4. Correlation by Index Fossils
1. The fossilized organism must be easily
recognizable. It must be easy to ID and look
unique.
2. The fossils must be geographically widespread or
found over large areas so that we can use them to
match layers separated by huge distances.
3. The fossil must have lived for only a short time so
that it appears in only a horizontal layer of
sedimentary rocks.
