spatial variability of hydraulic conductivity and bulk density along a blanket peatland hillslope this article presents the results of a field investigation of saturated hydraulic conductivity ksat and bulk density bd in an atlantic blanket bog in the southwest of ireland starting at a peatland stream and moving along an uphill transect toward the peatland interior bd and ksat were examined at regular intervals saturated horizontal hydraulic conductivity khsat and vertical kvsat was estimated at two depths 10 20 and 30 40 cm below the peat surface whereas bd was estimated for the full profile we consider two separate zones one a riparian zone extending 10 m from the stream and a second zone in the bog interior we found that the ksat was higher 10 5 m s 1 in the bog interior than that in the riparian zone 10 6 m s 1 whereas the converse applied to bulk density with lowest density 0 055 g cm 3 at the interior and highest 0 11 g cm 3 at the riparian zone in general we found khsat to be approximately twice the kvsat these results support the idea that the lower ksat at the margins control the hydrology of blanket peatlands it is therefore important that the spatial variation of these two key properties be accommodated in hydrological models if the correct rainfall runoff characteristics are to be correctly modelled stream flow analysis over 3 years at the peatland catchment outlet showed that the stream runoff was composed of 8 base flow and 92 flood flow suggesting that this blanket peatland is a source rather than a sink for floodwaters copyright 2011 john wiley sons ltd

macroporosity and infiltration in blanket peat the implications of tension disc infiltrometer measurements little is known about the processes of infiltration and water movement in the upper layers of blanket peat a tension infiltrometer was used to measure hydraulic conductivity in a blanket peat in the north pennines england measurements were taken from the surface down to 20 cm in depth for peat under four different vegetation covers it was found that macropore flow is a significant pathway for water in the upper layers of this soil type it was also found that peat depth and surface vegetation cover were associated with macroporosity and saturated hydraulic conductivity the proportion of macropore flow was found to be greater at 5 cm depth than at 0 10 and 20 cm depth peat beneath a sphagnum cover tends to be more permeable and a greater proportion of macropore flow can occur beneath this vegetation type functional macroporosity and matrix flow in the near surface layers of bare peat appear to have been affected by weathering processes comparision of results with rainfall records demonstrates that infiltration excess overland flow is unlikely to be a common runoff generating mechanism on blanket peat rather a saturation excess mechanism combined with percolation excess above much less permeable layers dominates the runoff response copyright 2001 john wiley sons ltd

timing kinematics and cause of aegean extension a scenario based on a comparison with simple analogue experiments abstract since the early 1970s most geodynamic models proposed for the eastern mediterranean consider that the initiation of extension in the aegean during the late middle miocene or later was a direct consequence of the westward extrusion of anatolia away from the arabia eurasia collision front in the late 1990s a few models have taken into account the increasing evidence for an earlier initiation of aegean extension arising mostly from the analysis of deformation within the various alpine metamorphic complexes of the area based largely on our own investigations we first present a review of the data that reliably constrain the minimum age for the initiation of extension in these complexes it shows that regional scale extension with a pattern of stretching orientations similar to that of the pliocene pleistocene was already strongly active in the aegean before the onset of arabian indentation into eurasia lower miocene vs middle or upper miocene this implies that the initiation of aegean extension did not result from the lateral extrusion of anatolia instead extension may have started owing to a process of gravity spreading of the continental lithosphere that had previously been thickened during alpine collision the main arguments favouring this interpretation are presented and a preliminary scenario is proposed for the neogene evolution of the eastern mediterranean in which lateral extrusion of anatolia occurred lately during southward spreading of the aegean lithosphere in order to test this hypothesis further physical experiments simulating the horizontal spreading of a continental lithosphere toward a free boundary have been carried out the analysis of various elements of the deformation field displacements strain rotations fault pattern and kinematics both in the experiments and in the aegean domain reveals an excellent agreement between the two not only do early stages of aegean extension appear to fit the gravity spreading hypothesis but so does the recent to present internal deformation of the aegean transverse e w active shortening observed in the northern aegean is commonly taken as one of the most striking pieces of evidence that aegean extension results from the lateral extrusion of anatolia the experiments indicate that such transverse shortening may equally develop as a result of pure gravity spreading associated with a pattern of faults and rotations that compares well with that of the northern aegean pure dextral shearing along some strands of the north aegean trough fault system and the related development of an asymmetric pattern of faults in the northern aegean are eventually the only features that evidently arise from the extrusion of anatolia since less than 3 ma finally we argue that during the early stages of aegean extension since at least 21 ma and until ca 11 ma the distribution of extensional strain on a regional scale has been controlled by the distribution of earlier thickening post thickening thermal weakening through partial melting of deep levels of the crust probably accounts for the localization of extensional strain within the areas of thick crust restoring the aegean in its most likely configuration at the onset of bulk crustal extension suggests that 1 the extensional strain rate remained roughly constant or has eventually decreased since the onset of aegean extension and 2 the amounts of extension before and after 16 ma have been roughly equal

morphology structure and flow phases in soil pipes developing in forested hillslopes underlain by a quaternary sand gravel formation hokkaido northern main island in japan preferential flow pathways such as soil pipes are usually present in the soil of slopes subsurface flow through the soil pipes affects the subsurface drainage system and is responsible for sediment removal from slopes however a record of the inner structure of soil pipes has rarely been reported for slopes a fibrescope examination of the morphology and flow phases in soil pipes in hillslopes underlain by a quaternary sand gravel formation provided the following information the main pores of the soil pipes ran mostly parallel with the slope gradient the cross sections of the soil pipes were approximately circular and occurred on a few occasions with some triple junctions being present in addition both full flow and partly full depth conditions occurred simultaneously in the soil pipe the full flow condition has long been used in hydrological studies to model the pipe flow mechanism both the full flow condition and the partly full depth condition however must be examined closely in order to evaluate the subsurface hydrology in heterogeneous soil and the hydrogeomorphological processes of subsurface hydraulic erosion copyright 2000 john wiley sons ltd

continental crust composition constrained by measurements of crustal poisson s ratio deciphering the geological evolution of the earth s continental crust requires knowledge of its bulk composition and global variability the main uncertainties are associated with the composition of the lower crust seismic measurements probe the elastic properties of the crust at depth from which composition can be inferred of particular note is poisson s ratio this elastic parameter can be determined uniquely from the ratio of p to s wave seismic velocity and provides a better diagnostic of crustal composition than either p or s wave velocity alone1 previous attempts to measure have been limited by difficulties in obtaining coincident p and s wave data sampling the entire crust2 here we report 76 new estimates of crustal spanning all of the continents except antarctica we find that on average increases with the age of the crust our results strongly support the presence of a mafic lower crust beneath cratons and suggest either a uniformitarian craton formation process involving delamination of the lower crust during continental collisions followed by magmatic underplating or a model in which crust formation processes have changed since the precambrian era

core complex geometries and regional scale flow in the lower crust a simple flexural model that treats the lithosphere as a thin elastic plate overlying a fluid asthenosphere produces an excellent fit to the domal detachment fault geometries observed in typical core complexes of the basin and range province however this mode of isostatic compensation requires an unacceptably large reduction in local topographic elevation 3 5 km above core complex structures because topographic lows of this magnitude are not observed above core complexes today it requires mountain ranges 3 5 km higher than the surrounding areas to have existed at the site of each future core complex and requires these mountain ranges to have had large crustal roots that were subsequently uplifted to form a flat moho as the core complexes developed an alternate mode of isostatic compensation whereby compensation occurs primarily by regional scale flow of material within the lower crust beneath an elastic midcrust provides an equally good fit to the observed detachment fault geometries while requiring little reduction in local topographic elevation above developing core complex structures and providing an obvious means of maintaining a flat moho beneath these zones of upper crustal doming if this interpretation is correct then the effective elastic plate thickness below the basin and range province probably cannot exceed a maximum of about 4 km with a best guess estimate of about 0 5 to 1 km computation of the temperature structure associated with crustal flow during doming shows that an increase in temperature at the moho of about 100 c follows doming by several million years perhaps explaining the observed coincidence of core complexes with crustally derived igneous rocks subsequent cooling of the mid to lower crust beneath the core complex could result in freezing of the initially ductile lower crust within the core of the dome effectively locking the domal shape into the crust even after the detachment surface is cut by younger faults

impact of soil characteristics and land use on pipe erosion in a temperate humid climate field studies in belgium abstract this study investigates the role of soil characteristics and land use in the development of soil pipes in the loess belt of belgium first we tested the hypothesis that discontinuities in the soil profile enhance lateral flow and piping by impeding vertical infiltration we focus on discontinuities in soil characteristics that can vary with soil depth including texture saturated hydraulic conductivity penetration resistance and bulk density these characteristics as well as soil biological activity were studied in detail on 12 representative soil profiles for different land use types twelve sites were selected in the flemish ardennes belgium four pastures with collapsed pipes cp four pastures without cp two sites under arable land without cp and two sites under forest without cp secondly this study aimed at evaluating the interaction of groundwater table positions through soil augerings and cp in a larger area with a focus on pastures pasture is the land use where almost all cp in the study area are observed therefore the position of the groundwater table was compared for 15 pastures with cp and 14 pastures without cp having comparable topographical characteristics in terms of slope gradient and contributing area finally the effect of land use history on the occurrence of pipe collapse was evaluated for a database of 84 parcels with cp and 84 parcels without cp currently under pasture as to the first hypothesis no clear discontinuities for abiotic soil characteristics in soil profiles were observed at the depth where pipes occur but pastures with cp had significantly more earthworm channels and mole burrows at larger depths 120 cm mean of 200 earthworm channels per m 2 than pastures without cp arable land or forest 120 cm depth a few or no earthworm channels left the land use history appeared to be similar for the pastures with and without cp combining all results from soil profiles and soil augering indicates that intense biological activity especially by earthworms and moles in combination with a sufficiently high groundwater table favours the development of soil pipes in the study area

tectonics and magmatism in turkey and the surrounding area this volume contains 23 papers from a range of international contributors describing recent research into the tectonics and magmatism of turkey and its surroundings this region is sited at the collision zone between eurasia and afro arabia and as such provides an extraordinarily complete and well exposed record of the staged tectonic evolution of this sector of the alpine himalayan orogen the geological history of this area involves separation of continental fragments from the margin of gondwana their migration across the tethyan oceans the subsequent closure of these oceans and finally the development of the neotectonic regime which continues to evolve to the present day such a comprehensive record is relevant to the understanding of collisional zones worldwide the volume is divided into five sections tethyan evolution neotethyan ophiolites post tethyan basin evolution neotectonics and igneous activity the first two sections deal with tethyan oceans whose growth and subsequent closure dominated the geodynamic framework in the mesozoic and cenozoic the subsequent sections deal with more recent geological developments from the balkan peninsula in the west to the transcaucasus in the east that followed consumption of the tethyan oceans there is a broad mix of papers throughout the volume wide ranging review papers on ocean development and extensional tectonics are followed by detailed descriptions of petrology and geochemistry and geographically focused studies on basin evolution specific aspects of extensional and strike slip tectonics and discussions of the relationship of magmatic activity to the tectonic development of the area tectonics and magmatism in turkey and the surrounding area presents up to date results and ideas from a large number of international contributors on a wide range of current research activity in this region it is essential reading for all geoscientists with an interest in both academic and applied aspects of eastern mediterranean geology

hydrogeological characterization of an altered wetland summary spatiotemporal changes in the hydrogeology of the hula altered wetland may influence the water quality of lake kinneret which provides up to 30 of the potable water for the state of israel the main objectives of this work were to study the groundwater flow characteristics in this wetland and assess the potential impact on downstream water quality we constructed variograms of hydraulic heads computed decision tree models of major ions and determined the hydraulic conductivity k and 2 h 18 o ratios to ascertain the spatial and vertical distribution of hydrogeological parameters we also performed large scale field experiments 1 km 2 to assess the connectivity between the waterways and the wetland s aquifer the aquifer is fragmented by three parent materials deep peat shallow peat marl complex and marl the decision tree based model the isotopic ratios and k determinations suggest that the deep peat subaquifer is composed of one homogeneous layer characterized by low k 0 001 m d 1 the two other subaquifers consist of three hydrostratigraphic layers i the vadose zone ii a layer with well developed macropores at a depth of 1 5 4 m and iii an aquitard layer at a depth of 4 15 m the temporal head fluctuations the high k values of the second layer 170 m d 1 and the large volume of water flowing into and out of the two subaquifers during large scale field experiments all attest to excellent connectivity with the waterways these results support the concept of critical source area which claims that most of the p loss in a catchment derives from small areas in which specific p release and transport mechanisms coincide with high connectivity we conclude that the high connectivity of this mediterranean altered wetland to waterways coupled with the high p release that has occurred in recent years following soil flooding provides the loading mechanism that partially explains the observed p increase in the jordan river

aegean crustal thickness inferred from gravity inversion geodynamical implications since oligo miocene times the aegean domain has undergone regional extension due to the southward retreat of the hellenic subduction zone boundary conditions have been more recently modified by the westward extrusion of anatolia a new map of the aegean crustal thickness inferred from gravity inversion is proposed here to better constrain the variations in space and time of crustal thinning that has accumulated since oligo miocene times moho topography is obtained by inversion of satellite marine gravity data data are first corrected for terrain anomalies and deep mantle effects african subducting slab they are then filtered between 50 and 300 km to avoid short wavelength intracrustal effects results are consistent with previous 2d geophysical studies seismic refraction receiver functions and show that an overall regional isostatic compensation of the crust holds for the aegean area with a mean crustal thickness of 25 km three different provinces north aegean cyclades and cretan sea can be identified thinner crust is observed both in the north aegean region ne sw trending of thinning with crustal thickness lower than 24 km and in the cretan sea crustal thickness of 22 23 km between these two regions the cyclades are marked by a rather flat moho at 25 km a two stage model of the aegean extension could well explain the observed crustal thickness variation from oligocene to middle miocene gravitational collapse of the hellenides due to the southward retreat of the african slab reduced the aegean continental crust from 50 km by reference to continental greece and anatolia to a mean value of 25 km at the scale of the whole aegean from upper miocene to present the westward extrusion of anatolia modified the extension and the associated crustal thinning in the north aegean domain during this second episode crustal thinning related to the southward retreat of the african slab tends to localize in the cretan sea the cyclades likely behave as a rigid block translated toward the south west without significant deformation in agreement with the gps velocity field and the lack of major earthquakes d 2004 elsevier b v all rights reserved

exhumation of high pressure rocks driven by slab rollback rocks metamorphosed under high pressure hp and ultra high pressure uhp conditions in subduction zones come back to the surface relatively soon after their burial and at rates comparable to plate boundary velocities in the mediterranean realm their occurrence in several belts related to a single subduction event shows that the burial exhumation cycle is a recurrent transient process using the calabria apennine and aegean belts as examples we show that the exhumation of hp rocks is associated in time and space with the subduction of small continental lithosphere blocks that triggers slab rollback creating the necessary space for the exhumation of the buoyant continental crust that was deeply buried just before the buoyancy force of the subducted crust increases until this crust detaches from the downgoing slab it then exhumes at a rate that depends directly on the velocity of trench retreat to become part of the overriding plate heated from below by the asthenosphere that flows into the opening mantle wedge the exhumed crust weakens and undergoes core complex type extension responsible for a second stage of exhumation at a lower rate the full sequence of events that characterizes this model crust mantle delamination slab rollback and trench retreat hp rock exhumation asthenosphere heating and core complex formation arises entirely from the initial condition imposed by the subduction of a small continental block no specific condition is required regarding the rheology and erosion rate of hp rocks the burial exhumation cycle is transient and can recur every time a small continental block is subducted

the active main marmara fault abstract this paper presents selections from and a synthesis of a high resolution bathymetric sparker and deep towed seismic reflection data set recently acquired by the french ifremer r v le suroit in an e w deep trough that forms the northern half of the sea of marmara in nw turkey it includes the first high resolution complete bathymetric map of this area a single throughgoing dextral strike slip fault system which is the western continuation of the northern branch of the north anatolian fault cuts this trough lengthwise and joins the 1999 8 17 kocaeli earthquake fault with the 1912 8 09 arkoy murefte earthquake fault both of which display strike slip offset in its eastern one fourth the structure follows closely the northern margin of the deep trough whereas in the west it hugs its southern margin the eastern one fourth of the structure has a minor component of its displacement distributed across the deep trough owing to a possible original bend in the course of the dextral structure the present course of the north anatolian fault in the sea of marmara originated some 2 105 a ago by cutting across the older basin fabric generated by a dominant nne ssw extension before it began taking up major motion in the pliocene

aegean tectonics strain localisation slab tearing and trench retreat abstract we review the geodynamic evolution of the aegean anatolia region and discuss strain localisation there over geological times from late eocene to present crustal deformation in the aegean backarc has localised progressively during slab retreat extension started with the formation of the rhodope metamorphic core complex eocene and migrated to the cyclades and the northern menderes massif oligocene and miocene accommodated by crustal scale detachments and a first series of core complexes mccs extension then localised in western turkey the corinth rift and the external hellenic arc after messinian times while the north anatolian fault penetrated the aegean sea through time the direction and style of extension have not changed significantly except in terms of localisation the contributions of progressive slab retreat and tearing basal drag extrusion tectonics and tectonic inheritance are discussed and we favour a model 1 where slab retreat is the main driving engine 2 successive slab tearing episodes are the main causes of this stepwise strain localisation and 3 the inherited heterogeneity of the crust is a major factor for localising detachments the continental crust has an inherited strong heterogeneity and crustal scale contacts such as major thrust planes act as weak zones or as zones of contrast of resistance and viscosity that can localise later deformation the dynamics of slabs at depth and the asthenospheric flow due to slab retreat also have influence strain localisation in the upper plate successive slab ruptures from the middle miocene to the late miocene have isolated a narrow strip of lithosphere still attached to the african lithosphere below crete the formation of the north anatolian fault is partly a consequence of this evolution the extrusion of anatolia and the aegean extension are partly driven from below asthenospheric flow and from above extrusion of a lid of rigid crust

factors controlling the distribution of piping in britain a reconnaissance abstract the distribution of piping in britain has been studied from a survey of 74 piped basins and a number of in depth studies at the individual basin scale the survey suggests that nearly 30 of britain is susceptible to piping erosion this is the area covered by soils with histic and vertic properties or with impermeable subsoil horizons lying in upland regions with high annual water balance and steep slopes at an intrabasin scale the intensity of piping shows a broad correspondence with the a s drainage index although there is no fixed relationship and some significant deviations are found inhomogeneities in soil properties and differential exposure to cracking may be the main cause landuse and vegetation cover may also affect distributions however the clearest intrabasin links between pipe distribution and vegetation patterns are found in upland moorland where the pipes are the cause rather than the product of patterns in both soils and vegetation

variations in the crustal structure beneath western turkey summary we use teleseismic receiver functions to investigate the crustal structure at two locations in westernturkey using seismic data recorded on small arrays of temporary broad band seismographs the results from these analyses are compared with receiver function results from the gdsn station anto on the anatolian plateau in central turkey the crust is 30 km thick in the region of western turkey where active normal faulting reveals present day extension in the upper crust and alkali basaltic volcanism reveals recent extension within the subcrustal lithosphere the crust is 34 km thick further east where crustal extension is still evident but less pronounced in the anatolian plateau which is not currently extending the crust is 38 km thick the level of extension estimated from these measurements of crustal thickness implies a b factor of 1 2 this value agrees with the amount of extension estimated in the upper crust from the integrated seismic strain rate b factor of 1 3 from surface faulting b factor of 1 25 and from the amount of extension in the subcrustal lithosphere estimated from the volcanism b factor 2 all indicating that the extension is approximately uniformly distributed vertically throughout the lithosphere the moho transition in this region appears to thin slightly as the degree of extension increases westwards

controls of soil pipe frequency in upland blanket peat 1 soil pipes were surveyed in 160 british blanket peat catchments using consistent application of ground penetrating radar soil pipes were found in all catchments the mean frequency of piping was 69 per kilometer of surveyed transect land management moorland gripping appears to exert the most important control on hillslope pipe frequency in blanket peats management practice in peatlands may therefore induce more rapid subsurface erosion carbon loss and landform denudation via enhanced preferential flow topographic position is also important with topslopes having greater pipe frequencies than footslopes followed by midslopes with lowest frequencies slope gradient however is not a significant factor in controlling blanket peat pipe frequency i propose that peat structural properties inherited from the way a blanket peat develops on a hillslope strongly control pipe network development this is manifested in the way slope position appears to control pipe frequency aspect appears not to influence pipe frequency in blanket peats except that it does play a weak role in catchments with annual precipitation 1500 mm here southwesterly facing slopes tend to have more frequent piping

topographic controls upon soil macropore flow macropores are important components of soil hydrology the spatial distribution of macropore flow as a proportion of saturated hydraulic conductivity was tested on six humid temperate slopes using transects of tension infiltrometer measurements automated water table and overland flow monitoring allowed the timing of and differentiation between saturation excess overland flow and infiltration excess overland flow occurrence on the slopes to be determined and related to tension infiltrometer measurements two slopes were covered with blanket peat two with stagnohumic gleys and two with brown earth soils none of the slopes had been disturbed by agricultural activity within the last 20 years this controlled the potential for tillage impacts on macropores the proportion of near surface macropore flow to saturated hydraulic conductivity was found to vary according to slope position the spatial patterns were not the same for all hillslopes on the four non peat slopes there was a relationship between locations of overland flow occurrence and reduced macroporosity this relationship did not exist for the peat slopes investigated because they experienced overland flow across their whole slope surfaces nevertheless they still had a distinctive spatial pattern of macropore flow according to slope position for the other soils tested parts of slopes that were susceptible to saturation excess overland flow e g hilltoes or flat hilltops tended to have least macropore flow to a lesser extent for the parts of slopes susceptible to infiltration excess overland flow the proportion of macropore flow as a component of infiltration was also smaller compared with the rest of the slope the roles of macropore creation and macropore infilling by sheet wash are discussed and it is noted that the combination of these may result in distinctive topographically controlled spatial patterns of macropore flow copyright 2008 john wiley sons ltd

the impact of pipe flow in riparian peat deposits on nitrate transport and removal the effect of preferential flow in soil pipes on nitrate retention in riparian zones is poorly understood the characteristics of soil pipes and their influence on patterns of groundwater transport and nitrate dynamics were studied along four transects in a 1 to 3 m deep layer of peat and marl overlying an oxic sand aquifer in a riparian zone in southern ontario canada the peat marl deposit which consisted of several horizontal layers with large differences in bulk density contained soil pipes that were generally 0 1 to 0 2 m in diameter and often extended vertically for 1 to 2 m springs that produced overland flow across the riparian area occurred at some sites where pipes extended to the peat surface concentrations of no3 n 20 30 mg l 1 and dissolved oxygen do 4 6 mg l 1 observed in peat pipe systems and surface springs were similar to values in the underlying sand aquifer indicating that preferential flow transported groundwater with limited nitrate depletion low no3 n concentrations of 15 mg l 1 extended over a larger zone low dissolved organic carbon values at these locations suggest that supplies of organic carbon were not sufficient to support high rates of denitrification despite low do conditions these data indicate that it is important to develop a greater understanding of pipes in peat deposits which function as sites where the transport of large fluxes of water with low biogeochemical reaction rates can limit the nitrate removal capacity of riparian zones copyright 2011 john wiley sons ltd

long wavelength undulations of the seismic moho beneath the strongly stretched western anatolia summary western turkey provides spectacular examples of the two end member models of deformation of the continental lithosphere with strain localization along the north anatolian fault and distributed north south extension along the aegean coast to provide constraints on the mechanisms of continental deformation we present a new high resolution image of lithospheric structurealonga 650kmtransectcrossingwesternanatoliaat28 elongitudefromtheblack sea to the mediterranean more than 2600 receiver functions are computed from records of teleseismic earthquakes at 40 broadband seismic stations with an average spacing of 15km lateral variations of crustal thickness and vp vs ratio are inferred from both h k and common conversion point stacks we observe long wavelength variations of moho depth from 31km in the thrace basin to 25km beneath the marmara sea 32km beneath the izmir ankara suture 25km beneath the menderes massif and 20km on the coast of the mediterranean no mid or lower crustal interface is visible in the migrated depth section and seismic discontinuities are confined to the shallow crust the small amplitude and long wavelength lateral variations of the moho topography suggest that viscous flow in a hot lower crust has smoothed out the lateral variations of crustal thickness induced by cenozoic continent continent collision thecrust mantleboundaryisflatbeneaththecentralandsouthernmenderesmassif the rougher moho topography and more heterogeneous crust of the marmara region likely result from transtension in the north anatolian fault zone superimposed onto aegean extension the moho of the subducted african lithosphere is observed dipping northward between 40 and 60km depth at the southern end of the profile the abrupt termination of the subducted slab only 50km to the north of the mediterranean coast confirms the slab tear inferred from previous tomographic studies

erosion and natural revegetation associated with surface land drains in upland peatlands open cut drains are the most frequently used drainage technique in peatlands and are common throughout the world land drains increase the drainage density and promote enhanced coupling of hillslope sediment sources with streams they may be major sources of fine sediment to peatland stream systems but data on drain sediment production in peatlands are rare many drains are now being dammed by humans yet some revegetate naturally this paper presents a survey of the erosion and natural revegetation of peat drains related to variables such as slope drainage area and shading the paper also provides measured comparison of sediment flux from open drains drains that have been blocked by peat dams undisturbed subcatchments and the catchment outlet natural infilling of drains was often found to occur on gentle slopes 4 were rarely infilled nick point retreat at the confluence of drains was often observed revegetation of drains was uncommon where drains have been cut or incised into the underlying mineral substrate where the drain floor was peat based revegetation was much more common revegetation of drain floors was affected by overhanging vegetation which provided shading drain floors with less than 60 shading tended to have a greater vegetation cover than drains with 60 90 shading however drains that were almost totally shaded 90 had the greatest floor vegetation the intact drains were found to be major sources of suspended sediment within the survey catchments with 18 3 of the sediment originating from the unblocked drains which drained 7 3 of the area the winter quarter of the year was more important than other seasons for producing suspended sediment even though precipitation totals were not greatest during this period drains which had been dammed at intervals along their length using peat blocks had very low sediment yields even poorly dammed drains where water could still flow along the full course of the drain had 54 times less suspended sediment production than unblocked drains copyright 2007 john wiley sons ltd

generating multi proxy holocene palaeoenvironmental records from blanket peatlands abstract ombrotrophic peatlands have provided important archives for understanding holocene palaeoenvironmental change however records are predominantly from raised bogs due to potential issues regarding preservation of proxy indicators record length and low temporal resolution in other peat types including blanket bogs by carrying out peat depth and stratigraphy surveys we demonstrate how blanket peatlands can provide archives capable of providing records that are not reliant on single proxies as has been often the case in the past and can provide good resolution records a record containing humification testate amoebae and plant macrofossils was derived for the last 3000 years with accumulation rates as high as 8 yrs cm 1 providing favourable temporal resolution particularly over the last 1500 years major changes in proxy indicators reflecting potential changes in water table depth were often coherent with changes in climate human activity also had a major impact on the peatland throughout the record especially in the last 100 years where the influence of wildfire and managed burning together with an effect of atmospheric pollution fundamentally changed the state of the peatland

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

a fore arc origin for the thrace basin nw turkey hydrocarbon bearing thrace basin occupies much of the european part of turkey the middle eocene to oligocene sequence in the centre of the basin exceeds 9 km in thickness based on the stratigraphy structure and the regional context of this basin we propose that it developed as a fore arc basin between the medial eocene and the oligocene above the northward subducting intra pontide ocean its post miocene history has been dominated mainly by wrench tectonics resulting from the activity of the now deactivated northwestern strand of the present day north anatolian fault zone

menderes massif western turkey structural metamorphic and magmatic evolution a synthesis the menderes massif covers large areas in western turkey the better understanding of its tectono metamorphic history would provide insight for the alpine evolution of western turkey and the entire eastern mediterranean region this paper summarizes the available literature on the metamorphic rocks of western turkey and that of the menderes massif with special reference and emphasis to the papers presented in the special issue

tunnel erosion and sediment production in the hilly loess region north china in this study detailed monitoring of water and sediment delivery from major tunnel systems was conducted in a small semi arid sub basin locally known as yangdaogou in the hilly loess region north china these deep seated tunnels are located as much as 30 m below the slope surface in deep quaternary loess formations in the yangdaogou these systems have large amphitheatre like inlets with mean diameter and depth of 4 8 and 4 99 m respectively these dimensions represent some of the largest tunnel inlets in the world during 1989 and 1990 fifteen rainstorms were monitored at six tunnel outlets due to practical difficulties only 35 sets of tunnel storm data were obtained observed sediment concentration of tunnel flows ranges from 8 2 to 893 2 g l the peak sediment concentrations in tunnel flows are not distinctively higher than those in channel flows but considerably higher than those measured from untunneled sideslopes no significant correlations between runoff and sediment yield can be found in most tunnels at both within and between storm levels such an erratic relationship is ascribed to the rapid shift of runoff and sediment source area the occurrence of collapses within tunnels and the initiation of new tunnel inlets based on the field monitored data 57 of basin sediment production is delivered by the tunnel systems suggesting that tunnel erosion is a major erosion process in the hilly loess region

soil pipe collapses in a loess pasture of goodwin creek watershed mississippi role of soil properties and past land use little is known about the association of soil pipe collapse features with soil properties or land use history three loess covered catchments in northern mississippi usa were characterized to investigate these relationships soil pipe collapses were characterized for their size type feature and spatial location along with soil properties across the three catchments although mapped as the same soil one of the catchments did not contain pipe collapse features while the other two had 29 4 and 15 4 pipe collapses per hectare these loess soils contained fragipan layers that are suspected of perching water thereby initiating the piping processes pipe collapses associated with subsurface flow paths were not always consistent with surface topography the surface layer tended to be non erodible while layers below even the upper fragipan layers were susceptible to erosion by pipeflow soil properties of the lowest fragipan layer were highly variable but tended to prevent further downward erosion of soil pipes and thus formed a lower boundary for gullies middle to lower landscape positions in one of the piped catchments contained anthropic soils that were highly erodible these anthropic soils were previously gullies that were filled in in the 1950s when forested areas assumed to have been established when land was previously converted from crop to forest land were converted to pasture three decades after this land use change from forest to pasture pipe collapses became evident in contrast the adjacent catchment that does not exhibit pipe collapse features experienced severe sheet and rill erosion prior to the 1930s while in cotton production the surface horizons above the lower fragipan layer were completely removed during this period thus the top soil layer that tends to form a bridge above soil pipes in the more erodible subsoil layers was removed this study showed that knowledge of soil characteristics or topography alone do not explain the distribution of soil pipe collapses as past land use can play a definitive role copyright 2015 john wiley sons ltd

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

sediment and particulate carbon removal by pipe erosion increase over time in blanket peatlands as a consequence of land drainage land drainage is common in peatlands artificially drained blanket peat catchments have been shown to have a significantly greater soil pipe density than intact catchments this paper investigates the role of surface land drains in the enhancement of soil piping in blanket peats the density of piping was found to significantly increase in a linear fashion with the age of the drainage thirty five years after drains were cut slopes would be expected to have twice the density of soil piping than would an undrained blanket peat catchment the rate of pipe erosion increases exponentially over time so that particulate carbon loss from subsurface pipes is greatest where drains are oldest

the role of soil pipes as a slope runoff mechanism subarctic yukon canada pipeflow in subarctic slopes provides a preferential runoff mechanism that bypasses the soil matrix rapidly conveying water to the stream extensive soil piping occurs in the central wolf creek basin yukon at the interface of the organic and mineral horizons flow in these pipes are ephemeral transmitting water only when the water table is within or above the zone where pipes occur during snowmelt pipeflow began several days after the onset of surface runoff pipeflow contribution increased until ground thaw lowered the water tables leaving matrix flow within the organic layer as the dominant mode of runoff pipeflow accounted for 21 of runoff during the 15 day melt period of 1997 following melt pipeflow recurred only during two intense summer rainstorms each yielding different pipeflow response characteristics during melt pipeflow closely followed the daily snowmelt cycles and responded earlier than the integrated slope runoff in the summer pipeflow hydrographs rose and fell much quicker than direct storm runoff from the entire slope which was dominated by fast matrix flow within the organic layer pipeflow contributing areas were relatively small but their extent changed with hillslope wetness analysis revealed that the manning flow formula can be combined with contributing areas to simulate pipeflow discharges unlike temperate environments where frozen ground is not a factor the frost table position significantly controls the position of the phreatic surface and must be considered in any models of pipeflow in permafrost slopes

westward propagation of the north anatolian fault into the northern aegean timing and kinematics we present new evidence for the propagation processes of the north anatolian fault folding in the dardanelles straits region allows us to document the timing of the deformation preceding and the finite displacement after the passage of the propagating tip of the fault the accuracy of the observations is due to interplay between deformation and the sea level changes in the mediterranean the well known messinian regression followed by the pliocene transgression the long term kinematics around the sea of marmara pull apart total displacement of about 85 km over the past 5 m y is similar to the present day kinematics deduced from space geodesy at a larger scale westward propagation of the north anatolian fault over nearly 2000 km in the past 10 m y appears to be associated with strain recovery suggesting that the continental lithosphere retains long term elasticity

hydraulic conductivity in upland blanket peat measurement and variability a key parameter used in wetland hydrological and landform development models is hydraulic conductivity head recovery tests are often used to measure hydraulic conductivity but the calculation techniques are usually confined to rigid soil theory this is despite reports demonstrating the misapplication of rigid soil theory to non rigid soils such as peats while values of hydraulic conductivity calculated using compressible techniques have been presented for fenland peats these data have never to the authors knowledge been compared to such calculations in other peat types head recovery tests slug withdrawal were performed on piezometers at depths ranging from 10 cm to 80 cm from the surface on north pennine blanket peats results were obtained using both rigid and compressible soil theories allowing comparison of the two techniques compressible soil theory gives values for hydraulic conductivity that are typically a factor of five times less than rigid soil calculations hydraulic conductivity is often assumed to decrease with depth in upland peats but at the study site in the northern pennines it was not found to vary significantly with depth within the range of peat depths sampled the variance within depth categories was not significantly different to the variance between depth categories showing that individual peat layers did not have characteristic hydraulic conductivity values thus large lateral and vertical differences in hydraulic conductivity over short distances creates problems for modelling but may help account for the high frequency of preferential flow pathways within what is otherwise a low matrix hydraulic conductivity peat hydraulic conductivity was found to vary significantly between sampling sites demonstrating that hillslope or catchment scale variability may be more important than plot scale variability values for compressibility of the peats are also reported these generally decline with depth and also vary significantly between sampling sites there are implications for the way in which measurements of hydraulic conductivity and other properties of blanket peat are interpreted as the effects of environmental change in one part of a peat catchment may be very different to those in another

prediction of spatial patterns of collapsed pipes in loess derived soils in a temperate humid climate using logistic regression abstract soil piping tunnel erosion has been recognised as an important erosion process in collapsible loess derived soils of temperate humid climates which can cause collapse of the topsoil and formation of discontinuous gullies information about the spatial patterns of collapsed pipes and regional models describing these patterns is still limited therefore this study aims at better understanding the factors controlling the spatial distribution and predicting pipe collapse a dataset with parcels suffering from collapsed pipes n 560 and parcels without collapsed pipes was obtained through a regional survey in a 236 km study area in the flemish ardennes belgium logistic regression was applied to find the best model describing the relationship between the presence absence of a collapsed pipe and a set of independent explanatory variables i e slope gradient drainage area distance to thalweg curvature aspect soil type and lithology special attention was paid to the selection procedure of the grid cells without collapsed pipes apart from the first piping susceptibility map created by logistic regression modelling a second map was made based on topographical thresholds of slope gradient and upslope drainage area the logistic regression model allowed identification of the most important factors controlling pipe collapse pipes are much more likely to occur when a topographical threshold depending on both slope gradient and upslope area is exceeded in zones with a sufficient water supply due to topographical convergence and or the presence of a clay rich lithology on the other hand the use of slope area thresholds only results in reasonable predictions of piping susceptibility with minimum information

morphotectonic development of the marmara region abstract the marmara region of northwest turkey covers the marmara sea basin and the surrounding lands in the region morphologically different areas may be distinguished the marmara sea basin is a structural depression the land to the north is known as the thrace kocaeli peneplain a flatland elevated above a horst this may be referred to as the istanbul horst bounded by two strike slip fault zones which define the structural boundaries of two sea basins the black sea in the north and the marmara sea in the south the southern boundary fault is part of the north anatolian transform fault zone nafz which cuts through the region in the e w direction and extends to the aegean sea region the land to the south of the marmara sea is a plateau about 300 to 800 m high known as the bursa balikesir plateau it has a rather rugged topography represented by nw and ne trending ridges separated by depressions the ridges and the depressions correspond to horsts and grabens respectively the data reveal that the marmara region has passed through the following morphotectonic evolution together with the surrounding region it suffered a long period of denudation between the oligocene and the end of the late miocene which formed a regionwide peneplain the n s extensional regime followed this phase and began to produce a horst graben system and thus fragmented the peneplain the flat lying erosional surfaces have been elevated above the horsts later the nafz reached the marmara region in the initial stage it affected nw anatolia extensively as a wide right lateral shear regime this has evolved and through time the present narrow fault zone has developed the major morphological difference between the regions to the north and the south of the marmara sea basin is mainly related to the nafz as a plate boundary it formed a barrier to the n s extension saving the northern sector from the effect of the extension the southern region has gradually elevated to much higher altitudes

asymmetric slip partitioning in the sea of marmara pull apart a clue to propagation processes of the north anatolian fault between 1939 and 1999 the north anatolian fault naf experienced a westward progression of eight large earthquakes over 800 km of its morphological trace the 2000 km long north anatolian transform fault has also grown by westward propagation through continental lithosphere over a much longer timescale 10 myr the sea of marmara is a large pull apart that appears to have been a geometrical mechanical obstacle encountered by the naf during its propagation the present paper focuses on new high resolution data on the submarine fault system that forms a smaller pull apart beneath the northern sea of marmara between two well known strike slip faults on land izmit and ganos faults the outstandingly clear submarine morphology reveals a segmented fault system including pull apart features at a range of scales which indicate a dominant transtensional tectonic regime there is no evidence for a single continuous purely strike slip fault this result is critical to understanding of the seismic behaviour of this region of the naf close to istanbul additionally morphological and geological evidence is found for a stable kinematics consistent both with the long term displacement field determined for the past 5 myr and with present day anatolia eurasia motion determined with gps however within the sea of marmara region the fault kinematics involves asymmetric slip partitioning that appears to have extended throughout the evolution of the pull apart the loading associated with the westward propagation process of the naf may have provided a favourable initial geometry for such a slip separation

study of siliceous outcrops of meseta del fresco la pampa argentina abstract this paper introduces the results of the study of the silicifications from meseta del fresco fresco formation a vast source of chert in la pampa province argentina that was widely used by hunter gatherer groups from the pampas as a source of raw material petrographic analysis of different thin sections both from geological samples from different parts of the unit as well as from cultural material associated with the outcrops was performed the objective that guided these studies was to develop a detailed description of the type of siliceous replacement upon the prior rock limestone and from the filling of its cavities the results obtained let us inquire about the nature and origin of silicification about the diversity depending on the location in the profile of the carbonate rock replaced during the diagenetic process and about the extent to which this process affected the fresco formation at various points sampled from an archaeological perspective the analysis constitutes an advance in the study of lithic resources procurement behaviors developed by hunter gatherer societies in the past because 1 a database about the characteristics and variations of the silicification present in the outcrop was generated as a tool to compare the archaeological samples from different sites 2 different degrees of rock silicification that could favor its aptitude for knapping were tested this could have motivated preferential selection for making lithic artifacts the archaeological information recorded in different sites on the eastern and western slopes of meseta del fresco is quantified in order to show the differential use of both areas

hydrological controls of surficial mass movements in peat peat deposits occur in areas where water logging is common large areas of blanket mire occur throughout the temperate and cold regions of the northern and southern hemispheres and are particularly extensive in the uk uplands mass movements of peat reported usually as peat slides and bog bursts have been well documented for over 150 years however the fundamental controls of this form of shallow instability are still poorly understood the aim of this paper is to review critically the available evidence linking peat hydrology and slope instability then using data from the north pennine uplands in northern england we examine the importance of rainfall macroscale drainage conditions and peat hydrological processes in initiating slope instability shear failure by loading buoyancy effects basal liquefaction and surface or marginal rupturing have all been proposed as potential failure mechanisms data from northern england demonstrate that hydrological processes are fundamental in determining the spatial and temporal occurrence of peat slides most instabilities are associated with convective summer thunderstorms although instances of rapid snowmelt and intense winter rainfall have also triggered these events all instabilities occur in association with distinct drainage features slides are initiated along natural drainage lines or in association with artificial drainage often brought about by mining activity or agricultural practices at the scale of the soil profile the special hydrological properties of peat in particular shallow water tables and low soil hydraulic conductivity offer important clues to failure mechanisms pore water pressures are generally low and vary little in the peat profile and throughout the year it is clear from observations of subsurface flow that significant volumes of runoff reach considerable depths in the soil macropores flow occurring in pores greater than 1 mm in diameter are important in delivering surface runoff to deeper parts of the profile and in some instances high pipe water pressures may develop these findings define several important hydrological controls for surficial mass movements in peat but the prospect of predicting the location and timing of such events is still a long way off

stream channels in peatlands the role of biological processes in controlling channel form while some aspects of peatlands are well studied understanding of the hydrology and geomorphology of the associated surface drainage networks is quite limited this paper attempts to describe some of the basic attributes of stream channels in peatlands and asks whether the form and the mechanisms behind development represent a significant departure from self forming alluvial streams we use three approaches to better understand these poorly studied systems an examination of the geomorphology of allequash creek wisconsin a survey of aerial photographs of similar peatland stream complexes in northern wisconsin and a review of the existing literature on peat influenced and wetland channels distinct features of allequash creek and other wisconsin streams in peatlands include absence of mineral substrates low width depth ratio presence of lateral pool like structures along the channel margin long straight reaches and acute angle bends further the lateral location of the thalweg was apparently independent of planform or cross sectional form and no flow zones often occurred along both edges of channel cross sections collectively these features represent a distinct departure from characteristic forms of alluvial channels deep peat samples from allequash creek and aerial photographs from other sites indicate that these streams represent remnant lake systems whose basins filled with peat thus we suggest that the processes responsible for channel form in these low energy peatland systems are largely governed by groundwater hydrology and the biology of peat accumulation and decomposition in this manner biological forces not just physical drivers such as channel discharge and sediment supply are central to the understanding of stream geomorphology in peatlands

hydrological hotspots in blanket peatlands spatial variation in peat permeability around a natural soil pipe 1 measurements were made of the hydraulic conductivity k of peat around a natural soil pipe in a blanket bog this is the first investigation of decimeter scale variability in both vertical k and horizontal k in blanket peats which were found to be higher than indicated by previous research this information suggests that it may be appropriate to reconsider i the spatial sampling strategies employed to investigate subsurface flow in blanket peatlands and ii how field data are used to parameterize flow models critically there was spatial structure in the heterogeneity with a wedge of high k peat directly above the pipe forming a hydrological conduit between near surface peat and the perennially flowing pipe there was also significantly greater horizontal k parallel to the pipe s orientation compared with horizontal k perpendicular to the pipe determinations of the triaxial anisotropy of k undertaken for the first time in peat soils revealed substantial directional variations in k the k around the pipe peat interface was investigated however sample length dependency of k for peat samples precluded the investigation of a hypothesized low k skin around the pipe

influence of climate and hydrology on carbon in an early miocene peatland abstract our understanding of the hydrodynamic response of peatland to climate change is restricted to the holocene which confines our knowledge of the fundamental controls on this important carbon reservoir to recent sedimentary successions to understand the interaction of peatland hydrodynamics climate and the carbon cycle on longer time scales a 95 4 m record from lower miocene lignite from the gippsland basin australia is considered 13 c and colour records for the lignite were created by analysing samples every 0 1 m solid state 13 c nmr results indicate that lignite colour is related to the relative abundance of aliphatic carbon the lack of a direct correlation between colour and 13 c demonstrates that the 13 c signal has not been significantly influenced by the diagenetic processes that produce the colour an offset correlation occurs between 13 c and colour with the degree of offset decreasing from 4 5 m at the base to about 0 m at the top this offset is considered to represent a zone of surface influence that extends up to 20 m below the peat surface using numerical modelling we demonstrate that this zone of surface influence and its gradual decline in thickness could arise as a consequence of enhanced fluid flow in regions of high tensile stress within the unconfined peat body the removal of lignin and its derivatives from the zone of surface influence will be favoured by cooler drier periods with lower sea level and high hydraulic gradients across the peatland therefore in the early miocene this peatland acted as a carbon source during global cooling

the moho in the northern basin and range province nevada along the cocorp 40 n seismic reflection transect cocorp seismic reflection profiles across nevada at about 40 n image a prominent essentially continuous band of reflectors at a two way traveltime of 9 to 11 s the approximate correspondence of this reflection time with estimates of the two way traveltime to the moho in this area provided by seismic refraction data suggests that the prominent reflections are from the moho the relief on these reflectors the reflection moho beneath nevada across a latitudinal transect of

dynamics and structural development of metamorphic core complexes the development of metamorphic core complexes mccs in a thickened continental lithosphere is studied using fully coupled thermomechanical numerical code accounting for elastic brittle ductile properties of constituent rocks for mccs to develop the middle lower crust and the sub moho mantle are required to be weak enough to flow laterally so as to simultaneously feed the exhuming dome and enable the moho to keep a flat geometry the conditions are satisfied with initial moho temperatures of 800 c or higher with crustal thicknesses of 45 km or greater and with initial effective viscosities lower than 1020 pa s and 1022 pa s in the lower crust and the underlying mantle respectively a compositional mainly density anomaly with the properties of granite is placed centrally in the crust to localize strain at the onset of deformation during a first stage of upper crust necking the deformation pattern is relatively symmetrical and dominated by graben formation in the upper crust when the first ductile layers reach the surface a second stage of dome amplification and widening occurs dome amplification is accommodated by horizontal flow in the ductile crust giving an early symmetrical pattern of conjugate shear zones with no obvious detachment zone the system then rapidly becomes asymmetric with the localization of a detachment zone along one dome limb further accommodating dome widening thus the exhumation process of a metamorphic dome results in the progressive development of a detachment zone depending on initial moho temperature the detachment zone can migrate in space or die out and be replaced by a new one with an opposite dip

controls on the spatial distribution of natural pipe outlets in heavily degraded blanket peat abstract natural soil pipes are recognised as a common geomorphological feature in many peatlands and they can discharge large quantities of water and sediment however little is known about their morphological characteristics in heavily degraded peat systems this paper presents a survey of pipe outlets in which the frequency and extent of natural soil pipes are measured across a heavily gullied blanket peat catchment in the peak district of northern england over a stream length of 7 71 km we determined the occurrence and size of 346 pipe outlets and found a mean frequency of 22 8 km 1 gully bank topographic position was an important control on the size and depth of pipe outlets aspect had a large influence on pipe outlet frequency with southwest and west facing gully banks hosting more than 43 of identified pipe outlets pipe outlets on streambanks with signs of headward retreat were significantly larger and closer to the peat surface compared to pipe outlets that issued onto uniform streambank edges we suggest that larger pipe frequencies are observed on gully banks that are more susceptible to desiccation cracking and propose that future peatland restoration works could prioritise mitigating against pipe formation by revegetating and reprofiling south and west facing gully banks

crustal thickness variations in the aegean region and implications for the extension of continental crust 1 we installed 5 broadband and 45 short period temporary seismic stations distributed partly as a dense 100 km long n s linear array and partly as a regional network throughout the menderes massif of western turkey in order to study crust upper mantle structure and seismicity in this study we have combined teleseismic waveform data from these stations with data from several permanent seismic stations to determine crustal thickness variations in the aegean region receiver function studies at seven broadband stations using the h stacking method have yielded crustal thicknesses and vp vs ratios over a broad region of the aegean a more detailed crustal image was obtained in the central menderes massif where we applied common conversion point stacking to receiver functions obtained from the n s linear array the results show a general trend of westward crustal thinning from 36 km in central anatolia to 28 30 km in the central menderes massif to 25 km beneath the aegean sea the results also indicate that crustal thinning in the aegean is not uniform in the n s extensional direction the crust is thinner in the central menderes massif 28 30 km of crustal thicknesses and the cycladic massif 25 26 km than in surrounding regions where crustal thicknesses are 32 34 km the long lived elevated moho under the metamorphic core complexes suggests that the lower crust in the aegean region is at least 3 times more viscous than that in the basin and range province where the moho is much flatter

love wave group velocity maps of turkey and surrounding regions summary we present the analysis of a love wave dispersion study performed across turkey and the surroundings group velocity dispersion curves were obtained from the local and regional earthquakes recorded at both permanent and temporary stations operated in the region lovewave group velocity maps in the period range of 10 50 s were computed using a tomographic inversion method the study shows the existence of significantly different crustal types in the area the group velocity anomalies are associated with the major geological structures in the region low group velocities at shorter periods 10 20 s are observed in the local sedimentary basins the eastern mediterranean and the black sea the eastern anatolia region is also characterized by low group velocities while pontides and bitlis p ot urge massif display higher group velocities the central anatolia exhibits uniform velocity distribution indicating more homogenous crust the isparta angle is marked by a wedge shaped low group velocity anomaly the low velocities observed in the isparta angle are related to crustal thickening and subduction related complex high velocities observed on the maps are associated with metamorphics magmatic arcs along the orogenic belts of pontides p

anisotropy and depth related heterogeneity of hydraulic conductivity in a bog peat i laboratory measurements anisotropy and heterogeneity of hydraulic conductivity k are suspected of greatly affecting rates and patterns of ground water seepage in peats a new laboratory method termed here the modified cube method was used to measure horizontal and vertical hydraulic conductivity kh and kv of 400 samples of bog peat the new method avoids many of the problems associated with existing field and laboratory methods and is shown to give relatively precise measurements of k in the majority of samples tested kh was much greater than kv indicating that the bog peat was strongly anisotropic log10kh log10kv and log10 kh kv were found to vary significantly with depth although none of the relationships was simple we comment on the scale dependency of our measurements

characteristics and consequences of flow in the lower crust in some places there is strong evidence that the lower continental crust has flowed so as to smooth out variations in crustal thickness caused by differential crustal extension or shortening in order to better understand the processes involved we investigate the behavior of a fluid layer over a fluid half space to see how such a system responds to the deformation of its upper and lower boundaries this simple system can be used to study both the decay of crustal thickness contrasts and the behavior of a thin lithospheric sheet the changing response of the system to variations in density and viscosity contrasts and to different boundary conditions imposed on the fluid interface can easily be studied analytically the most important results are that variations in crustal thickness on a wavelength of a few times the thickness of the flowing channel will decay quickest and that large lateral variations in crustal thickness cause the fluid to develop a steep front which may cause a topographic step above it at the earth s surface deformation within the channel will be principally by simple shear the clear association of lower crustal flow with regions of thickened crust and magmatic activity suggests that both can reduce the viscosity of the lower crust to levels at which flow can occur the smoothing of crustal thickness contrasts leads to differential vertical motions and is thus a method by which substantial tilting can occur without faulting this differential uplift may be responsible for rotating and exhuming some of the detachment faults in metamorphic core complexes in the basin and range province of the western united states it is also a method of causing structural inversion in basins that does not require the reactivation of normal faults as thrusts or reverse faults

an analog experiment for the aegean to describe the contribution of gravitational potential energy the southern aegean seafloor exhibits clear evidence of internal deformation stretching as shown by tectonics seismology and space geodesy we use an analog three layer laboratory experiment of sand silicone putty and honey to investigate the deformation of the southern aegean lithosphere the model is installed in a box and confined by a vertical wall we open a gate in the wall and observe the deformation of the two upper layers due to buoyancy forces the general pattern of the deformation of the southern aegean is found in the analog model we observe the formation of an arc spreading outward with time the extension is radial in the inner part but parallel to the arc in the external part and of comparable importance at both ends of the gate we observe strike slip motion dextral in the western part sinistral in the eastern part rotation clockwise in the western part counterclockwise in the eastern part of up to 40 is seen on both sides of the gate but is also present with a smaller amplitude far in the internal region partially due to distributed shear the spreading is associated with the thinning of the two upper layers and affects a region of dimensions comparable to the length of the free boundary this spreading does not propagate inward with time some pieces of material located near the active boundary remain undeformed during the experiment

deformation of western turkey from a combination of permanent and campaign gps data limits to block like behavior 1 we present a new geodetic velocity field covering western turkey south of the north anatolian fault our velocity field is derived from a combination of continuously recording gps stations operating since 2003 survey type gps measurements carried out in the period 1997 2005 and velocities from reilinger et al 2006 the velocity field indicates that western turkey currently undergoes extension whose rate increases from the anatolia plateau to the aegean coast the overall extension in westernmost turkey is about 20 mm yr making it one of the fastest areas of continental extension in the world we test whether the observed deformation is better represented by the rotation of crustal blocks or by more distributed deformation while no deformation is detected in the central anatolian plateau we observe a deformation field west of the plateau that cannot be explained by block models unless the blocks are so small as to be essentially indistinguishable from a continuum although concentration of strain rates up to 140 nstrain yr are found across the major grabens strain rates above 50 nstrain yr are found throughout western turkey the distributions of topography and crustal thickness in western turkey agree with the distributions expected if the crust there had a constant thickness at 5 ma equal to that of the present central anatolian plateau and had subsequently been thinned at the present day distribution of strain rates our results therefore suggest that extensional strain affects the whole continental lithosphere of western turkey rather than being restricted to a small number of block boundaries

metamorphic core complexes of cordilleran type in the cyclades aegean sea greece the islands of ios and naxos in the cycladic archipelago greece contain elongate domes over which a pervasive north to north northeast stretching lineation is warped these islands may be metamorphic core complexes of cordilleran type involving middle crustal rocks drawn upward and outward from underneath the sedimentary basins now 100 km to the south from ca 25 ma onward during uplift the crystalline rocks now exposed on the islands were deformed noncoaxially in the deeper levels of a major shallow dipping ductile shear zone this shear zone may have connected with low angle normal faults in its upper levels because it is probable that its later history involved the metamorphic complexes being dragged out from under a stretching and fracturing upper plate composed mainly of unmetamorphosed sedimentary and ophiolite suite rocks this model can be extended to explain the exhumation of the high pressure low temperature metamorphic rocks on crete which with the cyclades forms a distended paired metamorphic belt separated by an active sedimentary basin

application of ground penetrating radar to the identification of subsurface piping in blanket peat natural soil pipes are common and significant in upland blanket peat catchments yet there are major problems in finding and defining the subsurface pipe networks this is particularly important because pipeflow can contribute a large proportion of runoff to the river systems in these upland environments and may significantly influence catchment sediment and solute yields traditional methods such as digging soil pits are destructive and time consuming particularly in deep peat and only provide single point sources of information this paper presents results from an experiment to assess the use of ground penetrating radar gpr to remotely sense pipes in blanket peat the technique is shown to be successful in identifying most of the pipes tested in the pilot catchment comparison of data on pipes identified by gpr and verified by manual measurement suggests that pipes can be located in the soil profile with a depth accuracy of 20 to 30 cm gpr identified pipes were found throughout the soil profile however those within 10 20 cm of the surface could not be identified using the 100 or 200 mhz antennae due to multiple surface reflections generally pipes smaller than 10 cm in diameter could not be identified using the technique although modifications are suggested that will allow enhanced resolution future work would benefit from the development of dual frequency antennae that will allow the combination of high resolution data with the depth of penetration required in a wetland environment the gpr experiment shows that pipe network densities were much greater than could be detected from surface observation alone thus gpr provides a non destructive fast technique which can produce continuous profiles of peat depth and indicate pipe locations across survey transects copyright 2002 john wiley sons ltd

blanket peat erosion in a mid wales catchment during two drought years the rate of blanket peat erosion was measured at an upland site in central wales during the 1983 1984 drought years erosion pins a peat surface sediment trap and sediment sampling in the effluent stream were used to estimate the rate of peat surface recession and the rate of organic sediment loss from the catchment an overall rate of surface recession of 16 mm y 1 on exposed peat faces was recorded this differed between faces of different aspects with the greatest recession on southwest faces eroding peat surfaces exhibited maximum recession during the summer but the peat surface sediment trap indicated that the highest rates of sediment loss from peat faces due to rain wash occurred during the autumn and early winter stream sediment sampling showed that the yield of organic sediment from the catchment was 34 4 t km 2 yr 1 with greatest losses also during the autumn and early winter the evidence suggested that the surface recession as measured on erosion pins included a wastage or shrinkage component which possibly accounted for as much as 80 per cent of the apparent loss direct and circumstantial evidence suggested that peat wastage during the summer months was the most important agent of surface recession in the study period which encompassed the two dry summers desiccation provided available sediment during the autumn but organic sediment supply became limited as the winter progressed despite the occurrence of frost heave

moho crustal architecture and deep deformation under the north marmara trough from the seismarmara leg 1 offshore onshore reflection refraction survey abstract understanding further the nature and evolution at lithospheric scale of the sea of marmara on the north anatolian fault needs constraints on the deep crustal and moho spatial variation this has been probed here with offshore onshore and obs ocean bottom seismometer refraction seismics in addition to coincident mcs marine multichannel reflection seismic profiles over the whole north marmara trough the diverse strikes of mcs profiles in a dense grid allow to avoid misinterpretation of late echoes in the deep basin as moho reflections and attribute them to sidesweeps moho is instead positively identified from reversed observations of first arrival head and refracted waves at the top of the mantle obtained at large offset by land stations a significant and sharp reduction in its depth on the order of 5 km occurs beneath both the eastern and western rims of the north marmara trough with a more progressive crustal thinning from the south the wide angle reflections on obs and land stations document in addition to moho the top of a lower crustal reflective layer which is also sampled by mcs profiles and appears to follow moho topography the dense grid of mcs profiles along the southwestern margin of the north marmara trough reveals a dipping reflector through the upper crust with tilted basement blocks on top this low angle fault is suggested as a normal sense detachment extending in depth towards the reflective lower crust the upwarp of the moho and lower crustal layer towards the north marmara trough suggests that crustal thinning occurs mostly in the upper crustal part with lateral transport of the material towards wsw in the footwall of the detachment and possibly other features to the south in the motion of anatolia with respect to stable eurasia oblique to the north marmara trough thinning can be accommodated in an asymmetric partitioning of the displacement on several branching faults at lithospheric scale

influence of the geologic and geomorphologic characteristics and of crab burrows on the interrelation between surface water and groundwater in an estuarine coastal wetland the interrelation between surface water and groundwater in intertidal flats is often studied through mathematical models in many cases these models need to be supported by an integral analysis of the geologic geomorphologic hydrologic and biological characteristics of the environment that are to be obtained from field surveys the marshy environment of the river ajo in the samborombon bay wetland argentina is a typical example of an estuarine coastal zone geologic and geomorphologic surveys were carried out as well as measurements of surface water and groundwater level changes as a response of the aquifer to tidal forcing the banks of the river ajo are either scarped with storm flats or mildly sloped with intertidal flats and numerous crab burrows sediments are mainly silty clayey with low permeability and lie over silty sandy layers at the erosion scarps the tidal wave enters the aquifer as a sub horizontal flow through the pore space of the sediments the tidal range in the aquifer depends on the lithological characteristics of the sediments and on the side changes of their hydraulic conductivity the rise of the water table at high water and its subsequent fall are nearly sinusoidal with a period similar to that of the tide at the river at the intertidal flats instead the tidal wave enters the aquifer mainly as a sub vertical flow through the crab burrows as the crab burrows are not interconnected they are not distinct pathways for preferential flow therefore the groundwater flux into the river is very slow during low water and the recovery of the water table takes a long time the tidal influence upon the water table on both kinds of banks affects only a narrow strip of the aquifer not only are the characteristics of the marshy environment of the river ajo representative of most of the samborombon bay wetland they can also be extended to other similar coastal wetlands to help preserve these invaluable environments

seismic evidence for an ancient rift beneath the cumberland plateau tennessee a detailed analysis of broadband teleseismic p waveforms broadband receiver functions developed from teleseismic p waveforms recorded on the midperiod passband of regional seismic test network station rscp are inverted for vertical velocity structure beneath the cumberland plateau tennessee the detailed broadband receiver functions are obtained by stacking source equalizd horizontal components of teleseismic p waveforms the resulting receiver functions are most sensitive to the shear velocity structure near the station a time domain inversion routine utilizes the radial receiver function to determine this structure assuming a crustal model parameterized by many thin flat lying homogeneous layers lateral changes in structure are identified by examining azimuthal variations in the vertical structure the results reveal significant rapid lateral changes in the midcrustal structure beneath the station that are interpreted in relation to the origin of the east continent gravity high located northeast of rscp the results from events arriving from the northeast show a high velocity midcrustal layer not present in results from the southeast azimuth this velocity structure can be shown to support the idea that this feature is part of a keweenawan rift system another interesting feature of the derived velocity models is the indication that the crust mantle boundary beneath the cumberland plateau is a thick probably laminated transition zonemore between the depths of 40 and 55 km a result consistent with interpretations of early refraction work in the area less

global positioning system constraints on plate kinematics and dynamics in the eastern mediterranean and caucasus we present and interpret global positioning system gps measurements of crustal motions for the period 1988 1997 at 189 sites extending east west from the caucasus mountains to the adriatic sea and north south from the southern edge of the eurasian plate to the northern edge of the african plate sites on the northern arabian platform move 18 2 mm yr at n25 5 w relative to eurasia less than the nuvel 1a circuit closure rate 25 1 mm yr at n21 7 w preliminary motion estimates 1994 1997 for stations located in egypt on the northeastern part of africa show northward motion at 5 6 2 mm yr also slower than nuvel ia estimates 10 1 mm yr at n2 4 e eastern turkey is characterized by distributed deformation while central turkey is characterized by coherent plate motion internal deformation of 2 mm yr involving westward displacement and counterclockwise rotation of the anatolian plate the anatolian plate is de coupled from eurasia along the right lateral strike slip north anatolian fault naf we derive a best fitting euler vector for anatolia eurasia motion of 30 7 0 8 n 32 6 0 4 e 1 2 0 1 myr the euler vector gives an upper bound for naf slip rate of 24 1 mm yr we determine a preliminary gps arabia anatolia euler vector of 32 9 1 2 n 40 3 1 1 e 0 8 0 2 myr and an upper bound on left lateral slip on the east anatolian fault eaf of 9 1 mm yr the central and southern aegean is characterized by coherent motion internal deformation of 2 mm yr toward the sw at 30 1 mm yr relative to eurasia stations in the se aegean deviate significantly from the overall motion of the southern aegean showing increasing velocities toward the trench and reaching 10 1 mm yr relative to the southern aegean as a whole

piping and pipeflow in a deep peat catchment abstract natural pipes are common in many upland blanket peats yet little is known about pipe network morphology or pipeflow processes most information on soil piping comes from the shallow peaty podzols of the welsh uplands where monitoring suggests that pipes may be important contributors to streamflow this paper presents information on piping and pipeflow from a deep upland blanket peat catchment in the pennine hills of northern england pipe outlets are found throughout the soil profile ranging from the underlying substrate at 3 m depth to pipes which are within a few centimetres of the surface mean pipe diameters range from 3 to 70 cm some pipes are over 150 m long slopes in the catchment are less steep than those usually associated with soil piping continuous flow records were obtained from 15 gauging sites on 8 separate pipes the pipeflow response from deep blanket peat was found to be different to that reported in the shallow peaty podzols of the welsh uplands the distinction between ephemeral and perennial pipe types does not appear to be useful within the deep pennine blanket peat response times from all of the pipes are short even from pipes deep within the peat at the same time pipes have a prolonged recession limb such that they maintain low flow for longer periods than most other runoff production processes within the catchment pipeflow contributes around 10 of the streamflow volume but can at times contribute up to 30 soil pipes may therefore be far more important in some upland peat catchments than previous work has hitherto suggested

southern african crustal evolution and composition constraints from receiver function studies 1 stacking of approximately 1500 radial receiver functions recorded at about 80 broadband seismic stations deployed in southern africa reveals systematic spatial variations in the ratio of crustal p and s wave velocities crustal thickness h and the amplitude of the converted moho phases r the eastern zimbabwe and the southern kaapvaal cratons are characterized by small h 38 km small 1 73 and large r 0 15 values suggesting that the relatively undisturbed archean crust beneath southern africa is separated from the mantle by a sharp moho and is felsic in composition the limpopo belt which was created by a collisional event at 2 7 ga displays large h 43 km but similar and r values relative to the cratonic areas the bushveld mafic intrusion complex and its surrounding areas show large 1 78 large h 43 km and small r 0 11 values reflecting the intrusion of mafic material into the original crust as a result of the bushveld event at 2 05 ga excluding the bushveld the spatially consistent and age independent low accentuate the difference between felsic crustal composition and more mafic island arcs that are thought to be the likely source of continental material within such an island arc model our data combined with xenolith data excluding mantle delamination in cratonic environments suggest that the modification to a felsic composition e g by the partial melting of basalt and removal of residue by delamination is restricted to have occurred during the collision between the arcs and the continent

gps constraints on continental deformation in the africa arabia eurasia continental collision zone and implications for the dynamics of plate interactions 1 the gps derived velocity field 1988 2005 for the zone of interaction of the arabian african nubian somalian and eurasian plates indicates counterclockwise rotation of a broad area of the earth s surface including the arabian plate adjacent parts of the zagros and central iran turkey and the aegean peloponnesus relative to eurasia at rates in the range of 20 30 mm yr this relatively rapid motion occurs within the framework of the slow moving 5 mm yr relative motions eurasian nubian and somalian plates the circulatory pattern of motion increases in rate toward the hellenic trench system we develop an elastic block model to constrain present day plate motions relative euler vectors regional deformation within the interplate zone and slip rates for major faults substantial areas of continental lithosphere within the region of plate interaction show coherent motion with internal deformations below 1 2 mm yr including central and eastern anatolia turkey the southwestern aegean peloponnesus the lesser caucasus and central iran geodetic slip rates for major block bounding structures are mostly comparable to geologic rates estimated for the most recent geological period 3 5 myr we find that the convergence of arabia with eurasia is accommodated in large part by lateral transport within the interior part of the collision zone and lithospheric shortening along the caucasus and zagros mountain belts around the periphery of the collision zone in addition we find that the principal boundary between the westerly moving anatolian plate and arabia east anatolian fault is presently characterized by pure left lateral strike slip with no fault normal convergence this implies that extrusion is not presently inducing westward motion of anatolia on the basis of the observed kinematics we hypothesize that deformation in the africa arabia eurasia collision zone is driven in large part by rollback of the subducting african lithosphere beneath the hellenic and cyprus trenches aided by slab pull on the southeastern side of the subducting arabian plate along the makran subduction zone we further suggest that the separation of arabia from africa is a response to plate motions induced by active subduction

hydrological connectivity of soil pipes determined by ground penetrating radar tracer detection soil pipes are common and important features of many catchments particularly in semi arid and humid areas and can contribute a large proportion of runoff to river systems they may also signi cantly in uence catchment sediment and solute yield however there are often problems in nding and de ning soil pipe networks which are located deep below the surface ground penetrating radar gpr has been used for non destructive identi cation and mapping of soil pipes in blanket peat catchments while gpr can identify subsurface cavities it cannot alone determine hydrological connectivity between one cavity and another this paper presents results from an experiment to test the ability of gpr to establish hydrological connectivity between pipes through use of a tracer solution sodium chloride was injected into pipe cavities previously detected by the radar the gpr was placed downslope of the injection points and positioned on the ground directly above detected soil pipes the resultant radargrams showed signi cant changes in re ectance from some cavities and no change from others pipe waters were sampled in order to check the radar results changes in electrical conductivity of the pipe water could be detected by the gpr without data post processing when background levels were increased by more than approximately twofold it was thus possible to rapidly determine hydrological connectivity of soil pipes within dense pipe networks across hillslopes without ground disturbance it was also possible to remotely measure travel times through pipe systems the passing of the salt wave below the gpr produced an easily detectable signal on the radargram which required no post processing the technique should allow remote sensing of water sources and sinks for soil pipes below the surface the improved understanding of owpath connectivity will be important for understanding water delivery solutional and particulate denudation and hydrological and geomorphological model development copyright 2004 john wiley sons ltd

travel time tomography of the european mediterranean mantle down to 1400 km abstract the 3 d p wave velocity structure of the mantle below europe the mediterranean region and a part of asia minor is investigated this study is a considerable extension of an earlier tomographic experiment that was limited to imaging upper mantle structure only here the earth s volume under study encompasses the mantle to a depth of 1400 km and we increase the number of international seismological centre isc data for inversion by a factor of four by taking more years of observation and by including data from teleseismic events the most important departure from the earlier study is that we do not use the jeffreys bullen model as a reference model but an improved radially symmetric velocity model the pm2 model which is appropriate for the european mediterranean mantle our inversion procedure consists of two steps first the radial model pm2 is determined from the isc delay times by a nonlinear trial and error inversion of the data as opposed to the jeffreys bullen model the new reference model has a high velocity lithosphere a low velocity zone and seismic discontinuities at depths of 400 and 670 km next the isc data are corrected for effects related to the change in reference model and inverted for 3 d heterogeneity relative to the pm2 model we follow this two step approach to attain a better linearizable tomographic problem in which ray paths computed in the pm2 model provide a better approximation of the actual ray paths than those computed from the jeffreys bullen model hence the two step scheme leads to a more credible application of fermat s principle in linearizing the tomographic equations inversion results for the 3 d heterogeneity are computed for both the uncorrected isc data and for the pm2 data the data fit obtained in the two step approach is slightly better than in the inversion of isc data using the jeffreys bullen reference model a comparison of the tomographic results demonstrates that the pm2 data inversion is to be preferred to assess the spatial resolution an analysis is given of hit count patterns sampling of the mantle by ray paths and results of sensitivity tests with 3 d synthetic velocity models the spatial resolution obtained varies with position in the mantle and is studied both in map view and in cross section in the well sampled regions of the mantle the spatial resolution for larger scale structure can qualitatively be denoted as reasonable to good and at least sufficient to allow interpretation of larger scale anomalies a comparison is made of the results of this study with independent models of s velocity heterogeneity obtained in a number of investigations and with a prediction of the seismic velocity structure of the mantle computed from tectonic reconstructions of the mediterranean region in the context of this comparison interpretations of large scale positive anomalies found in the mediterranean upper mantle in terms of subducted lithosphere are given specifically addressed are subduction below southern spain below the western mediterranean and italy and below the aegean in the last region a slab anomaly is mapped down to depths of 800 km

ground penetrating radar and spring formation in a groundwater dominated peat wetland summary ground penetrating radar gpr was used to identify the thickness and geometry of peat in a groundwater fed wetland in northern wisconsin the low electrical conductivity of the water saturated peat permitted high resolution imaging to a depth of 16 m the gpr survey results delineated a break in slope in the interface between peat and the underlying sand gravel springs and ponds are located above the break in slope suggesting that thinning of the sand and gravel may focus groundwater flow upward to the wetland surface with emergence as springs the results of the gpr surveys suggests a potential mechanism that controls the formation of large springs and pools above the break in slope