Soil • Soil is made of • A. weathered rock/

sediments• B. humus- decayed

plant and animal matter

• C- living organisms- (worms, fungi and insects)

Soil Horizons- layers of the soil

• A horizon- also called topsoil is made up of dead and decaying plants and animals. This layer is dark in

color and rich in nutrients that are used by plants. • B horizon- this layer is lighter in color because

there is not any humus. Minerals are washed downward from the A horizon into this layer by a process called leaching.

• C horizon – this layer is the parent material containing mostly weathered rock or sediment

Soil profiles -side view of the different horizons (layers ) of soil in the

ground.

Factors that affect soil formation

• Parent material-

• Type of vegetation- see next slide

• Slope of the land

• Climate

• Time

Notice the thicker darker top layer at the bottom of the slope