Moving plates, and the clues that they move

Grade 6 Science Worksheet - Building Confidence

Circle the best answer.

1. 1.

   Cross-section, not to scale. Ari's cross-section shows two plates with arrows pointing away from each other and magma rising between them. Which kind of boundary is it?

   • Convergent: plates push together
   • No boundary; plates don't move
   • Divergent: plates pull apart
   • Transform: plates slide past
2. 2.

   Seen from above, Kira's map shows two plates with arrows pointing in opposite directions along their shared edge. Which kind of boundary is it?

   • No boundary; the ground is just cracked
   • Convergent: plates push together
   • Divergent: plates pull apart
   • Transform: plates slide past each other
3. 3.

   The coasts of South America and Africa fit together like puzzle pieces. What does Jun conclude?

   • It is just a coincidence
   • They are rushing toward each other right now
   • They were once joined and have moved apart
   • Sea water carved them to match
4. 4.

   Map of South America and Africa today, with matching fossil marks on the two coasts across the Atlantic Ocean. Fossils of Mesosaurus, a small freshwater reptile, turn up in both South America and southern Africa. What explains this, by Luz's reasoning?

   • The continents were joined when it lived
   • It swam across the Atlantic Ocean
   • Its fossils floated over on pieces of driftwood
   • It walked across a long land bridge
5. 5.

   Fossils of the same ancient plant, Glossopteris, appear in South America, Africa, India, Antarctica and Australia. What does Milo conclude?

   • Its seeds blew across the oceans
   • Those lands were once joined together
   • Those lands are still joined today
   • Each land grew it separately by chance
6. 6.

   Noah reads the USGS page on plates. About how fast do plates move?

   • A few centimeters a year
   • A few meters a day
   • A few kilometers a year
   • They don't move
7. 7.

   USGS compares the speed of plates with something that grows on Pia's own hands. What is it?

   • A snail crawling
   • Fingernails growing
   • Nothing; plates are fixed
   • A car on a highway
8. 8.

   Ren wonders why nobody notices the continents moving. Which answer is right?

   • They move just a few centimeters a year
   • They don't move
   • They move just at night
   • They move too fast to see
9. 9.

   An ocean plate bending down under another plate, with the place where they meet unlabeled. Where an ocean plate sinks under another plate, what forms? Tala checks the cross-section.

   • A tall ridge of brand-new seafloor rock
   • A deep trench, with volcanoes nearby
   • A long sliding fault
   • A lava ocean opening up
10. 10.

    Cross-section, not to scale: two ocean plates moving apart, with magma rising between them under the sea floor. Where two ocean plates pull apart, what forms on the sea floor, according to Zee's book?

    • An open gap down to liquid lava
    • Tall mountains pushed up by crashing plates
    • A trench, where crust sinks
    • A ridge, where magma makes new crust