The Cenozoic represents the last 65 million years of the Earth's history, during which time there were major changes in the distribution of continents, land-surface area and oceanic basins as the Earth's plates evolved towards their present configuration. These plate tectonic processes account for the overall deterioration in global climate throughout the Cenozoic from the relatively warm and sea-ice-free Cretaceous and Early Eocene, to the Quaternary icehouse world. This change in global climate is manifest in biotic changes and as a series of stepwise changes in, for example, the oxygen, carbon, strontium and osmium stable isotopes, together with other proxy chemical and geological data (Fig. 3.1).
Once icehouse conditions were established, the high-frequency climate record of glacials and interglacials, and of stadials and interstadials, is best explained by Milankovitch cyclicity. However, higher frequency global climate change on a sub-Milankovitch scale is manifest as millennial, century, decadal, annual and even intra-annual changes. Such very high frequency events are best appreciated in the Quaternary record.
This chapter summarizes the principal changes that took place during the Cenozoic, and considers some of the processes that drove the changes.
CENOZOIC PLATE TECTONICS AND PALAEOGEOGRAPHY
The Cenozoic witnessed the continuing break-up of the supercontinent of Gondwana, the continuing widening of the Atlantic Ocean, the closure of Tethys and the opening of many marginal basins in the western Pacific Ocean.