Question

a geologist finds some tilted sedimentary rock layers. which conclusion can the geologist draw by looking at the rock layers? ○ their absolute age is 600 million years. ○ they were tilted before they were deposited. ○ they were originally deposited horizontally. ○ the youngest layer was originally deposited as the bottom layer.

Explanation:

• For the first option: Absolute age of rock layers can't be determined just by looking at tilted sedimentary layers; radiometric dating or other methods are needed. So this is incorrect.
• For the second option: Sedimentary rocks are deposited in horizontal layers first, then tilting occurs later. So they can't be tilted before deposition. Incorrect.
• For the third option: The principle of original horizontality states that sedimentary rock layers are originally deposited horizontally, and tilting happens after deposition. So this is a valid conclusion.
• For the fourth option: The law of superposition says the youngest layer is on top, oldest at the bottom originally. So this is incorrect.

Answer:

C. They were originally deposited horizontally. (Here we assume the options are labeled as A, B, C, D with A being "Their absolute age is 600 million years", B being "They were tilted before they were deposited", C being "They were originally deposited horizontally", D being "The youngest layer was originally deposited as the bottom layer")