1. Weathering and Soil Formation
Chapter 10
Weathering and Soil Formation

2. Chap 10, Sec 3 (From Bedrock to Soil)
Objectives:
Describe the source of soil.
Of what is soil made?
What are the layers in the soil profile and what is their function?

3. Tech Terms:
soil – a loose mixture of geologic (inorganic material - rocks) and biologic (organic material – dead animals) that supports the growth of plants.
**The amount of sand, silt, and clay, determine a soil’s texture!!!**

6. (Copy the particles & sizes here from Fig 2 on pg. 289)

7. 2. soil horizons – layers of soil that differ in color and texture from the layers above and below.

8. *Because soils are made from weathered rock fragments, the type of soil that forms depends on the type of rock that weathers.* (For example: Granite of Stone Mountain vs. Limestone of Hilton Head Island)!
CAN YOU THINK OF OTHERS?

10. O horizon (litter) – organic, slightly decomposed material from fallen leaves, plants, and animals.
A horizon (topsoil) – near surface, and contains the MOST humus of any layer (nutrient rich)
E horizon – zone of eluviation and leaching (downward movement of dissolved material)

11. B horizon (subsoil)- contains little or
no humus.
C horizon (weathered parent material) - contains only weathered rocks and minerals that come from the bedrock layer beneath.
R horizon - bedrock

12. Soil Horizons WS:
O – This is the top layer, the “organic” layer which is made up of dead plant matter for the most part.
A – This is the second layer of soil, what we call the “top soil”. It too has lots of organic matter mixed in and is usually darkly colored.
B – Subsoil layer. There isn't much organic stuff in here. Sometimes the transition between top soil and subsoil is very sharp and defined and sometimes they fade into one another.
C – This layer usually has lots of large rocks mixed in with soil deep underground.
D – This is the bedrock that lies beneath the soil. In some places this can be quite near the surface and in others it is very, very deep.

13. soil fertility – the ability of soil to hold and supply nutrients to a plant.
humus – dark, organic material formed in soil from the decayed remains of plants and animals.

14. The example below is of Florida soil
leaching – when water dissolves and carries nutrients in the topsoil through the horizons.
The example below is of Florida soil

15. In Summary: https://www.brainpop.com/science/earthsystem/soil/