Editing Paleoclimatology (section)

====Sedimentary content====
On a longer time scale, geologists must refer to the sedimentary record for data.

* Sediments, sometimes lithified to form rock, may contain remnants of preserved vegetation, animals, plankton, or [[Palynology|pollen]], which may be characteristic of certain climatic zones.
* Biomarker molecules such as the [[alkenones]] may yield information about their temperature of formation.
* Chemical signatures, particularly [[Mg/Ca]] ratio of [[calcite]] in [[Foraminifera]] tests, can be used to reconstruct past temperature.
* Isotopic ratios can provide further information. Specifically, the {{delta|18|O|link}} record responds to changes in temperature and ice volume, and the {{delta|13|C|link}} record reflects a range of factors, which are often difficult to disentangle.

[[File:Core+Repository+core samples2.jpg|right|thumb|Sea floor core sample labelled to identify the exact spot on the sea floor where the sample was taken. Sediments from nearby locations can show significant differences in chemical and biological composition.]]
;[[Sedimentary facies]]
On a longer time scale, the rock record may show signs of [[sea level]] rise and fall, and features such as [[Dune#Lithified dunes|"fossilised" sand dunes]] can be identified. Scientists can get a grasp of long-term climate by studying [[sedimentary rock]] going back billions of years. The division of Earth history into separate periods is largely based on visible changes in sedimentary rock layers that demarcate major changes in conditions. Often, they include major shifts in climate.