Late-Pleistocene and Holocene remains of Hysterocarpus traski (Tule Perch) from Clear Lake,California, and inferred Holocene temperature fluctuations     

Richard W. Casteel  David P. Adam  John D. Sims 《Quaternary Research》1977,7(1):133-143

The remains of scales of Hysterocarpus traski Gibbons (Tule perch) were found throughout a 27.44-m core from Clear Lake. Most scales occurred between the mud surface and deposits approximately 11,000 years old. Changes in growth rates of the animals were examined by measuring scale annuli and applying an empirically established regression of fish length on scale radius. The data indicate a pattern of accelerating growth rates, reaching a peak between ?4000 and 2800 BP. After ?2800 BP, growth rates decline markedly. Because the growth rates of these animals are essentially dependent on temperature, the changes observed in the patterns of growth probably reflect changes in climate in the northern Coast Range. The general pattern of inferred temperature increase during the early and middle Holocene, ending between ?4000 and 2800 BP, is consistent with evidence from tree-line studies and palynology indicating higher temperatures in parts of the western United States during this period.  相似文献   

Reviews     

A. T. Miesch  A. C. Cook  John W. Harbaugh  H. Colin  P. H. A. Sneath  Douglas M. Hawkins  Martin A. Buzas  D. F. Merriam 《Mathematical Geosciences》1974,6(2):207-217

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Managing and Transforming Water Conflicts edited by Jerome Delli Priscolli & Aaron T. Wolf     

John C. Rodda 《水文科学杂志》2013,58(7):1247-1248

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Siltation analysis in the Neyyar reservoir and forest degradation in its catchment: a study from Kerala state, India     

D. S. Suresh Babu  V. Nandakumar  B. John  B. K. Jayaprasad  S. V. Pramod 《Environmental Geology》2000,39(3-4):390-397

 Impact of catchment erosion and the resultant reservoir siltation from a tropical environment is reported here to discuss the effect of a reservoir in the natural degradation of an evergreen-forested segment. While an area of 8.01 km² has been affected by direct inundation at the full reservoir level, another 2.6 km² area once under thick forest cover, had also lost its identity over the last 38 years by indirect degradation. This zone mainly falls in the confluence of tributaries, namely Neyyar and Mullayar, with the reservoir. The capacity of the reservoir was found to be reduced by 28.8 Mm³ during this period and the annual average loss is calculated as 0.75 Mm³ (0.71%), indicating the intensity of erosion from the catchment zone. In case the proposed upper dam in the reservoir comes into existence, an additional area of 2.4 km² from the virgin forest would be submerged and more area would face degradation around the inundated zone. Received: 29 July 1998 · Accepted: 16 November 1998  相似文献   

A new palaeoenvironmental model for the evolution of the Byzovaya Palaeolithic site,northern Russia     

Herbjørn Presthus Heggen  John Inge Svendsen  Jan Mangerud  Øystein S. Lohne 《Boreas: An International Journal of Quaternary Research》2012,41(4):527-545

Recently, the sediment stratigraphy and geochronology of the well‐known Palaeolithic site Byzovaya in northern Russia were investigated. New technological analyses of the artefacts suggest a Middle Palaeolithic Mousterian culture, and occupation by Neanderthals, not Modern humans as previously thought. We present here a new and detailed documentation of the stratigraphy, including the geological context of the artefacts and faunal remains. From sedimentological criteria we confidently interpret the find‐bearing strata as debris‐flow deposits, covered by aeolian sediments. The chronology is based on radiocarbon and luminescence (OSL) dates from the find‐bearing and overlying strata. The results are utilized to reconstruct the geological history at the excavation area. The stratigraphy varies considerably across the excavation area. The most intact and undisturbed part of the sequence was found inside the most recent Excavation II. In this part the artefacts and bones appear to have been permanently sealed and protected by aeolian sand. The older Excavation I shows a more complicated stratigraphy, as the finds may have been temporarily exposed during the early Holocene owing to ravine incision and slumping activity. The individual radiocarbon dates that were collected from different parts of the site and from various stratigraphic positions are re‐investigated in this study. By using Bayesian statistics the conclusion is that the site was occupied during a restricted period around 30.6–34.7 ka. A series of partly unpublished OSL dates of coversand from different sites demonstrates a regional aeolian signal during the Lateglacial in northern Russia, 15–14 ka.  相似文献   

Crackington beach at first hand     

John Putley 《Geology Today》2000,16(2):62-62

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General relativistic MHD simulations of black hole accretion disks and jets     

John F. Hawley  Kris Beckwith  Julian H. Krolik 《Astrophysics and Space Science》2007,311(1-3):117-125

Accretion disks orbiting black holes power high-energy systems such as X-ray binaries and Active Galactic Nuclei. Observations are providing increasingly detailed quantitative information about such systems. This data has been interpreted using standard toy-models that rely on simplifying assumptions such as regular flow geometry and a parameterized stress. Global numerical simulations offer a way to investigate the basic physical dynamics of accretion flows without these assumptions and, in principle, lead to a genuinely predictive theory. In recent years we have developed a fully three-dimensional general relativistic magnetohydrodynamic simulation code that evolves time-dependent inflows into Kerr black holes. Although the resulting global simulations of black hole accretion are still somewhat simplified, they have brought to light a number of interesting results. These include the formation of electro-magnetically dominated jets powered by the black hole’s rotation, and the presence of strong stresses in the plunging region of the accretion flow. The observational consequences of these features are gradually being examined. Increasing computer power and increasingly sophisticated algorithms promise a bright future for the computational approach to black hole accretion.  相似文献   

Intracrystalline lipids within sulfates from the Haughton Impact Structure—Implications for survival of lipids on Mars     

Stephen A. Bowden  John Parnell 《Icarus》2007,187(2):422-429

Lipids can be present within gypsum as intracrystalline inclusions if they become incorporated within the mineral as is it precipitates. The lipids that comprise these inclusions are protected against alteration or destruction by an external oxidising chemical environment because a protective mineral matrix surrounds them. Sulfate minerals are abundant on the surface of Mars and were present in the samples that were analysed by the Viking landers. The quantities of secondary intracrystalline fossil-lipids that are present in samples of gypsum and gypsum-rich soils from the Haughton Impact Structure, Devon Island, Canadian High Arctic are sufficient to suggest that if a similar concentration of fossil lipids was present in the sulfate-rich samples analysed by the Viking Landers then they could have been detected. Possible reasons why a secondary fossil-lipid signature was not detected include a poor rate of conversion during pyrolysis, exposure of intracrystalline lipids during periods of weathering to oxidative martian diagenesis, a low level of biological productivity or an absence of a source for lipids on the surface of Mars. Polycyclic aromatic hydrocarbons of meteoritic origin, and terpane biomarkers such as hopanes and steranes, are not present in the Haughton gypsum in sufficient quantities to have been readily detected.  相似文献   

DISCUSSION OF "Use of Geophysical Logs to Estimate Water Quality of Basal Pennsylvanian Sandstones, Southwestern Illinois," by V.L. Poole, K. Cartwright, and D. Leap, September-October 1989 issue, v. 27, no. 5, pp. 682–688     

John Logan 《Ground water》1990,28(1):118-119

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Northern Light on Global Warming: Henning Rodhe and Robert Charlson (eds.), The Legacy of Svante Arrhenius – Understanding the Greenhouse Effect     

John S. Perry 《Climatic change》1999,42(4):627-631

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