Geol. a basic law of geochronology, stating that in any undisturbed sequence of rocks deposited in layers, the youngest layer is on top and the oldest on bottom, each layer being younger than the one beneath it and older than the one above it.
LAW OF SUPERPOSITION
Meaning of LAW OF SUPERPOSITION in English
Random House Webster's Unabridged English dictionary. Полный английский словарь Вебстер - Random House . 2012