Moving plates, and the clues that they move

Grade 6 Science Worksheet - Challenge Me

Circle the best answer.

1. 1.

   2.5 cm each year = about 25 km each million years; 10 million years. At about 2.5 cm a year, how much wider could the Atlantic be in 10 million years? Esme uses the USGS figure of 25 km per million years.

   • About 25 km
   • About 250 km
   • About 2,500 km
   • No wider; continents are fixed
2. 2.

   India is still pushing into the rest of Asia today. What does Jun predict for the Himalayas?

   • They will grow kilometers taller in a few years
   • They will sink as the plates pull apart
   • They keep being pushed up, very slowly
   • Nothing; the collision is over
3. 3.

   Along the San Andreas Fault, two plates slide past each other. Over millions of years, what does Kira predict for towns on opposite sides?

   • They swap sides of the fault within one lifetime
   • They crash together into mountains
   • They stay exactly where they are
   • They slowly shift far apart, sideways
4. 4.

   Luz's friend says Mesosaurus swam across the ocean between Africa and South America. Which response is best?

   • Disagree: it lived in fresh water; the lands were joined then
   • Disagree: it walked over a land bridge
   • Agree: reptiles can swim great distances
   • Agree: the continents have stayed right where they are today, so it swam
5. 5.

   A video says continents race around at kilometers per year. Milo checks USGS. Which response is best?

   • Disagree: plates move a few centimeters a year
   • Disagree: plates do not move
   • Agree: you can watch coastlines move from one year to the next
   • Agree: plates surf fast on liquid lava

6. Read this first

   Use this

   Cross-section, not to scale:

7. 6.

   Noah's cousin says the oldest seafloor is found at the mid-ocean ridges. Which response is best?

   • Agree: ridges are where plates crash
   • Disagree: seafloor is one age everywhere
   • Agree: ridges are where the oldest rock slowly piles up in heaps
   • Disagree: the youngest is at ridges; it gets older outward
8. 7.

   Ren looks for evidence that the seafloor spreads. Which observation is the best evidence?

   • Ridges have no earthquakes
   • The ocean is deepest near the coasts
   • The ridge sits mid-ocean, so its rock must be the oldest there
   • Rock gets older moving away from the ridge on both sides
9. 8.

   Zee cuts out paper continents and slides them together to show Pangaea. What else should the model show?

   • The continents moving apart in a few days
   • The continents fixed in today's places
   • The continents floating on water in a big tub, like rafts
   • Matching fossils and rocks lining up across the joins
10. 9.

    “(teacher only)” The teacher gently warms one side of a pan of thick, gooey liquid with cracker pieces on top, and the pieces drift. What do the pieces stand for, says Ari?

    • Earthquakes shaking the crust
    • Plates riding on slowly moving mantle rock
    • Continents floating along on top of a liquid lava ocean
    • Plates that stay fixed
11. 10.

    Bo pushes two stacks of paper together on a table, and they buckle upward where they meet. Which feature does this model?

    • A trench from plates pulling apart
    • A ridge at a divergent boundary
    • A transform fault
    • Mountains at a convergent boundary