Final answer:
To determine the age of organic remains in rock layers, scientists use radiometric dating, specifically carbon-14 dating, which provides an actual age by measuring radioactive decay. Relative dating methods like stratigraphy help establish a fossil's age relative to other fossils by examining rock stratification.
Step-by-step explanation:
The method used to determine the age of organic remains included in rock layers is called radiometric dating or carbon-14 dating. This approach is a type of chronometric dating method which relies on the principle that radioactive materials, such as the carbon-14 isotope, decay at a known and constant rate. Radiocarbon dating measures the amount of carbon-14 remaining in organic remains; by assessing this residual level, scientists can determine the age of the specimen.
Relative dating methods like stratigraphy are also used to determine the relative order of rock layers and the fossils within them. This technique is based on the law of superposition, which posits that lower layers in a sequence of strata are older than the layers above them. While relative dating can establish whether one fossil is older or younger than another, it cannot provide an exact age.
Chronometric dating, unlike relative dating, can often give a more precise age estimate. The most common chronometric method for dating organic materials is carbon-14 dating, which is valid for samples that are between 300 and 50,000 years old. When organic material is found and collected, it is sealed in nonporous containers to prevent contamination and ensure accurate dating results.