O Horizon
The top layer, mostly composed of organic matter such as decomposing leaves; thin in some soils, thick in others, and not present at all in others
A Horizon (Topsoil)
Mostly minerals from parent material with organic matter incorporated; a good material for plants and other organisms to live
E Horizon
Leached of clay, minerals, and organic matter, leaving a concentration of sand and silt particles of quartz or other resistant materials; missing in some soils, but often found in older soils and forest soils
B Horizon
Rich in minerals that leached (moved down) from the A or E horizons and accumulated here
C Horizon
The deposit at Earth’s surface from which the soil developed
R Horizon (Bedrock)
A mass of rock (such as granite, basalt, quartzite, limestone, or sandstone) that forms the parent material for some soils