1. What 2 layers make up the topsoil?

2. Horizon O and horizon A make up topsoil.

3. What layer is made up of partly weathered rock?

4. Horizon C is composed of partly weathered rock.

5. How does material move from horizon A to horizon B?

6. The process of leaching moves material from horizon A to horizon B.

7. What do horizon A and horizon B have in common?

8. Both horizon A and horizon B have decayed organic material called humus.

9. Where does the material in horizon C come from?

10. The partly weathered rock in horizon C comes from unweathered parent rock.

11. What is the composition of horizon O?

12. Horizon O is composed of leaf litter and other organic matieral.

13. In what horizon is there very little organic material?

14. Horizon C had very little organic material.

15. What is the composition of horizon R?

16. Horizon R is composed of unweathered parent material.

17. How are horizon A and horizon C different?

18. Horizon A is rich in organic material and horizon C has very little organic mateial.

19. Why do plants grow well in horizon A?

20. Plants grow well in horizon A because it is rich in organic material and nutrients.