... frequently they snap due to tension pulling the rocks apart One side of the fault drops relative to the other—or is pushed up by pressure—and the rock strata become offset By matching the layers, ... layers lie at the bottom, so if they are compressed into rock, the oldest rock layers, or strata, are also the lowest However, movements in the Earth can fold and even overturn the strata, so ... rock without being disturbed, they become horizontal strata The lowest strata are the oldest All these rocks date from the Cretaceous period of the age of dinosaurs The older brown and red strata...