Editing Brittany (section)

===Geology===
[[File:Bretagne Finistere PointeduRaz15119.jpg|thumb|The [[Pointe du Raz]], one of the westernmost extents of both Brittany and Metropolitan France]]
The Breton peninsula appeared during the [[Cadomian Orogeny]], which formed its northern coastline, between [[Guingamp]] and [[Fougères]]. The southern part emerged during the [[Hercynian orogeny]]. At the same time, an intense volcanic activity left large quantities of [[granite]]. Between the Cadomian and Hercynian periods, the region was submerged several times and the sea left [[fossil]]s and [[sedimentary rock]]s, mostly [[schist]] and [[sandstone]]. Because of the absence of [[limestone]], soils in Brittany are usually acid.

The [[Armorican massif]] straightened and flattened several times during the formation of the [[Pyrenees]] and the [[Alps]]. Changes in sea levels and climate led to a strong erosion and to the formation of more [[sedimentary rock]]s. [[Metamorphism]] is responsible for the distinctive local blue schist and for the rich [[subsoil]] of the [[Groix|Groix island]], which comprises [[glaucophane]] and [[epidote]].<ref name="geology">{{cite web|url=http://www.bretagne-environnement.org/Sous-sol/Le-contexte-breton/Histoire-geologique|title=L'histoire géologique de la Bretagne|editor=Portail de l'information environnementale en Bretagne|author=Emmanuèle Savelli|archive-url=https://web.archive.org/web/20130320132724/http://www.bretagne-environnement.org/Sous-sol/Le-contexte-breton/Histoire-geologique|archive-date=20 March 2013}}</ref>

During the [[Quaternary]] glaciations, Brittany was covered by [[loess]] and rivers started to fill the valleys with alluvial deposits. The valleys themselves were a result of a strong tectonic activity between the [[African Plate|African]] and the [[Eurasian Plate]]. The present Breton landscape did not acquire its final shape before one million years ago. The Breton subsoil is characterised by a huge amount of [[fracture (geology)|fractures]] that form a large [[aquifer]] containing several millions square meters of water.<ref name="geology"/>