Würm Glaciation
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The Würm glaciation or Würm stage ( or ''Würm-Glazial'', colloquially often also ''Würmeiszeit'' or ''Würmzeit''; cf.
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 g ...
), usually referred to in the literature as the Würm (often spelled "Wurm"), was the last glacial period in the Alpine region. It is the youngest of the major
glaciation A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate be ...
s of the region that extended beyond the Alps themselves. Like most of the other ice ages of the
Pleistocene The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...
epoch, it is named after a river, in this case the Würm in
Bavaria Bavaria, officially the Free State of Bavaria, is a States of Germany, state in the southeast of Germany. With an area of , it is the list of German states by area, largest German state by land area, comprising approximately 1/5 of the total l ...
, a tributary of the Amper. The Würm ice age can be dated to about 115,000 to 11,700 years ago. Sources differ about the dates, depending on whether the long transition phases between the
glacial A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires ...
s 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 i ...
s (warmer periods) are allocated to one or other of those periods. The
average annual temperature Climate is the long-term weather pattern in a region, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorol ...
s during the Würm ice age in the Alpine Foreland were below −3 °C (today +7 °C). That has been determined from changes in the vegetation ( pollen analysis), as well as differences in the facies.


Corresponding glaciations worldwide

The corresponding ice age in North and Central Europe is known as the Weichselian glaciation, after the German name for the
Vistula The Vistula (; ) is the longest river in Poland and the ninth-longest in Europe, at in length. Its drainage basin, extending into three other countries apart from Poland, covers , of which is in Poland. The Vistula rises at Barania Góra i ...
river. Despite the global changes in climate that were responsible for the major glaciations cycles, the dating of the Alpine ice sheet advances does not correlate automatically with the farthest extent of the Scandinavian
ice sheet In glaciology, an ice sheet, also known as a continental glacier, is a mass of glacier, glacial ice that covers surrounding terrain and is greater than . The only current ice sheets are the Antarctic ice sheet and the Greenland ice sheet. Ice s ...
. In North America the corresponding "last ice age" is called the
Wisconsin glaciation The Wisconsin glaciation, also called the Wisconsin glacial episode, was the most recent glacial period of the North American ice sheet complex, peaking more than 20,000 years ago. This advance included the Cordilleran Ice Sheet, which nucleated ...
.Ehlers, J., and Gibbard, P. L.: ''Quaternary Glaciations: Extent and Chronology 2: Part II North America.'' Elsevier, Amsterdam, 2004


Temporal classification

In the
Gelasian The Gelasian is an age in the international geologic timescale or a stage in chronostratigraphy, being the earliest or lowest subdivision of the Quaternary Period/System and Pleistocene Epoch/Series. It spans the time between 2.58 Ma (million y ...
, i.e. at the beginning of the
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), as well as the current and most recent of the twelve periods of the ...
period around 2.6 million years ago, an
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 g ...
began in the northern hemisphere which continues today. Characteristic of such ice ages is the glaciation of the polar caps. After the Gelasian followed the Early, Middle and Late Pleistocene with a succession of several warm and cold periods. The latter are often called "ice ages" or "glacials", the former term often being confused with the overarching ice age period. The warm periods are called "interglacials".
Glacier A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires ...
s repeatedly advanced from the Alps to the northern molasse foreland and left
moraine A moraine is any accumulation of unconsolidated debris (regolith and Rock (geology), rock), sometimes referred to as glacial till, that occurs in both currently and formerly glaciated regions, and that has been previously carried along by a gla ...
s and meltwater deposits behind that are up to several hundred metres thick. Today, the Pleistocene epoch in the Alps is divided into several phases: the '' Biber'', ''
Danube The Danube ( ; see also #Names and etymology, other names) is the List of rivers of Europe#Longest rivers, second-longest river in Europe, after the Volga in Russia. It flows through Central and Southeastern Europe, from the Black Forest sou ...
'', '' Günz'', '' Haslach'', '' Mindel'', '' Riss'' and ''Würm'' glaciations. The greatest ice advance into the Alpine Foreland took place during the Riss glaciation,
cf. The abbreviation cf. (short for either Latin or , both meaning 'compare') is generally used in writing to refer the reader to other material to make a comparison with the topic being discussed. However some sources offer differing or even contr ...
the Saale glaciation in northern Europe. The most recent foreland glaciation, the Würm, did not have such an extensive and solid glacial front. Nevertheless, its
terminal moraine A terminal moraine, also called an end moraine, is a type of moraine that forms at the terminal (edge) of a glacier, marking its maximum advance. At this point, debris that has accumulated by plucking and abrasion, has been pushed by the front e ...
s, which indicate the perimeter of the ice sheet, extend as a single tongue well into the foreland. Whilst they were hemmed in by the high mountainsides of the Alps, once these rivers of ice entered the foreland they often combined to form huge glaciers. The moraines and gravel beds formed in the Würm glaciation are the best preserved, because since then there have been no more similar geological processes. Traces of the ice sheet have not been scoured out by later glaciers or overlaid by their sediments. This allows a more precise dating for the Würm glaciation than for earlier ice ages. The Würm glaciation was preceded by the Eemian, which began about 126,000 years ago and lasted 11,000 years. Then there was a significant slowdown, characterized by occasional fluctuations of several degrees in average temperatures. The various advances and retreats of glaciers associated with these temperature fluctuations, are called "stadials" (periods of relatively low temperatures) and "interstadials" (relatively higher temperatures). The Würm Glacial ended around 11,700 years ago with the beginning of the
Holocene The Holocene () is the current geologic time scale, geological epoch, beginning approximately 11,700 years ago. It follows the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene to ...
. The cold period was followed by another warming which continues today and during which the glaciers are retreating. However, even in the Holocene there have been variations in temperature and ice advances, the last one in the
modern era The modern era or the modern period is considered the current historical period of human history. It was originally applied to the history of Europe and Western history for events that came after the Middle Ages, often from around the year 1500 ...
being the so-called
Little Ice Age The Little Ice Age (LIA) was a period of regional cooling, particularly pronounced in the North Atlantic region. It was not a true ice age of global extent. The term was introduced into scientific literature by François E. Matthes in 1939. Mat ...
. The Holocene is considered an "interglacial" of a larger ice age, since the poles and the high mountain areas are still glaciated.


See also

*
Glacial series The glacial series refers to a particular sequence of landforms in Central Europe that were formed during the Last glacial period, Pleistocene glaciation beneath the ice sheets, along their margins and on their forelands during each glacial advance ...
*
Glaciology Glaciology (; ) is the scientific study of glaciers, or, more generally, ice and natural phenomena that involve ice. Glaciology is an interdisciplinary Earth science that integrates geophysics, geology, physical geography, geomorphology, clim ...


References


Sources

* Roland Walter: ''Geologie von Mitteleuropa''. Schweizerbartsche Verlagsbuchhandlung, Stuttgart, 1992, * René Hantke: ''Eiszeitalter. Band 2: Letzte Warmzeiten, Würm-Eiszeit, Eisabbau und Nacheiszeit der Alpen-Nordseite vom Rhein- zum Rhone-System.'' Ott, Thun, 1980, * Hans Graul, Ingo Schäfer: ''Zur Gliederung der Würmeiszeit im Illergebiet''. Straub, Munich, 1953. (Geologica Bavarica, 18). *Wolfgang Frey, Rainer Lösch: ''Lehrbuch der Geobotanik, Pflanze und Vegetation in Raum und Zeit''. Elsevier Spektrum Akademischer Verlag, *Dirk van Husen: ''Die Ostalpen in den Eiszeiten'', Aus der Geologischen Geschichte Österreichs, Geologische Bundesanstalt Wien, *Rolf K. Meyer, Hermann Schmidt-Kaler: ''Auf den Spuren der Eiszeit südlich von München – östlicher Teil'', Wanderungen in die Erdgeschichte, Vol. 8,


External links

* Karte: {{DEFAULTSORT:Wurm glaciation Pleistocene Ice ages Holocene Geology of the Alps Last Glacial Period