testing the sensitivity of geomorphic indices in areas of low rate active folding eastern betic cordillera spain abstract active deformation structures have an incidence in topography that can be quantified by using geomorphic indices most of these indices have been checked in faulted regions with high deformation rates the application of several geomorphic indices hypsometric curve analysis normalized stream length gradient and valley width to valley height ratio to the drainage network of the southern limb of the sierra de las estancias antiform internal zones eastern betic cordillera where low rate active folding has been recognized allows us to investigate the suitability of these indices to identify active structures in such a scenario hypsometric curves clearly identify regions with recent uplift and young topography but they do not provide any constraint on the location of active folds local valley width to valley height index variations have been detected just coinciding whit the position of ene wsw active folds normalized stream length gradient index serves to locate active folds in areas of hard rock substratum but not in those areas with soft sediments neogene quaternary sedimentary basins this is most likely due to the fact that in the basins erosion is much more intense than in the hard rock sectors in view of these results we consider that geomorphic indices constitute a valuable tool for identifying sectors affected by low rate uplift related to active folding with the best results obtained in hard rock areas

the effects of rock uplift and rock resistance on river morphology in a subduction zone forearc oregon usa relationships between riverbed morphology concavity rock type and rock uplift rate are examined to independently unravel the contribution of along strike variations in lithology and rates of vertical deformation to the topographic relief of the oregon coastal mountains lithologic control on river profile form is reflected by convexities and knickpoints in a number of longitudinal profiles and by general trends of concavity as a function of lithology volcanic and sedimentary rocks are the principal rock types underlying the northern oregon coast ranges between 46 30 and 45 n where mixed bedrock alluvial channels dominate average concavity is 0 57 in this region in the alluviated central oregon coast ranges between 45 and 44 n values of concavity are on average the highest 0 82 south of 44 n however bedrock channels are common and 0 73 mixed bedrock alluvial channels characterize rivers in the klamath mountains from 43 n south 0 64 rock uplift rates of 0 5 mm a 1 mixed bedrock alluvial channels and concavities of 0 53 0 70 occur within the northernmost coast ranges and klamath mountains for rivers flowing over volcanic rocks 0 53 and 0 72 for reaches crossing sedimentary rocks whereas channel type and concavity generally co vary with lithology along much of the range rivers between 44 5 and 43 n do not follow these trends concavities are generally greater than 0 70 alluvial channels are common and river profiles lack knickpoints between 44 5 and 44 n despite the fact that lithology is arguably invariant moreover rock uplift rates in this region vary from low 0 5 mm a 1 to subsidence 0 mm a 1 these observations are consistent with models of transient river response to a decrease in uplift rate conversely the rivers between 44 and 43 n have similar concavities and flow on the same mapped bedrock unit as the central region but have bedrock channels and irregular longitudinal profiles suggesting the river profiles reflect a transient response to an increase in uplift rate if changes in rock uplift rate explain the differences in river profile form and morphology it is unlikely that rock uplift and erosion are in steady state in the oregon coastal mountains copyright 2006 john wiley sons ltd

morphological and morphometric approach to the study of the structural arrangement of northeastern abruzzo central italy abstract the morphotectonic research at the dipartimento di scienze della terra of the universita di roma la sapienza aims to define the role of tectonics and neotectonics in the morphological evolution of central italy in this context the relationships between morphology and tectonics have been investigated in an area of northern abruzzo extending from the apennine chain to the adriatic sea morphological and morphometric analyses carried out show that the geomorphological evolution of the study area was strongly affected by tectonics especially recently the most recent extensional tectonics intersect the previous compressive structures overthrust reverse faults folds strike slip faults determining the structural arrangement characterized by uplifted and downthrown blocks morphological analysis shows that extentional tectonics occurred with the following alignments nw se nnw sse ne sw ene wsw n s and e w the spatial variability of amplitude of relief values corroborated the observations obtained from previous analyses in particular the existence of different blocks differentially uplifted along the alignments mentioned above finally data obtained through the statistical analysis of preferred stream orientations confirm the previous considerations showing that the same tectonic directions markedly influenced the drainage network development streams of lower order preferentially follow the n s and e w directions which suggests that these tectonic trends were active until very recent times at least up to the late pleistocene the results obtained testify both to the effectiveness of the methodological approach and the likelihood of the proposed morphotectonic arrangement of the study area

systematic variation of bedrock channel gradients in the central oregon coast range implications for rock uplift and shallow landsliding abstract in tectonically active regions bedrock channels play a critical role in dictating the pace of landscape evolution models of fluvial incision into bedrock provide a means of investigating relationships between gradients of bedrock channels and patterns of active deformation variations in lithology orographic precipitation sediment supply and erosional processes serve to complicate tectonic inferences derived from morphologic data yet most tectonically active landscapes are characterized by these complexities in contrast the central oregon coast range ocr which is situated above the cascadia subduction zone has experienced rock uplift for several million years did not experience pleistocene glaciation boasts a relatively uniform lithology and exhibits minor variations in precipitation although numerous process based geomorphic studies suggest that rates of erosion across the ocr are relatively constant it has not been demonstrated that bedrock channel gradients in the region exhibit spatially consistent values analysis of broadly distributed small drainage basins 5 20 km in the central ocr enables us to explore regional variability in bedrock channel gradients resulting from differential rock uplift or other sources consistent with previous studies that have documented local structural control of deformed fluvial terraces in the western portion of our study area our data reveal a roughly 20 km wide band of systematically elevated channel slopes roughly twice the background value roughly coincident with the strike of n s trending mapped folds although many factors could feasibly generate this pattern including variable rock strength precipitation gradients or temporal or spatial variations in forearc deformation the elevated bedrock channel slopes likely reflect differential rock uplift related to activity of local structures importantly our analysis suggests that rock uplift and erosion rates may vary systematically across the ocr although our calculations were focused on the fluvial dominated portion of study basins our results have implications for upstream areas including unchanneled valleys that often serve as source areas for long runout debris flows zero order basins or topographic hollows within the n s trending band of elevated channel slopes tend to be steeper than adjacent areas and may experience more frequent evacuation by shallow landsliding thus this region of the ocr may be highly sensitive to land use practices and high intensity rainstorms

geomorphological response of fluvial and coastal terraces to quaternary tectonics and climate as revealed by geostatistical topographic analysis geostatistical topographic analysis is widely recognized as a useful tool for the statistical reconstruction of planar geomorphic markers from relict surfaces this work is aimed at improving the geostatistical approach used in previous works and developing a method for evaluating the incision rates of rivers in their lower catchments during the late quaternary we chose the major valleys of the adriatic foothills central italy affected since late miocene by a differential tectonic uplift which is still active in particular i we applied the geostatistical analysis to reconstruct the original top surfaces of fluvial to coastal terrace bodies at the metauro river and cesano river mouths ii we performed correlations between the height distribution of the alluvial terrace sequences and the quaternary climatic curve to estimate the average long term fluvial incision rates in the lowermost reaches of the metauro cesano misa and esino rivers the obtained averaged incision rates have been interpreted also in the light of the stream length gradient index sl index steepness index ks and concavity index as proxies of the stream power per unit length results confirm that geostatistical and terrain analysis of topographic and geometric arrangements of fluvial and coastal terraces is an effective tool in detecting geomorphic and tectonic factors inducing perturbations on planar geomorphic markers in particular we better delineated the surface geometry and boundaries of well developed coastal fans at the mouths of the metauro and cesano rivers already recognized in previous works through sedimentological morphostratigraphic and chronological data moreover we found evidence for cut and fill phases that took place during and immediately after the river aggradation of the late quaternary glacial periods despite the slope area analysis evidenced a widespread influence of the regional differential uplift on single river basin configuration we observed some space and time variability of averaged incision rates for adjacent valleys mainly explained by physiographic configuration and dynamics of drainage network copyright 2011 john wiley sons ltd

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

morphotectonic approach to the drainage analysis in the north marche region central italy abstract the umbro marchean apennines form an arcuate nw se fold and thrust belt of ne convexity the orogen developed from the early miocene and shortened the more than 5 km thick meso cenozoic stratigraphic succession by about 30 the internal part of the mountain chain is however overprinted by sw dipping extensional normal faults that bound the plio pleistocene continental basins nevertheless the distribution of river terraces all along the main river valleys clearly indicates that middle upper pleistocene and holocene vertical uplift dominated over local anticlinal uplift for the entire studied area the drainage network of the marche region in the external part of the umbro marchean apennines has an overall sub parallel pattern oriented mainly sw ne and transversely breaches the main calcareous anticlinal ridges before reaching the adriatic coast emergence and drainage initiation may have begun as early as the messinian cave systems formed during the erosion history and document former stream levels the breaching of the high amplitude anticlinal ridges was controlled mainly by joint systems and locally by nne ssw striking faults in turn both superimposition and stream piracy phenomena could have played a significant control in the drainage network development and in places complex mechanisms involving antecedence cannot be ruled out for streams bypassing anticlinal ridges

morphotectonic evolution of the adriatic piedmont of the apennines an advancement in the knowledge of the marche abruzzo border area abstract this study focuses on the morphotectonic evolution of the apennines central adriatic piedmont and in particular on the region along the marche abruzzo border stratigraphically the rocks of this area are typical of a marine environment which characterised the central periadriatic basin up to the early pleistocene a differential regional uplift produced a north eastward tilting of the area this led to the development of a parallel drainage network across the emerged coastal plain during the middle pleistocene these tectonic events along with a series of climatic changes during the quaternary caused alternating phases of fluvial incision and deposition which eventually produced four levels of fluvial terraces as outcropping lithologies seldom display a full record of significant tectonic deformation we carried out morphometric analysis along with a geomorphological survey in order to enhance our morphotectonic understanding of the area and to better define the role of neotectonics in the morphological evolution of the area we also analysed the morphological evidence of tectonics including field surveys focusing on fluvial and alluvial fan terraces as they are valuable indicators of neotectonic evolution finally we employed geostatistical analysis to facilitate the detection of fluvial terraces even when affected by neotectonics our results indicate an active control on drainage evolution by nw se to wnw ese tectonic lineaments intersected by sw ne and wsw ene ones these tectonic lines continued to be active up to the formation of the third level of terraces late pleistocene river captures and diversions followed during the late pleistocene and the holocene in some cases favoured by passive tectonic control

analysis of digital elevation data for palaeosurfaces in south western sweden a 3873 km large rectangular area of the precambrian basement in south western sweden has been investigated regarding gross morphology of palaeosurfaces gis and digital elevation data were used to

an automated method to extract fluvial terraces from digital elevation models the vesdre valley a case study in eastern belgium abstract fluvial terraces are a powerful tool for unraveling the combined tectonic and climatic conditions that controlled directly or indirectly the quaternary incision of rivers terrace long profiles are usually retrieved from sparse traces of ancient floodplains preserved in the present topography however when these traces classically collected from topographic maps aerial photographs and field analyses are too few the inferred profiles may be questionable yet the now available high quality and high resolution digital elevation models dems offer an opportunity to increase greatly the quantity of information usable to reconstruct terrace profiles therefore the purpose of this study was to develop a new dem based method of terrace recognition in order to create a larger database and better constrain the profile reconstruction moreover particular procedures of image and numerical processing were defined to fully automate the analysis basically our method relies on the production of bivariate scatter plots depicting the relation between slope and relative altitude i e the altitude above the current alluvial plain for all pixels of successive sections of the valley for each scatter plot the curve of the lowest slope values observed at every relative altitude is smoothed and its minima are assumed to locate the altitudes of the terrace elements preserved in the section we successfully tested this method in the vesdre valley incised in the ne ardenne massif e belgium notably identifying fault deformation of the profiles the main advantages of our approach are its objectivity exhaustiveness and rapidity allowing fast and coherent analysis of many rivers over extended regions

density contrasts in the upper mantle and lower crust across the continent ocean transition constraints from 3 d gravity modelling at the norwegian margin summary 3 d gravity models that consider the highly complex density structure of the norwegian passive volcanic continental margin require a significantly lower density in the mantle below the ocean than below the continent this is especially pronounced on the crust free residual gravity anomalies obtained by 3 d gravity stripping this density contrast in the mantle indicates different physical properties either related to thermal or compositional conditions beneath the two domains we assess the gravity response of thermal differences and find that a hotter oceanic mantle compared to a colder continental mantle could cause the density contrast accordingly 3 d lithospheric scale gravity models considering temperature dependent mantle densities indicate that the transition between continental and oceanic lithosphere is rather sharp with a steep gradient in thickness beneath the continent ocean transition zone furthermore a mantle wedge of reduced density extends from the oceanic jan mayen fracture zone to the continental jan mayen lineament and points to increased mantle temperatures and or compositional changes beneath the lineament the models further indicate the presence of high density bodies within the lower crust at the continent ocean transition that are continuous with the lowermost oceanic layer 3b in terms of geometry and density this supports the concept of underplated lower crust beneath the western norwegian margin finally ne sw trending linear zones of increased density are required in the lower crust beneath the eastern voring and more basins to fit the short wavelength gravity signal

along strike variations of morphotectonic features in the western foothills of taiwan tectonic implications based on stream gradient and hypsometric analysis abstract the taiwan mountain belt provides a key example for analyzing the relation between morphology and tectonics in an active compressional environment there is a striking geometrical relationship between the location of salients and reentrants of the mountain belt and the presence of major crustal inhomogeneities such as structural highs in the foreland basin major along strike variations of structural styles occur in range front rock units of the fold thrust belt stream gradient and hypsometric analysis has been carried out to highlight the along strike variations of morphotectonic features and to illustrate the relative activities in different tectonic regimes of the western foothills the normalized stream length gradient index sl index and the hack profile are two of the stream gradient indices that effectively reflect the tectonic uplift in a region de trending and residual analysis of the hypsometric integral hi eliminates the spatial dependency of small drainage basins and the residual hypsometric integral corresponds to differential uplift activity integration of stream gradient indices and hypsometry provides more robust tectonic interpretation five morphotectonic provinces have been identified in the western foothills based on stream gradient indices and hypsometry each province is bounded by a series of n140 e trending transfer fault zones either inherited from the eurasian passive margin and or newly formed in the sedimentary cover in response to the presence of basement highs within the foreland basin the peikang and kuanyin highs the morphotectonic features as well as deformation styles vary within each province a high uplift but low shortening rate typifies the crustal deformation style in the transpressional regime north of the peikang basement high on the contrary a low uplift but high shortening rate characterizes the crustal deformation style in the transtensional regime south of the peikang basement high the higher geomorphic indices suggest that greater tectonic activity occurs in central than in southwestern taiwan this inference is also supported by the coseismic deformation of the 1999 chi chi earthquake

frontal part of the northern apennines fold and thrust belt in the romagna marche area italy shallow and deep structural styles in this study surface geological data resulting from a detailed field survey including structural and biostratigraphic analysis have been integrated with subsurface seismic lines and well logs data in order to reconstruct the tectonic evolution of the external zones of the northern italian apennines in the romagna marche foothills and adriatic sea areas this integrated analysis shows 1 a late messinian to lower pleistocene progression of structural development from the hinterland to the foreland of the studied sector of the thrust belt 2 relatively limited 20 southward increasing amounts of shortening obtained by the construction of line length balanced and restored geological cross sections 3 a regional deformation style characterized by the presence of backthrusts associated with most foreland vergent thrust ramps leading to quasi symmetric uplift and a low critical taper for the wedge typical of foreland fold and thrust belts with a weak basal decollement triassic anhydrites in the present case 4 an important influence of basement faulting which despite a general basement cover decoupling appears to control stress localization in the latter producing linkage of basement and cover stuctures in a combination of thin and thick skinned tectonic styles and 5 contrasting structural styles characterizing deep features as imaged by seismic reflection profiles and shallow ones deep stuctures consist of growth anticlines bounded by major thrust ramps and back limb back thrusts separated by broader open synclines both involving a mesozoic paleogene mainly carbonate passive margin succession in the crestal zones of major anticlines shallow structures affecting neogene terrigenous foredeep sediments show a complex pattern of upright to recumbent folds of tens to hundreds of meters wavelength related to minor thrusts and backthrusts deformation of the mesozoic paleogene multilayer appears to be dominated by thrust propagation in the cores of early formed anticlines developed by buckling instabilities the overlying neogene deposits are detached from the carbonate substratum along the base of the foredeep succession bedding parallel slip occurring along this detachment level appears to be accommodated by the complex structures in the crests of major anticlines where the thrusts lramp to the surface cutting up section complex shallow structures interpreted to accommodate at shallow structural levels the deep deformation would therefore represent a geometrical requirement for maintaining strain compatibility across the shallow detachment level located at the base of the foredeep succession

orogen transverse structures in the eastern himalaya dextral riedel shear along the main boundary thrust in the garu gensi area arunachal pradesh india implication in hydrocarbon geoscience abstract structural mapping and analyses reveal deformation in the rocks of the lesser himalayan miri and gondwana and lower siwalik dafla successions across the miri thrust mt and the main boundary thrust mbt in the garu gensi area arunachal himalaya india the north dipping gondwana sequence is sandwiched between the miri group of rocks in the north and the lower siwalik dafla sandstones in the south the gondwana rocks folded four times d1 d4 detail outcrop mapping and structural analyses substantiated by satellite images elucidate that the miri the gondwana and the lower siwalik rock sequences in the area are traversed by two sets of nw and ne trending cross fault zones with 70 100 m thickness mappable for 70 km the cross faults trend nw around the locality daring while in the western part around gensi they trend ne the westernmost fault slipped dextrally and the easternmost one at daring sinistrally these transverse faults offset the mbt 0 52 0 59 km for the western and 0 58 1 41 km for the eastern faults the deformation in the gondwana sequence may be constrained as syn himalayan i e india asia collisional event this was followed by a compression from e ese due to the post eocene indo burmese collision the culminating phase of combined india asia and indo burmese compression is manifested in field with a strong ne directed compression with dextral reidal shear developing in the transverse conjugate fault zones in the area with maximum displacement towards se cluster of the earthquake data indicates record of the events m 6 within 30 80 km depth both n and s of the mbt in the study area further the southerly continuation of the transverse faults below the alluvium can provide vital clue in studying the potential hydrocarbon trap in the northern fringe of the brahmaputra river

identification of possible quaternary deformation in the northeastern mississippi embayment using quantitative geomorphic analysis of drainage basin asymmetry to investigate neotectonism in the mississippi embayment east of the new madrid seismic zone we identified geomorphic domains that show evidence of ground tilting during quaternary time transverse basin profiles were converted to two dimensional vectors that denote channel position with respect to basin divides these basin asymmetry vectors record the net direction and degree of lateral migration of trunk streams more than 2500 vectors were measured and spatially averaged within 400 km 2 bins this field of 300 mean vectors delineates several domains that show preferred directions of stream migrations possibly driven by ground tilting the timing of stream migration was interpreted using across valley distributions of quaternary alluvial terraces comparison of our mean vector field with subsurface structures suggests that some domain boundaries may be related to reactivated faults late quaternary activity is suggested for two northeast striking faults of the southeastern reelfoot rift margin we acquired two seismic profiles showing near surface faulting beneath scarps that follow the domain boundary associated with one of these northeast striking faults big creek fault zone reelfoot thrust seismicity ends on the south against this fault suggesting that the rift margin has dextral slip accommodating northeastward movement of the thrust hanging wall our vector field also suggests late quaternary movement on the reelfoot thrust and on two other northwest striking faults here termed the hatchie river fault and the wolf river fault several other weak domains may imply minor elements of neotectonism our results demonstrate that morphometric analysis of drainage basin asymmetry can be an effective reconnaissance tool within neotectonic settings

the use of the stream length gradient index in morphotectonic analysis of small catchments a case study from central italy abstract the aim of this work is to test an integrated quantitative geomorphic approach based on stream length gradient index sl index analysis within the small catchment of the tarugo river in the northern marchean apennines central italy the tarugo river basin 92 km 2 wide strikes sw ne across the marchean ridge and the western sector of marchean piedmont the area is characterized by a series of nw se trending ne verging thrust folds affecting the meso cenozoic bedrock that pass upward from dominantly carbonate to dominantly terrigenous rocks the area investigated has been affected since the pliocene by extensional tectonics accompanying a regional uplift decreasing in rate north eastwards in this work the sl index analysis has been integrated with the spatial analysis of the amplitude of relief a r and compared to geological and geomorphological field data results of this work indicate that the sl index is a valid tool to detect the long wavelength structural effect on topography as well as the incipient local response to regional processes i e regional uplift that is often undetectable by other morphotectonic parameters in contrast the sl index analysis seems not be a valid tool for discriminating the local lithological influence from the tectonic one

pleistocene glacial terminations triggered by synchronous changes in southern and northern hemisphere insolation the insolation canon hypothesis throughout the last 900 kyr the late pleistocene earth has experienced periods of cold glacial climate punctuated by seven abrupt transitions to warm interglacials the so called terminations although most of glacial ice is located in the northern hemisphere nh the southern hemisphere sh seems to play a crucial role in deglaciation variation in the seasonal distribution of solar insolation is one candidate for the cause of these climatic shifts but so far no simple mechanism has been identified here we present a mathematical analysis of variations in midsummer insolation in both hemispheres at 65 latitude applying this analysis to the entire pleistocene the last 2 myr we find that prior to each termination the insolation in both hemispheres increases in concert with a sh lead introducing time and energy thresholds to these overlaps calculated times for the onsets of the seven terminations by this insolation canon exceptional overlaps meeting the two threshold prerequisites are 23 139 253 345 419 546 and 632 kyr bp perfectly matching the geologic record the timing originates from the interplay between the two orbital parameters obliquity and precession explaining why terminations occur at integer multiple of the precessional cycle there is no such constellation between 1 and 2 myr bp the early pleistocene in agreement with earth s climate at that time this change in orbital forcing coincides with the mid pleistocene revolution separating the late from the early pleistocene therefore we hypothesize that the insolation canon is the trigger for glacial terminations

fission track analysis of the crystalline basement rocks of the calabrian arc southern italy evidence of oligo miocene late orogenic extension and erosion abstract fission track analysis is used to provide low temperature and time constraints on the late orogenic cooling and exhumational history of the crystalline basement rocks of the calabrian arc southern italy 65 samples yielded 57 apatite fission track ages 54 zircon fission track ages and 25 apatite confined fission track length distributions interpretation of this data reveals a phase of increased cooling rates related to exhumation between approximately 35 ma mid oligocene and 15 ma middle miocene evidence from the sedimentary record indicates significant oligo miocene erosion related to this period of exhumation new chronological constraints are also applied to localised late orogenic extensional tectonism that has recently been identified within the basement rocks of the calabrian arc this information is used to produce a new model of the oligo miocene tectonic evolution of the calabrian arc it proposes that the crystalline basement rocks were part of a critical orogenic wedge between the mid oligocene and the middle miocene

accuracy of interpolation techniques for the derivation of digital elevation models in relation to landform types and data density one of the most important scientific challenges of digital elevation modeling is the development of numerical representations of large areas with a high resolution although there have been many studies on the accuracy of interpolation techniques for the generation of digital elevation models dems in relation to landform types and data quantity or density there is still a need to evaluate the performance of these techniques on natural landscapes of differing morphologies and over a large range of scales to perform such an evaluation we investigated a total of six sites three in the mountainous region of northern laos and three in the more gentle landscape of western france with various surface areas from micro plots hillslopes and catchments the techniques used for the interpolation of point height data with density values from 4 to 109 points km2 include inverse distance weighting idw ordinary kriging ok universal kriging uk multiquadratic radial basis function mrbf and regularized spline with tension rst the study sites exhibited coefficients of variation cv of altitude between 12 and 78 and isotropic to anisotropic spatial structures with strengths from weak with a nugget sill ratio of 0 8 to strong 0 01 irrespective of the spatial scales or the variability and spatial structure of altitude few differences existed between the interpolation methods if the sampling density was high although mrbf performed slightly better however at lower sampling densities kriging yielded the best estimations for landscapes with strong spatial structure low cv and low anisotropy while rst yielded the best estimations for landscapes with low cv and weak spatial structure under conditions of high cv strong spatial structure and strong anisotropy idw performed slightly better than the other method the prediction errors in height estimation are discussed in relation to the possible interactions with spatial scale landform types and data density these results indicate that the accuracy of interpolation techniques for dem generation should be tested not only in relation to landform types and data density but also to their applicability to multi scales

crustal uplift in southern england evidence from the river terrace records abstract much of the past work on the quaternary rivers of northwest europe has been concerned with river terraces which characterise almost every valley while these terraces are undoubtedly striking features of the landscape the incision achieved by quaternary rivers is equally significant in terms of river behaviour and for an understanding of the factors affecting landform development during the quaternary this paper examines the incision achieved during the quaternary by the thames in both its upper and lower catchments and by the hampshire avon in southern england valley incision rates of ca 0 07 0 10 m ka 1 have been identified although in the lower catchment of the thames these have been enhanced by additional incision in response to glacio isostasy and valley shortening a model is proposed in which regional uplift is recognized as the primary cause of incision by these quaternary rivers possible mechanisms for regional uplift are considered

morphotectonics and mechanics of the central makran accretionary wedge off pakistan abstract swath bathymetry images and 3 5 khz data acquired during rv sonne cruise 123 in autumn 1997 are the base for analysing the morphology and deformation styles of the huge makran accretionary wedge the continental slope off pakistan is characterised by three morphological provinces a the lower slope is built of a sequence of imbricate thrust slices which form long and narrow accretionary ridges with flanks locally as steep as 20 and between 10 and 20 on average while the regional slope is only 1 2 b the nearly flat mid slope terrace is present in the central east part of the margin narrows significantly towards the east and is absent east of 63 45 and c the upper slope up to the shelf has a regionally uniform slope as steep as about 8 and comprises a very rough topography with many gullies and canyons and evidence for mass wasting two meandering canyons crossing the entire margin down to the abyssal plain at about 63 15 63 30 can be correlated with onshore rivers they have been formed by episodic erosion through turbidity flows and are characterised by erosional and depositional portions sinuosity of the canyons is exclusively caused by the accretionary ridges functioning as obstacles for flow to be directly downhill application of coulomb rheology to the frontal part of the makran wedge implies that the mid level decollement is intrinsically extraordinary weak with a great strength contrast to the overlying sediments comparison with nankai cascadia and the western mediterranean ridge reveals new insights in the parameters controlling the shape of an accretionary wedge and the role of a mid level decollement

quaternary uplift vs tectonic loading a case study from the lucanian apennine southern italy abstract uplift rates have been calculated for a large sector of the lucanian apennine axial zone of the southern apennines italy using both geomorphological observations elevation values ages and arrangement of depositional and erosional landsurfaces and other morpho tectonic indicators and stratigraphical and structural data sea level related facies fault kinematics and offset estimations these data have been compared with those derived from clay mineralogy of mesozoic pelagic successions lagonegro units outcropping in the same sector of the chain which gave information on tectonic loading the values of the quaternary uplift rates of the southern apennines axial zone vary from a minimum of 0 2 mm yr to a maximum of about 1 2 mm yr intermediate values 0 5 0 7 mm yr have been calculated for the other studied areas using geomorphological features and late pliocene to pleistocene successions involved in the genesis of erosional and depositional landsurfaces the same rates 0 6 mm yr have been obtained for a large time span about 2 ma in the melandro basin and adjacent maddalena mts therefore during the last 2 ma the total uplift amount of the axial zone of the lucanian apennine is about 1 2 1 3 km with local peaks of 1 5 km on the other hand the mesozoic pelagic units experienced a tectonic loading of 4 5 km as estimated by means of illite crystallinity in the range 0 6 1 1 2 percentage of illitic layers in illite smectite mixed layers 60 90 and white mica polytypes in the range of 10 35 the quaternary uplift and the related erosion rates of the southern apennines are unquestionably due to strike slip faulting and above all due to extensional tectonics coupled with thermal isostatic regional raising the gap of several kilometres derived from the comparison between uplift rates and tectonic loading values may be explained only by different exhumation modalities starting from late miocene time

analysis of drainage basin symmetry as a rapid technique to identify areas of possible quaternary tilt block tectonics an example from the mississippi embayment there is a coincidence of seismicity and major river valleys in the southwestern mississippi embayment that suggests control of the drainage pattern by northwest trending faults pleistocene river terraces reveal a strong southwestward preferred river migration in this region that may be a result of fault block tilting a rapid new technique of drainage basin analysis is herein presented that quantifies transverse topographic basin symmetry these data permit discrimination of random stream migrations and regionally preferred stream migrations and identify the direction of maximum migration if bedrock dip can be shown to be a negligible influence on stream migration then the direction of regionally preferred migration implies a period of ground tilting in that direction drainage basin asymmetry vectors bearing and degree of asymmetry calculated from transverse topographic profiles of 271 4 km basin segments in the study area suggest preferred stream migration in response to west southwest ward ground tilting bearing 259 the eastward regional dip of bed rock horizons only locally influences migration river terrace distributions reveal a chronology of stream migration episodes southwestward migration in the ouachita saline and arkansas river basins occurred during early to middle pleistocene time in the southwestern mississippi embayment a wisconsin early holocene southwestward migration episode is evidenced along southeast flowing reaches of the ouachita and arkansas rivers but not along the southeast flowing reach of the intervening saline river suggesting that these rivers overlie separate northwest trending tilt blocks although this technique does not provide direct evidence of ground tilting it provides a quick look method of identifying possible tilting elements in neotectonic regions using only topographic maps this technique is of greatest utility where active faults are concealed or poorly exposed such as in the mississippi embayment

geomorphic indicators of active fold growth south mountain oak ridge anticline ventura basin southern california south mountain oak ridge near ventura california is an asymmetric anticlinal uplift forming at the present time above the active buried oak ridge reverse fault shortening along the oak ridge fault accumulated largely in quaternary time and is responsible for the growth and present topography of the westernmost 15 km of the ridge during the past 0 5 m y tectonic geomorphic analysis using several indices of active tectonics provides information concerning fold growth stream gradient indices are relatively high in the northern eroded fold scarp of the ridge a pattern consistent with the existence of active rapid slip on the oak ridge fault mountain front sinuosity along the northern slope of the anticlinal ridge roughly decreases from 2 to 1 toward the westernmost 10 km of observed surface folding valley floor width to valley height ratios along the northern flank of the ridge generally decrease westward from 1 5 to 0 5 values of the hypsometric integral along the northern flank increase significantly from 0 35 to 0 4 maximum 0 55 from east to west drainage density varies from 4 to 6 km km2 along both flanks of the south mountain oak ridge anticline entrenchment of streams into the southern backlimb of the fold along the westernmost 9 km of the structure decreases from 20 m to 1 m from east to west apparent backlimb rotation as measured by dip of strata along the westernmost 7 km of the fold decreases from east to west from 35 to 20 fold growth of the south mountain oak ridge anticline occurred during the past 0 5 ma following deposition of the saugus formation lateral and vertical fold growth were likely produced by westward decrease in fault slip along the buried oak ridge fault

digital terrain modeling abstract this article examines how the methods and data sources used to generate dems and calculate land surface parameters have changed over the past 25 years the primary goal is to describe the state of the art for a typical digital terrain modeling workflow that starts with data capture continues with data preprocessing and dem generation and concludes with the calculation of one or more primary and secondary land surface parameters the article first describes some of ways in which lidar and radar remote sensing technologies have transformed the sources and methods for capturing elevation data it next discusses the need for and various methods that are currently used to preprocess dems along with some of the challenges that confront those who tackle these tasks the bulk of the article describes some of the subtleties involved in calculating the primary land surface parameters that are derived directly from dems without additional inputs and the two sets of secondary land surface parameters that are commonly used to model solar radiation and the accompanying interactions between the land surface and the atmosphere on the one hand and water flow and related surface processes on the other it concludes with a discussion of the various kinds of errors that are embedded in dems how these may be propagated and carried forward in calculating various land surface parameters and the consequences of this state of affairs for the modern terrain analyst

tectonic geomorphology of the san andreas fault zone in the southern indio hills coachella valley california geomorphic investigation of the san andreas fault zone in the indio hills indicates many tectonically produced landforms including beheaded streams right lateral deflected and offset streams sags shutter ridges pressure ridges and fault scarps near biskra palms an alluvial fan pediment complex has an apparent cumulative offset of about 0 7 km along the mission creek fault zone north branch san andreas fault many of the tectonic landforms as well as the fracture pattern that has developed during the pleistocene are explainable by simple shear or uplift associated with a small left bend in the main trace of the mission creek fault the ratio of vertical to horizontal displacement in the vicinity of the bend is about 0 04 exposed in pushawalla canyon 5 km northwest of the alluvial fan pediment complex are 1 a sequence of stream terraces 2 folded plio pleistocene fanglomerates and 3 an example of stream capture following a right lateral deflection or offset of several hundred metres a left step of the mission creek fault in pushawalla canyon is a probably cause of folds and sporadic uplift that produced the stream terraces possible cause of recent stream capture are 1 juxtaposition of pushawalla canyon with a relict canyon moving northwestward along the mission creek fault or 2 right lateral deflection or offset of pushawalla canyon along the fault with simultaneous headward erosion of a shorter steep stream flowing toward the coachella valley estimation of a slip rate and identification of paleoseismicity for the san andreas fault in the indio hills is difficult however degree of topographic dissection formation and preservation of desert pavement and relative soil profile development suggest that the age of the offset fan may be as old as 70 000 yr but that most likely it is on the order of 20 000 to 30 000 yr these age estimates for the offset fan indicate a minimum slip rate for the san andreas fault of 10 to 35 mm yr with about 23 to 35 mm yr the most likely the pattern of observed offset drainages is complex but suggests that during the past few thousand years creep events or moderately large earthquakes have periodically produced several metres of right lateral displacement