The Kansan glaciation or Kansan glacial (see
Pre-Illinoian
The Pre-Illinoian Stage is used by Quaternary geologists for the early and middle Pleistocene glacial and interglacial periods of geologic time in North America from ~2.5–0.2 Ma (million years ago).
North America
As the oldest stage in th ...
) was a glacial stage and part of an early conceptual climatic and chronological framework composed of four glacial and interglacial stages.
History
Kansan glaciation was used by early
geomorphologist
Geomorphology (from Ancient Greek: , ', "earth"; , ', "form"; and , ', "study") is the scientific study of the origin and evolution of topographic and bathymetric features created by physical, chemical or biological processes operating at or ...
s and
Quaternary geologist
A geologist is a scientist who studies the solid, liquid, and gaseous matter that constitutes Earth and other terrestrial planets, as well as the processes that shape them. Geologists usually study geology, earth science, or geophysics, althoug ...
s to subdivide glacial and nonglacial deposits within north-central United States from youngest to oldest and are as follows:
*
Wisconsin
Wisconsin () is a state in the upper Midwestern United States. Wisconsin is the 25th-largest state by total area and the 20th-most populous. It is bordered by Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake M ...
(glacial)
*
Sangamonian (interglacial)
*
Illinoian (glacial)
*
Yarmouthian (interglacial)
*Kansan (glacial)
*
Aftonian (interglacial)
*
Nebraskan (glacial)
As developed between 1894 and 1909, the Kansan Stage was based on a model that assumed that the Pleistocene deposits contained only two glacial
till
image:Geschiebemergel.JPG, Closeup of glacial till. Note that the larger grains (pebbles and gravel) in the till are completely surrounded by the matrix of finer material (silt and sand), and this characteristic, known as ''matrix support'', is d ...
s and one
volcanic ash
Volcanic ash consists of fragments of rock, mineral crystals, and volcanic glass, created during volcanic eruptions and measuring less than 2 mm (0.079 inches) in diameter. The term volcanic ash is also often loosely used to refer ...
bed within Nebraska and Kansas. Of these two proposed glacial tills, the Kansan till, which defined the Kansan Stage, was the upper of the two glacial tills and the Nebraskan till, which defined the Nebraskan Stage, was the lower of the two glacial tills. It was argued that a single
paleosol
In the geosciences, paleosol (''palaeosol'' in Great Britain and Australia) is an ancient soil that formed in the past. The precise definition of the term in geology and paleontology is slightly different from its use in soil science.
In geolo ...
developed in the Nebraskan till and interglacial deposits separated the Kansan and Nebraskan tills. The paleosol and deposits were used to define the Aftonian (interglacial) stage that separated the Kansan and Nebraskan stages.
[Flint, R.F., 1957, ''Glacial Geology and the Pleistocene Epoch.'' John Wiley & Sons, New York. 553 p. New York][Aber, J.S., 1991, ''Glaciations of Kansas.'' Boreas. vol. 20, no. 4,pp. 297-314][Roy, M., P.U. Clark, R.W. Barendregt, J.R., Glasmann, and R.J. Enkin, 2004]
''Glacial stratigraphy and paleomagnetism of late Cenozoic deposits of the north-central United States''
, PDF version, 1.2 MB. Geological Society of America Bulletin, vol. 116, no. 1-2; pp. 30-41; [Hallberg, G.R., 1986, ''Pre-Wisconsin glacial stratigraphy of the Central Plains region in Iowa, Nebraska, Kansas, and Missouri'', Quaternary Science Reviews. vol. 5, pp. 11-15.]
In time, the stratigraphy of Pleistocene deposits was found to be far more complex than the two glacial tills and one volcanic ash bed on which the Yarmouthian, Kansan, Nebraskan, and Aftonian glacial - interglacial nomenclature was originally based. Detailed research by Boellstorff demonstrated that the two glacial tills and one ash bed stratigraphic model, on which the Yarmouthian, Kansan, Nebraskan, and Aftonian glacial - interglacial nomenclature was based, was completely wrong.
[Boellstorff, J., 1978a, ''Chronology of some Late Cenozoic deposits from the central United States and the Ice Ages. ''Transactions of the Nebraska Academy of Science. vol 6, pp. 35–49][Boellstorff, J., 1978b, North American Pleistocene stages reconsidered in the light of probable Pliocene-Pleistocene continental glaciation.'' Science. vol. 202, pp. 305–307.][Easterbrook, D.J., and J. Boellstorff, 1984, ''Paleomagnetism and Chronology of Early Pleistocene Tills in the Central United States.'' in W.C. Mahaney, ed., pp. 73-90. Correlation of Quaternary Chronologies. Norwich, United Kingdom, Geo Books.] This research found that at the type locations for the Kansan and Nebraskan tills numerous glacial tills, which were separated by numerous paleosols, existed. In addition,
fission track dating
Fission track dating is a radiometric dating technique based on analyses of the damage trails, or tracks, left by fission fragments in certain uranium-bearing minerals and glasses. Fission-track dating is a relatively simple method of radiomet ...
and geochemical analysis demonstrated what was thought to be one
volcanic ash
Volcanic ash consists of fragments of rock, mineral crystals, and volcanic glass, created during volcanic eruptions and measuring less than 2 mm (0.079 inches) in diameter. The term volcanic ash is also often loosely used to refer ...
layer was actually three separate volcanic ash layers, i.e. the 602,000 year-old Lava Creek B volcanic ash; the 1,293,000 year-old Mesa Falls volcanic ash, and the 2,003,000 year-old Huckleberry volcanic ash.
In addition, detailed studies of glacial tills in Kansas have found that at different outcrops, the same glacial till has been identified as being either a "Kansan" till or "Nebraskan" till.
Also, it was found that the Afton Soil (paleosol), which was used define the Aftonian interglacial, is buried by a younger glacial till that was considered to be a "type Nebraskan" glacial till as well as having developed in an older glacial till that was considered to be a "type Nebraskan" glacial till.
[Richmond, G.M. and D.S. Fullerton, 1986, ''Summation of Quaternary glaciations in the United States of America''. Quaternary Science Reviews. vol. 5, pp. 183-196.] As a result, the basic assumptions on which the Yarmouthian (interglacial), Kansan (glacial), Aftonian (interglacial), and Nebraskan (glacial) nomenclature was originally defined was found to be lacking any scientific basis. As a result, this nomenclature was abandoned by Quaternary geologists in North America and merged into the
Pre-Illinoian Stage.
References
External links
*Aber, J.S., 2006
''Regional Glaciation of Kansas and Nebraska.''Emporia State University, Emporia, Kansas.
*anonymous, 1997
Work Group on Geospatial Analysis of Glaciated Environments (GAGE), INQUA Commission on Glaciation, Emporia State University, Emporia, Kansas.
*anonymous, 2000
Work Group on Geospatial Analysis of Glaciated Environments (GAGE), INQUA Commission on Glaciation, Emporia State University, Emporia, Kansas.
*anonymous, 2007
Subcommission on Quaternary Stratigraphy, Department of Geography, University of Cambridge, Cambridge, England
*Gibbard, P.L., S. Boreham, K.M. Cohen and A. Moscariello, 2007
''Global chronostratigraphical correlation table for the last 2.7 million years v. 2007b.'' jpg version 844 KB. Subcommission on Quaternary Stratigraphy, Department of Geography, University of Cambridge, Cambridge, England
*Hallberg, G.R., ed., 1980a
''Pleistocene stratigraphy in east-central Iowa.'' PDF version 15.6 MB. Technical information Series. no. 10. Iowa Geological Survey Bureau, Ames, IA.
*Hallberg, G. R., ed., 1980b
''Illinoian and Pre-Illinoian stratigraphy of southeast Iowa and adjacent Illinois.'' PDF version 19.3 MB. Technical information Series. no. 11. Iowa Geological Survey Bureau, Ames, IA.
*Hallberg, G. R., T. E. Fenton, T. J. Kemmis, and G. A. Miller, 1980
''Yarmouth Revisited: Midwest Friends of the Pleistocene 27th Field Conference.'' PDF version 4.6 MB. Guidebook no. 3. Iowa Geological Survey Bureau, Ames, IA.
*Roy, M., P.U. Clark, R.W. Barendregt, J.R., Glasmann, and R.J. Enkin, 2004
''Glacial stratigraphy and paleomagnetism of late Cenozoic deposits of the north-central United States.'' PDF version, 1.2 MB. Geological Society of America Bulletin. vol. 116, no. 1-2; pp. 30–41;
See also
*
Glacial history of Minnesota
*
Ice age
An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages and gre ...
*
Illinoian Stage
The Illinoian Stage is the name used by Quaternary geologists in North America to designate the period c.191,000 to c.130,000 years ago, during the middle Pleistocene, when sediments comprising the Illinoian Glacial Lobe were deposited. It precedes ...
*
Last Glacial Maximum
*
Pre-Illinoian Stage
*
Sea level rise
Globally, sea levels are rising due to human-caused climate change. Between 1901 and 2018, the globally averaged sea level rose by , or 1–2 mm per year on average.IPCC, 2019Summary for Policymakers InIPCC Special Report on the Ocean and Cry ...
*
Timeline of glaciation
There have been five or six major ice ages in the history of Earth over the past 3 billion years.
The Late Cenozoic Ice Age began 34 million years ago, its latest phase being the Quaternary glaciation, in progress since 2.58 million years ago ...
*
Yarmouthian Interglacial
{{Continental Glaciations
Glaciology of the United States
Ice ages
Pleistocene events