How Noth America go its shape

Continents, countries, and even mountain ranges didn't always look the way they look now. Millions of years ago, every continent had a different shape. The force that changes continents and mountains is called tectonics, and each continent sits on a tectonic plate.

Read pages 28 and 29 in the textbook, and answer the questions.
Also think about why tectonic plates, volcanoes, and earthquakes are connected. link

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After watching the video, answer:

• What happens when one plate goes underneath another?
• What did the continents look like  millions of years ago? 
• What does "rift" mean? 
• Name the different tectonic plates in this region on the video