By: Adam Youssef
Mass Movements and disruptions in the environment can cause destruction or just move rocks and soil. Mass Movements is when rocks or soil are move downhill due to gravity. All of the following count as a type of mass movement. Landslides are large groups of soil and rock move downhill. Mudflows are ash (normally from a volcano) and water combining to create mud and moves downhill at tremendous speeds. Erosion (coastal erosion) is practically the wind and water carrying away small particles and weakening parts of the ground until it suddenly falls into the body of water. Floods carry away soil and sediments and deposit it somewhere ahead where the flood dies out.
Landslides and Mudslides
A landslide is when rock or soil slips very quickly down a slope. It is very dangerous. The factors of landslides are mass, gravity and water (rain, floods…). When rain is dropped onto the soil, the soil “sucks” it up. The liquid makes the soils mass greater and acts like extra weight. The gravity then pulls down the soil which starts to slip down the slope it is on. I believe that the steeper a slope the amount of time it takes for a complete landslide to end will shorten. I say so because the soil and/or rock will move faster and reach the valley a lot faster. Landslides break down mountains and/or hills and fills up nearby valleys. As the mountains start to break down, the valleys are getting filled with soil and rocks. The mountains will no longer be as steep and the valleys will start to become at the same level as the rest of the ground. Mudslides are when ash and water combine creating mud. The mud moves downhill and can reach up to 80 kilometers per hour. Mudslides usually happen when a volcano erupts only ash. If it rains right after the eruption then there will certainly be a mudslide. Mudslides can move and destroy large and heavy objects such as homes and cars. If there is a valley near the volcano, the mudslide will fill up the valley.
Link to a mudflow (information):
I believe this video is an excellent example of a land slide: http://www.youtube.com/watch?v=mknStAMia0Q
Floods and Coastal Erosion
Coastal Erosion can cause part of the coast to fall into the water. The land is weakened by the water and the wind. Erosion's main factor is moving water. The water weakens the soil and the wind takes/carries some soil along. The wind and water‘s process continues and after sometime, a part of the coast shall fall into the sea. The soil “loses its grip”. This starts to remove parts of land and makes landmasses smaller. It is also making the sea level rise. Whenever coastal erosion occurs, the sea level starts to rise. Floods can also break down the ground. As, the water (the cause) is running, it picks up soil, rocks and sediments. The water picks up the soil and sediments and drops it off somewhere else where the flood dies out/ends. When the flood is picking up sediments, the higher ground slowly starts to get lower and lower. Runoff (moving water on the ground) also picks up soil. Runoff could also lead to floods. The amount of runoff depends on 5 factors:
1. Amount of Rain
2. Vegetation
3. Type of Soil
4. Shape of Land
5. How the land is used by mankind
If there is more runoff, it means there is more erosion. As runoff is occurring, it creates long narrow paths in the soil which are called rills. There is an area where the rills start to join together and form a larger groove (narrow path) called a gully. Gullies get larger as water continues flowing through it and carrying away soil and rocks. The gully is being eroded and growing bigger. Gullies contain water only after rainfall. Next, gullies will meet at a certain point and make an even bigger groove which is call a stream. Streams rarely dry up. Other names for streams are creeks and brooks. The streams (sometimes) will combine and create a bigger stream, and sometimes, these streams are big enough to count as a river. Finally, the river will receive water from tributaries. Tributaries are streams that and/or rivers that flow into another river.
Here is an example of floods:
Example of Coastal Erosion: http://www.youtube.com/watch?v=ITv6gSUmTjc
All mass movements shape and “twist” the world in a way. Some of the mass movements relate to each other while others are very similar. Some changes the land in similar ways (fill up or empty). These phenomenons only count as dangerous is when they affect humankind (in a bad way). All mass movements happen wherever there is a downhill slope (steep or flat).
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