Formation of Fossils

The study of prehistoric life is called_______________
The fossil record forms the basis of the geologic time scale
and is important in the______________.
Formation of Fossils
Shells, bones, petrified trees, footprints, leaves, or worm
burrows are all considered fossils. They can form in
several different ways including:
1. Original remains:
2. Replaced remains – Remains can be replaced
molecule by molecule as in the case of fossil bones,
teeth, and shells.
3. Molds and Casts – A dead organism makes an
impression into soft sediments
4. Trace Fossils – Evidence of life is preserved in a rock.
5. Carbonaceous Films –
________________are used to date rock layers. The best
index fossils are easily recognizable, abundant, widespread,
and existed for a brief period.
Fossils can give an indication about the
_______________of a rock example. For example, the
Niagara Escarpment was once a _______________as
indicated by the abundant fossilized coral.