14.6波浪沉积
Section outline
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Which came first: erosion or deposition?
::首先是侵蚀还是沉降?Both erosion and deposition are seen in this photo. The beach sands were deposited but waves are now eroding them away. At the shore, there's always a battle between the two types of forces. What happens when deposition is greater than erosion? What happens when erosion is greater than deposition?
::这张照片中既看到侵蚀,也看到沉积。海滩沙沙沉积,但海浪正在侵蚀它们。在海岸上,这两类力量之间总是有一场战斗。沉积大于侵蚀时会发生什么情况?侵蚀大于沉积时会发生什么情况?Wave Deposition
::波波沉积The transport of sediments by longshore currents is called longshore drift . Longshore drift is created in this way: Sediment is moved up the beach by an incoming wave. The wave approaches at an angle to the shore. Water then moves straight offshore. The sediment moves straight down the beach with it. The sediment is again picked up by a wave that is coming in at an angle. So longshore drift moves sediment along the shore. This zig-zag motion can be seen in Figure .
::深海洋流的沉积物迁移被称为远岸漂移。 远岸漂移以这种方式形成: 沉积物通过波浪向海滩移动。 海浪从一个角度向海岸移动。 水流随后直向近海移动。 沉积物随海流直向海滩移动。 沉积物再次被一个角度进入的波浪吸收。 因此, 远岸漂移会沿着海岸移动沉积物。 可见图中可见这种 zig-zag 运动 。Longshore drift carries particles of sand and rock down a coastline.
::远岸漂流带有沙子和岩石微粒沿着海岸线飘下。Landforms Deposited by Waves
::波浪所沉积的土地形态Longshore drift continually moves sand along the shore. Deposition occurs where the water motion slows. The smallest particles, such as silt and clay, are deposited away from shore. This is where the water is calmer. Larger particles are deposited onshore. This is where waves and other motions are strongest.
::远岸漂流不断沿海岸移动沙子。 沉降发生于水流减慢的地方。 最小的粒子, 如淤泥和粘土, 都沉落在岸外。 这是水比较平静的地方。 更大的粒子沉落在岸上。 这是海浪和其他运动最强的地方 。In relatively quiet areas along a shore, waves deposit sand. Sand forms a beach ( Figure ).
::沙沙形成海滩(图)。Manhattan Beach in Southern California has a pier coming off of a sandy beach.
::南加州的曼哈顿海滩 有个码头从沙滩上下来Waves also move sand from the beaches on shore to bars of sand offshore as the change. In the summer, waves have lower energy so they bring sand up onto the beach. In the winter, higher energy waves bring the sand back offshore.
::海浪还将沙子从岸边的海滩移到海边沙块,随着变化。 夏季,海浪的能量较低,因此沙子会带到海滩上。 冬季,高温的海浪将沙子带回岸外。Examples of features formed by wave-deposited sand.
::波浪沉积沙形成特征的例子。A spit is a ridge of sand that extends away from the shore. The end of the spit may hook around toward the quieter waters close to shore.
::吐口水是远离海岸的沙脊,吐口水的尽头可能绕到海岸附近的宁静水域。Waves may also deposit sediments to form sandbars and barrier islands . Pictured below are examples of these landforms ( Figure ); also, an example of all the different landforms waves create ( Figure ).
::波浪还可能沉积沉积物以形成沙条和屏障岛。 下面是这些土形的例子(图 ) ; 也是所有不同土形波形成的例子(图 )。A barrier island is a long strip of sand. The sand naturally moves in the local currents. People try to build on barrier islands.
::屏障岛是一片长长的沙地,沙地自然移动到当地的海流中,人们试图在屏障岛屿上建起。In its natural state, a barrier island acts as the first line of defense against storms such as . A natural barrier island is a vegetated sandy areas in which sand can move. When barrier islands are developed, hurricanes damage houses and businesses. A large hurricane brings massive problems to the urbanized area.
::在自然状态下,屏障岛是防暴的第一线,例如:天然屏障岛是可移动沙丘的植被沙地,在形成屏障岛时,飓风破坏房屋和商业,大飓风给城市化地区带来大量问题。Summary
::摘要- The shore may have a lot of sediment washed from land or eroded from cliffs. The sediment is transported by currents.
::海岸可能有许多从陆地冲出或从悬崖侵蚀的沉积物,沉积物由海流输送。
- Transported sand will eventually be deposited on beaches, spits, or barrier islands.
::运输的沙子最终将沉积在海滩、唾液或屏障岛屿上。
Review
::回顾- What processes cause spits and barrier islands to form?
::是什么过程导致唾液和障碍岛屿形成?
- What is longshore drift?
::什么是长岸漂移?
- Describe how sediment moves along the shore.
::描述沉积物如何沿海岸移动。
- What function does a barrier island in its natural state serve?
::隔离墙岛屿的自然状态有什么作用?
- The shore may have a lot of sediment washed from land or eroded from cliffs. The sediment is transported by currents.
