| A | B |
|---|
| pedogenesis | the soil formation process |
| soil horizon | the horizontal layering formed during pedogenesis |
| soil profile | the vertical sequence of soil horizons |
| solum | the soil horizons known as the "true" soil |
| topsoil | the upper portion of the solum which contains humus |
| subsoil | the lower portion of the solum, lacking humus |
| humus | decayed and weathered plant debris |
| parent material | the D-horizon, the presursor material of a soil profile |
| D-horizon | a soil profile's parent material |
| C-horizon | partially weathered parent material |
| B-horizon | the soil horizon gaining mineral material |
| hardpan | well-formed B-horizon that gains clay minerals |
| caliche | a well developed B-horizon that gains calcite |
| E-horizon | a soil horizon that loses minerals by eluviation |
| A-horizon | a soil horizon that loses minerals by chemical leaching |
| O-horizon | uppermost soil horizon that has gains organic material |
| litter | decaying/weathering plant debris found in a forest |
| thatch | decaying/weathering plant debris found in a grassland |
| pedocal | soil type where calcite is found in the B-horizon |
| pedalfer | soil type in which clays are found in the B-horizon |
| laterite | soil type in whcih oxides are found in the B-horizon |
