt mgo lava that fed the a channel is more primitive n8 wt mgo nearly aphyric and was erupted at high temperatures 1194 1216 c we suggest that the physical properties of proximal channel fed lava i e high temperature low crystallinity and low bulk viscosity promoted both rapid ow advance and development of long p hoehoe lined channels critical for the latter was the large temperature decrease 50 c required to reach the point at which plagioclase and pyroxene started to crystallize the importance of phase constraints are emphasized by our dif culty in replicating patterns of cooling and crystallization recorded by high temperature eld samples using common models of ow emplacement placement of the 1859 eruption within the context of historic activity at mauna loa suggests that the formation of radial vents and eruptions of high temperature magma may not only be linked but may also be a consequence of periods of high magma supply e g 1843 1877 flank eruptions could therefore warrant special consideration in models and hazard mitigation efforts

the 1669 eruption at mount etna chronology petrology and geochemistry with inferences on the magma sources and ascent mechanisms analysis of the petrochemical characters of the 1669 etnean lavas shows that they can be grouped into two sets set1 lavas were erupted from 11 to 20 march and are more primitive in composition than set2 erupted later until the end of activity both sets may be interpreted as the result of crystallization under different conditions of two primary magmas which are compositionally slightly distinct and which fractionate different volumetric proportions of minerals to explain why more mafic lavas set1 were erupted earlier than more acid ones set2 we argue that new deeper magma rose up into a reservoir where residing magma was fractionating density calculations demonstrate that new magma is less dense and may originate a plume rapidly rising through the residing magma which is cooler and more volatile depleted than the new magma calculations of uprise velocity assuming laminar flow are consistent with this hypothesis

life at the top of the greenhouse eocene world a review of the eocene flora and vertebrate fauna from canada s high arctic early middle eocene ca 53 38 ma sediments of the eureka sound group in canada s arctic archipelago preserve evidence of lush mixed conifer broadleaf rain forests inhabited at times by alligators turtles and diverse mammals including primates tapirs brontotheres and hippo like coryphodon this biota reflects a greenhouse world offering a climatic and ecologic deep time analog of a mild ice free arctic that may be our best means to predict what is in store for the future arctic if current climate change goes unchecked in our review of the early middle eocene arctic flora and vertebrate fauna we place the arctic fossil localities in historic geographic and stratigraphic context and we provide an integrated synthesis and discussion of the paleobiology and paleoecology of these eocene arctic forests and their vertebrate inhabitants the abundance and diversity of tapirs and plagiomenids both rare elements in midlatitude faunas and the absence of artiodactyls early horses and the hyopsodontid condylarth hyopsodus well represented at midlatitude localities are peculiar to the eocene arctic the eocene arctic macrofloras reveal a forested landscape analogous to the swamp cypress and broadleaf floodplain forests of the modern southeastern united states multiple climate proxies indicate a mild temperate early middle eocene arctic with winter temperatures at or just above freezing and summer temperatures of 20 c or higher and high precipitation at times this high precipitation resulted in freshwater discharge into a nearly enclosed arctic ocean basin sufficient to cause surface freshening of the arctic ocean supporting mats of the floating fern azolla fluctuating arctic ocean sea level due to freshwater inputs as well as tectonics produced temporary land bridges allowing land plants and animals to disperse between north america and both europe and asia

mid holocene sedimentation and landscape evolution in the western great rann of kachchh india abstract this study is an attempt to reconstruct the history of sedimentation and landform evolution in the western great rann of kachchh field stratigraphy sedimentology geochemistry optical and radiocarbon dating suggest dominance of tidal flat sedimentation with subordinate contribution coming from the southern draining streams during 5 5 to 2 ka variability in the geochemical proxies are interpreted as a surrogate for tidal energy viz zr and cr which along with the major elemental ratios tio 2 al 2 o 3 and k 2 o al 2 o 3 indicate enhanced tidal energy condition during 5 5 to 5 ka and around 3 ka a close correspondence of the major and trace elements with those of the indus river sediment and the dominance of illite suggest the indus river was a major contributor for western rann sedimentation during the mid holocene these sediments were routed through the kori creek during marginally high sea level until around 2 2 ka and the present landscape was largely sculptured after the 1819 allah bund earthquake

characteristics of deformation and past seismicity associated with the 1819 kutch earthquake northwestern india the 1819 earthquake in kutch northwestern india is one of the most significant events to have occurred in a plate interior setting despite being the second largest among the stable continental region scr earthquakes this event has not been analyzed within the context of present day understanding of earthquake seismology coseismic changes related to this earthquake include massive ground deformation in a wide low lying tidal flat area although detailed historic accounts of this earthquake exist many questions regarding the mode of deformation and the seismic history of the region remain unresolved we explored the region nearly 180 years after the earthquake and the information gathered adds to our understanding of this event and provides a fresh perspective on this unique intraplate seismogenic zone a 90 km long tract of elevated land with a peak height of 4 3 m is the most visible surface expression of this earthquake we surveyed and analyzed the morphological features of this scarp and also carried out exploratory trenching in this region the scarp morphology is suggestive of a growing fold related to a buried north dipping thrust rather than a discrete fault that could have resulted from a surface rupture the extensive liquefaction field associated with the earthquake offered an ideal setting to explore the paleoearthquake history age data of liquefaction features suggest that a previous event of comparable size must have occurred 800 1000 years ago seismic activity appears to be related to the reactivation of an ancient rift in a stress regime that is dominated by nearly north south compression

mid holocene climate and land sea interaction along the southern coast of saurashtra western india abstract the relict mudflat from the southern saurashtra coast of gujarat was investigated using geochemical and palynological analyses supported by radiocarbon dating to understand whether climate fluctuations and sea level operated in tandem during mid holocene the study revealed that the saurashtra coast experienced relatively wet climatic conditions with simultaneous occurrence of marginally high sea level between 4710 and 2825 cal yr bp subsequently a gradual onset of aridity and lowering of the sea level was observed between 2825 and 1835 cal yr bp and further a slight decrease in aridity is observed after 1835 cal yr bp the present day coastal configuration was probably achieved after around 1500 cal yr bp considering the tectonic instability of saurashtra coast land level changes the effective mid holocene sea level was estimated to be 1 m higher than the present the study demonstrates that sea level changes climate variability and land level changes were coupled during the mid holocene

arcticanodon dawsonae a primitive new palaeanodont from the lower eocene of ellesmere island canadian high arctic a new genus and species of palaeanodont arcticanodon dawsonae is based on a single lower jaw fragment from lower eocene wasatchian strata of the margaret formation eureka sound group on central ellesmere island nunavut the new taxon is more derived than early paleocene escavadodontidae but lacks derived traits of metacheiromyidae it is therefore most similar to primitive epoicotheriids although the similarities are essentially in plesiomorphic features consequently arcticanodon dawsonae is classified as palaeanodonta incertae sedis pending discovery of more complete specimens resume un nouveau genre et une nouvelle espece de palaeanodonta arcticanodon dawsonae est base sur un seul fragment de mandibule inferieure provenant des strates de la formation de margaret eocene inferieur wasatchien du groupe d eureka sound au centre de l ile d ellesmere au nunavut le nouveau taxon est plus derive que escavadodontidae du paleocene precoce mais il ne presente pas les traits derives de metacheiromyidae il ressemble donc plus aux epoicotheriides primitifs bien que les similitudes se presentent surtout dans les caracteristiques plesiomorphiques par consequent arcticanodon dawsonae est classe en tant que palaeanodonta incertae sedis en attendant la decouverte de specimens plus complets traduit par la redaction rose et al 763

late pleistocene holocene uplift driven terrace formation and climate tectonic interplay from a seismically active intraplate setting an example from kachchh western india abstract fluvial terrace formation is often regulated by external forcings like climate tectonic and eustatic changes these terraces particularly in a dryland environment preserves the discrete signatures of these external forcings thus enabling us to reconstruct the fluvial response to the late quaternary palaeoenvironmental changes and factors governing them the present study focuses on reconstructing the aggradation incision phases in the lotia river which is located in the eastern segment of the northern hill range nhr of the kachchh peninsula the lotia river drains through mesozoic rocks before cutting across the kachchh mainland fault kmf and finally debouch in the banni plains reconstruction based on tectonic geomorphology sedimentology sediment geochemistry mineral magnetic and osl chronology suggests the fluvial response to monsoon variability archived during the last 15 ka the time frame was also marked by incision enhanced by uplift along the kmf which led to strath terrace formation the accommodation space thus created was filled by an aggradational event between 14 8 ka and 10 6 ka sedimentological and geochemical parameters have also suggested that the time period between 12 5 ka and 11 5 ka showed a decline in the monsoon strength which coincides with younger dryas it has been observed that the sediments spanning between 10 6 ka and 7 8 ka are absent from the archive which is most likely the manifestation of the early holocene optimum that led to severe erosional processes the period between 7 8 ka and 3 3 ka is marked as another aggradational phase with fluctuating climatic conditions at 3 3 ka the region has experienced an incision of 4 m which led to the formation of holocene terrace t 1 most likely due to tectonic uplift during the last 3 3 ka another pulsative uplift has occurred which led to the formation of unpaired holocene terrace t 2 along with tilting of the lotia basin based on the osl chronology of bedrock strath terrace we reported a minimum uplift rate of 1 04 mm a for the eastern kmf during the late pleistocene holocene period hinting seismically active nature of the kmf during this period the terrace formation in the eastern northern hill range is mostly regulated by tectonic uplifts along the kmf

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

mid late holocene monsoonal records from the partially active mudflat of diu island southern saurashtra gujarat western india abstract the mid late holocene period is seldom known for any drastic climatic perturbations but witnessed significant anthropogenic growth and thus has been a subject of scientific importance in this study sediment core raised from an active mudflat of diu island southern saurashtra coast gujarat with a climatic history for the last 4100 yr bp has been investigated based on geochemical proxies productivity weathering and detrital results indicate warm and humid conditions during holocene climate optimum hco between 4105 and 2640 cal yr bp as a result of monsoon intensification followed by an arid conditions between 2640 and 1930 cal yr bp later during 1930 355 cal yr bp the region regained warm and humid conditions the mudflat responded in accordance with the global climatic perturbations during last 2000 yr witnessing signatures of roman warm period and medieval warm period additionally cool and humid climatic conditions persisted during little ice age followed by modern warming period witnessed during last 300 yr

abrupt changes in the asian southwest monsoon during the holocene and their links to the north atlantic ocean during the last ice age the indian ocean southwest monsoon exhibited abrupt changes that were closely correlated with millennial scale climate events in the north atlantic region1 2 3 suggesting a mechanistic link in the holocene epoch which had a more stable climate the amplitude of abrupt changes in north atlantic climate was much smaller and it has been unclear whether these changes are related to monsoon variability here we present a continuous record of centennial scale monsoon variability throughout the holocene from rapidly accumulating and minimally bioturbated sediments in the anoxic arabian sea our monsoon proxy record reveals several intervals of weak summer monsoon that coincide with cold periods documented in the north atlantic region4 including the most recent climate changes from the medieval warm period to the little ice age and then to the present we therefore suggest that the link between north atlantic climate and the asian monsoon is a persistent aspect of global climate

finding of an historical document describing an eruption in the nw flank of etna in july 1643 ad timing location and volcanic products the eruptive activity of etna volcano is well known in detail due to the integration of numerous geological and historical investigations the study of historical sources of the volcano s activity started in the sixteenth century and has been reported in several catalogues of the eruptions published mainly in the eighteenth and nineteenth centuries we have found a new document written in 1643 by the fiscal prosecutor of the high court for the viceroy of sicily in which he reported earthquakes occurring in the small town of troina the document also describes an eruption taking place in the bronte region of etna between 18 and 28 of july that was previously unknown in current historical catalogues even those compiled by recent historiographical studies this eruption clearly produced the volcanic products outcropping in the upper nw flank shown on the new geological map of etna as the val di cannizzola lava flow the july 1643 eruption was a brief event with the emission of a roughly 2 7 km long lava flow of very low volume 3 4 106 m3 it occurred in a period characterised instead by long lasting and high lava volume eruptions that preceded the large and destructive 1669 eruption the main event that has occurred on etna in historical time

reconstruction of the variability of the southwest monsoon during the past 3 ka from the continental margin of the southeastern arabian sea from temporal variation in 18o in globigerinoidesruber and g sacculifer and geochemical indices of weathering erosion chemical index of alteration al and ti we infer rapid southwest monsoon swm deterioration with dwindling fluvial and detrital fluxes at ca 450 650 1000 and 1800 2200 cal a bp during the late holocene we have evaluated the role of solar influx reconstructed and high latitude climate variability archived in grip and gisp 2 cores on swm precipitation broadly our 18o climate reconstruction is concordant with grip and gisp 2 and supports a teleconnection through atmospheric connection between the swm and the north atlantic climate albeit temporal extents of the little ice age and medieval warm period from high latitude are not entirely coeval moreover there is a humid climate and enhanced precipitation during the terminal stages of the little ice age the medieval warming ca ad 800 1300 is not synchronous either and is punctuated by an arid event centred at 1000 a bp although the delineation of the specific influence of solar influx on swm precipitation is elusive we surmise that swm precipitation is a complex phenomenon and local orography along southwestern india may have a role on the entrapment of moisture from the southwest trade winds when these hit land copyright 2009 john wiley sons ltd

fluvial geomorphology and neotectonic activity based on field and gpr data katrol hill range kachchh western india abstract the largely rocky and rugged landscape of the katrol hill range composed of mesozoic rocks and structurally controlled occurrences of quaternary sediments is delimited to the north by north facing range front scarps of the seismically active e w trending katrol hill fault khf the landscape and drainage characteristics of the katrol hill range are documented together with ground penetrating radar gpr investigations along the khf to delineate its nature for understanding neotectonic activity in the contemporary tectonic setting the overall geomorphology is controlled by the south oriented tilt block structure of the range indicated by its pronounced influence on the morphology and drainage network the drainage comprises north flowing and south flowing rivers with the drainage divide located close to the northern edge of the range which also marks the highest topographic elevations the narrow zone between the crest line and the drainage divide has been identified as the zone of gorges where gorges and deeply incised fluvial valleys have been formed within quaternary sediments by the various north flowing streams the quaternary sediments consist of bouldery colluvial deposits in front of the range front scarps valley fill miliolites and alluvial deposits of late pleistocene age within the back valleys and scarp derived colluvium forming the youngest deposit based on the geomorphic and stratigraphic evidence three major phases of quaternary tectonic uplift in the katrol hill range are inferred the oldest pre miliolite phase middle pleistocene was followed by a prominent phase of fluvial incision with formation of gorges during early holocene and then by the last one during late holocene continuing at present uplift of the range occurred in well marked phases during the quaternary in response to differential uplift along the khf under an overall compressive stress regime gpr investigations at selected sites show that the khf is a steep south dipping reverse fault near the surface which becomes vertical at depth this suggests neotectonic reactivation of the khf under a compressive stress regime responsible for active southward tilting of the katrol hill range

climatic and hydrologic oscillations in the owens lake basin and adjacent sierra nevada california oxygen isotope and total inorganic carbon values of cored sediments from the owens lake basin california indicate that owens lake overflowed most of the time between 52 500 and 12 500 carbon 14 14 c years before present b p owens lake desiccated during or after heinrich event h1 and was hydrologically closed during heinrich event h2 the magnetic susceptibility and organic carbon content of cored sediments indicate that about 19 sierra nevada glaciations occurred between 52 500 and 23 500 14 c years b p most of the glacial advances were accompanied by decreases in the amount of discharge reaching owens lake comparison of the timing of glaciation with the lithic record of north atlantic core v23 81 indicates that the number of mountain glacial cycles and the number of north atlantic lithic events were about equal between 39 000 and 23 500 14 c years b p

early eocene rodents mammalia from the eureka sound group of ellesmere island canada rodents are a minor element in the early eocene terrestrial fauna from the eureka sound group of ellesmere island nevertheless at least five taxa can be recognized all members of the family ischyromyidae two are paramyines of which one is described as paramys hunti sp nov three of the rodents are microparamyines microparamys bayi sp nov and two species of the new genus strathcona s minor sp nov and s major sp nov the paramyines are holarctic in distribution in the early eocene but the microparamyines are known only from north america and europe the arctic microparamyinae provide the first clearly documented case for an early cenozoic mammalian taxon having a north american origin and later dispersal into europe across a north atlantic terrestrial biogeographic province

fluvial landforms and their implication towards understanding the past climate and seismicity in the northern katrol hill range western india abstract the tectonically active kachchh peninsula in western india lies in the southwest monsoon trajectory and hence provides a rare opportunity to decipher the temporal changes in climate tectonics interaction in the evolution of the fluvial landforms reconstructions based on geomorphology sedimentology and geochemistry supported by optical chronology suggest that the fluvial aggradation in the region was initiated during the onset of the indian summer monsoon ism after the last glacial maximum lgm the sedimentary characteristics and major elemental concentrations suggest that the sediments are dominated by fluvially reworked miliolites with subordinate contribution from the mesozoic sandstones and shales and were deposited with the initiation of the ism after the lgm temporal changes in facies architecture and major element concentrations suggest a progressive strengthening of the monsoon between 17 and 12 ka this was succeeded by an overall strengthened ism phase with fluctuations after 12 ka and based on the morphology of the fluvial landforms two major events of enhanced uplift can be suggested the geomorphic expression of the older uplift event dated to 17 ka is represented by the beveled mesozoic bedrock surfaces which accommodated the post lgm valley fill aggradation the younger event of enhanced uplift which is assigned to

simulations of measures to control lava flows we evaluated the quantitative effects of artificial barriers water cooling and guiding channels on lava flow using the lava simulation program lavasim lava flow is basically subject to the topography around the path effusive rate and viscosity to prevent damage due to lava flow we conducted experiments in controlling the flow direction velocity and temperature the simulation demonstrated that artificial barriers can successfully change the direction of a lava flow and is more effective when placed nearly parallel to the flow direction at a point where the topography is not very steep while a barrier placed perpendicular to the flow direction can only stop the flux temporarily ultimately allowing the solidified crust to accumulate and causing the following mass to go over the barrier the water cooling trial was also effective in controlling the direction and temperature although the amount of water was as much order as 105 m3 the guiding channels successfully control the direction and inundated area but only in local areas

fluvial responses to climate and sea level change a review and look forward summary fluvial landforms and deposits provide one of the most readily studied quaternary continental records and alluvial strata represent an important component in most ancient continental interior and continental margin successions moreover studies of the long term dynamics of fluvial systems and their responses to external or allogenic controls can play important roles in research concerning both global change and sequence stratigraphy as well as in studies of the dynamic interactions between tectonic activity and surface processes these themes were energized in the final decades of the twentieth century and may become increasingly important in the first decades of this millennium this review paper provides a historical perspective on the development of ideas in the fields of geomorphology quaternary geology vs sedimentary geology and then summarizes key processes that operate to produce alluvial stratigraphic records over time scales of 103 106 years of particular interest are changes in discharge regimes sediment supply and sediment storage en route from source terrains to sedimentary basins as well as changes in sea level and the concept of accommodation late quaternary stratigraphic records from the loire france mississippi usa colorado texas usa and rhine meuse the netherlands rivers are used to illustrate the influences of climate change on continental interior rivers as well as the influence of interacting climate and sea level change on continental margin systems the paper concludes with a look forward to a bright future for studies of fluvial response to climate and sea level change at present empirical field based research on fluvial response to climate and sea level change lags behind a the global change community s understanding of the magnitude and frequency of climate and sea level change b the sequence stratigraphic community s desire to interpret climate and especially sea level change as forcing mechanisms and c the modelling community s ability to generate numerical and physical models of surface processes and their stratigraphic results a major challenge for the future is to catch up which will require the development of more detailed and sophisticated quaternary stratigraphic sedimentological and geochronological frameworks in a variety of continental interior and continental margin settings there is a particular need for studies that seek to document fluvial responses to allogenic forcing over both shorter 102 103 years and longer 104 106 years time scales than has commonly been the case to date as well as in larger river systems from source to sink studies of quaternary systems in depositional basin settings are especially critical because they can provide realistic analogues for interpretation of the pre quaternary rock record

holocene environmental changes and cultural patterns in coastal western india a geoarchaeological perspective abstract geomorphological studies carried out around coastal sites at hazira kanmer padri and sanjan in gujarat and chaul and kelshi in maharashtra indicate human activity throughout the holocene the offshore site at hazira of early holocene age is the only submerged prehistoric site at a depth of 20 40 m below the present sea level in the entire 7000 km long coastline of india protohistoric harappan sites at kanmer and padri are of mid holocene age the sites of sanjan chaul and kelshi represent an early historic cultural phase belonging to the late holocene age the site of hazira was located on the banks of a buried channel adjusted to the low sea level phase of the early holocene cultural development of the harappan site at kanmer in the present semi arid rocky landscape of kachchh was closely related to the existence of 2 5 m deep water in the presently dried up part of rann of kachchh throughout the mid holocene on the other hand the economy of the harappan site of padri depended on salt manufacturing in a stable estuarine environment close to the present sea level of the gulf of cambay sanjan chaul and kelshi appear to have depended on a trading economy these sites are situated in estuarine environments involving lateral transgressive regressive phases more or less within the present intertidal zone of arabian sea in a humid environment

on postglacial sea level summary an exact method is presented for calculating the changes in sea level that occur when ice and water masses are rearranged on the surface of elastic and viscoelastic non rotating earth models the method is used to calculate the instantaneous elastic and delayed vi scoelastic sea level changes following the partial melting of late quaternary ice sheets we find that there can be large errors in the usual assumption that changes in sea level are uniform over the ocean basins if a quantity of ice equivalent to a uniform 100 m rise in sea level melts from the laurentide and fennoscandian ice sheets then in the south pacific the instantaneous rise in sea level can be as large as 120m in the north atlantic the instantaneous rise is always less than 100 m there is a zone in the north atlantic with almost no sea level change and near greenland and norway the sea level falls rather than rises by over 100 m one thousand years after the melting a forebulge migrating towards the ice loads causes water to flow from the south pacific into the north pacific suggesting that raised beaches should occur in the south pacific the gravitational attraction of an ice mass upon a nearby ocean tends to hold sea level high in the vicinity of the ice this extra load near the ice may have a significant influence on postglacial isostatic adjustment

thirty years of satellite derived lava discharge rates at etna implications for steady volumetric output 1 we present a 30 year long data set of satellite derived time averaged lava discharge rates tadr for mount etna volcano sicily italy spanning 1980 2010 and comprising 1792 measurements during 23 eruptions we use this to classify eruptions on the basis of magnitude and intensity as well as the shape of the tadr time series which characterizes each effusive event we find that while 1983 1993 was characterized by less frequent but longer duration effusive eruptions at lower tadrs 2000 2010 was characterized by more frequent eruptions of shorter duration and higher tadrs however roughly the same lava volume was erupted during both of these 11 year long periods so that the volumetric output was linear over the entire 30 year period increasing at a rate of 0 8 m3 s 1 between 1980 and 2010 the cumulative volume record can be extended back in time using data available in the literature this allows us to assess etna s output history over 5 centuries and to place the current trend in historical context we find that output has been stable at this rate since 1971 at this time the output rate changed from a low discharge rate phase which had characterized the period 1759 to 1970 to a high discharge rate phase this new phase had the same output rate as the high discharge rate phase that characterized the period 1610 1669 the 1610 1669 phase ended with the most voluminous eruption of historic times

assessing the climatically triggered aggradation incision processes in a dryland environment during the late quaternary period from shetrunji river basin saurashtra india abstract the present study is an attempt to infer the response of the dryland fluvial sequences to paleoenvironmental change since the last glacial maximum lgm from the semi arid saurashtra region a basaltic terrain of the late cretaceous age deccan trap of western india we employed a conventional sedimentological analysis supported by sediment geochemistry which was constrained by optical dating based on detailed field investigation we identified five terrace sequences from the valley fill deposit in the shetrunji river basin since 18 ka i e post lgm the sedimentary archives expose the deposition during three alternate phases of aggradation and incision marked on the basis of morphostratigraphy and timing of landform evolution the coastal region of western india experienced a widespread valley aggradation in response to the rising sea stand and under gradual strengthening of the monsoonal conditions around the 18 9 ka period the early holocene climatic optima 9 7 5 ka coupled with lower than present but rising sea stand triggered the intense erosion in the valleys of shetrunji river basin leading to erosion lack of sediment preservation this was followed by the middle holocene period 7 5 5 ka which experienced valley aggradation this was ended by the incision post 5 5 ka in the lower reaches of the shetrunji river the sea stand was similar to present day stand as evidenced by the change from fluvial to the estuarine environment in the top sequence of site sl at 5 5 ka the late holocene relative sea stand lowering 3 ka led to an incision in the estuarine terrace of about 2 m the causal mechanism for triggering of this incision is most likely the relative fall in sea stand to present day level from its middle holocene high stand the late holocene period 3 1 ka shows aggradation in upper reach in fluctuating hydrodynamic conditions with seasonality followed by a relatively good monsoonal condition at

development of the 1990 kalapana flow field kilauea volcano hawaii the 1990 kalapana flow field is a complex patchwork of tube fed pahoehoe flows erupted from the kupaianaha vent at a low effusion rate approximately 3 5 m3 s these flows accumulated over an 11 month period on the coastal plain of kilauea volcano where the pre eruption slope angle was less than 2 the composite field thickened by the addition of new flows to its surface as well as by inflation of these flows and flows emplaced earlier two major flow types were identified during the development of the flow field large primary flows and smaller breakouts that extruded from inflated primary flows primary flows advanced more quickly and covered new land at a much higher rate than breakouts the cumulative area covered by breakouts exceeded that of primary flows although breakouts frequently covered areas already buried by recent flows lava tubes established within primary flows were longer lived than those formed within breakouts and were often reoccupied by lava after a brief hiatus in supply tubes within breakouts were never reoccupied once the supply was interrupted during intervals of steady supply from the vent the daily areal coverage by lava in kalapana was constant whereas the forward advance of the flows was sporadic this implies that planimetric area rather than flow length provides the best indicator of effusion rate for pahoehoe flow fields that form on lowangle slopes

regional tectonic framework structure and evolution of the western marginal basins of india abstract the kutch saurashtra cambay and narmada basins are pericontinental rift basins in the western margin of the indian craton these basins were formed by rifting along precambrian tectonic trends interplay of three major precambrian tectonic trends of western india dharwar nnw sse aravalli delhi ne sw and satpura ene wsw controlled the tectonic style of the basins the geological history of the basins indicates that these basins were formed by sequential reactivation of primordial faults the kutch basin opened up first in the early jurassic rifting was initiated in late triassic along the delhi trend followed by the cambay basin in the early cretaceous along the dharwar trend and the narmada basin in late cretaceous time along the satpura trend the evolution of the basins took place in four stages these stages are synchronous with the important events in the evolution of the indian sub continent its breakup from gondwanaland in the late triassic early jurassic its northward drifting during the jurassic cretaceous and collision with the asian continent in the early tertiary the most important tectonic events occurred in late cretaceous time the present style of the continental margins of india evolved during early tertiary time the saurashtra arch the extension of the aravalli range across the western continental shelf subsided along the eastern margin fault of the cambay basin during the early cretaceous it formed an extensive depositional platform continuous with the kutch shelf for the accumulation of thick deltaic sediments a part of the saurashtra arch was uplifted as a horst during the main tectonic phase in the late cretaceous the present high thermal regime of the cambay bombay high region is suggestive of a renewed rifting phase

mitigation of lava flow invasion hazard through optimized barrier configuration aided by numerical simulation the case of the 2001 etna eruption abstract lava flow spreading along the flanks of etna volcano often produces damages to the land and proprieties the impact of these eruptions could be mitigated by building artificial barriers for controlling and slowing down the lava as recently experienced in 1983 1991 1993 2001 and 2002 this study investigates how numerical simulations can be adopted for evaluating the effectiveness of barrier construction and for optimizing their geometry considering as test case the lava flows emplaced on etna s south flank during 2001 the flow temporal evolutions were reconstructed deriving the effusion rate trends together with the pre eruption topography were adopted as input data of the magflow simulation code three simulations were then conducted to simulate lava flow with and without barriers the first aimed at verifying the reconstruction of the effusion rate trends while the others at assessing the performance of the barrier system realized during the eruption in comparison with an alternative solution here proposed a quantitative analysis carried out on the first simulation confirms the suitability of the selected test case the comparison of the three simulated thickness distributions showed both the effectiveness of the barriers in slowing down the lava flow and the sensitivity of the magflow code to the topographical variations represented by the barriers finally for reducing both the time necessary to erect the barrier and the barrier environmental impact the gabion s barrier construction was analyzed the implemented and tested procedure enforces the capability of using numerical simulations for designing optimized lava flow barriers aimed at making swifter mitigatory actions upon lava flows and improving the effectiveness of civil protection interventions during emergencies

morphological structural and textural variations in the 1988 1990 andesite lava of lonquimay volcano chile the 1988 1990 eruption of lonquimay volcano chile 38 s formed a 10 2 km long andesite lava with a volume of 0 23 km 3 over a period of 13 months the lava extrusion rate decreased with time as chamber pressure and vent dimensions decreased the velocity of the flow front decreased exponentially with distance from vent as a consequence of cooling and the increase of apparent viscosity at the flow front the lava developed a central channel which decreased in width and depth with time three prominent lava levees were formed on each margin and resulted from abandonment as the channel decreased in width as a result of a rapid decrease of flow rate over the first 100 days of activity a fourth major levee developed in february during a brief period of flow rate increase down the main channel but its walls were gradually exposed as the lava depth again decreased due to declining flow rate the structure of lava levees depended on their age and longevity of the flow in the adjacent channel initial levees were formed in the first few days as the lava spread laterally and then retreated leaving levees of massive lava more mature rubble levees were formed during the next month by the lava pushing and then shearing aa and blocky breccia which formed on the cooling flow margin fragmentation and abrasion formed a characteristic zonation in the levees a basal zone consists of very poorly sorted matrix rich breccia with very rounded vesicular clasts and bimodal grain size distribution the basal breccia zone strongly resembles block and ash flow deposits this zone passes up into a zone of clast supported clinker breccia which becomes increasingly matrix poor and coarser with clasts becoming more angular upwards the crest of the levee is composed of large 10 100 cm angular to subangular blocks with no matrix the zoned levees form after the active lava channel suddenly narrows lava depth initially increases and breccias are deposited on the channel margins and acquire the zoned structure by progressive shearing and accretion of clinkery aa breccia the lava level then drops exposing the steep inner scarp of a levee the most mature levee type formed in a long lived channel over several months the outer wall of the levee consists of zoned breccia but the inner wall consists of a massive curving wall of strongly foliated lava with well developed horizontal striations and ductile reidel shears the massive foliated facies is a consequence of prolonged flow which coats strongly sheared lava onto the inner levee wall scanning electron microscopy shows that the aa clinker clasts and foliated lava from the levee walls form at low melt fractions 15 in the last three months of the eruption the flow front ceased to advance but thickened as lava drained from proximal regions and intruded into the interior of the distal lava the last stages of lava movement were characterized by updoming in the central channel a lava surface feature named here armadillo structure was formed by deformation of the cooler but still ductile lava crust the deformation caused by underflow produced reidel shears dipping upstream and doming of the lava due to rotation of the shear planes the study demonstrates that lava morphology structure and texture are strongly influenced by variations of effusion rate local flow rate channel topography and thermal maturity of the lava which is reflected in downstream changes in viscosity

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

interpreting the response of a dryland river system to late quaternary climate change abstract a u series calcrete chronology has been constructed for three late quaternary terrace units termed the d1 d2 and d3 terraces in age descending order from the rio aguas river system of the sorbas basin southeast spain the d1 terrace formed between 30 300 4400 year bp and 12 140 360 year bp correlating well with the last glacial maximum when rates of sediment supply would have increased greatly because of higher rates of weathering reduced vegetation cover and weak soil development the d2 terrace formed between 12 800 1100 year bp and 9 600 530 year bp correlating well with the younger dryas event the d3 terrace could only be poorly constrained to the early holocene and no unequivocal cause could be assigned to this period of aggradation the sedimentology and geomorphology of the d2 terrace suggests however that the aggradation of this unit was a response to diapirism karstic processes occurring within the underlying messinian gypsum strata and the subsequent damming of the aguas system therefore despite its coincident occurrence with the younger dryas aggradation of the d2 terrace is unrelated to climate change the style of this response controlled predominantly by the characteristics of the underlying bedrock makes correlating the terrace record of the aguas with other systems in the mediterranean unreliable this study therefore highlights the problems of correlating fluvial sequences in regions of variable tectonics climatic history and bedrock geology and emphasises the need to properly understand the main controls on individual fluvial systems before any attempt is made to correlate their depositional histories

reconstruction of late quaternary monsoon oscillations based on clay mineral proxies using sediment cores from the western margin of india abstract in order to reconstruct the variations in the intensity of summer monsoon precipitation during the late quaternary two sediment cores from the southwestern continental margin of india were studied for their clay mineral composition and grain size parameters kaolinite illite and gibbsite were dominant in a core off cochin illite with increasing kaolinite content towards the core top was found to dominate in a core from the continental slope off goa major sources of clays at both the core sites were from the hinterland rocks and soils careful evaluations of several factors that could complicate the clay distribution in marine environment indicate that the clay mineral parameters can be used as proxies for the intensity of summer monsoon precipitation in the past the relatively low values of humidity proxies kaolinite content k c and k i ratios and higher illite crystallinity with significant variations indicate that the summer monsoons in general were weaker during the late glaciation with distinct events of intensification at 28 000 and 22 000 yr bp the last deglaciation was characterised by an increased terrigenous input with high values of humidity proxies during 15 700 14 800 cal yr bp indicating an early strengthening of summer monsoon activity in the region the most remarkable increase in kaolinite content k c and k i ratios associated with much reduced values of chlorite and illite and illite crystallinity however occur between 8800 and 6400 cal yr bp it appears that the holocene precipitation maxima occurred after 9000 cal yr bp and lagged behind the precessional forcing the late holocene witnessed reduced rainfall activity and resultant decrease in hydrolysis starting at 5600 cal yr bp