Relative and Absolute Dating Principles in Geology

What is the principle of Superposition?

In undisturbed sedimentary rock layers, the oldest layers are at the bottom and the youngest at the top.

What does the principle of Original Horizontality state?

Sediment is deposited in horizontal layers.

What is the principle of Lateral Continuity?

Layers of sediment extend laterally in all directions until they thin out or pinch off.

What are Cross-Cutting Relationships?

A fault or igneous intrusion is younger than the rock it cuts through.

What is the difference between relative and absolute dating?

Relative dating places events in relation to each other, while absolute dating determines the exact age of events.

What is the order of rock layers, intrusion, and fault from oldest to youngest?

C, A, B, D, E

What are index fossils?

Remains of organisms that lived during a specific time and can help determine the age of rock layers.

How are index fossils formed?

They are formed from the remains of organisms that died within a particular time frame.

What are two limitations of using C-14 dating?

1. C-14 is radioactive. 2. It is only effective for dating up to about 70,000 years.

What is half-life?

The time it takes for half of the radioactive atoms in a sample to decay.

What is the relationship between parent and daughter isotopes?

As the parent isotope decays, the amount of daughter isotope increases over time.

How is half-life used for absolute dating?

Scientists compare the ratio of parent to daughter isotopes and use the known half-life to calculate the rocks' exact age.