1. Fossils
Geological Time

2. What is a Fossil?
A fossil is the remains or physical evidence of an organism preserved by geologic processes.

3. Types of fossils Trace Fossils Preserved evidence of animal activity
Examples: Foot prints, burrows, animal dung
What might these fossils tell us about the animals that left them?

4. Types of Fossils
Molds
Casts
Fossil that forms when sediments fill in the cavity left by a decomposed organism.
A cavity in a rock where a plant or animal was buried.

5. Where do we find fossils?
In sedimentary rocks
In Amber
In Asphalt
In Ice/Frozen climates
Fossils can be found all over the world, on every continent.

6. Fossil Formation

7. How do fossils form?
Fossils form when an animal or plant is quickly buried in sediment.
An example is a sandstorm or mudslide that covers the remains of the plant or animal.

8. How do fossils form cont.
Sediment accumulates.
Over time they become Sedimentary rocks
Water infused with minerals seeps into bone and replaces bone with rock-like minerals.
New minerals can replace old minerals
Minerals can recrystallize (change their formula)
The fossil can be petrified and turned to stone!

9. Other routes to fossils
Amber:
Trees create soft, sticky sap
Insects, frogs and lizards can get caught in the sap
The sap hardens-preserving the animal
Cold Temperatures:
The cold slows down decay

10. Other routes to fossils
Asphalt
Asphalt wells up in pools
Crude oil seeps through fissures-lighter elements evaporate
Plants and animals get caught
Ex: La Brea- California

11. The lucky few
The majority of all living things either decompose because they are exposed to the elements or they are consumed by other animals!
Check out the decomposition of this bunny:

12. Why aren’t there more fossils
Decomposition
Weathering and erosion
Magma & Melting
Igneous rocks

13. What do fossils tell us? What the dinosaurs eat
What can this tell us?
What the dinosaurs eat
The size of the animals jaw

14. Index fossils
These are fossils that appear only in certain layers of rock. They help scientists date the rock.
These fossils are organisms that lived only during a short, well-defined timespan.
How can these fossils help scientists?

15. I Can
How can this help you explain why the fossil record is an incomplete record of life on Earth?
How can this help you explain how scientists use fossils?