Class Notes- Unit 4

Question 1

What are the 3 Geological times?

Answer 1

1) Relative Time
2) Absolute Time
3) gEological Time scale

Question 2

What is dating?

Answer 2

the procedures we use to:

i. determine when an event took place, and
ii. determine the sequence of events

Question 3

What is the age of a rock?

Answer 3

the time it was emplaced

Question 4

What is relative geological time?

Answer 4

the sequence of processes that have occurred at location.

Question 5

How can we work out relative geological time?

Answer 5

WE can see this with the naked eye–or work it out with fairly simple geological observations.

Question 6

What are the 5 geological observations we can use to determine relative time?

Answer 6

1. superposition
2. intrusion
3. deformation
4. unconformity
5. fossil correlation

Question 7

What did our understanding of relative time begin with

Answer 7

Nicolaus Steno ~ 1660

Question 8

What is the law of superposition?

Answer 8

younger rock layers are deposited on top of older rock layers (stratigraphic succession)

Question 9

What is stratum?

Answer 9

1 layer

Question 10

What is strata?

Answer 10

several layers

Question 11

What is the principle of original horizontality

Answer 11

Noticed that rock layers were largely horizontal

Question 12

What is intrusion?

Answer 12

intrusions in rock strata (the intrusion is younger than the rock it cuts) from magma…volcano is optional

Question 13

Deposition___erosion

Answer 13

folding

Question 14

Deposition___erosion

Answer 14

faulting

Question 15

What creates earthquakes?

Answer 15

faulting

Question 16

Anticline and syncline are included in which geological observation?

Answer 16

unconformity

Question 17

What are 4 types of unconformity?

Answer 17

1) angular unconformity
2) disconformity
3) paraconformtiy
4) nonconformity

Question 18

What is angular unconformity?

Answer 18

buried topographic surface
*An angular unconformity is an unconformity where horizontally parallel strata of sedimentary rock are deposited on tilted and eroded layers, producing an angular discordance with the overlying horizontal layers.- via wikipedia

Question 19

Which unconformity includes “hiatus”?

Answer 19

angular unconformity

Question 20

What is hiatus?

Answer 20

apparent time erosion took place

Question 21

What is a disconformity?

Answer 21

A disconformity is an unconformity between parallel layers of rock which represents a period of erosion or non-deposition. - via wikipedia

Question 22

What is paraconformity?

Answer 22

• no strata
• ‘time gap’ or ‘rock gap’
• missing erosion
• [no strata deposited, no erosion]
• Rocks underneath not folded, tilted, faulted, etc.
• Erosion has not taken place
• Just a long time with no deposition
• Process just left no rocks but no real ‘time gap’

Question 23

What is the most significant type of unconformity?

Answer 23

angular unconformity

Question 24

What is the most common type of unconformity?

Answer 24

paraconformity

Question 25

What is nonconformity?

Answer 25

Non-volcanic rocks rest on crystalline rocks

Question 26

What begins the process of nonconformity?

Answer 26

Magma intrudes original strata

Question 27

What is contact metamorphism? What is regional metamorphism?

Answer 27

Contact metamorphism: modification by heat | Regional metamorphism: modification by heat if rocks are buried deeply

Question 28

What is fossil range?

Answer 28

every organism exist for a range of time--time span an organism lives.

Question 29

How long, on average, is the fossil range for various species?

Answer 29

6 million years (6 my)

Question 30

What does the fact that fossil range overlaps allow for?

Answer 30

more precise relative dating

Question 31

Where do local gaps in the fossil cord compared with more regional or global result?

Answer 31

unconformities

Question 32

Fossils, like living organisms, have specific___ranges.

Answer 32

geographic

Question 33

How do fossils replace one another?

Answer 33

In a definite, though complex, manner -- on both local and global scales (because of time ranges and environmental conditions)

Question 34

What are index fossils?

Answer 34

Fossils with a "short" time range, but which are broadly geographically distributed are especially useful.

Question 35

When did trilobites live from?

Answer 35

526-250 myo

Question 36

When did clams live for?

Answer 36

500-450 myo - present

Question 37

when did ginkgo live from?

Answer 37

270 - 0 may

Question 38

When did dinosaurs live for?

Answer 38

220 - 65 myo

Question 39

When was the largest extinction/

Answer 39

at end of paleozoic (250)

Question 40

What percent species became extinct at the end of paleozoic?

Answer 40

90%

Question 41

What percent of species when extinct at end of mesozoic?

Answer 41

70%

Question 42

When give dinosaurs go extinct?

Answer 42

65 myo

Question 43

What are the eons from oldest to youngest?

Answer 43

Oldest: Hadean Archean Proterozoic Youngest: Phanerozoic

Question 44

What are the eras of the phanerozoic eon (from oldest to youngest)

Answer 44

Oldest: paleozoic Mesozoic Youngest: Ceonozoic

Question 45

What were the major events of the Hadean eon?

Answer 45

- Birth of the earth and Solar System - Most asteroid impacts took place on moon--moon formed as well - Iron catastrophe (differentiation)

Question 46

When were the first life forms?

Answer 46

archean

Question 47

What are the 3 eons of the Precambrian?

Answer 47

Hadean Archean Proterozoic

Question 48

How many mya was Hadean?

Answer 48

4550

Question 49

How many mya was Archean?

Answer 49

3800

Question 50

How many mya was Proterozoic?

Answer 50

2500

Question 51

How many mya was Paleozoic?

Answer 51

250

Question 52

How many mya was Mesozoic?

Answer 52

65

Question 53

How many mya was Cenozoic?

Answer 53

0

Question 54

How many mya was the Phanerozoic?

Answer 54

542

Question 55

When were the 4 major extinctions?

Answer 55

~ 450 (Paleozoic) ~ 350 (Paleozoic) ~ 250 (Palaeozoic) (most significant) ~ 65 (Mesozoic)