Question

Which layer of rock is the oldest?
1) 1
2) 2
3) 3
4) 4

Answer 1

The oldest layer of rock in an undisturbed sedimentary sequence is typically at the bottom, but factors like tilting, folding, and the presence of fossils can complicate determining relative ages.

Step-by-step explanation:

In stratigraphy, the principle of superposition states that in any sequence of undisturbed sedimentary rocks, the oldest rocks are at the bottom, with younger rocks on top. Without additional information, it is generally true that rock layer 1 would be the oldest if the layers are numbered from bottom to top.

However, if the rock layers are tilted or folded, the relative ages might be more complex to determine and can involve studying the direction of the tilting and the nature of the contacts between the layers. Geologic structures such as folds, which often feature in such tilted sequences, can also indicate the forces that have acted upon the sequence.