共查询到20条相似文献，搜索用时 31 毫秒
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Nathaniel W. Rutter 《地球表面变化过程与地形》1977,2(4):295-308
In 1971 and 1972, the Terrain Sciences Division of the Geological Survey of Canada carried out the largest mapping program in its history of the distribution and characteristics of terrain types. Over 140.000 mile2 (360,000 km2) of the Mackenzie Transportation Corridor was evaluated. This information was supplied to the public, industry and government in order to plan and design projects properly, by efficiently utilizing natural resources and minimizing environmental damage. The requirements of potential users varied to such a degree that it was decided to map the ‘basic’ geology and other terrain characteristics so that derivative maps could be constructed for specific uses. A mapping system was devised for surficial deposits using genesis as the primary unit, modified by texture and morphology. Organic and permafrost terrain were included, factors not ordinarily a part of traditional geological mapping. The system was comprehensive and flexible enough to include such aspects as the percentages of minor units, unit thickness, and slope and other morphological characteristics. In bedrock and unglaciated areas, a second system based upon the same principles as the first but arranged in a different manner was devised. In this case, the primary unit is based upon relief, with additional information on lithology of the bedrock, texture of overlying debris, and broad morphological and slope characteristics. Comprehensive legends were prepared. Using the mapping units as the base, the legends were divided into various categories, providing information on the composition, ground ice content, thickness, and engineering characteristics of the deposits, and surface characteristics including topography, drainage pattern, vegetation, and dominant soils (pedologic sense). 相似文献
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Obituary
Obituary Robert W. Pennak 相似文献8.
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Zinc, copper and cadmium were determined by atomic absorption spectrophotometry in zooplankton from the N. W. Mediterranean. Seasonal variations of metal concentrations in zooplankton as well as the dry weight of the samples and the salinities of surface seawaters were taken into consideration over two periods of 1 year each (1976 and 1978). Zooplankton samples, collected near the estuary of the River Var and near the sewage outfall of the town of Cannes, present higher values than those collected near Villefranche Bay. However, the range of our results appears to be in good agreement with the values reported in the literature for Mediterranean plankton. 相似文献
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The concentration levels of copper, zinc and cadmium in the coastal waters of the northwestern Mediterranean tend to match closely those of off-shore waters when there is no significant man-made contamination. The appearance of local high concentration for one metal by possible contamination does not necessarily correlate with high values for other metals, although some contamination sources elevate the concentrations of all three metals. In June 1974, the presence of a water mass having relatively high surface zinc-concentration was observed off the Marseille-Toulon area. 相似文献
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R.W. Girdler 《Physics of the Earth and Planetary Interiors》1983,33(4):328-329
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Tufas are widespread in the Napier Range of north Western Australia, an area of tropical seasonal climate and savanna vegetation. The major tufa deposits have been mapped and the different forms described. These include drapes on cliffs, cones at cave entrances or the mouths of ephemeral streams, rimstone pools, and tufa dams. There are at least two generations of tufa cone, with the older being heavily calcreted and eroded. Simple geochemical and petrographical data allow comparison between the different types of deposit here and with deposits from other parts of the world. Thin section observations and scanning electron microscopy enable an initial assessment of the role of organic processes in tufa formation. Obvious organic remains are sparse, although many of the active tufas are composed of filamentous microsparite fabrics, suggesting that algae have influenced the geometry of the deposits. However, the identification of various endolithic algae indicates that they may also be actively involved in the degradation of the deposits. 相似文献