concentrated pulsed axial glacier flow structural glaciological evidence from kviarjokull in se iceland a detailed structural glaciological study carried out on kviarjokull in se iceland reveals that recent flow within this maritime glacier is concentrated within a narrow corridor located along its central axis this active corridor is responsible for feeding ice from the accumulation zone on the south eastern side of oraefajokull to the lower reaches of the glacier and resulted in a c 200 m advance during the winter of 2013 2014 and the formation of a push moraine the corridor comprises a series of lobes linked by a laterally continuous zone of highly fractured ice characterised by prominent flow parallel crevasses separated by shear zones the lobes form highly crevassed topographic highs on the glacier surface and occur immediately down ice of marked constrictions caused by prominent bedrock outcrops located on the northern side of the glacier close to the frontal margin of kviarjokull the southern side of the glacier is relatively smooth and pock marked by a number of large moulins the boundary between this slow moving ice and the active corridor is marked by a number of ice flow parallel strike slip faults and a prominent dextral shear zone which resulted in the clockwise rotation and dissection of an ice cored esker exposed on the glacier surface it is suggested that this concentrated style of glacier flow identified within kviarjokull has affinities with the individual flow units which operate within pulsing or surging glaciers

the development of brittle structures in an alpine valley glacier pasterzenkees austria 1887 1997 brittle structures exposed in the ablation area of pasterzenkees austria were interpreted using aerial photographs and maps covering a period of 100 years the most common structural features observed in aerial photographs are 1 normal faults which are particularly well developed along the lateral margins of the glacier and at the terminus 2 large scale tension gashes and riedel shears that develop along the northeastern lateral margin of the glacier and between ice flow units 3 thrust faults which develop at the terminus and cross cut the full width of the glacier and 4 band ogives longitudinal and transverse topographic profiles are available for the period covered in this study and ice flow velocity data are available from 1927 these data provide a means for interpreting the variations of observed structures in terms of ice flow velocity thrust faults predominantly develop during periods of glacier retreat when the glacier snout becomes an obstacle normal faults typically develop in areas of high glacier surface relief and are interpreted as gravity collapse structures the orientation of sub vertical wide open crevasses along the lateral margin of pasterzenkees varied these variations are interpreted as reflecting changes of the flow regime and indicate a transition from simple shearing to transtension during a period of ice flow deceleration

stress induced foliation in the terminus of variegated glacier alaska u s a formed during the 1982 83 surge two sets of bubble density foliation one vertical and transverse to flow and one vertical and parallel to flow developed in the ice of the terminus lobe of variegated glacier alaska during the passage of the final stages of the 1982 83 surge in june and july 1983 the transverse foliation is ubiquitous in the lower part of the terminus lobe affected by the surge but disappears abruptly over a 5 m wide zone at the boundary of the surge as delineated by measurable strain rates during the surge

tectonic processes in a surge type glacier the 1982 1983 surge of variegated glacier involved the development growth and downglacier propagation of a velocity peak associated with rapid basal sliding facilitated by high subglacial water pressures passage of the velocity peak through the glacier was preceded by an episode of longitudinal shortening and followed by an episode of elongation the deformation history of the glacier ice was dependent upon location relative to the surge nucleus and the final position reached by the propagating velocity peak ice above the surge nucleus experienced continuous and cumulative elongation ice below the final position of the velocity peak experienced continuous and cumulative shortening ice between these two points experienced shortening followed by elongation and low cumulative strain the large scale pattern of ice structure development reflects these deformation histories surging is equivalent to thrust sheet emplacement by a combination of gravity gliding over a weakened basal layer and push from behind with the gravity driven motion of the surging part of the glacier providing the push which allows the surge front to propagate the relationships established between the deformation history of surging glaciers and the development of ice structures may facilitate the interpretation of structures in thrust sheets

evaluation of trace element concentration acid leachable in sediments from river panuco and its adjacent lagoon areas ne mexico a set of forty one surface sediment samples were collected in river panuco and its adjoining lagoon areas in ne mexico to identify the enrichment pattern of trace elements the samples were analyzed for sediment texture carbonates organic carbon and acid leachable trace elements altes using autoclave method fe mn cr cu ni co pb zn cd v be ba sr as geochemical results of fe cr ni co v and sr in zone 1 indicate that erosion in the upland region sierra madre oriental mountains is very high the above feature is supported by the supremacy of finer sediments 82 12 carbonates 44 67 and organic carbon 10 74 which are brought down from the drainage basin the overall average concentration of altes mn 607 g g 1 cu 28 29 g g 1 ni 16 56 g g 1 pb 46 11 g g 1 cd 1 81 g g 1 and zn 92 18 g g 1 indicates higher values than the lowest effect level lel and effects range low erl of environmental indicators the results suggest that they are due to the increase in oil refineries metal based industries shipping activities and the effluent input which could enter the biological cycle and might create human health problems

the evolution of brittle and ductile structures at the surface of a partly debris covered rapidly thinning and slowly moving glacier in 1998 2012 pasterze glacier austria

flood delineation in a large and complex alluvial valley lower panuco basin mexico determining the extent of flooding is an important role of the hydrological research community and provides a vital service to planners and engineers for large river systems located within distant settings it is practical to utilize a remote sensing approach this study combines a remote sensing and geomorphic approach to delineate the extent of a large hurricane generated flood event in the lower panuco basin 98 227 km2 the seventh largest river system draining into the gulf of mexico the lower panuco basin is located within the coastal plain of eastern mexico and has a complex alluvial valley data sources included a landsat 5tm and landsat 7etm scene and topographic and particle size data from fieldwork and laboratory analysis the landsat 5tm image was acquired after the peak of a large flood event in 1993 whereas the landsat 7etm scene was acquired during the dry season in 2000 the increasing number of days between flood crest and the date of flood image acquisition along the river valley provided the opportunity to examine several methods of flood delineation and to consider differences in floodplain geomorphology backswamp environments were easily delineated in flooded reaches within the panuco and tamuin valleys whereas in the moctezuma valley more sophisticated methods were required because of the greater time between image acquisition and flood peak and the complex floodplain topography this included principal component pc analysis and image classification within the floodplain residual holocene terraces complicated flood mapping classification of both images allowed consideration of the influence of permanent standing water although the flooded areas were greater in the lower reaches of the study area because this portion of the valley contained large floodplain lakes the amount of inundation was actually lower remote sensing offers the ability to examine large alluvial valleys in distant settings but does not imply that geomorphic criteria should be excluded indeed because of heterogeneous floodplain topography this study illustrates the importance of including field based geomorphic analysis so that the complexity of distinct floodplain environments are considered the findings from this study are significant because most remote sensing data obtained for the purpose of flood mapping will not coincide with the flood crest thus this study provides an appropriate method for mapping flood inundation in large and complex floodplain settings after flood crest recession

experimental evidence for mantle drag in the mediterranean 1 what forces control active deformation in the central mediterranean slab pull has long been debated but no other hypothesis has been generally accepted here we analyze the role of shear basal tractions by using a thin shell modeling technique we generated a large number of models that span different sets of boundary conditions from the literature we then explored acceptable ranges of model parameters we computed residuals between model predictions and several datasets of stress directions gps measurements and tectonic stress regimes that have been produced in recent studies and then compared the best models obtained in the presence of tractions with those obtained in the absence of tractions for all tested boundary conditions and all considered datasets our results show that the only successful models are those with significant basal shear traction exerted by eastward mantle flow

application of borehole optical televiewing to investigating the 3 d structure of glaciers implications for the formation of longitudinal debris ridges midre lovenbreen svalbard digital optical televiewing optv of hot water drilled boreholes is evaluated as a technique for the investigation of englacial ice and debris structures on the basis of six boreholes drilled in the terminus region of midre lovenbreen svalbard the resulting optv logs successfully reveal several visually distinctive englacial ice properties and deformation structures e g oblique englacial fractures imaged here for the first time combining these optv logs with surface mapping has resulted in the identification of eight separate structural elements several of which can be interpolated onto 3 d grids at a node spacing of 1 m vertically and 10 m horizontally basally derived englacial sediment layers are also found to be intercalated with primary stratification elevated into near vertical planes around a central fold axis by large scale lateral folding the analysis also allows supraglacial longitudinal debris ridges to be subclassified into two types a previously described type i form which are the exposed fold axes of large scale lateral folds and a new type ii form experiencing secondary deformation by small scale horizontal folding in association with vertical displacements across arcuate shear planes in response to longitudinally compressive stresses near the glacier terminus although using boreholes to investigate glacier structure is limited e g by parallelism with vertical planes applying optv to multiple boreholes at midre lovenbreen has successfully revealed a range of 3 d structural elements at high spatial resolution as such interpolating between multiple optv logs overcomes many of the problems associated with interpretations made solely on the basis of surface based structural mapping and combining the two techniques represents a powerful glaciological tool

structure and changing dynamics of a polythermal valley glacier on a centennial timescale midre lovenbreen svalbard hambrey michael murray t glasser n f hubbard a 2005 structure and changing dynamics of a polythermal valley glacier on a centennial timescale midre lovenbreen svalbard journal of geophysical research 110 pp 1 19 rae2008

observations of surge periodicity in east greenland using molybdenum records from marine sediment cores this paper describes a unique record of glacier flow instability for east greenland during the little ice age trace metal analysis of sediment cores collected during 1998 from the noret inlet in the mesters vig area of east greenland shows two peaks in the molybdenum mo record at 495 40 years bp and 95 2 years bp this is notable as there is no molybdenum mineralization in the geology of the noret inlet catchment area molybdenum is found however in the drainage basin of mesters vig inlet just to the south of the noret inlet the molybdenum record in the noret core provides a long term surge record for the ostre gletscher a large surge type glacier in the werner bjerge that drains into mesters vig inlet the two molybdenum peaks indicate surge termination for the glacier indicating a surge recurrence interval of around 400 years

structures and fabrics in glacial ice a review abstract glaciers ice sheets and ice caps represent tectonic systems driven by gravity their movement can be studied in real time and the rheological properties and strength of ice determined from laboratory experiments and field measurements all glacial ice has primary stratification exhibited by variations in grain size bubble content and debris content as it deforms with deformation dominated by plastic flow and recrystallization accompanied locally by fracture under tension a suite of structures develops that reflects the primary fabric of the ice and the anisotropy that develops as a result of cumulative deformation initial variations in solid impurity content and strain dependent anisotropy as a result of a crystallographic fabric give rise to effective viscosity increases or decreases compared to isotropic polycrystalline ice of about a factor of ten foliation develops from inherited mostly stratification or introduced mostly ice veins or fracture traces fabric elements and from dynamic recrystallization it is largely dependent on the accumulated strain which is highest at the base and near the margins of glaciers ice sheets and ice streams folds develop largely passively due to initial amplification of irregularities in the primary stratification to variations in flow with time or to inhomogeneous flow associated with shear zones and ductile accommodation around open fractures buckle folds and boudinage mostly on a small scale occur where viscosity contrast is large mostly in basal ice thrusting and wrench faulting are documented in surging glaciers but theoretically most unlikely and rare or absent elsewhere many structures interpreted as faults are not due to shear failure but rather result from shear displacements during opening and closing of tensile fractures

multi model photogrammetric analysis of the 1990s surge of sortebrae east greenland sortebrae is a surge type tidewater glacier complex draining southeastward from the geikie plateau east greenland sortebrae s main flow unit surged around 1950 and again between 1992 and 1995 the 1990s surge affected the lower 50 km of sorte brae over an area of approximately 335 km2 over a period of 5 km surge velocities in the order of kilometres per annum are about 100 fold the quiescent velocities multi model photogrammetric analysis shows a thinning of the reservoir zone of up to 219 m and thickening of the receiving zone of up to 74 m the surge transported approximately 18 6 km 3 of ice down glacier the total calving volume as a result of the surge amounted to 11 7 km 3 equivalent to a calving flux of 3 9 7 3 km a 1 the surge characteristics and environmental setting suggest that the surge mechanism involves a switch in the subglacial drainage this surge of sortebrae is more similar to the fast short alaskan type surges than to the sluggish long svalbard type surges

evolution of variegated glacier alaska u s a prior to its surge on presente l evolution saison apres saison des changements dans la geometrie et la vitesse du glacier et on tente de rattacher ces variations a la deformation de la glace et au glissement basal

spatial trends in the geochemical composition of sediments in the panuco river discharge area gulf of mexico major and trace elements organic matter carbonates loss of ignition grain size gravel sand silt clay and qualitative mineralogical composition were determined on surficial marine sediments sampled during the stormy february dry may and rainy september seasons in the coastal area adjacent to panuco river discharges into the gulf of mexico the sediments supplied by the river move in a north east direction and are deposited in the north east extreme of the studied area terrigenous sediments show a strong association of al2o3 with fe2o3 na2o k2o p2o5 rb cu zn organic matter clay and grain size mz mineralogical analysis shows that they are formed by quartz kaolinite montmorillonite illite montmorillonite and biotite the highest metal concentration of cu 25 mg kg zn 155 mg kg pb 50 mg kg and organic matter 1 26 was observed in the sampling points located very close to the river mouth a statistical analysis was done with the information contained in the variables five significant factors explain 77 of the total variance factor 1 is due to sediments from a terrigenous source factor 2 corresponds to sediments from a biogenous source factor 3 is associated to sediments with heavy minerals factor 4 is due to co concentration and factor 5 is due to ni concentration the sediments supplied from the river had a short term local impact on the sediment distribution as observed by the carbonate and heavy mineral concentration of the sediments

characteristics of surge type glaciers glaciers can be divided into two classes according to their flow behavior normal relatively steady annually averaged flow rate and surge type pronounced cyclic flow variations having a typical periodicity of 10 100 years we have examined the population statistics of 2356 glaciers in the st elias mountains yukon territory canada and estimate that 151 6 4 of these glaciers are surge type to explore how various glacier attributes are associated with surging we compare the probability of surging associated with various subsets of the complete population to appropriate reference values in this way potential influences on surge tendency can be examined for the 55 drainage basins analyzed there is a pronounced spatial variation in the concentration of surge type glaciers but no obvious environmental control can be evinced within the study area the greatest concentration lies in the northern st elias mountains a region of high topographic elevation that is experiencing rapid tectonic uplift analysis of the influence of length on surge tendency reveals that long glaciers have a significantly greater probability of being surge type than short glaciers the surge probability increases monotonically from 0 61 for very short glaciers 0 1 km to 65 1 for long glaciers 10 75 km this result suggests that ice sheets and ice caps or at least portions of them should have a high probability of surging tributary glaciers have a greater tendency to surge than trunk glaciers presumably because they may themselves be surge type and may additionally participate in surges of the trunk glacier the nonrandom geographical distribution of surge type glaciers is not simply a consequence of the variation from basin to basin of the glacier length distribution surge type glaciers tend to have a higher overall elevation than normal glaciers the elevation of the highest point of the accumulation zone the elevation of the snow line and the elevation of the lowest point of the ablation zone on average exceed the corresponding elevations for normal glaciers there is no significant difference between the overall slopes of surge type and normal glaciers although there is a tendency for surge type glaciers to have greater slope in the accumulation zone and lesser slope in the ablation zone than normal glaciers although the prevalent flow direction for glaciers in the yukon data set is to the north surge type glaciers tend to flow to the east and southeast this orientation influence is probably explained by the fact that many of the longest glaciers also flow to the east and southeast

structural evolution of variegated glacier alaska u s a since 1948 an excellent photographic database comprising 12 sets of vertical aerial photographs taken between 1948 and 1983 has enabled the structural glaciology of surge type variegated glacier alaska u s a to be analyzed for a period that spans two surge cycles and includes the effects of three surges the glacier wide patterns of crevasse development at the end of each of these surges which occurred in 1947 48 1964 65 and 1982 83 were remarkably similar despite differences in surge intensities and extents at the end of each surge a three fold longitudinal zonation of crevasse orientation characterised that part of the glacier that had been affected by surge activity this zonation comprises i transverse crevasses in a narrow upper zone ii superimposed longitudinal and transverse crevasses in an extensive middle zone and iii longitudinal crevasses in a narrow lower zone the main difference between patterns produced by successive surges was small variations in the extent of the three zones during quiescence the most intense crevasse development occurs in the upper glacier in the latter part of quiescence and is a function of increasingly steep down glacier velocity gradients developing in the buildup to the impending surge some crevassing also develops in the central part of the glacier in mid quiescence that is not related to the surge nature of the glacier but to normal flow processes over bedrock there is no structural evidence to indicate that any of the tributaries of variegated glacier surge this observation suggests that the bulb like loops in the medial moraines at variegated glacier form during quiescence as a result of the steady flow of the tributaries into the stagnant trunk glacier rather than as a result of tributary surges

debris entrainment and transfer in polythermal valley glaciers hambrey mj bennett mr dowdeswell ja et al 1999 debris entrainment and transfer in polythermal valley glaciers journal of glaciology 45 149 69 86 published 1999

glaciofluvial crevasse and conduit fills as indicators of supraglacial dewatering during a surge skeiðararjokull iceland

propagation of a glacier surge into stagnant ice the propagation of the surge of variegated glacier into its terminal lobe was observed by daily surveying of a longitudinal line of closely spaced markers extending up glacier from a stagnant zone of thin 40 m nearly motionless ice near the terminus across a front zone to a surge zone of thicker 100 m rapidly moving 20 m d 1 ice above within the front zone there were large angles of upward motion 30 compressive longitudinal strain rates 0 1 d 1 and upward vertical velocities 5 m d 1 within the surge zone the ice motion was nearly parallel to the ice surface and longitudinal gradients were small the deformation pattern produced microcracking exfoliation and buckling of surface ice longitudinal cracking longitudinal chasms and an increase in glacier volume the front zone propagated at an average speed of about 40 m d 1 or roughly twice the surge speed of the ice above the front this factor is determined by the thickness jump across the front finite element modeling constrained by measured geometry and surface velocity was used to deduce the velocity and stress at depth the velocity in the surging zone occurs almost entirely by sliding the sliding rate drops abruptly beneath the center of the front zone to zero in the stagnant zone a comparison of basal velocity and shear stress distributions indicates a highly lubricated area beneath the upper part of the front zone and a locked area beneath the lower part of the front zone normal stress at the bed is not significantly different from overburden and there is no high compressive normal stress on the bed to act as a pressure dam to obstruct water flow through the front zone

a model of the glaciar horcones inferior surge aconcagua region argentina the deformation resulting from a surge in 1985 of glaciar horcones inferior is analyzed using structural geological models during the surge previously continuous debris cover was deformed by the formation of regularly separated and rotated ice blocks suggesting a system of linked rotational extensional faults block tilting was measured from photographs taken shortly after the surge showing rotation of the debris covered surface fault inclination was assumed to be coincident with the debris free side of the block glacier advance during the surge was obtained by comparing pre surge aerial photographs with the position of maximum advance after the surge glacier thinning was estimated from the debris surface average lowering relief generated at lateral scarps coincident with shear zones and ice thickness measurements after surge termination three independent sets of information geometry of the deformation i e depth of detachment fault traces fault spacing block rotation glacier thinning and net advance limit possible interpretations surface geometry suggests a domino style or a linked planar rotational extensional fault system in the observed configuration however these models can only explain a 12 13 extension glacier thinning suggests 30 local extension and total glacier advance implies 16 minimum extension which does not account for some frontal compression as observed a linked curved rotational extensional fault model fits the data well implying a significant degree of internal deformation within each block this model satisfactorily explains the observed deformation produced by the surge it may also explain some modes of fast glacier flow since the observed style of block tilting is present in other glaciers with high relief

an assessment of surge induced crevassing and the formation of crevasse squeeze ridges 1 evidence for extensive crevassing is preserved on the deglaciated forelands of many surging glaciers as crevasse squeeze ridges csrs at some point these crevasses make direct connection with the bed in order to become sediment filled and full depth connections have been inferred from turbid water up wellings in crevasses and the formation of concertina eskers the dynamics of seven surging glaciers are assessed using a linear elastic fracture mechanics approach to determine the likely directions of fracture and controlling parameters for mode i crevasses extensional surface strain rates are insufficient to promote top down full depth penetration for small crevasse spacing 5 m surface strain rates are sufficient for top down crevassing to depths of 4 12 m explaining the extensive surface crevassing associated with glacier surging as has been shown in other settings top down full depth crevassing is only possible when water is added and approaches 97 of the crevasse depth the provision of sufficient meltwater to facilitate this is problematic due to the extensive surface crevassing unless water can move along connected crevasses to a dominant water capturing crevasse for ice thicknesses greater than 200 m basal water pressures in excess of 80 90 of flotation are required for full depth bottom up crevassing field evidence suggests that this is the default for surging glaciers and that on occasion water pressures may even become artesian csrs found across many surging glacier forelands and ice margins most likely result from the infilling of basal crevasses driven for the most part bottom up by high basal water pressures

glacier surge mechanism 1982 1983 surge of variegated glacier alaska the hundredfold speedup in glacier motion in a surge of the kind the kind that took place in variegated glacier in 1982 1983 is caused by the buildup of high water pressure in the basal passageway system which is made possible by a fundamental and pervasive change in the geometry and water transport characteristics of this system the behavior of the glacier in surge has many remarkable features which can provide clues to a detailed theory of the surging process the surge mechanism is akin to a proposed mechanism of overthrust faulting

anomalous inland influx of the river indus gulf of kachchh india the gulf of kachchh is a funnel shaped macrotidal water body located in the arid region of northwestern india with 50 cm annual rainfall and insignificant fluvial input the gulf waters however have high suspended matter time series measurements of total suspended matter tsm and synchronous validated hydrodynamic modeling have been used to decipher the dispersal pathways and the sources of the high turbidity contrary to the prevalent offshore reducing trend for most of the indian coast the gulf is anomalous for having an enhanced turbidity at the mouth with lower concentrations in the inland areas the hydrography of the gulf is dominated by strong alongshore currents at the mouth which move in out during flood ebb and undergo cyclic dynamic changes with tidal phases the flood tidal currents amplify inland with propagating tides pulling in the offshore waters and acting as a feeder of high saline turbid offshore waters into the gulf most of which are trapped inland due to time lag of ebb and flood between the outer and the inner gulf based upon the distribution maps of tsm and clays in the water column it is deduced that a large segment of the gulf is nourished by contributions from the indus river

fracturing block faulting and moulin development associated with progressive collapse and retreat of a maritime glacier falljokull se iceland since 2007 falljokull in southeast iceland has been undergoing passive downwasting providing an ideal opportunity to study a range deformation structures developed in response to ice marginal collapse and retreat an integrated terrestrial lidar ground penetrating radar and glaciological structural study of the clean debris free ice at the margin of falljokull has allowed a detailed model of the surface and subsurface 3d structure to be developed collapse of the glacier margin takes the form of a multiple rotational failure controlled by large scale down ice dipping normal faults as the fault bound blocks of ice are displaced downslope they rotate leading to localized compression and the formation of down faulted graben like structures moulins present within the marginal zone of falljokull are closely associated with the zones of relatively more intense brittle deformation which crosscut the glacier a model is proposed where the moulins have formed in response to the progressive collapse of englacial drainage channels located along down ice dipping normal faults the preferential development of the moulins and englacial drainage channels along the normal faults weakens the ice along these structures promoting or even accelerating further collapse of the ice margin the complex pattern of surface lowering within the marginal zone of falljokull has also been shown to be directly related to movement on the main faults controlling the collapse of the ice margin this evidence suggests that structurally controlled collapse may in some instances have a profound effect on glacier surface lowering and geodetic mass balance measurements

manganese fluxes from mississippi delta sediments abstract massive sediment deposition on the mississippi river delta establishes reducing conditions sufficient to bring about mn dissolution in the top millimeters of sediment as a result significant fluxes of dissolved mn pass from the delta sediments to the overlying water column this process is examined by study of chemical partitioning of mn in river particulates and delta sediments and from interstitial water chemistry remobilized mn is actively transported away from the delta area with aluminosilicate detritus thereby providing excess mn to the deep gulf of mexico at the expense of the delta sediments

tributary glacier surges an exceptional concentration at panmah glacier karakoram himalaya four tributaries of panmah glacier have surged in less than a decade three in quick succession between 2001 and 2005 since 1985 13 surges have been recorded in the karakoram himalaya more than in any comparable period since the 1850s ten were tributary surges in these ten a full run out of surge ice is prevented but extended post surge episodes affect the tributary and main glacier the sudden concentration of events at panmah glacier is without precedent and at odds with known surge intervals for the glaciers interpretations must consider the response of thermally complex glaciers at exceptionally high altitudes and of high relief to changes in a distinctive regional climate it is suggested that high altitude warming affecting snow and glacier thermal regimes or bringing intense short term melting episodes may be more significant than mass balance change

the structural geology of a surge type glacier abstract the range of deformation structures found in surge type variegated glacier alaska is similar to that found in many thin skinned thrust belts and includes foliations folds dip slip and strike slip faults thrust faults and fractures the development of structural relationships and the overall structural assemblage can be related to the deformation histories of quiescent and surge phases of motion the surge phase dominates the formation of brittle structures because of the large stresses and strain rates associated with it the relationship between downglacier verging overturned folds with hinge lines transverse to flow and a family of transverse arcuate thrust faults is characteristic of structural development in the lower part of the glacier during the surge longitudinal foliation develops mainly from sedimentary stratification in the upper part of the glacier in a marginal transpressive deformation regime during quiescent phase flow from broad accumulation basins the structural relationships in this surge type glacier may aid in the interpretation of structures in other gravity driven tectonic settings