机构地区: 华南师范大学
出 处: 《热带地理》 2000年第3期243-246,共4页
摘 要: 发达的花岗岩节理和丰富的年降水量是揭西石肚溪、丰顺龙鲸河等粤东近海山区河流壶穴地貌发育的基础。“冰臼论”提出的在冰裂隙中形成的“滚流”、“圆柱体水砧”等流体形式只不过是一种主观臆断。石肚溪的宽谷———峡谷相间的河谷形势及龙鲸河的谷中谷现象是地壳间歇式上升造成河流的侧蚀和下切作用相互交替的结果 ,宽谷 (或U形谷 )并不一定就是冰川谷。分布于河床上或谷坡上的花岗岩巨块是花岗岩巨型球状风化产物被洪水从上游带来或从谷坡两侧滚落入谷底和残积于谷坡上所致 ,它们不一定是古代的冰飘砾 ,也不会是冰缘作用形成的石海。 Crisscross joints in the granite and abundant annual rainfall are the basic conditions for the pot-holes developed on the river bed rock in the Shidu River, Jiexi County and Longjing River, Fengshun County. The so-called “Rolling current” and “Drilling head of water cylinder” are just an assumption advanced by the authors of “Moulin Theory”. The layout situation of wide-valleys alternating with gorges of Shidu River and gorge-in-valley of Longjing River can be attributable to the lateral erosion alternating with downcutting of the two rivers as a result of the intermittent uplift of the crust. A wide valley (or U-shaped valley) may not necessarily be a glaciated valley. Hughe stone blocks on river beds carried from upstream by floods or rolling down from the valley sides and those which have been the residua on slopes are the products of granite of spherical weathering, they might neither be ancient glacial drift boulders nor block field of glacial marginal deposits.
领 域: [天文地球]