Stratigraphic completeness: Tiered trace fossils provide a measuring stick

Trace-fossil associations commonly display a characteristic vertical zonation (tiering) within the substrate. When burrows of a particular tier become truncated by turbidites, tempestites, or other results of catastrophic events, they provide a simple but quantitative caliper for estimating stratigraphic incompleteness. The minimum amount of penecontemporaneous sea-floor erosion can be determined by types and sequences of trace fossils preserved below event deposits