1. Part 3: Soils & Erosion

2. From Previous Classes…
At this point you should have completed:
Title Page
KWL Sheet
Part 1: Task 1 (Earth’s Crust); Task 2 (Pangea);
Part 2: Task 3 (Map of Earthquakes, Volcanoes, Mountains); Task 4 (Types of Mountains); Task 5 (Volcanoes)

3. Earth’s Crust Booklet Part 3
Part 3 will look at soils and erosion; all the following tasks can be completed on LOOSELEAF and WHITE PAPER and placed in your duotang
Task 6: What is soil?
Define the following soil particles (Clay, Silt, Sand, Pebbles, Humus) (page 214)
List from smallest to largest
Draw diagram of 4 layers of soil and label it
Page 210 in textbook may be useful

4. Earth’s Crust Booklet Part 3
Task 7: Causes of Erosion
Done on LOOSELEAF
Using pages in textbook, explain the 5 causes of erosion
Use diagrams to help in your explanation
How are these factors involved in the formation of soil
Suggested Due Date for Part 3: Thursday June 8th

5. Soil
The Earth’s outer crust (lithosphere) is made up of many different layers of rock
Because it is exposed to the atmosphere and environment it is constantly changing and developing
Rocks that have been exposed to weathering break down into smaller piece and eventually form a layer of soil that plants can grow in
Dead and decaying biotic factors (dead animals, plants etc) also contribute to the nutrient level of the soil

6. Soil Layers
As soil develops it creates a series of layers that are called HORIZONS
As you go deeper, the size of rock particles gets larger (less exposure to weathering)

7. Soil Layers Layer 1 (Horizon O): Litter Layer 2 (Horizon A) Topsoil
Surface level; covered with leaves, broken branches, insects and microorganisms keeps ground damp and prevents too much water from evaporating
Layer 2 (Horizon A) Topsoil
Contains dark decaying plant and animal matter (humus), minerals and nutrients, also made of sand and silt
where seeds and plant roots thrive;
Layer 3a (Horizon B): Subsoil
Contains mineral deposits that have settled, larger pieces of rock and clay, lighter color (due to little humus)
Layer 3b (Horizon C): Regolith/Substratum
Rocks and little organic material (roots don’t grow this deep)
Layer 4 (Horizon R): Bedrock
Unbroken rock, still exposed to some weathering

8. Fertile Soil (Horizon O and A)
one of the world’s most valuable resources
In Canada, less than 1% of the total land area is prime agricultural land
Good soil= lots of humus
humus: decaying plant and animal material (gives it dark colour) supplies plants with nutrients to grow; damp and sticky

9. Fertile Soil (Horizon O and A)
Good soil has equal proportions of sand, silt and clay
Sand, silt and clay are different textures due to particles in them
Water and air fill spaces between particles (what plants need)
Sand: large particles/spaces between particles (easy for roots to grow), but drain water quickly
Clay: small particles/spaces between particles; prevent water entering easily, less soil organisms
Silt: in between clay and sand; hold water, but allow roots to grow
Best to have a mix of all 3 types