1. Earths History: Geological Time, Rocks, Fossils

2. Bell Work My Planet Diary Turn to page 310 in textbook Read article
Answer Questions 1 & 2

3. Geological Time Scale
Timeline that organizes the events in Earths history.
Earth is about 4.7 billion years old.
More complex organism such as land plants and fish evolved only with in the last 500 million years.

4. Humans Humans evolved only about 110, 000 years ago
If humans were squeezed into a single day, humans would not evolve until he last few seconds.

5. Humans Brain Pop
r/humanevolution/

6. Calendar of Earth
The geological time scale is like a calendar extending from earths formation to the present.
The scale is divided into eons, eras, periods, and epochs.

7. Eon
The largest group: divided by the Cambrian boundary (about 550 million years ago) when the variety of life forms explodes: billions of years long

8. Era Mass extinctions mark the boundaries between the eras
hundreds of millions of years long

9. Period Blocks of time when a unique rock series was laid down
tens of millions of years long

10. Epoch
Divisions of the most recent periods
Several millions years long

11. Geological Time Brain pop
gictime/

12. Determining the Age of Rocks
Scientists use rocks and fossils to try to date events, or determine when in history events took place on earth.
Scientists use 3 techniques of dating:
Absolute age
Radioactive dating
Relative age

13. Absolute Age
Tells the actual age of rock or fossil or how long ago an event occurred

14. Radioactive Dating
Is means of measuring the age of a material by comparing the amount of radioactive form of an element in a rock or fossil with the amount of its decay product.

15. How is Radioactive Dating Done??
Scientists FIRST determine the amount of radioactive element in a rock
THEN, scientists compare this amount with the amount of the stable element

16. Let’s Practice! Pennies Lab! REPEAT Steps 1-4 three times
1. Place pennies in a cup
2. Shake cup
3. Dump pennies out
4. Remove the pennies that come up heads
REPEAT Steps 1-4 three times

17. Relative Age
When absolute age is not possible scientists use relative age.
Relative age describes the age of an object or event in comparison to another object or event.
It determines which events occurred earlier or later then others without giving a definite date.

18. Carbon Dating Brain pop
gictime/

19. Law of Superposition
States that in undisturbed sedimentary rock layers, older layers of rock lie beneath younger rock layers
Older sediments must be laid down first before the younger ones pile on top.

20. Other than layers…
Scientists have other clues buried in the rocks other than the layers

21. Extrusions Magma is the molten material BENEATH the earth’s surface
Lava is the molten material that flows to the earth’s surface
Extrusion: lava that hardens on the surface and forms igneous rocks
An extrusion is YOUNGER than the rock beneath it

22. Intrusion
The magnum may push into bodies of rock above its layer but still beneath the earth’s surface
This is called an intrusion
The intrusion is always YOUNGER than the rock layers around and beneath it

23. Unconformity
Plate movements can disturb rock layers by folding or turning them.
Sometimes a layer can be missing one area of rock bed.
The missing layer is called an unconformity.
Makes it more difficult to understand how earth changed at a specific time.

24. Fossils Provides Clues to Earths Past
Fossils can be used to determine the geological history, or age, of the rock that contains them
Younger fossils may be found where the original boundary was an ocean/continent
Older fossils are found in where plates collided, formed mountains, and now eroding.

25. Index Fossil fossil must be widely distributed
represent a type of organism that existed only briefly.
useful because they tell the relative ages of the rock layers in which they occur.

26. Extinction Process which species disappear Occur naturally over time
Most occur following a sudden, drastic change in the environment.
Species cannot adapt quickly enough to survive

27. Through Out History
Throughout history numerous species of organism have gone extinct
Some scientists estimate that 99.9% of all species have ever lived on earth is extinct
Average species lives for 2 to 10 million years

28. Extinction Increase in temp Increase or decrease in rainfall
Volcanic eruption
Flooding or drought
Shifting land or sea
A change in food supply
A new predator or disease

29. Mass Extinctions
Occurs when large numbers of species die out in a short amount of time.
Mass extinctions have occurred many times in Earths history
Each event has wiped out more then 50% of species
Have evidence in rock layers.
Abundant fossils suddenly disappear.

30. Extinction
Brain Pop
ment/extinction/

31. Finding Clues to Rock Layers
Pg 330
Procedure
1 make a venn diagram
2 make a list
Analyze and Conclude
1-8 answer in complete sentences
Turn in procedure and analyze and conclude