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 fossil n. The fossil remains of an organism that lived in a particular geologic age, used to identify or date the rock or rock layer in which it is found.