Sol definition, the syllable used for the fifth tone of a diatonic scale. See more.
Examples of index fossils. Index fossils (also known as guide fossils, indicator fossils or zone fossils) are fossils used to define and identify geologic periods (or faunal stages).
An index fossil is a fossil representing a plant or animal that existed for a relatively short duration of time. These are the fossils that we want to use for relative dating.