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).
Index fossils Fossils of organisms that lived during a relatively short geologic time span. The three conditions To be an index fossil, a fossil organism must be found throughâ¦out the world. It must be easy to identify and many fossils of that organism must exist.