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61.
Charles Lyell, on his way to becoming a famous geologist, married Mary Horner in Bonn in July 1832; volume 3 of his ‘Principles of Geology’ was published by John Murray in London in May 1833. Between these two dates Lyell encountered the loess of the Rhine valley. The loess impressed Lyell and he included mentions of it in the Principles, first in 1833 and then, with some revised ideas, in volume 4 of the 4th edition published in 1835. Twelve editions of the Principles were published between 1830 and 1875 and it became one of the most important works in the development of geology, and made a major contribution to the worldwide spread of loess awareness. It is possible that Lyell was drawn to the loess because of its high molluscan content, he was particularly attracted to the study of shells.  相似文献   
62.
The International Union of Quaternary Research (INQUA) organized the study and consideration of the Quaternary Period (the last 2.6 million years in Earth’s history) via a set of commissions, sub-commissions, working groups, projects and programmes. One of the most successful and best records was the Loess Commission (LC) which functioned assub-commission and then commission from 1961 to 2003, resulting in 40 years of useful activity. The history of the LC can be divided into three phases: 1, from 1961–1977 when the President was Julius Fink; 2, from 1977–1991, with President Marton Pecsi; 3, from 1991–2003 with Presidents An Zhi-Sheng and Ian Smalley. Fink, from Vienna, and Pecsi, from Budapest, gave the LC a distinctly Central European aspect. The nature of loess in Central Europe influenced the nature of the LC but the settings for phases 1 and 2 were quite distinct. Phase 1 was a small scale academic operation, carried out in German. As phase 2 began in 1977 the scope expanded and Central Europe became a base for worldwide loess studies. where the LC language changed to English. Phase 2 was run from a National Geographical Institute and demonstrated a different approach to loess research, although the basic programmes of continent-wide mapping and stratigraphy remained the same. The Commission benefited from this change of style and emphasis. In phase 3 the administration moved away from Central Europe but the Finkian ethos remained solid.  相似文献   
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The Viking Orbiters imaged early morning, long, linear wave clouds along the flanks of the Tharsis volcanoes during late northern spring and early summer. These clouds are believed to be a product of either an atmospheric bore wave or a hydraulic jump generated by nightly katabatic winds. The Mars Regional Atmospheric Modeling System was used to study the interaction of the katabatic flows with the surrounding atmosphere to determine what mechanism is responsible for the clouds. Simulations at Ls=90°, 100°, 142°, 180°, 270°, and 358° were conducted focusing on the eastern flank of Olympus Mons. Model results compare well with Viking observations and closely approximate theoretical treatments of atmospheric bores. Strong downslope flows are simulated during the night, with a bore wave forming on and behind a well-defined katabatic front. The observed seasonality of the clouds was reproduced in the simulations; the bore was deeper and faster during northern summer and weakest during the winter. When the bore was strong, it was undular in form, and generated vertically propagating gravity waves in the atmosphere above. During the winter, the atmospheric structure was such that any gravity waves generated damped with height. Less atmospheric water vapor abundance during northern winter, as compared to the summer, is also a factor in the seasonality of the wave clouds. This study concludes that bore waves are the most likely mechanism for the generation of the observed linear wave clouds.  相似文献   
65.
We used two different methods of statistical analysis—cluster analysis and principal component analysis—to analyze the concentrations of principal chemical components (Si, Mg, Ca, Fe, Ni) and Co in ordinary chondrites. The analysis is based predominantly on published data (metadata). In total, chemical composition data from 646 ordinary chondrites were used in the statistical analysis. The aim of this analysis was to establish whether it would be possible or not to distinguish H, L, and LL chondrites based on the concentrations of major elements and Co in their bulk chemical compositions. It was also important to determine what conclusions such an analysis could enable to draw about matter differentiation in the formation environments of primordial parent bodies of particular ordinary chondrite groups (H, L, and LL). Another aim of the statistical analysis was to determine whether the distribution of Fe and Ni (with Co admixtures) is independent of petrographic types within particular groups of chondrites. This is of crucial importance for determining the distribution of FeNi(Co) ore occurrences in potential extraterrestrial deposits on modern asteroids—the sources of ordinary chondrites. The obtained results of statistical analyses confirmed that a clear-cut distinction between particular groups of ordinary chondrites is only possible for group H, while distinguishing L chondrites from LL chondrites is not always obvious. The results of the statistical analyses relating to the question of the possible existence of several primordial parent bodies (formation environments) of each group of ordinary chondrites are consistent with the results of contemporary astronomical spectroscopy research. What is particularly interesting is obtaining indications of the existence of common formation environments of the matter of L and LL chondrites, possibly on a few primordial parent bodies. The statistical analyses indicate that there is no correlation between the concentration of principal chemical components and the petrographic type of ordinary chondrites. This proves homogenous distributions of these elements within the parent bodies of each group of ordinary chondrites. Hence, the distribution of these elements in individual present-day asteroids is also homogenous.  相似文献   
66.
The latest operational version of the ECMWF seasonal forecasting system is described. It shows noticeably improved skill for sea surface temperature (SST) prediction compared with previous versions, particularly with respect to El Nino related variability. Substantial skill is shown for lead times up to 1?year, although at this range the spread in the ensemble forecast implies a loss of predictability large enough to account for most of the forecast error variance, suggesting only moderate scope for improving long range El Nino forecasts. At shorter ranges, particularly 3?C6?months, skill is still substantially below the model-estimated predictability limit. SST forecast skill is higher for more recent periods than earlier ones. Analysis shows that although various factors can affect scores in particular periods, the improvement from 1994 onwards seems to be robust, and is most plausibly due to improvements in the observing system made at that time. The improvement in forecast skill is most evident for 3-month forecasts starting in February, where predictions of NINO3.4 SST from 1994 to present have been almost without fault. It is argued that in situations where the impact of model error is small, the value of improved observational data can be seen most clearly. Significant skill is also shown in the equatorial Indian Ocean, although predictive skill in parts of the tropical Atlantic are relatively poor. SST forecast errors can be especially high in the Southern Ocean.  相似文献   
67.
We report the abundances and hydrogen-isotopic compositions (D/H ratios) of fatty acids extracted from hot-spring microbial mats in Yellowstone National Park. The terrestrial hydrothermal environment provides a useful system for studying D/H fractionations because the numerous microbial communities in and around the springs are visually distinct, separable, and less complex than those in many other aquatic environments. D/H fractionations between lipids and water ranged from −374‰ to +41‰ and showed systematic variations between different types of microbial communities. Lipids produced by chemoautotrophic hyperthermophilic bacteria, such as icosenoic acid (20:1), generally exhibited the largest and most variable fractionations from water (−374‰ to −165‰). This was in contrast to lipids characteristic of heterotrophs, such as branched, odd chain-length fatty acids, which had the smallest fractionations (−163‰ to +41‰). Mats dominated by photoautotrophs exhibited intermediate fractionations similar in magnitude to those expressed by higher plants. These data support the hypothesis that variations in lipid D/H are strongly influenced by central metabolic pathways. Shifts in the isotopic compositions of individual fatty acids across known ecological boundaries show that the isotopic signature of specific metabolisms can be recognized in modern environmental samples, and potentially recorded in ancient ones. Considering all sampled springs, the total range in D/H ratios is similar to that observed in marine sediments, suggesting that the trends observed here are not exclusive to the hydrothermal environment.  相似文献   
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69.
Despite the development of new measuring techniques, monitoring systems and advances in computer technology, rainfall-flow modelling is still a challenge. The reasons are multiple and fairly well known. They include the distributed, heterogeneous nature of the environmental variables affecting flow from the catchment. These are precipitation, evapotranspiration and in some seasons and catchments in Poland, snow melt also. This paper presents a review of work done on the calibration and validation of rainfall-runoff modelling, with a focus on the conceptual HBV model. We give a synthesis of the problems and propose a practical guide to the calibration and validation of rainfall-runoff models.  相似文献   
70.
The results of palaeomagnetic, rock magnetic, and microscopic study of Early Paleozoic metabasites and granulites from the Orlica?nie?nik Dome (OSD, Sudetes) have been combined with geochronological data. In the eastern part of the OSD (?nie?nik Massif, SM) ferrimagnetic pyrrhotite is prevalent, accompanied by various amounts of Fe-oxides. In the western part of the OSD (Orlica-Bystrzyca Massif, OBM) Fe-oxides dominate. All magnetic minerals originated during hydrothermal and weathering processes. The palaeomagnetic study revealed the presence of three secondary components of natural remanence: Late Carboniferous, Late Permian, and Mesozoic. Two Paleozoic components are related to volcanic activity in the Sudetes. They are carried by pyrrhotite and Fe-oxides and were isolated only in SM rocks. The Mesozoic component was determined in both parts of the OSD and is carried by Fe-oxides. It covers a time span, from ~160 to ~40 Ma, corresponding to a long period of alteration.  相似文献   
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