Geoscience Reference
In-Depth Information
Tabl e 3 . 1 .
Cenozoic time scale (From
Geological Time Scale, Geological
Society of America, 2009)
Quaternary
0-2.6
Holocene
0-0.01
Pleistocene
0.01-2.6
Neogene
2.6-33.9
Pliocene
2.6-5.3
Miocene
5.3-23.0
Oligocene
23.0-33.9
Paleogene
33.9-65.5
Eocene
33.9-55.8
Palaeocene
55.8-65.5
In discussing the links between continental drift and mountain building, Arthur
Holmes was moved to describe the earth as 'an extremely old rotating electro-magnetic
hydro-dynamic machine with a geochemical structure of great complexity' (Holmes,
1965
, p. 1247). He also speculated that there was a direct causal link between late
Cenozoic mountain building and the inception of glaciation. Flint (
1971
)wasmore
circumspect in his search for the causes of Quaternary glaciation and concluded that
uplift alone was insufficient to trigger an ice age. It was not until a quarter century
later that Ruddiman and Raymo (
1988
) and Ruddiman et al. (
1997
)wereableto
demonstrate in convincing detail the nature of the links between mountain building,
weathering, erosion and climate change. The aims of this chapter are to give a concise
overview of the Cenozoic record of desert evolution and to show the links between
tectonic events, Cenozoic cooling and climatic desiccation.
3.2 Cenozoic tectonism, cooling and desiccation
The cooling and desiccation that characterise the second half of the Cenozoic and gave
rise to the deserts we know today were a direct result of plate tectonic movements that
Tabl e 3 . 2 .
Quaternary time scale (ka BP)
Holocene
0-12 ka
Upper Pleistocene
12-125 ka
Tarentian
Middle Pleistocene
125-780 ka
Ionian
Lower Pleistocene
780-2,580 ka
Calabrian
780-1,800 ka
Gelasian
1,800-2,600 ka
