Chapter 2

5. the process that breaks down rocks through chemical changes
7. operated in the past to change the Earths surface
10. a line on a topographic map that connects points of equal Evevation
11. a loose weathered material on earths surface in which plants can grow
12. the difference in elevation from one contour line to the next
13. the layer of soil that differs in color and texture from the layers above it and below it
14. a chemical change in which a substance combines with oxygen, as well iron oxidates, forming rust
15. soil organisms that break down the remains of organisms and digest them
16. the solid layer beneath the soil
17. the process by which water,Ice,wind, or gravity moves weathered rock and soil
19. soil conversation method in which dead stalks from the previous years crop are left in the ground to hold the soil in place
24. anything in the environment that humans use
25. the grinding away of rock by other rock particles carried in water,ice, or wind
27. a map that shows surface features of an area
29. mixture of humus,clay,and other minerals that forms the crumbly, topmost layer of soil

1. a heavier line that is labeled with the elevation of that contour line in round units
2. the chemical and physical processes that break down rock at earths surface
3. a measure of how much soil supports plant growth
4. the type of weathering in which rock is physically broken into smaller pieces
5. the planting of different crops in a field each year to maintain the soils fertitly
6. dark colored organic material that's in the soil
8. process that splits rock when water seeps into cracks, then freezes and expands
9. the loose layer of dead plant leaves and stems on the surface of the soil
18. the magenament of soil to prevent its destruction
20. a thick mass of grass roots and soil
21. the layer of soil beneath the topsoil that contains mostly clay and other minerals
22. plowing fields along the curves of a slope to prevent soil loss
23. the area of the Great Plains where wind erosion cause soil loss during the 1930's
26. rich,fertile soil that is made up of about equal parts of clay, sand and silt
28. characteristic of a material that is full of tiny, connected air spaces that water can seep through