1. Earth History

2. Earth history Vocab
Sedimentary rock layers - formed by the accumulation of sediments (sand, silt, clay)
Rock layers provide a history of how life forms have changed over time

3. Earth history vocab What is a fossil?
Fossils – evidence of former life on earth
What conditions do they form under?
Low oxygen levels, fast burial, low heat
Provide proof of how life and environmental conditions have
changed

4. Earth history vocab Lithospheric plates
regions of Earth's crust that are divided into plates that move across the surface of the earth

5. SAMPLE LIFE TIMELINE 1988 – Birth, at the hospital
1991 – little sister is born
1993 – started school (kindergarten)
1999 – my cousin came to live with us
2001 – my cousin moved out
2002 – graduated from 8th grade

6. Interrupting fossil layering
Folding of rock layers
due to compression
Uplift occurs when areas of the crust move up due to tectonic plate movements
Folding video if time

7. Index Fossils Used to define periods of geologic time Should be…
distinctive, widespread, abundant
Limited in geologic time

8. Relative Dating Uses rock layers and fossils to determine age of rocks
Example:
Law of Superposition - undisturbed sedimentary rock layers are in age order
A and B activity

9. How to use relative dating
Fauna A
1 Rapidly spread
2 Dies out quickly
3 Valuable Index Fossil
Fauna B
1 Spreads slowly
2 Does not die out quickly
3Poor Index Fossil

10. Relative dating practice

11. Absolute dating
Allows scientists to date a rock to a specific year or range of years
Example :
Carbon 14 (radiocarbon) dating
Uses the amount of C 14 in a dead organism to estimate how old it is

12. Is rock layer "A" younger or older than the other rocks
Is rock layer "A" younger or older than the other rocks? What evidence explains your answer?
Is the fault (dotted line labeled "L") older or younger than layer D? Explain your answer.
List the rock layers in order from oldest to youngest. (include the lines "K and L").
E, f, g, h, I, j, l, k, d, c, b, a

13. Radioactive dating Is a form of absolute dating
Calculating age by measuring the amount of radioactive material a substance contains
Radioactive material – unstable elements that break down over time
Ex : Uranium

14. Uranium Is radioactive Cannot be altered by temperature or pressure
The rate at which it breaks down (decays) is constant
Cannot be altered by temperature or pressure
Using uranium, scientists have dated the earth to be 4-5 billion years old

15. Radioactive Dating Practice
If 100 grams of pure carbon-14 starts to decay, how many grams of carbon-14 (N-14) will be left after 11,400 years?

17. Rock Cycle 3 main types of rock
All rocks on earth were once igneous rocks
Igneous rocks - form as liquid magma cools
Intrusive igneous- cooled below the surface
Extrusive igneous- cooled on the surface
Extrusive igneous rock

18. Rock Cycle
Sedimentary rocks – form from deposits of sediment on the earth’s surface ( usually in aquatic environments)
Metamorphic rocks - form deep in the Earth when heat and pressure are applied to igneous or sedimentary rocks

19. Rock Cycle Questions How was it formed/made?
Was it “birthed” in hot or cold conditions?
Would you expect it to have layers?
Are you likely to find fossils in it? Why?
What can it turn into next?
Memory trick / picture
Question
Number
Igneous
Metamorphic
Sedimentary 1
From cooling magma either inside or above the earth
From heat and pressure applied to sed or igneous rock 2

20. Identifying rock layers
How can we identify a rock layer?
By minerals – color, hardness, metallic or not
By temperature – affects size of crystals
By how much pressure made it - density of rocks

21. Rock id challenge
Contains numerous bubble-like cavities that may or may not be lined with minerals, Has obvious bubbly or frothy texture, Is fine-grained, uniform in texture, glassy, Made of discrete mineral grains locked together (may be loosened by weathering)
Has obvious stratification, Very soft (easily scratched by a knife), Obviously made of particles cemented together, Contains fossils
Has a fine texture with an obvious directional grain (foliation) Has obvious bands, streaks or clumps of different minerals Is made mostly of quartz or calcite but is coarse-grained and lacks sedimentary features, May often have features of original rock but is recrystallized or chemically changed

22. ICE CORE VIDEO QUESTIONS
Ice cores provide a high resolution record of hemispheric and ___________ scale climate change.
The ice is taken from the _______ of the core so it is not contaminated.
Ice cores tell us about the ancient _______________ of Antarctica.

23. A storm with high winds moves over a large lake
A storm with high winds moves over a large lake. What effect does this have on the lake’s water quality?
A It decreases the turbidity of the water.
B It increases dissolved oxygen levels.
C It decreases the acidity of the water.
D It increases the pH of the water.

24. Which energy resource does not ultimately rely on the Sun?
A solar cells
B biomass
C wind
D geothermal