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).
If two rock layers have the same index fossils, then theyâre probably about the same age. You can watch a video about index fossils and how they are used at his link: [Insert a link to a video about using index fossils to match rock layers in different places.]