a critical reappraisal of preconsolidation pressure interpretations using the oedometer test over the past 70 years a number of methods have been proposed for the interpretation of the characteristic vertical effective yield stress or preconsolidation pressure of compressible soils as defined using the standard oedometer test the concept of the preconsolidation pressure has been extraordinarily useful in geotechnical engineering for analysing and predicting settlement behaviour and for normalizing other engineering parameters for comparative purposes defining this characteristic stress however is often problematic and relies heavily on graphical techniques that are subject to some uncertainty particularly when using semi log plots for this purpose this paper illustrates fundamental difficulties with the interpretation of oedometer test and presents an alternative technique for defining unambiguous values of the vertical effective yield stress

early holocene deglaciation of expedition and strand fiords canadian high arctic terrestrial and marine records provide the first reconstruction of past glacial events on west central axel heiberg island lateral moraines along expedition fiord define an early holocene ice margin when a trunk glacier occupied the inner half of the fiord limited sediment accumulation in the outer fiord 8 4 ka bp principally by calving of an unstable ice front to a position well upvalley of the present ice limit rapid deglaciation is evidenced by i an absence of ice marginal landforms and related marine biofacies ii a scarcity of raised marine sediments and iii exceptionally thin sediments 5 20 m in the inner fiord a transition from a hiatella arctica mya truncata macrofossil assemblage to an astarte borealis mya truncata assemblage reflects a change from moderate to low energy depositional environments at the fiord head by 7 9 ka bp the extensive ice advance into expedition fi

the intrinsic behaviour of a decomposed granite soil the intrinsic mechanics of a decomposed granite soil were investigated by triaxial tests at standard pressures and at high pressures up to 35 mpa to compare its behaviour in its saturated partially saturated and dry states in each case it was found that the behaviour could be described within a critical state framework with particle breakage as the principal means of plastic volumetric compression the behaviour of partially saturated samples compacted at around the optimum water content was found not to differ appreciably from that of saturated samples in contrast tests on dry samples revealed a state boundary surface for the dry soil which exists outside that of the saturated soil sieve analyses showed this to result from the fact that the soil in its dry state was subject to a smaller amount of particle breakage although the critical state friction angle is not affected by the presence of water the location of the state boundary surface at higher volumes stresses for the dry soils results in the

seafloor geomorphology and glacimarine sedimentation associated with fast flowing ice sheet outlet glaciers in disko bay west greenland fast flowing outlet glaciers currently drain the greenland ice sheet gis delivering ice meltwater and debris to the fjords around greenland although such glaciers strongly affect the ice sheet s mass balance their glacimarine processes and associated products are still poorly understood this study provides a detailed analysis of lithological and geophysical data from disko bay and the vaigat strait in central west greenland disko bay is strongly influenced by jakobshavn isbrae greenland s fastest flowing glacier which currently drains 7 of the ice sheet streamlined glacial landforms record the former flow of an expanded jakobshavn isbrae and adjacent gis outlets through disko bay and the vaigat strait towards the continental shelf thirteen vibrocores contain a complex set of lithofacies including diamict stratified mud interbedded mud and sand and bioturbated mud deposited by 1 suspension settling from meltwater plumes and the water column 2 sediment gravity flows and 3 iceberg rafting and ploughing the importance of meltwater related processes to glacimarine sedimentation in west greenland fjords and bays is emphasised by the abundance of mud preserved in the cores radiocarbon dates constrain the position of the ice margin during deglaciation and suggest that jakobshavn isbrae had retreated into central disko bay before 10 6 cal ka bp and to beyond isfjeldsbanken by 7 6 7 1 cal ka bp sediment accumulation rates were up to 1 7 cm a 1 for ice proximal glacimarine mud and 0 007 0 05 cm a 1 for overlying distal sediments in addition to elucidating the deglacial retreat history of jakobshavn isbrae our findings show that the glacimarine sedimentary processes in west greenland are similar to those in east greenland and that variability in such processes is more a function of time and glacier proximity than of geographic location and associated climatic regime

sedimentary processes of canadian arctic fjords abstract conceptual models of circulation and sedimentation in arctic fjords are presented to illustrate the current understanding of these environments circulation is a vigorous process in these fjords and is enhanced by the loss of the freshwater cap during the long winter period of near zero inflow the process of brine rejection during the formation of sea ice and the role of glaciers and icebergs injecting freshwater at depth on the other hand the presence of sea ice blocks reduces the mixing action of wind which may otherwise represent the largest input of energy to fjord circulation it also provides a freshwater layer on melting and may in some circumstances damp the amplitude of tides during summer large loads of glacial sediment entering arctic fjords are separated into streams of overflowing suspended load and bed load in the presence of salt water as the concentrations of suspended load in the freshwater are normally much less than required to overcome the density of the salt water deposition occurs throughout the fjord by rapid settling of flocculated particles from the overflowing brackish water and from grain flows in the proximal environment created as the fluvial traction carpet moves over the delta foreset slope after sediment has been deposited it may be remobilized by slides which in turn may develop into fully turbulent flows as they move down the fjord floor a range of deposits from slump debris to minor turbidites are postulated to occur with the flocculated muds although not all have yet been examined in the arctic fjord stratigraphic record sea ice is an important sedimentological agent in arctic fjords it passively carries fluvial aeolian and colluvial material which is subsequently released from the ice during the stage of puddle draining at break up sea ice also actively incorporates fine and coarse sediments up to large boulders during freezing along the shores in winter and by wave and tidal current washing controlled by the presence of the ice during break up

the influence of lateral spreading on settlements beneath a fill the discrepancy between calculated consolidation settlements and measured settlements under a 3 8 m high section of an earth embankment is investigated in this paper a conventional one dimensional analysis underestimated the observed settlement by 40 a two dimensional finite element analysis was carried out to assess the effects of lateral spreading on vertical movements and the results were in close agreement with the measured values key words case history consolidation finite element analysis settlement

the glacimarine sedimentary environment of expedition fiord canadian high arctic abstract expedition fiord is a small shallow inlet on the west coast of axel heiberg island near 80 n latitude it receives runoff and sediment at its head from a 1079 km 2 drainage basin 72 of which is glacier covered subbottom acoustic survey and cores from the fiord floor were used to assess the sedimentary environment most of the sediment is deposited within 3 km of the inflow from suspension in the overflowing cap and by gravity flows on the foreset beds of the delta occasionally weak turbidity currents reach the mid fiord where they deposit fine grained sediments icebergs from a large calving glacier in an adjacent fiord raft additional sediment especially to the outer part of the fiord they also scour the seafloor although the persistent ice cover and slow currents in the fiord restrict this process except near the inflow the total sediment accumulation since deglaciation is less than 20 m and the rates of 0 5 1 mm yr have not varied significantly to the present a thicker deposit in the outer fiord is probably related to an early holocene glacier margin near that location

glaciomarine sedimentation in disraeli fiord high arctic canada abstract disraeli fiord represents a glaciomarine environment unique to the north coast of ellesmere island featuring floating glacier tongues multi year landfast sea ice and a strongly stratified water body which results from enclosure of the fiord by ward hunt ice shelf it is a very low energy depositional environment even at sites proximal to glaciers sediment enters the fiord by interflow and is deposited through suspension settling ice rafting is precluded by the year round sea ice cover sedimentation rates in the inner fiord since about 7000 yrs b p are estimated to be 5 10 cm ka a reflection of the limited sediment influx from the cold based glaciers which contact the fiord changes in sediment structure through the holocene reflect changes in the rate and process of sediment input as well as changes in fiord circulation all of which relate to regional climate during deglaciation early holocene sedimentation rates were orders of magnitude greater than at present subglacial meltwater was the dominant source of inflow with sediment transported in turbid plumes as over or interflow and deposited through suspension settling this is supportive of other studies indicating that a pronounced climatic amelioration led to warm based glaciers at this time

holocene glacimarine sedimentary environments in fiords of disko bugt west greenland abstract acoustic and sedimentary properties of three fiord systems were examined in the region of disko bugt west greenland to understand variability in the processes rates and sources of sediment delivery during the late glacial and holocene kangerluk and kangersooq of western disko are dominated by meltwater inputs of sediment from local ice fields of the island interior modern sediments are delivered primarily via overflow currents rainout occasional bottom currents and small amounts of iceberg rafting where exposure to baffin bay allows penetration of the west greenland current 14 c and acoustic derived accumulation rates for the last 1 2 ka vary from about 1 mm a 1 in distal fiord settings to more than 5 mm a 1 in proximal sites adjacent to actively building deltas these rates are generally larger than has been observed in other greenland and baffin bay fiords the tidewater terminus of inland ice at ikerasak is also meltwater dominated but produces lower than expected sediment accumulation due to low gradients of the outlet ice and resistant substrates these high latitude west greenland fiords are subarctic in character and contrast significantly with colder polar type fiords at similar latitudes in east greenland sediment deposition which was focused in the outer disko fiords during the late glacial and early holocene is due to one of two possible mechanisms standstill of local ice or enhanced rafting of sediment from disko bugt icebergs this study contributes to the debate on the extent of glaciation and holocene spatial variability in fiord processes of west greenland

marine sedimentation at a calving glacier margin a 2 month study at a subpolar tidewater glacier was conducted at anvers island antarctic peninsula lat 64 s to improve understanding of sedimentary processes and associated deposits in glacial marine settings data collected in the ice proximal environment were 1 brash ice size distribution and melt rates to assess sediment source and transport mechanisms 2 conductivity temperature turbidity depth cttd profiles water samples and sediment trap catches to study processes and patterns of sediment dispersal 3 bottom cores and grabs to document recent glacial marine sedimentation and 4 remotely operated vehicle video surveys of the ice terminus and sea bottom to obtain images of physical and biological processes the water column is stratified and a halocline occurs at 20 30 m water temperature ranged from 1 to 1 6 c salinity was 32 34 and suspended solids were 3 5 mg l well above the bottom ephemeral turbid horizons contain 8 15 mg l suspended solids rare surface plumes and a quasipermanent turbid layer produced by resuspension during calving events reach 25 35 mg l meltwater drains from the glacier surface but no subglacial meltwater was detected directly entering the sea the most important sources of sediment appear to be the direct melting of the submerged ice front and melting of calved glacial ice most fragments of floating ice melt within 1 km of the ice front some sediment may be contributed as low density 1 1 g cm 3 algae bound sediment pellets by meltwater streams draining the ablating ice surface sediment enters the stratified water column and is moved by tidal and wind driven circulation marine sedimentation rates are low 3 mm yr relative to depth of bioturbation resulting in unstratified sandy mud with dispersed clasts

early deglaciation of the british irish ice sheet on the atlantic shelf northwest of ireland driven by glacioisostatic depression and high relative sea level understanding the triggers and pace of marine based ice sheet decay is critical for constraining the future mass loss and dynamic behaviour of marine based sectors of the large polar ice sheets in greenland and antarctica numerical models which seek to predict this behaviour need to be calibrated against data from both contemporary and palaeo ice sheets and the latter requires accurate reconstruction of former ice sheet extent dynamics and timing marine geophysics sediment cores benthic foraminiferal assemblages and radiocarbon dating are used to reconstruct the extent of the last british irish ice sheet biis and the timing and style of its retreat on the atlantic shelf northwest of ireland shelf edge moraines and subglacial till recovered in cores from the outer continental shelf are dated to younger than 26 3 ka cal bp and indicate an extensive ice sheet at the last glacial maximum lgm that was grounded to the shelf edge nested arcuate moraines record the subsequent episodic retreat of the ice sheet across the shelf lithofacies and associated foraminiferal assemblages demonstrate that this retreat occurred in a glacimarine environment as a grounded tidewater margin and that high relative sea level and cold waters prevailed during retreat radiocarbon dates indicate that the timing of initial ice sheet retreat from the shelf edge occurred in the interval between 26 3 and 24 8 ka cal bp during the period of minimum global eustatic sea level and that the ice sheet had retreated to the mid shelf by 24 8 ka cal bp the donegal bay moraine a large moraine at the mouth of donegal bay records a major stillstand and readvance of the ice sheet during deglaciation between 20 2 and 17 9 ka cal bp estimated retreat rates of 5 5 35 m a 1 across the shelf demonstrate that retreat was slow it is noteworthy that retreat was initiated in the absence of ocean warming and when eustatic sea level was at a minimum the sea level rise that initiated deglaciation from the shelf edge therefore is inferred to have been a product of local glacio isostatic crustal depression rather than external forcing this demonstrates that marine based sectors of ice sheets can trigger their own demise internally through glacio isostatic adjustment and it provides an explanation for the early retreat of the biis on the atlantic shelf during the global lgm glgm

predictive model for uniaxial compressive strength for grade iii granitic rocks from macao abstract determination of the uniaxial compressive strength ucs of rocks is an important task for rock and geotechnical engineering applications direct measurement is expensive time consuming and even infeasible in some circumstances due to the difficulty in obtaining core samples therefore empirical models are particularly favorable to engineers especially in the preliminary design stage however there is a lack of predictive ucs model for granite of weathering grade iii but it is well recognized to be crucial to the design of pile foundations on granitic bedrocks in this study a reliable predictive model will be developed under the bayesian framework an extensive experimental program was performed in this study to construct a comprehensive database of the measurements of uniaxial compressive strength point load index schmidt rebound hammer value p wave velocity effective porosity specific gravity and dry density it has been proven that the proposed model possesses satisfactory predictive performance

weathered rock characterization using drilling parameters the characterization of weathered rocks by the use of drilling parameters is presented drilling parameters obtained from the drilling process monitoring system during the installation of soil nails into weathered rocks are used in this investigation a new drilling index pi simplified from the concept of the specific energy is used in an attempt to differentiate weathered rocks with pi or the penetration rate boundaries of weathered rocks between 1 soil and rock ranges and 2 grade ii and grade iii rocks in accordance with the six fold rock material decomposition grade are identified for weathered rocks in the soil range quantitative characterization has been established in this study by using the drilling parameters an empirical equation has been established for estimating the standard penetration resistance n value from the drilling parameter pi which is used in turn to determine the mohr coulomb friction angle based on the work of schmertmann although this approach tends to yield a slight

models of glaciomarine sedimentation and their application to the interpretation of ancient glacial sequences abstract this paper argues that glaciomarine environments can be regarded as special glacially influenced types of continental margin environments e g continental shelf slope rise and basin plain knowledge of the stratigraphic architecture and typical sedimentary sequences of non glacial margins is becoming well known but remains limited for those that have been glacially modified the principal influences on sedimentation in these environments relate to the glacial sediment input controlled by relief of basin margin glacier thermal regime and ice flow dynamics and depositional environments influence of traction currents substrate relief and proximity to nearby ice margins typical ranges of sedimentation rates can be established for glacially influenced continental margin environments and these may provide a framework for ancient sequences starvation of sediment supply to glacially influenced continental margins is common the nature of sub ice shelf sedimentation a model that has been applied to many ancient glacial sequences is critically reviewed the significance of such sedimentation in the rock record has probably been exaggerated because of oversimplistic interpretations of diamictite sequences existing process models of glaciomarine sedimentation derived from study of modern environments are sometimes difficult to employ in investigation of ancient sedimentary sequences because simple lithofacies criteria and typical vertical profiles are not available to aid in interpretation in addition compositional data emphasized by many workers for distinguishing glaciomarine from continental glacial diamict ite s frequently fingerprint sediment source and not mode of deposition the importance of facies analysis methods for isolating depositional environments is illustrated by three examples of ancient glaciomarine sequences these are the early proterozoic gowganda formation 2 3 ga of northern ontario canada the late proterozoic port askaig formation 670 ma of scotland and ireland and the late cenozoic yakataga formation 20 ma to recent of the gulf of alaska these examples illustrate the significance of detailed genetic studies of ancient glacial rocks in the interpretation of palaeogeographic and tectonic settings diamictite units in ancient glaciomarine sequences cannot be easily interpreted in terms of climatic or ice advance retreat cycles because of the varied controls on diamict accumulation and diamictite preservation in marine basins

environmental assessment from the sedimentary record of high latitude fiords the sedimentary record of fiords at high latitude where global change may be occurring earliest and will be greatest has the potential for assessment of environmental change at both low resolution the scale of millennia and high resolution decadal to less than daily unlike the lacustrine record which has been used very successfully in these studies the sedimentary processes and thus the sedimentary deposits of fiords differ 1 in the role of salt water in inhibiting mixing and promoting flocculation and through the role of sea ice 2 in the exchange of mass and energy with the much larger ocean beyond and 3 in the role of benthic biota in the sedimentary environment the work reviewed in this paper shows that fiord sediments are being used to assess sedimentary and oceanic processes as well as glacial periglacial and geomorphic history and that they are important proxies for long term climate and hydrology recommendations for advancing this work include long term monitoring of conditions in fiords and their drainage basins so that the transfer relations can be more solidly constructed from the proxy of fiord sediment integration of results from fiords in opposite polar latitudes and among proxies especially from lacustrine and ice core records will produce valuable insights assessment of the range of conditions in fiords from the most polar to temperate regions is important to building models of their processes and understanding of the paleoenvironmental signals that can be interpreted from each type

sedimentation in a deep glacier fed lake lake tekapo new zealand surface sediments cores and seismic reflection profiling delineate sedimentary environments and processes of sedimentation in lake tekapo sedimentation is dominated by the godley river which forms an extensive delta in the northern third of the lake delta growth accounts for 55 of annual sediment deposition in winter sandy muds are deposited at the top of the delta slope where they may move under gravity as a surficial slide oversteepening of the upper slope also generates deep seated failures the entire 20 km2 of delta slope is subjected to rotational slumping which episodically reworks large volumes of sediment down the delta slope sedimentation rates decrease surface sediments get finer and varves become better developed in the lake basin sediments are parallel bedded varves which contain typical winter summer annual cycles as well as minor non annual flood varves annual varve thickness and semi annual varve frequency are determined by variations in the discharge of the godley river sedimentation in the basin accounts for 40 of the budget and sedimentation rates decrease with distance from the delta except at the distal end of the basin where turbid underflows are stopped by the rising lake floor beyond the basin sedimentation rates decrease abruptly coriolis deflection of inflowing river water increases sedimentation rates down the eastern shore the remaining 5 of the sediment is deposited on the lateral slopes and shoulders where sediments form a thin muddy veneer over basement which occasionally slumps to the basin floor

reverse flow in turbidity currents the role of internal solitons pickering hiscott 1985 have demonstrated amply the presence of reverse flow units within the thick bedded calcareous wacke tcw beds of the turbiditic cloridorme formation middle ordovician gaspe peninsula quebec canada these reverse flow units are underlain and overlain by units which reveal flow in the primary obverse direction in this paper a model is proposed for this reverse flow based on the probable nature of the primary turbidity flow it appears that the initial flow was highly elongated thickness h length l with h 500 m velocity u 2 m s 1 and sediment concentration c 1 25 o the rate of momentum loss of the flow is estimated by means of a useful parameter which we call the drag distance symbol dd defined by where h and l are the thickness and length of the flow respectively ccd is a combined drag coefficient representing friction on the bottom and at the upper interface and fcd is a form drag coefficient related to the shape and size of the head dd is the distance travelled by a current of constant h and l flowing over a horizontal bottom and obeying a quadratic friction law for an e fold reduction in velocity simple considerations confirmed by our own experiments described in this paper show that such an elongated turbidity current cannot be reflected as a whole from an adverse slope when the nose of the current reaches the slope it forms a hump which surges backwards and sooner or later breaks up into a series of internal solitons the latter probably numbering 4 7 will cause reverse flow at a given point as they pass by provided that the residual velocity in the tail is not too great flow in the original obverse direction will be re established after the passage of the solitons quiescent periods in front of between and behind the solitons when soliton associated currents cancelled out the residual obverse flow would allow the deposition of thin mud drapes additional flow reversals observed in a few of the tcw beds cannot be explained readily by the re passage of solitons since wave breaking at the ends of the basin would cause massive energy loss internal seiches are the preferred explanation for these later reversals

submarine landforms and glacimarine sedimentary processes in lomfjorden east spitsbergen understanding the role of fjords in modulating the long term interaction between ice sheets and glaciers with the surrounding ocean requires the investigation of glacigenic landform and sediment archives in svalbard there is a wealth of data from fjords in west spitsbergen that constrains the glacial history of this sector of the svalbard barents sea ice sheet sbis since the last glacial maximum lgm and the nature and timing of subsequent ice retreat in contrast however very little is known about the glacial history of fjords in east spitsbergen this paper combines multibeam swath bathymetry sub bottom profiles lithological data and radiocarbon dates from lomfjorden svalbard to provide the first insights into the dynamics of tidewater glaciers and associated glacimarine sedimentary processes in a northeast spitsbergen fjord at the lgm a fast flowing ice stream drained the sbis through lomfjorden serving as a tributary to a south north flowing ice stream in hinlopenstretet ice advance is recorded by streamlined bedrock glacial lineations and drumlins a radiocarbon date of 9 7 ka bp from the outer fjord provides a minimum date for retreat of this ice stream and suggests that lomfjorden was ice free earlier than fjords in west spitsbergen ice retreat occurred in a slow and step wise manner indicated by the presence of recessional moraines and de geer moraines by 4 5 ka bp the local tidewater glaciers had probably retreated inland of their present positions the limited extent of glacigenic landform assemblages in front of these glaciers implies that any holocene re advances were probably restricted the principal sedimentary processes during deglaciation were suspension settling from meltwater causing deposition of weakly stratified bioturbated mud in ice distal settings at rates of 0 02 0 08 cm a 1 and gravitational mass flows forming sandy turbidites in ice proximal areas iceberg ploughmarks and ice rafted debris provide evidence for the presence of large icebergs during deglaciation our data suggest an early and extensive deglaciation in east spitsbergen fjords and show that previous reconstructions of the extent of the sbis need to be revised as new data emerges from east spitsbergen the data confirm that tidewater glaciers from different regions of spitsbergen behaved differently since the lgm and that variations in landform sediment assemblages occur even within geographically adjacent fjords

an empirical approach for estimating shear strength of decomposed granites in galicia spain decomposed granites are often found in galicia spain where they are referred to as jabres similar decomposed granites are also found in many other parts of the world granite weathering rarely produces an homogeneous altered rock mass with all material decomposed to the same degree or even a simple weathering profile where the degree of alteration decreases progressively with depth this paper presents an empirically based approach that allows estimation of the shear strength of this type of materials in terms of mohr coulomb cohesion and internal friction angle values the approach is based on back analysis of failed slopes in decomposed granites and it is implemented through simple in situ testing and classification of the weathered granite treating it as a soil material an advantage of the used approach is that it allows prediction of shear strength values at different locations within the deposit in a quick and economical way from which average values of shear strength parameters can be computed this is particularly important when considering the heterogeneous nature of decomposed granite formations in relation to the scale of the engineering work involved analysis of three slopes instability cases in jabres in galicia illustrating the approach are described in detail these correspond to a road cut a natural slope and the wall of an open pit mine

work as a criterion for determining in situ and yield stresses in clays discussion this is a discussion of a paper by the same title which appeared in vol 24 canadian geotechnical journal pp 549 564 the authors of the original paper are d e becker j h a crooks k been and m g jefferies

land sea correlations and evolution of the cambridge fiord marine basin during the last deglaciation of northern baffin island abstract cambridge fiord functions as a major outlet trough whenever laurentide ice approaches the eastern coast of baffin island during the last glacial maximum late foxe glaciation an outlet glacier occupied most of the fiord possibly terminating as far seaward as buchan gulf glacier retreat began prior to 8800 yr b p and was punctuated by the formation of two onshore moraines with upper age limits of 7900 and 7200 yr b p correlative offshore moraines recognized on seismic reflection profiles formed prominent submarine sills which partitioned the fiord into three basins these formed effective sediment traps that restricted the seaward migration of debris flows and turbidites thus facilitating the accumulation of thick 100 m stratified glacialmarine sediments in the inner fiord correlations of onshore and offshore moraines allow time lines to be placed within an offshore seismic stratigraphic section that is inaccessible to piston coring resultant estimates of sediment accumulation rates give a mean value of 2 34 10 6 m 3 yer for deposits trapped in the inner fiord basins these thick sequences of sediments do not represent extended foxe wisconsin time periods but rather were rapidly deposited in the inner fiord during the last deglaciation

sediments of ice dammed self draining ape lake british columbia the glacier damming ape lake has withdrawn from its neoglacial terminal moraines in the lake since early in this century at an average rate of 15 m a as a result the first known drainings of ape lake occurred in october 1984 and august 1986 in each event about 54 of the volume of the lake was lost through a tunnel in the damming glacier most of the remaining water was held in the deep basin of the lake behind partially breached neoglacial terminal moraines as the glaciers have withdrawn the character of the sediments has changed sediments in the deep basin of the lake are varved but the grain size especially of the summer deposits has decreased and rates of sedimentation have decreased from about 4 mm a to less than 2 mm a in shallow water deposition of varved sediments has given way to the deposition of massive sediments at rates of less than 1 mm a ice rafted debris is rare in deep water despite the presence of calving bergs during and following the first draining significant subaerial

estimation of the shear strength of gravel deposits based on field investigated geological factors abstract a gravel deposit is a composite material composed of gravel and soil matrix the largest size of gravel in the study areas generally ranges from 100 mm to 300 mm the estimation of the shear strength of gravel deposits often requires large scale in situ direct shear tests or large scale triaxial tests in laboratory both kinds of the large scale tests are expensive and the triaxial tests using remolded specimens with reduced size gravel may lower estimate the shear strength of gravel deposits this study first estimates the shear strength of gravel deposits employing their topographic characteristics which are the envelopes of slope inclinations and slope heights each envelope corresponds to a strength parameter of a gravel deposit then field investigation is conducted to obtain geological factors such as the diameter in the grain size distribution curve corresponding to 50 finer d 50 gravel content and the unconfined compressive strength of matrix the strength parameter and the field investigated geological factors are correlated through linear regression the geological factor that most influences the shear strength of the studied gravel deposits is the unconfined compressive strength of matrix the regression model is tested using field investigated data obtained from other locations and the derived cohesion and friction angles are compared to the results in literature the study establishes an economic way to estimate the shear strength of gravel deposits in central taiwan however the idea is applicable to gravel deposits bimrock alluvium or colluvium elsewhere in the world in which large gravels or cobbles exist and shear strength cannot be estimated by conventional methods

laminated sediments in glacimarine environments diagnostic criteria for their interpretation abstract fine grained laminated deposits are often reported from contemporary and ancient glacimarine sedimentary sequences laminated glacimarine sediments form by a variety of processes including suspension settling from turbid overflow plumes turbidity current deposition and contour current activity subglacial deformation of pre existing sediments may also produce laminated deposits in the form of glacitectonite and deformation till the development of diagnostic criteria for genetic discrimination of laminated glacimarine sediments is important both for their correct interpretation in sedimentary sequences and also for the accurate reconstruction of former glacier extent and geometry as laminated sediments may form in subglacial ice proximal and ice distal environments this paper reviews the processes by which laminated glacimarine sediments form and their resulting sedimentology the aim is to provide a synthesis of diagnostic sedimentological criteria for laminated glacimarine deposits that will assist in the interpretation of such sediments in the geological record laminated sediments are genetically differentiated on the basis of sedimentary structures bedding contacts stratigraphic relationships and macrofaunal content bioturbation these attributes also facilitate discrimination between glacimarine and glacilacustrine rhythmites the paper concludes by discussing the glaciological significance of laminated glacimarine sediments in terms of glacier hydrology reconstructions of former ice dynamics and basal thermal regime