# Question: How far back can uranium lead dating go?

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Uranium–lead dating, abbreviated U–Pb dating, is one of the oldest and most refined of the radiometric dating schemes. It can be used to date rocks that formed and crystallised from about 1 million years to over 4.5 billion years ago with routine precisions in the 0.1–1 percent range.

## How old can uranium-238 date?

4.5 billion years Uranium 238 has a half life of 4.5 billion years. Uranium can be used to date the age of the earth. If 50% of pure uranium is left in a sample the sample is assumed to be 4.5 billion years old.

## How far back can Uranium-235 date?

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.

## How accurate is uranium lead dating?

In a paper published this week in Science, geochemist Roland Mundil of the Berkeley Geochronology Center (BGC) and his colleagues at BGC and UC Berkeley report that uranium/lead (U/Pb) dating can be extremely accurate - to within 250,000 years - but only if the zircons from volcanic ash used in the analysis are

## How is uranium used in dating?

As its name suggests, uranium-series dating uses the radioactive decay of uranium to calculate an age. When uranium decays, it goes through a series of decays until it eventually reaches a stable isotope. So, for example, uranium 238 will decay to uranium 234, which will decay to thorium 230.

## Which is more radioactive U-235 or U-238?

The nucleus of the U-235 atom contains 92 protons and 143 neutrons, giving an atomic mass of 235 units. The U-238 nucleus also has 92 protons but has 146 neutrons – three more than U-235 – and therefore has a mass of 238 units.

## Why Uranium-235 is unstable?

Although they are tiny, atoms have a large amount of energy holding their nuclei together. During fission, U-235 atoms absorb loose neutrons. This causes U-235 to become unstable and split into two light atoms called fission products.