On a geological timescale, Earth's climate has gone through considerable changes. Colder periods, during which glaciers covered more land and sea than today, are clled ice ages. The last glacial period, commonly referred to as The ice age, began 115,000 years before present, and ended around 9,700 BC; that is 11,700 years ago.
The Nordic countries were covered by ice during the last Ice Age, until 10,000 BC. The ice has set its mark on the scenery. The Earth's crust was pushed down, and is still rising in modern times, up to one centimetre each year in northern Sweden and Finland. The post-glacial rebound constantly moves the coastline; most modern settlements and farmlands in Sweden and Finland were navigable sea a few thousand years, or even less than 1,000 years ago. The movement is enough for old people to remember a different shoreline. The ice has set other traces in the scenery, such as enormous rocks in otherwise flat terrain and hundred meter high sandy terraces at valley mouths. The fjords of Norway were also created by glacial erosion, though at a longer time scale. The rising land has lifted parts of some fjords above the sea level and in this way created picturesque lakes.
In Norse mythology, the gods Thor and Loki visited the giant Skrymir, who gave them many challenges. Skrymir wagered that Thor, famous for his strength and thirst for beer, could not empty Skrymir's enormous drinking horn in three sips. While Thor took great effort, he failed. Skrymir revealed that he had put the spike of the horn into the sea, to prevent Thor from emptying the horn. However, the sea level had dropped since before he drank.
- 1 High Coast (Höga kusten) (Sweden). A region where post-glacial rebound reaches nearly 1 centimetre a year
- 2 Simo Upthrust Park (Simon Maankohoumapuisto) (Simo, Finland). During the last ice age the kilometers thick ice sheet caused the basement rock to depress. The Bothnian Bay area is the best place on Earth to see how it slowly rises up, nearly one centimeter a year. Eventually this phenomenon known as post-glacial rebound will slowly turn the whole Bothnian Bay into a lake. The Upthrust Park is a collection of sites where one may get some feeling on this fancy phenomenon. Info plates.
- 1 Ice Age trail (Wisconsin, United States). A walking trail with a showcase of geological features.
- 3 Finger Lakes (New York, United States). Eleven north-south lakes.
- 4 Vandresteinen i Stavanger (Travelling boulder in Stavanger). Glacial erratic (or travelling boulder) resting in Rogalandsgaten, Stavanger. Protected by law since 1959 as natural heritage. free.
- 5 Haukalivatnet. Haukalivatnet is a fjord-lake at 50 meters above sea level in Rogaland near mouth of Lysefjorden. Jens Esmark in 1823 realized similarities to moraines near existing glaciers at Jostedalsbreen. Esmark concluded that glaciers had covered large parts of the land. Esmark's discovery were later attributed to or appropriated by Theodor Kjerulf and Louis Agassiz. Geoscientist Jens Esmark in 1824 published an article stating that there was indisputable evidence that Norway and other parts of Europe had previously been covered by enormous glaciers carving out valleys and fjords, in a cold climate caused by changes in the eccentricity of Earth's orbit. Esmark and his travel companion Otto Tank arrived at this insight by analogous reasoning: enigmatic landscape features they observed close to sea level along the Norwegian coast strongly resembled features they observed in the front of a retreating glacier during a mountain traverse in the summer of 1823. free.
- 6 Svelvikryggen (Svelvik ridge) (Svelvik near Drammen). The Svelvik ridge cuts the Drammensfjord almost in two. The ridge is some 50-70 meters high and contains glacial sand and gravel (fluvioglacial gravel from the last Holocene deglaciation). Water has dug a natural strait or canal between the inner and outer Drammensfjord. The great supply of freshwater to the inner Drammensfjord makes the water in deep inner fjord brackish and almost like a lake (a common situation in glacial fjords with shallow tresholds). Surplus water and tide sets up one of Norway's strongest tidal currents in the Svelvik canal. The Svelvik canal is crossed by Norway's shortest ferry trip. The canal is the access to Drammen port, one of Norway's most important. free.
- The South Scandinavian Ra: The Ra is the largest terminal moraine in Southern Scandinavia and Finland. The Ra was created at the one of the last glacial advances around 11,000 years A.D.. The Ra crosses the Scandinavian peninsula roughly between Oslo and Stockholm, then runs around Norway's south coast. Ra is an old Norse word for a ridge of gravel. Terminal moraines are typically mixed material of boulders, pebbles, sand and clay. On the surface, finer particles have been washed off and left course particles like boulders and pebbles. In Norway, the Ra is clearly visible and well-known particularly in Østfold and Vestfold areas around the Oslofjord. Some of Norway's best agricultural land is along the slopes of the Ra. In Vestfold the main road has since prehistory followed the Ra because the highest point of the Ra is naturally dry and stable. In Østfold road E6 runs along the Ra between Halden and Moss (about 60 kilometers).
- 7 Raet National Park. Raet National Park (Norwegian: Raet nasjonalpark) is a national park in Arendal, Tvedestrand and Grimstad in Agder, southeastern Norway. It is partly on short and partly under water, and includes some islands and coastal areas.
- 8 Jomfruland (island). Jomfruland is a elongated island located off the coast at Kragerø in Telemark, Norway. The island is largely made of pebbles and is part of the Ra, the great terminal moraine. Jomfruland shelters the archipelago within. The island and surround sea is protected as a national park.