Over a 15 year period, the river has been cleaned up, fish have returned to the river, and the remaining pollutants are being removed. O-horizon is mostly organic matter. A-horizon is topsoil with organic matter. B-horizon or subsoil is clay with leached minerals. C-horizon is weathered bedrock.
Bedrock is parent material.
In wet soil, water fills space between soil particles. In dry soil, air fills pore space, although soil particles are covered by a thin film of water. Biodiversity in rich soil includes plants, algae, fungi, earthworms, flatworms, roundworms, insects, spiders, mites, bacteria, and burrowing animals such as moles, shrews, and groundhogs. Sand particles are larger than silt particles are larger than clay particles. Larger particles give soil structure, support, and aeration while smaller particles bind together into clumps and hold water and minerals.