On this page you will find examples of rhythmically bedded sedimentary sequences. The origin of the rhythmicity is manifold, but include Milankovitch scale bedding (http://www.ngdc.noaa.gov/paleo/milankovitch.html), diurnal cycles, neap/spring tide cycles


Rhythmic bedding

Rhythmic bedding in Ordovician Orthoceratid limestone, Lockne Crater, Sweden

Rhythmic bedding in Silurian graptolite shales. Near Checa, prov. de Guadalajara, Spain

Rhythmic bedding in upper Devonian shaly limestones near the Famennian Frasnian Boundary in Nevada (pre-meeting excursion, GSA annual meeting Salt Lake, 1997)

Rhythmic bedding in the Cenomanian Chalk on the British south coast

Rhythmic bedding in the Franciscan banded chert, north of Golden Gate bridge.

Rhythmic bedding in the lower Paleocene of the Pietralata section (Marche, Italy).

These rhytms are probably due to milankovitch forcing, but their thickness does not agree with any of the known cycles