The Earth's youngest period, the Quaternary, includes the last 2–3 million years and is characterized by several glaciations and warmer interglacial intervals. The cause of the climatic changes is probably to be found in the Earth's orbital parameters, which result in lower summer insolation in the northern hemisphere, which in turn leads to glaciations.
The youngest Quaternary ice age started about 115,000 years ago. After a series of long time oscillations, the ice front reached its maximum in western Denmark, northern Germany and Poland c. 23,000 calendar years ago. At that time, Sweden was completely covered by the inland ice sheet. A pronounced climatic change started the final deglaciation c. 22,000 years ago.
In the beginning, the ice retreat was slow due to temporarily cold phases. About 11,500 calendar years ago the inland ice sheet withdraw from its marginal zone Nyköping–Motala–Skövde–Dals Ed, and about 1,500 years later the last remnants of the inland ice sheet melted away in the interior of northern Sweden.
Most of the Quaternary deposits were formed during and after the latest glaciation. Thus, the Quaternary deposits of Sweden are very young compared to those in non-glaciated areas. The morphology is characterized by the inland ice sheet and the deglaciation processes. Subsequently, the landscape has been reformed to a certain extent by isostatic uplift and wave-washing of the shores. The wind and running water erode the landscape and create new land-forms.
The occurrence and the quality of the Quaternary deposits are of great importance for different purposes:
- physical planning, agriculture, and forestry
- supply of natural resources such as sand and gravel (aggregates), groundwater, energy peat, and minerals
- handling of environmental problems such as radon risk, pollution of ground and groundwater, acidification, and erosion risks (landslides)