Editing Sedimentary rock (section)

=== Influence of astronomical cycles ===
In many cases facies changes and other lithological features in sequences of sedimentary rock have a cyclic nature. This cyclic nature was caused by cyclic changes in sediment supply and the sedimentary environment. Most of these cyclic changes are caused by [[astronomy|astronomic]] cycles. Short astronomic cycles can be the difference between the tides or the [[spring tide]] every two weeks. On a larger time-scale, cyclic changes in climate and sea level are caused by [[Milankovitch cycles]]: cyclic changes in the orientation and/or position of the Earth's rotational axis and orbit around the Sun. There are a number of Milankovitch cycles known, lasting between 10,000 and 200,000 years.<ref>For a short explanation of Milankovitch cycles, see {{harvnb|Tarbuck|Lutgens|1999|pp=322–323}}; {{harvnb|Reading|1996|pp=14–15}}.</ref>

Relatively small changes in the orientation of the Earth's axis or length of the seasons can be a major influence on the Earth's climate. An example are the [[Quaternary glaciation|ice ages of the past 2.6 million years]] (the [[Quaternary]] [[Geologic time scale|period]]), which are assumed to have been caused by astronomic cycles.{{sfn|Stanley|1999|p=536}}{{sfn|Andersen|Borns|1994|pp=29=32}} Climate change can influence the global sea level (and thus the amount of accommodation space in sedimentary basins) and sediment supply from a certain region. Eventually, small changes in astronomic parameters can cause large changes in sedimentary environment and sedimentation.