Updating uniformitarianism: stratigraphy as just a set of ‘frozen accidents’

Abstract

AbstractIt has long been understood that the stratigraphic record is fragmentary. Barrell was the first to clearly understand the importance of accommodation, and the episodic way in which accommodation is created and removed by geological processes. He demonstrated that typically only a fraction of geological time is represented by accumulated sediment. This point was repeated in influential books by D. Ager. A significant feature of the sedimentary record is the correlation between the duration of a sedimentary unit and its sedimentation rate. Sedimentation rates range over more than eleven orders of magnitude.The durations of stratigraphic gaps, the distribution of layer thicknesses, and sedimentation rates have fractal-like properties, facilitating the integration of our knowledge of the processes of accommodation generation with data on varying sedimentation rates and the scales of hiatuses and processes operating over all time scales.This paper proposes the definition of a suite of Sedimentation Rate Scales to encompass the range of time scales and processes in the stratigraphic record. Assignment of stratigraphic units to the appropriate scale should help to clarify preservation mechanisms, leading to more complete quantitative understanding of the geological preservation machine, and a more grounded approach than earlier treatments of stratigraphic completeness.