stratify

divide society into social classes or castes; "Income distribution often stratifies a society"

form layers or strata; "The rock stratifies"

develop different social levels, classes, or castes; "Society stratifies when the income gap widens"

form, arrange, or deposit in layers; "The fish are stratified in barrels"; "The rock was stratified by the force of the water"; "A statistician stratifies the list of names according to the addresses"

render fertile and preserve by placing between layers of earth or sand; "stratify seeds"