The Yarmouthian stage and the Yarmouth Interglacial were part of a now obsolete

geologic timescale The geologic time scale, or geological time scale, (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochronol ...

of the early

Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million years ...

of North America.

Development

This climatic and chronological framework was composed of four glacial and

interglacial An interglacial period (or alternatively interglacial, interglaciation) is a geological interval of warmer global average temperature lasting thousands of years that separates consecutive glacial periods within an ice age. The current Holocene in ...

stages. It was developed between 1894 and 1909 by geomorphologists and

Quaternary geologists The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million year ...

to subdivide glacial and nonglacial deposits within the United States of America. From youngest to oldest, they were the

Wisconsinian The Wisconsin Glacial Episode, also called the Wisconsin glaciation, was the most recent glacial period of the North American ice sheet complex. This advance included the Cordilleran Ice Sheet, which nucleated in the northern North American Cor ...

Stage (glacial),

Sangamonian The Sangamonian Stage (or Sangamon interglacial) is the term used in North America to designate the last interglacial period. In its most common usage, it is used for the period of time between 75,000 and 125,000 BP.Willman, H.B., and J.C. Frye, 1 ...

(interglacial),

Illinoian 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 ...

(glacial), Yarmouthian (interglacial), Kansan (glacial),

Aftonian 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 ...

(interglacial), and Nebraskan (glacial) stages. The Yarmouthian (Yarmouth) Interglacial was defined first on the basis of "interglacial" sediments encountered in

wells Wells most commonly refers to: * Wells, Somerset, a cathedral city in Somerset, England * Well, an excavation or structure created in the ground * Wells (name) Wells may also refer to: Places Canada *Wells, British Columbia England * Wells ...

dug in southeasterm

Iowa Iowa () is a state in the Midwestern region of the United States, bordered by the Mississippi River to the east and the Missouri River and Big Sioux River to the west. It is bordered by six states: Wisconsin to the northeast, Illinois to the ...

. Later the Yarmouth (Yarmouthian) stage in

Illinois Illinois ( ) is a U.S. state, state in the Midwestern United States, Midwestern United States. Its largest metropolitan areas include the Chicago metropolitan area, and the Metro East section, of Greater St. Louis. Other smaller metropolita ...

was defined on the basis of the

Yarmouth Paleosol Yarmouth may refer to: Places Canada *Yarmouth County, Nova Scotia **Yarmouth, Nova Scotia **Municipality of the District of Yarmouth **Yarmouth (provincial electoral district) **Yarmouth (electoral district) * Yarmouth Township, Ontario *New ...

(Soil) developed in the surface of what were thought at that time to be "Kansan" glacial tills and buried by Illionian glacial tills of the

Glasford Formation Glasford is a village in Peoria County, Illinois, United States. The population was 1,022 at the 2010 census. Glasford is part of the Peoria, Illinois Metropolitan Statistical Area. History Glasford or Glasco as it was called in 1868, was named fo ...

in southeast Iowa and east-central Illinois. At this time, it was incorrectly presumed that the Yarmouth Paleosol formed during a single interglacial stage that separated a younger glacial stage, the Illinoian Glaciation, represented by the sediments of the Glasford Formation in Illinois and the glacial deposits of an older glacial stage, called the "Kansan Glaciation".Flint, R.F., 1957, ''Glacial Geology and the Pleistocene Epoch.'' John Wiley & Sons, New York. 553 p. New YorkAber, J.S., 1991, ''Glaciations of Kansas.'' Boreas. vol. 20, no. 4,pp. 297-314Roy, 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.

Conflicts

Since the Yarmouthian (Yarmouth) interglacial was named, the stratigraphy of

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...

deposits was found to be far more complex than the two glacial tills and one

volcanic ash Volcanic ash consists of fragments of rock, mineral crystals, and volcanic glass, created during volcano, volcanic eruptions and measuring less than 2 mm (0.079 inches) in diameter. The term volcanic ash is also often loosely used t ...

bed on which the Yarmouthian, Kansan, Nebraskan, and Aftonian glacial - interglacial nomenclature was originally based. Detailed research by various geomorphologists and Quaternary geologists 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. 35–49Boellstorff, 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. For example, the so-called "Kansan" glacial sediments in which the Yarmouth Soil developed are now known to date to different periods of glaciation depending on where it is examined within the Midwest and other parts of North America. In addition, fission track dating and

geochemical Geochemistry is the science that uses the tools and principles of chemistry to explain the mechanisms behind major geological systems such as the Earth's crust and its oceans. The realm of geochemistry extends beyond the Earth, encompassing the e ...

analysis demonstrated what was thought to be one

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. Thus, 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, the Yarmouthian (interglacial), Kansan (glacial), Aftonian (interglacial), and Nebraskan (glacial) nomenclature was abandoned by Quaternary geologists North America and merged into the Pre-Illinoian 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.

Reassessment

Because of the flaws with the early conceptual climatic and chronological framework for Midwestern glacial - interglaciations, the Yarmouthian (Yarmouth) Interglacial (Stage) completely lacks any meaning or usefulness in North American glacial - interglacial nomenclature. First, the incorrect presumption that there was only one major ash bed within the Midwestern United States lead to the misclassification of Middle to Early Pleistocene interglacial deposits containing 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 as being the same age. Because it was thought that there was only one significant ash bed, not three of them, any nonglacial deposit containing an ash bed, regardless of its true age, were thought to be the same age. As a result, the nonglacial deposits attributed in the scientific literature as dating to the Yarmouthian (Yarmouth) Interglacial (Stage) consist of an assemblage of sediments deposited during a number of differing interglacial periods, including some dating to 0.60, 1.22, and 2.02 million years ago. An additional problem is that recent research demonstrates that the glacial tills, the Glasford Formation, of the Illinoian Stage are limited in age to Marine Isotope Stage 6.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.
/ref>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> Thus, within Illinois and adjacent parts of Iowa, the Yarmouth Soil (paleosol), which defines the Yarmouthian (Yarmouth) Interglacial (Stage) in Illinois, spans a period of geologic time equivalent to Marine Isotope stages 7, 8, 9, 10, and 11. Elsewhere in North America, as in Illinois, the Yarmouth Soil also has developed over a variable number of multiple glacial - interglacial cycles. Thus, the presumption that the Yarmouth Soil, by which the Yarmouthian (Yarmouth) Interglacial was later defined, represents a single interglacial stage or period has been completely discredited. Also, the "interglacial" deposits used by Leverett to originally define the Yarmouthian (Yarmouth) Interglacial in 1898 actually consist of interbedded glacial tills, diamictons, peats, sands, and silts, that are part of the Kellerville Till Member of the Glasford Formation. Pollen samples and wood recovered from these deposits indicate that the vegetation consisted of a Picea-Larix forest and that climate was full-glacial rather than interglacial during their accumulation.Hallberg, G. R., ed., 1980
''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. Thus, the criteria, i.e. (1.) its sediments being all of the same age, (2.) it consisting of sediments deposited during a single interglacial period, and (3,) as originally defined by Leverett in 1898 consist of interglacial sediments, by which the Yarmouthian (Yarmouth) Interglacial (Stage) was defined and recognized have all been found to be false.

References

External links

*Aber, J.S., 2006

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., 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;

Development

Conflicts

Reassessment

References

External links

See also