The Pull of Gravity is stronger than you think
What is Mass Movement
- Is the Movement of a large mass of rock, soil and debris downward due to the pull of gravity
- Mass movement is a type of erosion capable of making huge changes to the side of a mountain
- can happen quickly or slowly
- the term landslide is often used but does not fully cover the different triggers and types of erosion of this scale.
Causes of Mass Movement
- Gravity is constantly trying o pull rock and debris down the slope of a mountain, at the same time the mountains resistive force/ sheer strength is pulling against the gravity
- Causes of mass movement occur when gravitational force overcomes the resisitive forces of the mountain.
- Increased slope steepness in a mountain increases the chance of mass movement
- increased water is another factor, as water can wash away particles that keep the mountain side intact.
- Vegetation also impacts mass movement as the roots anchor the soil particles.
- Earthquakes plays a role in mass movement as the violent shaking can break off sections of mountains, causing them to slide down the slope
Slumps and Rockslides
- One of the types of mass movement that is an example of the slope failing is a slump, the sliding of coherent rock material along a curved surface, for example water might erode the base of a cliff. Without the base the outer sections of the mountains slumps down as a unit
- A rockslide is the sliding of rock material down a mountain, it is similiar to a slump, but a rockslide does not move along a curved surface. In a rockslide we see rocks sliding down a pre existing surface as a result we will see a collection of fallen rocks at the base of a rockslide.
Landslides-What they are & their causes
Debris flow and Earthflow
- Other types of mass movement involve the downward movement of unconsolidated materials (weak materials)
- They are known as Debris flow and Earthflow as the material flows like liquid down a slope
- Movement of water-laden mass of loose mud, sand, soil, rock and debris down a slope
- Some debris can fall slowly and others reach 100km/h sweeping anything in their, effectively making more debris
- Flow of fine grained material that typically develops at the lower end of a slope.
- When fine grained materials (clay, silt) become exposed to water they become prone to earthflows
- More water= More speed
Geomorphology 5: Mass Movements