Did any individual pom poms change color yes no X If no then why ... - Free Printable

Let’s go step by step through each question on the worksheet. I’ll solve them one at a time, carefully checking my reasoning before giving the final answer.

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Question 1a: Two different layers of sedimentary rocks are shown in the diagram. Layer A is located above layer B. Which layer is older? Explain your answer.

In geology, there’s a basic rule called the Law of Superposition: In undisturbed rock layers, the oldest layers are at the bottom, and younger layers are deposited on top.

Here, Layer A is *above* Layer B → so Layer B must be older.

✔ Final Answer for 1a: Layer B is older because it is underneath Layer A, and according to the Law of Superposition, lower layers are older than upper layers in undisturbed sequences.

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Question 1b: The figure below shows three types of fossils found in different rock layers (labeled 1, 2, and 3). Based on their positions, which fossil is likely the oldest? Why?

Again, using the Law of Superposition — the deeper the layer, the older it is.

Fossil in layer 3 is deepest → oldest
Fossil in layer 2 is middle → medium age
Fossil in layer 1 is shallowest → youngest

So, fossil in layer 3 is oldest.

✔ Final Answer for 1b: The fossil in layer 3 is likely the oldest because it is in the lowest (deepest) rock layer, meaning it was deposited first.

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Question 1c: Scientists use relative dating to determine the order of events in Earth’s history without knowing exact ages. What does “relative” mean in this context?

“Relative” here means comparing things to each other — not measuring with numbers or clocks.

Example: If you say “I am taller than my brother,” that’s relative — you’re not saying how many centimeters tall you are, just who is taller.

In geology, relative dating tells us which event happened before another — like which rock layer formed first — but not exactly when (like “65 million years ago”).

✔ Final Answer for 1c: “Relative” means comparing the age of one thing to another — telling us what came first or last, but not giving an exact number of years.

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Question 1d: How can scientists tell if two rock layers from different locations were formed at about the same time?

Scientists look for clues like:

- Same type of fossils in both layers → suggests same time period (fossils change over time)
- Similar rock types and structures
- Matching patterns in magnetic minerals or volcanic ash layers

This is called correlation — matching up rock layers across distances.

✔ Final Answer for 1d: Scientists compare fossils, rock types, and special markers (like volcanic ash) in the layers. If they match, the layers probably formed around the same time.

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Question 1e: Absolute dating gives the actual age of a rock or fossil in years. Name one method used for absolute dating and explain briefly how it works.

One common method is radiometric dating, especially carbon-14 dating for once-living things up to ~50,000 years old.

How it works: Living things take in carbon-14 while alive. When they die, they stop taking it in, and the carbon-14 decays at a known rate. By measuring how much is left, scientists calculate how long ago the organism died.

For older rocks, they use other isotopes like uranium-lead or potassium-argon.

✔ Final Answer for 1e: Radiometric dating (like carbon-14 dating) measures how much radioactive material is left in a sample. Since we know how fast it decays, we can calculate how old the sample is.

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Question 1f: Why might some rock layers be missing in a sequence even though no erosion occurred after deposition?

Even without erosion, layers can be missing due to:

- Non-deposition: Sometimes, no sediment was deposited during a certain time period — maybe the area was dry land instead of underwater.
- Unconformities: Gaps in the rock record caused by pauses in deposition or later removal (but question says “no erosion after deposition,” so focus on non-deposition).

Also, tectonic activity could lift the area so no new sediment settles — creating a gap.

✔ Final Answer for 1f: Some layers may be missing because no sediment was deposited during that time — for example, if the area was exposed as land instead of being under water where sediment usually builds up.

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Question 1g: You find a fossil of a fish in a rock layer. Later, you find a similar fish fossil in a different location. Can you assume these two fossils are the same age? Why or why not?

Not necessarily! Just because the fossils look similar doesn’t mean they’re from the same time.

Fish species can live for millions of years — so similar-looking fish could exist in different eras.

To be sure, scientists need to check:

- The rock layers’ position (using superposition)
- Other fossils nearby (index fossils help date layers)
- Radiometric dates if possible

✔ Final Answer for 1g: No, you cannot assume they are the same age just because they look similar. Similar species can exist over long periods. You need to check the rock layers and other evidence to confirm their ages.

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Question 1h: What would happen to the accuracy of relative dating if all rock layers had been turned upside down by tectonic forces?

If layers are flipped, then the usual rule (bottom = oldest) no longer applies directly.

You’d have to look for other clues:

- Fossil succession (which fossils appear together)
- Cross-cutting relationships (faults or intrusions cutting through layers)
- Sedimentary structures (like ripple marks or mud cracks that show original orientation)

Without those, relative dating based only on layer position would give wrong results.

✔ Final Answer for 1h: If layers are upside down, relative dating based on position alone would be inaccurate. Scientists would need to use other clues like fossils or rock features to figure out the true order.

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Now, compiling all answers clearly:

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Final Answer:

1a: Layer B is older because it is underneath Layer A, and according to the Law of Superposition, lower layers are older than upper layers in undisturbed sequences.

1b: The fossil in layer 3 is likely the oldest because it is in the lowest (deepest) rock layer, meaning it was deposited first.

1c: “Relative” means comparing the age of one thing to another — telling us what came first or last, but not giving an exact number of years.

1d: Scientists compare fossils, rock types, and special markers (like volcanic ash) in the layers. If they match, the layers probably formed around the same time.

1e: Radiometric dating (like carbon-14 dating) measures how much radioactive material is left in a sample. Since we know how fast it decays, we can calculate how old the sample is.

1f: Some layers may be missing because no sediment was deposited during that time — for example, if the area was exposed as land instead of being under water where sediment usually builds up.

1g: No, you cannot assume they are the same age just because they look similar. Similar species can exist over long periods. You need to check the rock layers and other evidence to confirm their ages.

1h: If layers are upside down, relative dating based on position alone would be inaccurate. Scientists would need to use other clues like fossils or rock features to figure out the true order.