环境地质学第四章

地球表层的塑造过程
环境地质学 Environmental Geology
Part three
Mass Wasting Processes Creep Creep may be caused by numerous phenomena. For example, in terrains subject to frost, rock or soil may get heaved up perpendicular to the slope upon freezing, and returned vertically downward during a thaw. Thus, over time, material on a slope is likely to move downhill. Microlandslides and random movements such as overturned trees, etc., all contribute to creep.
地球表层的塑造过程
环境地质学 Environmental Geology
Part three
Mass Wasting Processes Creep Creep is the slow, downslope movement of soil, weathered rock, or other surficial debris. Movement is by quasiviscous flow, occurring under shear stresses sufficient to produce permanent deformation, but too small to result in a discrete failure surface such as a landslide.
地球表层的塑造过程
Part three
Mass Wasting Processes Landslides Landslide activity typically increases after prolonged rains, or after the frost leaves the ground in the spring. The novelist Firtsch (1980) describes the ominous hazard of landslides which weighs heavily on the minds of people who live in the steep slopes of the Swiss Alps:
环境地质学
Environmental Geology
环境地质学 Environmental Geology
Part three
பைடு நூலகம்
地球表层的塑造过程
6、Pre降水、江河与洪水 Pre降水、 降水 7、Mass Wasting Processes 表层整体再塑 （滑坡、泥石流、溶蚀、塌陷） 滑坡、泥石流、溶蚀、塌陷） 8、海岸线与海岸塑造过程 9、生态与植被
地球表层的塑造过程
There is nothing inorganic.... The earth is not a mere fragment of dead history, stratum upon stratum like the leaves of a book, to be studied by geologists and antiquaries古玩家 chiefly, but living poetry like the leaves of a tree, which precedes flowers and fruit-not a fossil earth, but a living earth.... Henry David Thoreau
地球表层的塑造过程
Part three
Mass Wasting Processes Rockfall Talus will not rest at an angle greater than the angle of repose. The angle of repose is measured similarly to dip of sedimentary rocks, i.e., from the horizontal, and is typically about 33-35°. Bedrock composition, as well as talus particle size, angularity, and sorting, has some effect on the angle of repose; large angular boulders may rest at up to 40°. The angle of repose of open-pit mine waste rock is approximately 38°.
环境地质学 Environmental Geology
Part three
Mass Wasting Processes
地球表层的塑造过程
环境地质学 Environmental Geology
Part three
Mass Wasting Processes Rockfall Rockfall occurs where a cliff of bedrock is exposed to weathering and pieces of the bedrock are pried loose and fall, bounce, or roll to rest at the base of the cliff. The resulting deposit is called talus崩塌岩堆 (Behre, 1933; Schumm and Chorley, 1966; Rapp, 1976). In an irregularly eroded cliff, talus cones may develop in the gully冲沟 head areas (Fig.6.2). In more extensive cliffs, coalescing聚集 talus cones form a more continuous blanket of debris referred to as scree 山麓碎 石(Jeffreys, 1932; Adrews, 1961). 环境地质学 Environmental Geology
环境地质学 Environmental Geology
Part three
Mass Wasting Processes
地球表层的塑造过程
A、Flowing sand, landslides, and rock falls are examples of mass wasting, the general term for gravitationally induced downslope movement of debris. B、Mass-wasting processes operate on sloping lands; eventually the debris reaches a stream or gully where fluvial processes continue the erosional process.
环境地质学 Environmental Geology
Part three
地球表层的塑造过程
7、Mass Wasting Processes
表层整体再塑
（滑坡、泥石流、溶蚀、塌陷） 滑坡、泥石流、溶蚀、塌陷）
环境地质学 Environmental Geology
Part three
Mass Wasting Processes
地球表层的塑造过程
环境地质学 Environmental Geology
Part three
Mass Wasting Processes Landslides Landslide is the process whereby a distinct mass of rock or soil moves downslope due to gravity. Landslides, unlike creep, have one or more distinct failure surfaces. Landslide velocities are typically on the order of 1 m/day to perhaps 300 km/hr as in the special case of airentrapped landslides generated by earthquakes. Shreve (1968) believes that the prehistoric Blackhawk Landslide in California slid at immense speeds on a layer of compressed air that was trapped beneath the debris. The landslide, consisting of 320 million m3, traveled 8 km across a desert floor at an average slope of 2.5°. [Hsu ° (1975) challenges the airlubrication 空气润滑 hypothesis假说 in favor of 假说 a debris flow mobilized by collision of particles within a dust-laden cloud.]. 环境地质学 Environmental Geology
地球表层的塑造过程
环境地质学 Environmental Geology
Part three
Mass Wasting Processes One of the world's most famous talus slopes is the one which formed an impedment障碍 to 障碍 prospectors开拓者 during 开拓者 the Klondike gold rush of 1898. the snow-covered talus slope, called the Scales, was the only access to Chilkoot Pass and the Yukon River. The pass was guarded by the Canadian Northeast Police, who required every prospector to carry 1 ton of supplies up the slope and into the interior.
地球表层的塑造过程
环境地质学 Environmental Geology
Part three
Mass Wasting Processes Rockfall One of the world's most famous talus slopes is the one which formed an impedment障碍 to prospectors开拓者 during the Klondike gold rush of 1898. the snow-covered talus slope, called the Scales, was the only access to Chilkoot Pass and the Yukon River. The pass was guarded by the Canadian Northeast Police, who required every prospector to carry 1 ton of supplies up the slope and into the interior.