Impacts 1

Question 1

List the major subdivisions of the geological time scale

Answer 1

Paleogene - 65 Ma
Cretaceous
Triassic - 251 Ma
Permian
Devonian
Ordovician
Cambrian - 543 Ma

Question 2

Relative time scale between the two eons

Answer 2

Precambrian - 4.5 Ga
Phanerozoic - 543 Ma

Question 3

Describe the concept of a biosphere within the Earth System

Answer 3

• Biosphere is parts of earth where life exists
• allowed us to reconstruct components of the past thanks to fossils

Question 4

Explain how the Biosphere has evolved over time

Question 5

What are the four principles of stratigraphy?

Answer 5

1. Law of Superposition
   - rocks on top are younger
2. Principle of Original Horizontality
   - even if strata are tilted today, they were originally flat
3. Principle of Lateral Continuity
   - layers of rock can often be traced out laterally ex/ Grand Canyon
4. Principle of Cross-Cutting Relationships
   - a rock cutting through another must be younger

Question 6

What is faunal succession?

Answer 6

The change of fossils over time, because of evolution.

-> this makes biostratigraphy possible

Question 7

What are ideal fossils in biostratigraphy? Name the four criteria.

Answer 7

Index fossils

1. common
2. wide geographical distribution
3. short fossil range (amount of time a species existed for)
4. died in good preservation envo (i.e. not in the deep waters)

Question 8

Name the historical figures in the development of stratigraphy and biostratigraphy

Answer 8

1. Nicholas Steno
2. Giovanni Arduino
3. James Hutton
4. George Cuvier
5. William Smith

Question 9

What are the five mass extinctions?

Answer 9

End Cretaceous - 66 Ma
End Triassic - 200 Ma
End Permian - 250 Ma
Late Devonian - 360 Ma
Late Ordovician - 450 Ma

Question 9

How old is the Earth?

Answer 9

4.5 billion years

Question 10

What makes up 87% of Earth’s history?

Answer 10

Precambrian

Question 11

What was the Cambrian Explosion?

Answer 11

• huge flourish of animals and plants that left fossils
• no evidence of life prior to this
• first life was the prokaryotes

Question 12

What is stratigraphy and the different types?

Answer 12

The study of layers of rock by …

• chrono = time
• litho = rock type
• bio = fossils
• chemo = chemistry

Question 13

1. Nicholas Steno

Answer 13

deeper layers of rock are older

Question 14

2. Giovanni Arduino

Answer 14

started naming layers of rock in the Alps based on depth and composition

Question 15

3. James Hutton

Answer 15

proposed uniformitarianism

• “the present is the key to the past”
• The natural processes that operate today have always operated in the past

Question 16

Fossils can be used to define _______

Answer 16

Stratigraphic biozones

• two rocks with similar fossil species are likely deposited at similar time
• Biozones can be used to correlate rocks of similar age
• idea was proposed before Darwin’s evolution theory

Question 17

4. George Cuvier

Answer 17

Fossils were once living organisms that can become extinct

Question 18

5. William Smith

Answer 18

fossils can be used to organize the age of rocks everywhere

-> same fossils = same time deposited, even if at a different place

Question 19

A huge amount of time was organized using ____. This was only possible because _____

Answer 19

fossils
species have evolved

Question 20

What are unconformities?

Answer 20

period of active erosion or movement that disrupts stratigraphy

Question 21

The first unconformity

Answer 21

Siccar Point, Scotland
discovered by James Hutton in 1788

Question 22

Faulting

Answer 22

layers of rocks disrupted/offset by earthquakes

Question 23

Example of Index Fossils

Answer 23

Ammonites
(251-66 Ma = during the age of the dinosaurs)

Question 24

What happens after a mass extinction?

Answer 24

Adaptive radiation - rapid diversification of life into new forms and species - new ecological niches. envos, resources, etc

Question 25

What marks some of the key boundaries between geological time periods?

Answer 25

Mass extinctions

Question 26

Rate of background and mass extinctions

Answer 26

5-10% of species per million years ex/ the last ice age greater than 30% of species per million years

Question 27

Sixth Major Extinction

Answer 27

due to appearance of humans - 1% of mammals extinct in just 300 years - current extinction rate is 30k times faster than background rate

Question 28

What scale do we use to organize Earth's history?

Answer 28

Geological Timescale

Question 29

Difference btwn stratigraphy and biostratigraphy

Answer 29

- stratigraphy is the study and organization of layers of rocks - biostratigraphy is an important part of stratigraphy -> fossils are useful for correlating strata and placing them in age order

Question 30

what are strata

Answer 30

layers of rocks