1. Developing a Timescale

A store of core samples. https://handwiki.org/wiki/index.php?curid=1473231

In 1957 Emiliani moved to the University of Miami to have access to core-drilling ships and equipment, and began to drill in the Caribbean and collect core data. A further important advance came in 1967, when Nicholas Shackleton suggested that the fluctuations over time in the marine isotope ratios that had become evident by then were caused not so much by changes in water temperature, as Emiliani thought, but mainly by changes in the volume of ice-sheets, which when they expanded took up the lighter oxygen-16 isotope in preference to the heavier oxygen-18.^[1] The cycles in the isotope ratio were found to correspond to terrestrial evidence of glacials and interglacials. A graph of the entire series of stages then revealed unsuspected advances and retreats of ice and also filled in the details of the stadials and interstadials.

More recent ice core samples of today's glacial ice substantiated the cycles through studies of ancient pollen deposition. Currently a number of methods are making additional detail possible. Matching the stages to named periods proceeds as new dates are discovered and new regions are explored geologically. The marine isotopic records appear more complete and detailed than any terrestrial equivalents, and have enabled a timeline of glaciation for the Plio-Pleistocene to be identified.^[2] It is now believed that changes in the size of the major ice sheets such as the historical Laurentide Ice Sheet of North America are the main factor governing variations in the oxygen isotope ratios.^[3]

The MIS data also matches the astronomical data of Milankovitch cycles of orbital forcing or the effects of variations in insolation caused by cyclical slight changes in the tilt of the earth's axis of rotation – the "orbital theory". Indeed, that the MIS data matched Milankovich's theory, which he formed during World War I, so well was a key factor in the theory gaining general acceptance, despite some remaining problems at certain points, notably the so-called 100,000-year problem. For relatively recent periods data from radiocarbon dating and dendrochronology also support the MIS data.^[4] The sediments also acquire depositional remanent magnetization which allows them to be correlated with earth's geomagnetic reversals. For older core samples, individual annual depositions cannot usually be distinguished, and dating is taken from the geomagnetic information in the cores.^[5] Other information, especially as to the ratios of gases such as carbon dioxide in the atmosphere, is provided by analysis of ice cores.

The SPECMAP Project, funded by the US National Science Foundation, has produced one standard chronology for oxygen isotope records, although there are others. This high resolution chronology was derived from several isotopic records, the composite curve was then smoothed, filtered and tuned to the known cycles of the astronomical variables. The use of a number of isotopic profiles was designed to eliminate 'noise' errors, that could have been contained within a single isotopic record.^[6] Another large research project funded by the US government in the 1970s and 1980s was Climate (CLIMAP), which to a large degree succeeded in its aim of producing a map of the global climate at the Last Glacial Maximum, some 18,000 years ago, with some of the research also directed at the climate some 120,000 years ago, during the last interglacial. The theoretical advances and greatly improved data available by the 1970s enabled a "grand synthesis" to be made, best known from the 1976 paper Variations in the earth’s orbit: pacemaker of the ice ages (in Science), by J.D. Hays, Shackleton and John Imbrie, which is still very widely accepted today, and covers the MIS timescale and the causal effect of the orbital theory.^[7]

In 2010 the Subcommission on Quaternary Stratigraphy of the International Commission on Stratigraphy dropped other lists of MIS dates and started using the Lisiecki & Raymo (2005) LR04 Benthic Stack, as updated. This was compiled by Lorraine Lisiecki and Maureen Raymo.^[8]

2. Stages

Marine core sections from the South Atlantic, about a million years old. https://handwiki.org/wiki/index.php?curid=1428251

The following are the start dates (apart from MIS 5 sub-stages) of the most recent MIS (Lisiecki & Raymo 2005, LR04 Benthic Stack). The figures, in thousands of years ago, are from Lisiecki's website.^[9] Numbers for substages in MIS 5 denote peaks of substages rather than boundaries.

MIS     Start Date

• MIS 1 – 14 kya, end of the Younger Dryas marks the start of the Holocene. The LR04 date of 14 kya had to accommodate less well studied time intervals, and the generally accepted date of 11.7 kya is to be preferred.^[10]
• MIS 2 – 29
• MIS 3 – 57^[11] (MIS 2-4 is called the Last Glacial Period, Wisconsinan glaciation in North America, Weichselian glaciation in Europe)
• MIS 4 – 71
• MIS 5 – 130, usually sub-divided into a to e:
  • MIS 5a – 82 (peak of interglacial sub-stage)
  • MIS 5b – 87 (peak of glacial sub-stage)
  • MIS 5c – 96 (peak of interglacial sub-stage)
  • MIS 5d – 109 (peak of glacial sub-stage)
  • MIS 5e – 123 (peak of Eemian interglacial sub-stage, or Ipswichian in Britain)
• MIS 6 – 191 (Illinoian glacial in North America, Saalian in northern Europe and Wolstonian in Britain)
• MIS 7 – 243 (Aveley Interglacial in Britain)
• MIS 8 – 300
• MIS 9 – 337 (Purfleet Interglacial in Britain)^[12]
• MIS 10 – 374
• MIS 11 – 424 (Hoxnian Interglacial in Britain)
• MIS 12 – 478 (Anglian Glacial in Britain, Elster glaciation in North America)
• MIS 13 – 524
• MIS 14 – 563
• MIS 15 – 621
• MIS 16 – 676
• MIS 17 – 712
• MIS 18 – 761
• MIS 19 – 790 (Brunhes–Matuyama reversal)
• MIS 20 – 814
• MIS 21 – 866

The list continues to MIS 104, beginning 2.614 million years ago.

3. Older Versions

The following are the start dates of the most recent MIS, in kya (thousands of years ago). The first figures are derived by Aitken & Stokes from Bassinot et al. (1994), with the figures in parentheses alternative estimates from Martinson et al. for stage 4 and for the others the SPECMAP figures in Imbrie et al. (1984). For stages 1–16 the SPECMAP figures are within 5 kya of the figures given here. All figures up to MIS 21 are taken from Aitken & Stokes, Table 1.4, except for the sub-stages of MIS 5, which are from Wright's Table 1.1.^[13]

• MIS 1 – 11 kya, end of the Younger Dryas marks the start of the Holocene, continuing to the present
• MIS 2 – 24 near Last Glacial Maximum
• MIS 3 – 60
• MIS 4 – 71 (74)
• MIS 5 – 130, includes the Eemian; usually sub-divided into a to e:
  • MIS 5a – 84.74
  • MIS 5b – 92.84
  • MIS 5c – 105.92
  • MIS 5d – 115.105
  • MIS 5e – 130.115
• MIS 6 – 190
• MIS 7 – 244
• MIS 8 – 301
• MIS 9 – 334
• MIS 10 – 364
• MIS 11 427, the most similar to MIS 1.
• MIS 12 – 474
• MIS 13 – 528
• MIS 14 – 568
• MIS 15 – 621
• MIS 16 – 659
• MIS 17 – 712 (689)
• MIS 18 – 760 (726)
• MIS 19 – 787 (736)
• MIS 20 – 810 (763)
• MIS 21 – 865 (790)

Some older stages, in mya (millions of years ago):^[14]

• MIS 22 – 1.03 mya, marking the end of the Bavelian period in Europe
• MIS 62 – 1.75, end of the Tiglian
• MIS 103 – 2.588, end of the Pliocene and start of the Pleistocene, on the INQUA time scale (older definitions put this change at 1.806 mya – the MIS date is unaffected)

The content is sourced from: https://handwiki.org/wiki/Physics:Marine_isotope_stage