Earth History

Question 1

Metamorphic Rock

Answer 1

crystal structure is altered by extreme heat + high pressure when buried deep in the Earth’s crust
- may be formed from either igneous or sedimentary rock
- fossils contained in sedimentary rocks are destroyed during the transformation to metamorphic rock

Question 1

Igneous Rock

Answer 1

rock formed from cooling of lava - any organismal remnants are destroyed by the extreme heat of the lava

Question 2

Sedimentary Rock

Answer 2

rock formed by deposition of fine sand and particles of organic and inorganic debris at the bottoms of oceans and lakes
- compressed and often visible as layered rock formations
- fossils are found in sedimentary rocks

Question 3

Stratigraphy

Answer 3

study of rock layers, usually comprised of sedimentary and layered volcanic rocks
- studying the makeup of the Earth’s crust

Check images from Earth History page of notebook of unique features!

Question 4

Uplifts / Crystal Movements

Answer 4

may cause layers to tilt, fold, or become inverted

Question 5

Unconformities

Answer 5

erosion can cause loss of layers and gaps in the rock records

Question 6

Radiometric Dating

Answer 6

• stratigraphy reveals the order of geological events, but NOT their absolute dates
• radioisotope decay methods can be used to find the age of rocks in different layers

Question 7

Half-Life

Answer 7

time required for half the radioisotope initially present to undergo decay

Question 8

Potassium- 40

Answer 8

• decays to Ar-40
• 1.26 billion year half life
• used to date formation of igneous rocks

Question 9

Uranium-238

Answer 9

• decays to Pb-206
• 4.5 billion year half life
• used to date planets

Question 10

Carbon-14

Answer 10

• decays to N-14
• 5715 year half life
• used to date organic matter, but not useful in dating fossils
• not good to date rocks from billions of years ago since the half life is so small

Question 11

KEY MILESTONES

Answer 11

1. Hadean Eon
2. 1st evidence of life
3. Great Oxygenation Event
4. Cambrian Explosion
5. Permian Extinction
6. Dinosaurs die
7. Lucy fossil found
8. Recorded history begins

Question 12

Earth’s Crust

Answer 12

• the oldest rock is on the bottom and gets younger as you reach the surface
• the crust is thin and has flowing magma under it
• folding can occur
• NOTICE fault lines/magma channels: if it cuts through something, then that thing was there before the cuts occurred

Question 13

Evidence: Hadean Eon

Answer 13

• radiometric dating
• the moon

Question 14

Evidence: 1st Evidence of Life

Answer 14

stromatolites

Question 15

Evidence: Great Oxygenation Event

Answer 15

CAUSED BY CYNOBACTERIA PHOTOSYNTHESIS
- banded iron formations (iron precipitating out of water due to high O2)
- fossils

Question 16

Evidence: Cambrian Explosion

Answer 16

HAPPENED IN THE OCEAN, CAUSED BY OXYGEN IN THE ATMOSPHERE
- fossil evidence

Question 17

Evidence: Permian Extinction

Answer 17

WORST MASS EXTINCTION
- volcanic ash
- fossils
- changes in % of certain elements

Question 18

Evidence: Dinosaurs dying

Answer 18

• fossil evidence

Question 19

Adaptive Radiation

Answer 19

a period of rapid speciation and increasing biodiversity
- occur when new niches develop (EX: niches open up after extinctions)
- evolutionary innovation (EX: jaws, eyes)

Question 20

Mass Extinction

Answer 20

massive loss of species in a short time frame
- there have been 5 (caused abiotically)
- loss of biodiversity –> more niches!