relative age
Relative age is the age of one object compared to another. It does not give an exact age, but rather a comparison such as "older" or "younger".
Relative age can be determined by Index Fossils and the ordering of rock layers.
Relative age can be determined by Index Fossils and the ordering of rock layers.
Law of Superposition
The Law of Superposition states that each rock layer is older than the one above it. This means that the oldest rock layers will be at the bottom and the youngest rock layers will be at the top. This law ONLY works is the rock layers are preserved in the original order.
Index Fossils
Index Fossils can be used to determine the relative age of rock layers. They serve as a common example or indicator to compare the age of rock layers.
For an organism to be an Index Fossil it must:
-have lived only a short amount of time
-have many fossils that can be found in the rock layers
-be found all over the world
-be unique so that it can be identified
A Trilobite is an example of an index fossil. It had a unique three segment hard-shelled body and lived only a short amount of time in shallow seas roughly 245 million years ago.
For an organism to be an Index Fossil it must:
-have lived only a short amount of time
-have many fossils that can be found in the rock layers
-be found all over the world
-be unique so that it can be identified
A Trilobite is an example of an index fossil. It had a unique three segment hard-shelled body and lived only a short amount of time in shallow seas roughly 245 million years ago.