Above is a diagram illustrating soil horizons. Describing the horizons from the surface down deeper into the ground:

The first layer or horizon is labeled as O1: Organic-original forms recognized (litter).

The next horizon is labeled as O2: Organic-original forms not recognized (humus).

The next horizon is labeled as A1: Mineral-mixed with humus-dark colored.

The next horizon is labeled as A2: Horizon of maximum eluviation or silicate clays. Iron and aluminum oxides, etc. Light colored.

The next horizon is labeled as B: Maximum eluviation of silicate clays. Iron and aluminum oxides. Some organic matter.

The next horizon is labeled as C: Zone of least weathering. Accumulation of calcium and magnesium carbonates. Cementation.

The last horizon shown is labeled as IIC, which is a layer of bedrock.