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The course of glaciation in Poland

Ice sheets and glaciers form under the following conditions:

• prolonged low (below 0 degrees Celsius) air temperatures;

• snowfall larger than its loss through melting;

• landforms enabling accumulation of snow (flat or concave landscape areas).

Over thousands of years of the Pleistocene, the climate changed, as cooler periods interspersed with warmer ones. When it was relatively cooler over a long period of time, the Scandinavian Ice Sheet increased its size. The ice slid over the neighbouring areas, including Poland (see map above) in the process of so called ice sheet advanceice sheet advanceice sheet advance. The period when a particular area has been covered by an ice sheet is called a glacial, glaciation or simply ice age. In Poland there were four glaciations: Podlaskie (corresponding temporarily to Elbe glaciation in Northern Europe and Beestonian Stage in the British Isles) (the oldest), South Polish (Elster or Anglian Stage), Middle Polish (Saalian) and North Polish (Vistulian or Weichselian) (the most recent). Between them there were warmer periods called interglacials (that is periods between glaciations), when the ice sheet retreated from our area. It is believed that currently we observe such an interglacial.

In the table below you can find detailed data on each of the glacials and interglacials. Note that each of these periods has a few names used by geographers and geologists interchangeably. All of these names relate to the locations reached by the ice sheet in its maximum advance.

Glacial landforms in Poland

Several advances of the ice sheet on the territory of Poland have transformed its landscape. Numerous landforms emerged as a result of erosion and deposition by mountain and continental glaciers (ice sheets).
Glacial erosion is:

• abrasion of the glacier bed by the rock debris carried by the glacier and the water flowing underneath;

• erosion of the bed caused by the sheer pressure of the moving ice (mostly in the mountains);

• physical erosion (mostly by freeze‑thaw weathering) of the rocks near the glacier.

Wide U‑shaped mountain valleys – e.g. Chochołowska Valley or Kościeliska Valley in Tatra Mountains – have been carved by valley glaciers and waters flowing from them. The slopes have accumulated layers of weathered rocks, so called stone runsstone runstone runs. On lowlands, in front of the ice sheet margin, wide meltwater valleys, so called ice‑marginal valleysice‑marginal valleyice‑marginal valleys have developed, filled by large rivers. Also on lowlands, glacial meltwaters have carved deep, long and narrow hollows called tunnel valleystunnel valleytunnel valleys, which were later filled by water to form ribbon lakesribbon lakeribbon lakes.

Glacial deposition is accumulation of rock debris in various places around the glacier. This process has lead to the formation of, among others, undulating landscape forms – moraines, e.g. terminalterminal moraineterminal, groundground moraineground, and in the mountains also laterallateral morainelateral and medialmedial morainemedial. On lowlands, the ice sheet has left behind erraticserraticerratics that is scattered pieces of rocks varying in size. There have also been formed large flat sandy outwash plains also called sandurssandursandurs.

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Zdjęcie przedstawia Dolinę Chochołowską – najdłuższą i największą dolinę w polskich Tatrach. W górnej części doliny dominują formy geologiczne wytworzone przez lodowiec. Zbocza gór porośnięte są lasem - roślinność zanika wraz ze wzrostem wysokości. W oddali kolejne tatrzańskie szczyty.

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Zdjęcie przedstawia pagórkowaty teren Pojezierza Suwalskiego usłany głazami narzutowymi.

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Zdjęcie przedstawia jezioro Gopło, które jest rynnową formą polodowcową. Rynnowaty podłużny kształt jeziora jest ukazany na zdjęciu. Brzegi jeziora porośnięte są drzewami ,wśród których są dachy domów.

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Zdjęcie ukazuje pagórkowaty teren Wzgórz Trzebnickich będących przykładem moreny czołowej. Wzgórza pokryte są polami uprawnymi, na których są ślady po przejeździe maszyn rolniczych. W oddali las.

Young and old glacial landscapes.

Nowadays, glacial landforms can be found almost all over Poland. However, in various regions, they have remained in various condition. Glacial landforms in its best form can be found in lake districts, because these were the areas reached by the last North Polish glaciation. The landscape there is referred to as young glacial landscapeyoung glacial landscapeyoung glacial landscape, characterised by strongly undulating terrain and numerous glacial landforms such as: moraines, lakes sandurs, eskers, kames, drumlins etc.

South of the lake districts, there are areas of old glacial landscapesold glacial landscapeold glacial landscapes. They include mostly the lowlands (Polish Plain) and the uplands belt. During the last glaciation, this was the area near the edge of the ice sheet that is the periglacial zoneperiglacial zoneperiglacial zone. It had a cold climate, which caused intense weathering of rocks due to freeze‑thaw and other erosive processes occurring under the conditions of permanently frozen ground (permafrost). The combination of geological processes in the periglacial environment resulted in the reworking of the earlier glacial landforms. At the same time, other forms emerged, which are characteristic for this zone: stone runs, loess sedimentsloess sedimentloess sediments, inland dunesinland duneinland dunes.

Summary

• On our territory, we had four glaciations (glacials), of which the North Polish Glaciation had the strongest impact on the present landscape.

• The North Polish Glaciation ended only 10 thousand years ago and shaped the young glacial landscape of the lake districts.

• The young glacial landscape of our lake districts is characterised by strongly undulating terrain with numerous landforms, e.g.: lakes, ice‑marginal valleys, sandurs, terminal and ground moraines as well as other types of hills (eskers, kames, drumlins).

• The old glacial landscape is found mostly on lowlands (Polish Plains), dominated by flat terrain diversified here and there by ice‑marginal valleys, morainic ridges and inland dunes.

Keywords

glaciation, ice‑marginal valleys, stone runs, old glacial landscape, young glacial landscape, glacial period, interglacial, moraine

Glossary