1. adj. [Geology]

Pertaining to biostratigraphy, the application of plant and animal fossils to date and correlate strata in order to elucidate Earth history, combining the principles of paleontology and stratigraphy. In the petroleum industry, biostratigraphy often denotes the use of terrestrial (pollen and spores) and marine (diatoms, foraminifera, nanofossils) microfossils to determine the absolute or relative age and depositional environment of a particular formation, source rock, or reservoir of interest.

See: biostratigraphy,  chronostratigraphic chart,  chronostratigraphy,  fossil,  palynology