ICE AGES

1
ICE AGES

• Glacials and Interglacials

2
Defining terms

• GLACIAL
• INTERGLACIAL
• INTERSTADIAL
• PERIGLACIAL
• PROGLACIAL
• FLUVIOGLACIAL

3
ICE AGE CAUSES

• PLANETARY MOTION
• The MILANKOVICH CYCLES

4
ICE AGE CAUSES

• CONTINENTAL DRIFT and OCEAN CURRENTS
• THERMOHALINE CIRCULATION
• MOUNTAIN BUILDING (Orogeny)
• ATMOSPHERIC CHANGES
• ALBEDO (Positive Feedback)
• Remember the response time ice sheets will take
  100 000 years to start to react they are slow
  things after all smaller ice masses will react
  more quickly

5

• Last major ice advance was the PLEISTOCENE from
  125 000 to 18 000 years BP (Before Present)
• What other ice advances have there been check
  the textbook for more!

6
What happens next ?

• The key to ICE formation is that the SNOW which
  falls in one winter lasts through the intervening
  summer period and the next winters snow then
  falls on top.
• This begins the process of DIAGENESIS which will
  take about 40 years to produce glacier ice.
• The important thing is to increase the density of
  the material by squashing out the air, or
  removing it by thawing and refreezing
  (REGELATION)
• How does glacier ice vary from the ice that forms
  in a freezer or on road surfaces ?
• POSER Why is black ice so called ? Is it
  really black ?

7
Essay Question

• Explain how snow becomes glacier ice
• (5 marks)
• Outline the reasons for the transition from
  interglacial to glacial which has occurred
  numerous times throughout the earths history
• (20 marks)