How do scientists know when things happened in the past?
Ans: Scientists use dating techniques based on a variety of physical, geological, and chemical principles. When a fossil primate is found, research is done to determine what kind of geological formation it came from. Every formation was laid down at some period of time, and researchers can date material that is in direct association with the fossils, or they can date strata that are above (younger than) or below (older than) the specimen to give them a range of dates. For example, if one of the strata was formed from a volcanic eruption, scientists can use the Potassium-Argon dating technique to determine the age of the volcanic rocks associated with that stratum. If there is organic material in a recent stratum or fossil, scientists can use the Carbon-14 method to obtain a date.
