1. Soil part of the regolith that supports the growth of plants.
Regolith: layer of rock and mineral fragments that covers Earth’s land surface. 1

2. How is Soil Formed?
By rock being eroded away. 2

3. Characteristics of Soil
Soil Composition
Soil has four major components
A. Mineral matter (broken-down rock)
B. Humus (decayed remains of organisms)
C. Water
D. Air 3

4. Characteristics of Soil
Texture refers to the proportions of different particle sizes.
A. Sand (large size)
B. Silt – feels like flour
C. Clay (small size)
D. Loam (a mixture of all three sizes) is best suited for plant life. 4

5. Characteristics of Soil5

6. Time, Climate, Organisms and Slope
The longer a soil has been forming, the thicker it becomes.
Climate
Greatest effect on soil formation
Organisms
Furnish organic matter to soil
Slope
Steep slopes often have poorly developed soils. 6

7. Soil Types Location Contents Pedalfer Pedocal Laterite
under forest vegetation
iron oxides and aluminum-rich clays in the B horizon
Pedocal
drier grasslands
Calcium carbonate
Laterite
Hot, wet, tropical climates
Intense chemical weathering to the top layers of soil 7