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Tham khảo tài liệu 'toefl ibt internet based test 2006 - 2007 part 74', ngoại ngữ, toefl - ielts - toeic phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | EXPLANATORY OR EXAMPLE ANSWERS AND AUDIO SCRIPTS FOR MODEL TESTS MODEL TEST 1 557 08 This is a stream that looks like the branches of a tree. Here s an example of a dendritic pattern. As you can see. it s similar to many systems in nature. In addition to the structure of a tree it also resembles the human circulation system. This is a very efficient drainage system because the overall length of any one branch is fairly short and there are many branches so that allows the water to flow quickly and efficiently from the source or sources. Okay let s look at the next example. Copyrighted matenal 558 ANSWERS AND AUDIO SCRIPTS FOR ACTIVITIES. QUIZZES. AND MODEL TESTS This drainage pattern is referred to as a radial pattern. Notice how the streams flow from a central point. This is usually a high mountain or a volcano. It kind of looks like the spokes that radiate out from the hub of a wheel. When we see a radial pattern we know that the area has experienced uplift and that the direction of the drainage is down the slopes of a relatively isolated central point. Going back to the dendritic for a moment. The pattern is determined by the direction of the slope of the land but it. uh the streams flow in more or less the same direction and . so it s unlike the radial that had multiple directions of flow from the highest point. Now this pattern is very different from either the dendritic or the radial 9 This is called a rectangular pattern and I think you can see why. Just look at all of those right-angle turns. The rectangle pattern is typical of a landscape that s been formed by fractured joints and faults. And because this broken rock is eroded more easily than unbroken rock stream beds are carved along the jointed bedrock. Copyrighted material EXPLANATORY OR EXAMPLE ANSWERS AND AUDIO SCRIPTS FOR MODEL TESTS MODEL TEST 1 559 Finally we have the trellis pattern. And here in this example you can see quite clearly how the tributaries of an almost parallel structure drain into .
