Quaternary geology

Soil types are formed through a number of different processes. Rock is bleached and eroded, sediments are collected on sea beds, older soil types are regenerated and redeposited. In other words, the soil types that exist today in Sweden have been formed in many different ways – something that has also contributed to the diversity of the soil covering’s properties. In several places the soil types form distinct surface shapes, for example, glaciofluvial eskers.

The Swedish soil types were mostly deposited during and after the last ice age. Many parts of North America and Northern Europe have been covered by ice sheets and therefore have soil types that in many respects resemble Swedish ones. In large parts of the world, however, the soil covering is considerably older and has a completely different character.
    
The composition of the soil is one of the factors that affects which plants and animals can live in a place. The different species of soil also affect how we humans can use the soil. In some areas, the soil is ideal for arable land, while other soils are best used for forestry purposes. Knowledge of soil types is of great importance in, for example, planning for construction and the abstraction of groundwater. The composition of soils also affects how sensitive the ground is to different kinds of pollution. Some soil types can cause problems when there is a risk of them suddenly moving due to landslides or avalanches. Some soil types have properties that make them attractive to mine. For example, the material in glaciofluvial eskers can be extracted for construction and the peat from wetlands can be used as fuel.

In Sweden, almost all soil types were formed in the quaternary era. This period began about 2.5 million years ago and extends to the present. The area of geology that relates to the soil types is therefore often called quaternary geology.