1. SSA Review 4 – Earth’s History

2. How do we know how old the Earth is?

3. Law of Superposition – in undisturbed horizontal sedimentary rock layers the oldest layer is at the bottom. Each higher layer is younger than the layer below it.

4. Which layer is the oldest?

5. Radioactive Dating – measures the amount of decay (HALF LIFES) of radioactive elements in a rock. The more decay, the older the rock.

6. The oldest rock formation identified on Earth is found on the shoreline of Hudson Bay in Canada. This rock formed approximately 4.28 billion years ago. Which information does a scientist need to most accurately determine the age of a rock?
A. The percentage of each mineral that makes up
a rock
B. The thickness of younger rock layers that cover
the rock
C. The amount of radioactive element that is
present in the rock
D. The amount of weathering that has occurred on
the surface of the rock.

7. Uniformitarianism:
*The geologic processes that are happening today also happened in the past.
Weathering
Erosion
Plate tectonics

8. The Rock Cycle
*What are the methods that rocks are broken down and moved through the rock cycle?

10. Igneous Rocks

12. Sedimentary Rocks

14. Metamorphic Rocks

16. Weathering & Erosion Weathering – the process of breaking
down earth’s rocks by
wind, water, ice, plants,
or other physical means *Sediments
Erosion – the process of wind, water, or ice moving sediments from one place to another