1. 5.2: Soil
regolith: layer of rock and mineral fragments created from weathering
soil: part of regolith that can support plant life

2. Soil Composition mineral matter (rock pieces) organic matter (humus)
soil is made of four main parts:
mineral matter (rock pieces)
organic matter (humus)
water
air

3. Soil Formation type of soil formed is based upon:
parent material (bedrock)
time
climate
living organisms
slope

4. parent material (bedrock) undergoes weathering to become regolith and soil

5. soil is a mixture of mineral and organic matter without any obvious rock structure
regolith

6. soil horizon: over time, soil layers separate into distinct layers
each horizon (layer) will vary based on climate and parent material

7. A horizon: top layer with organic matter (humus)
usually dark in color due to the humus
also called topsoil
this layer supports plant life

8. B horizon: second layer down with more minerals & clay
lighter in color
also called subsoil
this layer is the lower limit for plant roots

9. C horizon: third layer down made of weathered parent rock
doesn’t really look like soil yet

10. parent rock: bottom layer of solid rock
not yet weathered into regolith and soil

11. soil horizons A B C
parent rock

12. soil profile: all the horizons in one area