Put rock layers in order

Grade 9 Science Worksheet - Building Confidence

Circle the best answer.

1. 1.

   On card K, Ari compares Unit 3 with dike D. Which is older, and why?

   • Dike D, because it reaches deeper than Unit 3 does
   • Unit 3, because dike D cuts through it
   • Dike D, because it is basalt and Unit 3 is limestone
   • Neither; one cannot be older without a date
2. 2.

   On card G, Esme wants the oldest rock. Granite B holds chunks of Unit 1. Which is oldest?

   • Unit 1: bottom layer, with chunks inside the granite
   • Granite B: it cuts through the lowest units of the cliff
   • Unit 4: it is the top layer of the whole cliff
   • Unit 3: it holds pebbles of the granite itself
3. 3.

   Fault F on card K offsets dike D and Unit 4. What does Kira learn about Unit 4 and the fault?

   • Unit 4 came first, and fault F broke it later
   • Unit 4 is the youngest event, since it is the top layer
   • Both formed at the same moment
   • Fault F came first, and Unit 4 was laid over it
4. 4.

   “(made up), bottom to top:” On card T, Luz asks which is older, the basalt sheet or Unit 3. Heat baked Unit 3 above the sheet.

   • The basalt, because it lies below Unit 3 in the stack
   • The basalt, because it is much harder rock than Unit 3
   • Unit 3: the basalt baked it, so the basalt came in later
   • Same age, because they touch along one flat line

5. Read this first

   Table, Fossil ranges (made up), with columns Fossil, Time slices lived (1 oldest, 6 youngest), Where found

   P, 1 to 4, worldwide; Q, 2 to 3, one basin only; R, 3 to 5, worldwide; S, 5, worldwide. Note: A time slice is one equal span of time.

6. 5.

   A layer holds fossils Q and R. In which time slice did Milo's layer form?

   • Slices 2 to 5, every slice either one lived
   • Slice 3, the only slice when both lived
   • Slice 5, when R last lived
   • Slice 2, when Q first appeared
7. 6.

   Noah needs one fossil to match rocks on different continents. Which is the best index fossil?

   • P: it lived the longest, so it fits the most rock
   • Q: it lived a short time, though in one basin alone
   • R: it is worldwide, though it lived three slices
   • S: it lived for one slice and is found worldwide
8. 7.

   A layer holds only fossil P. What can Pia safely say about its age?

   • Its age is unknown, since a fossil cannot narrow time whatsoever
   • It formed in slice 4, the last slice P lived
   • It formed sometime in slices 1 to 4; P alone cannot say which
   • It formed in slice 1, when P first appeared
9. 8.

   On card H, Ren studies the wavy surface between Unit C and flat Unit D. What does it show?

   • Time is missing: tilted layers eroded before D formed
   • D is older, because it stayed flat and undisturbed
   • The layers were laid down in one single event
   • Nothing is missing; C simply ends and D starts

10. NPS (Grand Canyon)

    The Layered Paleozoic Rocks are about 510 Ma; the Vishnu Basement Rocks are about 1.75 billion years (1,750 Ma). At the Great Unconformity they touch directly.

11. 9.

    At one Grand Canyon spot, 510 million-year-old (510 Ma) sandstone rests on 1.75 billion-year-old schist. What does Tala infer?

    • About 510 million years are missing from the record there
    • The sandstone is older, because it sits on top of the schist
    • Nothing is missing there, because the two rocks touch directly
    • About 1.2 billion years of rock record are missing there
12. 10.

    Zee sees flat layers, but the boundary between two of them is rough and cuts into the lower layer. What does it mean?

    • Erosion cut the lower layer before the upper layer was laid down
    • The upper layer is older, since it is pressed into the lower
    • Both layers formed at the same moment
    • It is a normal boundary, so no time is missing