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3.4Unit 5: Atoms, purity and climate

Climate and ice ages — Cambridge Checkpoint Earth & Space 0893 Revision Notes & Topical Questions

5 min read 8 parts Lesson 4 of 5 1 quiz

📚 Cambridge Checkpoint Earth & Space 0893 Hub / Topical Revision
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Lesson summary

3.4 Climate and ice ages — CHECKPOINT EARTH AND SPACE 0893 notes: Describe glacial and interglacial periods and ice ages and the evidence that the climate has changed.Colder Earth — about 25 000 years ago much of the Earth was covered by ice sheetsPreservation — frozen soil in pl…

  • Today's ice
  • Ice in an interglacial
  • Ice in a glacial
  • Warm periods
  • Cold climate
  • Warm climate

Section 1 of 8Ice sheets in the past

Colder Earth
  • Colder Earth about 25 000 years ago much of the Earth was covered by ice sheets
Preservation
  • Preservation frozen soil in places such as Siberia preserves bodies like the mammoth Yuka for thousands of years
Today's ice
  • Today's ice ice covers mainly the regions near the North and South Poles

Section 2 of 8Glacial and interglacial periods

1Glacial period
Glacial period a very cold period when much of the Earth was frozen
2Interglacial period
Interglacial period a warmer period between glacial periods
3Present
  • Present the Earth is in an interglacial period, since the last glacial period ended about 10 000 years ago
4Cycle
  • Cycle over the last 450 000 years the climate has swung between glacial and interglacial periods
5Ice in an interglacial
  • Ice in an interglacial permanent ice is close to the North and South Poles
6Ice in a glacial
  • Ice in a glacial ice spreads much further south from the North Pole and further north from the South Pole

Section 3 of 8Ice ages

Ice age
Ice age a long cold period containing glacial and interglacial periods
Warm periods
  • Warm periods between ice ages the Earth was so warm that there was no permanent ice even at the poles
Number
  • Number scientists think there have been several ice ages
Coldest
  • Coldest they think the ice age starting about 850 million years ago was the coldest, and the whole Earth may have been like a giant snowball

Section 4 of 8Evidence from glaciers

Glaciers
Glaciers rivers of ice that move slowly downhill, formed from snow compressed into thick ice
Boulders
  • Boulders rocks left in odd places were carried by ancient glaciers that later melted
Scratches
  • Scratches moving ice drags rocks across other rocks and scratches their surfaces
Fossils
  • Fossils fossils of plants and animals adapted to cold places are found where it is now warm
Valleys
  • Valleys glaciers left their mark by carving deep valleys

Section 5 of 8Evidence from pollen in peat

1
Peat forms in bogs where plants decay very slowly without oxygen in slightly acid conditions.
2
Scientists take a core of peat with an auger and keep the layers in the correct order.
3
Deeper layers are older, and the deepest in the example formed 237 000 years ago.
4
Pollen is collected from each layer and the plants it came from are identified.
5
Each plant lives in a known type of climate, so the climate at each time can be worked out.

Section 6 of 8What pollen layers showed

Cold climate
  • Cold climate grassland increases, forest decreases, and vegetation suits a glacier nearby
Warm climate
  • Warm climate mainly lowland forest
Cycle
  • Cycle the climate cools, then warms and the ice retreats, in a repeating cycle

Section 7 of 8Key terms

TermMeaning
Glacial periodVery cold period when ice spreads widely.
Interglacial periodWarmer period between glacial periods.
Ice ageLong cold period of glacial and interglacial periods.
GlacierRiver of ice that moves slowly downhill.
PollenPowder from plants used to identify past plants.
PeatSlowly decayed plant material that forms in bogs.

Section 8 of 8Exam technique

1
Thinking the Earth is in a glacial period now — it is in an interglacial period.
2
Mixing up an ice age and a glacial period — an ice age is a long cold period that contains glacial and interglacial periods.
3
Thinking glaciers are made of frozen sea water — they form from compressed snow.
4
Believing the Earth has always been cold — long warm periods had no permanent ice.

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