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

   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 crash together into mountains
   • They stay exactly where they are
   • They slowly shift far apart, sideways
   • They swap sides of the fault within one lifetime
3. 3.

   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: the continents have stayed right where they are today, so it swam
   • Agree: reptiles can swim great distances
4. 4.

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

   • Agree: plates surf fast on liquid lava
   • Agree: you can watch coastlines move from one year to the next
   • Disagree: plates move a few centimeters a year
   • Disagree: plates do not move
5. 5.

   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?

   • Matching coastlines, fossils and rock layers
   • Both continents have deserts today
   • Animals today can still travel easily between the two of them
   • Both continents have tall mountains
6. 6.

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

   • Rock gets older moving away from the ridge on both sides
   • Ridges have no earthquakes
   • The ridge sits mid-ocean, so its rock must be the oldest there
   • The ocean is deepest near the coasts
7. 7.

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

   • A ridge with brand-new seafloor
   • A straight fault with sideways offsets
   • A deep trench with a chain of volcanoes beside it
   • Flat, quiet seafloor with no earthquakes or volcanoes nearby
8. 8.

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

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

   • Continents floating along on top of a liquid lava ocean
   • Plates riding on slowly moving mantle rock
   • Earthquakes shaking the crust
   • Plates that stay fixed
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 trench from plates pulling apart
    • Mountains at a convergent boundary
    • A ridge at a divergent boundary
    • A transform fault