Which of the following is NOT true of a sedimentary facies?

• A. Fossil remnants will be consistent throughout the facies
• B. Facies can vary laterally
• C. They reflect environment of deposition
• D. They can show changes in grain size

Answer: (C)

Sedimentary facies are bodies of rock that record a particular depositional environment, and their characteristics can vary within the same facies as conditions change over time or across space. Fossil content isn’t uniformly identical throughout a single facies because microhabitats, layering, and time averaging can yield different fossil assemblages in different parts of the same depositional setting. That makes the statement about fossil remnants being consistent throughout the facies not necessarily true.

The other ideas fit what facies do: they can vary laterally across space as environments shift or grade into one another; they reflect the environment in which they were deposited; and they can show changes in grain size as energy conditions or sediment supply change.