When will a fossil be used in finding the absolute age of rocks?(1 point)
A fossil can be used in finding the absolute age of rocks when it is used as an index fossil. An index fossil is a distinctive fossil species that is known to have lived only during a specific time period. By finding the index fossil in a rock layer, scientists can establish the age of that rock layer based on the known age range of the index fossil.
To determine the absolute age of rocks, fossils can be used in a process called biostratigraphy. This approach relies on the fact that different species of organisms existed during specific time periods in Earth's history. By studying the fossil assemblages within the layers of sedimentary rocks, scientists can correlate the age of the rock with the age of the fossils it contains.
To use a fossil for determining the absolute age of rocks, follow these steps:
1. Identify the fossil: First, you need to be able to recognize and classify the fossil you find in the rock. This requires some knowledge of paleontology and the characteristics of different organisms.
2. Research the fossil's time range: Each species has a specific time range during which it existed on Earth. Consult reliable sources such as scientific literature, paleontological databases, or expert opinions to determine the approximate age range for the fossil you have identified.
3. Analyze the rock layer: Examine the rock layer where the fossil was found. Take note of its characteristics, such as its position in the geologic column, any associated fossils, and the types of sedimentary rocks present.
4. Compare the fossil's age range with known geologic timescales: Geologists have established detailed geologic timescales that arrange Earth's history into distinct time periods. Compare the age range of the fossil to these timescales to estimate the absolute age of the rock layer. This involves matching the fossil's known time range to the corresponding geologic time period.
It's important to note that while biostratigraphy is a valuable tool, it does not provide an exact age. Instead, it provides an estimate based on the known time range of the fossil species. To obtain a more precise absolute age, other dating methods such as radiometric dating may be employed.