Question

sediment that settles out of water usually forms horizontal layers. which of the following describes a characteristic of the bottom layer? a oldest b lightest c youngest d darkest

Explanation:

In sedimentary layers formed by settling out of water, the principle of superposition applies (a key concept in geology, a subfield of Natural Science). Older sediments settle first and form the bottom layers, while younger sediments are deposited on top. So the bottom layer is the oldest. Option b is incorrect as heavier (not lightest) sediments tend to settle first. Option c is wrong because the bottom layer is oldest, not youngest. Option d isn't a consistent characteristic related to the order of sedimentation.

Answer:

a. oldest