A soil profile is an exposure from the surface downward through a soil to its parent material. Soils-3-1 Image: NRCS Image: Martin Miller

Soil profiles generally expose three layers or soil horizons. Soils-3-2 Image: National Cooperative Soil Survey

The upper “A” horizon contains organic matter mixed with mineral particles. Percolating water dissolves and removes some mineral constituents from the “A” horizon. Horizon “A” Soils-3-3

Some constituents dissolved from the “A” horizon are deposited below in the “B” horizon. Horizon “A” Horizon “B” Soils-3-4

The “C” horizon is the lower soil layer developed on the underlying parent material. Horizon “A” Horizon “B” Horizon “C” Soils-3-5

A mature soil profile with well developed A, B, and C horizons takes hundreds to thousands of years to develop. Horizon “A” Horizon “B” Horizon “C” Soils-3-6 Image: NRCS