Who discovered radiometric dating?

Answer 1

Take a look at this:

"In 1896 Henri Becquerel and Marie Curie discovered that certain isotopes undergo spontaneous radioactive decay, transforming into new isotopes. Atoms of a parent radioactive isotope randomly decay into a daughter isotope. Over time the number of parent atoms decreases and the number of daughter atoms increases. Rutherford and Soddy (1902) discovered that the rate of decay of a radioactive isotope depends on the amount of the parent isotope remaining. Later it was found that half of the parent atoms occurring in a sample at any time will decay into daughter atoms in a characteristic time called the half-life."

from http://myweb.cwpost.liu.edu/vdivener/notes/radiometric_dating.htm

These discoveries lead to the practical application of radiometric dating so you could probably credit the discovery to these individuals.

Answer 2

Radiometric dating was discovered by scientists Bertram Boltwood in the early 20th century. Boltwood used the radioactive decay of uranium and thorium minerals to determine the age of rocks and minerals.