PEMBERTON, S. George, SAUNDERS, Thomas D.A., Dept. of Earth & Atmospheric Sciences, University of Alberta, Edmonton, Alberta. Canada. T6G 2E3. MACEACHERN, James A., Earth Sciences Program, Simon Fraser University, Burnaby, B.C. Canada. V5A 1S6

The increasing awareness of event bed deposition in the ancient record or "uniformitarianist catastrophism" has correspondingly led to much consideration of the preservability of such beds. Observations of tempestites in various depositional settings demonstrates a wide variety of preservation styles. The fundamental parameters revolve around the net sedimentation rate, the biogenic mixing rate, and the magnitude of physical reworking, although most proposed quantitative models operate under the assumption that the latter factor is absent. It has been demonstrated that neither sedimentation rate nor biogenic mixing rate are easily defined, both of them masking important, complex affiliated processes and interactions. Few of these have been addressed in detail, despite the effect they have on event bed preservation.

Likewise, foreshores dominated by the ichnogenus Macaronichnus can be totally reworked and primary stratification is destroyed. Most environments are characterized by the interplay of both physical and biogenic processes and the preservability of physical stratification can be dependent on the rate of "biogenic chaos".