Final answer:
Archbishop James Ussher calculated the age of the Earth to be around 6000 years old, a belief that was later proven incorrect by scientific evidence showing the Earth's age to be over 4.5 billion years.
Step-by-step explanation:
Archbishop James Ussher calculated the age of the Earth at about 6000 years old. This calculation was based on his interpretation of Biblical chronology and it was widely accepted during his time. Today, through the application of modern scientific methods such as radiometric dating, we understand that the Earth is actually over 4.5 billion years old. The oldest known rocks on Earth are between 4 and 5 billion years old, and radiometric dating of the oldest fossils suggests that they are between 3 and 4 billion years old. These findings drastically revised the perceived timeline of Earth's history beyond what was once believed during the time of Darwin and Ussher.