HISTORY OF PLEISTOCENE STUDY

The "Pleistocene" concept grew out of scientific interest in natural phenomenon during the Age of Reason. The interest was based on natural observations
TWO HYPOTHESES were advanced to explain the natural features
    1. DILUVIALISTS: Biblical Noachian deluge. Poles flooded & icebergs rafted boulders "CATASTROPHIST" abrupt, unique event "DRIFT" implies water transport for sediments: till, erratics
    2. GLACIALISTS: Glacial Expansion. Emphasis on Uniformitarianism (James Hutton). Called on existing natural processes.
      "ICEBERG THEORY" periodic expansion and contraction of ice caps over water-covered continents, one of their "bad" ideas
      SWISS SCIENTISTS - Ignace Venetz, Jean De Carpentier. Compared the geomorphology at mouth of Swiss glaciers with features farther down- valley (striations, faceted boulders)
        Louis Agassiz - Swiss zoologist-paleontologist July 24, 1837 Presidential address, Swiss Society of Natural Science.
        Edward Hitchcock 1841 reviewed Agassiz's work and applied it to his "Geology of Massachusetts" (originally diluvial)
The observations eventually lead to a general concept of the "Pleistocene"
    WHAT -- Concept of an Ice Age = colder
    WHEN -- in the not-too distant past
Extinct organisms: THE GEOLOGIC TIME SCALE is based on distributions of organisms in time
    Charles Lyell 1839 used "Pleistocene" for rocks in London and Paris basins in which over 70% of the fauna (mollusks) living.
    Edward Forbes 1846 referred to Pleistocene as 'Glacial Epoch' believe that we are in warm 'postglacial time' after the ice age.
At the time the "Pleistocene" concept was forming, the rocks at the Earth's were categorized
    Quaternary: overlying the Tertiary rocks (Desnoyers, 1829)
    Tertiary: redeposited Secondary rocks
    Secondary: sedimentary rocks formed from Primary rocks
    Primary: ancient crystalline rocks (igneous)

With more descriptions and comparison, these early terms became part of the Geologic Time Scale


How is the Beginning and End of the Quaternary Defined?

    Subdivisions of Quaternary were based on evidence of Ice Age Environments
      1. fossils: the distribution of animals & plants in time and space
      2. sediments: tills, "drift"

TRADITIONAL DEFINITION for the beginning of the Pleistocene (1948!): The First appearance of cold-loving animals in Mediterranean Basin. This is just above the Olduvai normal (1.62 Ma) paleomagnetic event -- 1.8 Ma
    CALABRIAN (Italy) type section indicators of cold
    CURRENT DEFINITION
      2.6 Ma rapid cooling, boundary of Gauss/Matuyama paleomagnetic epochs
The beginning of the Pleistocene is time-transgressive and gradual
    - Eocene/Oligocene: Antarctic Ice forms
    - 15 MY: Minor fluctuations in sea core composition begin
    - 2.6 MY: major fluctuations, earliest raised beaches
    - 0.7 MY: B/M magnetic boundary Arctic Ice forms
          7 glacial cycles since then


The end of the Pleistocene is even harder to define
  • Regional differences, ecosystem variations, proxy indicator disparities
  • The Holocene is just another interglacial - more "Pleistocene" to come
  • Global (Marine) definition based on sea-level raise (-125 m LGM) Ruddiman & Duplessy (1985 QR 23:1-17)

    example: Flooding of Beringia two stages
  • 10,000 (14C) yr 'Nice Round Number' D.M. Hopkins (1975)
  • 11,000 14C yr (12,900 cal yr) Firestone et al (2005) Y.D. E.T.


GLACIAL CHRONOLOGIES
PLEISTOCENE STRATIGRAPHY: GLACIAL STAGES (4 or more)
    - 1847 Edouard Collomb noted 2 layers of "drift" separated by an "interglacial" Vosges Fr
    - 1877 James Geikie proposed 4 glaciations for East Anglia
      - Since that time Pleistocene subdivisions have been based on glacial advances ("just 4" continues today)
      - Names of the glacial advances are applied to the other climate-related phenomena
        -Sea Level
        -Pluvial Lakes
        -Loess Sheets
        -Mammalian Faunas
    - 1894 J. Geikie U.S.A. Midwestern chronology


Central North American ("Midwestern") Glacial Chronology
(T.C. Chamberlin, F. Leverett (1894-1909))
Glacials named for U.S. Midwestern States
Interglacials named for Counties and Towns in Midwest
WISCONSIN  
SANGEMON (Co. Ill.)
ILLINOIAN  
YARMOUTH (Iowa)
KANSAN  
AFTONIAN (Afton Junction, Iowa)
NEBRASKAN  
"Never Kiss In Winter -- After You've Sneezed"
More Detail


1909 A.Penck and E.Bruckner - Alpine Glacial Chronology
    Glacials named for tributaries of the Danube River in Germany.
    Based on Relative levels of river terraces separated by weathering and soils.




ALPINE N. EUROPE ENGLAND
WÜRM Weichsel Weichsel
Riss-Wurm Eem Ipswich
RISS Warthe Gipping
Mindel-Riss Saale/Warthe Hoxne
MINDEL Saale Lowestoft
Gunz-Mindel Holstein Cromer
GUNZ Elster Beeston
  Cromerian Paston
  Menapian Baventian
"Good Men Resist War"


TRADITIONAL SUBDIVISIONS OF THE LAST ICE AGE (WISCONSIN):
      stadials (minor glacial advances): Valderan, Woodfordian, Altonian. separated by
interstadials (minor retreats): Twocreekan, Farmdalian, Port Talbot
Midwestern age (yr B.P.) DNAG ROCKY MT. 18O stages
Holocene 0 -10,000 Holocene   1
Greatlakean 10,000-11,000      
Twocreekan 11,000-12,500   PINEDALE  
Woodfordian 12,500-25,000 Late Wisconsin adv. 15-20 K 2
Farmdalian 25,000-28,000      
Altonian 28,000-50,000 Mid Wisconsin   3-4
Port Talbot 50,000-55,000     4
Early Wisconsin 55,000-100,000 Early Wisconsin   5a b
    Middle Pleistocene   19 - 6
    Early Pleistocene   100 - 20
Frye & Willman 1973   Fillmore & Linebeck 1979
Pierce 1976  
http://www.uwgb.edu/dutchs/EarthSC202Notes/glacial.htm



'CURRENT' SUBDIVISIONS OF THE LAST GLACIATION (ocean & ice cores)
(Heinrich, 1988; Broeker, 1994; Bender et al., 1994; Grimm et al., 1993) 6 abrupt (decade - century) large (5 oC) cold events during last glaciations - iceberg surges


Heinrich Events
H1 (16.5 Ky)
H2 (23 Ky)
H3 (29 Ky)
H4 (40 Ky)
H5 (51 Ky)
H6 (68 Ky)

Appearance
Distribution
heinrich.gif






GLOBAL DISTRIBUTSION OF D-O AND HEINRICH EVENTS
    Similar timing but amplitude greater in Greenland (3oC) vs. Antarctic
    A LAG between Antarctic and Arctic events
    TBS: Thermal Bipolar Seesaw

APPLICATION OF THE CLASSICAL GLACIAL TERMINOLOGIES
The problem with continental glacial chronologies is stratigraphic correlation
  • Successive advances bury and erase sediments of earlier glaciations
  • Continuous environment of deposition on continents; e.g., Nebraskan stage known from a few scattered exposures and bore holes.
  • Attempts to correlate with LAND MAMMAL AGES have been dubious (lacked absolute dating)
    • assumed that because the Nebraskan is the earliest glaciation and the Blancan is the earliest Quaternary Mammal age that they're synchronous
  • The Classical glacial-sediment sequences are known to include more than one glacial advance; e.g. the WURM has 2, the RISS has 3 (Kukla), the ILLINOIAN encompasses 5 global glaciations. SUPERSTAGE has been proposed; e.g., the ILLINOIAN SUPERSTAGE comprised of 6 glacial advances, with 6 lithologically distinct tills separated by soils
    THEREFORE, most Quaternary scientists have adopted the chronology of the
    MARINE OXYGEN ISOTOPE RECORD
READINGS

HOMEWORK

LINKS:
    Alley, R.B. and the Committee on Abrupt Climate Change. 2003. Abrupt climate change: Inevitable surprises. National Academies Press. www.nap.edu/books/0309074347/html/R4.html

    Flessa, K.W. and the Committee on the Geologic Record of Biosphere Dynamics, National Research Council. 2005. The Geological Record of Ecological Dynamics: Understanding the Biotic Effects of Future Environmental Change. National Academies Press.
    www.nap.edu/books/0309095808/html

    Martinson, D.G. and the Climate Research Committee. 1995. Natural climate variability on decade-to-century time scales. National Academies Press.
    www.nap.edu/books/0309054494/html/index.html

    Webb, S.D. and Opdyke, N.D. 1995. Global climatic influence on Cenozoic land mammal faunas. National Academies Press.
    www.nap.edu/books/0309051274/html/184.html