conodont biozonation in the upper arenig of sweden conodont faunas from the arenigian lanna volkhov stage in baltoscandia have been the subject of intensive study particularly during the last decade and different biozonations based on them have been proposed the application of some of these zones is discussed here the present investigation is mainly based on 64 samples from ten sections in sweden but conodont collections from bornholm denmark and tamsalu estonia have also been studied lindstrom s 1971 concept of the upper arenigian microzarkodina parva zone is essentially replaced by a revised baltoniodus norrlandicus zone the zone corresponds closely to bagnoli stouge s 1997 recently distinguished b norrlandicus and lenodus antivariabilis zones which can be recognized in sections where a more detailed subdivision and correlation is possible under the names of the t quadrangulum subzone and the l antivariabilis subzone respectively

definition of the tremadoc series and the series of the ordovician system in britain the tremadoc series and series of the ordovician system are widely used in international correlations and this review explains and summarizes how the base of each of these series is recognized in britain no type section in which the base of any one of them is displayed has ever been selected and formally designated hence the basal horizon of each series is a matter of general understanding rather than precise definition this general understanding is of particular biozones or of assemblages of fossils and their relative ages the geographical separation between type sections of series and differences in facies complicate the understanding of relative ages of biozones brachiopod and trilobite faunas of the llandeilo caradoc and ashgill series have been studied in detail in recent years and biozones proposed these biozones have proved difficult or impossible to recognize outside their type areas in britain and brachiopod trilobite faunas of the tremadoc arenig and llanvirn series are likewise highly provincial thus for correlation within and outside britain attention has been focused on the standard graptolite biozones particularly since such conodont faunas as have been found have not proved useful yet there are problems associated with these standard biozones for example the tetragraptus approximatus biozone is unknown in wales or england the relationship between the base of the glyptograptus teretiusculus biozone and the earliest llandeilo shelly faunas requires clarification and at what level the base of the caradoc series may lie in the nemagraptus gracilis biozone is unknown thus to bring precision to definitions of ordovician series in britain the identification of continuous fossiliferous sequences that will serve as stratotypes is required such a section for the basal portion of the tremadoc series has recently been proposed systematic studies related to particular biozones are needed for example early caradoc and early ashgill brachiopods and graptolites of the didymograptus bifidus and glyptograptus teretiusculus biozones the stratigraphical ranges and abundances of species in particular sections require documentation so that the type of biozone assemblage acme concurrent range etc may be recognized such work could lead towards chronostratigraphy the provision of a standard stratigraphical scale in britain for the tremadoc series and ordovician series

the dependence of sea surface roughness on the height and steepness of the waves it is proposed that the sea surface roughness zo can be predicted from the height and steepness of the waves zo hs a hs lp b where hs and lp are the significant wave height and peak wavelength for the combined sea and swell spectrum best estimates for the coefficients are a 1200 b 4 5 the proposed formula is shown to predict well the magnitude and behavior of the drag coefficient as observed in wave tanks lakes and the open ocean thus reconciling observations that previously had appeared disparate indeed the formula suggests that changes in roughness due to limited duration or fetch are of order 10 or less thus all deep water pure windseas regardless of fetch or duration extract momentum from the air at a rate similar to that predicted for a fully developed sea this is confirmed using published field data for a wide range of conditions over lakes and coastal seas only for field data corresponding to extremely young waves u10 cp 3 were there appreciable differences between the predicted and observed roughness values the latter being larger on average significant changes in roughness may be caused by shoaling or by swell a large increase in roughness is predicted for shoaling waves if the depth is less than about 0 2lp the presence of swell in the open ocean acts on average to significantly decrease the effective wave steepness and hence the mean roughness compared to that for a pure windsea thus the predicted open ocean roughness is at most wind speeds significantly less than is observed for pure wind waves on lakes only at high wind speeds such that the windsea dominates the swell do the mean open ocean values reach those for a fully developed sea

direct measurements of wind stress over the surf zone field data of the wind stress over surf zone waves are presented from an open ocean beach on the east australian coast two ultrasonic anemometers were deployed at nominal heights of 5 and 10 m above the water surface in the intertidal and inner surf zones with concurrent measurements of water levels and offshore wave parameters following a rigorous quality control procedure the wind stress was determined by the eddy correlation technique a constant stress layer was observed between 5 and 10 m elevation considering near neutral conditions only the wind drag coefficients were found to systematically change with the wind angle of approach relative to the shoreline and are much smaller for longshore wind than during onshore wind the concept of an apparent wave steepness changing with wind direction is suggested to explain this behavior the drag coefficients over the surf zone during onshore wind and near neutral conditions were determined to be almost twice the values expected at the same wind speed and open ocean conditions the observed charnock coefficient was similarly an order of magnitude larger than open ocean values a wave celerity of the order of that expected in the inner surf zone is required to explain the observed large roughness and drag coefficients using existing wave age dependent parameterizations this suggests that the slower wave celerity in the surf zone is an important contributor to the increased wind stress in addition to the sawtooth wave shape key points a new field data set of the wind stress over surf zone waves is presented concept of an apparent wave steepness is proposed to explain drag observations surf zone drag coefficients were almost twice the values outside the surf

japan s sediment flux to the pacific ocean revisited abstract quantifying volumes and rates of delivery of terrestrial sediment from island arcs to subduction zones is indispensable for refining estimates of the thickness of trench fills that may eventually control the location and timing of submarine landslides and tsunami generating mega earthquakes despite these motivating insights knowledge about the rates of erosion and sediment export from the japanese islands to their pacific subduction zones remains patchy regardless of the increasing availability of highly resolved data on surface deformation climate geology and topography traditionally natural erosion rates across the island arc have been estimated from regression of topographic catchment metrics and reservoir sedimentation rates that were recorded over several years to decades we review current research in this context correct for a systematic bias in one of the most widely used predictions and present new estimates of decadal to millennial scale erosion rates of japan s terrestrial inner forearc we draw on several independent and unprecedented inventories of mass wasting reservoir sedimentation and concentrations of cosmogenic 10be in river sands we find that natural 10be derived denudation rates of several mm yr 1 in the japanese alps have been sustained over several centuries to millennia and are within error roughly consistent with sediment yields inferred from artificial reservoir sedimentation local exceptions may likely result from release of sediment storage or regional landsliding episodes that trigger transient sediment pulses our synopsis further reveals that catchments draining japan s eastern seaboard differ distinctly in their tectonic lithological topographic and climatic characteristics between the tohoku japanese alps and nankai inner forearc segments which is underscored by a marked asymmetric pattern of erosion rates along the island arc erosion rates are highest up to at least 3 mm yr 1 in the japanese alps that mark the collision of two subduction zones where high topographic relief hillslope and bedrock channel steepness foster rapid denudation by mass wasting comparable if slightly lower erosion rates characterise the nankai inner forearc in southwest japan most likely due to higher typhoon driven rainfall totals and variability rather than its high topographic relief in contrast our estimated erosion and flux rates are lowest in the tohoku inner forearc catchments that feed sediment into the japan trench we conclude that collisional mountain building of the japanese alps drives some of the highest erosion rates in the island arc despite similar uplift and precipitation controls in southwest japan we infer that prior to extensive river damming reservoir construction and coastal works the gross of japan s total sediment export to the pacific ocean entered the accretionary margin of the nankai trough as opposed to the comparatively sediment starved japan trench compared to documented contemporary rates of sediment flux from mountainous catchments elsewhere in the pacific the rivers draining japan s inner forearc take an intermediate position despite high relief steep slopes very high seismicity and frequent rainstorms however the average rates of millennial scale denudation in the japanese alps particularly are amongst the highest reported worldwide local mismatches between these late holocene and modern rates emphasise the anthropogenic fingerprint on sediment retention that may have significantly reduced the island arc s mass flux to its subduction zones as is the case elsewhere in east and southeast asia

high resolution correlation of anglo welsh middle to upper ordovician sequences and its relevance to international chronostratigraphy abstract continuously fossiliferous sections in south wales and shropshire spanning the base of the upper ordovician permit precise correlation of the nemagraptus gracilis biozone a horizon currently under scrutiny for the selection of a global stratotype section and point gssp using graphic correlation we have compiled a new composite global standard for the middle upper ordovician which shows that the first occurrence of the key graptolite n gracilis is not everywhere of the same age appearing earlier in north american successions than it does in britain species of dicellograptus by contrast appear to be almost synchronous in their first appearance the status and correlation of standard british biozones through the llandeilian caradoc interval based on graptolites and trilobites are revised suitable sections for the definition of bases of biozones are proposed if the base of the n gracilis biozone is accepted internationally as the base of the upper ordovician this biozone being coincident with the base of the caradoc series there are sections suitable for its precise definition in the british succession

millennial scale stratigraphy of a tide dominated incised valley during the last 14 kyr spatial and quantitative reconstruction in the tokyo lowland central japan spatial and quantitative analysis of infilling processes of the tide dominated incised valleys beneath the tokyo lowland during the last 14 kyr was undertaken by using data from 18 sediment cores 467 radiocarbon dates and 6100 borehole logs the post last glacial maximum valley fills consist of braided river meandering river estuary spit and delta systems in ascending order the boundary between the estuary and delta systems is regarded as the maximum flooding surface the maximum flooding surface beneath the tokyo lowland is dated at 8 ka in the arakawa valley and 7 ka in the nakagawa valley this age difference is due to the migration of the tone river from the arakawa valley to the nakagawa valley at 5 ka and suggests that the widely held view that the global initiation of deltas coincided with the abrupt rise of sea level at 9 to 8 ka is true only where there has been steady sediment supply from major rivers the meandering river system is dominated by sheet like sands that were deposited during lateral migration of channels during the younger dryas and isolated vertical sands within muds that reflect vertical aggradation of channels before and after the younger dryas the transition between these channel geometries is controlled by a threshold sea level rise of 4 to 7 mm yr 1 before migration of the tone river at 5 ka the tide dominated bay in the nakagawa valley was filled by upward fining laterally accreting muds the muds accreted from the margin to the axis of the bay such lateral accretion of suspended particles derived from outside the bay has been documented in other tide dominated coastal environments and is probably common in other similar settings after the migration of the tone river the bay was filled by upward coarsening deltaic sediments

a revision of ordovician series and stages from the historical type area this paper is a revision of the standard chronostratigraphy of the ordovician of the historical type area in england and wales the revision is a response to the need for more precise definitions of series and stages especially for practical international correlation in some cases this has entailed moving horizons for series bases away from those in the classical sections the scheme will be used as the standard for a forthcoming revision of the correlation chart of the british ordovician system the ordovician is divided into five series tremadoc arenig llanvirn caradoc and ashgill the llanvirn is extended to include part of the classical llandeilo series which is included within it as a stage where stage subdivisions of standard series have not yet been defined as in the tremadoc they are proposed in this paper however bancroft s fine stadial divisions of the caradoc which have been criticized for their brevity and local utility are combined into four new stages which will have wider application the former caradoc subdivisions are retained as substages for the purposes of regional correlation

dynamic particle segregation and accumulation processes in time and space revealed in a modern river dominated delta a spatiotemporal record of the kiso river delta central japan abstract the holocene succession of the kiso river delta a sand rich river dominated delta in central japan was analyzed at high temporal and spatial resolution the results demonstrate how the spatiotemporal distribution of sedimentary facies gross sediment accumulation rates and accumulation rates of mud versus sand relate to the geomorphic development of the delta and the post glacial sea level history the centers of peak mud and sand accumulation have migrated seaward in parallel during a regressive stage from 6 5 ka to the present at the rate of 3 9 m y the mud and sand accumulation centers mark the bottom and top respectively of the delta front slope the sediments of the prograding delta show strong sorting and clear upward coarsening because of the steep slope of the delta front such internal topographic control redistributes and separates the coarse and fine fractions of the fluvial input during regression the topographic controlled sedimentary segregation constructs delta front topography in reverse therefore the proportion of sand to mud in the fluvial input controls the stability of the delta front morphology our modeling of the kiso river delta may have implications for prediction of coastal flooding adjacent to deltas in other parts of the world

wind and waves in extreme hurricanes waves breaking at the ocean surface are important to the dynamical chemical and biological processes at the air sea interface the traditional view is that the white capping and aero dynamical surface roughness increase with wind speed up to a limiting value this view is fundamental to hurricane forecasting and climate research but it has never been verified at extreme winds here we show with observations that at high wind speeds white caps remain constant and at still higher wind speeds are joined and increasingly dominated by streaks of foam and spray at surface wind speeds of 40 m s the streaks merge into a white out the roughness begins to decrease and a high velocity surface jet begins to develop the roughness reduces to virtually zero by 80 m s wind speed rendering the surface aero dynamically extremely smooth in the most intense part of extreme or major hurricanes wind speed 50 m s a preliminary assessment shows that cross swell dominant in large regions of hurricanes allows the roughness under high wind conditions to increase considerably before it reduces to the same low values

the sequence stratigraphy of fluvial depositional systems the role of floodplain sediment storage abstract the currently used model for alluvial sequence stratigraphy has been criticised miall 1991 and an alternative model is offered here in this model alluviation mainly takes place during transgressive and not highstand phases when accommodation space allows sediment storage the high capacity for some river systems to store floodplain sediments is a critical consideration the effects of climatic and intrinsic geomorphic changes during fluvial deposition are likely to greatly complicate simple base level controlled sequence models and recognising higher order fourth and fifth order cycles will be particularly difficult

revisiting the definition of the drag coefficient in the marine atmospheric boundary layer abstract a new functional form of the neutral drag coefficient for moderate to high wind speeds in the marine atmospheric boundary layer for a range of field measurements as reported in the literature is proposed this new form is found to describe a wide variety of measurements recorded in the open ocean coast fetch limited seas and lakes with almost one and the same set of parameters this is the result of a reanalysis of the definition of the drag coefficient in the marine boundary layer which finds that a constant is missing from the traditional definition of the drag coefficient the constant arises because the neutral friction velocity over water surfaces is not directly proportional to the 10 m wind speed a consequence of the transition to rough flow at low wind speeds within the rough flow regime the neutral friction velocity is linearly dependent on the 10 m wind speed consequently within this rough regime the new definition of the drag coefficient is not a function of the wind speed

response of a coarse grained fluvial to coastal depositional system to glacio eustatic sea level fluctuation since the last glacial maximum an example from the tenryu river japan modern coarse grained deltas are common in tectonically active coastal zones however the stratigraphic architecture and evolution of these deltas in relation to allogenic forcing are poorly understood compared with fine grained deltas mainly because of short vertical exposure in outcrop and lack of detailed ages this paper investigates the coarse grained delta in the lower reaches of the tenryu river developed at an island arc collision coast through analyses of radiocarbon dated core sediments and borehole data the vertical successions of the proximal and distal part of the delta constitute basal coarse grained braided river deposits overlain by fine grained sand and mud accumulated under temporary marine influence the fine grained deposits in turn are covered mainly with coarse grained braided river deposits in the proximal part and upper shoreface to beach sand and gravel in the distal part at the apex of the delta in contrast the fine grained deposits are almost absent and thick gravels dominate allogenic forcing especially the rate of glacioeustatic sea level change has influenced the accumulation rates and stacking pattern of the delta most of the sediment may have been transported to the deep sea via a canyon and deposition has been minimal under the present subaerial delta before 14 ka although aggradation almost equivalent to rapid sea level rise 15 mm yr is found at the proximal part between ca 11 5 and 8 ka even with significant basin sediment yield and supply transgression occurred and gravel supply to the coast waned notably only 30 of the sediment yield from the upstream catchment might have been trapped under the present delta plain during that period this means that large amounts of sediment were transported farther offshore or alongshore in contrast slow aggradation in the proximal part and apex of the delta accompanied by progradation in the distal part might become dominant during the past 8 ka when the rate of sea level rise decreased to 10 mm yr a similar response was also observed at other holocene fluvio deltaic systems although they are very different in their geological setting such as sediment supply water discharge tectonic movement and gradient of river and shelf the results imply that the rate of sea level rise and its change have a greater significance on coastal depositional systems than other factors such as fluvial sediment supply this study contributes to an improved understanding of evolution of modern and ancient coarse grained deltas and reconstruction of sea level change from geological data

deglacial meltwater pulse 1b and younger dryas sea levels revisited with boreholes at tahiti reconstructing sea level changes during the last deglaciation provides a way of understanding the ice dynamics that can perturb large continental ice sheets the resolution of the few sea level records covering the critical time interval between 14 000 and 9 000 calendar years before the present is still insufficient to draw conclusions about sea level changes associated with the younger dryas cold event and the meltwater pulse 1b mwp 1b we used the uranium thorium method to date shallow living corals from three new cores drilled onshore in the tahiti barrier reef no significant discontinuity can be detected in the sea level rise during the mwp 1b period the new tahiti sea level record shows that the sea level rise slowed down during the younger dryas before accelerating again during the holocene

air water momentum flux observations over shoaling waves abstract this paper drab with simultaneous momentum flux observations from four towers placed at different depths along a shore normal line at the west end of lake ontario canada the towers were at nominal depths of 12 8 4 and 2 m in order to study the influence of shoaling waves on the air water momentum flux namely the effect of wave steepness and celerity on the aerodynamic roughness of the water surface analysis of the data have shown that the momentum fluxes cannot he explained by mean downwind speed alone u10 in contrast to open ocean experiments in which the wave maturity is generally near full development surface roughness z0 normalized on wave height was parameterized by both the inverse wave age u10 cp and the root mean square wave slope 0 with excellent correlation in each case r2 0 79 multiple regression using both the inverse wave age and the root mean square slope lead to the best results z0 2 26 u10 cp 1 82 3 83 r2 0 90 these findings are presented a

fetch and duration limited nature of surface wave growth inside tropical cyclones with applications to air sea exchange and remote sensing abstractthe 2d wavenumber spectra collected by an airborne scanning radar altimeter in hurricane hunter missions are used to investigate the fetch and duration limited nature of wave growth inside hurricanes despite the much more complex wind forcing conditions the dimensionless growth curves obtained with the wind wave triplets reference wind velocity significant wave height and dominant wave period inside hurricanes except near the eye region are comparable to the reference similarity counterparts constructed with the wind wave triplets collected in field experiments conducted under ideal quasi steady fetch limited conditions in dimensionless terms the youngest waves are in the back quarter of the hurricane in the northern hemisphere the dimensionless frequency decreases systematically counterclockwise ccw and the most mature waves are in the left hand sector except for those waves near the eye region the dominant wave phase speeds are about 0 32 to 0 71 times of the local wind speed

reduction of wind stress due to swell at high wind conditions 1 wind stress over the ocean depends on the sea surface roughness which is determined by the sea state on one hand underdeveloped wind seas rougher than their fully developed counterpart increase the drag on the other hand the presence of swell can modify wind stress by modifying the wind sea roughness this latter mechanism is believed to have a great impact at high winds whenever underdeveloped local waves coexist with swell detailed measurements of wind stress and wavefield in fetch limited growth conditions were made in an area subjected to strong and persistent winds through the analysis of wavefield observations it is found that the presence of swell dampens the short wind waves the observed attenuation is greater for younger wind seas and decreases as the wind waves become older results obtained from modeling the interaction of wind waves and the air flow above point out that the attenuation of short wind waves causes a reduction of the wave supported stress which in turn decreases the total wind stress