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

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

   • They will sink as the plates pull apart
   • They will grow kilometers taller in a few years
   • Nothing; the collision is over
   • They keep being pushed up, very slowly
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 slowly shift far apart, sideways
   • They crash together into mountains
   • They stay exactly where they are
   • They swap sides of the fault within one lifetime
4. 4.

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

   • 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
   • Disagree: it lived in fresh water; the lands were joined then
5. 5.

   “Cross-section, not to scale:” Noah's cousin says the oldest seafloor is found at the mid-ocean ridges. Which response is best?

   • Disagree: the youngest is at ridges; it gets older outward
   • Disagree: seafloor is one age everywhere
   • Agree: ridges are where plates crash
   • Agree: ridges are where the oldest rock slowly piles up in heaps
6. 6.

   Map of South America and Africa fitted together along their coasts. Which set of clues best supports the idea that South America and Africa were once joined, by Pia's judgment?

   • Both continents have tall mountains
   • Both continents have deserts today
   • Animals today can still travel easily between the two of them
   • Matching coastlines, fossils and rock layers
7. 7.

   “Cross-section, not to scale:” Ren looks for evidence that the seafloor spreads. Which observation is the best evidence?

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

   Map of a coast with the sea floor offshore unlabeled. Which clue tells Tala that a convergent boundary lies just off a coast?

   • A deep trench with a chain of volcanoes beside it
   • A straight fault with sideways offsets
   • Flat, quiet seafloor with no earthquakes or volcanoes nearby
   • A ridge with brand-new seafloor
9. 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?

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

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

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