methodology of the last climatic cycle reconstruction in france from pollen data abstract a numerical method has been devised to reconstruct the climate of the last climatic cycle from pollen data reliable annual reconstructions have been published recently for the two french long sequences of la grande pile and les echets covering the last 140 millennia this paper gives more details on the method used it proposes new reconstructions based on an extended modern pollen data base these reconstructions are consistent with the previous ones especially detailed information is obtained on the seasonal characteristics of climate computations of gcm on the climate variations from 125 kyr to 115 kyr b p are confirmed for western europe the insolation variations have induced at that time a decrease of seasonality accompanied by an increased cyclonic activity in winter this has been the beginning of the first ice growth after the last interglacial other glacier growth phases are detected at the end of substage 5c and particularly at the end of substage 5a

radio echo sounding studies of englacial water movement in variegated glacier alaska une crue glaciaire du variegated a ete enregistree a l aide d un emetteur mono impulsion de 3mhz les discontinuites intraglaciaires ont ete observees dans le domaine des 12 a 30 mhz les changements dans la forme des echos sont interpretes en terme de redistribution de l eau dans les canaux glaciaires et les cavites reliees au lit a quelque distance a l aval

shelf wide erosion deposition and suspended sediment tranport during cyclone winifred central great barrier reef australia abstract observation of shelf sediments collected immediately before and after cyclone winifred crossed the central great barrier reef shelf 1 february 1986 confirmed that the storm produced a normally graded mixed terrigenous carbonate storm layer extending 30 km offshore in water up to 43 m deep distinct post winifred changes in the cross shelf distribution of organic carbon and carbonate in the mud fraction of the sediment suggest that suspended sediment transport was extensive and that the storm layer had multiple sediment sources on a shelf wide scale the storm layer is composed almost entirely of reworked shelf sediment erosion depths were greater on the mid shelf 20 40 m water depth than on the inner shelf 6 9 cm and 5 1 cm respectively particles finer than medium sand were eroded and transported out of the mid shelf the inner shelf portion of the storm layer formed by the combination of three sediment sources including 1 seaward transport of terrigenous sediment in buoyant freshwater flood plumes 2 resuspension and settling of inner shelf sediment and 3 resuspension and shoreward transport of mid shelf sediment mass balance calculations predict that at least 10 30 of the inner shelf storm layer is composed of mid shelf mud combined wave and wind forced currents probably resuspended mid shelf material and drove the suspended fraction alongshelf and shoreward a minimum distance of 15 km the results suggest that tropical cyclones are capable of sporadic but efficient cross shelf transport of suspended sediment on shallow cyclone prone shelves suspended sediment may easily be exchanged between adjacent sedimentary facies in ancient shelf sequences the transport history of the mud will be complex and stratigraphically equivalent facies may have similar mud types but completely different sands

intense hurricane transports sand onshore example from the pliocene malbusca section on santa maria island azores portugal abstract southern cliffs on santa maria island in the azores archipelago north atlantic ocean feature submarine volcanic sequences inter bedded with pliocene coralline algal limestone shelly coquinas and mixed volcaniclastic calcarenite sandstone within the 20 m sedimentary succession at malbusca a singular 5 m sandstone bed is distinguished by dark and light laminae dominated alternately by heavy minerals and carbonate detritus carbonate grain size varies between that of coarse silt and very fine sand the basal part shows coarser and more poorly sorted sand in an upward transition to increasingly finer carbonates accessible over a lateral space of 34 m the big bed is shouldered against and overlaps the remnants of a drowned rocky shore with a paleorelief of 4 m that preserves intertidal to shallow subtidal biotas extrapolated from the big bed s rock face 1830 m 2 and the width of the eroded shelf on which it resides 8 m calculations yield a projected volume of 14 500 m 3 unique to the island the big bed is interpreted as a major hurricane deposit that moved sand from an offshore bar in an onshore path such an event fits the context of the pliocene warm period during which global el nino conditions were more intense than today

the insular shelves of the faial pico ridge azores archipelago a morphological record of its evolution shelves surrounding reefless volcanic ocean islands are formed by surf erosion of their slopes during changing sea levels posterosional lava flows if abundant can cross the coastal cliffs and fill partially or completely the accommodation space left by erosion in this study multibeam bathymetry high resolution seismic reflection profiles and sediment samples are used to characterize the morphology of the insular shelves adjacent to pico island the data show offshore fresh lava flow morphologies as well as an irregular basement beneath shelf sedimentary bodies and reduced shelf width adjacent to older volcanic edifices in pico these observations suggest that these shelves have been significantly filled by volcanic progradation and can thus be classified as rejuvenated despite the general volcanic infilling of the shelves around pico most of their edges are below the depth of the last glacial maximum revealing that at least parts of the island have subsided after the shelves formed by surf erosion prograding lava deltas reached the shelf edge in some areas triggering small slope failures locally decreasing the shelf width and depth of their edges these areas can represent a significant risk for the local population hence their identification can be useful for hazard assessment and contribute to wiser land use planning shelf and subaerial geomorphology magnetic anomalies and crustal structure data of the two islands were also interpreted to reconstruct the long term combined onshore and offshore evolution of the faial pico ridge the subaerial emergence of this ridge is apparently older than previously thought i e before 850 ka

the climate in europe during the eemian a multi method approach using pollen data the last interglacial period the eemian offers a testbed for comparing climate evolution throughout an interglacial with the current warm period we present here results from climatic reconstructions from 17 sites distributed across the european continent allowing an assessment of trends and regional averages of climate changes during this period we use a multi method approach to allow for an improved assessment of the uncertainties involved in the reconstruction in addition the method takes into account the errors associated with the age model the resulting uncertainties are large but allow a more robust assessment of the reconstructed climatic variations than in previous studies the results show a traditional three part eemian with an early optimum followed by slight cooling and eventually a sharp drop in both temperatures and precipitation this sequence is however restricted to the north as this latter change is not observed in the south where temperatures remain stable for longer these variations led to marked variation in the latitudinal temperature gradient during the eemian the difference between the two regions is also noticeable in the magnitude of changes with greater variations in the north than the south some evidence is found for changes in lapse rates however a greater number of sites is needed to confirm this

remote sensing of sand distribution patterns across an insular shelf oahu hawaii sandy substrate is important as a resource habitat and dynamic region of the bathymetry we find that sand storage across the insular shelf of oahu hawaii is controlled most strongly by general insular shelf morphology and to a lesser degree by hydrodynamic energy shelf sand is predominantly found in water depths less than or crossing the 10 m contour we use remote sensing to identify and classify 14 037 individual sand deposits in nine study regions a supervised classification algorithm aggregates these into five classes with 14 subclasses almost 63 of all sandy surface area falls into two subclasses of the channels and connected fields class 1 major channels and 2 unchannelized drainage these subclasses connect regions of sediment production to regions of sediment storage on the insular shelf surface this study is the first to quantitatively analyze and classify shelf sand deposits in a high volcanic island coral reef setting

a synthetic aperture radio echo experiment at storglaciaren sweden une experience de sondage par echo radio sensible a la polarisation a ete effectuee sur le glacier storglaciaren suede dans le but de rechercher et d examiner les echos radio emanant de cibles individuelles sous glaciaires six cibles principales ont ete identifiees et la force des echos indique que ces cibles sont probablement des cavites renfermant de l eau il n a pas ete possible de dire si ces cavites font parties d un systeme connecte de canaux sous glaciaires

submarine depositional terraces in the tyrrhenian sea as a proxy for paleo sea level reconstruction problems and perspective abstract in the last decade great effort was put in the study of relative sea level changes on mediterranean coastlines through the integration of geophysical modelling and proxy data of paleo shorelines in this paper we show potential and limitations of using additional marine geomorphic sedimentary markers for earlier and lower sea levels these markers are submarine depositional terraces sdts i e deposits formed by a set of small prograding sedimentary wedges having a terraced shape and found at variable shallow water depths mainly the first 150 m on continental and insular shelves in the tyrrhenian sea the shallowest terraces near shore have their edges at depths between 10 m and 30 m approximating the modern local storm wave base level their formation is thought to be associated with the modern sea level highstand and thus can be used as the modern analogue for deeper terraces formed in the past when the sea level was on the middle and outer shelf mid shelf terraces have their edges at variable depths between 40 m and 90 m and probably formed during the last sea level rise they show a patchy spatial distribution and a large variability in their internal structure so that they are not suitable for correlation on a regional scale shelf edge terraces have their edges at depths between 120 m and 170 m which is close or deeper than the last glacial maximum lgm sea level stand they show a remarkable lateral continuity and a prograding internal structure similar to those at shallower depth and thus represent a proxy for the sea level position at around 20 ka however the position of sdts edges is not a direct measure of paleo sea level positions because their depth depends on a complex interplay of several factors such as the base of the storm wave and its variation in response to coastal physiography as well as the occurrence of subsequent erosional or depositional processes depending on the geophysical and mapping methods used to determine their depth the associated error range can also differ based on the analysis of these complexities and a wide range of physiographic settings of the tyrrhenian sea we discuss these error ranges in order to assess potential and limitation of the sdt for analyses of vertical mobility of an area

marine terrace development on reefless volcanic islands new insights from high resolution marine geophysical data offshore santa maria island azores archipelago abstract submerged marine terraces are relict coastal erosional landforms now underwater due to rising sea level and or land subsidence using as case study the shelf around santa maria island north atlantic ocean we intend to advance our knowledge on the formation and preservation of these features on reefless volcanic islands santa maria is an ideal place to study their combined generation since it displays a sequence of subaerial and submerged marine terraces the latter not studied before distributed between 7 230 m in elevation and 40 140 m in depth respectively based on some geological constraints we investigated a possible correlation between the formation of the different terraces with known sea level changes our results suggest that the spatial distribution of marine terraces at santa maria depends on the complex interplay between glacio eustatic sea level fluctuations the island s vertical motion trends the morphology of the shelf and the intensity of marine erosion subaerial terraces probably developed from 3 5 ma to 1 ma following a fortuitous conjugation of optimal exposure to energetic waves and a suitable arrangement lithology of the stratigraphic units promoting easier erosion their preservation was likely promoted by the uplift trend the island experienced in the last 3 5 ma which was rapid enough to prevent their destruction by subsequent highstands the submerged terraces presumably all younger than 1 ma were largely influenced by shelf gradient leading to more developed and preserved terraces in wider and low gradient sectors displacement by active faults also conditioned the formation and further development of both subaerial and submerged terraces with tectonic activity documented for the 0 693 ma 2 7 ma period

storm generated episodic sediment movements off kahe point oahu hawaii abstract the area off kahe point oahu hawaii has been the focus of recent oceanographic research in preparation for a large scale ocean thermal energy conversion otec project underwater instrument arrays moored to the bottom in this area were damaged shifted or lost during hurricane iwa in 1982 four underwater telephone cables located at greater depths were severed during the same period seamarc ii images show that most of the sea floor in this area is represented by light gray tones cores collected from this smooth sediment cover contain thick sequences of hemipelagic silt and clay darker acoustic reflection patterns trend downslope across this light gray background cores containing coarse sands and gravels and displaced shallow benthic foraminifera were collected from rough bottom represented by these patterns the pattern configurations sediment types within them and their benthic foraminiferal content indicate that these darker tones represent downslope sediment flow telephone cables were damaged and instrument arrays moved during hurricane iwa in places and along trajectories coincident with the orientation of the dark tones

assessing landslide movements in volcanic islands using near shore marine geophysical data south pico island azores marine geophysical data from around the submarine flanks of volcanic islands can potentially help to resolve whether large scale instability of an edifice has been geologically recently active we use geophysical data to investigate part of the coast of pico island of the azores where above sea level a major slump of topo volcano has been interpreted previously from arcuate escarpments and a rugged irregular topography seaward of them multibeam echo sounder data collected offshore of this feature show remarkably little evidence for slump fault movements in the island s submarine slope mid slope benches like those associated with the hilina slump of kilauea are absent the high resolution data extends onto the island s shelf allowing us to evaluate evidence for continuing activity there in particular as the shelf s rock platform will have been last modified by surf erosion during the postglacial period of sea level transgression it provides a reference surface of intermediate age 7 19 ka that can potentially reveal whether any movements occurred in pre historic times where the arcuate escarpments are continued offshore the modern seabed shows no bathymetric evidence for active faults where the shelf rock platform crops out in the multibeam data elsewhere mobile shelf sediments could be disguising evidence for active faulting so we examined boomer profiles able to image the rock platform beneath them the data reveal a platform that is steep 6 6 compared with the dips of platforms that we have studied previously around the coast of adjacent faial island and steeper than the platform outside the proposed slump this suggests that it was created by coastal erosion over a shorter period and hence is consistent with a younger age of the coastline as with the multibeam data where escarpments are continued offshore onto the shelf the rock surface imaged with these boomer data also shows no clear evidence of major slump related fault displacements this study therefore illustrates how high resolution boomer seismic and multibeam data could usefully contribute to hazard assessment of volcanic islands by helping to evaluate areas with no historical movements explanations to reconcile the onshore and offshore data here are also put forward

recent contributions to the climatology of the last glacial interglacial cycle based on french pollen sequences abstract new pollen data derived from three long french sequences and methodological improvements in the methods used to reconstruct past climates are summarized here after a short presentation of the study sites and pollen diagrams estimated climate parameters during the major episodes of the last 140 000 years are shown to be coherent between sites analysis of the seasonality variations provides much additional information in particular it is shown that the advection from the ocean has governed the last climatic cycle on the european continent

an analysis of eemian climate in western and central europe on the basis of 31 pollen diagrams and additional data for botanical macrofossils an analysis is made of the last interglacial eemian climatic history in western and central europe the main tool for this analysis is the climatic indicator species method only selected woody species are used for the quantification of data partial climatic range diagrams are presented for abies alba acer monspessulanum acer tataricum buxus sempervirens tilia tomentosa the problem of time correlation and pollen zonation of the eemian is discussed the climatic analysis itself is based on an improved version of the indicator species method in this version not every site is analysed for its climatic values instead maps and tables on the migrational history of hedera ilex buxus abies and species of acer tilia and abies are the basis for climatic maps showing respectively january and july isotherms for the periods of the corylus zone e4a and the carpinus zone e5 it is concluded that mean january temperatures were as much as 3 c higher at amsterdam the netherlands than at present and mean temperatures in july were 2 c higher however the thermal maximum in winter was later zone e5 than the summer thermal maximum zone e4a winter temperatures changed parallel to rise and fall of global sea level precipitation changes are more difficult to estimate in the first part of the eemian precipitation must have been relatively low but from zone e4b onward it increased to higher values reaching 800 mm and probably substantially more in zones e5 and e6 hence the eemian climate was in its beginning relatively more contintental and later from e4b onward more oceanic however as compared with the holocene the eemian climate was generally speaking more oceanic

was the climate of the eemian stable a quantitative climate reconstruction from seven european pollen records the aim of the present study is to estimate the range of the climatic variability during the eemian interglacial which lasted about 10 000 years marine isotopic stage 5e the modem pollen analogue technique is applied to seven high resolution pollen records from france and poland to infer the annual precipitation and the mean temperature of the coldest month the succession of pollen taxa and the reconstructed climate can be interpreted coherently the warmest winter temperatures are centred in the first three millennia of the eemian interglacial during the mixed oak forest phase with quercus and corylus as dominant trees a rapid shift to cooler winter temperatures of about 6 degrees to 10 degrees c occurred between 4000 and 5000 years after the beginning of the eemian related to the spread of the carpinus forest this shift is more obvious for the reconstructed temperatures than for precipitation and is unique and irreversible for the whole eemian period following this climatic shift of the eemian variations of temperature and precipitation during the fast 5000 years were only slight with an amplitude of about 2 degrees to 4 degrees c and 200 to 400 mm yr the estimated temperature changes were certainly not as strong as those reconstructed for the stage 6 5e termination or the transition 5e 5d this is consistent with the constantly high ratio of tree pollen throughout the eemian indicative of a succession of temperate forest types this gradual transition between different forest landscapes can be related to intrinsic competition between the species rather than to a drastic climatic change c 1998 elsevier science b v all rights reserved

radio and electrical measurements on glacial streams we discuss the suggestion that small under water transmitters might be used to illuminate the interior of major englacial water channels with radio waves once launched the radio waves would naturally tend to be guided along the channels until attenuated by absorption and by radiative loss receivers placed within the channels or at the glacier surface could be used to detect the signals they would provide valuable information about the connectivity of the water system the electrical conductivity of the water is of crucial importance a surface stream on storglachlren in sweden was found using a low frequency technique to have a conductivity of approximately 4 x 10 4 s m i although this is several hundred times higher than the conductivity of the surrounding glacier ice the contrast is not sufficient to permit us simply to use electrical con ductivity measurements to establish the connectivity of englacial water channels however the water conductivity is sufficiently small that under favourable circumstances radio signals should be detectable after travelling as much as a few hundred metres along an englacial water channel in a preliminary field experiment we demonstrated se mi quantitatively that radio waves do indeed propagate as expected at least in surface streams we conclude that under water radio transmitters could be of real practical value in the study of the englacial water system provided that sufficiently robust devices can be constructed in a subglacial channel however we expect the radio range would be much smaller the environment much harsher and the technique of less practical value

oceanography and patterns of shelf sediments mayaguez puerto rico abstract three rivers discharge onto the narrow insular shelf of mayaguez and anasco bays on the west coast of puerto rico the bays are bounded offshore by a discontinuous line of reefs the resulting pattern of carbonate and terrigenous sediments reflects both the source materials and the physical processes distributing sediments the carbonate sediments are found only near and on elevated reef structures terrigenous sediments are widely distributed and are encroaching over the coral reef areas a change in sediment distribution is occurring that will eventually result in loss of the reef environment except on the shelf edge this change is the result of increased sediment load in the rivers

imprints of volcanic erosional depositional tectonic and mass wasting processes in the morphology of santa maria insular shelf azores abstract the present day morphology of volcanic island shelves is the result of several factors namely the original shape and structure of the volcanic edifice the nature and age of the materials that compose its flanks and the erosional volcanic tectonic and sedimentary processes that acted to form these shelves by combining detailed seafloor mapping with onshore studies it is possible to gain a unique insight onto the evolution of volcanic island edifices and the processes that helped to shape their shelves here we look at santa maria island in the azores archipelago which is a 6 ma old ocean island volcano surrounded by a 135 km2 shelf characterized by an history of subsidence since its formation c 6 ma ago followed by uplift from 3 5 ma onwards by analyzing the geomorphic parameters of the insular shelf such as the shelf width and the erosive edge depth the island s history of vertical movements and by relating the morphology of the outcrops found on the shelf with those onshore we contribute to a better knowledge of the evolutionary history of santa maria with particular focus on its earlier stages of growth we infer that the outer part of the northern shelf is carved on units older than the oldest volcanic sequences exposed on land the western and southern shelves are almost entirely carved in the products of the oldest shield volcano anjos volcanic complex whilst the eastern shelf is the youngest in formation being related to units of the pico alto volcanic complex we also discuss the distribution of sediments on the shelf high wave energy concomitant with sea level drops contributed to the erosion and transport of older sequences offshore which were ultimately lost to the slopes of the island resulting in a shelf that is sediment stripped for the most part presently wide shelves further contribute to wave energy dissipation resulting in a significantly diminished sediment production the shelf edges around santa maria exhibit several erosive scars interpreted as the head of a submarine drainage network carved on the slopes of the island on the western southern and eastern shelves these mass wasting features are mostly controlled by tectonics since the extension of faults can be followed from onshore to the shelf edge on the northern shelf mass wasting appears to be mostly correlated with presence of unstable sediments on the shelf edge that triggered landsliding overall this work shows how detailed mapping of the shelves surrounding old volcanic islands can still provide important complementary information about the evolution of these islands which could not be acquired solely by the study of their subaerial and deeper submarine parts

combined flow origin of edgewise intraclast conglomerates sellick hill formation lower cambrian south australia unusually thick coarse grained edgewise intraclast conglomerates occur at eight or more horizons within subtidal nodular and ribbon bedded wackestones and packstones of the lower cambrian sellick hill formation south australia the intraclast beds are flat based and laterally discontinuous forming bar like structures that must have exhibited bathymetric relief of as much as 1 m the internal fabrics of these beds are variable thinner beds are dominated by flat lying intraclasts thicker beds contain both chaotic randomly oriented steeply inclined intraclasts and clusters of fan shaped vertically stacked edgewise intraclasts the sellick hill formation intraclast conglomerates are inferred to have been formed by intense storm generated combined flows on a broad subtidal carbonate ramp superimposition of wave induced oscillatory motions on geostrophic bottom flows during large storms generates short lived but exceptionally high instantaneous shear stresses in the bottom boundary layer entrainment of the relatively large intraclasts occurs through sliding rather than pivoting edgewise fabrics are a product of asymmetric acceleration and deceleration of intraclasts during passage of waves and the chaotic nature of collisions between intraclasts moving within the boundary layer collisions between intraclasts impart a rotating moment causing intraclasts to tip up during maximum fluid shear stress lodgement or packing of clasts in vertical or steeply inclined positions occurs within scours where intraclasts can wedge between other vertically inclined clasts or where intraclasts are pinned in steep orientations by collisions with shallowly inclined intraclasts differential erosional resistance of the intraclast deposits probably led to the development of sharp lateral changes in thickness the sellick hill formation intraclast conglomerates record erosion and reworking of subtidal subfairweather wave base environments by exceptionally intense and presumably rare storm flows the intraclast horizons represent a substantial loss in stratigraphic resolution due to widespread erosion of the ramp

the morphology of insular shelves as a key for understanding the geological evolution of volcanic islands insights from terceira island azores shelves from volcanic ocean islands result from the competition between two main processes wave erosion that forms and enlarges them and volcanic progradation that reduces their dimension in places where erosion dominates over volcanism shelf width can be used as a proxy for the relative age of the subaerial volcanic edifices and reconstruction of their extents prior to erosion can be achieved in this study new multibeam bathymetry and high resolution seismic reflection profiles are exploited to characterize the morphology of the insular shelves adjacent to each volcanic edifice of terceira island in order to improve the understanding of its evolution subaerial morphological and geological stratigraphic data were also used to establish the connection between the onshore and offshore evolution shelf width contiguous to each main volcanic edifice is consistent with the known subaerial geological history of the island most of the older edifices have wider shelves than younger ones the shelf edge proved to be a very useful indicator in revealing the original extent of each volcanic edifice in plan view its depth was also used to reconstruct vertical movements showing that older edifices like serra do cume ribeirinha guilherme moniz and pico alto have subsided while more recent ones have not the morphology of the shelf namely the absence presence of fresh lava flow morphologies and several types of erosional depositional and tectonic features integrated with the analysis of the coastline morphology allowed us to better constrain previous geological interpretations of the island evolution

palaeoecology of the pleistocene mis 5 5 outcrops of santa maria island azores in a complex oceanic tectonic setting abstract santa maria is the oldest island of the azores archipelago and the only one that possesses late miocene early pliocene and pleistocene fossils two pleistocene outcrops lagoinhas and prainha from the marine isotopic substage 5 5 mis 5 5 are known from santa maria island we studied the palaeoecology of the lagoinhas fossil assemblages and we also provide detailed lithological sections from both outcrops allowing for more detailed palaeoecological reconstruction ten bulk samples of approximately 1 kg each were collected from the sand facies at lagoinhas most of the gastropod taxa represented in these samples occur on the present azorean shores the exceptions being conus sp gibbula cf umbilicalis polynices lacteus and trachypolia nodulosa which have locally disappeared from the azorean malacofauna during the course of the last glaciation most of the fossil gastropods were epifaunal and crawlers about half of them were herbivores about one quarter was carnivores and only a few less than 10 were detritivores or parasites the preferred type of substrate was rocky substrate and or algae the palaeoecological evidence that results from the analysis of the fossiliferous beds the bioerosion structures the coralline algal and mollusc assemblages and their bathymetrical zonation suggests a marine environment depositional setting from shallow infralittoral shoreface to foreshore beach a single highstand episode including minor oscillations is apparent during mis 5 5 in the azores

calibration of the climatic signal in a new pollen sequence from la grande pile a new core gpxx from la grande pile vosges france has enabled a more precise evaluation of pollen data concerning the last climatic cycle at this site and has enabled reconstruction of the monthly temperature and precipitation this paper shows that the various components of the reconstructed climatic signal are clearly separated and that they are coherent with the vegetation dynamics the eemian interglacial was influenced first by an oceanic climate and second by a more continental one the two interstadials st germain i and ii were mainly continental these three temperate periods ended with a cool and humid transition period dominated by boreal forests which may have been favourable to ice accretion the dansgaard oeschger oscillations from 55 to 25 kyr bp are not significantly recorded in la grande pile

emergence and evolution of santa maria island azores the conundrum of uplifted islands revisited the growth and decay of ocean island volcanoes are intrinsically linked to vertical movements while the causes for subsidence are better understood uplift mechanisms remain enigmatic santa maria island in the azores archipelago is an ocean island volcano resting on top of young lithosphere barely 480 km away from the mid atlantic ridge like most other azorean islands santa maria should be experiencing subsidence yet several features indicate an uplift trend instead in this paper we reconstruct the evolutionary history of santa maria with respect to the timing and magnitude of its vertical movements using detailed field work and 40ar 39ar geochronology our investigations revealed a complex evolutionary history spanning 6 m y with subsidence up to ca 3 5 ma followed by uplift extending to the present day the fact that an island located in young lithosphere experienced a pronounced uplift trend is remarkable and raises important questions concerning possible uplift mechanisms localized uplift in response to the tectonic regime affecting the southeastern tip of the azores plateau is unlikely since the area is under transtension our analysis shows that the only viable mechanism able to explain the uplift is crustal thickening by basal intrusions suggesting that intrusive processes play a significant role even on islands standing on young lithosphere such as in the azores

a budget of carbonate framework and sediment production kailua bay oahu hawaii abstract sediments of the bay and coastal plain of kailua oahu hawaii are 90 biogenic carbonate produced by destruction of primary reef framework coral and encrusting coralline algae and by direct sedimentation through the biological activity of calcifying organisms the green alga halimeda the branching coralline alga porolithion gardineri molluscs and benthic foraminifera field measurements of benthic community structure gross carbonate production bioerosion and direct sedimentation in 17 physiographic zones in kailua bay are used to calculate modern calcareous sediment production rates in the 12 km2 fringing reef system total gross carbonate productivity by corals and encrusting coralline algae based on mapped percent cover and known growth rates occurs at an average rate of 1 22 0 36 kg m 2 y 1 over hard substrates of the reef platform corresponding to 0 8 0 2 mm y 1 using a bulk density of 1 48 g cm 3 the average of coral and coralline algae coralline algae contributes 42 of the total gross productivity bioerosion of coral and coralline algae facies at and near the reef surface estimated from slabbed reef samples occurs at average rates of 0 10 1 15 kg m 2 y 1 and releases 1 911 436 m3 of unconsolidated carbonate sediment annually mechanical erosion coral breakage likely contributes an additional 315 m3 y 1 carbonate sediment is also produced directly by the green alga halimeda branching coralline algae molluscs and benthic foraminifera at a combined rate of 1 822 200 m3 y 1 using densities specific to sediment origin the total rate of production of unconsolidated carbonate sediment in kailua bay is the sum of these sources amounting to 4 048 635 m3 y 1 normalizing gross sediment production in kg y 1 by reef habitat area in m2 generates average rates of productivity in kg m 2 y 1 that are directly comparable to each other and to the literature such rates can also be employed and tested in other reef settings in kailua bay the total production of calcareous sediment corresponds to an average normalized rate of 0 53 0 19 kg m 2 y 1 with 0 33 0 13 kg m 2 y 1 contributed through erosion of the coralgal framework and 0 20 0 06 kg m 2 y 1 contributed by direct sediment production on the reef surface applying these modern sediment production rates over the 5 000 years that kailua bay has been completely inundated by postglacial sea level rise an estimated 20 2 3 2 106 m3 of unconsolidated carbonate sediment has been produced in the system the volume of sediment stored in the various reef channels and holes in kailua bay is 3 7 0 3 106 m3 or 19 of that produced since 5 000 y bp the volume of sand in the modern beach is 1 0 0 1 106 m3 or 5 of holocene sediment production the volume of carbonate sediment stored in the coastal plain is estimated using core log data and associated radiocarbon ages to be 10 0 1 8 106 m3 or 51 of holocene sediment production the remaining 25 likely represents sediment loss due to the natural processes of dissolution attrition and transport offshore these export terms are not well understood and emphasize the need for sediment dynamics to be incorporated into reef and sediment budgets although sediment production in this reef system is prodigious the rate of new sediment supplied to the beachface is less than 2 of what moves on and off the beach seasonally

gravitational erosional sedimentary and volcanic processes on the submarine environment of selvagens islands madeira archipelago portugal abstract volcanic oceanic islands are the emerged portions of large volcanoes that rise abruptly from the ocean floor although the geological record of these islands provide some insights into the evolution of their entire volcanic edifices for a complete picture it is essential to study the islands submarine pedestals and surrounding settings in this study we document the submarine morphology of the selvagens islands madeira archipelago portugal and relate it with their subaerial evolution in order to gain a more complete insight on the evolutionary history of these islands to this purpose we employed bathymetric surfaces backscatter mosaics and subbottom profiler data integrated with geological observations of the subaerial part of the islands our study reveals the presence of a complex submarine morphology composed mainly of two deeply eroded central volcanoes the edifices of selvagem grande and selvagem pequena and a less eroded saddle like ridge related to a fissural volcanic system located between them other secondary landforms generated by volcanism erosion gravitational collapses and possible faulting activity are also present whilst the building of the two central volcanoes relates to the older volcanic stages of both islands the fissural system with a general ne sw trend is probably contemporaneous of the younger volcanic stages of selvagem grande the shelf of selvagem grande also features the eroded remains of numerous relatively young volcanic cones seemingly forming several nw se and ne sw lineaments the same direction observed onshore for the younger volcanic stage of this edifice the shelves break of both selvagens was affected by multiple landslide scars and channel headwalls the channels constitute a large drainage network that fans out in a radial pattern along the flanks of both central edifices in the deeper parts of this submarine drainage large sediment wave fields are observed in some locations with wavelengths of 300 1 900 m and 2 45 m in height these tend to form cyclic steps that change gradually downslope to antidunes and their origin is attributed to sediment density flows that suffer hydraulic jumps when their channel confinement ends and the slope gradient decreases from 7 to 2 5 several scour features are also found at 3 300 4 000 m water depth being 3 20 km in width 10 20 km in length rectangular or u shaped in cross section and 40 100 m deep they occur around the base of the submarine edifices where seafloor gradients change to 3 0 0 5 their origin is also related to hydraulic jumps of unconfined sediment density flows which are able to erode the seafloor and create these features these morphologies are a testimony to how volcanic erosional and depositional processes conjugate to shape the flanks of a very long lived volcanic island system one of the oldest in the north atlantic ocean

eemian and early weichselian temperature and precipitation variability in northern germany abstract dramatic changes in european vegetation occurred during the transition from the eemian interglacial to weichselian glacial climates correlative with major changes in global ice core and marine records quantitative knowledge of climate change is important for understanding of the climate system and for climate modelling for which reconstructions of this transitional period are of special interest however it has been difficult to quantify the climatic changes involved in the eemian to early weichselian transition from terrestrial archives due to the lack of modern vegetation analogues to circumvent this problem we applied a suitable multivariate probabilistic approach to pollen and plant macrofossil assemblages to reconstruct temperature and precipitation for this transition in central europe our reconstructions span the interval from the beginning of the eemian marine isotope stage mis 5e to the odderade interstadial mis 5a they indicate a relatively stable eemian with increasing precipitation reducing the continentality of the climate with time during the transition from the eemian to the herning stadial mean july and january temperatures decreased by 4 c and by as much as 20 c respectively temperatures remained high enough to support forests during the stadials and we infer that the reconstructed decrease of precipitation below 500 mm per year caused the extirpation of forests during these periods thus we conclude that precipitation although difficult to reconstruct is of vital importance for explaining vegetation change during the eemian and eemian early weichselian transition

sedimentology of rocky shorelines 1 a review of the problem with analytical methods and insights gained from the hulopoe gravel and the modern rocky shoreline of lanai hawaii abstract hypotheses advanced concerning the origin of the pleistocene hulopoe gravel on lanai include mega tsunami abandoned beach multiple event rocky shoreline and for parts of the deposit native hawaiian constructions and degraded lava flow fronts uplift of lanai shorelines has been suggested for deposits occurring up to at least 190 m these conflicting hypotheses highlight problems with the interpretation of coarse gravel deposits containing marine biotic remains the geological records of the processes implied by these hypotheses should look very different discrimination among these or any other hypotheses for the origins of the hulopoe gravel will require careful study of vertical and lateral variations in litho and biofacies facies architecture contact relationships and stratal geometries of this deposit observations of modern rocky shorelines particularly on lanai adjacent to hulopoe gravel outcrops have shown that distinctive coarse gravel facies are present several of which occur in specific geomorphic settings tectonic isostatic and eustatic changes which cause rapid shoreline translations on steep slopes favour preservation of former rocky shorelines and associated sedimentary deposits both above and below sea level the sedimentary record of those shorelines is likely to be complex the modern rocky shoreline sedimentary environment is a hostile one largely neglected by sedimentologists a range of high energy processes characterize these shorelines long period swell tsunami and storm waves can erode hard bedrock and generate coarse gravel they also erode older deposits depositing fresh ones containing mixtures of materials of different ages additional gravelly material may be contributed by rivers draining steep hinterlands to fully evaluate rocky shoreline deposition in the broadest sense for both the hulopoe gravel and other deposits sedimentary facies models are needed for rocky shorelines occurring in a range of settings recognition and description of rocky shoreline deposits are crucial for correctly interpreting the geological history of oceanic and volcanic arc islands for distinguishing between ancient tsunami and storm deposits and for interpreting coarse grained deposits preserved on high energy coasts of continents problems include not only the absence of appropriate sedimentary facies models linking rocky shoreline deposits and environments but also until recently lack of a systematic descriptive scheme applicable to coarse gravel deposits generally two complementary methods serve to integrate the wide range of bed and clast attributes and parameters which characterize complex coarse gravel deposits the composition and fabric caf method has a materials focus providing detailed description of attributes of the constituent clasts petrology the proportions of gravel sand and mud and the ways in which these materials are organized the sedimentary facies model building fmb method emphasizes the organization of a deposit on a bed by bed basis to identify facies and infer depositional processes the systematic use of a comprehensive gravel fabric and petrography log gfpl in conjunction with detailed vertical profiles provides visual representations of a range of deposit characteristics criteria useful for distinguishing sedimentary facies in the hulopoe gravel are grain size modes amount of matrix bed geometry sedimentary structures bed fabric and clast roundness

stable climatic conditions in central germany during the last interglacial stable isotopic data from the high resolution limnic sequence in the opencast mine at grobern central germany confirm the relatively stable climate of the last interglacial deduced from pollen analyses after significant warming during the transition from the saalian to the eemian stable warm climatic conditions set in once the climatic optimum was reached in the course of biozones e4 to e5 from the middle of biozone e6b a gradual temperature decrease can be observed reaching a minimum at the start of biozone e7 the division of the early weichselian glacial in central germany into two stadials herning rederstall and two interstadials brorup odderade is also documented by the findings copyright 2000 john wiley sons ltd

morphology of the faial island shelf azores the interplay between volcanic erosional depositional tectonic and mass wasting processes 1 the extents of volcanic island shelves result from surf erosion which enlarges them and volcanic progradation which reduces them however mass wasting tectonics and sediment deposition also contribute to their morphology in order to assess the relative significance of these various processes we have mapped in detail faial island s shelf in the azores archipelago based on interpretation of geophysical and geological data the nearshore substrates of the island down to 30 50 m depth are rocky and covered by volcaniclastic boulder deposits formed by surf action on now submerged lava flows below those depths sandy and gravel volcaniclastic beds dominate building clinoforms up to the shelf edge in some sectors of the coast prograding lava has narrowed the shelf but in contrast to nearby pico island we find fewer submarine emplaced lavas on the shelf in this island we interpret the distance between the coastline and the shelf edge as almost entirely a result of a straightforward competition between surf erosion and lava progradation in which erosion dominates therefore shelf width can be used as a proxy for coastline age as well as for wave energy exposure the stratigraphy of shelf deposits in boomer seismic data is examined in detail to assess the roles of different sediment sources accommodation space and wave exposure in creating these deposits we also show evidence of mass wasting at the shelf edge and discuss the possible origins of slope instability finally we discuss the contributing role of tectonics for the development of the shelf

comparing historic records of storm frequency and the north atlantic oscillation nao chronology for the azores region the storminess of the azores region was investigated using newspaper records from ad 1836 onwards the information obtained was rank ordered for intensity and the time series of storm frequency ana

reply to comment by marques et al on the insular shelves of the faial pico ridge azores archipelago a morphological record of its evolution

depositional processes on oceanic island shelves evidence from storm generated neogene deposits from the mid north atlantic oceanic islands such as the azores in the mid north atlantic are periodically exposed to large storms that often remobilize and transport marine sediments along coastlines and into deeper environments such disruptive events create deposits denominated tempestites whose characteristics reflect the highly dynamic environment in which they were formed tempestites from oceanic islands however are seldom described in the literature and little is known about storm related sediment dynamics affecting oceanic island shelves therefore the geological record of tempestite deposits at oceanic islands can provide invaluable information on the processes of sediment remobilization transport and deposition taking place on insular shelves during and after major storms in santa maria island azores a sequence of neogene tempestite deposits was incorporated in the island edifice by the ongoing volcanic activity thus preserved and later exposed through uplift and erosion because it was overlain by a contemporary coastal lava delta the water depth at the time of deposition could be inferred constituting an excellent case study to gain insight on the still enigmatic processes of insular shelf deposition sedimentological palaeontological petrographic and palaeo water depth information allowed the reconstruction of the depositional environment of these sediments the sequence typifies the characteristics of a tempestite or successive tempestites formed at ca 50 m depth in a steep energetic open insular shelf and with evidence for massive sediment remobilization from the nearshore to the middle or outer shelf the authors claim that cross shelf transport induced by storm events is the main process of sediment deposition acting on steep and narrow shelves subjected to high energetic environments such as the insular shelves of open sea volcanic islands

development of volcanic insular shelves insights from observations and modelling of faial island in the azores archipelago a variety of geological processes contribute to the development of volcanic island shelves although their relative importance remains unclear we have mapped the morphology of faial island s shelf in the azores from geophysical multibeam sonar chirp and boomer seismic reflection and geological data sediment sampling a wave erosional model and a eustatic record of glacially induced oscillations of sea level which modulated the elevation at which the waves operated through time was used to determine the contribution of mechanical wave erosion to shelf development wave regimes varied according to the orientation of the coast the model was run for 10 to 800 ka depending on the age of the various coastal sectors based on published radiometric data the modelling replicated the shape of the island s shelf reasonably well supporting the contention that it developed primarily through mechanical wave erosion operating in an intertidal zone that migrated landwards and seawards with changes in the level of the sea disparities between modelled and actual shelf morphologies may reflect varied geological resistance to erosion errors in the radiometric dates more recent unrecognised volcanic deposits sediment deposition and tectonic vertical movements there were some variation in rates of shelf development over different time scales but over the long term the relationship between shelf age and width was essentially linear the depth of the shelf break in some areas suggests that there have been differential vertical movements of the land around the island probably related to local faults the poor development or absence of terraces on the shelf may be attributed either to recent volcanic progradation or to sediment infilling of the space created by earlier erosion however poorly developed terraces on the southern shelf of faial are similar to those predicted by the model given appropriate adjustments for vertical movements of the land

gravitational erosional and depositional processes on volcanic ocean islands insights from the submarine morphology of madeira archipelago abstract the submarine flanks of volcanic ocean islands are shaped by a variety of physical processes whilst volcanic constructional processes are relatively well understood the gravitational erosional and depositional processes that lead to the establishment of large submarine tributary systems are still poorly comprehended until recently few studies have offered a comprehensive source to sink approach linking subaerial morphology with near shore shelf slope and far field abyssal features in particular few studies have addressed how different aspects of the subaerial part of the system island height climate volcanic activity wave regime etc may influence submarine flank morphologies we use multibeam bathymetric and backscatter mosaics of an entire archipelago madeira to investigate the development of their submarine flanks crucially this dataset extends from the nearshore to the deep sea allowing a solid correlation between submarine morphologies with the physical and geological setting of the islands in this study we also established a comparison with other island settings which allowed us to further explore the wider implications of the observations the submarine flanks of the madeira archipelago are deeply dissected by large landslides most of which also affected the subaerial edifices below the shelf break landslide chutes extend downslope forming poorly defined depositional lobes around the islands a large tributary system composed of gullies and channels has formed where no significant rocky ridge outcrops are present in madeira island these were likely generated by turbidity currents that originated as hyperpycnal flows whilst on porto santo and desertas their origin is attributed to storm induced offshore sediment transport at the lower part of the flanks 3000 to 4300 m where seafloor gradients decrease to 0 5 3 several scour and sediment wave fields are present with the former normally occurring upslope of the latter sediment waves are often associated with the depositional lobes of the landslides but also occur offshore poorly developed tributary systems sediment wave fields and scours are mostly absent in areas where the tributary systems are well developed and or are dominated by rocky outcrops this suggests that scours and sediment wave fields are probably generated by turbidity currents which experience hydraulic jumps where seafloor gradients are significantly reduced and where the currents become unconfined the largest scours were found in areas without upslope channel systems and where wave fields are absent and are also interpreted to have formed from unconfined turbidity currents our observations show that tributary systems are better developed in taller and rainy islands such as madeira on low lying and dry islands such as porto santo and desertas tributary systems are poorly developed with unconfined turbidite currents favouring the development of scours and sediment wave fields these observations provide a more comprehensive understanding of which factors control the gravitational erosional and depositional features shaping the submarine flanks of volcanic ocean islands

interpretation of radio echoes from storglaciaren northern sweden analyse des echos d ondes metriques et decimetriques a l aide d une theorie d onde scalaire de la diffraction et d une statistique simple on peut par exemple etudier les rugosites du lit et les orientations des diffuseurs a l interieur de la glace

neogene marine sediments and biota encapsulated between lava flows on santa maria island azores north east atlantic an interplay between sedimentary erosional and volcanic processes

increased seasonality in middle east temperatures during the last interglacial period the last interglacial period about 125 000 years ago is thought to have been at least as warm as the present climate owing to changes in the earth s orbit around the sun it is thought that insolation in the northern hemisphere varied more strongly than today on seasonal timescales which would have led to corresponding changes in the seasonal temperature cycle here we present seasonally resolved proxy records using corals from the northernmost red sea which record climate during the last interglacial period the late holocene epoch and the present we find an increased seasonality in the temperature recorded in the last interglacial coral today climate in the northern red sea is sensitive to the north atlantic oscillation a climate oscillation that strongly influences winter temperatures and precipitation in the north atlantic region from our coral records and simulations with a coupled atmosphere ocean circulation model we conclude that a tendency towards the high index state of the north atlantic oscillation during the last interglacial period which is consistent with european proxy records contributed to the larger amplitude of the seasonal cycle in the middle east

palaeoecology taphonomy and preservation of a lower pliocene shell bed coquina from a volcanic oceanic island santa maria island azores abstract massive fossil shell accumulations require particular conditions to be formed and may provide valuable insights into the sedimentary environments favouring such concentrations shallow water shell beds appear to be particularly rare on reefless volcanic oceanic islands on account of narrow steep and highly energetic insular shelves where the potential for preservation is limited the occurrence of an exceptional coquina pedra que pica within the miocene pliocene deposits of santa maria island azores therefore provides a rare opportunity to understand the conditions that led to the formation and preservation of a massive shell bed at mid ocean insular setting this study provides a detailed analysis regarding a 10 11 m thick bivalve dominated fossil assemblage exposed at pedra que pica on santa maria island in the azores integration of taphonomical palaeoecological and sedimentological observations are used to reconstruct the genesis of the coquina bed and related events and to discuss why such exceptional sedimentary bodies are so rare on shelves around reefless volcanic oceanic islands the sequence at pedra que pica demonstrates a complex succession of sedimentary environments in response to the drowning of an existing coastline during a period of rapid sea level rise the pedra que pica shell bed incorporates storm related materials and possible debris falls that originated nearby in a shallow and highly productive carbonate factory deposition took place below fair weather wave base at around 50 m depth as inferred from the overlying volcanic succession the preservation of this coquina was favoured by deposition on a platform laterally protected by a rocky spur combined with rapid burial by water settled volcanic tuffs and subsequent volcanic effusive sequences the recent exhumation of the deposit is the result of island uplift and subsequent erosion

a review of the mis 5e highstand deposits from santa maria island azores ne atlantic palaeobiodiversity palaeoecology and palaeobiogeography abstract the privileged location of santa maria island azores archipelago in the middle of the north atlantic makes the fossiliferous outcrops on this island of utmost importance to gain a better understanding of how coeval living communities relate to the broader evolutionary and biogeographic history of the atlantic basin during the late neogene and the quaternary here we focus on this island s mis 5e fossil record offering a comprehensive review on the palaeobiodiversity palaeoecology and palaeobiogeography of the biota living in the mid north atlantic during this interglacial several studies in oceanic islands stress the huge impact of sea level changes on insular communities pleistocene sea level changes occur during the short time events known as terminations associated to glacial interglacial shifts as well as with the onset of glaciations associated to interglacial glacial shifts both are responsible for extinctions and local disappearance of species bottleneck effects and formation of new species resulting in community structure changes this work increases the number of fossil marine taxa reported from the last interglacial deposits of santa maria to 143 species all the 19 new records are molluscs 13 gastropods and 6 bivalves thus increasing the number of fossil molluscs to 136 species although thermophilic members of the senegalese tropical fauna were found in these deposits many of the most emblematic species e g persististrombus latus strombus bubonius cymbula safiana harpa doris cardita senegalensis barbatia plicata ctena eburnea or hyotissa hyotis are absent suggesting that they did not reach the azores our results indicate that the main differences between the species composition of the mis 5e and the present day shallow water azorean communities are probably due to the dropping of sea surface temperature associated with the onset of the last glaciation which had both direct and indirect effects on species ecology a group of 21 thermophilic species was directly affected by the lower sea surface temperature whereas a group of four sand associated species was indirectly but similarly affected by the lowering of the sea level both groups have locally disappeared from the azores however none of the extant endemic species found on the studied mis 5e outcrops was apparently affected by the lowering sst in contrast to the biogeographical relationships of the recent azorean shallow marine molluscs which are predominantly with the mediterranean region portugal and with the madeira and canary islands archipelagos the palaeobiogeographical relationships of the mis 5e azorean marine molluscs are mainly with canaries and west africa despite the general low similarity of the biogeographical relationships between the azores and cape verde archipelago on both the recent and the mis 5e analysis this similarity is nevertheless higher for the mis 5e mollusc assemblages emphasizing the role of cape verde as an important source of warm water species during the last interglacial

estimating palaeo water depth from the physical rock record abstract palaeo water depth and its change with time is a key factor in environmental analysis and in sedimentology in general the literature published on this topic and on related subjects however is substantial albeit scattered within and between different communities geologists oceanographers engineers physicists etc here i focus on proxies for palaeo bathymetry as obtained from the physical rock record floral faunal and chemical evidence for palaeo water depth being equally important must be dealt with elsewhere an assessment of the main depth related parameters in actualistic settings is presented and their applicability to the fossil sedimentary record discussed the outcome reveals the full complexity of this topic there is for example no such thing as an average wave base depth applicable to a wide range of fossil case settings this because wave and current climates in general and particularly so in neritic and coastal settings are intriguingly complex furthermore observations from modern oceans are not a priori applicable to fossil ones acknowledging these problems and limitations critically evaluated quantitative proposals for depth indicative facies and features in the sedimentary record are presented and error bars discussed

boundary layer dynamics and sediment transport under storm and non storm conditions on the scotian shelf abstract near bed measurements of waves currents seabed responses and ripple migration rates were obtained using an instrumented tripod at a water depth of 39 m on the scotian shelf during the winter of 1992 93 these data and the grant and madsen s 1986 grant w d madsen o s 1986 the continental shelf bottom boundary layer annu rev fluid mech 18 265 305 combined flow boundary layer model are used to examine wave current interaction various sediment dynamic thresholds and sediment transport on an exposed high energy continental shelf the seabed was found to be rippled for most time of the deployment and thus the ripple enhanced combined skin friction shear velocity had to be used to determine the initiation of bedload transport under combined flows this indirectly indicates adequate predictions of the skin friction shear velocities inside the wave boundary layer by the grant and madsen model at high transport stages bedload roughness must be added to the grain size roughness to obtain a transportrelated combined shear velocity in order to predict correctly the onsets of saltation suspension and sheet flow transports otherwise the initiation of suspended load transport and the total sediment transport rates will be severely under estimated the comparison between the prediction by the grant and madsen 1986 model and the calculation of a quadratic stress law suggests that the total current shear velocity was enhanced by a factor of 2 3 due to the wave current interaction during storms while the apparent bottom roughness was increased by more than an order of magnitude the non linear coupling between waves and currents also causes a 20 increase of the combined skinfriction shear velocity inside the wave boundary layer this non linear coupling is most important when waves and currents are roughly equal in magnitude and the angles between them are less than 30 four sediment transport formulae were tested while the engelund hansen total load and yalin bedload methods did not perform well the einstein brown and bagnold formulae were found to respectively give reasonable predictions of the bedload and total load sediment transport rates under the observed combined flow conditions the predicted sediment transport direction is also in good agreement with the observed ripple migration direction the gsc sediment transport model sedtrans92 predicts that the net daily transport rates during the storms reached 822 kg m 1 day 1 and were 2 3 orders of magnitude higher than the non storm transport suggesting the dominance of storm processes in sediment transport on the scotian shelf these values are in good agreement with the results from sand tracer experiments conducted in this region we thus conclude that sedtrans92 can properly simulate boundary layer dynamics and sediment transport on continental shelves

the last climatic cycle at la grande pile vosges france a new pollen profile a new pollen diagram has been made from an old unanalyzed core from la grande pile gp xx correlations with the previous work of woillard 1975 1978 leads to the following conclusions the end of the eemian was marked by a minor climatic change prior to the melisey i stadial the ognon ii and ognon iii interstadials are not consistent and correspond to the level of reworking of mesophilous taxa during the last pleniglacial the limitations of the botanical interpretation of pollen spectra from the last pleniglacial are underlined lastly bruckenthalia and larix are identified for the first time at la grande pile the respective roles of these taxa following the eemian are additional arguments for correlating the st germain i and ii with the early weichsel interstadials in the north of middle europe

vegetation and climate in the early and pleni weichselian in northern central europe analysis of numerous pollen diagrams from north and central germany and from the adjacent lowlands of the netherlands denmark poland and belarus have facilitated a regional comparison of the vegetation and climatic evolution from the beginning of the early weichselian glaciation to the weichselian pleniglacial data from geological studies and analysis of fossil beetles and plant macroremains have been used to supplement the palaeoclimatic reconstruction up to the end of the oerel interstadial the palaeoclimate was characterised by increasing continentality the winter temperatures in particular tended to fall continuously during the stadials and the interstadials of the early weichselian and early pleniglacial in the brorup and odderade interstadials summer temperatures where sufficiently high to enable boreal forests to grow whereas in the oerel interstadial summer temperatures were such that tree growth was inhibited it is probable that falling sea level and the consequent extension northwards of the north sea coast were the main causes of increasing continentality in the latter part of the pleniglacial peat accumulation frequently took place and humic silts were deposited under lacustrine conditions correlation between various sites is extraordinarily difficult pollen diagrams from the so called interstadials of the glinde moershoofd complex hengelo and denekamp are similar to those of the known early weichselian stadials it is proposed therefore that these interstadials should be called intervals and that the term interstadial be reserved for climatic variations that result in distinctive pollen assemblages and which in turn reflect distinctive vegetation dynamics interstadials should be capable of being characterised on a biostratigraphical basis and it should be possible to establish correlations over considerable distances according to this definition the first three warm oscillations of the weichselian glaciation in the central european lowlands are the brorup odderade and oerel interstadials all other pleniglacial peat layers should be assigned the rank of interval copyright 2001 john wiley sons ltd

new k ar ages chemical analyses and magnetic data of rocks from the islands of santa maria azores porto santo and madeira madeira archipelago and gran canaria canary islands k ar determinations major and trace element chemical analyses and magnetic data are reported for rocks from santa maria azores madeira and porto santo and gran canaria based on these data the age of the basement of santa maria is believed to have formed between about 5 2 and 4 6 m y the unconformably overlying pillow complex interbedded with fossiliferous calcarenites about 3 8 to 3 3 m y with the capping subaerial basalt being part of the same magmatic phase the major erosional phase levelling the basement is thus approximately synchronous with the major pliocene regression r2 on gran canaria lietz andschmincke 1975 possibly indicating a widespread eustatic event the upper part of the submarine partly fossiliferous series of porto santo was dated as ca 12 to 13 m y and the quaternary age for the major basalt formation in eastern madeira watkins andabdel monem 1971 is confirmed the ages of several formations on gran canaria were slightly revised

persististrombus coronatus mollusca strombidae in the lower pliocene of santa maria island azores ne atlantic paleoecology paleoclimatology and paleobiogeographic implications abstract the family strombidae is one of the twenty three families and subfamilies of gastropods associated with tropical environmental conditions and therefore useful as a biogeographical and paleoclimatic proxy today the strombid genus persististrombus is represented in the ne atlantic by a single species restricted to the tropical mauritanian senegalese province this work reports the occurrence of persististrombus coronatus from the lower pliocene of santa maria island in the azores archipelago based on this occurrence and on the mio pliocene fossil record of the ne atlantic oceanic islands paleoclimatological considerations are discussed which allow for the first time to include the azores and the other macaronesian islands in a wider context of the ne atlantic paleobiogeographical molluscan provinces late miocene to present day molluscan biogeographic units ranging in latitude from 60 n down to 17 s are here defined and the boundaries of the proposed climatic zones are outlined we suggest that during the upper miocene lower pliocene the paleoclimate at santa maria island was drastically different from that seen at those latitudes today with mean annual sea surface temperatures ssts about 3 7 c to 6 3 c higher than the present day 20 6 c and with mean monthly ssts ranging from 20 c to 28 c with six months with mean ssts over 24 c conditions typical of a tropical setting

evidence for general instability of past climate from a 250 kyr ice core record recent results1 2 from two ice cores drilled in central greenland have revealed large abrupt climate changes of at least regional extent during the late stages of the last glaciation suggesting that climate in the north atlantic region is able to reorganize itself rapidly perhaps even within a few decades here we present a detailed stable isotope record for the full length of the greenland ice core project summit ice core extending over the past 250 kyr according to a calculated timescale we find that climate instability was not confined to the last glaciation but appears also to have been marked during the last interglacial as explored more fully in a companion paper3 and during the previous saale holstein glacial cycle this is in contrast with the extreme stability of the holocene suggesting that recent climate stability may be the exception rather than the rule the last interglacial seems to have lasted longer than is implied by the deep sea specmap record4 in agreement with other land based observations5 6 we suggest that climate instability in the early part of the last interglacial may have delayed the melting of the saalean ice sheets in america and eurasia perhaps accounting for this discrepancy

a budget of marine and terrigenous sediments hanalei bay kauai hawaiian islands abstract the sediment budget of hanalei bay on the north shore of kauai was calculated using sedimentological and geophysical methods the calculations of the budget subsequently allowed an interpretation of the holocene history of the bay the bay sediments are easily separated into marine carbonate and terrigenous siliciclastic grains surficial sediments are dominated by carbonate grains 70 of coralline algae coral and mollusc fragments as well as foraminifera halimeda bryozoa and echinoderm tests however siliciclastic grains e g olivine plagioclase volcanic lithics from the hanalei river watershed draining shield volcanic highlands are the most common individual grain type 27 and form a zone of high concentration from the mouth of the hanalei river into the center of the bay flooding in the bay by the post glacial sea level rise began soon after 11 7 kyears the resulting marine environment caused the net deposition of 45 5 1 5 10 6 m 3 of sediment in the bay and approximately 33 7 11 2 10 6 m 3 of sediment on the hanalei coastal plain the total volume of carbonate sediment stored in the bay and coastal plain is greater than the volume likely to have been produced exclusively within the bay during the same time calculations indicate that approximately 2490 m 3 year 1 have been imported into the bay or coastal plain and deposited since 11 700 years ago the majority of this sediment influx is likely delivered from the east by the strong tradewind driven littoral currents that characterize kauai s north shore net carbonate sediment deposition in hanalei bay peaked at a rate of 15 500 m 3 year 1 between 5000 and 3000 years ago when sea level may have been 2 m above present diminishing to 3890 m 3 year 1 from 1000 years ago to the present this influx is likely to have played a significant role in the mid to late holocene progradation of the hanalei shoreline

miocene pliocene rocky shores on sao nicolau cape verde islands contrasting windward and leeward biofacies on a volcanically active oceanic island abstract north atlantic islands in the cape verde archipelago off the coast of west africa commonly feature an elongated n s shape in which reduced northern coasts and longer eastern shores absorb the brunt of wave activity and long shore currents generated by prevailing north east trade winds located in the middle windward islands sao nicolau is unusual in profile with an elongated e w configuration that offers a broad target against high energy wind driven waves conversely the south shore of sao nicolau provides relatively wide shelter in a leeward setting reconstruction of the proto island prior to the onset of the main eruptive stage during the late miocene at 5 1 ma reveals a moderately smaller island with essentially the same e w orientation this study combines previous data with results from a detailed stratigraphic log based on upper miocene limestone deposits on the island s south flank for comparison with stratigraphic profiles of upper miocene limestone from the island s northeast quarter logs from a pliocene sandy limestone outcropping on the south central coast of sao nicolau give added context to the diversity of marine invertebrates including branching coral colonies and delicate ramose bryozoans that found shelter in a leeward setting whole rhodoliths contribute the main fabric of carbonates deposited against rocky shores on the northern exposed side of the miocene island whereas only traces of worn rhodoliths and rhodolith sand occur as in finer miocene grainstone on the island s southern protected side miocene and pliocene carbonate deposits were terminated by submarine flows on an actively growing volcanic island the passage zone from submarine to subaerial flows on the island s flanks makes a useful meter stick to gauge absolute water depth at the moment of local extinction by volcanic activity

modern rhodoliths from the insular shelf of pico in the azores northeast atlantic ocean abstract a seabed sediment sampling survey conducted on the pico insular shelf found abundant rhodoliths between 64 and 73 m off the south coast of the island these were small and mainly ellipsoidal in shape with a maximum diameter of 3 75 cm granules and small pebbles of eroded basalt were also a typical component of these samples thin algal crusts were secreted on basalt pebbles by the coralline red algae phymatolithon calcareum which in turn were covered by lithophyllum incrustans additional samples were collected by snorkelling at mare lajes do pico a shallow lagoon 2 4 m in depth on the south coast here rhodoliths are mostly spheroidal and bigger maximum diameter of 4 75 cm formed by thin thalli of p calcareum based on these results distribution of shapes and species and previous work on the characteristics of fossil specimens from neogene deposits on santa maria island azores and other north atlantic archipelagos an empirical depositional model is proposed for the development of rhodoliths on the pico island shelf 1 nearshore rhodoliths formed solely by p calcareum are subjected to a wide range of currents and waves resulting in their spheroidal shapes however those of mare lagoon are protected from offshore transport and tend to grow larger than deep water rhodoliths 2 although not sampled there must be middle shelf rhodoliths formed solely by p calcareum that tend to form more ellipsoidal shapes due to seafloor oscillatory movements caused by waves crossing the shelf 3 during storms these middle shelf rhodoliths are then transported to the outer shelf where l incrustans overgrows the initial cover of p calcareum shallow associations are normally larger reflecting therefore a longer life span than the deeper associations transport by storms appears to be an important factor in the formation of some deep water rhodoliths around volcanic oceanic islands subjected to high wave energy however their exposure to an energetic environment and likely frequent offshore transport does not allow them to grow as large as those from shallow water

coastal evolution on volcanic oceanic islands a complex interplay between volcanism erosion sedimentation sea level change and biogenic production abstract the growth and decay of oceanic hotspot volcanoes are intrinsically related to a competition between volcanic construction and erosive destruction and coastlines are at the forefront of such confrontation in this paper we review the several mechanisms that interact and contribute to the development of coastlines on oceanic island volcanoes and how these processes evolve throughout the islands lifetime volcanic constructional processes dominate during the emergent island and subaerial shield building stages during the emergent island stage surtseyan activity prevails and hydroclastic and pyroclastic structures form these structures are generally ephemeral because they can be rapidly obliterated by marine erosion with the onset of the subaerial shield building stage coastal evolution is essentially characterized by rapid but intermittent lateral growth through the formation of lava deltas largely expanding the coastlines until they typically reach their maximum extension with the post shield quiescence in volcanic activity destructive processes gradually take over and coastlines retreat adopting a more prominent profile mass wasting and marine and fluvial erosion reshape the landscape and if conditions are favorable biogenic processes assume a prominent role post erosional volcanic activity may temporarily reverse the balance by renewing coastline expansion but islands inexorably enter in a long battle for survival above sea level reef growth and or uplift may also prolong the island s lifetime above the waves the ultimate fate of most islands however is to be drowned through subsidence and or truncation by marine erosion

depositional environment and climate changes during the late pleistocene as recorded by the netiesos section in southern lithuania the netiesos section in southern lithuania exposes a late pleistocene sedimentary sequence at a depth of between 17 and 4 m an interdisciplinary study of the section investigated the environmental changes that occurred in the study area during the greater part of marine isotope stage mis 5 geochemical thermoluminescence palaeontological plant macro remain diatoms fishbones and magnetic susceptibility analyses were performed on numerous sediment samples chronological control of the sequence was provided by electron spin resonance esr infrared optically stimulated luminescence ir osl and conventional radiocarbon dating methods this interdisciplinary approach enabled the subdivision of the section into stratigraphic units reflecting environmental changes according to chronological data the development of the netiesos palaeolake began at the end of the medininkai saalian glaciation which is thought to correlate with mis 6 and continued up to the thermophilous deciduous forests phase of the subsequent last interglacial of mis 5 sediments of the final phase of the interglacial are missing as are the initial and final phases of the following early nemunas weichselian cooling mis 4 the palaeomagnetic blake event was recorded in the interglacial sediments one of the richest palaeofloras in the east baltic region was observed representing the second half of mis 5 the implications of the results for the regional late pleistocene climato chronostratigraphy are discussed

geostrophic circulation or shallow marine turbidity currents the dilemma of paleoflow patterns in strom influenced prograding shoreline systems in ancient storm influenced prograding shoreline sequences sole marks mainly tool marks from hummocky crossstratified storm deposits are commonly oriented normal to paleoshoreline and the trend of paleobathymetric contours in the basin asymmetrical tool marks typically indicate flows directed offshore several workers have attributed their formation to storm generated shallow marine turbidity currents this interpretation conflicts with observations from modern shelves where storm driven circulation generally is geostrophically balanced and time averaged bottom currents approximately parallel bathymetric contours and the local shoreline the resolution of these apparently conflicting observations may lie in the realization that tool marks and many other small paleoflow indicators form almost instantly as the result of instantaneous flow conditions very near the bed beneath storm generated flows in the shallow ocean instantaneous and time averaged characteristics of the bottom boundary layer generally exhibit little similarity storm generated tool marks are formed by the movement of large tools within the thin less than 1 m inner boundary layer resulting from the superimposition of waves and currents the orientation of the peak instantaneous shear stress moving large tools under such combined flows mainly reflects wave orbital motions which typically are normal to shore the magnitude of stress is greatly increased in the offshore direction and decreased in the onshore direction by superimposition of a steady current with an offshore component of flow but the direction of stress is only slightly affected in ancient storm influenced sequences therefore shore normal tool marks generally were not formed by turbidity currents rather their orientation is best attributed to shoaling waves approaching the coast at a very high angle asymmetrical tool marks are directed offshore due to enhanced shear stress on the offshore stroke of waves superimposed on a geostrophic current with an offshore flow component tool marks do not reflect the time averaged bottom flow direction in fact they provide almost no information concerning steady bottom currents in contrast high angle cross beds formed in coarser sediment by the migration of dunes and sandwaves although relatively rare in offshore storm deposits generally reveal approximately shore parallel flows in ancient systems cross beds closely reflect the time averaged flow direction in the outer boundary layer of a geostrophic current for three reasons 1 the net transport direction for sand moving as bed load beneath a combined flow lies between the directions of peak instantaneous shear stress and time averaged shear stress 2 large ripples disrupt the thin inner boundary layer and 3 long time intervals relative to wave induced velocity oscillations are required to form large ripples

quantitative reconstruction of climate variability during the eemian merkinė and weichselian nemunas in lithuania abstract little is known concerning climate changes in the eastern baltic region during the last interglacial glacial cycle and in particular climate changes during the weichselian in this study a quantitative reconstruction of the mean january and july temperature for the medininkai 117 site in lithuania is presented the reconstruction is based on pollen and plant macrofossils from this site which reveal that the vegetation was characteristic of many northern europe sites during the eemian and early weichselian gradual evolution of the vegetation suggests that relatively uniform climate conditions existed during the eemian our reconstructions support the view of a relatively stable eemian with short cooling phases of low amplitude a strong increase in temperature was apparent during the beginning of the interglacial and decrease during the transition to the weichselian reconstructed july temperatures of the eemian interglacial were approximately 2 c higher than today 18 5 c today 16 2 c and were similar to today for january 5 2 c today 5 1 c july temperatures during the early weichselian were only 2 c lower than during the eemian whereas the january temperatures gradually decreased winter temperatures were relatively high above 10 c during the early weichselian

offshore transport and sand body formation evidence from a steep high energy shoreface southeastern australia abstract elongate shore parallel sand bodies lie on the lower shoreface of the embayed and cliffed coast of central new south wales australia these sand bodies are 10 to 30 m thick extend almost continuously for 40 km parallel to the coast and display a pronounced convexity on the sea floor in profile sediment sampling and detailed seismic reflection and side scan sonar profiling provide evidence that the upper part of these large lobate sand bodies consists chiefly of sand transported downslope from the upper shoreface and surf zone the sand bodies consist entirely of marine sand probably derived locally from retreating embayed beaches and in part from sandstone cliffs channels and sediment lobes oriented normal to the shoreline and internal structure indicate growth by seaward progradation and surface morphology indicates coalescing of lobes and damming of bed load sediment against bed rock ridges in water depths of 70 to 80 m the precise mechanism or mechanisms of seaward transport on the shoreface is unresolved we surmise that during storm events disturbance by large waves and seaward transport by downwelling bottom currents result in sand movement onto and across the sand body surface at depths of 40 to 80 m concurrent modification of the sand bodies by shore parallel processes is suggested by textural trends bed forms and the overall alongshore continuity of the sand bodies