Plate Tectonics 6th Grade

What did Alfred Wegener think happens continental drift?

• Continents move

• Continents freeze

• Convection stops

• The mantle warms

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NGSS.MS-ESS2-3

Wegener thought that all the continents were once joined together in a supercontinent that he called

• Pangaea

• The first continent

• The Appalachian

• Old England

Choose all observations that provided evidence that was used to develop the theory of Pangaea

• Mountain ranges on continents line up

• Fossils of reptiles that can only be found on one continent were found on other continents

• Fossils of tropical plants were found in cold climates

• There were lines in the ocean from where the continent moved along the bottom

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NGSS.MS-ESS2-3

NGSS.MS-ESS2-2

NGSS.MS-LS4-1

In which areas does subduction of the ocean floor take place?

• rift valleys

• mid-ocean ridges

• the lower mantle

• deep-ocean trenches

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NGSS.MS-ESS2-3

A mid- ocean ridge is a __________ that rises up from the ocean floor

• mountain range

• lava field

• cave

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NGSS.MS-ESS2-3

Why are the oldest parts of the ocean floor no older than about 200 million years old?

• That is how long it takes for sand to completely cover the ocean floor

• That is how long it takes for new crust to form, move across the ocean and sink into a trench

• Underwater volcanoes erupt every 200 million years and create a new ocean floor

Tags

NGSS.MS-ESS2-3

NGSS.MS-ESS2-2

Which is the FIRST step of sea-floor spreading?

• The molten material cools and hardens, forming a strip of rock along the ocean floor

• The strip of rock moves away from the ridge

• Molten material from inside Earth rises to the ocean floor at a mid-ocean ridge

Which is the SECOND step of sea-floor spreading?

• The molten material cools and hardens, forming a strip of rock along the ocean floor

• The strip of rock moves away from the ridge

• Molten material from inside Earth rises to the ocean floor at a mid-ocean ridge

Which is the THIRD step of sea-floor spreading?

• The molten material cools and hardens, forming a strip of rock along the ocean floor

• The strip of rock moves away from the ridge

• Molten material from inside Earth rises to the ocean floor at a mid-ocean ridge

How is pillow lava evidence of sea-floor spreading?

• It can only happen when molten material hardens quickly after erupting underwater

• It is lined up in the direction of Earth's magnetic fields

• It is older than the rest of the rock on the ocean floor