The geological timescale was first developed using the fossil record, but this provided only a system of relative dating; absolute dates weren't established until the discovery of: -

... radioactive decay.

Explanation:

Radioactive decay

Explanation:

Radioactive decay which is a property of several elements found on the earth involves the emission of charged particles and energy of unstable nuclei of radioactive atoms, thereby becoming stable with time. The rate of radioactive decay is often referred to as half-life of that element, and could be as more than millions of years. Radioactive elements that undergo radioactive decay have made it possible for a more accurate dating to be achieved using the known decay rates of radioactive materials.

after making a punnet square using bv bv bv bv you will find that the ratio will be 9: 7 or a 128.6% probability.

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