Uranium-234–uranium-238 dating, method of age determination that makes use of the radioactive decay of uranium-238 to uranium-234; the method can be used for dating of sediments from either a marine or a playa lake environment.
Which uranium isotope is used in dating?
Uranium–lead radiometric dating involves using uranium-235 or uranium-238 to date a substances absolute age. This scheme has been refined to the point that the error margin in dates of rocks can be as low as less than two million years in two-and-a-half billion years.
Why is uranium 238 good for dating the age of the Earth?
The long half-life of uranium-238 makes it possible to date only the oldest rocks. Although the half-life of rubidium-87 is even longer than uranium-238 (49 billion years or 10 times the age of the earth), it is useful because it can be found in almost all igneous rocks.