Reading rock layers and the history of life

Grade 6 Science Worksheet - Challenge Me

Circle the best answer.

1. 1.

   Two rock columns, not to scale. Two sites far apart both have a shale layer with the same index trilobite. Which layer at Site 2 matches the trilobite shale at Site 1, by Esme's matching?

   • The coal on top, since it is the youngest layer there
   • Whichever layer is thickest
   • The conglomerate at the bottom
   • The shale with the same trilobite
2. 2.

   Luz's friend says early people and dinosaurs lived at the same time. Which response is best?

   • Agree: cartoons and movies often show them living together
   • Disagree: those dinosaurs were extinct about 66 million years before people
   • Disagree: dinosaurs lived after people
   • Agree: their fossils are in the same layers
3. 3.

   A post says the thick rock layers in a canyon wall formed in just a few years. Milo checks it. Which response is best?

   • Disagree: the layers built up over millions of years
   • Agree: sand piles up meters each year in canyons like this
   • Agree: thick layers like these can form in one rainy season
   • Disagree: the top layers are the oldest
4. 4.

   Noah's cousin says any fossil can tell the exact age of a rock. Which response is best?

   • Agree: each fossil shows its own year
   • Disagree: index fossils narrow the age; radioactive dating gives numbers
   • Disagree: fossils show nothing about age
   • Agree: bigger fossils are older, so their size tells the age
5. 5.

   Cross-section, not to scale. Layers A (bottom), B and C are cut by a dike. Layer D lies on top and is not cut. Which order of events, oldest first, does Pia choose?

   • Layers A, B, C, then the dike, then D
   • Layers A, B, C, D, then the dike
   • Layer D, then C, B, A, then the dike
   • The dike first, then layers A, B and C, then layer D
6. 6.

   A fault cuts layers A to C. Layer B holds an index fossil from about 300 million years ago. What can Ren say about the fault?

   • It is exactly 300 million years old
   • It is younger than about 300 million years
   • It formed this century
   • It is older than 300 million years, since it cuts deep
7. 7.

   The bottom layer has ichthyosaurs (sea reptiles) and ammonites, the middle layer has ammonites but no ichthyosaurs, and the top layer has neither. Which story fits, by Tala's reading?

   • Ammonites became extinct first; ichthyosaurs lasted much longer
   • Both groups still live in those seas
   • Ichthyosaurs became extinct first; ammonites lasted longer
   • The three layers formed in one year

8. Read this first

   A 24-hour clock face for Earth's history

   Midnight at the start is Earth forming; the next midnight is today.

9. 8.

   Squeeze Earth's 4.5 billion years into one 24-hour day. When does Zee find that dinosaurs (other than birds) became extinct?

   • At about noon
   • At about 6 p.m.
   • Seconds before midnight, alongside the first people
   • At about 11:39 p.m.
10. 9.

    On the same 24-hour day, when do modern people appear, about 300,000 years ago? Ari works it out.

    • At about noon, halfway through
    • About 6 seconds before midnight
    • In the very first hour, just as the Earth formed
    • At about 11:39 p.m., with the dinosaurs
11. 10.

    On the 24-hour day, animals with hard shells appear around 9 p.m., about 539 million years ago. What does that show Bo about life on Earth?

    • Shelled animals were there from the very start of the day
    • Most of Earth's history passed before shelled animals
    • People appeared right after them
    • Life has been the same since midnight