soil world

4. the decaying organic matter in soil
5. weathering breakdown or decomposition of rock that takes place when minerals change through chemical processes
7. the size, shape, and position of the particles of soil
8. the process by which natural forces break down rocks and soil
9. the top layer of soil that contains humus
10. weathering the breakdown of rock into smaller pieces of the same material without any change to its composition
11. the ability to let water pass through
14. a chemical reaction in which an element combines with oxygen to form an oxide; iron oxide = rust
15. the makeup of rock or soil describing the minerals or elements present in it
16. the amount of open space between an object
17. the process of wearing something down by friction

1. layer of rock beneath the soil
2. the expansion of desert conditions in an area where the natural plant cover has been destroyed
3. the process by which rainwater dissolves and carries away minerals and nutrients in topsoil
6. the process in which layers or sheets of rock gradually break off
12. the process in which sediment is picked up and moved from one place to another
13. the process in which transported sediment is laid down
18. horizon a soil layer with physical and chemical properties that differ from those of the soil layers above or below it