Soil

1. is made of

1.1. made of

1.1.1. definition

1.1.1.1. nutrients

2. Descriptions

3. Soil types

3.1. sand

3.2. silt

3.3. clay

4. layers

4.1. organic

4.1.1. top soil

4.1.1.1. subsoil

4.1.1.1.1. parent material

5. weathered rocks

5.1. sand

5.1.1. silt

5.1.1.1. clay