Reading rock layers and the history of life

Grade 6 Science Worksheet

Circle the best answer.

1. 1.

   A band of igneous rock, called a dike, cuts straight up through layers A to D. How old is the dike compared with the layers, by Bo's reasoning?

   • Younger than all four layers
   • The same age as layer D
   • Older than the top layer
   • Older than all four layers
2. 2.

   A fault breaks through layers A, B and C, but not through layer D lying flat on top. Which statement does Esme pick?

   • The fault is older than layer A
   • The fault happened after C but before D formed
   • The fault happened after layer D had formed on top
   • Layer D is the oldest layer

3. Read this first

   Table, Fossil kinds, with columns Kind, How long it lived and Where found

   W, a short span, worldwide; X, a very long span, worldwide; Y, a short span, one small area; Z, a very long span, one small area.

4. 3.

   Kira is choosing a fossil to help date rock layers around the world. Which kind makes the best index fossil?

   • A kind that lived for a very long time
   • A kind found in one small area
   • A kind that lived a short time but spread widely
   • Whichever fossil is the biggest
5. 4.

   Trilobite species W, lived for a short span, found worldwide. An example trilobite, species W, lived for a short span long ago and is found worldwide. What does a layer holding species W tell Luz?

   • The layer formed during that short span
   • The layer is the oldest on Earth
   • The layer formed last century
   • Nothing, since fossils cannot date rock
6. 5.

   Ammonite, a coiled shell; lived in the Mesozoic Era; extinct about 66 million years ago. Ammonites lived in Mesozoic seas and became extinct about 66 million years ago. A layer holds ammonite fossils. What does Milo conclude?

   • The layer formed in the Cenozoic Era
   • The layer formed after people appeared
   • The layer formed recently, since shells are common
   • The layer formed in the Mesozoic Era
7. 6.

   Fossils of ferns that need warm weather are found in rock in Antarctica. What best explains this, by Pia's thinking?

   • Antarctica's climate has stayed the same
   • Antarctica once had a much warmer climate
   • Ferns grow on the ice there today
   • Wind blew the ferns there recently
8. 7.

   Layer C has fish fossils. Layer B, just above it, has land plant fossils. The layers are undisturbed. What changed at this place, says Ren?

   • Nothing changed there
   • The plants are older than the fish
   • The area went from water to land
   • The area went from land to water

9. Use this

   Table (example rock column), Fossils by layer (example), with columns Group and Layers found (1 = bottom), layers numbered 1 (bottom) to 6 (top): trilobites in layers 1 to 3; ammonites in layers 4 and 5; mammals in layers 5 and 6.

10. 8.

    Tala's table shows which fossil groups appear in six layers, numbered from the bottom. Which group became extinct earliest?

    • Trilobites
    • Mammals
    • No group; each is still around
    • Ammonites
11. 9.

    Using the same table, Zee looks for the group found in the youngest layers. Which group is it?

    • Ammonites
    • Mammals
    • Trilobites
    • The three groups equally
12. 10.

    A fossil shows up in many layers, then is missing from every layer above. What does that suggest to Ari?

    • It moved up into a higher layer later
    • The upper layers are older
    • That kind of life became extinct
    • It is still alive everywhere today