.Ichnological criteria for the recognition and interpretation of erosional discontinuities

Trace fossils are both sedimentologic and paleontologic entities and as such, represent a unique blending of potential environmental indicators in the stratigraphic record. In the past, trace fossils were considered to be almost useless in stratigraphic analysis due to their negligible value in biostratigraphy. However, trace fossil suites can be employed effectively to aid in the recognition of various types of discontinuities and to assist in their genetic interpretation. Ichnology may be employed to identify and interpret surfaces of sequence stratigraphic significance in two main ways: 1) through the recognition of substrate controlled ichnofacies, which mark time gaps between the original deposition of a unit (with or without softground burrowing) and later superimposition of a post-depositional trace fossil assemblage, and 2) through careful analysis of vertical ichnological successions (analogous to facies successions). Integrating the data derived from substrate controlled ichnofacies with data from vertical ichnological successions provides a powerful tool for the recognition and interprretation of key stratal boundaries.