Those layers are classified as this substance's namesake horizons, which together produce this substance's namesake profile.
This material is classified into namesake orders that include histosols and aridisols. The first three layers of this substance are labeled O, A, and B, respectively. Those layers are classified as this substance's namesake horizons, which together produce this substance's namesake profile. Most of this material on Earth is younger than the Pleistocene epoch, and cellulose is the most abundant plant residue in this material. Five percent of this material's volume is composed of humus. For 10 points, name this material, comprising the first few feet of the crust, that contains the root systems of plants as well as nutrients needed to support them.
This material is classified into namesake orders that include histosols and aridisols.
soil [or topsoil]