The Stratigraphic Record: Cyclic or Stochastic?

Layered rocks chiefly record the past operations of Earth's surface sedimentary systems. Beyond this general explanation, however, there is dispute as to whether the 1‐D stratigraphic record provides an inherently and randomly incomplete history of sedimentation, with spatial power‐law properties; or whether it is sufficiently complete, stable in accumulation rate and climate‐sensitive to provide perennial and ubiquitous cyclic records of periodic orbital forcing of terrestrial insolation. The former stochastic model is consistent with the self‐similarity of stratigraphic layering and the analytical evidence for ‘more gap than record’; it is incompatible with pervasive cyclicity. The latter, cyclostratigraphic paradigm has flourished for the last 50 years and the flawed statistics of its conventionally‐applied spectral analysis methods have repeatedly and erroneously confirmed its value, creating numerous false ‘astrochronologies’. It now seems likely that evidence for actual long‐term cyclic sedimentation will prove relatively rare, and that the record's stochastic properties will be found to predominate.