the last reconnection of the marmara sea turkey to the world ocean a paleoceanographic and paleoclimatic perspective during the late glacial marine isotope stage 2 the marmara sea transformed into a brackish lake as global sea level fell below the sill in the dardanelles strait a record of the basin s reconnection to the global ocean is preserved in its sediments permitting the extraction of the paleoceanographic and paleoclimatic history of the region the goal of this study is to develop a high resolution record of the lacustrine to marine transition of marmara sea in order to reconstruct regional and global climatic events at a millennial scale for this purpose we mapped the paleoshorelines of marmara sea along the northern eastern and southern shelves at cekmece prince islands and imrali using data from multibeam bathymetry high resolution subbottom profiling chirp and ten sediment cores detailed sedimentologic biostratigraphic foraminifers mollusk diatoms x ray fluorescence geochemical scanning and oxygen and carbon stable isotope analyses correlated to a calibrated radiocarbon chronology provided evidence for cold and dry conditions prior to 15 ka bp warm conditions of the bolling allerod from 15 to 13 ka bp a rapid marine incursion at 12 ka bp still stand of marmara sea and sediment reworking of the paleoshorelines during the younger dryas at 11 5 to 10 5 ka bp and development of strong stratification and influx of nutrients as black sea waters spilled into marmara sea at 9 2 ka bp stable environmental conditions developed in marmara sea after 6 0 ka bp as sea level reached its present shoreline and the basin floors filled with sediments achieving their present configuration

analysis of massif fracturing during deep seated gravitational slope deformation by physical and numerical modeling abstract both 3 d physical modeling and 2 d numerical modeling were used to analyze the development of deep seated gravitational slope deformations we focused especially on the link between fracturing and morphological features such as sagging sackung physical modeling was performed by using properly scaled analogue materials as well as an original vertical accelerator device this device enables cyclic loading of the model and to advance step by step in the deformation process this technique is thus particularly well suited to analyze rupture initiation and evolution surface deformation is registered with a high resolution digital camera internal model deformation was studied by making cross sections at different experiment stages the failure of one or both mountain sides was observed with a deep seated failure zone that follows an almost circular trajectory it intersects the surface perpendicularly in the upper part other fractures are generated in the moving mass in response to its motion fracture network becomes wider and morphological features such as counterscarps are generated numerical models were performed with a 2 d finite element code named adeli we tried to reproduce physical modeling results by using the same mechanical behaviour and parameters of the analogue material the results reproduced failure initiation well but poorly described moving mass deformation furthermore rupture initiation in the 2 d numerical models occurs more easily e g for a lower acceleration value than in the 3 d physical models confirming the importance of the three dimensional analysis

long term gravitational deformation of rocks by mass rock creep abstract subsurface rocks beneath slopes are deformed to various degrees in various ways by mass rock creep mrc when they are subjected to a gravitationally unstable state for a long period mrc forms folds faults and numerous kinds of fractures such deformation is one of the main factors for deteriorating rock masses on slopes and also precursors of many landslides mrc deformations which have often been ascribed to tectonic origins can be distinguished from tectonic ones by their deformational features landforms and relationships between slope morphology and subsurface structures mrc folds are flexural slip folds that have the following mesoscopic to microscopic characteristics their axial surfaces are not smooth but are jagged and many visible openings or open fractures develop in association with the folds the jagged axial surfaces become smoother at depth and openings decrease in width with increasing overburden at the deformation site macroscopic types of mrc folds change according to the relationship between foliations and slopes buckling folds form in consequent slopes drag folds form in a deeper part of obsequent slopes and bending folds form in slopes with steep dipping foliations consequent or obsequent by downslope bowing of foliations shear fractures and tension fractures are the main deformational structures formed by mrc in massive rocks among shear fractures those of listric origin are remarkable tension fractures in general occur either in networks dividing rocks into fragments that slip and rotate irregularly in relation to each other or in parallel arrays of steeply dipping fractures an mrc fault has a shear zone consisting of a pulverized zone with gouge and a phyllitic or brecciated zone in a densely foliated rock the phyllitic zone is formed by microscopic slip along foliations in a sparsely foliated rock the brecciated zone is formed by random crushing except for the faults made through the shear fractures in massive rocks landforms due to mrc are gentle slopes bounded by horseshoe knicklines upslope convex slopes ridge top depressions multiple ridges uphill facing scarps and ridge crossing depressions

late glacial holocene palaeoceanography of the sea of marmara timing of connections with the mediterranean and the black seas abstract stratigraphic analysis of late quaternary sediments of the sea of marmara basin smb indicates that it was a freshwater lake during the late glacial to ca 12 000 yr bp depositing sediments with a neoeuxinian fauna characteristic of the black sea basin at ca 12 000 yr bp it was inundated by the mediterranean waters and gradually converted into a marine realm as indicated by the presence above the neoeuxinian sediments of a mixed layer containing both marine and freshwater fauna a sapropelic sediment layer was deposited between 10 600 and 6400 yr bp under suboxic bottom water conditions this layer roughly corresponds in time to s1 sapropel unit of the eastern mediterranean suggesting a common origin its presence in the smb therefore supports the hypothesis that a large influx of freshwaters from the black sea was an important factor in sapropel formation in the eastern mediterranean a second sapropelic layer formed in the smb during 4750 to 3200 yr bp the earliest known record of mediterranean water in the bosphorus is at ca 5300 yr bp suggesting a later marine inundation than the 7150 yr bp event suggested by ryan and co workers an abrupt drowning of black sea shelf at 7 5 kyr bp geo eco marina 2 proc int workshop on fluvial marine interactions mainas romania 1 7 october 1997 pp 115 125 and ryan w b f pitman iii w c major c o shimkus k moskalenko v jones j a dimitrov p gorur n sakinc m yuce h 1997b an abrupt drowning of black sea shelf mar geol 138 1997 119 126 this implies that either earlier marine connections with the black sea were through a different waterway or the earlier marine record in the strait has been eroded the present two layer flow system was established at 4000 yr bp

mars and earth comparison of cold climate features abstract on earth glacial and periglacial features are common in areas of cold climate on mars the temperature of the present day surface is appropriate for permafrost and the presence of water is suspected from data relating to the outgassing of the planet from remote sensing measurements over the polar caps and elsewhere on the martian surface and from recognition of fluvial morphological features such as channels these observations and the possibility that ice could be in equilibrium with the atmosphere in the high latitudes north and south of 40 latitude suggest that glacial and periglacial features should exist on the planet morphological studies based mainly on viking pictures indicate many features that can be attributed to the action of ice among these features are extensive talus aprons debris avalanches flows that resemble glaciers or rock glaciers ridges that look like moraines various types of patterned ground scalloped scarps and chaotically collapsed terrain that could be attributed to thermokarst processes and landforms that may reflect the interaction of volcanism and ice

deglacial sea level record from tahiti corals and the timing of global meltwater discharge the timing of the last deglaciation is important to our understanding of the dynamics of large ice sheets1 and their effects on the earth s surface2 3 moreover the disappearance of the glacial ice sheets was responsible for dramatic increases in freshwater fluxes to the oceans which probably disturbed the ocean s thermohaline circulation and hence global climate4 7 sea level increases bear witness to the melting of continental ice sheets but only two such records from barbados8 9 and new guinea10 11 corals have been accurately dated but these corals overlie active subduction zones where tectonic movements are large and often discontinuous especially in new guinea so the apparent sea level records may be contaminated by a complex tectonic component here we date fossil corals from tahiti which is far from plate boundaries and thus is likely to be tectonically relatively stable and remote from the locations of large former ice sheets the resulting record indicates a large sea level jump shortly before 13 800 calendar years bp which corresponds to meltwater pulse 1a in the barbados coral records8 9 the timing of this event is more accurately constrained in the tahiti record revealing that the meltwater pulse coincides with a short and intense climate cooling event12 15 that followed the initiation of the bolling allerod warm period12 16 but preceded the younger dryas cold event by about 1 000 years

the initiation and growth of en echelon veins abstract numerical models are used to understand the evolution of mode i opening fractures from spatially random distributions in a brittle elastic material en echelon arrays commonly develop because mechanical fracture interaction promotes growth for this geometry this provides a new mechanism for en echelon vein formation in rock which is distinctly different than previously proposed mechanisms it is suggested that some macroscopic en echelon vein arrays may have served as zones of weakness that localized later shear zone development in a manner analogous to that observed by experimentalists examining micro cracking and subsequent shear rupture of rocks loaded under compression sigmoidally shaped veins and vein fillings are explicitly modeled showing that they can form in response to the mechanical interaction of neighboring fractures which redirects the propagation path numerical comparison of sigmoidal veins formed by brittle fracture and by ductile shear zones demonstrates some of the pitfalls of failing to correctly identify the mechanism of formation

an abrupt drowning of the black sea shelf abstract during latest quaternary glaciation the black sea became a giant freshwater lake the surface of this lake drew down to levels more than 100 m below its outlet when the mediterranean rose to the bosporus sill at 7 150 yr bp 1 saltwater poured through this spillway to refill the lake and submerge catastrophically more than 100 000 km2 of its exposed continental shelf the permanent drowning of a vast terrestrial landscape may possibly have accelerated the dispersal of early neolithic foragers and farmers into the interior of europe at that time

martian polar and circum polar sulfate bearing deposits sublimation tills derived from the north polar cap previous spectroscopic studies have shown the presence of hydrated minerals in various kinds of sedimentary accumulations covering and encircling the martian north polar cap more specifically gypsum a hydrated calcium sulfate has been detected on olympia planum a restricted part of the circum polar dune field to further constrain the geographical distribution and the process of formation and accumulation of these hydrated minerals we performed an integrated morphological structural and compositional analysis of a key area where hydrated minerals were detected and where the main polar landforms are present by the development of a spectral processing method based on spectral derivation and by the acquisition of laboratory spectra of gypsum ice mixtures we find that gypsum bearing sediment is not restricted to the olympia planum dunes but is also present in all kinds of superficial sediment covering the surface of the north polar cap and the circum polar dune field spectral signatures consistent with perchlorates are also detected on these deposits the interpretation of landforms reveals that this gypsum bearing sediment was released from the ice cap by sublimation we thus infer that gypsum crystals that are now present in the circum polar dune field derive from the interior of the north polar cap gypsum crystals that were initially trapped in the ice cap have been released by sublimation of the ice and have accumulated in the form of ablation tills at the surface of the ice cap these gypsum bearing sublimation tills are reworked by winds and are transported towards the circum polar dune field comparison with sulfates found in terrestrial glaciers suggests that gypsum crystals in the martian north polar cap have formed by weathering of dust particles either in the atmosphere prior to their deposition during the formation of the ice cap and or in the ice cap after their deposition

deformation of high slopes in different rocks after wurmian deglaciation in the gailtal austria abstract in the southern part of the eastern alps extended mass movements in different rocks are described in a sequence of crystalline rocks mainly mica schists and phyllonite and sediments sandstone siltstone and limestones various types of mass movements due to mechanical properties of the rocks occurred therefore a great scale bending along with rotational gliding and toppling of the bigger blocks can be recognized in the mica schists in the major parts of the slopes this slope failure leads to a complete disintegration of structures in the phyllonites in the sedimentary part of the sequence the brittle limestone as the competent part failed above the soft incompetent base the main reason for this mostly active deformation of the slopes is glacial erosion causing overdeepened valleys and steep slopes especially active parts are caused by strong river erosion all these phenomena are temporarily closely related to the development of the glaciers

late holocene deep sea benthic foraminifera from the sea of marmara abstract the benthic foraminiferal assemblages of two cores from the late holocene organic carbon rich and carbonate poor deep sea sediments of the eastern depression of the sea of marmara have been studied they were deposited under high level of primary productivity and poorly oxygenated bottom water conditions they show low diversity and are dominated by a group of species adapted to an infaunal life style with wide bathymetric distribution ca 70 2000 m in the mediterranean sea oxygen deficiency down to about 0 5 ml l does not seem adversely to affect the rate of reproduction of the dominant species belonging to melonis chilostomella buliminids and bolivinitids their distribution is primarily controlled by substrate conditions faunal similarities with fossil assemblages in association with some late quaternary sapropels and related facies from the eastern mediterranean basins suggest that they were deposited under palaeo oceanographic conditions closely similar to those of the modern sea of marmara

ferric oxides in east candor chasma valles marineris mars inferred from analysis of omega mars express data identification and geological interpretation 1 the mineralogical composition of the martian surface is constrained by analyzing the data of the omega visible and near infrared imaging spectrometer onboard mars express ferric signatures had previously been reported in valles marineris margaritifer terra and terra meridiani here we use three independent data reduction methods spectral angle mapper a modified spectral mixture analysis and modified gaussian model to detect and map ferric oxides in east candor chasma a part of valles marineris ferric oxides in east candor chasma are concentrated in scattered formations mola altimetry indicates that the ferric oxides are preferentially located in topographic lows themis hrsc and moc images show that the ferric oxide spectral signatures are systematically correlated with superficial deposits of low albedo located at the foot of or resting on interior layered deposits ilds this spatial distribution suggests that ferric oxides are genetically linked to ilds gravity and wind driven remobilization of ferric oxides previously formed in the ilds can explain their accumulation around the ilds

hydrated mineral stratigraphy of ius chasma valles marineris new high resolution spectral and morphologic imaging of deposits on walls and floor of ius chasma extend previous geomorphic mapping and permit a new interpretation of aqueous processes that occurred during the development of valles marineris we identify hydrated mineralogy based on visible near infrared vnir absorptions we map the extents of these units with crism spectral data as well as morphologies in ctx and hirise imagery three cross sections across ius chasma illustrate the interpreted mineral stratigraphy multiple episodes formed and transported hydrated minerals within ius chasma polyhydrated sulfate and kieserite are found within a closed basin at the lowest elevations in the chasma they may have been precipitates in a closed basin or diagenetically altered after deposition fluvial or aeolian processes then deposited layered fe mg smectite and hydrated silicate on the chasma floor postdating the sulfates the smectite apparently was weathered out of noachian age wallrock and transported to the depositional sites the overlying hydrated silicate is interpreted to be an acid leached phyllosilicate transformed from the underlying smectite unit or a smectite jarosite mixture the finely layered smectite and massive hydrated silicate units have an erosional unconformity between them that marks a change in surface water chemistry landslides transported large blocks of wallrock some altered to contain fe mg smectite to the chasma floor after the last episode of normal faulting and subsequent landslides opal was transported short distances into the chasma from a few m thick light toned layer near the top of the wallrock by sapping channels in louros valles alternatively the material was transported into the chasma and then altered to opal the superposition of different types of hydrated minerals and the different fluvial morphologies of the units containing them indicate sequential distinct aqueous environments characterized by alkaline then circum neutral and finally very acidic surface or groundwater chemistry

paleomagnetic poles of mars revisited 1 the huge amount of data acquired by mars global surveyor during its mapping period provides a unique opportunity to reassess the paleomagnetic pole positions of mars previously determined on the basis of the limited low altitude magnetic data we identify nine small and isolated magnetic anomalies on the basis of the global magnetic maps and model each anomaly using a vertical prism of elliptical cross section both high altitude 360 430 km and low altitude 100 200 km magnetic data are used simultaneously we calculate a paleomagnetic pole position assuming that the body is magnetized by a dipole core field although the new pole positions do not cluster as closely as the old ones the new cluster overlaps the older cluster the clustering suggests that mars rotation axis has likely wandered by 50 60 in the last 4 gyr the number of north and south poles in the cluster suggests at least one reversal of the core field during the time the source bodies acquired magnetization

paleoenvironments of the marmara sea turkey coasts from paleontological and sedimentological data abstract the faunal composition of upper pleistocene holocene sedimentary sections was investigated from several boreholes in the coastal areas of the northern and eastern marmara sea the boreholes penetrated to pre quaternary basement and contain sediments deposited in near shore environments such as lagoons estuaries and deltas during the post glacial transgression rapidly rising sea level drowned these littoral areas progressively transforming into their present form over the last 9 5 10 ka bp uncalib thus the lower kucukcekmece valley became a lagoon while the golden horn became an estuary on the northeast coast the kurbagali delta was submerged when the rate of sea level rise decreased at about 5000 6000 years ago the influence of mediterranean water on the faunal assemblage was surpassed by salinity tolerant forms probably due to increased freshwater and sediment input on land

a review of possible eustatic isostatic and tectonic contributions in eight late holocene relative sea level histories from the mediterranean area abstract this paper consists of a comparison between eight late holocene sea level histories investigated by the author in different mediterranean areas and sea level predictions in the same areas made by global isostatic models the areas include three regions that are generally considered as tectonically relatively stable 1 the southern coast of france 2 sardinia and 3 the southern coasts of tunisia where late holocene evidence may be either of submergence or of emergence also considered are 4 a subsidence region in the northern adriatic and actively uplifting areas 5 in calabria and 6 in nisyros island greece lastly case studies in areas affected by repeated coseismic vertical displacements include 7 western crete and antikythira island in the hellenic arc and 8 the levant coasts of turkey syria and the lebanon in each case the question of whether the evidence available may or may not be consistent with gradual isostatic or eustatic displacements has been explored it appears that in non tectonic areas the hydro isostatic effects have been overestimated sardinia or underestimated southern tunisia by the same models in the northern adriatic the closest mediterranean area to the former scandinavian ice sheet glacio eustatic effects are suspected to be almost absent our analysis failed to quantify isostatic effects in areas of rapid tectonic uplift calabria and nisyros but rejected predictions of significant isostatic subsidence in the hellenic arc and on the levant coast finally several data from tectonic and non tectonic areas are consistent with nearly stable global eustasy since 6000 bp thus challenging the assertion of significant additional melting of antarctica after the complete melting of the former northern hemisphere ice caps

ancient groundwater flow in the valles marineris on mars inferred from fault trace ridges long linear ridges in the valles marineris region of mars most likely represent fault zones that have been cemented by water deposited minerals this implies that water in the martian crust could have traversed long distances via faults and fractures

controls on the failure mode of brittle inclusions hosted in a ductile matrix plane strain deformation experiments were performed on elliptical inclusions of cohesive sand embedded within a slab of pitch with the aim of investigating the mode of fracturing of brittle inclusions within a ductile matrix under pure and simple shear the inclusions failed in three different modes tensile fracturing mode 1 shear fracturing mode 2a and extensional shear fracturing mode 2b jeffrey s 1922 theory of the flow of a viscous medium around an ellipsoidal body was applied to the experimental results to determine the principal tensile and compressive stresses within an inclusion and analyze the failure modes using griffith s criterion the analysis reveals that the aspect ratio r and the orientation u of the inclusion control the principal tensile and compressive stresses within it and in turn govern the mode of brittle deformation at a particular inclusion orientation the tensile stress increases whereas the compressive stress decreases monotonically with increasing aspect ratio of the inclusion the principal stresses also vary with inclusion orientation for a given aspect ratio but not monotonically the analysis delimits the fields of each mode of brittle deformation of inclusions in r u space under pure shear and simple shear q 2001 elsevier science ltd all rights reserved

extent and basal characteristics of the m clintock channel ice stream abstract the m clintock channel palaeo ice stream drained the northwestern margin victoria island arctic canada of the laurentide ice sheet functioning for 200 years prior to 10 ka bp from its bed imprint it is reconstructed as 720 140 km with a cross sectional area of 100 km2 comparable in size to the hudson strait ice stream it drained an estimated 80 000 km3 of ice enough to significantly affect the shrinking ice sheet and drive the keewatin ice divide south eastwards such discharges likely produced heinrich events and influenced the temperature and salinity of the western arctic ocean ice stream location was controlled by a topographic trough but glaciological regulation rather than properties of the bed controlled margin locations and hence ice stream width the ice stream eroded into pre existing unconsolidated sediments and left a pattern of subglacially produced landforms recording a snapshot view of the bed prior to shutdown frictional shutdown occurred once downcutting through sediments reached bedrock in places high sediment availability appears critical for ice stream functioning with a drift thickness of 50 m required to sustain its 200 year lifespan debris discharge was exceptionally high 73 000 m3 a 1 m 1 this ice stream demonstrates non steady response of ice sheets to climate change and their large impact on mass balance and stability of ice sheets

clay mineral distribution in last glacial holocene sediment cores from the eastern marmara sea cinarcik basin izmit gulf transition nw turkey multisources and transport paths in a two way flow system abstract the regional variations in grain size xrd bulk and clay mineral distribution in 97 sediment samples from 6 gravity cores obtained from 20 to 300 m water depths have been investigated to reveal source and transportation patterns as well as the effects of climatic and sea level changes during the last 25 000 14 c bp in the eastern marmara sea ems nw turkey the major proportions of sediments in the ems consist of silt 20 83 and clay 17 90 whereas sand and gravel abundances rarely exceed 10 of the bulk minerals 10 a micas 23 55 and feldspars 17 55 dominate over quartz 10 21 and calcite 10 26 smectites 23 62 illite 18 36 chlorites 6 21 kaolinite 2 20 and 14s 14c mixed layer minerals 0 27 constitute the principal clay mineral assemblages both bulk and clay mineral assemblages in the ems are similar to those found in the izmit gulf on the southern marmara shelf at the marmara aegean approaches and the southern black sea this would suggest that there is no distinct source for mineral assemblages of the study area outside the marmara basin the concentrations of clay fractions and clay mineral assemblages tend to increase or decrease with depth in the cores but this is limited to some intervals and not to entire sections in the cores this distribution pattern therefore represents rather local sources of provenance and surrounding fluvial drainage basins together with dilution and distribution effects by current transport processes rather than the expected paleoclimatic features and sedimentary input by inflowing black sea and aegean sea water masses throughout the last glacial to holocene

morphology evolution and tectonics of valles marineris wallslopes mars abstract hillslopes up to 11 km in height can be found along the walls of the valles marineris troughs the widest and deepest troughs are grabens in which tectonics probably exerted the primary control on the wall morphology geographical variations in the wall morphology and profiles show that they result from complex persistent tectonic influences and that significant changes in erosional processes occurred during this evolution from late hesperian to late amazonian preliminary calculations suggest that about 85 95 of the fault controlled wall relief probably formed in an ancient stage prior to this transitional period a study of the volatile content of the wall rocks based upon the morphology and distribution of impact craters on the surrounding plateaus shows that extreme erosional widening of the central valles marineris troughs occurred during the ancient stage of high ground ice content during the subsequent recent stage of tectonic and morphological evolution the wall materials were partly desiccated

cosmogenic 10be dating of a sackung and its faulted rock glaciers in the alps of savoy france sackungs are the largest gravitational deformation observed in mountains they are characterized by the long term slowness of the movements but their mechanism is still not well understood nowadays cosmic ray exposure cre dating methods allow dating the morphologic structures involved in sackung and can contribute at the understanding of their origin in the alps the 5 3 km long arcs sackung initiated during the activity of rock glaciers three samples from these faulted rock glaciers provide their first cre ages and show that at 2000 m elevation these block accumulations moved during the younger dryas and stopped in early holocene six 10be ages of fault scarps show that the arcs sackung lasted only a few thousand years and stopped at about 8462 432 10be yr they also reveal that deformation migrated upslope in agreement with a mechanism of flexural toppling of vertical layers this unique and long gravitational event characterized by migration of the deformation does not support earthquake shaking as triggering mechanism for individual faults it shows that in the upper isere valley slope deformation was delayed of several thousand years after glacial debuttressing and is not anymore active despite its fresh morphology

oscillating quaternary water levels of the marmara sea and vigorous outflow into the aegean sea from the marmara sea black sea drainage corridor abstract detailed interpretation of single channel air gun and deep tow boomer profiles demonstrates that the marmara sea turkey experienced small amplitude 70 m fluctuations in sea level during the later quaternary limited in magnitude by the sill depth of the strait of dardanelles moderate subsidence along the southern shelf and quaternary glacio eustatic sea level variations created several stacked deltaic successions separated by major shelf crossing unconformities which developed during the transitions from global glacial to interglacial periods near the strait of dardanelles a series of sand prone deposits are identified beneath an uppermost holocene transparent mud drape the sandy deposits thicken into mounds with the morphology and cross sectional geometries of barrier islands sand waves and current generated marine bars all cross stratification indicates unidirectional flow towards the dardanelles prior to the deposition of the transparent drape which began 7000 years bp in strong support of the notion that the marmara sea flowed westwards into the aegean sea through the dardanelles at times of deglaciation in northern europe the global sea level curve shows that at 11 000 and 9500 years bp sea level rose to the sill depths of the straits of dardanelles and bosphorus respectively the effect from 11 000 to 9500 years bp was seawater incursion into the marmara sea drowning and formation of algal serpulid bioherms atop lowstand barrier islands and transgression of shelves and lowstand deltas at 9500 years bp glacial meltwater temporarily stored in the black sea lake developed into a vigorous southward flow toward the aegean sea forming west directed sandy bedforms in the western marmara sea and initiating deposition of sapropel s1 in the aegean sea this strong outflow persisted until 7000 years bp after which a mud drape began to accumulate in the marmara sea and euryhaline mediterranean mollusks successfully migrated into a progressively more saline black sea where sapropel deposition began most eastern mediterranean sapropels from s1 to s11 appear to correlate with periods of rising sea level and breaching or near breaching of the bosphorus sill these events are believed to coincide with times of vigorous outflow of low salinity fresh surface waters transiting the black sea marmara sea corridor and ultimately derived from melting of northern european ice sheets

equatorial glaciations on mars revealed by gravitational collapse of valles marineris wallslopes abstract martian global climate models that account for evidence of past glaciations reported in tropical to mid latitude regions of mars predict accumulation of water ice in valles marineris during past periods of high obliquity observational evidence for such glaciations is given here topographic basement ridges of tectonic origin are common in valles marineris and display sackung features an assemblage of tectonic patterns that are diagnostic of deep seated gravitational slope deformation this deformation is most easily explained by paraglacial ridge failure subsequent to ridge wall debuttressing and decohesion following the retreat of glaciers this interpretation is supported by extensive bibliographic analysis of sackung triggers on earth by morphological evidence of subglacial erosion of the lower parts of valles marineris wallslopes of periglacial erosion of their upper parts and by the presence of various types of glacial landforms on the floors of valles marineris troughs the age of these equatorial glaciations is found to be older than 1 4 gy and younger than 3 5 gy

relative age of interior layered deposits in southwest candor chasma based on high resolution structural mapping high resolution topography generated from stereo hirise high resolution imaging science experiment imagery reveals the meter scale structure of interior layered deposits ild in southwest candor chasma this study seeks to determine the age of the local ild relative to any normal faults that can be attributed to chasma formation the study area is located near the contact of these ild and the wall rock and is in an area where chasma forming normal faults have been proposed we find that while normal faults are found in the study area these faults are not sufficiently large nor appropriately located or oriented to accommodate the roughly northeast southwest extension that is required for normal faults that can be attributed to chasma formation additionally bedding exposed in the local ild generally dips toward the center of candor chasma consistent with sediment deposition in a preexisting basin further pit craters of tithonia catena presumed to predate or be contemporaneous with the formation of west candor chasma do not cut into the ild within the study area these independent lines of evidence support a postchasma age for the ild exposed within the study area chasma related normal faults may exist within these ild at depth but are not exposed at the surface approximately 2 km of conformable stratigraphy is exposed in the study area and therefore at least several kilometers of the local ild were deposited subsequent to any chasma related normal faulting that may have occurred in this part of candor chasma

a short note on the geo archeological significance of the ancient theodosius harbour istanbul turkey abstract the sedimentary sequence discovered at archaeological excavations in ancient theodosius harbour at istanbul contains the records of sea level environmental changes and the cultural history of the region the cobbles at the base of the sequence include archaeological remnants of neolithic culture that settled in the area between 8 4 and 7 3 14c ka bp and are located at 6 m below the present sea level the sediments representing a coastal environment indicate that the area was used as a harbour from ad 4th to at least the 11th century and were filled by the sediments derived from lykos stream after 11th century

controlled moraines origins characteristics and palaeoglaciological implications abstract controlled moraines are supraglacial debris concentrations that become hummocky moraine upon de icing and possess clear linearity due to the inheritance of the former pattern of debris rich folia in the parent ice linearity is most striking wherever glacier ice cores still exist but it increasingly deteriorates with progressive melt out as a result moraine linearity has a low preservation potential in deglaciated terrains but hummocky moraine tracts previously interpreted as evidence of areal stagnation may instead record receding polythermal glacier margins in which debris rich ice was concentrated in frozen toe zones recent applications of modern glaciological analogues to palaeoglaciological reconstructions have implied that a controlled moraine development can be ascribed to a specific process e g englacial thrusting or supercooling and b controlled moraine preservation potential is good enough to imply the occurrence of the specific process in former glacier snouts e g ancient polythermal or supercooled snouts these assumptions are tested using case studies of controlled moraine construction in which a wide range of debris entrainment and debris rich ice thickening mechanisms are seen to produce the same geomorphic features polythermal conditions are crucial to the concentration of supraglacial debris and controlled moraines in glacier snouts via processes that are most effective at the glacier permafrost interface end moraines lie on a process form continuum constrained by basal thermal regime the morphological expression of englacial structures in controlled moraine ridges is most striking while the moraines retain ice cores but the final deposits landforms tend to consist of discontinuous transverse ridges with intervening hummocks preserving only a weak impression of the former englacial structure these are arranged in arcuate zones of hummocky moraine up to 2 km wide containing ice walled lake plains and lying down flow of streamlined landforms produced by warm based ice a variety of debris entrainment mechanisms can produce the same geomorphic signature spatial and temporal variability in process form relationships will lead to the sequential development of different types of end moraines during the recession of a glacier or ice sheet margin

slope instability in relation to glacial debuttressing in alpine areas upper durance catchment southeastern france evidence from field data and 10be cosmic ray exposure ages the upper durance catchment is an area prone to rock slope failures such failures reflect the combination of high relief litho structural controls and paraglacial stress release the aim of this study is to determine the role of deglacial unloading and resulting paraglacial stress release in conditioning or triggering slope failure former dimensions of the durance glacier are reconstructed then combined with digital elevation model data in a raster geographic information system to quantify the spatial pattern of stresses associated with glacial loading at the last glacial maximum preliminary calculations suggest that major rock falls and rock avalanches are associated with areas subject to the highest decompression stresses focus on two case studies allows the consequences of paraglacial stress release on slope instability to be evaluated description of slope failure runout deposits allows reconstruction of the nature of slope failure surface exposure dates based on concentration of cosmogenic 10be allows the timing of both deglaciation and that of post glacial rock slope failures to be established it is shown that rock slope failures are concentrated on lower valley side slopes within the area occupied by ice at the last glacial maximum and that their locations coincide with zones of inferred high glacial loading stress consistent with interpretation of both bedrock disruption and large scale rock slope failures as paraglacial phenomena induced by stress release following deglaciation timing of initial rock avalanche runout deposition at one site is consistent with this conclusion though later instability episodes at the same site may have occurred independent of the influence of paraglacial stress release

holocene coastal change in the ancient harbor of yenikapi istanbul and its impact on cultural history an extensive rescue excavation has been conducted in the ancient harbor of istanbul yenikapi by the sea of marmara revealing a depositional sequence displaying clear evidence of transgression and coastal progradation during the holocene the basal layer of this sequence lies at 6 m below the present sea level and contains remains of a neolithic settlement known to have been present in the area indicating that the sea level at 8 9 cal ka bp was lower than 6 m below present sea level advanced to its maximum at 6 8 7 cal ka bp drowning lykos stream and forming an inlet at its mouth after 3 cal ka bp coastal progradation became evident subsequent construction of the byzantine harbor theodosius 4th century ad created a restricted small basin and accumulation of fine grained sediments the sedimentation rate was increased due to coastal progradation and anthropogenic factors during the deposition of coarse grained sediments at the upper parts of the sequence 7th 9th centuries ad the harbor was probably abandoned after the 11th century ad by filling up with lykos stream detritus and continued seaward migration of the coastline

last glacial holocene paleoceanography of the black sea and marmara sea stable isotopic foraminiferal and coccolith evidence multi proxy data and radiocarbon dates from several key cores from the black sea and marmara sea document a complex paleoceanographic history for the last v30 000 yr the marmara sea was isolated from both the black sea and the aegean sea during glacial periods when global sea level lowering subaerially exposed the shallow sills at the straits of bosphorus and dardanelles i e lake stage and reconnected through both straits during interglacial periods when rise of global sea level breached the shallow sills i e gateway stage micropaleontological data show that during the lake stage the surface water masses in both the marmara sea and black sea became notably brackish however during the gateway stages there was a low salinity surface layer and normal marine water mass beneath two sapropel layers are identified in the marmara sea cores sapropels m2 and m1 were deposited between v29 5 and 23 5 ka and v10 5 and 6 0 ka respectively micropaleontological and stable isotopic data show that the surface water salinities were reduced considerably during the deposition of both sapropel layers m2 and m1 and calculation using planktonic foraminiferal transfer functions shows that sea surface temperatures were notably lower during these intervals the presence of fauna and flora with black sea affinities and the absence of mediterranean fauna and flora in sapropels m1 and m2 strongly suggest that communication existed with the black sea during these times a benthic foraminiferal oxygen index shows that the onset of suboxic conditions in the marmara sea rapidly followed the establishment of fully marine conditions at v11 10 5 ka and are attributed to black sea outflow into the marmara sea since 10 5 ka these suboxic conditions have persisted to the present the data discussed in this paper are completely at odds with the flood hypothesis of ryan et al 1997 and ryan and pitman 1999 crown copyright 2002 elsevier science b v all rights reserved

fault growth by linkage observations and implications from analogue models abstract using time sequence analyses of extensional fault models we demonstrate the pivotal role played by fault segmentation in the accumulation of displacement and length during the growth of faults experiments are described in which incremental steps during the development of individual faults have been reconstructed from time lapse photographs taken during model deformation these records confirm the composite segment hierarchy of fault structure a pattern that is frequently recognised in many natural arrays they reveal the progressive enlargement of individual faults to be the product of a repetitive cycle of tip line propagation overlap and linkage between nearest neighbours by contrasting the displacement patterns of successive increments during growth convincing evidence is also presented to suggest that individual segments of faults may remain kinematically independent once they are physically linked this behaviour is shown to be responsible for the characteristic saw tooth patterns often recognised in strike parallel fault displacement profiles such patterns are believed to arise where relict segment boundaries remain preserved as asperities to slip so that displacement is confined to discrete parts of a fault plane surface growth in this way also causes the maximum displacement d and surface length l of faults to continually change by different proportions incremental displacement records presented here corroborate field evidence which shows that linkage between fault segments during growth is responsible for a significant component of the spread of values often recorded in d versus l compilations finally we speculate that linkage between fault segments also accounts for transient irregularities recorded in the frequency distribution of the fault length populations of each model

sulfates and iron oxides in ophir chasma mars based on omega and crism observations abstract we investigate the sulfate and iron oxide deposits in ophir chasma mars based on short wave infrared data from the compact reconnaissance imaging spectrometer for mars crism and from the observatoire pour la mineralogie l eau les glaces et l activite omega sulfates are detected mainly in two locations in the valley between ophir mensa and the southern wall of ophir chasma kieserite is found both within the slope of ophir mensa and superposed on the basaltic wall of the chasm here kieserite is unconformably overlain by polyhydrated sulfate deposits and iron oxides locally jarosite and unidentified phases with absorptions at 2 21 m or 2 23 m are detected which could be mixtures of jarosite and amorphous silica or other poorly crystalline phases the second large sulfate rich outcrop is found on the floor of the central valley although the same minerals are found here polyhydrated sulfates kieserite iron oxides and locally a possibly jarosite bearing phase this deposit is very distinct it is not layered almost horizontal and located at a much lower elevation of below 4250 m kieserite superposes polyhydrated sulfate rich deposits and iron oxides form lags the facies of sulfate formation remains unclear and could be different for the two locations a formation in a lake playa or under a glacier is consistent with the mineralogy of the central valley and its flat low lying topography this is not conceivable for the kieserite deposits observed south of ophir mensa these deposits are observed over several thousands of meters of elevation which would require a standing body of water several thousands of meters deep this would have lead to much more pervasive sulfate deposits than observed these deposits are therefore more consistent with evaporation of groundwater infiltrating into previously sulfate free light toned deposits the overlying polyhydrated sulfates and other mineral phases are observed in outcrops on ridges along the slopes of the southern chasm wall which are too exposed to be reached by groundwater here a water supply from the atmosphere by rain snow fog or frost is more conceivable

geological context of water altered minerals in valles marineris mars 1 greater than 15 000 km2 of the layered deposits within valles marineris are associated with water altered minerals yet their origin and history of alteration remain a mystery there are numerous competing hypotheses for the formation of the interior layered deposits including aeolian lacustrine and volcanic recent orbiter spectroscopic data have indicated that water has played a role in their geological history thermal emission spectrometer tes measurements have revealed significant crystalline hematite bearing deposits within valles marineris typically related to interior layered deposits these hematite deposits found with a wide range of albedo values are associated with relatively steep bedrock exposures but can also be seen downslope on flat surfaces where they may be a lag deposit more recently observatoire la mineralogie l eau les glaces et l activite omega data have shown hydrated sulfates covering more than 13 000 km2 area of valles marineris sulfates are found in numerous topographic settings and geological units but are typically located along the flanks of interior layered deposits and nearby low lying floor units here we study the detailed morphologies of hematite and sulfate bearing units such as mantled wall units mass wasting blocky deposits massive floor deposits and tectonically altered floor units all of these terrains have diverse erosional styles and varied crater populations in both hematite and sulfate bearing units occasionally found in conjunction with one another formation processes require contributions from water the results indicate a wide range of diversity within an individual mineral class between mineral classes and also among morphological types the diversity of geological settings and properties suggest that any single unified formation mechanism is improbable

on the origin of the bosphorus abstract the palaeozoic upper cretaceous basement palaeomorphology of the bosphorus the strait of istanbul bears the evidence of a valley of a palaeostream running to the black sea in the north a palaeobasin deeper than 160 m opening to the sea of marmara in the south and a barrier between these two features this suggest that the northern part of the bosphorus was formed mainly by fluvial activity whereas the southern part developed as a basin by faulting the recent sediment thickness exceeds 130 m in the basin indicating that the southern part of the bosphorus was once essentially depositional rather than an erosional the present form of the bosphorus was established in holocene time by the connection of the basin in the south with the stream in the north the barrier and the stream valley in the north have been deepened by erosion and faulting to form a strait connecting the black sea and the mediterranean

displacement length scaling for terrestrial and martian faults implications for valles marineris and shallow planetary grabens the displacement length ratio for the central composite graben in valles marineris inferred from topography and likely stratigraphic offsets to be d max l 4 6 x 10 3 is consistent with the scaling relations derived from terrestrial faults and grabens that also demonstrate a systematic variation in displacement with position along the structure the large 10 km depth in central valles marineris is therefore not unusual but rather should be expected for a fault system 2240 km long in contrast existing measurements of throw along the numerous shallow radial grabens in tharsis while apparently inconsistent with the scaling relations demonstrate the importance of recognizing mechanical segment length along linked or echelon graben sets faults on other planetary surfaces should scale with their terrestrial counterparts as long as they extend substantially deeper than the gravity dependent near surface rock mass zone 1 km for earth 2 5 km for mars

a healing reloading feedback control on the growth rate of seismogenic faults spatial and temporal variations in the growth rates of faults are explained in terms of a stress feedback mechanism operating in the seismogenic upper crust it is based on the idea that seismic rupture of a fault perturbs the surrounding stress field advancing the occurrence of future earthquakes on some faults that are optimally oriented while relaxing stress levels on others if post slip healing is geologically rapid then the earthquakes that are thus induced will contribute to reloading along the earlier rupture zone because of the symmetry of the optimal geometry a positive feedback is set up so that even in areas that are undergoing uniform tectonic straining some faults develop higher displacement rates and grow more rapidly while others experience reduced rates or become inactive using a thin plate elastic model for lithospheric scale faulting it is shown that this healing reloading feedback mechanism drives rapid localisation and the formation of major through going faults moving at plate boundary velocities enhanced displacement rates compared to an isolated fault develop shortly after the onset of deformation along those faults which are optimally positioned in the overall fault population thus the formation of a new plate boundary fault zone is predetermined and is a consequence of rather than the precursor of preferentially high displacement rates also fault segments located at points of rupture symmetry e g the central portion of a fault zone are reloaded more frequently and develop higher displacement rates and consequently have longer segment lengths and or larger displacement to length ratios episodic fault movement through time is a general feature of the model these predictions are consistent with available field observations over a wide range of scales thus elastic brittle failure and healing appear to be important rheological components of the lithosphere on long time scales 104 106 y as well as on the time scale of earthquake recurrence

recent ice rich deposits formed at high latitudes on mars by sublimation of unstable equatorial ice during low obliquity observations from the gamma ray spectrometer instrument suite on the mars odyssey spacecraft have been interpreted as indicating the presence of vast reservoirs of near surface ice in high latitudes of both martian hemispheres1 2 3 4 5 ice concentrations are estimated to range from 70 per cent at 60 latitude to 100 per cent near the poles possibly overlain by a few centimetres of ice free material in most places4 this result is supported by morphological evidence of metres thick layered deposits that are rich in water ice6 7 8 9 and periglacial like features10 11 found only at high latitudes diffusive exchange of water between the pore space of the regolith and the atmosphere has been proposed to explain this distribution12 but such a degree of concentration is difficult to accommodate with such processes9 13 14 alternatively there are suggestions that ice rich deposits form by transport of ice from polar reservoirs and direct redeposition in high latitudes during periods of higher obliquity9 13 but these results have been difficult to reproduce with other models here we propose instead that during periods of low obliquity less than 25 high latitude ice deposits form in both hemispheres by direct deposition of ice as a result of sublimation from an equatorial ice reservoir that formed earlier during a prolonged high obliquity excursion using the ice accumulation rates estimated from global climate model simulations we show that over the past ten million years large variations of mars obliquity have allowed the formation of such metres thick sedimentary layered deposits in high latitude and polar regions

the effect of loading rate on static friction and the rate of fault healing during the earthquake cycle the seismic cycle requires that faults strengthen heal between earthquakes and the rate of this healing process plays a key role in determining earthquake stress drop1 2 3 4 rupture characteristics5 6 and seismic scaling relations2 3 4 7 frictional healing as evidenced by increasing static friction during quasi stationary contact between two surfaces1 8 9 10 11 12 is considered the mechanism most likely to be responsible for fault strengthening2 3 13 14 previous studies however have shown a large discrepancy between laboratory and seismic field estimates of the healing rate2 3 4 14 15 in the laboratory rock friction changes by only a few per cent per order of magnitude change in slip rate whereas seismic stress drop increases by a factor of 2 to 5 per order of magnitude increase in earthquake recurrence interval but in such comparisons it is assumed that healing and static friction are independent of loading rate here i summarize laboratory measurements showing that static friction and healing vary with loading rate and time as expected from friction theory16 17 18 applying these results to seismic faulting and accounting for differences in laboratory seismic and tectonic slip rates i demonstrate that post seismic healing is expected to be retardedfor a period of several hundred days following an earthquake in agreement with recent findings from repeating earthquakes13 14 19 20

catastrophic flooding of the black sea abstract decades of seabed mapping reflection profiling and seabed sampling reveal that throughout the past two million years the black sea was predominantly a freshwater lake interrupted only briefly by saltwater invasions coincident with global sea level highstand when the exterior ocean lay below the relatively shallow sill of the bosporus outlet the black sea operated in two modes as in the neighboring caspian sea a cold climate mode corresponded with an expanded lake and a warm climate mode with a shrunken lake thus during much of the cold glacial quaternary the expanded black sea s lake spilled into to the marmara sea and from there to the mediterranean however in the warm climate mode after receiving a vast volume of ice sheet meltwater the shoreline of the shrinking lake contracted to the outer shelf and on a few occasions even beyond the shelf edge if the confluence of a falling interior lake and a rising global ocean persisted to the moment when the rising ocean penetrated across

the effects of the north anatolian fault zone on the latest connection between black sea and sea of marmara abstract the development of the strait of istanbul is also one of the principal results of the tectonics which led to the evolution of the north anatolian fault zone nafz in the marmara region 3 7 ma ago high resolution seismic profiles from the marmara entrance of the strait of istanbul show a folding which occurred after the deposition of the parallel reflected tyrrhenian sediments over the tyrrhenian strata a fondoform zone of a deltaic sequence and marine sediments of the latest sea level rising are present these sediments also display syn depositional folding this situation implies that a local compressional stress field was created over the area probably since the wurm glacial age this recent variation of the tectonic regime in the northern shelf of the sea of marmara may indicate a significant change in the development of the nafz through the sea of marmara this variation of evolution of the nafz affected the latest development of the strait of istanbul via clockwise rotation of the istanbul and kocaeli peninsulas by right lateral shearing between two zone bounding faults this rotation has led to the development of nne ssw left lateral faults in the strait of istanbul and local compressional and tensional areas explaining the compressional structures seen in the southern entrance of the strait of istanbul therefore the latest mediterranean black sea connection was established by means of the sufficient deepening of the bosphorus channel by a variation in the evolution of nafz through the sea of marmara

late glacial to holocene benthic foraminifera in the marmara sea implications for black sea mediterranean sea connections following the last deglaciation benthic foraminifera were studied from four gravity cores that penetrated holocene marine sediments in the marmara sea morphogroup and assemblage analyses reveal that the holocene sea level rise did not result in a catastrophic flooding event as proposed by w b f ryan and others whereby well oxygenated saline mediterranean waters rapidly inundated a low lying low salinity black sea lake at v7 15 ka popularly known as the noah s flood hypothesis rather the benthic foraminiferal data confirm the hypothesis that the dardanelles sill was breached by the mediterranean at v12 ka allowing saline waters to penetrate the marmara sea these saline waters reached the level of the bosphorus sill at v9 5 ka but were unable to penetrate into the black sea until after v9 1 ka because of the persistent strong outflow of brackish to fresh water from the black sea the initial colonisation of the marmara sea by benthic foraminifera is essentially synchronous with the re establishment of marine connections through the dardanelles strait at v12 ka by v10 ka ammonia dominated faunas developed on the strait exit delta v1 at the southern end of the bosphorus and at v9 1 ka the appearance of fully marine species documents the establishment of a more stratified water column over v1 finally the increase in abundance of planktonic foraminifera at the southern exit of the bosphorus after v6 1 ka reflects a decreased volume of outflow water from the black sea quantitative analysis of benthic foraminiferal morphogroups reveals that the oxygen content of subhalocline water was low below v1 5 ml l throughout the holocene and the occurrence of sapropel sediment in the deeper part of the basin suggests bottom waters may have been anoxic at times after v4 5 ka an increase in benthic foraminiferal oxic morphotypes suggests a reduction in black sea outflow and weakening of the halocline the strong and persistent stratification of the water column in the marmara sea throughout the holocene is entirely incompatible with the noah s flood hypothesis 2002 elsevier science b v all rights reserved

fluid assisted healing processes in gouge bearing faults insights from experiments on a rock analogue system on the basis of both experimental and field studies solution transfer processes are expected to be important in contributing to fault strength recovery healing under the hydrothermal conditions prevailing in large parts of the seismogenic zone however most experimental work on healing effects in faults has been done using quartzo feldspathic sliding surfaces or fault gouges under conditions in which solution transfer processes are very slow mechanisms of fluid assisted fault healing are accordingly rather poorly understood we have performed slide hold slide fault healing experiments on simulated faults containing brine saturated granular halite as a fault rock analogue halite was used because solution transfer processes are known to be rapid in this system under easily accessible conditions we studied the effects of hold time duration shear stress during hold pre hold sliding velocity and pore fluid composition on strength evolution the results show rapid fluid assisted compaction and stress relaxation during hold periods and a significant hold time dependent strengthening upon re shear the data reveal that healing resulted from both a packing density increase and a contact area strength increase during hold periods the general type of behaviour observed is similar to that observed in quartzo feldspathic gouges at room temperature although important differences were observed as well notably the time dependence of healing deviates from the log linear trend observed in gouges where solution transfer processes are absent this means that if pressure solution is an important healing mechanism in natural faults applying a log linear trend will underestimate natural fault healing rates

large rock slope failures in the highlands of scotland characterisation causes and spatial distribution abstract a comprehensive database of larger rock slope failures rsfs has been compiled and characterised for a whole mountain range possibly for the first time apart from iceland most rsfs in the scottish highlands occurred soon after deglaciation a threshold size of 0 25 km 2 focuses on rsfs which contribute significantly to gross erosion in the glacial paraglacial cycle and on the spatial concentration of this poorly recognised process database verification indicates that at least 90 of the total extant population in the highlands is covered standard mass movement typologies are broadly applicable but require some refinement to characterise rsfs in a passive margin glaciated mountain range comprised mainly of ancient metasediments most larger rsfs here are complex and difficult to categorise a continuum from cataclasmic failures including rock avalanches through arrested translational slides to almost in situ slope deformations is identified the prevailing modes of large rsf are arrested short travel translational sliding and gravitational sagging cataclasmic failure is rare and sub cataclasmic outcomes are more evident a significant class of deformations exhibits compressional rather than extensional features and may be responding to localised glacio isostatic rebound stresses the large rsf population is widely but very unevenly distributed across the main mountain areas 65 are in seven main clusters with the rest non randomly scattered previous glaciological lithological and seismotectonic explanations are insufficient to explain this spatial pattern and overlook the basic engineering geology prerequisites for failure massifs of similar relief and lithology can display intense or sparse rsf incidence geomorphological appraisal suggests an association with recently active glacial breaches of main and secondary watersheds with rsf being scarce or absent in valleys inherited from tertiary uplift and in mountain groups away from the main watersheds valleys which adapted early to ice discharge are seen as stress hardened with their slopes unlikely to reach critical thresholds for failure after subsequent reoccupations by ice concentrated erosion in the last glaciations is most likely to be found close to where breaches are actively forming or enlarging such erosion in the slope foot and valley floor may have daylighted failure planes or generated rebound stresses augmenting those from other endemic sources sufficiently to provoke widespread paraglacial rsf slope stress models for deglaciated valleys and comparative studies in other glaciated mountain ranges are required to test this concept and may assist in geohazard assessments

stratigraphy and structure of interior layered deposits in west candor chasma mars from high resolution stereo camera hrsc stereo imagery and derived elevations 1 interior layered deposits ilds within western candor chasma were studied by mapping lithologies measuring layer attitudes and comparing the stratigraphy of two adjacent mounds layering tends to dip in the same direction as the local topographic slope although at different angles regionally consistent attitudes do exist suggesting postdepositional block rotations the stratigraphy of two adjacent mounds correlates but the thicknesses of the units differ most layered material appears to have been deposited conformably with one late major unconformity several fault populations are identified and correlate well with regional faults associated with the formation of valles marineris the data suggest that here the ilds predate the faulting and may be early basin fill according to our model for ild formation ilds are deposited syntectonically during early basin collapse subsequent subsidence of surrounding areas accompanied by little or no sedimentation left the early deposits as individual mounds remnants of the former subbasins stratigraphic differences between mounds resulted from different subsidence rates of subbasins a significant change in depositional environment from depositional to a near cessation of deposition and the onset of a major erosion event possibly coincided with the opening of the main valles marineris troughs we further suggest that groundwater played an important role in the formation of sulfates the youngest unit identified not including surficial deposits is likely the result of a posttectonic regionally limited volcanic event if basin collapse continued following the cessation of deposition this model can also account for mounds within closed basins such as hebes