1. Geologist interpret Earth’s history by studying sedimentary rocks Relative Dating

2. Interpreting Earth’s History 1.Rock record gives evidence of geological event (earthquakes, volcanoes, erosion) and life forms of the past (dinosaurs) 2. Processes we find on Earth today also worked in the past 3. Earth is very old and changes over geologic time

3. Uniformitarianism Physical Laws Chemical Laws Biological Laws

4. Steno’s Laws  Law of superposition (each layer is older than the one above it)  Principle of Original Horizontality (layers of sediment are deposited in a horizontal position  Principle of Cross-Cutting Relationships (a fault cuts through rock or magma intrudes then the fault or intrusion is younger than the rock it cuts through)

5. Law of Superposition

6. Principle of Original Horizontality

7. Principle of Cross-Cutting Relationships