Which dating method determines the actual age of a fossil?

• A. Fossils
• B. Absolute dating
• C. Relative dating
• D. Geologic time scale

Answer: (B)

Absolute dating provides numeric ages in years by measuring radioactive decay. By analyzing the ratio of a parent isotope to its daughter product and knowing the isotope’s half-life, scientists calculate how long it has been since the rock or fossil formed. Different isotopes are chosen for different time ranges—for example, carbon-14 is useful for relatively recent specimens, while uranium-lead or potassium-argon dating suits much older rocks. Relative dating, in contrast, only places events in order (older or younger) without giving a specific date, and the geologic time scale is a framework of divisions, not a precise date for a fossil. In practice, dating the surrounding rock or minerals provides the actual age assigned to the fossil.