Unit 7: Weathering, Erosion, and Soil- ANSWER KEY
1. Broken up rocks and minerals along with dead plants and animals are the
ingredients of soil.
2. Good soil does more than just grow crops. It also provides homes for animals,
storage for water, and nutrients for plants.
3. Draw and label all of the horizons in a soil profile.
4. Subsoil is horizon B, Bedrock is horizon C, and Topsoil is horizon A.
5. Dead plant and animal material in soil is also known as humus.
6. Of the three horizons, horizon A has the best soil and horizon C has the worst
soil.
7. The three types of soil are sandy, clay, and loamy
8. The type of soil that is best for drainage is sandy and the best type for growing
crops is loamy.
9. The following human activities damage healthy soil: deep tilling, strip mining,
overgrazing cattle, and undergrazing cattle.
10. Soil is a non-renewable resource. If humans keep misusing it, desertification,
nutrient depletion of soil, and mass wasting can occur.
11. Farmers should alternate the types of things they grow from year to year. This
is known as crop rotation and it helps to reduce nutrient depletion.
12. Progressive farmers utilize windbreaks, contour plowing, and shallow tilling to
protect the soil on their farms.
13. Contour plowing means driving your tractor and plowing across the slope of a
hill.
14. The movement of a large amount of dirt down hill is known as mass wasting or
mass movement.
15. Examples of large amounts of topsoil moving downhill are mudflow, rock
slides, and creep.
16. The slowest type of mass movement is creep.
17. One simple way to keep soil healthy is to ensure that the soil is never bare.
That means keeping plants in dirt for as long as possible.
18. Dirt is extremely valuable. It is responsible for all of the food that people eat.
Soil is considered to be a non-renewable resource because if we do not use good
farming technique, we will run out of topsoil.
19. Stopping the erosion of topsoil is a top priority of farmers and soil
conservationists. Six strategies that are utilized include crop rotation, ground cover,
shallow tilling, windbreak, terrace, and contour plowing.
20. Weathering is the breaking apart of rock.
21. The three types of weathering are mechanical, chemical, and biological.
22. Mechanical weathering is breaking down rocks by physical force.
23. The roads in the northern part of America are damaged every winter because of
ice wedging. This occurs when water seeps into cracks in the road, freezes and
expands, and the road is damaged. This is an example of mechanical weathering.
24. Breaking rocks apart by living organisms is called biological weathering.
Animal burrows, animal paths, and roots are examples of this action.
25. The breaking apart of rocks because of chemical reactions is called chemical
weathering..
26. A plant that breaks apart rocks because of acids that it produces is called lichen.
27. Chemical weathering occurs when slightly acidic rain water dissolves slightly
basic rocks.
28. The dirt on Mars is red because of rust / oxidation. This is an example of
chemical weathering.
29. Chemical weathering/dissolution is a term that describes how acids break apart
rocks.
30. Chemical weathering/hydrolysis refers to a chemical change to a substance
when it interacts with water.
31. Dirt from mountain tops can be carried downhill to fill in valleys. This is
called deposition.
32. Human intervention can increase and decrease erosion.
33. Wind, water, and gravity all combine to move dirt around. Of the three, water
is responsible for moving the most amount of soil. This is known as erosion.
34. The agent of erosion that carries the largest rocks is glaciers.
35. The type of erosion that carries away most sand at Tybee Island is waves. This
is called mechanical weathering.
VOCABULARY
chemical weathering
biological weathering
mechanical weathering
erosion
deposition
soil horizon
horizon A
horizon B
horizon C
dissolution
hydrolysis