subsoil

noun subsoil

• alluvia — a deposit of sand, mud, etc., formed by flowing water.
• alluvium — a fine-grained fertile soil consisting of mud, silt, and sand deposited by flowing water on flood plains, in river beds, and in estuaries
• earth — (often initial capital letter) the planet third in order from the sun, having an equatorial diameter of 7926 miles (12,755 km) and a polar diameter of 7900 miles (12,714 km), a mean distance from the sun of 92.9 million miles (149.6 million km), and a period of revolution of 365.26 days, and having one satellite.
• glebe — Also called glebe land. Chiefly British. the cultivable land owned by a parish church or ecclesiastical benefice.
• humus — the dark organic material in soils, produced by the decomposition of vegetable or animal matter and essential to the fertility of the earth.