Moving plates, and the clues that they move

Grade 6 Science Worksheet

Circle the best answer.

1. 1.

   Iceland sits on the Mid-Atlantic Ridge, where the land is slowly splitting apart. Which kind of boundary is Bo reading about?

   • Divergent
   • Convergent
   • No boundary; Iceland is fixed
   • Transform
2. 2.

   The Himalayas formed as India pushed into the rest of Asia. Which kind of boundary made them, in Esme's notes?

   • Divergent: plates pulling apart from each other
   • A lava ocean pushing them up
   • Transform: plates sliding past
   • Convergent: two plates colliding
3. 3.

   Map of California with the San Andreas Fault drawn and arrows on each side pointing in opposite directions along it. The San Andreas Fault in California is one of the few transform boundaries on land. What do its two plates do, by Jun's reading?

   • Push together into a trench
   • Pull apart to make a ridge
   • Sit still, since faults don't move
   • Slide past each other
4. 4.

   Cross-section, not to scale: a ridge with age labels increasing in both directions away from it. Seafloor rock gets older the farther it is from a mid-ocean ridge, on both sides. What does this show, according to Luz?

   • New seafloor forms at the ridge and spreads outward
   • The coasts make new seafloor
   • Old seafloor forms at the ridge
   • The seafloor stays put
5. 5.

   Map view of a ridge with matching light and dark stripes on each side, mirror images of each other. Magnetic stripes in the seafloor make the same pattern on both sides of a ridge, like a mirror. What does Milo conclude?

   • The plates crashed together there
   • The seafloor formed at the ridge and spread both ways
   • Each side formed at a different coast
   • Ocean currents painted the stripes
6. 6.

   2.5 cm each year; 100 years. The Mid-Atlantic Ridge spreads about 2.5 cm a year (USGS). How much wider does the Atlantic get in 100 years, by Noah's math?

   • About 2.5 cm
   • About 2.5 m
   • No wider
   • About 250 km
7. 7.

   2.5 cm each year; 1,000,000 years; 100,000 cm = 1 km. At about 2.5 cm a year, how far does the Atlantic widen in 1 million years? Pia works it out.

   • About 25 m
   • About 25 km
   • About 2.5 km
   • About 2,500 km
8. 8.

   2.5 cm each year; about 200,000,000 years; 100,000 cm = 1 km. Pangaea began to break up about 200 million years ago. Could 2.5 cm a year open an ocean thousands of kilometers wide in that time? Ren checks.

   • No; the Atlantic has stayed this wide
   • Yes, but just if plates move meters a year
   • Yes: that adds up to about 5,000 km
   • No; centimeters are too small to add up
9. 9.

   Zee compares an earthquake map with a plate map. Where do most earthquakes happen?

   • Along plate boundaries, where plates grind and push
   • Evenly everywhere on Earth
   • In the middle of plates, far from the edges
   • Where plates float on liquid rock
10. 10.

    The Andes mountains have many volcanoes where an ocean plate sinks under South America. Which kind of boundary is Ari looking at?

    • Convergent
    • Transform
    • Divergent
    • A mid-ocean ridge