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?

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

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

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

3. Read this first

   Use this

   Map of an ocean floor colored in matching bands on both sides of a ridge in the middle; the color key runs from youngest to oldest.

4. 3.

   Kira's map of the ocean floor is colored by rock age, with a ridge down the middle. Where is the youngest seafloor rock?

   • Spread evenly everywhere
   • In the deepest trenches
   • Near the coasts on each side of the ocean
   • At the ridge in the middle of the ocean
5. 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?

   • Old seafloor forms at the ridge
   • The seafloor stays put
   • The coasts make new seafloor
   • New seafloor forms at the ridge and spreads outward
6. 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?

   • Ocean currents painted the stripes
   • Each side formed at a different coast
   • The plates crashed together there
   • The seafloor formed at the ridge and spread both ways
7. 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
8. 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 km
   • About 25 m
   • About 2,500 km
   • About 2.5 km
9. 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.

   • Yes: that adds up to about 5,000 km
   • No; centimeters are too small to add up
   • No; the Atlantic has stayed this wide
   • Yes, but just if plates move meters a year
10. 9.

    World map with earthquake and volcano dots crowded in lines around the Pacific Ocean. On a world map of earthquakes and volcanoes, the dots form lines around the edge of the Pacific Ocean. Why, by Tala's reasoning?

    • They mark where plates stand still
    • They mark the hottest places on the surface
    • They mark plate boundaries
    • They mark where the mantle is liquid lava
11. 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
    • A mid-ocean ridge
    • Divergent