During an Ice Age, when the world is colder, more of the world’s water freezes into ice. This means that less water is in the oceans than before and the sea level becomes lower. Because the ocean level is lower, more of the land sticks out. As the ice age comes to an end, the ice melts and fills the oceans, making the sea level rise and covering those same lower elevation bits of land once again. Geologists theorize that this phenomenon caused a land bridge to form between east Asia and North America long ago.
During the last Ice Age this land bridge would have led from from Siberia to Alaska, and most archaeologists think that people and animals actually made the crossing to North America. These probably weren’t the first people to come from Central Asia to North and South America – seeing how it’s not a great distance, chances are that some made the voyage by boat. The Vikings definitely managed it on the eastern side of North America.
As part of a unit study on the Ice Age, my kids and I made this land bridge model to represent the possible land bridge that may have connected Asia and North America.
We began by making homemade salt dough. We shaped it to form 2 continents that were connected by a slightly lower elevation bridge of land. Next we put a little blue food coloring in some water and poured it until it was just below the land bridge. We put ice cubes throughout, both in the water and on the continents. As the ice melts, it causes the water level to rise and covers the land bridge with “ocean.” If you look closely you can still see the land under the water in the center. By the end the ice that has melted on the continents also fills in little lakes and looks pretty neat.
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