Polystrate fossils are fossils which occupy or span through more than one strata of rock. They are usually trees, and whole polystrate fossil forests have been found in various places. Rarely, they are fossilized bones. They are used by young Earth creationists as evidence against the uniformitarian timescale.
Implications for uniformitarianism
Uniformitarianism claims that the many strata of rock in the geologic column have been formed slowly and at a generally uniform rate over thousands and millions of years. However, since polystrate fossils occupy more than one strata, this suggests that the strata were formed rapidly, as they would have been in the Great Flood (rather than the strata growing up around the fossils). See also catastrophism, the rival theory to uniformitarianism.
The common uniformitarian response is that if the trunk of a tree is buried, it will not necessarily die. A new root system may grow out from where the trunk was buried, and the tree may regenerate itself several times, such that by the time it finally dies, its trunk will have occupied several strata, all during its lifetime.
While certainly possible in theory, this may not account for all of the many polystrate trees which have been found.
- https://creation.com/polystrate-fossils-evidence-for-a-young-earth (Creationist)
- https://www.icr.org/index.php?module=articles&action=view&ID=1144 (Creationist)
- http://www.talkorigins.org/faqs/polystrate/trees.html (Uniformitarian, Secular)
- http://www.answersincreation.org/rebuttal/icr/drjohn/drjohn_81.htm (Uniformitarian, Old Earth Creationist)