geomorphological evidence for jokulhlaups from kverkfjoll volcano iceland abstract jokulhlaups glacial outburst floods are known to have drained along the jokulsa a fjollum river in iceland during the holocene however little is known about their number age source and flow characteristics this paper provides detailed geomorphological evidence for jokulhlaups that have routed from the kverkfjoll ice margin and hence into the jokulsa a fjollum erosional evidence of jokulhlaups from kverkfjoll includes gorges cataracts spillways subaerial lava steps and valley wide scoured surfaces depositional evidence includes wash limits boulder bars cataract fill mounds terraces slackwater deposits and outwash fans some of these landforms have been documented previously in association with jokulhlaups however subaerial lava surfaces that have been scoured of the upper clinker gorges within pillow hyaloclastite ridges gorges between pillow hyaloclastite ridges and subaerial lava flows subaerial lava lobe steps cataract fill mounds and boulder run ups are previously undocumented in the literature these landforms may therefore be diagnostic of jokulhlaups within an active volcanic rifting landscape the nature and spatial distribution of these landforms and their stratigraphic association with other landforms suggest that there have been at least two jokulhlaups through kverkfjallarani the biskupsfell eruption occurred between these two jokulhlaups kverkfjallarani jokulhlaups were very strongly influenced by topography geology and interevent processes that together determined the quantity and nature of sediment availability such controls have resulted in jokulhlaups that were probably fluidal turbulent and supercritical over large areas of the anastomosing channel bed kverkfjallarani jokulhlaups would have had highly variable hydraulic properties both spatially and temporally the knowledge of flow characteristics that can be gained from jokulhlaup impacts has implications for recognising jokulhlaups in the rock record and for hazard analysis and mitigation within similar landscapes and upon other glaciated volcanoes

exploration for pleistocene aggregate resources using process depositional models in the fort mcmurray region ne alberta canada abstract at present the fort mcmurray region of alberta canada is experiencing an aggregate supply shortage both syncrude and suncor oil sand mines have exploited most of their local reserves and haul costs are rapidly increasing from distant new sources previous aggregate studies in this region have focused on mapping known deposits rather than explaining the distribution of gravel by using process depositional models as exploration tools and exploring for sources closer to the aggregate users aggregate deposits in the mcmurray region are associated with two major pleistocene geomorphic events 1 glacial lake mcmurray and 2 a catastrophic flood from glacial lake agassiz aggregate resources associated with late pleistocene glacial lake mcmurray are subaqueous fan deposits beaches and deltas several large aggregate deposits are found along the benchlands of the lower clearwater and athabasca valleys these valleys are a former spillway system eroded by a catastrophic flood from glacial lake agassiz 9900 years before present bp discovery of other aggregate resources in the mcmurray region will be best accomplished by understanding the flood soillway depositional patterns and regional deglacial history

boulders as a signature of storms on rock coasts this paper is the first review of coastal boulder studies it serves as a peer reviewed introduction to a special issue on the topic of boulders as a signature of storms on rock coasts since 2004 and the indian ocean tsunami most coastal boulder research has been focused on using boulders as sedimentary signatures of palaeo tsunami events and the most commonly used transport equations typically suggest that large boulder deposits are products of tsunami rather than storms there is growing empirical evidence demonstrating on inter annual to century timescales that storm waves are capable of transporting and depositing boulders of significant size at elevations well above sea level current process studies of how boulders are eroded transported and deposited have not received wide attention by rock coast geomorphologists or palaeoenvironmental reconstruction scientists this special issue is framed around the goal of highlighting our current understanding of the role of storm waves as a driving mechanism for boulder erosion transport and deposition here we review the current state of knowledge about boulder dynamics boulder responses to storms and boulders as sedimentary signatures of storm events we identify gaps in our conceptual and quantitative understanding lastly we propose means of addressing research gaps improving consistency between researchers and collecting multi purpose data this review and the papers contained within the special issue provide an improved understanding of coastal dynamics particularly the role storms can play in influencing erosion rates and depositional patterns of coarse material i e boulders or larger which has hitherto been under represented in the literature

evidence of tsunami sedimentation on the southeastern coast of australia in coastal regions the highest magnitude storms cannot always be invoked to account for large scale anomalous sediment features any coastline in the pacific ocean region can be affected by tsunamis including australia which historically lacks evidence of such events geologically tsunamis along the new south wales coast have deposited a suite of holocene features that consist of anomalous boulder masses either chaotically tossed onto rock platforms and backshores or jammed into crevices highly bimodal mixtures of sand and boulders and dump deposits consisting of well sorted coarse debris in addition many coastal aboriginal middens were distributed by such events within estuaries tsunamis have left a record of stranded run up ridges that have been interpreted mistakenly as cheniers dating of such deposits indicates that several events have affected this coastline since 3000 bp in contrast to storm waves tsunamis can leave a depositional imprint of their passage characterized by chaotic sort

stable imbrication and delicate unstable settings in coastal boulder deposits indicators for tsunami dislocation abstract medium sized and coarse debris pebbles and boulders can exhibit patterns of setting particularly if they are elongated or tabular these patterns such as imbrication indicate certain transport processes mostly as to direction and character many years of observation and measuring of coarse coastal deposits are the basis for the conclusions presented here on environmental transport processes their character and their energy beside imbrication special emphasis is given to unstable or delicate settings of large boulders that evidently have remained in these positions from hundreds to thousands of years this deserves an explanation to how they arrived at these positions and why they have not changed into a more stable position given an environment of constant energy input along coastlines the discussion lays emphasis on whether both settings of mega boulders can be indicative of tsunami transport processes

storm wave currents boulder movement and shore platform development a case study from east lothian scotland article i nfo understanding the distribution of wave energy on shore platforms is important for models of the long term development of both shore platforms and backing cliffs little is known however of the magnitude of the wave currents generated on shore platforms in storms this study uses the distribution of boulders of different sizes on a shore platform on the north sea coast of scotland to investigate patterns of storm wave current velocities in storms over the last 40 240 yr blocks as large as 9 m 3

quaternary geology and geomorphology of the dinosaur provincial park area and surrounding plains alberta canada the identification of former glacial lobes drainage diversions and meltwater flood tracks abstract the quaternary geology and geomorphology of the lower red deer river drainage basin centred on the dinosaur provincial park badlands provides information on pre late wisconsinan drainage patterns and the dynamics of former lobes of the laurentide ice sheet in western canada patterns of deglaciation proglacial lake evolution and spillway incision are also reconstructed based upon the distribution of surface materials and glacial glaciofluvial landforms the empress group fluvial and glaciolacustrine sediments which could be as young as 27 ka bp infill the precursor red deer river and its tributaries and document the initial advance of glacier ice into southern alberta glaciotectonic disturbance of older sediments and bedrock the production of deformation tills and the construction of a megafluting complex and cupola hills record the advances of a glacier lobe centred over the study area stratified inter and intra till beds record pulses of subglacial meltwater between phases of subsole deformation the thickening of tills towards the margin of the lobe represents a till wedge an expected product of sediment advection by glaciers moving over deformable beds the eastern margin of the glacier lobe is demarcated by the interlobate suffield hummocky moraine belt which contains overprinted thrust ridges which record diachronous oscillations of neighbouring lobes within the ice sheet proglacial and glaciofluvial sediments were deposited in the area in association with proglacial lake bassano patricia which drained eastwards when the suffield moraine was dissected by spillways changes in the size of glacial lake bassano patricia are clearly documented by a sequence of spillway incisions which culminated in the erosion of scabland topography and the initiation of a new course for the red deer river a 15 km southward diversion of the main channel in distinct contrast to the documented incision histories of other small rivers in alberta one tree creek and little sandhill creek did not start major incisions of the quaternary sediments over buried valley positions until the late holocene when environmental conditions were characterized by higher precipitation

origin and large scale erosional features of glacial lake spillways in the northern great plains deglaciation of the northern great plains produced two basic types of fluvial systems 1 depositional regimes produced by the action of glacial melt water that formed outwash plains and 2 highly erosive systems produced by the sudden rapid drainage of glacial lakes that formed spillways spillways are huge deeply incised trenches that display all of the characteristics of fluvial channels glacial lakes drained in weeks or months and discharges of 10 5 m 3 s were attained at bankfull stage seven spillway systems studied were formed as a consequence of the sudden rapid draining of glacial lakes many other large valleys in the mid continent area and other glaciated regions were probably formed by the same process spillways consist of deeply incised inner channels commonly flanked by broad scoured outer zones initial stages of flow produced shallow anastomosing channels continued erosion produced longitudinal grooves streamlined erosional residuals and surficial boulder lag deposits inner channels developed by the enlargement of one or more centrally located longitudinal grooves the development of erosional residuals was initiated by the incision of shallow anastomosing channels the interchannel areas were progressively modified from irregular quadrilateral or elliptical shapes to an equilibrium minimum drag lemniscate shape as glacial lake drainage proceeded correlations between length and width length and area width and area and length width ratio and k a shape parameter of the lemniscate loop are very high for all erosional residuals studied although only 20 of the residuals display an equilibrium lemniscate shape stable relationships between length width and area of erosional residuals are therefore established very early and are maintained throughout the erosional modification to the lemniscate shape the only shape factor tested which can be used to quantitatively differentiate lemniscate from nonlemniscate erosional residuals is the position of maximum width as measured by the ratio of the length from the lee to the point of maximum width to the total length xm l the mean xm l ratio for erosional residuals in a spillway segment is an indication of the relative duration of flood flows that produced the spillway

outburst flood origin of the central kalamazoo river valley michigan usa abstract geomorphic evidence and stratigraphic information from boreholes suggest that the oversized central kalamazoo river valley ckrv in southwest michigan resulted from a catastrophic outburst flood emanating from subglacial channels under the saginaw lobe of the laurentide ice sheet the ckrv occurs as a deeply incised trench over 2 km wide and in excess of 50 m deep situated in a reentrant formed by the lake michigan saginaw and huron erie lobes the course of the ckrv follows an irregular flow path that bisects the kalamazoo moraine of the lake michigan lobe erosional terraces near the mouth of the channel indicate that lake michigan lobe meltwater drained eastward prior to the westward saginaw outburst prior to valley formation the lake michigan lobe had retreated westward to at least the lake border moraine with the lake michigan lobe absent to impede flow drainage from the ckrv proceeded southwesterly until draining into glacial lake chicago near st joseph michigan the outburst originated from a system of saginaw tunnel channels that display convex up flow profiles and contain eskers meltwater drainage transitioned from subglacial to ice marginal and proglacial environments during the interval represented by the outburst the saginaw lobe appears to have been in a relatively stationary position

groundwater lake interactions i accuracy of seepage meter estimates of lake seepage abstract the use of seepage meters to identify nearshore seepage patterns and to quantify seepage in lakes was evaluated with a monte carlo simulation model the model simulated seepage flux as would be derived from seepage meter measurements along a transect extending from the shore of a hypothetical lake to 40 or 100m offshore along the transect simulated seepage velocities decreased exponentially with distance from shore according to patterns measured at narrow lake alta and lake sallie mn to determine statistical parameters needed in the model seepage flux was measured in situ with closely spaced seepage meters at four different sites in narrow lake seepage velocities within a small area of lakebed were log normally distributed and the variance was positively correlated with mean seepage flux the modeling indicated that the most sensitive parameter affecting the accuracy of seepage meter estimates of seepage patterns and average seepage flux along the transect was the variability in the spatial distribution of seepage flux within a small area of lakebed there was little improvement in the accuracy of estimates of seepage patterns or transect flux when more than ten seepage meters were simulated along the transect when the transect was sampled more than twice or when seepage meters along the transect were simulated to follow a stratified rather than a systematic design

sedimentology of rocky shorelines 2 shoreline megaclasts on the north shore of oahu hawaii origins and history abstract limestone megaclasts up to 96 t in weight rest on a coastal rock platform near sunset beach on the north shore of oahu hawaii they occur in seaward dipping imbricate clusters and as solitary clasts the rock platform is subject to large swell waves and very large waves associated with winter storms and tsunami a series of photographs covering the period from ca 1905 to 1996 show episodic rearrangement of megaclasts on the platform and the appearance of new megaclasts near the platform edge the largest solitary megaclast ca 96 t was emplaced on the platform between 1940 and 1950 possibly by the 1946 aleutian tsunami and has moved twice since then in ca 30 m jumps along two different trajectories larger clasts have been broken from the platform edge and emplaced on the platform only by very large wave events whereas formation and movement of smaller tabular clasts ca 30 40 t appear to be a continuously ongoing process on the surface of the rock platform partial detachment of clasts by marine erosion processes along joints and cracks in the limestone bedrock facilitates their complete detachment from both the platform edge and platform surface the larger numbers of megaclasts emplaced on the north and northwest sectors of the platform relative to other sectors are attributed to exertion of maximum wave power on these sectors due to a combination of steep slope and ramp like submarine topography

catastrophic flooding from glacial lake wisconsin abstract glacial lake wisconsin was a large proglacial lake that formed along the southern margin of the laurentide ice sheet during the wisconsin glaciation it was formed when ice of the green bay lobe came into contact with the baraboo hills in southwestern wisconsin and blocked the south flowing wisconsin river during early glacial recession the ice dam failed catastrophically and the lake drained in about a week despite early recognition of the former lake and the likelihood that it failed catastrophically outflow rates during the failure have not been previously evaluated estimates based on step backwater modeling indicate that peak discharge was between 3 6 and 5 3 10 4 m 3 s in the lower wisconsin river as an alternate method we used a previously derived empirical relationship between lake volume and peak discharge for dam break events from a digital elevation model altered to incorporate isostatic depression we estimated the lake volume to be 87 km 3 just prior to dam breach suggesting that the flooding magnitude was as high as 1 5 10 5 m 3 s at the outlet adjusting these results for downstream flood wave attenuation gives a discharge of around 4 4 10 4 m 3 s in the lower reach which closely matches the results of the step backwater modeling these estimates of discharge from the catastrophic failure of ice marginal lakes improve our understanding of the processes that have produced the morphology and behavior of present day upper midwest river systems

glaciofluvial erosional morphology and sediments of the coronation spondin scabland east central alberta spatially discontinuous meltwater channel networks on the canadian prairies are usually interpreted as having formed subaerially in front of the retreating laurentide ice sheet evidence in the coronation spondin scabland east central alberta supports an alternative formation by progressive channelization of a subglacial sheetflow of water the scabland is an integrated channel network with varying degrees of anabranching the channels having highly variable sizes shapes and orientations enhanced scour at some channel confluences reflects contemporaneous channel utilization channels also display convex up concave up and undulatory along channel profiles with some junctions at the same elevations longitudinal grooves in large scale channels are associated with numerous boulder deposits residual hills demarcated by channels display composite and streamlined forms superimposed on residuals are erosional transverse bedforms longitudinal grooves and undulating surfaces that indicate submergence

distribution geomorphology and lithofacies of cliff top storm deposits examples from the high energy coasts of scotland and ireland abstract cliff top storm deposits ctsds occur on cliffs at elevations of up to 50 m above sea level at exposed sites on the deep water coasts of the british isles this study examines the distribution geomorphology and lithofacies of ctsds at sites from shetland orkney caithness and the outer hebrides in scotland and from the aran islands in galway bay in ireland ctsds are generated largely by the quarrying of blocks from the cliff top and transported by green water bores across cliff top platforms and ramps to be deposited in backing ridges or as debris spreads maximum boulder sizes reach 48 m 3 but it is likely that much larger blocks can be quarried prior to disintegration during transport eye witness accounts and field mapping demonstrate that formation and modification of ctsds has continued during major storms over recent decades recent ctsds bury a range of man made debris but older deposits lack this and instead show weathering effects that indicate a longer residence time in shetland osl dates on intercalated sands suggest that the oldest ctsds date from 800 ad radiocarbon dates on shell buried inside ctsd ridges relate to major storms between 1700 and 1900 ctsds represent an overlooked archive of storm sedimentation that has great potential for the elucidation of local storm chronologies ctsds also provide evidence of wave impacts on any part of the cliff face or top in fundamental contrast to the concentration of wave action at the cliff foot implicit in traditional models of the erosion of rock coasts

imbricate and fitted fabrics in coastal boulder deposits on the australian east coast boulder deposits that exhibit a tightly interlocked or fitted fabric are common along the coast of new south wales and other coasts the fitted fabric in which adjacent clasts are packed in a three dimensional interlocking mass gives considerable stability to boulder deposits and enables them to resist movement even in extreme storms on exposed high energy coastlines a radiocarbon age of 4780 ka on the cement of a calcite cemented shell and rock breccia within the fabric of a fitted boulder deposit on the new south wales central coast indicates that the boulders were deposited soon after the end of the postglacial marine transgression and that they have remained stable since that time other boulder deposits along the same coast show that boulder fitting can develop in less than a century thereby imparting considerable stability and persistence to coarse marine elastic deposits

a multi proxy study of changing environmental conditions in a younger dryas sequence in southwestern manitoba canada and evidence for an extraterrestrial event multi proxy analyses of a sequence spanning the younger dryas yd in the glacial lake hind basin of manitoba provides insight into regional paleohydrology and paleovegetation of meltwater rivers and lakes spanning 4000 yr the sequence is controlled by 25 new accelerator mass spectrometry ages this lake dammed by the laurentide ice sheet overflowed into lake agassiz the pre yd interval records rapid sedimentation from meltwaters that headed in proglacial lakes in the canadian prairies that are known to have been catastrophically released when ice or sediment barriers were breached pollen in this phase is dominated by pre quaternary forms eroded from paleocene bedrock at the onset of the yd at 12 8 cal ka the sudden appearance of concentrations of nanodiamonds high temperature magnetic spherules platinum and iridium provide evidence of an extraterrestrial et event that others have identified at more than 40 sites in north america major changes in oceans and climate and the catastrophic outflow of nearby lake agassiz at the onset of the yd may be related lower water levels and a reduction of souris river inflow to lake hind followed which are reflected by more clayey and organic rich sediments and a decrease in pre quaternary palynomorphs this may have resulted from the deepening of river valleys caused by the release of meltwater triggered by the et event wetlands then began to develop leading to peat deposition from 12 3 to 11 cal ka this was followed by a fluvial episode depositing sand and then by increased holocene aridity that resulted in accumulation of a thick sequence of dune sands a dry woodland environment with a mix of conifers especially picea and larix and deciduous trees especially populus and quercus covered the uplands from 13 to 10 cal ka

evaluating the impacts of huge waves on rocky shorelines an essay review of the book tsunami the underrated hazard abstract tsunami the underrated hazard draws together and summarizes a wealth of information about the nature impacts and causes of tsunamis written from a natural hazards perspective the book stresses that large tsunamis can affect even protected coasts that have not experienced large tsunamis historically many deposits and erosional features described and discussed as tsunami signatures have yet to be linked specifically with tsunamis cited references in the book do not necessarily support a tsunami origin for these features because accepted scientific citation practices have not been followed although rocky shorelines in southeastern australia the hawaiian islands and elsewhere generate and preserve a variety of boulder and block deposits and erosional features their sediment dynamics and geomorphology are poorly studied and unequivocal criteria for distinguishing between deposits of storms and tsunamis have yet to be developed despite its shortcomings this book should be on the library shelves of all marine geoscientists who study modern and ancient shorelines however it should be used with great circumspection because the process product relationships it assumes are equivocal

sedimentology of rocky shorelines 4 coarse gravel lithofacies molluscan biofacies and the stratigraphic and eustatic records in the type area of the pleistocene hulopoe gravel lanai hawaii abstract during the pleistocene the south flank of lanai was the site of repeated erosion and deposition as a consequence of glacio eustasy superimposed on tectono isostasy throughout this time terrigenous and bioclastic gravel was generated along mainly rocky shorelines gravelly sediment was deposited in topographically low areas of the shoreface and inner shelf that later were uplifted isostatically the sedimentary lithofacies and biofacies in these deposits are distinctive but they represent a deposystem and suite of environments that hitherto have not been studied systematically these unrecognised circumstances have fuelled controversies about the nature and significance of the hulopoe gravel most notably the claim that it represents a mega tsunami deposit the hulopoe gravel in its type area displays a lithofacies succession that encompasses a complete disconformity bounded transgressive regressive cycle on a sand poor rocky shoreline this succession incorporates not only a distinctive vertical assemblage of rocky shoreline litho and biofacies but also internal disconformities that record episodes of erosion and non deposition during shoreline migration repetition of the lithofacies succession imparts overall stratigraphic order to the hulopoe gravel four unconformity bounded transgressive regressive cycles correspond to eustatic highstands of oxygen isotope stages 5 and 7 superimposed on continuing tectono isostatic uplift driven by growth of the island of hawaii this study of the hulopoe gravel demonstrates that the sedimentary record of mixed volcaniclastic carbonate depositional systems developed on rocky shorelines of tropical and subtropical oceanic island coasts can be preserved this record may include depositional products of both transgressive and regressive shorelines although tsunami and giant submarine landslides are known to occur in the hawaiian islands deposits and features that result from tsunami inundation above the shoreline such as might be expected from landslide related mega tsunami have not been recognised in the type area of the hulopoe gravel rocky palaeoshoreline records on oceanic volcanic islands may yield oceanographic and climatic clues that complement data obtained from other palaeoshoreline types

an extreme wave event in eastern yucatan mexico evidence of a palaeotsunami event during the mayan times the yucatan peninsula mexico has typically been considered a tectonically stable region without significant seismic activity in contrast the region is one that is regularly affected by hurricanes a detailed survey of ca 100 km of the eastern yucatan and cozumel coast identified the presence of ridges containing boulders measuring 1 m with up to three ridges at some locations the ridges reach five metres in height and their origin is associated with extreme wave event ewe activity previously modelled tsunami waves from known seismically active zones in the region muertos thrust belt and south caribbean deformed belt are not of sufficient at the yucatan peninsula to have produced the boulder ridges recorded in this study the occurrence of hurricanes in this region is more common but two of the most destructive hurricane gilbert 1988 and hurricane wilma 2005 produced coastal waves too small to have created the ridges recorded here in this paper a new tsunami model has been generated that indicates a tsunami event may have caused the ewe that resulted in the deposition of the boulders ridges