Editing Espoo (section)

=== Bedrock ===
The minerals and structures of the rocky and hilly topography of Espoo were formed about 1880 to 1650 million years ago. Particularly the [[Weichselian glaciation]] has had an effect on the current environment – the continental ice sheet withdrew from what is now Espoo about 13 thousand years ago. The first areas to surface from underneath the sea were the high hills in northern Espoo, such as Mustankorvenkallio.<ref name="kohteet">[http://docplayer.fi/512129-Espoon-arvokkaat-geologiset-kohteet-2006.html ESPOON ARVOKKAAT GEOLOGISET KOHTEET 2006], environmental centre of Espoo. Accessed on 9 November 2017.</ref>{{rp|11}} The numerous smooth cliffs on the seashore and in the archipelago were caused by wear by the continental ice sheet; there are grooves on their surfaces, indicating the direction of the flow of the ice sheet. Icebergs split off from the ice sheet have transported [[glacial erratic]]s,<ref name="kallioperä">[https://web.archive.org/web/20171005140442/http://www.espoo.fi/download/noname/%7B2B0BBBE3-EB71-4278-B7AA-63F450E6D262%7D/78907 Espoon kallioperän synty], environmental centre of Espoo. Accessed on 5 November 2017.</ref> including those in Kunnarla, Soukka and Suomenoja.

Main rock types in the Espoo bedrock include [[gneiss]], [[migmatite]], [[granite]], [[gabbro]], [[amphibolite]] and [[mica schist]]. Rare [[orbicular granite]] can be found in Nuuksio, the deposit is internationally valuable.<ref name="kohteet"/> At many places there are thick layers of [[clay]] on top of the bedrock, and fields were plowed onto clay-covered valleys. The thickness of the clay layers was mainly formed in the [[Baltic Ice Lake]] and the [[Yoldia Sea]].<ref name="kohteet"/>{{rp|12}} The effect of the bedrock on the traditional Espoo natural landscape was significant; high and steep cliffs stand up from shallowly waving fields. The oblong lakes in northern Espoo are located in valleys in the bedrock. The formation of the bedrock has determined the shapes of the coastline, such as Espoonlahti and Laajalahti. Because of upthrust, paludification of forests and overgrowth of lakes, [[bog]]s and layers of [[peat]] have formed on top of the clay at some places.<ref name="kallioperä"/>