stratify

stratify
    v 1: divide society into social classes or castes; "Income
         distribution often stratifies a society"
    2: form layers or strata; "The rock stratifies"
    3: develop different social levels, classes, or castes; "Society
       stratifies when the income gap widens"
    4: 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"
    5: render fertile and preserve by placing between layers of
       earth or sand; "stratify seeds"
    

Stratify \Strat"i*fy\, v. t. [imp. & p. p. {Stratified}; p. pr.
   & vb. n. {Stratifying}.] [Stratum + -fy: cf. F. stratifier.]
   To form or deposit in strata, or layers, as substances in the
   earth; to arrange in strata.
   [1913 Webster] Stratigraphic