stratify

strat·i·fy

1. To form, arrange, or deposit in layers.
2. To preserve (seeds) by placing them between layers of moist sand or similar material.
3. a. To arrange or separate into castes, classes, or social levels.
   b. To separate into a sequence of graded status levels.

1. To become layered; form strata.
2. To develop different levels of caste, class, privilege, or status.