The Major Types of Stratigraphic Cycle

Abstract

The duration and episodicity of geological events and stratigraphic cyclicity span at least sixteen orders of magnitude, ranging from the repeat time of burst-sweep cycles in turbulent boundary layers (10⁻⁶ years), to plate-tectonic cycles involving the formation and breakup of supercontinents (10⁹ years) (Miall, 1991b; Einsele et al., 1991; Figs. 4.1 and 4.2). The highest-frequency cyclicity of stratigraphic significance is Milankovitch-band cyclicity, over time scales of 10⁴–10⁵ years. Minor cyclicity may be apparent in the geological record as a result of seasonal changes in weather, fluvial discharge, etc., the so-called calendar band of cyclicity (Fischer and Bottjer, 1991). Sunspots and other solar processes generate cyclicity on a 10¹–10²-year scale of cyclicity, the solar band of the time scale. These processes and their products are not discussed in this book.