Conversation so far:
when does the geological record indicate that the earth formed
The geological history of Earth indicates that the Earth formed about 4.54 billion years ago by accretion.
how do we know the earth is 4.54 billion years old
Earth's age is based on evidence from radiometric age-dating of meteorite material and is consistent with the radiometric ages of the oldest-known terrestrial and lunar samples.

Question: when was the age discovered
Self-contained rewrite: when was the age of the earth discovered