1. Mountaintop Fossil?
The Esposito family was hiking on a mountain and found a shell fossil. They had different ideas about how it got there. Decide with whom you agree and explain:
Mom: A bird picked up the organism and dropped it on the mountain top.
Dad: Water, ice, or wind carried the fossil to the mountain top.
Rosa: The mountain formed in an area that was once covered by ocean.
Bill: The fossil flowed out of a volcano that rose up from the ocean floor.

2. The Rock and Fossil Record
History of the Earth
Uniformitarianism:
Hutton (1795)
Earth changes in the same way over long periods
Past is key to future

4. What would the discovery of marine fossils on the top of Canadian mountains mean?

5. Catastrophism
Believed earth only few thousands of years
Changes happened quickly by catastrophes

6. What other types of catastrophes may happen on Earth?

7. Modern Geology Compromise
neither uniformitarianism nor catastrophism accounts for all geologic change
most geologic change is gradual and uniform, catastrophes have occurred

8. Relative dating
The bottom layers of rock are usually the oldest layers. The top layers are usually the youngest layers.
Scientists can use the order of these rock layers to determine the relative age of objects within the layers.
Estimating the age of rock layers in this way is called relative dating.
For example, fossils in the bot- tom layers are usually older than fossils in the top layers

9. Geologic Column
Made by piecing together undisturbed rock columns from around the world (p.131)

10. Absolute Dating
Measures the age of fossils or rocks in years by examining atoms.
When an atom decays, it becomes a different and more stable kind of atom. Each kind of unstable atom decays at its own rate. the time that it takes for half of the unstable atoms in a sample to decay is the half-life
By measuring the ratio of unstable atoms to stable atoms, scientists can determine the approximate age of a sample of rock.
uranium-238 has a half-life of 4.5 billion years. scientists can use the decay of uranium-238 to date rocks or fossils that are millions of years old
carbon-14 has a half-life of only 5,780 years. Scientists use carbon-14 to date fossils and other objects that are less than 50,000 years old

11. Naturally preserved evidence of life Most found in sedimentary rock!
Fossils
Naturally preserved evidence of life
Most found in sedimentary rock!
----- Meeting Notes (9/30/13 11:17) -----
Number 18 on the study guide!!!

12. Fossils in Rock

13. Dinosaur Head

14. Bird Fossil in Rock

15. Tooth

16. Amber Fossils
Hardened tree sap.

17. Frozen Fossils Wooly Mammoths Prehistoric man Asphalt Fossils:
Trapped in sticky pools of tar
Saber toothed tigers, snails, plants, etc.
LaBrea Tar Pit, CA

18. Marine Fossils: Help scientists reconstruct ancient coastlines and shows the deepening and shallowing of ancient seas. Ex. Finding a marine fossil on top of a mountain

19. Trace Fossils
Preserved evidence of animal’s activity
Foot prints preserved in rock.

20. Molds and Casts
Mold: cavity left when organism has decayed
Cast: filled in mold and becomes rock
Show changes in past environments and organisms

21. Index Fossils Found throughout world
Lived for very short, well-defined period of time.
Trilobites: found in rock layers 400 million years old

22. Geologic Time Scale
Represents 4.5 billion years divided into distinct intervals
Divisions:
Eons ( largest divisions)
Eras (contains 2 or more periods)
Periods (longer than epoch, but shorter than era)
Epochs (longer than an age, but shorter than a period)

24. Paleozoic Era
Old life
mya
From no land organisms to amphibians, plants, & insects
Ended by largest mass extinction of Earth’s history
Ocean changes – 90% died

25. Mesozoic Era
“Middle Life”
mya
Age of Reptiles (dinosaurs)
Small birds & mammals toward end
Global climate change ended

26. Cenozoic Era
Recent life
65 million yrs ago to now
Age of Mammals
Some extinct: mammoths, saber-toothed, giant sloths