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正The Abstracts of Chinese Geological Literatureis edited and published by China Geological Library with an aim to provide bibliographic information to foreign geological circles on Chinese geological literature.The Abstracts is published in four numbers per annum.It gives 相似文献
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Edge loaded annular foundations have been analysed assuming the soil pressure at the contact to be non-uniform using the lower bound approach of Limit Analysis. Variable fixity at the edges has been allowed and the foundation slab is made to follow the Square yield criterion. Results presented in the form of curves can be readily used to obtain the locations of the yield hinge circles for the given slab and the corresponding collapse load. © 1997 John Wiley & Sons, Ltd. 相似文献
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Rafael C. Carvalho David M. Kennedy Yakufu Niyazi Chloe Leach Teresa M. Konlechner Daniel Ierodiaconou 《地球表面变化过程与地形》2020,45(11):2540-2555
Historical aerial photographs are an invaluable tool in shoreline mapping and change detection in coastal landscapes. We evaluate the extent to which structure-from-motion (SfM) photogrammetric methods can be applied to quantify volumetric changes along sandy beaches, using archival imagery. We demonstrate the application of SfM-derived digital surface models (DSMs) at East Beach and Lady Bay in southwest Victoria, Australia, using photographic datasets taken in 1969, 1977 and 1986, and compare them to LiDAR-derived DSMs acquired at both sites in 2007. The SfM approaches resulted in two entire and two partial suitable DSMs out of six datasets. Good-quality DSMs were spatially continuous with a good spread of ground control points (GCPs) near the beach at Lady Bay, whereas unsuitable DSMs were mostly restricted by poor distribution and number of GCPs in spatially segmented areas of East Beach, due to limited overlapping of images, possible poor quality of GCPs and also the propagation of errors in the derived point clouds. A volume of approximately 223 000 ± 72 000 m3 was deposited at Lady Bay between 1969 and 2007, despite minimal erosion observed near the breakwater. The partially suitable dataset of East Beach indicated that beach erosion of at least 39 m3 m−1 occurred immediately to the east of the seawall after 1977. We also discuss the drawbacks and strengths of SfM approaches as a benchmark of historical erosion assessments along sandy beaches. © 2020 John Wiley & Sons, Ltd. 相似文献
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Deborah L. Elliott-Fisk 《自然地理学》2013,34(4):299-323
The White Mountains, astride the California-Nevada stateline, are the highest and westernmost of the Great Basin ranges. This range was extensively glaciated during the Quaternary Period. Glacial landforms and scattered erratics were identified in the field using primarily morpho-and lithostratigraphic criteria, and mapped on aerial photographs and topographic maps. Topographic characteristics of the glacial deposits were analyzed using standard statistical procedures. A sequence of glacial deposits was identified in terms of six glacial stages, these glaciations named according to type site, and relative ages inferred. With the exception of perched Stage I (early) deposits along the range crest, reconstructed equilibrium-line altitudes and elevation of the glacier termini increase to the present, with glacier length and inferred size decreasing through time. Preliminary data suggest that weathering and pedogenesis are also progressive, though environmental gradients mask some of these distinctions between deposits. It is hypothesized that the White Mountains have a similar glacial chronology to the adjacent Sierra Nevada, but that with the intensification of the Sierran rainshadow during the Quaternary, the extent of glaciation in the White Mountains apparently decreased through time owing to regional tectonic uplift. This had led to the preservation of a more complete sequence of glacial deposits than in the Sierra Nevada, making the delineation of multiple mid-Quaternary events possible in many valleys. Further radiometric and chronometric dating of these deposits is in progress. [Key words: Glaciation, Quaternary, glacial geomorphology, White Mountains, California, Nevada. 相似文献
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SCHMIDT‐HAMMER EXPOSURE AGES FROM PERIGLACIAL PATTERNED GROUND (SORTED CIRCLES) IN JOTUNHEIMEN,NORWAY, AND THEIR INTERPRETATIVE PROBLEMS 
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下载免费PDF全文 STEFAN WINKLER JOHN A. MATTHEWS RICHARD W. MOURNE PETER WILSON 《Geografiska Annaler: Series A, Physical Geography》2016,98(3):265-285
Periglacial patterned ground (sorted circles and polygons) along an altitudinal profile at Juvflya in central Jotunheimen, southern Norway, is investigated using Schmidt‐hammer exposure‐age dating (SHD). The patterned ground surfaces exhibit R‐value distributions with platycurtic modes, broad plateaus, narrow tails, and a negative skew. Sample sites located between 1500 and 1925 m a.s.l. indicate a distinct altitudinal gradient of increasing mean R‐values towards higher altitudes interpreted as a chronological function. An established regional SHD calibration curve for Jotunheimen yielded mean boulder exposure ages in the range 6910 ± 510 to 8240 ± 495 years ago. These SHD ages are indicative of the timing of patterned ground formation, representing minimum ages for active boulder upfreezing and maximum ages for the stabilization of boulders in the encircling gutters. Despite uncertainties associated with the calibration curve and the age distribution of the boulders, the early‐Holocene age of the patterned ground surfaces, the apparent cessation of major activity during the Holocene Thermal Maximum (HTM) and continuing lack of late‐Holocene activity clarify existing understanding of the process dynamics and palaeoclimatic significance of large‐scale sorted patterned ground as an indicator of a permafrost environment. The interpretation of SHD ages from patterned ground surfaces remains challenging, however, owing to their diachronous nature, the potential for a complex history of formation, and the influence of local, non‐climatic factors. 相似文献
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河南省城市体系功能组织研究 总被引：8，自引：0，他引：8
本文通过分析河南省城市体系功能组织的区域背景,提出了“一点三圈”式设想,并在明确城市体系等级层次的基础上,论述了首位城市郑州和核心城市圈、中间城市圈、周边城市圈的功能组织方式。 相似文献
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Analyses of deterioration of the Cappadocian tuff, Turkey 总被引：8，自引：3，他引：5
The Cappadocian tuff contains unique erosional features, the so-called fairy chimneys, some of which in the past were dwelled
in and contain valuable wall paintings. These historical heritages, however, are undergoing chemical and physical deterioration
due to atmospheric effects. For the conservation studies, understanding of the deterioration phenomenon of the tuff is essential.
In this study, engineering geological and physicochemical characteristics of the tuff were determined. The durability of the
tuff was assessed through wetting-drying, freezing-thawing, and salt crystallization. The test results suggest that chemical
weathering may be traced to a depth of 2 cm below lichen-covered surfaces and 20 cm adjacent to discolored joint walls. Based
on durability assessment methods, the tuff may be classified as having poor to very poor durability.
Received: 16 December 1996 · Accepted: 3 April 1997 相似文献
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The origin of the so-called “fairy circles” has not yet been established. Carbon monoxide (as an indicator of a natural gas microseep) was monitored inside and outside of the selected fairy circles in the Namib, Namibia, Southern Africa. Hydrocarbons were extracted from the soil by a novel method for trapping analytes onto silicone rubber designed for thermal desorption into a gas chromatograph-mass spectrometer (GC-MS). Unresolved complex mixtures with resolvable alkanes were detected in soil collected from two newly formed circles. Alkenes, the microbial degradation product of alkanes (microbial food source), were more abundant in the circles compared to the levels of alkenes detected in the matrix between circles. Results show a microseepage of gases and hydrocarbons which is expressed at the surface as a geobotanical anomaly of barren circles and circles of altered vegetation. In addition, this finding may suggest a new approach to the origin of the mima mounds (heuweltjies) of the Western Cape in South Africa. 相似文献
10.
WANG Bo GUO Qinghai Dou Sen 《中国地理科学(英文版)》2006,16(4):359-364
1 Introduction It is indisputable that the urbanization has been consid- ered as an important indicator for evaluating a nation’s or a region’s modernization and industrialization. Therefore, the issue of urbanization will arouse wide and remarkable concern in both domestic and international geography in the 21st century. From a comprehensive survey of the development of urbanization all over the world, some successful modes of urbanization, such as the American mode and the Japanese mode, … 相似文献