Question

Rock layer diagram. 5 layers on each side of a fault. Layers 1 to 5, top to bottom on the left, layers 6 to 10, top to bottom on the right. The following pairs are the same: 1 and 8; 2 and 9; 3 and 6; 4 and 7. Layers 5 and 10 do not have matches.
Which statements about this diagram are true? Check all that apply.

Layers 5 and 7 are the same age.
Faulting created the differences in layers.
Erosion created the differences in layers.
Layers 2 and 9 are the same age.
The organisms in 1 and 8 lived tens of millions of years apart.

Answer 1

True:
- Faulting created the differences in layers.
- Erosion created the differences in layers.
- Layers 2 and 9 are the same age.

Why:
- The given matches (1=8, 2=9, 3=6, 4=7) show the rock units on opposite sides were once continuous but were displaced by a fault — so faulting produced the offset differences.
- The unmatched layers (5 and 10) indicate material is missing on one side (or the other) and therefore erosion (or nondeposition) also played a role in the differences.
- 2 and 9 are listed as the same layer, so they are the same age.

False:
- Layers 5 and 7 are the same age — no: 7 matches layer 4, not 5.
- The organisms in 1 and 8 lived tens of millions of years apart — no: 1 and 8 are the same layer and thus the same age.