Put rock layers in order

Grade 9 Science Worksheet - Challenge Me

Circle the best answer.

1. 1.

   On card Z, which pair of events can Ari NOT put in order?

   • Granite G and Unit 4: pebbles inside Unit 4 say nothing about order
   • Dike K and dike M: both are younger than Unit 5 but never touch
   • Granite G and dike K: they never touch, so nothing links them
   • Unit 2 and Unit 4: an erosion surface lies between them
2. 2.

   On card Y, Bo reads about basalt sheet B and its dike. Which statement is supported?

   • B came after Unit 4, since its dike reaches up to Unit 4
   • Unit 4 formed before B, since Unit 4 holds basalt pebbles
   • Units 2 and 3 first; B and its dike next; Unit 4 last
   • B flowed over Unit 2, and then Unit 3 was laid down on it

3. Read this first

   Column Q (made up), bottom to top

   Unit 1; Unit 2 with an ash bed dated 320 Ma; Unit 3; an erosion surface; Unit 4 with an ash bed dated 250 Ma. Dike D cuts Units 1 to 3, ends at the erosion surface, and is dated 280 Ma.

4. 3.

   Using the dated ash beds and dike on card Q, what is the most time Esme can say is missing at the erosion surface?

   • No time is missing: an erosion surface just marks a pause
   • Exactly 70 million years, from the ash beds
   • 30 million years, from the 320 Ma ash to the 280 Ma dike
   • At most 70 million years, from the 320 Ma ash to the 250 Ma ash
5. 4.

   Unit 3 limestone is 40 m thick; Unit 4 siltstone is 10 m thick. Jun's friend says Unit 3 is 40 m thick and Unit 4 is 10 m thick, so Unit 3 is four times older. Which reply is best?

   • Wrong: Unit 4 is on top, so it must be four times older
   • Wrong: just dikes and faults can be compared by thickness
   • Correct: thicker layers take longer, so Unit 3 is four times older
   • Thickness shows sediment amount, not time; rates and gaps vary

6. 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. 5.

   A conglomerate holds limestone pebbles with fossil Q; its sandy matrix holds fossil S. Luz says it formed in slices 2 to 3. Best reply?

   • No: it formed in slices 2 to 5, where either fossil lived
   • Yes: fossils found inside a rock date that whole rock
   • No: Q is in older pebbles; S in the matrix gives slice 5
   • Yes: Q is the older fossil, so it sets the rock's age
8. 6.

   Noah finds basalt sheet B between layer m (Q and R, below) and layer n (S, above). It baked both. When could B have formed?

   • Slice 4 exactly, halfway between the layers
   • Slice 5 or later, after layer n formed
   • Slice 3, the age of layer m
   • Between slices 3 and 5, as the layers surround it
9. 7.

   Granite G, dated 1,700 Ma, holds chunks of schist. Sandstone about 510 Ma lies on the eroded granite. What can Pia say about the schist?

   • The schist is younger than 510 Ma, since the sandstone covers it
   • The schist is older than 1,700 Ma, as its chunks sit inside
   • The schist is exactly 1,700 Ma, the age of the granite
   • The schist is younger than 1,700 Ma, since the granite surrounds it
10. 8.

    Layer X is older than layer Y at two sites. Ren's friend says X formed exactly 5 million years before Y. What would test that?

    • Radiometric dates from ash or igneous rock around each layer
    • Measure the thickness of rock between X and Y
    • Check that X lies below Y at a third distant site
    • Count the fossils in each layer and compare the counts

11. 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.

12. 9.

    Two cliffs each have a limestone. Cliff 1's holds fossil Q; Cliff 2's holds fossil S. Tala says they match. Does the evidence support that?

    • Cannot tell: fossils cannot be used to date limestone
    • Yes: both limestones lie at the same height in their cliffs
    • No: Q marks slices 2 to 3 and S marks slice 5
    • Yes: the same rock type means the same age everywhere
13. 10.

    Zee claims the erosion surface under Unit 4 formed between 190 Ma and 160 Ma. Which new finding would most weaken the claim?

    • A re-dating of dike D to 150 Ma, younger than the ash
    • A fossil in Unit 4 that also lived during Unit 3 times
    • Another dike like D found in Unit 2
    • A new date of 185 Ma for dike D