Radiometric dating is a means of determining the "age" of a mineral specimen by determining the relative amounts present of certain radioactive elements.
By "age" we mean the elapsed time from when the mineral specimen was formed.
The New Zealand physicist Ernest Rutherford, suggested in 1905 that the exact age of a rock could be measured by means of radioactivity.
For the first time he was able to exactly measure the age of a uranium mineral.
Dating is not necessary to demonstrate that evolution is a fact.