The Sangamonian Stage (or Sangamon interglacial) is the term used in

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

to designate the

Last Interglacial The Last Interglacial, also known as the Eemian, was the interglacial period which began about 130,000 years ago at the end of the Penultimate Glacial Period and ended about 115,000 years ago at the beginning of the Last Glacial Period. It cor ...

(130,000-115,000 years ago) and depending on definition, part of the early Last Glacial Period, corresponding to

Marine Isotope Stage 5 Marine Isotope Stage 5 or MIS 5 is a marine isotope stage in the geologic temperature record, between 130,000 and 80,000 years ago. Sub-stage MIS 5e corresponds to the Last Interglacial, also called the Eemian (in Europe) or Sangamonian (in No ...

(~130-80,000 years ago). While often historically considered equivalent in scope to MIS 5, it is now often used in a more narrow sense to refer to the Last Interglacial only (corresponding to MIS 5e and the European Eemian). It preceded the Wisconsinan (Wisconsin) Stage and followed the Illinoian Stage in

Definition

The Sangamonian Stage, originally the Sangamon interglacial stage, is defined on the basis of the Sangamon Soil, a

paleosol In Earth science, geoscience, paleosol (''palaeosol'' in Great Britain and Australia) is an ancient soil that formed in the past. The definition of the term in geology and paleontology is slightly different from its use in soil science. In geo ...

, which is developed in contemporaneous

colluvium Colluvium (also colluvial material or colluvial soil) is a general name for loose, unconsolidated sediments that have been deposited at the base of hillslopes by either rainwash, Sheet erosion , sheetwash, slow continuous downslope creep, or a va ...

and older 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 loesses and overlain by Wisconsinan loesses or tills. Although originally described from water wells in northwestern

Sangamon County, Illinois Sangamon County is a county located near the center of the U.S. state of Illinois. According to the 2020 census, it had a population of 196,343. Its county seat and largest city is Springfield, the state capital. Sangamon County is inclu ...

, the current type sections for the Sangamon Stage are the Rochester section in eastern Sangamon County and the Chapman section in

Morgan County, Illinois Morgan County is a County (United States), county located in the U.S. state of Illinois. According to the 2020 United States census, 2020 census, it had a population of 32,915. Its county seat is Jacksonville, Illinois, Jacksonville. Morgan Co ...

. In the Rochester Section, the Sangamon Soil is developed in Sangamonian

colluvial Colluvium (also colluvial material or colluvial soil) is a general name for loose, unconsolidated sediments that have been deposited at the base of hillslopes by either rainwash, sheetwash, slow continuous downslope creep, or a variable combina ...

sediments, called “accretion gley”, that accumulated contemporaneously with the development of the Sangamon Soil. In the Rochester section, the Sangamon Soil is developed directly in Illinoian glacial till and overlain by Roxana Silt, the oldest of the two regional Wisconsinan loesses.Willman, H.B., and J.C. Frye, 1970, ''Pleistocene Stratigraphy of Illinois.'' Bulletin no. 94, Illinois State Geological Survey, Champaign, Illinois.

Correlations

In its typical and broadest usage, the Sangamonian Stage is equivalent to all of Marine isotope stage 5 between 75,000 and 125,000 BP.McKay III, E.D., R.C. Berg, A.K. Hansel, T.J. Kemmis, and A.J. Stumpf, 2008, ''Quaternary Deposits and History of the Ancient Mississippi Valley.'' North-Central Illinois, Guidebook for the 51st Midwest Friends of the Pleistocene Field Trip, Streator, Illinois, May 13-15, 2005: Illinois State Geological Survey, Guidebook 35, 98 p.Hansel, A.K. and E.D. McKay, in press, Quaternary Period, in D.R. Kolata, ed., The Geology of Illinois. Illinois State Geological Survey, Urbana, Illinois.Fulton, R.J., P.F. Karrow, P. LaSalle, and D.R. Grant, 1984, ''Summary of Quaternary stratigraphy and history, Eastern Canada'', in R. J Fulton, ed., p. 193-210, ''Quaternary Stratigraphy of Canada — A Canadian Contribution to IGCP Project 24'', Geological Survey of Canada Paper, no. 84-10. Although it includes the same time span, the Sangamonian Stage (''sensu lato'') is not temporally equivalent to the

Eemian The Last Interglacial, also known as the Eemian, was the interglacial period which began about 130,000 years ago at the end of the Penultimate Glacial Period and ended about 115,000 years ago at the beginning of the Last Glacial Period. It cor ...

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

. In its much less common usage, the Sangamonian Stage (''sensu stricto'') is equivalent to Marine Isotope Substage 5e and the Eemian. In case of this usage, Marine Isotope Substages 5a, 5b, 5c, and 5d are collectively referred to as the Eowisconsinan Stage.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. In its broadest sense (sensu lato), the Sangamonian Stage precedes the Wisconsinan (Wisconsin) Stage and follows the Illinoian Stage in North America.Willman, H.B., and J.C. Frye, 1970, ''Pleistocene Stratigraphy of Illinois.'' Bulletin no. 94, Illinois State Geological Survey, Champaign, Illinois. Research concerning the age and degree of development of the Sangamon Soil demonstrates that it actively developed, at the least, over all of Marine Isotope Stage 5, which is a period of time from 125,000 to 75,000 BP.Curry, B.B., and M.J. Pavich, 1996, ''Absence of Glaciation in Illinois during Marine Isotope Stages 3 through 5.'' Quaternary Research. v. 46, no. 1, p. 19–26.Grimley, D.A., L.R. Follmer, R.E. Hughes, and P.A. Solheid. 2003, ''Modern, Sangamon and Yarmouth soil development in loess of unglaciated southwestern Illinois.'' Quaternary Science Reviews. 22 no. 2-4, p. 225–244. Unlike Europe, the development of ice sheets in

Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...

was limited during Marine Isotope Substages 5b, 5c, and 5b and either completely disappeared or were greatly reduced in size during Marine Isotope Substage 5a. Clague, J.J., D.J. Easterbrook, O.L. Hughes, and J.V. Mathews, 1992, The ''Sangamonian and Early Wisconsinan Stages in western Canada and Northwestern United States.'' in Clark, P. U., and Lea, P. D., p. 253-268, The Last Interglacial-Glacial Transition in North America. Special Paper no. 270, p. 171–184. Geological Society of America, Boulder, Colorado. Lamothe, M., M. Parent, and W.W. Shilts, 1992, ''Sangamonian and early Wisconsinan events in the St. Lawrence lowland and Appalachians of southern Québec, Canada.'' in P.U. Clark and P.D. Lea, eds., p. 171-184, The Last Interglacial-Glacial Transition in North America. Special Paper no. 270, p. 171–184. Geological Society of America, Boulder, Colorado. Because of the continuous development of the Sangamonian Soil in the Midwest and the limited development of ice sheets in North America during this marine isotope stage, the Sangamonian Stage, unlike the Eemian in Europe, is regarded as encompassing all of Marine Isotope Stage 5.

Dates

The start of the Sangamonian Stage is constrained by

optically stimulated luminescence In physics, optically stimulated luminescence (OSL) is a method for measuring doses from ionizing radiation. It is used in at least two applications: * Luminescence dating of ancient materials: mainly geological sediments and sometimes fired pot ...

(OSL) dates obtained from fluvial deposits of the Pearl Formation and Illinoian glacial tills of the Glasford Formation, which fill an ancient and buried

Mississippi River The Mississippi River is the main stem, primary river of the largest drainage basin in the United States. It is the second-longest river in the United States, behind only the Missouri River, Missouri. From its traditional source of Lake Ita ...

valley in north-central Illinois. The age of fluvial sediments overlying the youngest glacial till (Radnor Member) of the Glasford Formation yield optically stimulated luminescence (OSL) dates that averaged 131,000 BP.McKay, E.D., 2007
''Six Rivers, Five Glaciers, and an Outburst Flood: the Considerable Legacy of the Illinois River.''
Proceedings of the 2007 Governor's Conference on the Management of the Illinois River System: Our continuing Commitment, 11th Biennial Conference, Oct. 2-4, 2007, 11 p.McKay, E.D., and R.C. Berg, 2008

Geological Society of America Abstracts with Programs, Vol. 40, No. 5, p. 78 wit
powerpoint presentation
/ref> These OSL dates demonstrate that the Illinoian Stage ended and the Sangamonian Stage started about 125,000 BP. These dates refute older dates, i.e. between 220,000 and 450,000 BP, given by older publicationsHintze, L.F., 1973, ''Geologic History of Utah.'' Brigham Young University Research Studies, Geology. v. 20, Part 3, no. 8.Ericson D.B., and G. Wollin, 1968, Pleistocene Climates and Chronology in Deep-Sea Sediments. Science. v. 162, no. 3859, p. 1227-1234.Wornardt. W.W., and P.R. Vail, 1991, Revision of the Plio-Pleistocene Cycles and their Application to Sequence Stratigraphy and Shelf and Slope Sediments in the Gulf of Mexico. Gulf Coast Association of Geological Societies Transactions. v. 41, p. 719-744. for the start of the Sangamonian Stage.

Events

The

steppe bison The steppe bison (''Bison'' ''priscus'', also less commonly known as the steppe wisent and the primeval bison) is an extinct species of bison which lived from the Middle Pleistocene to the Holocene. During the Late Pleistocene, it was widely dist ...

(''Bison priscus'') migrated into the heartlands of North America from Alaska at the beginning of the Sangamonian, giving rise to the giant long-horned bison '' Bison latifrons'' (which is first known from the Snowmass site in Colorado, dating to around 120,000 years ago) and ultimately all North American bison species, and marking the beginning of the

Rancholabrean The Rancholabrean North American Land Mammal Age on the geologic timescale is a North American faunal stage in the North American Land Mammal Ages chronology (NALMA),Sanders, A.E., R.E. Weems, and L.B. Albright III (2009) Formalization of the mid- ...

faunal age in North America. Also the Sangamonian the

American lion The American lion (''Panthera atrox'' (), with the species name meaning "savage" or "cruel", also called the North American lion) is an extinct pantherine cat native to North America during the Late Pleistocene from around 129,000 to 12,800 y ...

(''Panthera atrox'') appeared and become widespread across North America, having descended from populations of the Eurasian cave lion (''

Panthera spelaea ''Panthera spelaea'', commonly known as the cave lion (or less commonly as the steppe lion), is an extinct ''Panthera'' species that was native to Eurasia and northwest North America during the Pleistocene epoch. Genetic analysis of ancient DNA ...

'') that had migrated into Alaska during the preceding Illinoian.

References

External links

*Muhs, D.R., 2006
''Last Interglacial: Timing and Environment (LITE).''
U.S. Geological Survey, U.S. Department of the Interior, Denver, Colorado. *Subcommission on Quaternary Stratigraphy, nd

(2007), Department of Geography, University of Cambridge, Cambridge, England. {{Continental Glaciations Glaciology of the United States Middle Pleistocene Pleistocene geochronology Pleistocene North America Pleistocene United States Geology of Illinois Interglacials Marine isotope stages