EXAM 1 Questions

Question 1

Why do geologists refer to the last 2 to 3 million years of Earth’s history as the “Modern Ice Age, i.e. how has the last 2 to 3 million years of Earth’s history differed from earlier history?

Answer 1

1

Question 2

What evidence exists to show that Earth’s climate became much colder ~3 million years ago?

Answer 2

1

Question 3

The cold Arctic region effectively cools the world: What keeps the Arctic region cold today?

Answer 3

1

Question 4

How and why were large-scale ocean currents different prior to ~3 million years ago than they are today?

Answer 4

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Question 5

For any given place on Earth, what are some of the factors that control climate?

Answer 5

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Question 6

Major ice ages, similar to the one we live in today, have occurred several times during Earth’s history. Did the conditions leading to these ice ages evolve relatively slowly or quickly?

Answer 6

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Question 7

During the ice age we live in now, what has controlled the cycling between Glacial and Interglacial periods?

Answer 7

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Question 8

At the subatomic level, what is unique to each of the known elements in the Periodic Table?

Answer 8

Different number of protons.

Question 9

How does one isotope of oxygen differ from another isotope of oxygen?

Answer 9

Number of neutrons

Question 10

Explain why fractionation takes place when water is evaporated from the ocean.

Answer 10

Fractionation applies to a process that changes the relative amount of isotopes in a water. The proportion of O16 and O18 in water. Process is evaporation (dependent on temp and mass of molecule)

Question 11

How does the percentage of H218O occurring in snow or rain differ when it’s warm vs when it’s cold?

Answer 11

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Question 12

At any place in a long ice core retrieved from the Greenland Ice Sheet, how do geologists know how old the ice is?

Answer 12

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Question 13

When did the last interglacial period, the one we’re living in now, begin?

Answer 13

10,000 years

Question 14

Was the change from the last glacial period to the current interglacial period occur smoothly over a long period of time or abruptly over a relatively short period of time?

Answer 14

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Question 15

Compare the stability of Earth’s temperature during the interglacial period we live in (the last 10,000 years) and the last glacial period (~120,000 to 10,000 years).

Answer 15

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Question 16

What are the necessary conditions for glacier to form?

Answer 16

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Question 17

What are some of the processes occurring as snow changes to glacial ice?

Answer 17

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Question 18

As snow changes to glacial ice, its density increases. What is the principle process causing the density to increase?

Answer 18

Compaction from greater weight of snow. the snow is mostly air which is forced out.

Question 19

What are some of the ways that continental ice sheets differ from alpine glaciers?

Answer 19

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Question 20

If alpine glaciers move down the valleys they lie in, what determines the direction that continental ice sheets move?

Answer 20

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Question 21

What is the source of energy causing glaciers to move?

Answer 21

1

Question 22

Where do alpine (or valley) glaciers move most quickly?

Answer 22

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Question 23

What are the different processes that contribute to the motion of glaciers?

Answer 23

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Question 24

What is the evidence, the frequent observation on rock surfaces, that glaciers are capable of sliding along their bases?

Answer 24

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Question 25

What is the evidence, the frequent observation within glaciers, that glaciers are capable of deforming in a ductile manner (smoothly, without cracking)?

Answer 25

1

Question 26

What is the evidence, the frequent observation within glaciers, that glacier behave in a brittle manner (they crack and break) near their surfaces?

Answer 26

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Question 27

What is the difference between the accumulation zone and the ablation zones on glaciers?

Answer 27

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Question 28

What is the relationship between the mass balance of a glacier and the position of that glacier’s terminus with time?

Answer 28

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Question 29

Compare/contrast the processes of glacial abrasion and glacial quarrying.

Answer 29

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Question 30

How can roches moutonneé be used to determine what direction a glacier was flowing?

Answer 30

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Question 31

How and why are the shapes of valleys eroded by glaciers different from the shapes of valleys eroded by streams?

Answer 31

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Question 32

How do hanging valleys form?

Answer 32

1

Question 33

What are some of the characteristic features of glacial cirques?

Answer 33

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Question 34

Cirques are generally eroded in the accumulation zone/equilibrium line/ablation zone of glaciers (choose one).

Answer 34

Accumulation Zone

Question 35

How does a glacial horn differ from a glacial arêtes?

Answer 35

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Question 36

What is similar and what is different about the processes producing glacial horns and glacial arêtes?

Answer 36

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Question 37

Give a definition of glacial till.

Answer 37

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Question 38

In New England, where, relative to the ice sheet that used to cover the area, was most till deposited?

Answer 38

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Question 39

What is a glacial erratic?

Answer 39

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Question 40

How can erratics be used to help determine the direction that glaciers flowed?

Answer 40

Erratics are uplifted rocks from different areas, these rocks can be traced to their original location.

Question 41

What are two processes that can produce end moraines?

Answer 41

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Question 42

What are some of the attributes of moraines that make them distinctive, that allow you to see them?

Answer 42

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Question 43

How do medial moraines form?

Answer 43

1

Question 44

How do glacial kettles form?

Answer 44

1

Question 45

How is glacial outwash different from glacial till?

Answer 45

1

Question 46

How are sediments classified by size?

Answer 46

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Question 47

Relative to the direction that a glacier is flowing, describe the shape of drumlins produced by that flowing ice.

Answer 47

Drumlins are elongated asymmetrical hills with a gradual slope faces downstream. Step end faces glacier. The long axis is parallel to the flow of the glacier.

Question 48

What kind of sediment occurs in an esker?

Answer 48

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Question 49

In the ablation zone of glaciers, what happens to water generated by melting snow and ice? Describe the pathways it follows across and through a glacier.

Answer 49

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Question 50

What can happen to the speed of a glacier as more water reaches its base?

Answer 50

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Question 51

What are some of the feedback mechanisms that can cause an ice sheet to rapidly disintegrate?

Answer 51

Climate is warming, more snow/ice is melting than falling. Water moves to base and moves it faster downgrade to ocean.

Question 52

What is the evidence you would look for to know that a lake used to exist somewhere?

Answer 52

1

Question 53

During what time frame, approximately, was the Laurentide ice sheet retreating across New England?

Answer 53

At it's maximum extent about 25,000 years ago, 13,000 years is was near Champlain Valley

Question 54

Many glacial lakes occurred in Vermont and elsewhere in New England as the ice sheet was retreating. What were the geographical constraints that allowed lakes to form in some areas?

Answer 54

A closed basin is needed for the lake to form. Naturally occurring rock dam was formed at the north end of the lake.

Question 55

How can we determine the elevation of the glacial lakes that used to exist here?

Answer 55

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Question 56

Why is it that the shorelines of these old glacial lakes, that were horizontal when they formed, are now tilted upwards to the northwest?

Answer 56

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Question 57

When the land surface sinks as an ice sheet grows on the land surface, what is flowing out of the way and where does it go?

Answer 57

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Question 58

Compare the strength of the Lithosphere vs the Asthenosphere.

Answer 58

Lithosphere is a stiff and strong (sinks), Asthenosphere is weaker (fluid and viscus).

Question 59

Isostatic changes to the land surface in response to adding or subtracting the load of a continental ice sheet are relatively fast or slow? What processes govern the speed?

Answer 59

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Question 60

Where, approximately, was the Laurentide ice sheet when the Champlain Sea formed?

Answer 60

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Question 61

How was it possible that the much of the Champlain valley and adjacent St Lawrence valley were flooded with sea water for several thousand years following the retreat of the ice sheet?

Answer 61

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Question 62

What evidence exists in sediments occurring in the Champlain valley that the area was flooded with salt water?

Answer 62

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Question 63

What is meant by the term “Periglacial?”

Answer 63

At the edge of a glacier environment (does not need to be a glacier) avg. temp -5C. permafrost. Conditions for glaciers to from is not there.

Question 64

What landforms frequently develop in areas with permafrost?

Answer 64

Patterned Land: Polygonal Patterns formed from ice melting in the soil and cracking. Very boggy areas and wet

Question 65

What frequently occurs to buildings and forests in areas where permafrost is melting?

Answer 65

Sink

Question 66

How is it that changes in climate are recorded in the changing temperature with depth in a hole drilled into permafrost?

Answer 66

The permafrost layer is slowly changed by the climate and therefore the temperature profile is gradually slopped instead of jagged like air temp.

Question 67

Why can long-term records of the size of glaciers be used as a measure of climate change?

Answer 67

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Question 68

Why were Scandinavians able to settle in Greenland beginning in 985 AD?

Answer 68

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Question 69

Why are temperature measurements of permafrost a better measure of climate change than temperature measurements in air?

Answer 69

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Question 70

What is the “active layer” in permafrost regions?

Answer 70

The top meter or so that melts in the summer and allows plants to grow.

Question 71

Why may melting permafrost accelerate global warming?

Answer 71

Release methane and other greenhouse gases from decomposing plant material underneath.

Question 72

How can you tell the difference between sea ice that’s seasonal and sea ice that’s permanent?

Answer 72

Seasonal sea ice has more salt in it. Permanent sea ice forces the salt out.

Question 73

What is “albedo” and how does it differ between snow, ice, land, and water?

Answer 73

Is the reflectivity of a surface to sunlight. Snow (0.01) has a high albedo, ice (0.1) is lower, followed by land (0.3-0.8) and water (0.9)

Question 74

Compare how easily visible light passes through oxygen, nitrogen, carbon dioxide, water vapor, and methane.

Answer 74

All transparent

Question 75

Compare how easily infrared radiation passes through oxygen, nitrogen, carbon dioxide, water vapor, and methane.

Answer 75

Passes mostly through Oxygen, Nitrogen. Reflected or absorbed by CO2, water vapor and methane. Tyndal Discovery 1850

Question 76

Why does the Keeling Curve make annual up and down swings?

Answer 76

The Keeling Curve shows the amount of CO2 in the atmosphere, the swings result from summer and winter. CO2 is higher in the winter because plants are hibernating.

Question 77

What processes cause barrier islands to move as relative sea level rises (or falls)?

Answer 77

As one part shrinks another part moves by erosion along/ toward mainland.

Question 78

What processes can cause the volume of water in the oceans to change?

Answer 78

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Question 79

What processes can cause the land surface to rise or fall?

Answer 79

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Question 80

Explain the different relative age dating principals.

Answer 80

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Question 81

When describing radioactive decay, what is the difference between a “parent” and “daughter” isotope?

Answer 81

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Question 82

What is meant by the “half life” of a radioactive isotope?

Answer 82

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Question 83

How can zircon crystals be used to date rocks?

Answer 83

Newly grown crystals only include uranium, as it ages the uranium breaks down into lead. The proportion of U to Pb can be used to calc age.

Question 84

Where and how is Carbon-14 generated?

Answer 84

In the atmosphere by cosmic rays hitting atoms. Stray neutrons hit nitrogen, and then a proton comes out causing the nitrogen to become Carbon-14

Question 85

How is Carbon-14 incorporated into living organisms?

Answer 85

Carbon-14 forms with O2 to make CO2 that is used by plants and animals

Question 86

Why can’t Carbon-14 be used to date materials that are older than ~50,000 years?

Answer 86

C-14 has a short half life, after 10 half lives the amount left is undetectable. Coal is carbon rich but millions of years old, no C-14 left.

Question 87

When did Earth form? What has been dated to come up with this date?

Answer 87

4.56 Billion years ago. Zircon Crystals.

Question 88

When did fossils first become large and abundant on Earth?

Answer 88

540 million years ago during the