Unit 4: Weathering and erosion-Soil

Soil is a combination of ____, ____, and ____ which helps support the growth of plants

Mineral matter

Water

Air

What is the idealized soil profile, in order from top to bottom?

O horizon-Organic matter

A horizon-Organic and mineral matter (zone of loss or leeching)

E horizon-Little organic matter

B horizon-Mostly mineral matter (zone of accumulation)

C horizon-Unaltered and/or partially altered parent material

Both horizon O and A are considered to be the ____

Topsoil

What controls of soil formation can make soil become better developed?

• Parent material (parent sediment material gets deposited-soil likes thicker sediment layers)

• Time (Soil likes greater time)

• Climate (soil likes high heat/humidity)

• Organisms (soil likes more creatures)

  • Topography (soil likes to have a slight slope)

What are paelosols?

Ancient soils that are formed through burial

Friction opposes gravity therefore if the force of gravity is ____ to the force of friction there is ____

Equal or less than

No movement

What are important triggering factors that lower the angle of repose?

• Oversteepening of slopes

• Removal of anchoring vegetation

• Ground vibrations from earthquakes

  • Saturation of the material with water

What are the mass wasting types?

• Slump-rapid movement along a curved surface

• Rockslide-rapid movement of bedrock downslope

• Debris flow-rapid flow of debris with water

• Earthflow-rapid movement of water saturated soil

• Creep-slow movement of soil and sediment downslope

  • Solifluction-slow movement in areas underlain by permafrost

Match the following:

Dry sand grains ___ Increase the cohesion among sand grains

Small amounts of water ___ reduces friction and causes the sand to flow

Saturation ___ bound mainly by friction with one another

Dry sand grains-Bound mainly by friction with one another

Small amounts of water-Increases the cohesion among sand grains

Saturation-Reduces friction and causes the sand to flow