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.This period of time is equivalent to all of Marine Isotope Stage 5 and the combined Eemian period and early part of the Weichselian glaciation in Europe. Less commonly, the Sangamonian Stage is restricted to the period between 122,000 and 132,000 BP, which is equivalent to Marine Oxygen Isotope Substage 5e and the Eemian period of Europe. It preceded the Wisconsinan (Wisconsin) Stage and followed the Illinoian Stage in North America.
The Sangamonian Stage, originally the Sangamon interglacial stage, is defined on the basis of the Sangamon Soil, a paleosol, which is developed in contemporaneous colluvium and older glacial tills and loesses and overlain by Wisconsinan loesses or tills. Although originally described from water wells in northwestern Sangamon County, Illinois, the current type sections for the Sangamon Stage are the Rochester section in eastern Sangamon County and the Chapman section in Morgan County, Illinois. In the Rochester Section, the Sangamon Soil is developed in Sangamonian colluvial 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.
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.Although it includes the same time span, the Sangamonian Stage (sensu lato) is not temporally equivalent to the Eemian in Europe. 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. In its broadest sense (sensu lato), the Sangamonian Stage precedes the Wisconsinan (Wisconsin) Stage and follows the Illinoian Stage in North America.
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.Unlike Europe, the development of ice sheets in Canada 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. 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.
The start of the Sangamonian Stage is constrained by optically stimulated luminescence (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 valley in north-central Illinois. The age of fluvial sediments overlying the youngest glacial till (Radner Member) of the Glasford Formation yield optically stimulated luminescence (OSL) dates that averaged 131,000 BP.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 publications for the start of the Sangamonian Stage.
The Pleistocene is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the world's most recent period of repeated glaciations. The end of the Pleistocene corresponds with the end of the last glacial period and also with the end of the Paleolithic age used in archaeology.
Loess is a clastic, predominantly silt-sized sediment that is formed by the accumulation of wind-blown dust. Ten percent of the Earth's land area is covered by loess or similar deposits.
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 corresponds to Marine Isotope Stage 5e. Although sometimes referred to as the "last interglacial", it was the second-to-latest interglacial period of the current Ice Age, the most recent being the Holocene which extends to the present day. The prevailing Eemian climate was, on average, around 1 to 2 degrees Celsius warmer than that of the Holocene. During the Eemian, the proportion of CO
2 in the atmosphere was about 280 parts per million.
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.
The Anglian Stage is the name used in the British Isles for a middle Pleistocene glaciation. It precedes the Hoxnian Stage and follows the Cromerian Stage in the British Isles. The Anglian Stage is correlated to Marine Isotope Stage 12, which started about 478,000 years ago and ended about 424,000 years ago.
The Cromerian Stage or Cromerian Complex, also called the Cromerian, is a stage in the Pleistocene glacial history of north-western Europe, mostly occurring more than half a million years ago. It is named after the East Anglian town of Cromer in England where interglacial deposits that accumulated during part of this stage were first discovered. The stratotype for this interglacial is the Cromer Forest Bed situated at the bottom of the coastal cliff near West Runton. The Cromerian stage preceded the Anglian and Elsterian glacials and show an absence of glacial deposits in western Europe, which led to the historical terms Cromerian interglacial and the Cromerian warm period. It is now known that the Cromerian consisted of multiple glacial and interglacial periods.
The Hoxnian Stage was a middle Pleistocene stage of the geological history of the British Isles. It was an interglacial which preceded the Wolstonian Stage and followed the Anglian Stage. It is equivalent to Marine Isotope Stage 11(MIS 11). Marine Isotope Stage 11 started 424,000 years ago and ended 374,000 years ago. The Hoxnian is divided into sub-stages Ho I to Ho IV.
The Wolstonian Stage is a middle Pleistocene stage of the geological history of Earth that precedes the Ipswichian Stage and follows the Hoxnian Stage in the British Isles. The Wolstonian Stage apparently includes three periods of glaciation. The Wolstonian Stage is temporally analogous to the Warthe Stage and Saalian Stage in northern Europe and the Riss glaciation in the Alps, and temporally equivalent to all of the Illinoian Stage and the youngest part of the Pre-Illinoian Stage in North America. It is contemporaneous with the North American Pre-Illinoian A, Early Illinoian, and Late Illinoian glaciations. The Wolstonian Stage is equivalent to Marine Isotope stages 6 through 10. It started 352,000 years ago and ended 130,000 years ago.
The Kansan glaciation or Kansan glacial was a glacial stage and part of an early conceptual climatic and chronological framework composed of four glacial and interglacial stages.
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 the Sangamonian Stage and follows the Pre-Illinoian Stage in North America. The Illinoian Stage is defined as the period of geologic time during which the glacial tills and outwash, which comprise the bulk of the Glasford Formation, accumulated to create the Illinoian Glacial Lobe. It occurs at about the same time as the penultimate glacial period.
The Yarmouthian stage and the Yarmouth Interglacial were part of a now obsolete geologic timescale of the early Quaternary of North America.
The Beestonian Stage is an early Pleistocene stage used in the British Isles. It is named after Beeston Cliffs near West Runton in Norfolk where deposits from this stage are preserved.
The Pre-Pastonian Stage or Baventian Stage, is the name for an early Pleistocene stage used in the British Isles. It precedes the Pastonian Stage and follows the Bramertonian Stage. This stage ended 1.806 Ma at the end of Marine Isotope Stage 65. It is not currently known when this stage started. The Pre-Pastonian Stage is equivalent to the Tiglian C4c Stage of Europe and the Pre-Illinoian J glaciation of the early Pre-Illinoian Stage of North America.
Stadials and interstadials are phases dividing the Quaternary period, or the last 2.6 million years. Stadials are periods of colder climate while interstadials are periods of warmer climate.
Marine isotope stages (MIS), marine oxygen-isotope stages, or oxygen isotope stages (OIS), are alternating warm and cool periods in the Earth's paleoclimate, deduced from oxygen isotope data reflecting changes in temperature derived from data from deep sea core samples. Working backwards from the present, which is MIS 1 in the scale, stages with even numbers have high levels of oxygen-18 and represent cold glacial periods, while the odd-numbered stages are troughs in the oxygen-18 figures, representing warm interglacial intervals. The data are derived from pollen and foraminifera (plankton) remains in drilled marine sediment cores, sapropels, and other data that reflect historic climate; these are called proxies.
An interglacial period 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 interglacial began at the end of the Pleistocene, about 11,700 years ago.
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.
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, called the Eemian or Ipswichian, covers the last major interglacial period before the Holocene, which extends to the present day. Interglacial periods which occurred during the Pleistocene are investigated to better understand present and future climate variability. Thus, the present interglacial, the Holocene, is compared with MIS 5 or the interglacials of Marine Isotope Stage 11.
The Penultimate Glacial Period (PGP) is the glacial period that occurred before the Last Glacial Period. It began ~194,000 years ago, and ended ~135,000 years ago with the beginning of the Eemian interglacial. It roughly coincides with Marine Isotope Stage 6 and the Illinoian Stage. The Penultimate Glacial Period is one of a series of glacial and interglacial periods of the Quaternary ice age. The Quaternary ice age began 2.58 million years ago and is ongoing. It began with the beginning of the periodic ice sheet advances and retreats in the Northern Hemisphere, including the Laurentide Ice Sheet, the Cordilleran Ice Sheet, and the Greenland ice sheet. The Quaternary ice age is part of an even longer ice age called the Late Cenozoic Ice Age. It began 33.9 million years ago and is also ongoing. It began with the formation of the Antarctic Ice Cap.
The Don Glaciation, also known as the Donian Glaciation and the Donian Stage, was the major glaciation of the East European Plain, 0.5–0.8 million years ago, during the Cromerian Stage of the Middle Pleistocene. It is correlated to Marine Isotope Stage 16, approximately 650,000 years ago, which globally contained one of the largest glacial volumes of the Quaternary.