Question

multiple choice 1 point
which of the following is true about the rock layers in the picture above?

• the rock layers originally formed in the same position they are in now.
• the rock layers are most likely less than a few thousand years old due to their color.
• the rock layers originally formed flat, horizontal layers.
• the rock layers were likely formed from a glaciers deposited rocks

Explanation:

To solve this, we analyze each option based on geological principles (stratigraphy, rock formation):

1. Option 1 Analysis: Rock layers (strata) are originally deposited horizontally (Principle of Original Horizontality). If they’re tilted, tectonic forces (like folding/faulting) acted after deposition. So layers aren’t in their original horizontal state—this is false.
2. Option 2 Analysis: Rock layer color alone doesn’t determine age (age is determined by radiometric dating, fossil content, or stratigraphic position). So “much older due to color” is false.
3. Option 3 Analysis: The Principle of Original Horizontality states sedimentary rocks are deposited horizontally. Tilted layers (like in the image) form when horizontal layers are later deformed (e.g., by tectonic activity). This matches geological theory—this is true.
4. Option 4 Analysis: Sedimentary rock layers form from sediment accumulation (not “melting from a glacier’s pressure”). Glacial pressure causes metamorphism, not sedimentary layering—this is false.

Analyze each option using geological principles (Original Horizontality, rock age determination, sedimentary layer formation). Only the third option aligns with how tilted sedimentary layers form (horizontal deposition followed by deformation).

Answer:

The rock layers originally formed flat, horizontal layers (and were later tilted by tectonic forces) (the option stating "The rock layers originally formed flat, horizontal layers").