Espoo’s soil and bedrock
Espoo features varying types of soil. At any one building site, bare rock as well as soft clay reaching down several metres may be found. In land-use planning, soil conditions have a significant impact on the construction costs of an area.
The landscape is dominated by the diverse features of the soil. Clay valleys, in places expanding into clayey-soil open-land habitats, are typical of Espoo, and they are bordered by rocky hill areas. In clay valleys, soil cover is often over 10 meters thick.
The picture shows a typical cross-section of Espoo’s soil. The soil is stratified over the bedrock (1). The soil cover is thick clay (4) in the structurally controlled valleys of the bedrock. Hilltops have been washed clean of soil covers, exposing the bare rock (6). Here and there, ridge-like formations of coarse soil types (sand (3,5), gravel) can be seen, created as a result of glaciofluvial activity, and in places peat formed on top of the clay underneath can be observed.
A soil map (1:10,000) can be browsed at kartat.espoo.fi.
In the Espoo station area, soil covers of over 40 metres have been penetrated with drilling. The drilling diagram below shows the clay layer marked in blue and the sand layer in yellow.