Gibraltar woman and Neanderthal Man     

Senior Lecturer  EDWARD P.F. ROSE & Merit Researcher  CHRISTOPHER B. STRINGER 《Geology Today》1997,13(5):179-184

Forbes' Quarry, on the Rock of Gibraltar, yielded a human skull in 1848, one of the earliest Neanderthal skeletal remains known to science. Fragments of a second Gibraltar skull, that of a child, were described from Devil's Tower rock shelter in 1928 and have recently been reconstructed and reinterpreted to emphasize the distinction of Homo neanderthalensis from H. sapiens . Neanderthal skeletal remains are confined to Europe, the Middle East and central Asia, their most recent occurrence arguably a refugium in southern Iberia. The race seemingly became extinct about 30 000 years Before Present, for reasons as yet unknown, but a programme of excavations in Gorham's and Vanguard caves on Gibraltar is in progress to elucidate palaeoenvironmental and behavioural changes as some of the last Neanderthals were succeeded stratigraphically by anatomically modern humans with an Upper Palaeolithic culture.  相似文献   

Loess     

IAN SMALLEY  EDWARD DERBYSHIRE 《Geology Today》1989,5(3):97-99

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Microstructures of sediment flow deposits and subglacial sediments: a comparison     

MATTHEW S. LACHNIET  GRAHAME J. LARSON  DANIEL E. LAWSON  EDWARD B. EVENSON  RICHARD B. ALLEY 《Boreas: An International Journal of Quaternary Research》2001,30(3):254-264

Microstructural analysis of glacial deposits has recently been used as a research tool to determine sediment genesis. However, the occurrence of microstructures in deposits of known origin has not been sufficiently documented, hindering our ability to confidently interpret microstructures in sediments of unknown origin. Our objective is to present a calibration study of microstructures of recent sediment flow deposits and associated sediments from the Matanuska Glacier, Alaska, and to evaluate the degree of commonality with microstructures found in subglacially deformed sediments. Microstructures in sediment flow deposits can be formed as a result of sediment transport, deposition, and/or post-depositional processes, and are related to the viscosity regime of the source flow. Characteristic microstructures formed during brittle deformation include shears, faults, and brecciation; microstructures formed during ductile deformation include folds, pressure shadows, re-orientation of clasts around a 'core' stone, fine laminations, basal shear zones, imbrication, and flow fabrics. Other microstructures include fluid escape and injection structures, clast haloes, and fissility. The results of our comparison suggest that sediment flow deposits share many microstructures in common with subglacially deformed sediments.  相似文献   

Oxygen Isotope Geochemistry of Oceanic-Arc Lavas   总被引：19，自引：11，他引：8  

EILER  JOHN M.; CRAWFORD  ANTHONY; ELLIOTT  TIM; FARLEY  KENNETH A.; VALLEY  JOHN W.; STOLPER  EDWARD M. 《Journal of Petrology》2000,41(2):229-256

Variations of oxygen isotope ratios in arc-related lavas canconstrain the contributions of subducted crustal igneous rocks,sediments, and fluids to the sub-arc mantle. We have measuredoxygen isotope ratios in 72 arc and back-arc lavas from fiveocean–ocean subduction zone systems using laser-fluorinationanalyses of olivine and other phenocrysts and glass. Eightypercent of our samples have  相似文献   

The Chalk sea-urchin Micraster: microevolution, adaptation and predation     

EDWARD P. F. ROSE  NIGEL E. CROSS 《Geology Today》1993,9(5):179-186

Serial variation between Micraster populations from successive zones in the Upper Cretaceous Chalk of Europe is widely cited as evidence for evolution at the species level, whether changes between species are interpreted as gradual or punctuational. That these changes were adaptive and represent an improved functional efficiency with time is also now widely agreed, if not whether the changes were independent of environmental change or a response to it. Dead specimens of Micraster were commonly encrusted by a wide variety of small invertebrates, presumably because they provided islands of hard substrate on an otherwise soft, muddy sea floor. Less commonly, there is evidence that living specimens of Micraster were susceptible to predation by gastropods and other organisms, one of the natural selection pressures favouring adaptation to a burrowing mode of life.  相似文献   

Jesenice—A new meteorite fall from Slovenia     

Addi BISCHOFF  Miha JERSEK  Thomas GRAU  Breda MIRTIC  Ulrich OTT  Jan KUČERA  Marian HORSTMANN  Matthias LAUBENSTEIN  Siegfried HERRMANN  Zdeněk ŘANDA  Marc WEBER  Gerd HEUSSER 《Meteoritics & planetary science》2011,46(6):793-804

Abstract– On April 9, 2009, at 3:00 CEST, a very bright fireball appeared over Carinthia and the Karavanke Mountains. The meteoroid entered the atmosphere at a very steep angle and disintegrated into a large number of objects. Two main objects were seen as separate fireballs up to an altitude of approximately 5 km, and witnesses reported loud explosions. Three stones were found with a total weight of approximately 3.611 kg. The measured activity of short‐lived cosmogenic radionuclides clearly indicates that two specimens result from a very recent meteorite fall. All cosmogenic radionuclide concentrations suggest a rather small preatmospheric radius of <20 cm; a nominal cosmic‐ray exposure age based on ²¹Ne is approximately 4 Ma, but the noble gas and radionuclide results in combination indicate a complex irradiation. Jesenice is a highly recrystallized rock with only a few relic chondrules visible in hand specimen and thin section. The texture, the large grain size of plagioclase, and the homogeneous compositions of olivines and pyroxenes clearly indicate that Jesenice is a L6 chondrite. The bulk composition of Jesenice is very close to the published average element concentration for L ordinary chondrites. The chondrite is weakly shocked (S3) as indicated by the undulatory extinction in olivine and plagioclase and the presence of planar fractures in olivine. Being weakly shocked and with gas retention ages of >1.7 Ga (⁴He) and approximately 4.3 Ga (⁴⁰Ar), Jesenice seems not to have been strongly affected by the catastrophic disruption of the L‐chondrite parent body approximately 500 Ma ago.  相似文献   

Noble gases in presolar diamonds III: Implications of ion implantation experiments with synthetic nanodiamonds     

Gary R. HUSS  Ulrich OTT  Alexey P. KOSCHEEV 《Meteoritics & planetary science》2008,43(11):1811-1826

Abstract— A series of experiments carried out by Koscheev et al. (1998, 2001, 2004, 2005) showed that the bimodal release of heavy noble gases from meteoritic nanodiamonds can be reproduced by a single implanted component. This paper investigates the implications of this result for interpreting the noble gas compositions of meteoritic nanodiamonds and for their origin and history. If the bimodal release exhibited by meteorite diamonds reflects release of the P3 noble gas component, then the composition inferred for the pure Xe‐HL end member changes slightly, the excesses of heavy krypton isotopes that define Kr‐H become less extreme, evidence appears for a Kr‐L component, and the nucleosynthetic contribution to argon becomes much smaller. After correction for cosmogenic neon inherited from the host meteorites, the neon in presolar diamonds shows evidence for pre‐irradiation, perhaps in interstellar space, and a nucleosynthetic component perhaps consistent with a supernova source. After a similar correction, helium also shows evidence for presolar irradiation and/or a nucleosynthetic component. For the case of presolar irradiation, due to the small size of the diamonds, a large entity must have been irradiated and recoiling product nuclei collected by the nanodiamonds. The high ³He/²¹Ne ratio (?43) calls for a target with a (C + O)/heavier‐element ratio higher than in chondritic abundances. Bulk gas + dust (cosmic abundances) meet this criteria, as would solids enriched in carbonaceous material. The long recoil range of cosmogenic ³He argues against a specific phase. The excess ³He in presolar diamonds may represent trapped cosmic rays rather than cosmogenic ³He produced in the vicinity of the diamond crystals.  相似文献   

METEOROLOGICAL TSUNAMIS IN SOUTHERN BRITAIN: AN HISTORICAL REVIEW*     

SIMON K. HASLETT  EDWARD A. BRYANT 《Geographical review》2009,99(2):146-163

ABSTRACT. Meteorological tsunamis, or meteo‐tsunamis, are long‐period waves that possess tsunami characteristics but are meteorological in origin, although they are not storm surges. In this article we investigate the coast of southern Britain‐the English Channel, the Bristol Channel, and the Severn Estuary‐for the occurrence of tsunami‐like waves that, in the absence of associated seismic activity, we recognize as meteo‐tsunamis. The passage of squall lines over the sea apparently generated three of these events, and two seem to have been far‐traveled, long‐period waves from mid‐North Atlantic atmospheric low‐pressure systems. The remaining three wave events appear to have been associated with storms that, among possible explanations, may have induced large‐amplitude standing waves‐such as seiches‐or created long‐period waves through the opposition of onshore gale‐force winds and swells with high ebb tidal current velocities. This coastal hazard has resulted in damage and loss of life and should be considered in future coastal defense strategies and in beachuser risk assessments.  相似文献   

Observation bias correction with an ensemble Kalman filter   总被引：1，自引：0，他引：1  

ELANA J. FERTIG  SEUNG-JONG BAEK  BRIAN R. HUNT  EDWARD OTT  ISTVAN SZUNYOGH  JOSÉ A. ARAVÉQUIA  EUGENIA KALNAY  HONG LI  JUNJIE LIU 《地球，A辑:动力气象学与海洋学》2009,61(2):210-226

This paper considers the use of an ensemble Kalman filter to correct satellite radiance observations for state dependent biases. Our approach is to use state-space augmentation to estimate satellite biases as part of the ensemble data assimilation procedure. We illustrate our approach by applying it to a particular ensemble scheme—the local ensemble transform Kalman filter (LETKF)—to assimilate simulated biased atmospheric infrared sounder brightness temperature observations from 15 channels on the simplified parameterizations, primitive-equation dynamics (SPEEDY) model. The scheme we present successfully reduces both the observation bias and analysis error in perfect-model simulations.  相似文献   

Shock experiments in support of the Lithopanspermia theory: The influence of host rock composition,temperature, and shock pressure on the survival rate of endolithic and epilithic microorganisms     

Cornelia MEYER  Jörg FRITZ  Martin MISGAISKI  Dieter STÖFFLER  Natalia A. ARTEMIEVA  Ulrich HORNEMANN  Ralf MOELLER  Jean‐Pierre De VERA  Charles COCKELL  Gerda HORNECK  Sieglinde OTT  Elke RABBOW 《Meteoritics & planetary science》2011,46(5):701-718

Abstract– Shock recovery experiments were performed with an explosive set‐up in which three types of microorganisms embedded in various types of host rocks were exposed to strong shock waves with pressure pulse lengths of lower than 0.5 μs: spores of the bacterium Bacillus subtilis, Xanthoria elegans lichens, and cells of the cyanobacterium Chroococcidiopsis sp. 029. In these experiments, three fundamental parameters were systematically varied (1) shock pressures ranging from 5 to 50 GPa, (2) preshock ambient temperature of 293, 233 and 193 K, and (3) the type of host rock, including nonporous igneous rocks (gabbro and dunite as analogs for the Martian shergottites and chassignites, respectively), porous sandstone, rock salt (halite), and a clay‐rich mineral mixture as porous analogs for dry and water‐saturated Martian regolith. The results show that the three parameters have a strong influence on the survival rates of the microorganisms. The most favorable conditions for the impact ejection from Mars for microorganisms would be (1) low porosity host rocks, (2) pressures <10–20 GPa, and (3) low ambient temperature of target rocks during impact. All tested microorganisms were capable of surviving to a certain extent impact ejection in different geological materials under distinct conditions.  相似文献