What would be the proper stratigraphic reference for the Kaibab limestone formation deposited during the end of the Permian?

• A. Kaibab Limestone (Early Permian)
• B. Kaibab Limestone (Late Permian)
• C. Kaibab Formation (Late Permian)
• D. Kaibab Limestone (Mid Permian)

Answer: (B)

In stratigraphy, you reference a rock unit by its formal name and the time interval during which it was deposited. For the Kaibab rocks, the conventional reference is Kaibab Limestone with the age tied to the Late Permian, since this carbonate unit was laid down toward the end of the Permian period, just before the Triassic. That makes the pairing Kaibab Limestone, Late Permian the most accurate descriptor.

The other options either use an incorrect time subdivision (early or mid Permian) or switch to Kaibab Formation, which isn’t the standard nomenclature used for this unit.