Soil Formation and Mass Movements - Weebly
Transcript of Soil Formation and Mass Movements - Weebly
Soil Formation and
Mass Movements
Bellwork: Pg. 143-145
How does water cause mass movements?
How do earthquakes cause mass movements?
Soil Formation:
Climate determines soil
formation
Soil Formations
1. Tropical Climate
2.Dry Climate
3.Temperate Climate
Tropical
• Tropical (wet and warm) Climates make Laterite soils that are thick and infertile
1. Tropical
Rain washes away the A Horizon, but rotting vegetation covers the B Horizon
Laterite
2. Desert
•Desert (Dry) climates make soils from mechanical weathering •Soil is thin and mostly of parent rock (regolith)
3. Temperate
• Temperate (cool to warm) climates make 2 soils that depend on rainfall.
• Rain fall is not excessive
a. Pedalfer Soils – more than 65 cm of rain per year
ex: clay, quartz, iron
b. Pedocal Soils –less than 65 cm
of rain per year ex: calcium carbonate
3. Temperate
Pedalfer
Pedocal
Mass Movements Definition • The transportation of rock and soil down slope due to gravity
•Talus: a pile of rock fragments that accumulates at the base of the slope
•Together, weathering and mass movements
produce most landforms
•Streams and valleys are the most common landforms on earth
• Why?
• Most mass movements end up in a stream or valley
1.Water – heavy rain and snow saturate the ground
2. Oversteepened Slopes – angles 25 to 40 degrees will hold loose particles. If a slope is steeper than 40 degrees, slips become more likely.
3. Removal of Vegetation – plant roots attempt to stabilize
4. Earthquakes
Mass movements are based on 3 things:
1.Type of material that moves
2.How it moves
3.Speed of movement
Classification of Mass Movements
Types of Mass Movements…
1. Rockfall: rocks or fragments fall freely through the air =fast movement
•Common on steep slopes & can trigger other mass movements
2. Slide: material moves suddenly along flat, inclined surface
Rockslide: slides including segments of bedrock
Slumgullion landslide
Hinsdale County, Colorado
700 years old and still moving
3. Slump: downward movement of material along a curved surface
•Leaves a crescent-shaped cliff
A slump is a type of slope failure which involves
the rotational movement of soil or rock
4. Flows: materials containing large amounts of water
Earthflow – moves slowly
Mudflow – moves quickly
5. Creep: slowest type of mass movement. (freezing & thawing)