Weathering and Soil with Erosion Contains: Weathering, The Nature of Soil, and Soil Erosion

1. Weathering and Soil
Notes Sheet

2. Section One Weathering
 Effects of Weathering- surface processes break down into smaller
pieces called sediments
 Mechanical Weathering- physical processes breaks rock into
fragments with the same chemical makeup and characteristics as the
original rock
Plant roots and burrowing animals cause mechanical weathering
Ice wedging- water enters cracks and freezes and expands, breaking rocks apart
Small pieces of rock have more surface area than the original rock and weather
faster

3. Section One Weathering
 Chemical Weathering- chemical reactions dissolve minerals in rocks
or change them into different minerals
Carbonic acid, formed from carbon dioxide gas and water, and plants acid can react
with minerals to weather rock
Oxidation- chemical process that occurs when iron is exposed to water and the
oxygen in the air
 Effects of Climate- pattern of weather that occurs in a particular area
over many years
Mechanical weathering is more rapid than chemical weathering in cold climates
Chemical weathering is more rapid than mechanical weathering in warm, wet
climates
Rock type can affect rate of weathering

4. Section Two The Nature of Soil
 Formation of Soil- can take thousands of years
Soil is a mixture of weathered rock, decayed organic matter, mineral fragments,
water, and soil
Formation is influenced by climate, slope, types of rock, types of vegetation, and
length of time that rock has been weathering
 Composition of Soil- the ingredients that make up soil
Clay, silt, and sand are small particles of sediments
Decaying, dark-colored plant and animal material called humus
Small spaces between soil particles my be filled with air or water

5. Section Two The Nature of Soil
 Soil Profile- made up of different layers of soil
Horizon A- top soil layer
• May be covered with organic litter that may turn into humus
• Fertile layer with more humus and less rock and mineral particles than
other soil horizons
Horizon B- middle soil layer
• Contains less hums and is lighter in color than Horizon A
• Minerals travel from Horizon A to Horizon B in a process called
leaching
Horizon C- bottom soil layer
• Has very little organic matter and is not strongly affected by
leaching
• Contains rock- the parent material of the soil
• Glaciers can deposit soil that did not form from the bedrock
beneath it

6. Section Two The Nature of Soil
 Soil Types- differ in different places
Different regions have different climates that affect soil development
Parent rock affects soil formation and types of vegetation that grows in a region
Time affects soil development because the longer the weathering has occurred, the
less the soil looks like the parent rock
Soil on steep slopes develop poorly

7. Section Three Soil Erosion
 Soil erosion or loss is important because plants do not grow as well
when topsoil is lost
 Causes and Effects of Erosion- many human activities disturb the
natural balance between soil production and soil erosion
Agricultural Cultivation- increased farming removes the plant cover, leaving soils
open to wind and water erosion
Forest Harvesting- removes forest which increases erosion and particularly damages
tropical rain forest soil
Overgrazing results when animals graze until almost all ground cover disappears
Urban Construction clear land of vegetation and removes soil

8. Section Three Soil Erosion
 Preventing Soil Erosion- soil must be protected
Manage crops
• Farmers plant shelter belts of trees to break the force of the wind
• Bare soil can be covered with decaying plants to hold soil in place
• Farmers graze animals on vegetation instead of plowing it under
• With no-till farming, plants stalks are left in the field to provide
cover for soil

9. Section Three Soil Erosion
Reduces erosion on slopes
• Contour farming reduces soil erosion by planting along the contours
of slops
• Terracing creates steep-sided flat areas for crops on the sides of
hills and mountains
Reduce erosion at construction sites
• Exposed ground is covered with mulch
• Water is sprayed onto bare soil to reduce wind erosion
• Topsoil is replaces and trees are planted
• Seeded areas are reinforced with netting or straw
• Steeper slopes are protected by retaining walls

10. Section Three Soil Erosion
Reduces erosion on slopes
• Contour farming reduces soil erosion by planting along the contours
of slops
• Terracing creates steep-sided flat areas for crops on the sides of
hills and mountains
Reduce erosion at construction sites
• Exposed ground is covered with mulch
• Water is sprayed onto bare soil to reduce wind erosion
• Topsoil is replaces and trees are planted
• Seeded areas are reinforced with netting or straw
• Steeper slopes are protected by retaining walls