Fossils Flashcards
What is the minimum age for fossils?
A few thousand years
How old is the oldest fossil?
About 3 million years old.
How is a fossil formed?
- An animal dies and sinks into shallow water
- Sediment covers the animal
- Sediment becomes a rock and preserves the animal
- Weathering and erosion exposes the fossil to the surface
How is a bone preserved in the earth? How does a bone become a fossil?
- The skeleton of an animal becomes buried in layers of sediment
- Pressure from the layers of minerals squeeze out water in the bones. This process is called lithification.
- Minerals fill the gaps where the water has been squeezed from.
This process takes thousands of years and after the bones become fossilized.
What is the definition of a fossil?
A fossil is any type of physical evidence of ancient life.
What is relative dating in terms of fossils?
Relative dating is any method of determining whether an event or object is older or younger than other events or objects.
What is the law of super position?
The law of super position is that in horizontal sedimentary rock layers, the oldest player is at the bottom. Each higher layer is younger than the layer below it. This is only true if there has never been any shift of rock layers.
What is an index fossil?
And Index fossil is something that is found in rock layers of only one geological age and is used to establish the age of the rock layers. Index fossils are found in rock layers all around the world.
An example of an Index fossil is the ancient animal called trilobite.
What clues can we use to determine the layers of rocks?
First we can look at the animals that lived in the rock layers. Each rock layer must contain some trays of the previous rock layers animals because of evolution. From this you can like all of the traces of that animal together until they become extinct.once the animals extinct it does not show up in any younger rock layers.
