Question

test corrections change over time csa
chp 13.1
using the figure above, which of the following is a correct analysis? (mark all that apply)
(the shapes are different fossils in the different rock layers)

• rock layer g is the youngest rock layer of the sample.
• square fossil is older than triangle fossil.
• circle fossil is older than square fossil.
• circle fossil is older than star fossil but younger than triangle fossil.
• rock layer b is the oldest layer with fossils.
• square fossil is older than triangle fossil but younger than star fossil.

Explanation:

To solve this, we analyze the rock layers (younger layers are on top, older at the bottom) and fossil positions:

1. Analyze "Rock Layer G is the youngest..."

Rock layers are stacked with the top layer (G) being the youngest (since sedimentary layers form over time, top = youngest, bottom = oldest). Correct.

2. Analyze "Square fossil is older than triangle fossil"

Square fossil is in Layer C; triangle fossil is in Layer B. Layer C is above Layer B (so Layer C is younger than B). Thus, square fossil (Layer C) is younger than triangle fossil (Layer B). Incorrect.

3. Analyze "Circle fossil is older than square fossil"

Circle fossil is in Layer E; square fossil is in Layer C. Layer E is above Layer C (Layer E is younger than C). Thus, circle fossil (Layer E) is younger than square fossil (Layer C). Incorrect.

4. Analyze "Circle fossil is older than star fossil but younger than triangle fossil"

• Star fossil: Layer G (youngest layer).
• Circle fossil: Layer E (above C, B, A; below F, G).
• Triangle fossil: Layer B (below C, E, F, G; above A).

Layer order (oldest to youngest): A → B → C → D → E → F → G.
So: Triangle (B) < Circle (E) < Star (G) (since older layers are lower). Thus, Circle is older than Star (G is younger than E) and younger than Triangle (B is older than E). Correct.

5. Analyze "Rock Layer B is the oldest layer with fossils"

Layer A is the bottom layer (oldest) but has no fossil (per the diagram). Layer B is the first layer with a fossil (triangle). So Layer B is the oldest layer with fossils. Correct.

6. Analyze "Square fossil is older than triangle fossil but younger than star fossil"

• Square (Layer C) vs Triangle (Layer B): Layer C is above B (so square is younger than triangle).
• Square (Layer C) vs Star (Layer G): Layer C is below G (so square is older than star).

This statement claims "older than triangle" (false) and "younger than star" (true) → overall Incorrect.

Final Correct Options:

• Rock Layer G is the youngest rock layer of the sample.
• Circle fossil is older than star fossil but younger than triangle fossil.
• Rock Layer B is the oldest layer with fossils.

Answer:

• Rock Layer G is the youngest rock layer of the sample.
• Circle fossil is older than star fossil but younger than triangle fossil.
• Rock Layer B is the oldest layer with fossils.