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 2,500 km
   • About 250 km
   • About 25 km
   • No wider; continents are fixed
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 stay exactly where they are
   • They slowly shift far apart, sideways
   • They swap sides of the fault within one lifetime
   • They crash together into mountains
3. 3.

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

   • Disagree: plates do not move
   • 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
4. 4.

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

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

   • 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
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
   • The ridge sits mid-ocean, so its rock must be the oldest there
   • Ridges have no earthquakes
   • 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?

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

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

   • 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
   • Matching fossils and rocks lining up across the joins
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 that stay fixed
   • Plates riding on slowly moving mantle rock
   • Earthquakes shaking the crust
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 transform fault
    • Mountains at a convergent boundary
    • A ridge at a divergent boundary
    • A trench from plates pulling apart