Uniformitarianism: the processes that act on the Earth’s surface today are the same as the processes that have acted on the Earth’s surface in the past James Hutton “The present is the key to the past”
age of anything compared to the age of something else doesn’t indicate actual date of occurrence
law of superposition: in undisturbed rock, the older rocks will be at the bottom and the youngest rocks will be at the top
law of cross-cutting relationships:an igneous rock cutting through another rock is younger than the rock it has cut-cross
law of included fragments: pieces of one rock found in another rock must be older than the rock in which they are found
Contorted rock, hard to determine relative age (Copiapo, Chile) unconformity: break in the geologic rock record
nonconformity: when stratified rock rests upon unstratified rock
Noncomformity 1.Granite formed 2. Granite exposed by erosion 3. Beds 1-3 deposited
angular unconformity: boundary between horizontal and tilted layers of rock
Angular Unconformity 1.Beds 1-6 deposited 2. Beds 1-6 tilted 3. Erosion 4. Beds 9,10 deposited
disconformity:boundary between layers of rock that have not been deposited continuously
Disconformity 1.Beds 1,2 deposited 2. Erosion 3. Beds 5, 6, 7 deposited