The Kaibab Limestone deposition is associated with which geologic age?

• A. Early Permian
• B. Early Jurassic
• C. Late Triassic
• D. Late Permian

Answer: (D)

In sedimentary geology, the age of a rock unit is read from its place in the sequence and the fossils it contains. The Kaibab Limestone sits in the Permian part of the Grand Canyon stratigraphy, lying beneath Triassic rocks and above older Mississippian–Pennsylvanian units. The fossil assemblage found in the Kaibab (shallow marine faunas typical of the late Paleozoic) and its position directly before Triassic deposits indicate it formed toward the end of the Permian. So, deposition is best placed in the Late Permian.