week 6 Lecture part 1

Question 1

When did the quaternary happen?

Answer 1

2,588,000 Myr ago to present day

Question 2

What is the quaternary broken into?

Answer 2

Divided into the Pleistocene (2,588,000 to 11,200
years ago) and Holocene (11,200 years ago to present)

Question 3

What are the key features of the quaternary?

Answer 3

Continents were at (or very near) their current position
Colder than during most of Earth’s history
Characterised by glacial-interglacial cycles
Backdrop to human evolution

Question 4

What time scales does orbital variation happen over?

Answer 4

10,000’s to 100,000’s of years

Question 5

What is Eccentricity?

Answer 5

changes in the shape of Earth’s orbit as it
rotates around the sun

Question 6

What is Obliquity?

Answer 6

(axial tilt) – changes in the angle of tilt of
Earth’s axis of rotation

Question 7

What is precession?

Answer 7

the timing of the seasons around the non- circular orbit

Question 8

What is the effect of Eccentricity

Answer 8

affects the amount of solar radiation received
Overall a relatively small impact

Question 9

What is the Perihelion?

Answer 9

Point where Earth is closest to the sun(Eccentricity)

Question 10

What is the Aphelion?

Answer 10

Point where Earth is furthest from the sun(Eccentricity)

Question 11

What time scale does Eccentricity work on?

Answer 11

100,000 year cycle(also 413 000 years)

Question 12

What is the tilt in the earth’s axis called?

Answer 12

obliquity

Question 13

What does obliquity cause and effect?

Answer 13

effects the amount of solar radiation received
is why the earth has seasons

Question 14

What time scales does obliquity work on?

Answer 14

41,000-year cycle

Question 15

What does greater axial tilt result in?

Answer 15

more extreme seasons

Question 16

What is the first component of precession?

Answer 16

Axial Precession

Question 17

What is the time scale of axial precession?

Answer 17

25,700-year cycle

Question 18

What is the second component of precession?

Answer 18

Elliptical Precession

Question 19

What is the time scale of Elliptical precession?

Answer 19

120,000-year cycle

Question 20

What is the time scale overall of precession?

Answer 20

23,000-year cycle

Question 21

Why is summer insolation at 65°N critical?

Answer 21

• Must be cool enough in summer for the ice to persist
• There is more land at the mid to high latitudes in the Northern Hemisphere -Greenland, North America, Russia, Europe

Question 22

What orbital conditions result in ice growth?

Answer 22

Low obliquity - small seasonal contrast
Low eccentricity and NH summer occurs at aphelion – cooler NH summers

Question 23

What orbital conditions result in ice melt?

Answer 23

High obliquity – large seasonal contrast
NH summers at perihelion – warmer NH summers