Britannica
Sources used in this answer
Why are Mammoth Cave sediments more than two million years old?
Created from Britannica articles
using AI.
AI can make mistakes, so verify using Britannica articles.
cave
Stalactites and stalagmites in the Queen's Chamber, Carlsbad Caverns National Park, southeastern New Mexico.
The age of sediments in Mammoth Cave is determined through the study of paleomagnetism. These sediments contain iron-bearing magnetic particles that record the orientation of the Earth’s magnetic field at the time of their deposition.1
By measuring this paleomagnetic record and correlating it with the established geomagnetic polarity time scale, researchers have ascertained that the sediments in the highest-elevation passages of the cave system are at least 2,000,000 years old. This method allows geologists to date the long history of cave development, as these ancient deposits provide a timeline for when the passages were formed and subsequently abandoned by surface streams.21