The Droser-Bottjer ichnofabric index is a method used to quantify the degree of

bioturbation Bioturbation is defined as the reworking of soils and sediments by animals or plants. It includes burrowing, ingestion, and defecation of sediment grains. Bioturbating activities have a profound effect on the environment and are thought to be a ...

in a

sedimentary rock Sedimentary rocks are types of rock (geology), rock formed by the cementation (geology), cementation of sediments—i.e. particles made of minerals (geological detritus) or organic matter (biological detritus)—that have been accumulated or de ...

. It involves grading the amount of

trace fossil A trace fossil, also called an ichnofossil (; ), is a fossil record of biological activity by lifeforms, but not the preserved remains of the organism itself. Trace fossils contrast with body fossils, which are the fossilized remains of part ...

activity on a scale of 1–6; a value of 1 indicates that bioturbation is entirely absent, whereas the highest grade would involve a

bedding plane In geology, a bed is a layer of sediment, sedimentary rock, or volcanic rock "bounded above and below by more or less well-defined bedding surfaces".Neuendorf, K.K.E., J.P. Mehl, Jr., and J.A. Jackson, eds., 2005. ''Glossary of Geology'' (5th ed ...

containing over 60% trace fossil cover.

Application

Ichnofabric index can be applied in either a vertical or horizontal aspect. The vertical component provides an indication of the interplay between physical and chemical aspects of the environment and the degree of biological activity. The vertical ichnofossil index is harder to measure; it involves quantifying the amount of disturbance to the original sedimentary fabric.

References

Trace fossils {{trace-fossil-stub