l环境科学与工程专业英语Erosion.ppt

Erosion 土壤剖面结构 TEXT Erosion is an important natural process, rusulting in the redistribution of the products of geologic weathering, and is part of both soil formation and soil loss.The worlds landscapes have sculpted(雕刻） by erosion. When the results are spectacular enough, we enshrine（铭记） them in national parks as we did with the Grand Canyon（峡谷）. Where erosion has worn down mountains and spread soil over the plains, or deposited rich alluvial silt in river bottomes, we galdly farm it. Erosion is a disaster only when it occurs in the wrong place at the wrong time. Erosion is an important natural process, rusulting in the redistribution of the products of geologic weathering, and is part of both soil formation and soil loss. 侵蚀是一个重要的自然过程，它导致了地质风化的产物的重新分配，是土壤形成和流失的部分原因。 The worlds landscapes have sculpted(雕刻） by erosion. 世界的地形和地貌就是由于侵蚀的作用而形成的。 When the results are spectacular enough, we enshrine（铭记） them in national parks as we did with the Grand Canyon. 有时候，侵蚀的效果如此壮观，以至于我们用国家公园把它铭记下来，如美国的大峡谷。 Where erosion has worn down mountains and spread soil over the plains, or deposited rich alluvial silt in river bottomes, we galdly farm it. 当侵蚀慢慢磨损了山脉，并使平原覆盖了土壤，或者在河流底部形成富饶的底泥，人们会非常高兴有了可耕地。 Erosion is a disaster only when it occurs in the wrong place at the wrong time. 只有当侵蚀在错误的时间和错误的地方发生时，它才会成为一种灾难。 In some places, erosion occurs so rapidly that anyone can see it happen. Deep gullies（冲沟） are created where water scours away（冲刷） the soil, leaving fence posts and trees sitting on tall pedestals（地基） as the land erodes away around them.In most places, however, erosion is subtler（微妙的）. It is a creeping disaster that occurs in small increments（增量）. A thin layer of top soil is washed off fields year after year until eventually nothing is left but poor-quality sub-soil that requires more and more fertilizer and water to produce any crop at all. In some places, erosion occurs so rapidly that anyone can see it happen. 在某些地区，侵蚀的速度是如此之快，任何一个人都可以看见它的发生。 Deep gullies are created wh