self organized criticality in layered lacustrine sediments formed by landsliding landsliding is the dominant mass wasting process in humid temperate uplands and an important regulator of sediment yield from steep land drainage basins information about the magnitude and frequency distribution of landslides has been derived from aerial photography but it has proved difficult to set limits on the long term scaling behavior of landsliding because the requirements of spatial and temporal coherence and the large number of observations necessary to undertake magnitude versus frequency analyses are not easy to fulfill we use a 2250 yr long record of hillslope erosion associated with extreme hydrologic events preserved in sediments from lake tutira new zealand to investigate scaling in landslide deposits both the magnitude versus frequency distribution of sediment layers attributed to landsliding and the distribution of time intervals between landsliding events take the form of power laws the former with an exponent b 2 06 and the latter with an exponent b 1 4 these results suggest that the erosional events originate from a self organized critical process and are in agreement with observations of scaling in turbidite deposits and grain flows in controlled laboratory experiments the implications are that the aggregate behavior of landsliding at the catchment scale is orderly and that the stratigraphic record preserves a unique long term perspective on a fundamental geomorphic process and the extreme hydrologic events that trigger it

landslide occurrence as a response to land use change a review of evidence from new zealand abstract vegetation cover is an important factor influencing the occurrence and movement of rainfall triggered landslides and changes to vegetation cover often result in modified landslide behaviour however it is difficult to relate the occurrence of landslides directly to variations in land use especially in some european countries in contrast new zealand provides a good opportunity to investigate geomorphic responses to anthropogenic land cover changes before european settlers first arrived in the 1840s hilly regions were only marginally influenced by human activity the maoris new zealand s first settlers lived largely on coastal plains or near lakes and rivers they influenced general vegetation cover only through localized burning practices in contrast european settlers moved into the back country and converted extensive hill areas from native forest and bush to pasture this reduced the strength of the regolith and rendered the slopes more susceptible to landslides pulses of natural sedimentation in the pre european period have been related to volcanic activity climatic variability including changes in frequency of cyclonic storms and wind erosion and fluvial erosion following forest fires initiated either by volcanic eruptions or lightning strikes since european deforestation began sediment production has largely been determined by landslide events on unstable slopes thousands of landslides were triggered by high magnitude low frequency climatic events during storms with estimated return periods in excess of 50 years in contrast low magnitude high frequency rainfall events have caused gully and channel erosion examples from different parts of new zealand indicate changes in sediment generating processes following land use modifications after deforestation landslides have contributed significantly to sediment sequences in depositional basins such as lakes swamps estuaries coastal wetlands and the nearshore and offshore zones of continental platforms

a lacustrine record of early holocene watershed events and vegetation history corvara in badia dolomites italy the early middle holocene lacustrine succession of corvara in badia italian dolomites 1521 m a s l records landslides and other watershed events before the onset of human pressure the sensitivity of this archive to relate climate change watershed processes and vegetation dynamics in the catchment has been explored through a stratigraphic study including the analysis of sedimentological features magnetic properties palaeobotanical records and radiocarbon dating a palaeolake existed between 10 1 k and 7 k cal yr bp and was surrounded by a dense conifer forest long term forest dynamics driven by ecological processes and by climatic conditions favourable to upward forest expansion is recorded throughout the pollen record within the fine clastic sedimentation distinct layers enriched in organic debris of terrestrial origin have been attributed to instant events produced by mass movements their age fits the chronology of large landslide events already known in the catchment enabling correlation of the field evidence of landslides with the lacustrine record landslide frequency is controlled by geological and structural factors but it is significantly modulated by the centennial millennial climatic phases that characterise the holocene in the alps the taphonomical properties of pollen and macroremains provided valuable insight on the mechanism of watershed processes copyright 2006 john wiley sons ltd

el nino southern oscillation signal associated with middle holocene climate change in intercorrelated terrestrial and marine sediment cores north island new zealand a synchronous textural variation in intercorrelated high resolution sediment records from floodplain continental shelf and continental slope settings of the eastern north island new zealand provides evidence of increased storminess after ca 4 ka an upcore change in sediment texture reflects the transition to landsliding which supplanted fluvial incision as the dominant mode of sediment production in the middle holocene this signal which appears in all three records indicates a regional response to external forcing and records the impact of an intensified atmospheric circulation marking the establishment of the contemporary climate that is strongly influenced by the el nino southern oscillation the change in climate was a hemispheric event and in the southern hemisphere its timing is confirmed by independent proxy records from elsewhere in new zealand and the circum south pacific region

rock magnetic signature of precipitation and extreme runoff events in south eastern patagonia since 51 200 cal bp from the sediments of laguna potrok aike a 106 m long sediment sequence from the maar lake laguna potrok aike in southern patagonia was recovered in the framework of the international continental scientific drilling program icdp potrok aike maar lake sediment archive drilling project pasado about half of the sedimentary sequence is composed of mass movement deposits mmds and the event corrected record reaches back to 51 200 cal bp here we present a high resolution rock magnetic study revealing two sedimentary facies associated with mmds and characterized by two different types of spurious gyroremanent magnetization grm acquired during static alternating field demagnetization the first rock magnetic signature is detected in mmds composed of reworked sand and tephra material the signature consists of grm acquired during demagnetization of the natural remanent magnetization nrm and other rock magnetic properties typical of iron sulfides such as greigite we interpret these intervals as authigenic formation of iron sulfides in suboxic conditions within the mmd the second rock magnetic signature consists of a series of 10 short intervals located on the top of mmds characterized by grm acquisition during demagnetization of the isothermal remanent magnetization irm based on geological limnological stratigraphic and climatic evidence these layers are interpreted as reflecting pedogenic hematite and or goethite brought to the lake by runoff events related to precipitation and permafrost melt the pedogenic iron minerals mobilized from the catchment most likely settled out of suspension on top of mmds after a rapid remobilization event the series of runoff events corresponds to periods of increased lacustrine productivity in laguna potrok aike and are coeval within the limit of the chronology to warm periods of the last glacial as recorded in antarctica the deglaciation in the mid latitudes of the southern hemisphere and enhanced precipitation during the early holocene in southeastern patagonia

slip slidin away a post glacial environmental history of the waipaoa river basin abstract the dramatic changes that occurred to the post glacial landscape in the headwaters of the waipaoa river basin are a consequence of perturbations about the equilibrium that exists between the rate of tectonic uplift and fluvial incision at times when the amount of coarse sediment delivered to channels exceeds the capacity of streams to remove it the channel bed rises at the rate of tectonic uplift once bedload overcapacity is replaced by undercapacity and the alluvial cover is depleted streams reestablish contact with bedrock and recuperate the time lost to fluvial incision the first major perturbation occurred during the final phase of the last glaciation ca 33 17 5 cal ka when aggradation was driven by a climate forced variation in the relative supplies of sediment and water we suggest that the subsequent transformation of channels in the headwaters of the waipaoa river basin from alluvial to bedrock occurred as the atmospheric and oceanic circulation converged on their contemporary patterns ca 12 cal ka a second major perturbation that continues to the present began ca 1910 1912 ce when a massive increase in sediment load was accompanied by a modest increase in water discharge after the native vegetation cover in the headwaters was replaced by pasture the processes of terrace creation and incision are inherently unsteady and in five interim cases incision was arrested by a transient increase in the thickness of the alluvial cover that was a response to climatic forcing events that disrupted the native vegetation cover in the headwaters also modulated patterns of sediment dispersal and accumulation in other parts of the fluvial system and caused rapid storm driven infilling of the poverty bay flats tectonic subsidence dictates the course of the waipaoa river across poverty bay flats which because the modern rate of floodplain construction by vertical accretion is rapid relative to the amount of destruction by lateral channel migration has remained virtually unchanged for the past 100 years during this time the channel assumed a narrower deeper form that is in equilibrium with the contemporary supply of sediment and hydraulic regime

heightened hurricane surge risk in northwest florida revealed from climatological hydrodynamic modeling and paleorecord reconstruction historical tropical cyclone tc and storm surge records are often too limited to quantify the risk to local populations paleohurricane sediment records uncover long term tc activity but interpreting these records can be difficult and can introduce significant uncertainties here we compare and combine climatological hydrodynamic modeling including a method to account for storm size uncertainty historical observations and paleohurricane records to investigate local surge risk using apalachee bay in northwest florida as an example the modeling reveals relatively high risk with 100 year 500 year and worst case surges estimated to be about 6 3 m 8 3 m and 11 3 m respectively at bald point a paleorecord site and about 7 4 m 9 7 m and 13 3 m respectively at st marks the head of the bay supporting the inference from paleorecords that apalachee bay has frequently suffered severe inundation for thousands of years both the synthetic database and paleorecords contain a much higher frequency of extreme events than the historical record the mean return period of surges greater than 5 m is about 40 years based on synthetic modeling and paleoreconstruction whereas it is about 400 years based on historical storm analysis apalachee bay surge risk is determined by storms of broad characteristics varies spatially over the area and is affected by coastally trapped kelvin waves all of which are important features to consider when accessing the risk and interpreting paleohurricane records in particular neglecting size uncertainty may induce great underestimation in surge risk as the size distribution is positively skewed while the most extreme surges were generated by the uppermost storm intensities medium intensity storms categories 1 3 can produce large to extreme surges due to their larger inner core sizes for apalachee bay the storms that induced localized barrier breaching and limited sediment transport overwash regime surge between 3 and 5 m are most likely to be category 2 or 3 storms and the storms that inundated the entire barrier and deposited significantly more coarse materials inundation regime surge 5 m are most likely to be category 3 or 4 storms

a late holocene marine terrace on the kidnappers coast north island new zealand some implications for shore platform development processes and uplift mechanism abstract a marine terrace up to 6 m above present mean sea level is preserved along 15 km of the kidnappers coast hawke s bay north island new zealand radiocarbon dates for 10 shell samples collected from intertidal marine deposits overlying an uplifted shore platform have a total age range of 590 yr from 2280 50 to 2750 70 yr b p sample age decreases landward suggesting a small relative sea level rise probably as a result of tectonic subsidence prior to uplift rates of contemporary shore platform formation preclude the preservation of a marine terrace subjected to constant aseismic uplift preservation of a subhorizontal uplifted shore platform mantled by intertidal marine deposits with in situ fauna is best explained by abrupt coseismic uplift 2300 yr b p and preceded by tectonic subsidence the presence of a single marine terrace does not permit the calculation of past earthquake magnitude or recurrence but the nne tilt of the 2300 yr old marine terrace indicates continued growth of the north trending late pleistocene kidnappers anticline

low frequency changes in el nino southern oscillation abstract although there are indications from numerical models that el nino southern oscillation enso may be an internal mode of the coupled pacific ocean atmosphere system sensitive to climatic background parameters it has not yet been possible to find significant changes in enso variability between the little ice age and the present yet a number of authors have found qualitative indications in anecdotal and proxy records of shorter century scale variations in the return interval statistics for el nino episodes to objectively determine what nonstationarities exist we statistically examine the el nino occurrences since 1525 compiled by quinn et al we have stratified the return intervals both for strong events and for all events according to two null hypotheses 1 return intervals are stationary over periods of 200 500 years and 2 the intervals are stationary on a centenary time scale between epochs of contrasting solar variability two parameter weibull distributions are fit to subsamples of

the gisp2 δ18o climate record of the past 16 500 years and the role of the sun ocean and volcanoes measured 18o 16o ratios from the greenland ice sheet project 2 gisp2 ice core extending back to 16 500 cal yr b p provide a continuous record of climate change since the last glaciation high resolution annual 18o 16o results were obtained for most of the current millennium a d 818 1985 and record the medieval warm period the little ice age and a distinct 11 yr 18o 16o cycle volcanic aerosols depress central greenland annual temperature 1 5 c maximally and annual 18o 16o for about 4 yr after each major eruptive event on a bidecadal to millennial time scale the contribution of solar variability to holocene greenlandic temperature change is 0 4 c the role of thermohaline circulation change on climate problematic during the holocene is more distinct for the 16 500 10 000 cal yr b p interval analogous to 14c age calibration terminology we express time in calibrated cal yr b p a d 1950 0 cal yr b p the oldest dryas bolling older dryas allerod younger dryas sequence appears in great detail bidecadal variance in 18o 16o but not necessarily in temperature is enhanced during the last phase of lateglacial time and the younger dryas interval suggesting switches of air mass transport between jet stream branches the branched system is nearly instantaneously replaced at the beginning of the bolling and holocene at 14 670 and 11 650 cal yr b p respectively by an atmospheric circulation system in which 18o 16o and annual accumulation initially track each other closely thermodynamic considerations of the accumulation rate temperature relationship can be used to evaluate the 18 o 16o temperature relationship the gisp2 ice layer count years of major gisp2 climate transitions also support the use of coral 14c ages for age calibration

eastern pacific sea surface temperature since 1600 a d the δ18o record of climate variability in galapagos corals we measured stable oxygen isotope ratios and skeletal growth rates in the massive corals pavona clavus and p gigantea from the west coast of isabela island galapagos to assess interannual to decadal climate variability in the eastern pacific comparisons of instrumental data sets show that sea surface temperatures sst in the galapagos region are representative of a broad portion of the eastern equatorial pacific the site is especially well suited for long term studies of the el nino southern oscillation enso phenomenon as it lies within the eastern pacific center of action for thermal anomalies associated with enso the p gigantea isotope record is nearly monthly in resolution spans the period 1961 1982 and shows strong correlation with a galapagos instrumental sst record r 0 90 for annual averages cross spectral analysis shows that sst can explain greater than 80 of the variance in 18o at both the annual cycle and within the high frequency portion of the enso band 3 5 years the p clavus record is annual in resolution extends from 1587 to 1953 a d and was obtained from a 10 m diameter colony preserved within the urvina bay uplift because seawater 18o variations in the region are very small we interpret the urvina bay coral 18o record in terms of annual average sst the isotopic record appears to be a very good but not perfect indicator of enso events and shows good correspondence with the historical enso reconstruction of quinn et al 1987 a number of low 18o excursions that we observe during the 17th and 18th centuries very likely represent enso events that are missing from the historical tabulations most interannual 18o variations between 1607 and 1953 a d represent annual average temperature excursions of 1 to 2 5 c during the little ice age the annual 18o series correlates well with many north american tree ring records and shows low temperatures during the early 1600s and early 1800s and relatively warmer conditions during the 1700s unlike most northern hemisphere tree ring and instrumental records we see no evidence at this site for warming between 1880 and 1940 but rather observe a slight cooling 28 of the total variance the main enso mode is centered at 4 6 years and accounts for 12 of the total variance additional significant oscillations occur at periods of 3 3 6 8 11 17 22 and 34 years both annual growth rate and 18o show variance at periods equivalent to the solar and solar magnetic periods e g 11 and 22 years respectively in addition the amplitude of the 11 year 18o cycle generally varies with the amplitude of the solar cycle supporting previous suggestions that the solar cycle may modulate interannual to decadal climate variability in the tropics the dominant oscillatory modes both within the enso and interdecadal frequency bands shift to shorter periods from the early to middle 1700s and again from the middle to late 1800s this may reflect major reorganizations within the tropical ocean atmosphere system and suggests that tropical pacific climate variability is linked across timescales ranging from years to decades

the little ice age as recorded in the stratigraphy of the tropical quelccaya ice cap the analyses of two ice cores from a southern tropical ice cap provide a record of climatic conditions over 1000 years for a region where other proxy records are nearly absent annual variations in visible dust layers oxygen isotopes microparticle concentrations conductivity and identification of the historical a d 1600 huaynaputina ash permit accurate dating and time scale verification the fact that the little ice age about a d 1500 to 1900 stands out as a significant climatic event in the oxygen isotope and electrical conductivity records confirms the worldwide character of this event

earthquake dammed lakes in new zealand eleven small lakes were formed by landslides caused by the 1929 buller earthquake four others were formed by other historic earthquakes in new zealand at least nine other new zealand lakes are also dammed by landslides and were probably formed by prehistoric earthquakes when recognized by morphology synchronous age and areal distribution earthquake dammed lakes could provide an estimate of paleoseismicity for the past few hundred or thousand years

holocene paleoseismicity in the fold and thrust belt of the hikurangi subduction zone eastern north island new zealand abstract along the 500 km long eastern coastline of the north island new zealand there are at most seven distinct holocene marine terraces aged 7 ka b p or less the highest of the terraces is 27 m above present day mean sea level the coastal region is subdivided into fourteen distinct subregions based on radiocarbon ages of marine deposits overlying wave cut shore platforms and geographic distribution of similarly aged terraces holocene marine terraces are the result of uplift associated with large earthquakes co seismic deformation this conclusion is based on characteristic stepped terrace morphology clustering of ages of terrace deposits within subrogions and the occurrence of co seismic uplift in historic time differential uplift across structures and distinct age variations at subregion boundaries are also characteristic recurrence intervals of uplift in any one terrace sequence vary from 0 4 ka to 2 0 ka and individual amounts of uplift vary from 1 0 m to 4 0 m in the past 2 5 ka ages from all terraces within subrogions indicate at least 21 paleoseismic events affecting coastal areas of eastern north island in that period these events cluster in time and in separate parts of eastern north island several earthquakes occurred 0 3 0 6 1 0 1 5 2 1 and 2 3 ka b p our data strongly support the concept of segmentation of deformation along the subduction margin the likely cause of coastal uplift is movement on steep reverse faults local structures rather than the subduction thrust that propagate from or near the subduction thrust some 20 25 km below the region earthquakes of moment magnitude 7 3 8 0 are estimated to be associated with these fault movements

sediment budget to assess the geomorphic effect of a cyclonic storm new zealand abstract a short term sediment budget was constructed to assess the erosion response of a soft rock hill country watershed to an intense rainstorm event the watershed is located in a landslide prone area on the east coast of the north island new zealand during march 1988 753 mm of rain was recorded over a four day period with 320 mm and 329 mm on successive days known as cyclone bola this was the largest rainstorm event in the tutira watershed in the 93 year rainfall record the budget quantifies the total sediment generated during the storm the relative contribution of erosion processes involved the amount of sediment held in storage and the amount discharged into two lakes within the watershed a landform map of the watershed was constructed and the contribution of each landform type to the total budget was calculated a total of 1 35 0 13 million m3 of sediment was generated during the storm at an average of 420 m3 ha this is equivalent to a denudation value of 42 mm for the total watershed 3208 ha and 83 mm for the landforms severely affected by landsliding 1427 ha of the sediment generated 21 remained on hillslopes 22 was deposited on valley floors 51 was deposited on the lakebeds and the remaining 6 was discharged from the watershed via the lake outlet most of the sediment generated during the storm was from primary source areas on hill slopes with sediment in secondary storage providing only a small contribution landslide erosion was the main process accounting for 89 of the sediment generated channel tunnel gully and sheet erosion were only minor contributors to the budget six hillslope landforms which occupy only 44 of the watershed generated 90 of the sediment the results of this sediment budget when put in context with the storm magnitude frequency history being analysed from lake cores contribute to the identification of sustainable land use and management of soft rock hill country

10 000 yr record of extreme hydrologic events well dated lacustrine sediments provide a hydrologic record indicating that the frequency and magnitude of runoff events and by inference storms have varied over the past 10 k y in northern new england we used five sediment cores and radiocarbon dating to develop a chronology of holocene hydrologic events for the ritterbush pond basin northern vermont chemical and physical analyses allow us to identify 52 distinct layers of predominately inorganic sediment that represent terrestrially derived material delivered to the pond by runoff events the thickness of some layers suggests hydrologic events at least equal in size to and probably much larger than any storm or flood recorded during nearly 300 yr of written regional history layer thickness and frequency and by analogy storm size and recurrence change through the holocene the largest events occurred 2620 6840 and 9440 calibrated 14c years before present cal 14c yr b p the most frequent hydrologic events occurred in three periods 1750 to 2620 6330 to 6840 and 8600 cal yr b p the recurrence interval of layer deposition during stormy periods averages 130 100 cal yr whereas the recurrence interval during less stormy periods is longer 270 170 cal yr the ritterbush pond event record illustrates the potential of inorganic lacustrine sediment to serve as a proxy record for estimating paleoflood frequency and deciphering climate change

climatic fluctuations in northern patagonia during the last 1000 years as inferred from tree ring records abstract millennium old alerce trees fitzroya cupressoides mol johnst have been used to develop a 1120 year reconstruction of the summer temperature departures for the andes of northern patagonia in argentina four main climatic episodes can be distinguished in this proxy paleoclimatic record the first a cold and moist interval from a d 900 to 1070 was followed by a warm dry period from a d 1080 to 1250 correlative with the medieval warm epoch of europe afterward a long cold moist period followed from a d 1270 to 1670 peaking around a d 1340 and 1650 these cold maxima are contemporaneous with two principal little ice age events registered in the northern hemisphere warmer conditions then resumed between a d 1720 and 1790 these episodes are supported by glaciological and palynological data in patagonia following a cold period in the early 1800s tree ring indices have oscillated around the long term mean except for a warmer period from a d 1850 to 1890 correlations between the rio alerce reconstruction and the regional weather stations indicate that the tree ring variations are correlated with a homogeneous summer weather pattern covering patagonia east of the andes from 38 to 50 s

palaeoclimatic implications of a storm erosion record from late holocene lake sediments north island new zealand abstract a ca 2250 year storm history has been identified from a high resolution lake sediment record from the east coast of the north island new zealand this event based chronology identifies 340 storms in the pre european record the record is largely one of natural variability without human impacts layers of minerogenic sediment representing the products of individual storm events are clearly visible in lake cores these storm sediment pulses derived mainly from landslides record the frequency and magnitude of storms clusters of pulses identify six periods of high sedimentation and associated erosion before european settlement a d 1878 at least five of these are interpreted as periods of higher rainfall and probably warmer temperatures since historic records show that most large storms are derived from the subtropics tropics most of the storm periods correspond to warm climate intervals previously identified from new zealand and from southern hemisphere palaeoclimatic evidence the mapara 2 period ca 2090 1855 cal yr b p was the stormiest other periods were of shorter duration the mapara 2 period occurred at times of sustained warmth in the tasmanian and chilean tree ring records which might suggest hemispheric warming at this time one storm period burrell which occurred during the historical enso record was at a time of moderately high enso activity three earlier periods also appear to show responses to enso two storm periods correspond to previously proposed new zealand wide periods of increased erosion and sedimentation estimates of palaeo storm rainfalls from relationships between storm rainfall and sediment thickness of historical events suggest that storm pulses ca 12 mm thick represent palaeo storms of ca 450 mm rainfall

late holocene paleoenvironment in northern new caledonia southwestern pacific from a multiproxy analysis of lake sediments abstract lithostratigraphic and palynological analysis of two cores recovered from the grand lac new caledonia combined with 35 14 c ams dates yields a paleoenvironmental record spanning the last 2000 yr the lithology is represented mainly by clayey or laminated layers a catastrophic event which is marked by very coarse deposits occurred probably between ca 1070 960 cal yr b p and possibly is associated with an unusually severe la nina event before and after this event a similar combination of the two main sediment types is recorded the repeated alternation of laminated and clayey layers is interpreted as the response to local hydrologic forcing which may reflect a shift from relatively wet to relatively drier conditions respectively variable amount of micro charcoal is detected all along the profile without additional evidence notwithstanding the initial local human settlement documented since ca 2900 14 c yr b p micro charcoal occurrence and variability cannot be linked directly to an anthropogenic origin no distinct palynological zonations in relation to the lithology are observed and the vegetation changes may only represent minor transitions across environmental limits

temperature sensitive tree ring width chronologies of pink pine halocarpus biformis from stewart island new zealand abstract long instrumental or proxy climatic records are scarce for the southern hemisphere relative to many northern regions but are essential for a global perspective of past climate variability in this paper we describe two tree ring width chronologies of pink pine which are the first published for stewart island new zealand 47 s 168 e one of the southernmost forested land masses on the globe a chronology for western central stewart island doughboy rakeahua extends from 1682 to 1990 the other for southern stewart island pegasus from 1690 to 1991 both series are positively correlated with warm season surface air temperatures for southern new zealand and vicinity although there are shorter intervals of comparable warmth the highest 20 year periods of growth during the past 300 years occurred during the middle 1950s 1970s coinciding with record warming since around 1950 in new zealand chronologies developed from two related species silver pine lagarostrobus colensoi from ahaura western south island new zealand and huon pine lagarostrobus franklinii from tasmania also indicate recent warming which is unusual although not statistically unprecedented within the contexts of the past 642 and 2290 years of record respectively

holocene aridity and storm phases gulf and atlantic coasts usa abstract a bottomland flora that prevailed between 9900 and 6000 cal yr b p in a north carolina stream valley may not reflect a regionally much wetter atlantic climate coeval with record drought in the great plains region and assumed dry gulf coastal conditions such conditions were inferred for 6000 1000 yr ago when the bermuda high may have consistently occupied summer positions far to the ne arid episodes coeval with the little river local wet interval are known from eolian sediments and pollen spectra in the atlantic and the gulf coastal plain for multiple reasons the regional extent intensity and duration of coastal aridity and alternating wet phases and the bermuda high positions are not yet adequately constrained the climate and edaphic causes for the steadily growing predominance of southern pines over hardwoods achieved between 8900 and 4200 cal yr b p at different sites at different times are similarly still unresolved new data from shelby lake al reconfirms that no credible field or other proxy evidence exists for a previously postulated catastrophic gulf hurricane phase in the late holocene

last glacial aggradation and postglacial sediment production from the non glacial waipaoa and waimata catchments hikurangi margin north island new zealand abstract the sediment flux generated by postglacial channel incision has been calculated for the 2150 km 2 non glacial waipaoa catchment located on the tectonically active hikurangi margin eastern north island new zealand sediment production both at a sub catchment scale and for the waipaoa catchment as a whole was calculated by first using the tensioned spline method within arc map to create an approximation of the aggradational waipaoa 1 surface contemporaneous with the last glacial maximum and second using grid calculator functions in the gis to subtract the modern day surface from the waipaoa 1 surface the waipaoa 1 surface was mapped using stereo aerial photography and global positioning technology fixed the position of individual terrace remnants in the landscape the recent discovery of kawakawa tephra within waipaoa 1 aggradation gravels in this catchment demonstrates that aggradation was coincidental with or began before the deposition of this 22 600 14 c year old tephra and using the stratigraphic relationship of rerewhakaaitu tephra the end of aggradation is dated at ca 15 000 14 c years ca 18 000 cal years bp the construction of the waipaoa 1 terrace is considered to be synchronous and broadly correlated with aggradation elsewhere in the north island and northern south island indicating that aggradation ended at the same time over a wide area subsequent downcutting a manifestation of base level lowering following a switch to postglacial incision at the end of glacial age aggradation points to a significant southern hemisphere climatic warming occurring soon after ca 15 000 14 c years ca 18 000 cal years bp during the older dryas interval elevation differences between the waipaoa 1 c 15 ka terrace and the level of maximum channel incision i e before aggradation since the turn of the 20th century suggest about 50 of the topographic relief within headwater reaches of the waipaoa catchment has been formed in postglacial times the postglacial sediment flux generated by channel incision from waipaoa catchment is of the order of 9 5 km 3 of which 6 6 km 3 is stored within the confines of the poverty bay floodplain thus although the postglacial period represented a time of high terrigenous sediment generation and delivery only 30 of the sediment generated by channel incision from waipaoa catchment probably reached the marine shelf and slope of the hikurangi margin during this time the smaller adjacent waimata catchment probably contributed an additional 2 6 km 3 to the same depocentre to give a total postglacial sediment contribution to the shelf and beyond of 5 5 km 3 sediment generated by postglacial channel incision represents only 25 of the total sediment yield from this landscape with 75 of the estimated volume of the postglacial storage offshore probably derived from hillslope erosion processes following base level fall at times when sediment yield from these catchments exceeded storage

climate of the last 500 years high resolution ice core records precipitation accumulating on the earth s ice sheets and ice caps records a variety of physical and chemical information about the atmosphere and in some cases provides unique insight to both the history and the mechanics of the earth s environmental system high resolution well dated dust records from both polar ice sheets suggest a linkage between increased atmospheric dust and cooler temperatures over antarctica but a similar relationship is not observed in ice cores from either greenland or china net accumulation histories for the last 490 years reveal no discemible global pattern although interesting regional differences and similarities exist excess non sea salt sulfate profiles provide

probability of rupture of multiple fault segments fault segments identified from geologic and historic evidence have sometimes been adopted as features limiting the likely extends of earthquake ruptures there is no doubt that individual segments can sometimes join together to produce larger earthquakes this work is a trial of an objective method to determine the probability of multisegment ruptures the frequency of occurrence of events on all conjectured combinations of adjacent segments in northern california is found by fitting to both geologic slip rates and to an assumed distribution of event sizes for the region as a whole uncertainty in the shape of the distribution near the maximum magnitude has a large effect on the solution frequencies of individual events cannot be determined but it is possible to find a set of frequencies to fit a model closely a robust conclusion for the san francisco bay region is that large multisegment events occur on the san andreas and san gregorio faults but single segment events predominate on the extended hayward and calaveras strands of segments

terrestrial palynology from marine cores as an indicator of environmental change for the waipaoa sedimentary system and north eastern new zealand diverse terrestrial palynomorph assemblages of pleistocene to recent age have been recovered from mainly marine sediment cores along the eastern new zealand margin these assemblages record a range of environmental changes including climate deforestation reforestation rates of erosion sediment provenance and age volcanic activity polynesian and european settlement strength and direction of ocean currents astronomical cyclicity and other major events many of which can be correlated with shorter onshore terrestrial sequences as such pollen yields valuable information on the dynamic new zealand landscape which is of particular relevance to a source to sink approach this paper provides an integrated summary of published and unpublished late pleistocene palynological studies off eastern north island new zealand that gives context for an analysis of cores within and marginal to the waipaoa sedimentary system pollen assemblages faithfully reflect the last glacial vegetation dominated by grass and shrub land species together with elevated tertiary pollen from enhanced erosion of the regolith the glacial termination and holocene were marked by establishment of podocarp forest a mid holocene disappearance of sediment trapping mangroves and introduction of distal pollen with establishment of coastal current systems under rising sea level these natural signals are overprinted by abrupt changes in pollen species caused by volcanic eruptions finally endemic forest and shrub pollen were markedly reduced with human colonisation associated land use changes and introduction of exotic species

speleothem stable isotope records interpreted within a multi proxy framework and implications for new zealand palaeoclimate reconstruction a primary step in the interpretation of speleothem stable isotope records 18o 16o and 13c 12c is to conduct a comparison with other local palaeoclimate proxies here two new master speleothem 18o and 13c records one from eastern north island and the other from western southern south island new zealand are evaluated against independent precipitation and temperature proxy information to assess their palaeoclimate reconstruction potential this comparison also resulted in a serendipitous opportunity to reconstruct past circulation using climate regime classification lorrey a m fowler a m salinger j 2007a regional climate regime classification as a qualitative tool for interpreting multi proxy palaeoclimate data spatial patterns a new zealand case study palaeo 3 in press specifically because these two regional climate districts are hyper sensitive to westerly circulation changes and in many cases exhibit contrasting climate character in response to circulation anomalies for both the western south island and the eastern north island master speleothem 13c records variations tracked changes in relative regional precipitation the 18o master speleothem record for both regions varied with temperature change both records contain strong regional climate signals that suggest they have good value for palaeoclimate reconstruction the ensuing attempt at a multi proxy reconstruction of regional climate regimes from the compiled proxies indicates past circulation in the new zealand sector has varied considerably during the past four millennia centennial scale circulation changes for the past 4000 years are evident and are analogous to modern blocking zonal and trough regime types kidson j w 2000 an analysis of new zealand synoptic types and their use in defining weather regimes international journal of climatology 20 299 316 that characterise changes in present day prevailing westerly circulation this palaeoclimate reconstruction indicates modern regional climate regime classification can be extended at least as far back as the temporal coverage of the records presented here and it can likely be improved on with better dating control and the addition of new records with higher resolution it is also anticipated that future work will expand to include more proxy data from across new zealand to improve the clarity of past climate regime occurrence for the late holocene

a new windstorm proxy from lake sediments a comparison of geological and meteorological data from western germany for the period 1965 2001 1 the feasibility of detecting windstorm layers in lake sediments is explored by comparing quartz grain size data from a freeze core obtained from the schalkenmehrener maar eifel region western germany to recent meteorological wind data the schalkenmehrener maar is appropriate for such a calibration study because the morphological settings of the lake allow the conservation of windstorm layers in particular there is no fluvial sediment inflow and long term wind measurements are available from nearby stations the age model for the uppermost 30 cm of the sediment core is based on measurements of 137cs and 210pb concentrations an ultra high resolution grain size analysis is performed digitally on thin sections and reveals distinct 1 mm thick layers with increased quartz grain content and sharp gaussian grain size distributions which are shifted to larger grain sizes compared to the normal lake sediment in order to compare the occurrence of these layers with meteorological wind data a windstorm index is developed combining data from meteorological stations in the eifel region and reanalyses from the european centre for medium range weather forecast a statistical evaluation of matches between the windstorm index and the core s silt fraction data indicates that the sediment layers very likely coincide with the major windstorm events in the eifel region during the last decades six historical storm are identified this pilot study identifies the main requirements and proposes a novel methodological approach for using sediment data from lakes with similar settings as the schalkenmehrener maar as a new proxy to reconstruct the windstorm record of the geological past

millennial scale storminess variability in the northeastern united states during the holocene epoch for the purpose of detecting the effects of human activities on climate change it is important to document natural change in past climate1 in this context it has proved particularly difficult to study the variability in the occurrence of extreme climate events such as storms with exceptional rainfall1 previous investigations have established storm chronologies using sediment cores from single lakes2 3 4 5 6 7 8 but such studies can be susceptible to local environmental bias here we date terrigenous inwash layers in cores from 13 lakes which show that the frequency of storm related floods in the northeastern united states has varied in regular cycles during the past 13 000 years 13 kyr with a characteristic period of about 3 kyr our data show four peaks in storminess during the past 14 kyr approximately 2 6 5 8 9 1 and 11 9 kyr ago this pattern is consistent with long term changes in the average sign of the arctic oscillation9 suggesting that modulation of this dominant atmospheric mode may account for a significant fraction of holocene climate variability in north america and europe

holocene glacier variations in new zealand a review abstract in the central southern alps of new zealand ice surface lowering has exposed extensive sections of lateral moraines allowing investigation of moraine stratigraphy and genesis the presence of multiple superposed palaeosurfaces within moraine sequences allows recognition of any disturbances displacements or contamination of till layers and interbedded organic material radiocarbon dating of buried wood and soils allows comparison between the holocene glacial history of the eastern ranges and that of the westland region the periodicity of glacier response has been similar to both areas although the precise timing of events has differed due to local climatic and environmental factors in general glaciers in new zealand expanded about 5000 4500 4200 3700 3500 3000 2700 2200 1800 1700 1500 1100 900 700 600 and 400 100 bp

flood stratigraphies in lake sediments a review abstract records of the frequency and magnitude of floods are needed on centennial or millennial timescales to place increases in their occurrence and intensity into a longer term context than is available from gauged river flow and historical records recent research has highlighted the potential for lake sediment sequences to act as a relatively untapped archive of high magnitude floods over these longer timescales abyssal lake sediments can record past floods in the form of coarser grained laminations that reflect the capacity for river flows with greater hydrodynamic energy to transport larger particles into the lake this paper presents a framework for investigating flood stratigraphies in lakes by reviewing the conditioning mechanisms in the lake and catchment outlining the key analytical techniques used to recover flood records and highlighting the importance of appropriate field site and methodology selection the processes of sediment movement from watershed to lake bed are complex meaning relationships between measureable sedimentary characteristics and associated river discharge are not always clear stratigraphical palaeoflood records are all affected to some degree by catchment conditioning fluvial connectivity sequencing of high flows delta dynamics as well as within lake processes including river plume dispersal sediment focussing re suspension and trapping efficiency with regard to analytical techniques the potential for direct e g laser granulometry and indirect e g geochemical elemental ratios measurements of particle size to reflect variations in river discharge is confirmed we recommend care when interpreting fine resolution geochemical data acquired via micro scale x ray fluorescence xrf core scanning due to variable down core water and organic matter content altering x ray attenuation we also recommend accounting for changes in sediment supply through time as new or differing sources of sediment release may affect the hydrodynamic relationship between particle size and or geochemistry with stream power where these processes are considered and suitable dating control is obtained discrete historical floods can be identified and characterised using palaeolimnological evidence we outline a protocol for selecting suitable lakes and coring sites that integrates environmental setting sediment transfer processes and depositional mechanisms to act as a rapid reference for future research into lacustrine palaeoflood records we also present an interpretational protocol illustrating the analytical techniques available to palaeoflood researchers to demonstrate their utility we review five case studies of palaeoflood reconstructions from lakes in geographically varied regions these show how lakes of different sizes and geomorphological contexts can produce comprehensive palaeoflood records these were achieved by consistently applying site validated direct and proxy grain size measurements well established chronologies validation of the proxy process interpretation and calibration of the palaeoflood record against instrumental or historical records