Delineation of specific segments of the Paleozoic geological column by palynological methods is based on the concept that plant composition throughout geological time underwent changes that are recorded in the recoverable spores and pollen grains. These changes are largely the result of plant evolution and paleoecology.

The application of Paleozoic palynology originated 32 years ago with attempts to correlate economically important coals. In subsequent years, palynological data have been used in correlation studies of other strata, both non-marine and marine.

Separate thresholds of guide fossils are required when plant microfossils from different environments are compared in attempting to establish correlation lines. The coal-swamp environment, at a given point in time, has a particular set of fossils not necessarily duplicated in other non-marine environments elsewhere.

In recent years, palynological data have become available from many localities throughout the world. From these data it is possible to evaluate selected taxa potentially useful for correlation studies.

Palynology has certain limitations inherent to the science and others common to biological methods of correlation. Although palynology can not be used in every correlation problem, it has been useful and practical for parts of the geological column, in some cases after other biological methods have failed to be definitive.

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