1. Soil Formation
6.E.2.3 Explain how the formation of soil is related to the parent rock type and the environment in which it develops.

2. What is soil?
A loose mixture of weathered rock, organic material, air and water

3. Soil Texture This refers to the size of the particles:
Sand (The largest particle size)
Silt
Clay (The smallest particle size)
Loam is a mixture of sand, silt, and clay and is ideal for growing things because the sand lets things flow through the soil and clay hold the water in

4. Nutrients in the Soil
Humus is rich decayed organic material in the topsoil that provides nutrients to plants

5. Factors that Form Soil CLimate Organisms Relief/Topography
Parent Material
Time
These factors affect the processes which affect the soil formation

6. Climate
The weathering rates are greatly affected by rainfall and temperature.
Higher rainfall - increased weathering
Higher temperature - increased weathering
Tropical rainforest have highest rate of energy (nutrients in the soil) and dessert has the lowest

7. Organisms
Organisms work to mix the soil physically by moving soil but also by adding or depleting nutrients
Legumes add nitrates to soil
Plants and trees drop their seeds and leaves into the soil

8. Relief or Topography Erosion and water availability
Erosion can cause A and B to be thinned where there is much erosion
Near rivers and streams, the layers will be thicker

9. Parent Material
The soil is formed, in part, by the weathered rock in the area.
Sandstone - creates sand
Shale - creates clay
Basalt (extrusive igneous rock)- weathers easily
Granite (intrusive igneous rock) - resists weathering

10. Time As soils mature, they will take on more developed horizons.
E horizon can be formed as nutrients from A are leached through the soil
As sediments from a stream are deposited, thicker layers can be formed at the delta

11. Soil Formation Video - Part 1

12. Soil Formation - Additions to Soil
These things can be added to the soil horizon:
Precipitation
Organic Matter (plants and animals)
Salts and other chemicals

13. Soil Formation - Losses in Soil
The soil can have nutrients taken from it:
Chemical and nutrient leaching
Erosion (top or bottom layers)
This can be natural or caused by human use of soil

14. Soil Formation - Translocation
Transportation of materials from one part of the profile to another
Caused by water of animals moving things within the layers of soil

15. Soil Formation - Transformation
The breaking down of rock into sediment and eventually creating soil
Physical and chemical weathering
Clay formation
Organic matter/humus

16. Steps of Soil Formation
Step 1: The bedrock forms and this is the bottom layer of soil which is also known as the R horizon
Formed by the original rock in the crust
Much of this is granite

17. Steps of Soil Formation
Step 2: The bedrock is worn down to weathered bedrock forming the C horizon
This is not solid rock but it is also not fine sediment yet

18. Steps of Soil Formation
Step 3: Over time, the weathered rock gets finer creating the first soil horizon
A Topsoil - This is the horizon in which the plants grow
Rich in nutrients and dark

19. Steps of Soil Formation
Step 4: Nutrients wash out of the topsoil and the subsoil forms. This is called B horizon
Light brown color because the nutrients are not as readily available in this layer because the plants have used the nutrients up

20. Steps of Soil Formation
Step 5: Organic material is added on top of the top soil. This is called the litter or O horizon
Leaves from trees
Debris from plants
Decomposing insects and/or animals

22. E Horizon
Not all soil horizons have this layer. This is formed from an intense leaching of nutrients. This would lie between the A and B horizon

23. Soil Formation Video - Part 2

24. Rocks and Soil - Bill Nye