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?

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

   On card H, Bo asks which came first, the tilting of Units A to C or the laying down of flat Unit D?

   • Unit D came first, then everything was tilted after it
   • Tilting came first; D was laid on the eroded edges
   • Units A to C were tilted after D had covered them
   • They happened together, as Unit D slowly formed
3. 3.

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

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

   On card S, Jun decides whether the basalt sheet is older or younger than Unit 3. Which answer fits the evidence?

   • Younger: it baked Unit 2, so it flowed in after Unit 3
   • Neither can be known without a radiometric date
   • Younger: Unit 3 holds basalt pebbles, so Unit 3 came first
   • Older: Unit 3 holds basalt pebbles, so basalt came first
5. 5.

   “(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.

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

6. 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.

7. 6.

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

   • Slice 3, the only slice when both lived
   • Slice 5, when R last lived
   • Slice 2, when Q first appeared
   • Slices 2 to 5, every slice either one lived
8. 7.

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

   • S: it lived for one slice and is found worldwide
   • Q: it lived a short time, though in one basin alone
   • P: it lived the longest, so it fits the most rock
   • R: it is worldwide, though it lived three slices
9. 8.

   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 sometime in slices 1 to 4; P alone cannot say which
   • It formed in slice 1, when P first appeared
   • It formed in slice 4, the last slice P lived
10. 9.

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

    • 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
    • Time is missing: tilted layers eroded before D formed
11. 10.

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

    • It is a normal boundary, so no time is missing
    • 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