Template:Geologic time scale
Revision as of 03:45, 3 March 2013 by 24.218.110.195 (talk)
- ↑ Paleontologists often refer to faunal stages rather than geologic (geological) periods. The stage nomenclature is quite complex. For an excellent time-ordered list of faunal stages, see "The Paleobiology Database". Retrieved 2006-03-19.
- ↑ 2.0 2.1 Dates are slightly uncertain with differences of a few percent between various sources being common. This is largely due to uncertainties in radiometric dating and the problem that deposits suitable for radiometric dating seldom occur exactly at the places in the geologic column where they would be most useful. The dates and errors quoted above are according to the International Commission on Stratigraphy 2012 time scale. Where errors are not quoted, errors are less than the precision of the age given. Dates labeled with a * indicate boundaries where a Global Boundary Stratotype Section and Point has been internationally agreed upon: see List of Global Boundary Stratotype Sections and Points for a complete list.
- ↑ References to the "Post-Cambrian Supereon" are not universally accepted, and therefore must be considered unofficial.
- ↑ Historically, the Cenozoic has been divided up into the Quaternary and Tertiary sub-eras, as well as the Neogene and Paleogene periods. The 2009 version of the ICS time chart recognizes a slightly extended Quaternary as well as the Paleogene and a truncated Neogene, the Tertiary having been demoted to informal status.
- ↑ The start time for the Holocene epoch is here given as 11,700 years ago. For further discussion of the dating of this epoch, see Holocene.
- ↑ 6.0 6.1 In North America, the Carboniferous is subdivided into Mississippian and Pennsylvanian Periods.
- ↑ The Precambrian is also known as Cryptozoic.
- ↑ 8.00 8.01 8.02 8.03 8.04 8.05 8.06 8.07 8.08 8.09 8.10 8.11 8.12 8.13 The Proterozoic, Archean and Hadean are often collectively referred to as the Precambrian Time or sometimes, also the Cryptozoic.
- ↑ 9.00 9.01 9.02 9.03 9.04 9.05 9.06 9.07 9.08 9.09 9.10 9.11 Defined by absolute age (Global Standard Stratigraphic Age).
- ↑ Though commonly used, the Hadean is not a formal eon and no lower bound for the Archean and Eoarchean have been agreed upon. The Hadean has also sometimes been called the Priscoan or the Azoic. Sometimes, the Hadean can be found to be subdivided according to the lunar geologic time scale. These eras include the Cryptic and Basin Groups (which are subdivisions of the Pre-Nectarian era), Nectarian, and Early Imbrian units.
- ↑ 11.0 11.1 11.2 11.3 These unit names were taken from the Lunar geologic timescale and refer to geologic events that did not occur on Earth. Their use for Earth geology is unofficial. Note that their start times do not dovetail perfectly with the later, terrestrially defined boundaries.
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