1. What are the two types of weathering? Define both.
The two types of weathering are mechanical and chemical. Mechanical weathering is the process by which
rocks are broken down physically. Chemical weathering is the process by which rocks break down
chemically.
2. What are the agents of mechanical and chemical weathering?
The agents of mechanical weathering are water, wind, abrasion, and living things such as plants and
animals. The agents of chemical agents are acid precipitation, acid in ground water, oxidation, and
acids in living things such as bacteria, lichen, fungi, and algae. [Water, oxygen, carbon dioxide, and acids]
3. How does ice wedging (frost action) break down rock?
Waters seeps into cracks of rock during warm weather, freezes and expands during cold weather, and
continues the cycle.
4. Explain how lichens break down rock.
Lichens attach to rocks. Weak acids produced by the plant begin to weaken the rock. As the rock is exposed
to the weak acid, the rock weathers over time.
5. How do acids in ground water cause caves to form?
Weak acids (carbonic or sulfuric acids) in groundwater react with rocks (limestone) in the ground causing a
chemical reaction to occur. Over a long period of time, the dissolving of the rock forms karst features such
as caverns.
6. What is oxidation? Where does oxidation occur?
Oxidation is a chemical reaction where an element such as iron is exposed to air causing an oxide to form,
such as rust. Oxidation more often occurs in warm, moist climates when left exposed for long periods of
time.
7. In what climate does chemical weathering occur the fastest?
Chemical weathering occur the fastest in warm, humid climates. EX: tropical rain forest
8. In what climate does mechanical weathering occur the fastest?
Mechanical weathering occur the fastest in cold, humid climates. EX: temperate forest – where I live
9. What is humus? Be specific.
Humus is the dark, organic material formed in soil from the decayed remains of plants and animals.
10. Why is humus so important to soil?
Humus provides the nutrients that many soils are missing and are important for plant growth.
11. What causes leaching?
Leaching is the movement of water through the horizons or soil layers. ( bedrock, clay, silt, sand)
12. What is soil fertility? Explain.
Soil fertility is the ability of soils to hold nutrients and share them with plants.
13. What is contour plowing and when is it used?
Contour plowing is a practice used in farming where they plow across the slope of a hill. This method is
used to prevent soil erosion and conserve rainfall. The rows act as a series of dams instead of a series of
rivers.
14. What is terracing and when is it used?
Terracing is used on steep hills to prevent erosion from heavy rains. This process changes one steep field
into several smaller, flatter fields.
15. What is no-till farming?
No-till farming prevents erosion by providing ground cover that reduces water run-off.
16. What are cover crops?
Cover crops are leafy green vegetation used between harvests to replace nutrients and to prevent soil
erosion.
17. How does crop rotation help soil?
By planting two different crops on the same plot of land, in alternating years, this allows the soil to recover
by slowing down the depletion of nutrients from the soil. This happens because different plants use
different nutrients.
18. What is differential weathering? Describe what happened to Devil’s tower.
Differential weathering is the process by which softer, less weather resistant rock wears away and leaves
harder, more weather resistant rocks behind. Devil’s Tower is the harder rock (granite) more resistant rock
left behind when the softer rock was weathered away.