low latitude ionospheric d region dependence on solar zenith angle phase and amplitude measurements of vlf radio signals on a short nearly all sea path between two hawaiian islands are used to find the height and sharpness of the lower edge of the daytime tropical d region as a function of solar zenith angle sza the path used was from u s navy transmitter npm 21 4 khz on oahu to keauhou 306 km away on the west coast of the big island of hawaii where ionospheric sensitivity was high due to the destructive interference between the ionospherically reflected wave and the ground wave particularly around the middle of the day the height and sharpness are thus found to vary from h 69 3 0 3km and 0 49 0 02 km 1 for sza 10 at midday to h 80 km and 0 30 km 1 as the sza approached 70 90 near dawn and dusk for this tropical path additional values for the variations of h and with solar zenith angle are also found from vlf phase and amplitude observations on other similar paths the short path nwc to karratha in nw australia and the long paths nwc to kyoto in japan and nau puerto rico to st john s canada significant differences in the sza variations of h and were found between low and middle latitudes resulting from the latitudinally varying interplay between lyman and galactic cosmic rays in forming the lower d region both latitude ranges showed 0 30 km 1 during sunrise sunset conditions 1

the genesis and recognition of anastomosed fluvial deposits data from the st mary river formation southwestern alberta canada abstract data from modern fluvial systems show that the term anastomosed is best reserved for suspended load systems with multiple channels and very low slope that flow in regions where the hydrograph has a seasonal peak the interchannel areas are topographic lows relative to the channel hanks and are places where crevasse splay marsh and lacustrine sedimentation occurs channel geometry is intrinsically a function of the rate of sediment partitioning the coarsest sediment is deposited in the channels on the levees and in proximal splay complexes whereas the silts and clays are deposited on the rest of the floodplain extrinsic controls on the formation of these systems are geological and climatic they include a source of suspended sediment and a highly seasonal water budget preservat on of anastomosed fluvial deposits requires a mechanism for maintaining very low depositional slopes over geologic time scales data from the st mary river formation in southwestern alberta show that the stratigraphic equivalents of these rivers are ribbon sandstone bodies encased in thin sandstones shales and siltstones the total distribution of facies rather than proof of simultaneous flow in multiple channels can be used to interpret correctly a deposit as anastomosed fluvial although anastomosed fluvial deposits form in a variety of tectonic settings they are apparently most common in foreland basins because these basins provide suitable source rocks and thrusting as a mechanism that can maintain the low depositional slopes over millions of years the mutual interaction among source rock climate and subsidence all of which play critical roles in forming and preserving these distinctive fluvial deposits allows inferences to be drawn regarding paleoclimate and paleoslope that may help constrain models of basin evolution

seasonal and diurnal variation of geomagnetic activity russell mcpherron effect during different imf polarity and or extreme solar wind conditions 1 the russell mcpherron r m effect is one of the most prevailing hypotheses accounting for semiannual variation of geomagnetic activity to validate the r m effect and investigate the difference of geomagnetic activity variation under different interplanetary magnetic field imf polarity and during extreme solar wind conditions interplanetary shock we have analyzed 42 years interplanetary magnetic field and geomagnetic indices data and 1270 ssc storm sudden commencement events from the year 1968 to 2010 by defining the r m effect with positive negative imf polarity imf away toward the sun the results obtained in this study have shown that the response of geomagnetic activity to the r m effect with positive negative imf polarity are rather profound the geomagnetic activity is much more intense around fall equinox when the direction of imf is away the sun while much more intense around spring equinox when the direction of imf is toward the sun the seasonal and diurnal variation of geomagnetic activity after sscs can be attributed to both r m effect and the equinoctial hypothesis the r m effect explains most part of variance of southward imf while the equinoctial hypothesis explains similar variance of ring current injection and geomagnetic indices as the r m effect however the r m effect with positive negative imf polarity explains the difference between sscs with positive negative imfbyaccurately while the equinoctial hypothesis cannot explain such difference at the spring and fall equinoxes thus the r m effect with positive negative imf polarity is more reasonable to explain seasonal and diurnal variation of geomagnetic activity under extreme solar wind conditions

last glacial sea level change deduced from uplifted coral terraces of huon peninsula papua new guinea we have dated corals sampled from the uplifted terraces of huon peninsula papua new guinea that grew during the marine isotope stage 3 to reconstruct sea levels of the last glacial period from 30 to 55 ka kiloannum mass spectrometric u series dating methods resulted in high precision dates and could also be used to recognize diagenetically altered samples the only quantitative test of open systembehaviour of both uraniumand thoriumisotopes involves the com parison of 234 u 238 u ratios at the time of coral growth with present sea water values additional tests included checks for systematic variations in stable isotopes x ray diffraction to detect calcification and petrographic examination sea levels were corrected for glacio hydro isostatic variations and also for the depth range of coral growth habitat sea levels from30 to 55 ka were approxim ately 80 mlower than present superimposed on this general trend four periodic sea level high stands were found at 6 8 ka intervals approximately at 30 38 44 and 52 ka that appear to be synchronous with rapid climate variations previously observed in ice cores and in deep sea sediments r 2001 elsevier science ltd and inqua all rights reserved

extending the radiocarbon calibration beyond 26 000 years before present using fossil corals fossil coral is an excellent archive to extend the radiocarbon 14c calibration beyond tree ring records however published coral data older than 26 000 years before present are too disparate for practical calibration we propose an explanation for these discrepancies trace amounts of secondary calcite and organic matter in fossil corals shift the 14c ages toward younger ages in a series of acid leaching experiments to simulate the standard cleaning procedure prior to 14c analysis we measure up to a 300 enrichment of diagenetic calcite in corals due to the solubility differences between calcite and aragonite in model calculations we show the 14c age offsets produced by acid leaching could be hundreds to thousands of years when typical amounts of calcite are present in samples we demonstrate the necessity and our ability to detect 0 2 calcite in aragonite by x ray diffraction and apply 0 2 calcite as our a priori criterion for our coral samples the estimated age offsets of samples with 0 2 calcite fall within the reported analytical uncertainty of 14c dating in addition we present 14c results from an extended hydrogen peroxide h2o2 pretreatment for coral samples to remove organic matter our data show that treated samples yield consistent or older 14c dates compared to non treated samples these rigorous but necessary screening and cleaning techniques provide precise reproducible and accurate radiocarbon calibration data

global changes in intensity of the earth s magnetic field during the past 800kyr recent advances in palaeomagnetic and dating techniques have led to increasingly precise records of the relative intensity of the earth s past magnetic field at numerous field sites the compilation and analysis of these records can provide important constraints on changes in global magnetic field intensity and therefore on the earth s geodynamo itself a previous compilation for the past 200 kyr integrated 17 marine records into a composite curve1 with the geomagnetic origin of the signal supported by an independent analysis of 10be production made on different cores2 the persistence of long term features in the earth s magnetic intensity or the existence of long term periodic changes cannot however be resolved in this relatively short time span here we present the integration of 33 records of relative palaeointensity3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 into a composite curve spanning the past 800 kyr we find that the intensity of the earth s dipole field has experienced large amplitude variations over this time period with pronounced intensity minima coinciding with known excursions in field direction reflecting the emergence of non dipole components no stable periodicity was found in our composite record and therefore our data set does not support the hypothesis that the earth s orbital parameters have a direct and strong influence on the geodynamo

coupled climate and sea level changes deduced from huon peninsula coral terraces of the last ice age abstract huon peninsula papua new guinea is a tectonically unstable uplifting shoreline ringed by emergent coral terraces the terraces were formed during episodes of rapid sea level rise when corals constructed large discrete coral platforms that were subsequently uplifted uranium series ages of four prominent huon peninsula last glacial ois 3 coral terraces coincide with the timing of major north atlantic climate reversals at intervals of 6000 7000 yr between 30 000 yr and 60 000 yr ago terrace elevations when combined with uplift indicate 10 15 m high sea level excursions at these times we attribute the growth of the terraces directly to sea level rises arising from ice calving episodes from major north atlantic ice sheets and the antarctic ice sheet that precipitated extremes of cold climate called heinrich events these periods are associated with major discharges of land based ice and enhanced concentrations of ice rafted debris in deep sea cores sea levels at this time were 60 90 m lower than present

structure of some lower old red sandstone conglomerates kincardineshire scotland deposition from late orogenic antecedent streams a thick succession of early lower old red sandstone ors conglomerates and subordinate sandstones are preserved in a small fault bounded basin in the ne midland valley of scotland the conglomerates associated with the northern margin of this basin are distinguished by a complex provenance which involved both reworking of existing gravels and addition of contemporary volcanic and plutonic detritus this may explain their characteristic bimodal texture deposition was in large probably permanent low sinuosity channels with evidence for both periods of uniform high stage flow and repeated flow stage fluctuations variable palaeoflows in the basal part of the succession suggest deposition on wet type alluvial fans supplied by feeder channels with a high sediment and water discharge the thickness of the succession the poorly developed cyclothems despite active syndepositional faulting evidence for rapid aggradation and the inferred scale of channel bars and coarsening upward units produced by bar migration suggest the basin may have been externally drained transverse antecedent streams are invoked to account for the structure of alluvium during the early devonian central scotland lay close to the boundary between regions suffering scandian orthogonal shortening and acadian strike slip shear the tectonic controls which governed the preservation of early lower ors sediments may have been largely uncoupled from those determining the supply and dispersal of the sediment

geomagnetic field intensity north atlantic deep water circulation and atmospheric δ14c during the last 50 kyr we present simulated records of past changes in the atmospheric 14c for the last 50 kyr due to changes in geomagnetic field intensity and in the strength of the north atlantic deep water nadw a new geomagnetic record was used largely based on the napis 75 record laj et al phil trans r soc london a 358 2000 1009 1025 which has been extended for the 0 20 kyr interval using archeomagnetic and volcanic data past changes of the nadw were derived from a mineral magnetic study of the cores used in the construction of napis 75 two box models of different complexity 4 and 17 boxes were used to simulate the carbon cycle calculated records of 14c are consistent with experimental determinations for the last 24 kyr for older ages the records calculated with variable oceanic circulation conditions reach values as high as 600 with an average of 500 between 20 and 40 kyr with maxima around 21 30 and 38 kyr gisp2 age model while low values are observed prior to 42 kyr although large inconsistencies in experimental data preclude precise comparison the average record simulated with the 17 box model is overall consistent with the icelandic sea record voelker et al radiocarbon 40 1998 517 534 42 2000 437 452 except for the extremely high peak observed in this record at 40 5 kyr on the other hand the results recently reported from a stalagmite recovered from a submerged cave in the bahamas beck et al science 292 2001 2453 2458 are inconsistent with all our model simulations in the 20 45 kyr interval the improved geomagnetic record combined with the new nadw profile allows us to give a modeled evaluation of the relative contribution of these factors to changes in atmospheric 14c the average simulation provides a first order modeled correction for conventional radiocarbon ages older than 25 kyr for which no calibration curve is available as yet

on the age of the laschamp geomagnetic excursion abstract the laschamp geomagnetic excursion is a critical tie point found directly in deep sea sediment cores and revealed in polar ice as an abrupt change in the rate of cosmogenic nuclide flux despite the importance of this excursion to quantifying paleoclimate proxy records archived in sediment and ice and to providing an independent calibration of the radiocarbon calendar its timing remains poorly known previous k ar 40 ar 39 ar and u th isochron determinations from lava flows at the type locality in the massif central france vary widely are imprecise and suggest a mean age of about 46 2 2 5 ka 2 results of 6 new unspiked k ar and 13 40 ar 39 ar incremental heating experiments on subsamples from three sites on the laschamp and olby flows are concordant and give a weighted mean age of 40 4 1 1 ka 2 uncertainty including analytical sources only that is 10 younger than the previous estimates considering that the 40 k 40 ar decay constant is not known to a precision better than 2 4 the most probable radioisotopic age for the laschamp excursion is 40 4 2 0 ka 2 analytical plus decay constant uncertainties this new age for the laschamp excursion agrees precisely with that deduced from the napis 75 deep sea sediment paleointensity stack when calibrated against the gisp2 ice core chronology using the o isotopes in ice and the magnetic properties of the marine cores

14c activity and global carbon cycle changes over the past 50 000 years a series of 14c measurements in ocean drilling program cores from the tropical cariaco basin which have been correlated to the annual layer counted chronology for the greenland ice sheet project 2 gisp2 ice core provides a high resolution calibration of the radiocarbon time scale back to 50 000 years before the present independent radiometric dating of events correlated to gisp2 suggests that the calibration is accurate reconstructed 14c activities varied substantially during the last glacial period including sharp peaks synchronous with the laschamp and mono lake geomagnetic field intensity minimal and cosmogenic nuclide peaks in ice cores and marine sediments simulations with a geochemical box model suggest that much of the variability can be explained by geomagnetically modulated changes in 14c production rate together with plausible changes in deep ocean ventilation and the global carbon cycle during glaciation

deglacial changes in ocean circulation from an extended radiocarbon calibration temporal variations in the atmospheric concentration of radiocarbon sometimes result in radiocarbon based age estimates of biogenic material that do not agree with true calendar age this problem is particularly severe beyond the limit of the high resolution radiocarbon calibration based on tree ring data which stretches back only to1 2 about 11 8 kyr before present bp near the termination of the younger dryas cold period if a wide range of palaeoclimate records are to be exploited for better understanding the rates and patterns of environmental change during the last deglaciation extending the well calibrated radiocarbon timescale back further in time is crucial several studies attempting such an extension using uranium thorium dated corals3 4 5 and laminae counts in varved sediments6 7 8 9 show conflicting results here we use radiocarbon data from varved sediments in the cariaco basin in the southern caribbean sea to construct an accurate and continuous radiocarbon calibration for the period 9 to 14 5 kyr bp nearly 3 000 years beyond the tree ring based calibration a simple model compared to the calculated atmospheric radiocarbon concentration and palaeoclimate data from the same sediment core suggests that north atlantic deep water formation shut down during the younger dryas period but was gradually replaced by an alternative mode of convection possibly via the formation of north atlantic intermediate water

northern scotland as an atlantic north sea divide president9s anniversary address 1984 from the end of the caledonian orogeny until the present northern scotland has acted as a structural high separating the north sea and atlantic basins or their forerunners the geological history of this positive massif is discussed in relation to that of the adjacent cratonic basins with the objective of determining the extent to which it adapted to regional tectonic developments and the manner in which its responses were modified by the pre existing basement structure from devonian to early palaeocene times the massif was generally low lying and its behaviour with respect to vertical movements was essentially neutral the land surface carved in the crystalline basement during the devonian period was preserved with relatively small modifications and little metamorphic detritus was supplied to the adjacent basins tectonic events of major importance in the basins such as the formation of the north sea and hebridean rift systems produced little change of conditions in the intervening massif it is inferred that the underlying keel of lithospheric mantle was protected from the effects of lithospheric stretching the uneventful history of the massif was interrupted by two phases of mafic igneous activity in late carboniferous and palaeocene times which record responses to regional plate motions the formation of the palaeocene igneous province was followed by a unique phase of uplift as a result of which the ancient sub devonian land surface was elevated and dissected and abundant crystalline detritus was supplied to the north sea the style of these events and the anomalous character of the continental margin off nw britain may have been determined by the refractory nature of the precambrian basement which inhibited stretching prior to sea floor spreading

properties of the quasi 16 day wave derived from eos mls observations 1 this paper describes the use of eos microwave limb sounder mls data to observe the field of traveling planetary waves with quasi 16 day periods this study utilizes mls v2 2 temperature and geopotential data between 1 january 2005 and 31 december 2008 in the range 316 hpa to 0 001 hpa approximately 8 to 97 km to examine these waves analysis demonstrates that the quasi 16 day wavefield is made up of a number of components with westward and eastward propagating s 1 and s 2 waves generally dominant in the northern hemisphere the westward and eastward propagating s 1 waves have similar magnitudes and are larger than the other modes while in the southern hemisphere the eastward propagating s 1 and s 2 waves are larger than the westward propagating wave modes all of the modes examined display strong seasonal patterns in the temperature amplitude significant variability in the wave activity from year to year and the presence of strong pulse like patterns in the activity all of the modes also display large median temperature amplitudes poleward of 40 degrees in both hemispheres our analysis also demonstrates that the variability in winter from year to year is larger in the northern hemisphere than the southern hemisphere detailed study also suggests that the exclusion of waves from regions of negative refractive index squared likely forms much of the seasonal pattern observed thus regions of strong westward wind speeds effectively exclude vertically propagating waves as expected from theory the reflection and absorption of waves associated with critical lines is also likely to explain the frequent occurrence of standing wave patterns in the eos mls temperature observations this study highlights the potential of mls observations for observing waves from the upper troposphere to the lower mesosphere

annual variation in near earth solar wind speed evidence for persistent north south asymmetry related to solar magnetic polarity we study the annual variation in solar wind speed at earth s orbit and in geomagnetic activity since mid 1960 s the two parameters depict a very similar annual variation during the whole period annual variation has maximum amplitude around sunspot minima the phase of annual variation reverses soon after solar maxima following the sun s polarity reversal and indicating a new type of 22 year periodicity stronger solar wind is found at or close to the earth s highest northern southern resp heliographic latitudes during solar minima with a negative positive magnetic polarity this implies an asymmetric sw speed distribution across heliographic equator such that the minimum speed region during solar minimum times is displaced away from heliographic equator towards the northern magnetic hemisphere this may result e g from a systematically larger extension of polar coronal holes from the sun s magnetic south pole toward solar equator we exclude the earlier explanations proposed for annual variation such as accumulation of small comets within 1 au or internal solar variation

variations of younger dryas atmospheric radiocarbon explicable without ocean circulation changes the concentration of radiocarbon 14c in the atmosphere depends on its production rate by cosmic rays and on the intensity of carbon exchange between the atmosphere and other reservoirs for example the deep oceans for the holocene the past 11 500 years it has been shown that fluctuations in atmospheric radiocarbon concentrations have been caused mostly by variations in the solar magnetic field1 2 3 recent progress in extending the radiocarbon record backwards in time4 5 6 7 8 9 10 has indicated especially high atmospheric radiocarbon concentrations in the younger dryas cold period between 12 700 and 11 500 years before the present these high concentrations have been interpreted as a result of a reduced exchange with the deep ocean reservoir caused by a drastic weakening of the deep ocean ventilation7 8 9 11 12 here we present a high resolution reconstruction of atmospheric radiocarbon concentrations derived from annually laminated sediments of two polish lakes lake go ciaz and lake perespilno these records indicate that the maximum in atmospheric radiocarbon concentrations in the early younger dryas was smaller than previously believed and might have been caused by variations in solar activity if so there is no indication that the deep ocean ventilation in the younger dryas was significantly different from today s

annual cycles of u ca in coral skeletons and u ca thermometry abstract we have discovered annual variations in the 238 u 40 ca ratio of porites coral skeletons measurements were made using thermal ionization mass spectrometric techniques yielding precisions of 2 2 for 238 u 40 ca and l 2 for 88 sr 40 ca coralline aragonite subsamples weighed 2 mg enabling submillimeter sampling resolution corresponding to monthly temporal resolution the annual nature of the cycles was confirmed by comparison with annual banding observable in x radiographs for two modern and one fossil sample the amplitude of the u ca variation ranges from 6 to 23 well outside of analytical error as annual u ca cycles appear to be a general feature of primary coralline aragonite the preservation of such features will be important in identifying unaltered coral for u series dating studies u ca variations mimic and are in phase with annual variations in 88 sr 40 ca for a given fractional shift in sr ca the fractional shift in u ca is about 6 times larger for the two modern corals 238 u 40 ca is strongly anticorrelated with measured temperature suggesting that 238 u 40 ca has potential as a paleothermometer if temperature is the only significant control on coralline 238 u 40 ca we reach the following conclusions from analyses of fossil samples a vanuatu sample which grew halfway through the last deglaciation gives u ca temperatures 4 to 5 c below modern values u ca thermometry applied to published data for barbados corals indicates that 1 temperature generally correlates with sea level 2 glacial temperatures stages 2 and 4 were 4 to 6 c lower than interglacial temperatures stages 7a 5e and 1 and 3 temperatures rose from glacial to interglacial values early in the last deglaciation thermometry applied to papua new guinea corals indicates that 1 temperatures were 5 to 6 c lower than interglacial temperatures from 13 to 10 ky bp then rose to present values 9 ky bp 2 the temperature depression between 13 and 10 ky bp is consistent with low temperatures observed in vanuatu during the same time interval and 3 the papua new guinea deglacial temperature history differs from that of barbados the results generally support estimates of tropical temperatures obtained from sr ca thermometry and snow line elevation data but disagree with those based on foram transfer functions a thermodynamic model suggests that coralline 238 u 40 ca may also be sensitive to marine carbonate ion concentration raising the possibility that some of the observed glacial interglacial 238 u 40 ca variation may result from glacial interglacial carbonate ion changes however the key experiments that might establish a coralline 238 u 40 ca carbonate ion relationship have yet to be performed

protactinium 231 dating of carbonates by thermal ionization mass spectrometry implications for quaternary climate change measurement of protactinium 231 231pa in carbonates by thermal ionization mass spectroscopy yields 231pa ages that are more than 10 times more precise than those determined by decay counting carbonates between 10 and 250 000 years old can now be dated with 231pa methods barbados corals that have identical 231pa and thorium 230 230th ages indicate that the timing of sea level change over parts of the last glacial cycle is consistent with the predictions of the astronomical theory two devils hole calcite subsamples record identical 231pa and 230th ages suggesting that the chronology of this climate record is accurate

palynology of the stonehaven group scotland evidence for a mid silurian age and its geological implications palynomorphs from the stonehaven group indicate a late wenlock to early ludlow age this is older than the currently accepted pridoli age based on fish and arthropods reasons for this discrepancy are discussed a previous correlative of the stonehaven group has been the old red sandstone of kerrera argyll however palynological assemblages from both kerrera and the adjacent succession at oban are in fact younger than that from stonehaven in being of latest silurian to earliest devonian age the palynomorphs from kerra and oban lie beneath the important geochronological tie point of the lorne lavas and suggest that the silurian devonian boundary is older than currently accepted

midlatitude ionospheric d region height sharpness and solar zenith angle vlf radio amplitude and phase measurements are used to find the height and sharpness of the d region of the ionosphere at a mid to high geomagnetic dip latitude of 52 5 the two paths used are both from the 23 4 khz transmitter dho in north germany with the first path being northwards and mainly over the sea along the west coast of denmark over a range of 320 425 km and the second also mainly all sea to a single fixed recording receiver at eskdalemuir in scotland 750 km from plots of the measured amplitudes and phases versus distance for the first of these paths compared with calculations using the us navy code modefinder the wait height and sharpness parameters of the d region at midday in summer 2015 are found to be h 72 8 0 2 km and s 0 345 0 015 km 1 at a solar zenith angle 33 from phase and amplitude measurements at other times of day on the second path the daytime changes in h and s as functions of solar zenith angle are determined from shortly after dawn to shortly before dusk comparisons are also made between the modal modefinder calculations and wave hop calculations with both giving similar results the parameters found here should be useful in understanding energy inputs to the d region from the radiation belts solar flares or transient luminous events the midday values may be sufficiently precise to be useful for monitoring climate change

geo archaeological investigations of palaeolithic sites along the ural mountains on the northern presence of humans during the last ice age abstract we review geo archaeological results from six palaeolithic sites along the western flank of the northern ural mountains the oldest traces of human activities dated to around 36 35 14c ka bp 43 40 cal ka were found in alluvial strata at mamontovaya kurya at the polar circle their connection to cultures further south remains uncertain slightly younger artefacts were found at the site zaozer e nearly a thousand km further to the south where a rich archaeological assemblage dated to 34 33 14c ka bp 39 37 cal ka was uncovered from underneath several meters of loess the assemblage contains some small middle palaeolithic like bifaces alongside distinct upper palaeolithic traits such as well defined blades this site also contains some perforated pendants made of freshwater molluscs at the byzovaya site located at 65 n and radiocarbon dated to about 30 29 14c ka bp 34 32 cal ka more than 300 artefacts and several thousand animal remains mostly of mammoth were incorporated in coarse grained debris flow deposits sealed by aeolian sand pending the results from a new technological analysis of the whole artefact assemblage we can yet not decide whether byzovaya should be categorized as a middle or upper palaeolithic site the finds from garchi located in a loess sequence near zaozer e have a similar or slightly younger age than the material from byzovaya also at this site bifacial tools are present alongside some characteristic triangle projectile points as well as some other elements which have nearly identical counterparts in the upper palaeolithic kostenki streletskaya and sungirian complexes unambiguously associated with modern humans we conclude that the initial human colonisations along the ural mountains took place during a relatively favourable period of marine isotope stage 3 when only small mountain glaciers existed in this region the finds from the medvezhia peshera rock shelter have a completely different age 19 16 14c ka bp 23 19 cal ka and character indicating that humans also were present along the urals close to the last glacial maximum 26 19 ka bp the coldest and driest period of the last ice age the few artefacts that were uncovered at pymva shor the northernmost site investigated by us are probably a little younger than those at medveshia peshera but the timing of human presence is not precisely constrained at this site in view of the obtained results it appears that humans were at least temporarily present in these northern landscapes from more than 40 000 years ago and onwards

low mid latitude d region ionospheric perturbations associated with 22 july 2009 total solar eclipse wave like signatures inferred from vlf observations we present first report on the periodic wave like signatures wls in the d region ionosphere during 22 july 2009 total solar eclipse using jji japan very low frequency vlf navigational transmitter signal 22 2 khz observations at stations allahabad varanasi and nainital in indian sector busan in korea and suva in fiji the signal amplitude increased on 22 july by about 6 and 7 db at allahabad and varanasi and decreased by about 2 7 3 5 and 0 5 db at nainital busan and suva respectively as compared to 24 july 2009 normal day the increase decrease in the amplitude can be understood in terms of modal interference at the sites of modes converted at the discontinuity created by the eclipse intercepting the different transmitter receiver great circle paths the wavelet analysis shows the presence of wls of period 16 40 min at stations under total eclipse and of period 30 80 min at stations under partial eclipse 85 54 totality with delay times between 50 and 100 min at different stations the intensity of wls was maximum for paths in the partially eclipsed region and minimum in the fully eclipsed region the features of wls on eclipse day seem almost similar to wls observed in the nighttime of normal days e g 24 july 2009 the wls could be generated by sudden cutoff of the photo ionization creating nighttime like conditions in the d region ionosphere and solar eclipse induced gravity waves coming to ionosphere from below and above the present observations shed additional light on the current understanding of gravity waves induced d region ionospheric perturbations

comment on extending the radiocarbon calibration beyond 26 000 years before present using fossil corals by t c chiu r g fairbanks r a mortlock a l bloom quaternary science reviews 24 2005 1797 1808

calibration of the c 14 timescale over the past 30 000 years using mass spectrometric u th ages from barbados corals uranium thorium ages obtained by mass spectrometry from corals raised off the island of barbados confirm the high precision of this technique over at least the past 30 000 years comparison of the u th ages with 14c ages obtained on the holocene samples shows that the u th ages are accurate because they accord with the dendrochronological calibration before 9 000 yr bp the 14c ages are systematically younger than the u th ages with a maximum difference of 3 500 yr at 20 000 yrbp the u th technique thus provides a way of calibrating the radiocarbon timescale beyond the range of dendrochronological calibration

towards a quantitative method for estimating paleohydrology from clast size and comparison with modern rivers abstract an outcrop based methodology is presented to reconstruct bankfull depth of fluvial channels from clast size based on well established geomorphological procedures results obtained from a lower old red sandstone ludlovian to emsian example from the midland valley basin scotland are calibrated against existing methodologies for reconstruction of bankfull channel depth in fluvial sandstones which utilize preserved channel thickness and preserved dune foreset height the proposed methodology can be applied to pebbly sandstones and conglomerates of fluvial origin it does include significant uncertainties but these are of a range similar to the existing approaches for reconstructing bankfull depth in sandy fluvial systems estimates of bankfull channel depth can be used to reconstruct paleo drainage area using paleo discharge data derived from geomorphological regional curves these regional hydraulic geometry curves are constructed for modern rivers with specific hydro physiographic catchment properties and constrain the relationship between bankfull depth and discharge and bankfull depth and drainage area by comparing the results of outcrop datasets with the regional curves from similar inferred climate regimes an estimate of paleo discharge and paleo drainage area can be derived utilizing these paleohydrological approaches from outcrops of fluvial strata allow quantitative constraints to be placed on paleogeographic reconstructions give a better understanding of paleoclimate and help to constrain provenance studies in addition comparison of the drainage areas and bankfull discharges obtained from this analysis for lower old red sandstone fluvial systems with global data for modern rivers reveals good agreement this indicates that using region specific hydraulic geometry curves to reconstruct ancient fluvial systems can be applied to large rivers interpreted to have a dryland setting possibly sourced from another climatic region as is commonly the case in modern dryland river systems it is recommended that by integrating several techniques more accurate estimates of paleohydrology can be obtained to better reconstruct ancient fluvial environments

extremely large variations of atmospheric 14c concentration during the last glacial period a long record of atmospheric 14c concentration from 45 to 11 thousand years ago ka was obtained from a stalagmite with thermal ionization mass spectrometric 230th and accelerator mass spectrometric 14c measurements this record reveals highly elevated 14c between 45 and 33 ka portions of which may correlate with peaks in cosmogenic 36cl and10be isotopes observed in polar ice cores superimposed on this broad peak of 14c are several rapid excursions the largest of which occurs between 44 3 and 43 3 ka between 26 and 11 ka atmospheric 14c decreased from 700 to 100 per mil modulated by numerous minor excursions carbon cycle models suggest that the major features of this record cannot be produced with solar or terrestrial magnetic field modulation alone but also require substantial fluctuations in the carbon cycle

a large drop in atmospheric 14c 12c and reduced melting in the younger dryas documented with 230th ages of corals paired carbon 14 14 c and thorium 230 230 th ages were determined on fossil corals from the huon peninsula papua new guinea the ages were used to calibrate part of the 14 c time scale and to estimate rates of sea level rise during the last deglaciation an abrupt offset between the 14 c and 230 th ages suggests that the atmospheric 14 c 12 c ratio dropped by 15 percent during the latter part of and after the younger dryas yd this prominent drop coincides with greatly reduced rates of sea level rise reduction of melting because of cooler conditions during the yd may have caused an increase in the rate of ocean ventilation which caused the atmospheric 14 c 12 c ratio to fall the record of sea level rise also shows that globally averaged rates of melting were relatively high at the beginning of the yd thus these measurements satisfy one of the conditions required by the hypothesis that the diversion of meltwater from the mississippi to the st lawrence river triggered the yd event

u sr and mg in holocene and pleistocene corals a palmata and m annularis abstract mg sr and u concentrations are reported for living holocene dead and pleistocene montastrea annularis and acropora palmata in an effort to characterize starting materials and identify diagenetic effects in unrecrystallized skeletal aragonite the data indicate that skeletogenesis of minor elements is a taxa specific process yielding different mg sr and u values for each species during diagenesis sr concentrations increase and mg concentrations decrease in both species u diagenesis appears to be affected by skeletal structure establishment of u concentration ranges for modern corals provides a criterion for selecting samples for dating concentration changes in mg and sr during diagenesis limit their usefulness as paleo environmental indicators

radiocarbon calibration curve spanning 0 to 50 000 years bp based on paired 230 th 234 u 238 u and 14 c dates on pristine corals abstract radiocarbon dating is the most widely used dating technique in the world recent advances in accelerator mass spectrometry ams and sample preparation techniques have reduced the sample size requirements by a factor of 1000 and decreased the measurement time from weeks to minutes today it is estimated that more than 90 percent of all measurements made on accelerator mass spectrometers are for radiocarbon age dates the production of 14 c in the atmosphere varies through time due to changes in the earth s geomagnetic field intensity and in its concentration which is regulated by the carbon cycle as a result of these two variables a radiocarbon age is not equivalent to a calendar age four decades of joint research by the dendrochronology and radiocarbon communities have produced a radiocarbon calibration data set of remarkable precision and accuracy extending from the present to approximately 12 000 calendar years before present this paper presents high precision paired 230 th 234 u 238 u and 14 c age determinations on pristine coral samples that enable us to extend the radiocarbon calibration curve from 12 000 to 50 000 years before present we developed a statistical model to properly estimate sample age conversion from radiocarbon years to calendar years taking full account of combined errors in input ages and calibration uncertainties our radiocarbon calibration program is publicly accessible at http www radiocarbon ldeo columbia edu along with full documentation of the samples data and our statistical calibration model

daytime midlatitude d region parameters at solar minimum from short path vlf phase and amplitude 1 observed phases and amplitudes of vlf radio signals propagating on a short 360 km path are used to find improved parameters for the lowest edge of the d region of the earth s ionosphere at a geomagnetic latitude of 53 5 in midsummer near solar minimum the phases relative to gps 1 s pulses and the amplitudes were measured both near 110 km from the transmitter where the direct ground wave is very dominant and at distances of 360 km near where the ionospherically reflected waves form a modal minimum with the direct ground wave the signals came from the 24 0 khz transmitter naa on the coast of maine near the u s canada border propagating 360 km e ne mainly over the sea to saint john and prince edward island the bottom edge of the midday midsummer ionosphere at 53 5 geomagnetic latitude was thus found to be well modeled by h 71 8 0 6 km and 0 335 0 025 km 1 where h and are wait s traditional height and sharpness parameters used by the u s navy in their earth ionosphere vlf radio waveguide programs the variation of with latitude is also estimated with the aid of interpolation using measured galactic cosmic ray fluxes

relative variations in geomagnetic intensity from sedimentary records the past 200 000 years abstract eighteen records of relative paleointensity from marine sediments have been compiled in order to retrace the global changes in geomagnetic intensity during the past 200 kyr before dealing with any other source of noise we focused on problems inherent to the depth versus time correlations the accuracy and resolution of dating mostly deduced from isotopic stratigraphy were identified as significant factors of distortion we found also that different time scales have been used by authors after readjustment with respect to the same time scale the records were stacked together and the statistical significance of the results tested by a bootstrap technique seventeen records shown to be coherent were combined into a synthetic curve defined as sint 200 other stacks combining various subsets of data were found to be identical to sint 200 except for changes in dispersion in fact the dispersion around sint 200 could be reduced further by improving the correlations without violating the stratigraphy a procedure which at least for some records emphasizes the need for more detailed depth time correlations another characteristic emerging from the results is that paleointensity features as short as 10 kyr are observed between 120 200 ka and can thus in principle be resolved however subsequent refinement is still necessary for this period which is documented by fewer records than the following 120 kyr finally we compared sint 200 with the records from the labrador sea and the lac du bouchet ldb both of which rely mostly on 14c chronology the two records show satisfactory agreement with sint 200 when transferred with respect to the age model established by correlating their 18o labrador and susceptibility features ldb with the 18o reference record the offset of 7 kyr at 40 ka measured in both cases between the 14c and 18o ages is higher than the value deduced from a recent model of a geomagnetic field control of 14c production 1 but is not inconsistent with recent u th dates

rigorous quality control criteria for screening coral samples and radiocarbon calibration data based on 14c 230th 234u 238u and 231pa 235u dated corals a reply to the comment by yusuke yokoyama and tezer m esat on extending the radiocarbon calibration beyond 26 000 years before present using fossil corals by t c chiu r g fairbanks r a mortlock a l bloom quaternary science reviews 24 2005 1797 1808

tectonic significance of the highland boundary fault scotland none of the major roles assigned to the highland boundary fault such as a transcurrent fault with an orogen parallel sinistral displacement of several hundred kilometres or terrane boundary are confirmed the highland boundary fault can be traced ne sw across scotland for 240 km and defines the northern margin of the midland valley except for small outliers of late palaeozoic rocks on the nw side it separates the highland border ophiolite and dalradian rocks of neoproterozoic early ordovician age grampian terrane to the nw from late silurian early carboniferous rocks midland valley terrane to the se the present highland boundary fault is a steep nw dipping post early devonian reverse fault that probably terminates sw of bute stratigraphical and provenance links and palaeostress data limit post early devonian lateral displacement to

comment on radiocarbon calibration curve spanning 0 to 50 000 years bp based on paired th 230 u 234 u 238 and c 14 dates on pristine corals by r g fairbanks et al quaternary science reviews 24 2005 1781 1796 and extending the radiocarbon calibration beyond 26 000 years before present using fossil corals by t c chin et al quaternary science reviews 24 2005 1797 1808

synchronous radiocarbon and climate shifts during the last deglaciation radiocarbon data from the cariaco basin provide calibration of the carbon 14 time scale across the period of deglaciation 15 000 to 10 000 years ago with resolution available previously only from holocene tree rings reconstructed changes in atmospheric carbon 14 are larger than previously thought with the largest change occurring simultaneously with the sudden climatic cooling of the younger dryas event carbon 14 and published beryllium 10 data together suggest that concurrent climate and carbon 14 changes were predominantly the result of abrupt shifts in deep ocean ventilation

perturbations to the lower ionosphere by tropical cyclone evan in the south pacific region very low frequency vlf electromagnetic signals from navigational transmitters propagate worldwide in the earth ionosphere waveguide formed by the earth and the electrically conducting lower ionosphere changes in the signal properties are signatures of variations in the conductivity of the reflecting boundary of the lower ionosphere which is located in the mesosphere and lower thermosphere and their analysis is therefore a way to study processes in these remote regions here we present a study on amplitude perturbations of local origin on the vlf transmitter signals npm nlk naa and jji observed during tropical cyclone tc evan 9 16 december 2012 when tc was in the proximity of the transmitter receiver links we observed a maximum amplitude perturbation of 5 7db on jji transmitter during 16 december event from long wave propagation capability model applied to three selected events we estimate a maximum decrease in the nighttime d region reference height h by 5 2 km 13 december npm and maximum increase in the daytime d region h by 6 1 km and 7 5 km 14 16 december jji the results suggest that the tc caused the neutral densities of the mesosphere and lower thermosphere to lift and sink bringing the lower ionosphere with it an effect that may be mediated by gravity waves generated by the tc the perturbations were observed before the storm was classified as a tc at a time when it was a tropical depression suggesting the broader conclusion that severe convective storms in general perturb the mesosphere and the stratosphere through which the perturbations propagate

sedimentological constraints on the late silurian history of the highland boundary fault scotland implications for midland valley basin development the relationship between movement on the highland boundary fault and deposition of the lower old red sandstone in the midland valley basin of scotland is controversial most models favour mid silurian to early devonian sinistral movement on the highland boundary fault and development of a transtensional midland valley basin to constrain highland boundary fault movement during the late silurian we examine the basal lower old red sandstone alluvial succession exposed adjacent to the highland boundary fault a lack of synsedimentary fault movement indicators coupled with an increase in stratal thickness across the fault indicates that the highland boundary fault was not active during lower old red sandstone sedimentation a transtensional basin model cannot be sustained

corals paleotemperature records and the aragonite calcite transformation oxygen isotopic records from corals play an increasing role in paleoclimatic research and climatic modeling proxy records of sea surface temperature are produced by isotopically analyzing samples drilled from aragonitic caco 3 coral skeletons however drilling aragonite causes a polymorphic inversion to calcite accompanied by 18 o enrichment the isotopic enrichment may occur through atmospheric exchange co 2 degassing or fractionation during digestion regardless of the mechanism dry drilling produced isotopic shifts as large as 0 8 corresponding to an erroneous temperature decrease of 3 c this error is larger than the global temperature rise since the industrial revolution and a substantial part of the global temperature variation over the past 10 ka because the isotopic shift is inconsistent and can occur without the production of measurable calcite detecting and correcting the isotopic shift may be difficult

fingerprints and age models for widespread new zealand tephra marker beds erupted since 30 000 years ago a framework for nz intimate abstract the role of tephras in the nz intimate project is a critical one because most high resolution palaeoclimatic records are linked and dated by one or more tephra layers in this review first we document eruptive distributional and compositional fingerprinting data both mineralogical and geochemical for 22 key marker tephras erupted since 30 000 years ago to facilitate their identification and correlation we include new glass compositional data the selected marker tephras comprise 10 from taupo and nine from okataina volcanoes rhyolitic one from tuhua volcano peralkaline rhyolitic and one each from tongariro and egmont volcanoes andesitic second we use four approaches to develop 2 age models for the tephras youngest to oldest 1 calendar ages for kaharoa and taupo y were obtained by wiggle matching log derived tree ring sequences dated by 14c 2 whakaipo v was dated using an age depth model from peat 3 14 tephras in the montane kaipo peat sequence waimihia s unit k whakatane tuhua mamaku rotoma opepe e poronui c karapiti b okupata konini waiohau rotorua rerewhakaaitu were dated by simultaneously wiggle matching stratigraphic position and 51 independent 14c age points against intcal04 using bayesian probability methods via both oxcal and bpeat and 4 the five oldest tephras erupted before ca 18 000 cal yr bp were dated by calibrating limited numbers of 14c ages using intcal04 okareka or comparison curves of the expanded cariaco basin sequence te rere kawakawa oruanui poihipi okaia kawakawa oruanui tephra the most widely distributed marker tephra was erupted probably ca 27 097 957 cal yr bp potential dating approaches for the older tephras include their identification in antarctic ice cores if present or annually laminated sediments for which robust calendar age models have been constructed high precision ams 14c dating on appropriate material from environmentally stable sites systematic luminescence dating or new radiometric techniques e g u th he if suitable minerals are available and errors markedly reduced further application of bayesian age modelling to stratigraphic sequences of 14c ages possibly augmented with luminescence ages may help refine age models for pre holocene tephras with the largest errors finally we discuss the critical role these marker tephras play in the ongoing construction of an event stratigraphy for the new zealand region which is a key objective of australasian and southern hemisphere intimate projects