The Age of Earth Unit Test
O They are both used to determine the absolute ages of rocks and fossils
O Index fossils are used for absolute dating, but carbon dating is not
O They are both used to determine the relative ages of rocks and fossils
O Carbon dating is used for absolute dating, but index fossils are not.
Which statement is correct about carbon dating and index fossils? (1 point)
The Age of Earth Unit Test
O Carbon dating is used for absolute dating, but index fossils are not.
To determine which statement is correct about carbon dating and index fossils, we need to understand what each method is used for.
Carbon dating is a method used to determine the absolute age of organic materials, such as fossils or artifacts, by measuring the amount of carbon-14 present in the sample. Carbon-14 is an isotope of carbon that is formed in the atmosphere and taken in by living organisms while they are alive. When an organism dies, it no longer takes in carbon-14, and the amount of carbon-14 it contains begins to decrease over time through radioactive decay. By comparing the remaining carbon-14 to the stable carbon isotopes, scientists can calculate the age of the sample.
Index fossils, on the other hand, are used to determine the relative age of rocks or fossils. Index fossils are specific fossils that are known to have existed within a narrow time range and are found in multiple locations. By recognizing the presence of these index fossils in a rock layer, scientists can infer the approximate age of that layer relative to other rock layers.
Now, let's look at the given options:
- "They are both used to determine the absolute ages of rocks and fossils": This statement is incorrect because index fossils are used for relative dating, while carbon dating is used for absolute dating.
- "Index fossils are used for absolute dating, but carbon dating is not": This statement is incorrect because index fossils are not used for absolute dating. They are useful for determining relative ages.
- "They are both used to determine the relative ages of rocks and fossils": This statement is incorrect because carbon dating is used for absolute dating, not relative dating.
- "Carbon dating is used for absolute dating, but index fossils are not": This statement is correct. Carbon dating is a method of absolute dating, while index fossils are used for relative dating.
Therefore, the correct statement is "Carbon dating is used for absolute dating, but index fossils are not."