Which type of dating do index fossils provide the most help for?
A. carbon-14
B. radioactive
C. relative
D. absolute
Index fossils are most helpful for determining the age of rocks and the relative order of geological events. Therefore, the type of dating that index fossils provide the most help for is C. relative dating.
To understand why, let's briefly explain the different types of dating methods:
1. Carbon-14 dating: This method is used to determine the age of organic materials up to around 50,000 years old. It relies on measuring the amount of carbon-14 isotopes remaining in the sample. This method is not suitable for dating rocks or fossils as they do not contain carbon-14.
2. Radioactive dating: Also known as radiometric dating, it is used for determining the absolute age of rocks and minerals. This method relies on the decay of radioactive isotopes in the sample. By measuring the ratio of parent isotopes to daughter isotopes, scientists can calculate the age of the material. However, this method requires the presence of suitable isotopes with known half-lives.
3. Relative dating: This method does not provide an absolute age but rather establishes the relative order of events. It utilizes principles such as superposition, original horizontality, and cross-cutting relationships to determine the sequence of geological events. Index fossils play a significant role in relative dating because they are distinctive fossils that existed for a relatively short period of time and were widespread geographically. By identifying index fossils in different rock layers, scientists can correlate the ages of those layers in different locations. This helps determine the relative age of rocks and the order of geological events.
Therefore, index fossils are most useful for relative dating, as they help establish the relative ages of rocks and the order in which they were deposited.