Picture a cliff that has been cut open. Bands of rock lie one on top of another, each one its own layer, with clean lines between them. Stratification can be thought of as that picture itself: the making of layers, and the pattern of layers you are left with. Wherever the word turns up — rock, a forest, a society, a set of data — the speaker usually has that stack of bands in mind.
可以想成一面被切開的山壁：一條一條的岩層疊在一起，層跟層之間界線很清楚。stratification 就像在說這張圖本身——東西被堆成一層一層，而且看得出來誰在上面、誰在下面。不管講的是石頭、森林、社會還是資料，用到這個字的時候，心裡多半都是這個畫面。
From the word’s history
The word is built from stratum, meaning a layer, plus -ification, the making of something. The word itself says: the making of layers.
這個字是 stratum（一層）加上 -ification（形成…的過程）組起來的。字面意思就是「把東西弄成一層一層」，和上面那張圖剛好對上。
Wiktionary, "stratification"
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