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Starter:. 1. What would happen if it snowed all winter in this country and then the snow didn’t melt in the summer? 2. Would different parts of the country be affected differently? Why ?. L.O.s To Define the terms Ice Age, Pleistocene, Glacials and Interglacials .
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Starter: 1. What would happen if it snowed all winter in this country and then the snow didn’t melt in the summer? 2. Would different parts of the country be affected differently? Why?
L.O.s To Define the terms Ice Age, Pleistocene, Glacials and Interglacials. To compare ice cover now and in the last Ice Age. To explain why we have ice Ages at all.
So what is an Ice Age? • An Ice Age is a period of time during which glaciers covered a large part of the earth's surface. • Roughly every 200 to 250 million years in the Earth’s history there have been major periods of Ice activity. • Like Antarctica and Greenland today, many parts of the world have been covered with Ice. • The most recent and significant Ice Age occurred during the PLEISTOCENE period which started 2 million years ago.
An ice sheet is a moving mass of ice which covers a large land surface area. In Antarctica the ice is 4000m thick.
A Natural History of Europe Episode 3: Ice Age. • Play from 3.30 mins to 10.12 mins.
Surprisingly The Ice Age has not ended! • There are warm periods called interglacials • It is likely that we are in an interglacial period now. • These are temporary warm periods when the climate warms and the ice retreats and sea levels rise. Glacial are the cold periods It is believed that there have been 20 glacial periods in the last 2 million years
Ice Cover in the last glacial period 20,000 years ago Ice Cover Present Day – an interglacial period
Tasks On your worksheet • Annotate/Label the areas with Ice 20,000 years ago and those with Ice now. • Compare the Ice cover 20,000 years ago at the end of the last Glacial period with the Ice cover today. Success Criteria: • Identify areas with Ice by using names of continents, mountain ranges, seas and countries – try using compass directions to be more precise. • When comparing describe similarities and differences.
Just out of interest… do you know what might cause an ice age?
Well... • Changes in the circulation of the atmosphere and the oceans. Winds and ocean currents help to circulate heat from the equator towards the poles. If those currents get disrupted then some areas could get very cold very quickly.
2. The Earth sometimes receives less heat from the sun due to: • A decrease in the sun’s energy output caused by sun spots • An increase in atmospheric dust caused by volcanic eruptions • A change in the Earth’s orbit taking it further from the sun
Next Lesson • How do we know that we have had 20 glacial period in the last 2 million years of Geological history? • Where’s the evidence?