Lecture 3

Question 1

What can causes a change in surface level of the earth

Answer 1

Magma chambers can expand and contract, especially around eruptions and this can change the level of the surface surrouning

Question 2

What can cause shorelines to change quickly

Answer 2

Earthquakes

Question 3

What can cause global sea level change

Answer 3

Growth and decline of ice sheets. Between 15,000 and 6,000 years the sea level rose roughly 120m

Question 4

What period of ice are we in

Answer 4

Interglacial

Question 5

Interglacials

Answer 5

period of time with little ice

Question 6

Glacials

Answer 6

Periods with more ice and lower sea levels

Question 7

What is a pile of boulders left by glaciers

Answer 7

Boulder clay, or till

Question 8

How do glaciers cause striations

Answer 8

drags rocks along and cause drag marks

Question 9

What shape is common in boulder clay?

Answer 9

Triangular

Question 10

Two types of foraminifera
(forams)
And why they are useful

Answer 10

1. Planktonic—>shallow seas
2. Benthic—>ocean floor

typically <1mm in size and are useful paleoenvironment indicators
But better is that CaCO3 shells contain record of oxygen composition of sea water

Question 11

Oxygen isotope ratio use

Answer 11

18 and 16 are the main two stable isotopes of oxygen and the ratio can tell if more or less ice on earth.

16 is lighter and 500 times more abundant and evaporates more easily from sea water
Permanent ice caps exist then sea water increased 18 as the evaporated 16 stored in ice

Question 12

What also affects the ratio in foraminifera?

Answer 12

Temperature as they take up more 18 when its cold.

This is an example of biological fractionation

Question 13

How to get around the problem of temperature affecting ratio?

Answer 13

Use benthic as ocean floor has smaller variation in temperature and so the ratio is mainly affected by ice levels

Question 14

Which three scientists in 1976 made a breakthrough in explaining the causes of the isotope variation?

Answer 14

Hays
Imbrie
Shackleton

Question 15

What prediction did the pattern of climate variation follow?

Answer 15

Milankovitch in 1941

Who used celestial mechanics

Question 16

What are the three main orbital effects?

Answer 16

1. Eccentricity (the elliptical orbit changes by 6% over 100,000 year period)
2. Tilt/Obliquity (orbital plane varies between 21.8 and 24.4 degrees-affects distribution of solar energy)
3. Precession (Earth’s axis wobbles like a spinning top with a period of 22,000 years)

Question 17

These aren’t completely accurate (the prediction from the three orbital effects) WHY?

Answer 17

Because of other climate variations
Like Albedo feedback where ice reflects more energy so causes it to get colder
or positioning of the movement in the oceans as movement of equitorial water (warmer) to poles

Question 18

What is a drop rock?

Answer 18

A rock that icebergs have dropped onto the sea floor when they melt

Question 19

Indicators and analysis of what features can tell the ages of previous ice ages?
x 4

Answer 19

Glacial striations
Varves
Drop-stones
Boulder clays

Question 20

Ice ages are rare when where the last three?

Answer 20

1. 260-270 Ma
2. 410-440 Ma
3. 1000-600 Ma