Despite its usefulness, radiocarbon dating has a number of limitations. First, the older the object, the less carbon-14 there is to measure. Radiocarbon dating is therefore limited to objects that are younger than 50,000 to 60,000 years or so.

What method is used to date rocks older than 100 000 years?

Radiometric datingDating methodMaterial datedAge range datedLuminescenceTephra, loess, lake sedimentsUp to 100,000 years agoFission trackTephra10,000 to 400 million years agoPotassium-40 to argon-40Volcanic rocks20,000 to 4.5 billion years agoUranium-238 to lead-206Volcanic rocks1 million to 4.5 billion years ago1 more row•20 May 2011