Mass Movement
What force causes mass movement?
Gravity.
What are the four main components of soil?
Minerals, organic matter, water, air.
What is weathering?
The breaking down of rock at Earth’s surface.
What is the difference between creep and a landslide?
Creep is very slow movement.
Landslide is rapid movement downhill.
What is humus and where is it found?
Dark organic material from decayed plants and animals.
Found mostly in the O and A horizons.
What is the difference between mechanical and chemical weathering?
Mechanical changes size/shape but not composition.
Chemical changes the chemical makeup of the rock.
Explain how human activity can increase the risk of mass movement.
Removing vegetation, cutting into slopes, construction, and adding water can destabilize land.
Describe the O, A, and B soil horizons.
O: Organic layer (leaf litter, humus)
A: Topsoil (mix of minerals + humus)
B: Subsoil (minerals accumulate)
Name TWO factors that affect the rate of weathering and explain how one of them increases weathering.
Climate, surface area, rock type.
Example: Warm, wet climates increase chemical weathering.