Why is the ninth month called September?
1610s, from Modern Latin stratificationem (nominative stratificatio), noun of action from past participle stem of stratificare "to form strata," from stratum "thing spread out" + root of facere "to make" (see factitious).
stratification strat·i·fi·ca·tion (strāt'ə-fĭ-kā'shən)
An arrangement in layers or strata.
The process by which materials form or are deposited in layers, as in sedimentary rocks and some igneous rocks.
Note: The atmosphere and the ocean also exhibit stratification, with the warmer air or water occupying the upper layers.