Chapter 3 Review

2. wedging the process that splits rock when water seeps into cracks, then freezes and expands
6. The geologic principle that the same geologic processes that operate today operated in the past to change Earth's surface
8. rotation the planting of different crops in a field each year to maintain the soil's fertility
10. horizon a layer of soil that differs in color, texture, and composition
14. the solid layer of rock beneath the soil
15. the process of wearing down and carrying away rocks
16. the wearing away of rock by rock particles carried by water, ice, wind, or gravity
18. scale a measurement system that indicates acidity
20. consists of clay and other particles of rock, but little humus
21. a measure of how well the soil supports plant growth
22. the process that breaks down rock and other substances
23. conservation the management of soil to limit its destruction
24. soil that is made up of about equal parts of clay, sand, and silt

1. decayed organic material in soil
3. a crumbly, dark brown soil that is a mixture of humus, clay, and other materials
4. plowing plowing fields along the curves of a slope instead of in straight rows to prevent soil loss
5. resource anything in the environment that humans use
7. the loose, weathered material on Earth's surface in which plants can grow
9. plowing soil conservation method in which weeds and dead stalks from the previous year's crop are plowed into the ground.
11. weathering the type of weathering in which rock is physically broken into smaller pieces
12. the organisms that break the remains of dead organisms into smaller pieces and digest them with chemicals
13. when a material is full of tiny, connected air spaces that allow water to seep through it
17. the process where iron combines with oxygen in the presence of water - produces rust
19. weathering the process that breaks down rock through chemical change