ESCI 401 Lecture Notes - Lecture 30: Oceanic Crust, Absolute Time And Space, Uniformitarianism

• School: UNH
• Department: Earth Sciences
• Course: ESCI 401
• Professor: Boettcher, Margaret S.

Document Summary

The oldest oceanic crust is about 180-200 million years old. Physical processes that we observe today also operated in the past, at about the same rates. Dating refers to measuring the absolute age (the number of years that have elapsed since a rock was created) Sediments are deposited under the influence of gravity in nearly horizontal beds: the principle of superposition, the principle of original continuity, the principle of cross-cutting relations i. The oldest beds were laid first (they"re on the bottom) and the youngest beds were laid last (they"re on the top) If one geologic feature cross-cuts another, the feature that has been cut must be older than the feature doing the cutting. If an igneous intrusion bakes or metamorphoses the rock it intrudes, the metamorphosed rock must be older. If a layer includes pebbles of another layer, the pebbles must be older than the rock it"s surrounded by.