1. Fossils, Relative Time and Absolute Time
Studying the Past
Fossils, Relative Time and Absolute Time

2. Paleontology
The study of the forms of life existing in prehistoric or geologic times, as represented by the fossils of plants, animals, and other organisms.

3. What do you know about fossils?

4. Fossils Fossilis is Latin for “dug up”
Fossils are the remains, molds or traces of organisms that died a long time ago
Fossils are usually found in sedimentary rock like sandstone, limestone or shale

5. Fossils
Fossils provide evidence that different organisms lived long ago
Fossil organisms many times do not exist on Earth anymore
They have gone extinct or they have evolved

6. Fossils
As we go through the different types of fossils look for what each type of fossil needs to form.

7. 5 Main Types of Fossils Original Remains Replaced Remains
Molds and Casts
Trace Fossils
Carbonaceous Films

8. Original Remains Very rare Examples Most animals decay or decompose
Frozen woolly mammoths
Insects incased in resin (amber)

9. Replaced Remains Actual remains are replaced with minerals
Many hard parts fossilize this way
Teeth
Bones
Shells

10. Molds and Casts
A replaced remain fossil may dissolve leaving behind a mold
Later minerals may fill in the mold creating a cast of the original organism
Click picture to see cast and mold formation

11. Trace Fossils Coprolites Tracks No actual part of the organism is left
Give information about the location of different organisms
Traces like
Impressions
Bite Marks
Burrows
Feces
Coprolites
Tracks

12. Carbonaceous Films An imprint or thin film is left behind
Not the actual organism
Tissue undergo chemical changes

13. What do fossils need to form?
Sediment
Compaction
Water
Minerals
Organism
TIME!!! Lots of TIME!!!

14. Fossil Concept Map 1. Write in the 5 fossil types 2
Fossil Concept Map 1. Write in the 5 fossil types 2. Write in a few details about each fossil type

15. Dating Past Geologic Events
Relative Dating
Example:
On the way home I stopped for gas
First, I ate dinner
I drove home
Then I went to the store
Absolute Dating
Example
I drove home at 5:35
I stopped for gas at 5:25
I ate dinner at 5:00
I went to the store at 5:15

16. Dating Past Geologic Events
What is the difference between these two dating methods?
Relative Time has no actual times but can be put in order
Absolute Time gives actual times

17. Relative Time
Puts events in a sequence without telling when they actually happened
Does not reveal actual age but age in comparison to other events

18. Relative Dating The evidence is in the rocks
Each layer represents a different place in time
Every layer of rock is another part of the timeline

19. Uniformitarianism “the present is the key to the past”
We can watch how things happen now to understand how they happened before.

20. Uniformitarianism
James Hutton realized these processes did not happen quickly therefore the Earth must be very old.

21. Uniformitarianism
Siccar point in Scotland is where he made the observations
Came up with the idea of DEEP TIME

22. Principles of Relative Dating
The Principle of Superposition
The Principle of Cross-Cutting Relationships
Embedded Fragments

23. The Principle of Superposition
Draw This…
Water 3 2 1

24. The Principle of Superposition
The OLDEST rock is on the bottom and the YOUNGEST is on the top
Rocks are deposited horizontally

25. The Principle of Cross-Cutting Relationships
Draw This…
Water 4 2 1 3

26. The Principle of Cross-Cutting Relationships
An igneous intrusion is YOUNGER than the rock it intrudes
A fault is YOUNGER than the rock it breaks

27. The Principle of Embedded Fragments
Water 4 3 2 1

28. The Principle of Embedded Fragments
Rocks that are embedded in other rocks are OLDER than the rock they are found.

29. Unconformity Gaps in time Surfaces have been eroded away
New rock has been laid on top

30. Unconformity

31. Putting in all together
Rock layer correlation
Matching rock in one area to rocks in another
Match characteristics
Match index fossils
Using fossils to tell what type of environment existed

33. Index Fossils
Fossils that can be used to identify a certain rock layer
Fossils that lived within a certain time can give the rock a relative age. See page 653

34. Fossils
Fossils can also give clues to the type of environment existed.
Is there a lot of coral?
Are there a lot of amphibians?
Are there a lot of deep sea animals?

35. Relative Time Use the present to determine past processes
No actual time is given
Fossils can be used to indicate a general time
3 Principles