中间图

Or

雷哥网GMAT>题库>精选题库>阅读RC>16074

阅读RC-16074 (第1/4题) Time Cost00:00
收藏
报告题目错误
请选择错误类型:
请描述一下这个错误:

取消

No very satisfactory account of the mechanism that caused the formation of the ocean basins has yet been given. The traditional view supposes that the upper mantle of the earth behaves as a liquid when it is subjected to small forces for long periods and that differences in temperature under oceans and continents are sufficient to produce convection in the mantle of the earth with rising convection currents under the mid-ocean ridges and sinking currents under the continents. Theoretically, this convection would carry the continental plates along as though they were on a conveyor belt and would provide the forces needed to produce the split that occurs along the ridge. This view may be correct: it has the advantage that the currents are driven by temperature differences that themselves depend on the position of the continents. Such a back-coupling, in which the position of the moving plate has an impact on the forces that move it,could produce complicated and varying motions.

On the other hand, the theory is implausible because convection does not normally occur along lines. and it certainly does not occur along lines broken by frequent offsets or changes in direction, as the ridge is. Also it is difficult to see how the theory applies to the plate between the Mid-Atlantic Ridge and the ridge in the Indian Ocean. This plate is growing on both sides, and since there is no intermediate trench, the two ridges must be moving apart. It would be odd if the rising convection currents kept exact pace with them. An alternative theory is that the sinking part of the plate, which is denser than the hotter surrounding mantle, pulls the rest of the plate after it. Again it is difficult to see how this applies to the ridge in the South Atlantic, where neither the African nor the American plate has a sinking part.

Another possibility is that the sinking plate cools the neighboring mantle and produces convection currents that move the plates. This last theory is attractive because it gives some hope of explaining the enclosed seas, such as the Sea of Japan. These seas have a typical oceanic floor, except that the floor is overlaid by several kilometers of sediment. Their floors have probably been sinking for long periods. It seems possible that a sinking current of cooled mantle material on the upper side of the plate might be the cause of such deep basins. The enclosed seas are an important feature of the earth's surface, and seriously require explanation in because, addition to the enclosed seas that are developing at present behind island arcs, there are a number of older ones of possibly similar origin, such as the Gulf of Mexico, the Black Sea, and perhaps the North Sea.

According to the traditional view of the origin of the ocean basins, which of the following is sufficient to move the continental plates?


  • 分析A选项
    xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
  • 分析B选项
    xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
  • 分析C选项
    xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
  • 分析D选项
    xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
  • 分析E选项
    xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
暂无雷哥网文字解析
当前还没有完善解析,欢迎在这里提交你的解答,等待老师审核~

题目讨论 (1条评论)

用户头像
提交
  • 用户头像
    liao8520

    P1:
    differences in temperature under oceans and continents are sufficient to produce convection
    this convection would carry the continental plates
    0 0 回复 2018-08-27 10:14:41
    题号选择

    科目: 阅读RC

    • 句子改错SC
    • 逻辑CR
    • 阅读RC
    • 数据充分DS
    • 问题求解PS
    • 综合推理IR

    来源: 精选题库

    • 全部
    • OG20
    • OG20新题
    • OG19新题
    • OG18新题
    • OG18分册
    • OG17新题
    • OG16
    • OG12
    • 破解版12
    • 破解版08
    • 破解版07
    • GWD
    • 精选题库
    • OG18自测章
    • Manhattan
    • magoosh
    • 难题300
    本题信息

    2m16s

    平均耗时

    88%

    平均正确率

    • 题目来源1:精选题库

    该题由网友GiF6jY提供 上传GMAT题

    • 手机注册
    • 邮箱注册
    登录>







    关闭图标

    标题图

    • 图标

      知识库学习

      GMAT语法、逻辑、阅读、数学各单项备考知识点学习及测验
    • 图标

      在线做题

      包含GMAT各单项必考知识点题目、OG/PREP/GWD/雷哥讲义题目、难度650/680/700/730题库题目练习及题目解析
    • 图标

      在线模考

      语文套题/数学套题/全套仿真模考,包含GWD/PERP/精选模考等上百套套题模考
    • 图标

      在线测评

      适合5种不同基础的GMAT学员,测评后可自动出具分数报告及复习计划指导
    • 图标

      资料下载

      GMAT必备备考资料下载、鸡精下载、课程课件等免费下载
    • 图标

      课程学习

      注册会员后,可在GMAT课程区,选择免费直播课程及公开课程进行在线学习
    ×
    请你选择你要查看的模考成绩单
    立即开通 暂不开通
    加载图片
    网络异常