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More than 1.5 million years ago, during the Pleistocene epoch of the Quaternary, a rapid cooling of the climate occurred. This was the beginning of an ice age. At that time, significant areas of the Northern Hemisphere were covered by an ice sheet. In Europe, it started to grow on the Scandinavian Peninsula. From there, it reached the area of Poland. The Scandinavian ice sheet in our country grew smaller or bigger, depending on the climate warming up or cooling down. The ice sheet grew bigger when the climate became cooler, and grew smaller when the climate warmed up. The glaciations in our country can be divided in diverse ways. They differ according to the names and the number of glaciations. It is a fact that the area of Poland was covered by the ice sheet at least three times.

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Fotografia barwna przedstawiającą fragment lodowca na Grenlandii. Z lewej strony zdjęcia powierzchnia lodu jest praktycznie płaska. ku prawej stronie zaczynają pojawiać się pojawiać bardziej wypukłe, postrzępione formy lodu.

Think about the conditions which must be met for a glacier to form. Do you know why there are currently no glaciers in our country? Write down your conclusions in the section below.

Task 1

Wyjaśnij pojęcie zlodowacenia.

Wyjaśnij pojęcie zlodowacenia.

Watch the animation. It presents the process of glaciation in Poland.

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Nagranie filmowe prezentuje symulację zlodowaceń Polski. Pokazano, że pierwsze zlodowacenie rozpoczęło się w Skandynawii, a następnie objęło cały obszar kraju i zatrzymało się dopiero na górach: Sudetach i Karpatach. Drugie zlodowacenie na zachodzie zatrzymało się na Sudetach, zajęło Bramę Morawską, a na wschodzie dotarło do północnych granic wyżyn. Trzecie objęło swym zasięgiem teren dzisiejszych pojezierzy.

Nagranie filmowe prezentuje symulację zlodowaceń Polski. Pokazano, że pierwsze zlodowacenie rozpoczęło się w Skandynawii, a następnie objęło cały obszar kraju i zatrzymało się dopiero na górach: Sudetach i Karpatach. Drugie zlodowacenie na zachodzie zatrzymało się na Sudetach, zajęło Bramę Morawską, a na wschodzie dotarło do północnych granic wyżyn. Trzecie objęło swym zasięgiem teren dzisiejszych pojezierzy.

Film dostępny na portalu epodreczniki.pl

Nagranie filmowe prezentuje symulację zlodowaceń Polski. Pokazano, że pierwsze zlodowacenie rozpoczęło się w Skandynawii, a następnie objęło cały obszar kraju i zatrzymało się dopiero na górach: Sudetach i Karpatach. Drugie zlodowacenie na zachodzie zatrzymało się na Sudetach, zajęło Bramę Morawską, a na wschodzie dotarło do północnych granic wyżyn. Trzecie objęło swym zasięgiem teren dzisiejszych pojezierzy.

Glaciations in Poland

Ice sheets and glaciers are formed under the following conditions:

• long periods of low (freezing) air temperature;

• snowfalls exceeding snow depletion through melting;

• terrain facilitating the collection of snow (flat land, depressions).

Such conditions were present during the Pleistocene within the region of today’s Scandinavian Peninsula. This is why the ice sheet formed there. At the same time, in our Tatras, Karkonosze Mountains or at Babia Góra mountain glaciers could form, because it is always colder in the mountains than in the lowlands.

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Ilustracja przedstawia współczesną mapę hipsometryczną Europy. Na mapie przedstawiono zasięg zlodowacenia plejstoceńskiego. Zlodowacenie objęło w Europie tereny od Skandynawii po Wielką Brytanię, znaczna część Niemiec oraz praktycznie całą Polskę w obecnych granicach. Na wschodzie zlodowacenie objęło większość Niziny Wschodnioeuropejskiej. Na mapie linią zaznaczono maksymalny zasięg lądolodu skandynawskiego, a tereny które objęło to zlodowacenie, są na mapie zamglone. Obejmują one północną część Europy. Lodowce górskie występują w górach środkowej i południowej części Europy.

Over thousands of years of the Pleistocene, the climate changed, and cooler and warmer periods intertwined. At colder times, the Scandinavian ice sheet expanded. The so‑called glacier transgressionglacier transgressionglacier transgression occurred, where the glacier shifted to neighbouring regions, for example Poland (see map above). The period in which a region is covered by an ice sheet is called glacial periodglacial periodglacial period, or simply ‘glaciation.’ There were four glaciations in Poland: Podlasie Glaciation (the oldest), South Polish Glaciation, Middle Polish Glaciation and North Polish Glaciation (the youngest). These intertwined with warmer times called interglacial periodsinterglacial periodinterglacial periods (i.e. periods in between glaciations), when the ice sheet retreated from our area. It is believed that we live during such an interglacial period now.

The table below presents detailed data of individual glacial and interglacial periods. You will notice that each of these periods has several names used interchangeably by geographers and geologists. The names usually refer to places which the glacier reached within its maximum limits

Glacial land forms in Poland

Several ice sheet transgressions into the area of Poland led to a transformation of the land. Diverse land forms appeared as a result of erosive and accumulative actions of mountain glaciers and continental glaciers (ice sheets).
Erosive action of ice sheets means:

• destruction of the ground with rock material transported by the glacier and the water flowing underneath;

• destruction of the ground due to the pressure of moving ice (mainly in the mountains);

• mechanical weathering (mainly due to frost) of rocks in the vicinity of the glacier.

Wide U‑shaped mountain valleys – for example the Chochołowska Valley or the Kościeliska Valley in the Tatras – were carved by icy tongues and their water. The slopes became covered with layers of weathered rock – stone runs. On the lowlands in front of the ice sheet wide ice‑marginal valleys with mighty rivers were formed. Also on the lowlands, subglacial waters carved deep, long and narrow depressions called troughsglacial troughtroughs, which later filled up with water, forming ribbon lakes.

Accumulative action of glaciers means depositing rock material at different places around the glacier. This led to the existence of undulated terrain forms – moraines, e.g. terminalterminal moraineterminal, flutedfluted morainefluted, and laterallateral morainelateral and medialmedial morainemedial in the mountains. In the lowlands, the ice sheet left erratic boulderserratic bouldererratic boulders, i.e. randomly distributed, single blocks of rock of different sizes. Wide, flattened, sandy plains called sandurssandursandurs were also formed there.

Today’s existence of post‑glacial forms depends on the time of the glacier’s retreat from a certain location. Our last glaciation – North Polish – ended ca. 10 thousand years ago, and the extent of this particular glacial period determines the areas with the greatest numbers of post‑glacial forms.

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Ilustracja przedstawia mapę Polski. Na mapie przedstawiono wybrane formy polodowcowe. Na północy w rejonie pojezierzy biegnie nieregularny pas obrazujący sandry. Wzdłuż rzek i w pasie pobrzeży występują pradoliny. Przerywanymi liniami oznaczono moreny czołowe. Układają się one równoleżnikowo na całym obszarze mapy. Zaznaczono rownież maksymalny zasięg zlodowacenia, biegnie on równoleżnikowo na południu Polski wzdłuż Przedgórza Sudeckiego i Podgórza Karpackiego.

Young glacial and old glacial landforms

Post‑glacial forms exist almost over the entire area of Poland. However, their condition differs according to regions. Post‑glacial landforms in the best condition can be seen in the lake zones and along the coast, as these are the areas where the last North Polish glaciation reached. There, we talk about young glacial landformyoung glacial landformyoung glacial landform characterised by undulation and numerous post‑glacial forms, such as: moraines, lakes, sandurs, eskers, kames, drumlins, etc.

Old glacial ladformsold glacial landformOld glacial ladforms are found south of lake districts. These include mainly the Middle‑Poland Lowlands and a strip of highlands. This was the foreground of the last glaciation, the so‑called periglacial zoneperiglacial zoneperiglacial zone. Its cold climate resulted e.g. in intensive frost weathering of rocks, as well as other processes that take place under frozen ground conditions (permafrost). Together, all the geological processes of the periglacial zone led to equalisation of the earlier post‑glacial landforms. At the same time, other forms, typical for the zone, occurred: stone runs, loess layers, inland dunes.

Summary

• Young glacial landforms are characterised by significant undulation with numerous forms such as lakes, ice‑marginal valleys, sandurs, terminal moraines, fluted moraines, and other elevations.

• The current landscape of Poland has been largely shaped by an ice sheet.

• In our region, we had four glaciations (glacial periods), with the last, North Polish Glaciation having the greatest impact on the present shape of the land.

• The North Polish Glaciation ended only 10 thousand years ago and produced young glacial landforms in lake districts and along some sections of the cost.

• The old glacial landscape is present mostly on the Middle‑Poland Lowlands, primarily with plains intersected with ice‑marginal valleys, moraine ridges and inland dunes.

• In the mountains, mountain glaciers were present, forming e.g. wide U‑shaped valleys or cirques, which nowadays are often lakes filled with water.

Keywords

glacial period, interglacial period, moraines, ice sheet, ice‑marginal valleys

Glossary