# Disadvantages of uranium lead dating

Most rocks contain *uranium*, allowing *uranium*-*lead* and similar methods to date them.Other elements used for **dating**, such as rubidium, occur in some minerals but not others, restricting usefulness.

This leaves out important information which would tell you how precise is the **dating** result.

Carbon-14 *dating* has an interesting limitation in that the ratio of regular carbon to carbon-14 in the air is not constant and therefore any date must be calibrated using dendrochronology.

Another limitation is that carbon-14 can only tell you when something was last alive, not when it was used.

A limitation with all forms of radiometric **dating** is that they depend on the presence of certain elements in the substance to be dated.

This is consistent with the assumption that each decay event is independent and its chance does not vary over time.

The solution is: where is the half-life of the element, is the time expired since the sample contained the initial number atoms of the nuclide, and is the remaining amount of the nuclide.One problem is that potassium is also highly mobile and may move into older rocks.This depends on the decay of **uranium**-237 and **uranium**-238 to isotopes of **lead**.Symbolically, the process of radioactive decay can be expressed by the following differential equation, where N is the quantity of decaying nuclei and k is a positive number called the exponential decay constant.The meaning of this equation is that the rate of change of the number of nuclei over time is proportional only to the number of nuclei.We can measure directly, for example by using a radiation detector, and obtain a good estimate of by analyzing the chemical composition of the sample.