Editing Geography of Finland (section)

== Relief and geology ==
===Geology===
{{main|Geology of Finland}}
[[File:Kilpisjärvi, Lapland (52212356347).jpg|thumb|255x255px|Mountainous landscape at [[Kilpisjärvi]]]]
The [[bedrock]] of Finland belong to the [[Baltic Shield]]<ref name="Natenterrang" /> and was formed by a succession of [[orogeny|orogenies]] in [[Precambrian]] time.<ref name="UppslagsFiBERG" /> The oldest rocks of Finland, those of [[Archean]] age, are found in the east and north. These rocks are chiefly [[granite|granitoid]]s and [[migmatite|migmatitic]] [[gneiss]].<ref name="Natenterrang" /> Rocks in central and western Finland originated or came to place during the [[Svecofennian orogeny|Svecokarelian orogeny]].<ref name="Natenterrang" /> Following this last orogeny [[Rapakivi granite]]s [[intrusion (geology)|intruded]] various locations of Finland during the [[Mesoproterozoic]] and [[Neoproterozoic]], specially at [[Åland]] and the southeast.<ref name="Natenterrang" /> So-called [[Jotnian|Jotnian sediment]]s occur usually together with Rapakivi granites.<ref name="Korjaetal1993">{{cite journal |last1=Korja |first1=A. |last2=Korja |first2=T.|last3=Luosto |first3=U.|last4=Heikkinen |first4=P. |year=1993 |title= Seismic and geoelectric evidence for collisional and extensional events in the Fennoscandian Shield – implications for Precambrian crustal evolution |journal=[[Tectonophysics (journal)|Tectonophysics]] |volume=219 |issue=1–3 |pages=129–152 |doi=10.1016/0040-1951(93)90292-r}}</ref> The youngest rocks in Finland are those found in the northwestern arm which belong to [[Scandinavian Caledonides]] that assembled in [[Paleozoic]] times.<ref name="UppslagsFiBERG" /> During the [[Caledonian orogeny]] Finland was likely a sunken [[foreland basin]] covered by sediments, subsequent uplift and erosion would have eroded all of these sediments.<ref>{{cite journal |last1=Murrell |first1=G.R. |last2=Andriessen |first2=P.A.M. |date=2004 |title=Unravelling a long-term multi-event thermal record in the cratonic interior of southern Finland through apatite fission track thermochronology |journal=Physics and Chemistry of the Earth, Parts A/B/C |volume=29 |issue=10 |pages=695–706 |doi= 10.1016/j.pce.2004.03.007}}</ref>

===Relief and hydrography===
{{See also|List of islands of Finland}}
[[File:Svedjehamnin näkötorni 04.06.2016.jpg|thumb|An aerial view of the [[Kvarken Archipelago]]]]
About one third of Finland lies below 100 m, and about two thirds lies under 200 m.<ref name="Natenterrang" /> Finland can be divided into three topographical areas; the coastal landscapes, the [[Finnish Lakeland|interior lake plateau]] also known as Finnish lake district and [[Upland Finland]].<ref name="Natenterrang">{{cite web |url=https://www.ne.se/uppslagsverk/encyklopedi/l%C3%A5ng/finland?i_h_word=%25C3%25B6sterland |title=Finland: Terrängformer och berggrund |last1=Behrens |first1=Sven |last2=Lundqvist|first2=Thomas|author-link2=Thomas Lundqvist (geologist) |website=[[Nationalencyklopedin]] |publisher=Cydonia Development |access-date=November 30, 2017 |language=sv}}</ref> The coastal landscapes are made up mostly of plains below 20 m. These plains tilt gently towards the sea so that where its irregularities surpasses sea-level groups of islands like the [[Norra Kvarken|Kvarken Archipelago]] or the [[Åland|Åland Islands]] are found.<ref name="Natenterrang" /> Åland is connected to the Finnish mainland by a shallow submarine plateau that does not exceed 20 m in depth.<ref name="UppslagsFiUniv">{{cite web |url=http://uppslagsverket.fi/sv/sok/view-103684-Aaland |title=Åland |last=Lindberg |first=Johan  |date=May 26, 2016 |website=[[Uppslagsverket Finland]] |access-date=November 30, 2017 |language=sv}}</ref> Next to the [[Gulf of Bothnia]] the landscape of Finland is extremely flat with height differences no larger than 50 m.<ref name="Rudberg">{{cite book |last=Rudberg |first=Sten |author-link=Sten Rudberg |date=1960 |title=Geography of Norden |chapter=Geology and Morphology |pages=27–40|editor-last=Somme|editor-first=Axel|editor-link=Axel Sømme }}</ref> This region called the [[Ostrobothnian Plain]] extends inland about 100&nbsp;km and constitute the largest plain in the [[Nordic countries]].<ref name="Rudberg" />

The interior lake plateau is dominated by undulating hilly terrain with valley to top height differences of 100 or less and occasionally up to 200 m.<ref name="Natenterrang" /><ref name="Rudberg" /> Only the area around the lakes [[Pielinen]] and [[Lake Päijänne|Päijänne]] stand with a subtly more pronounced relief.<ref name="Rudberg" /> The relief of the interior lake plateau bears some resemblance to the Swedish [[Norrland terrain]].<ref name="Natenterrang" /> Upland Finland and areas higher than 200 m are found mostly in the north and east of the country where hills and mountains exceed 500 m in height in these regions.<ref name="Rudberg" /> [[Inselberg#Geology|Inselberg plains]] are common in the northern half of the country.<ref>{{cite journal |last1=Ebert |first1=K. |last2=Hall |first2=A. |last3=Hättestrand |first3=C. |last4= Alm |first4=G. |date=2009 |title=Multi-phase development of a glaciated inselberg landscape |journal=[[Geomorphology (journal)|Geomorphology]] |volume=115 |issue=1 |pages=56–66 |doi= 10.1016/j.geomorph.2009.09.030}}</ref> In the northern region more known as [[Lapland (Finland)|Lapland]], highest points reach mostly from  200 m to 600 m and the landscape is a [[Fell#Förfjäll|förfjäll]] (fore-fell).<ref name="Natenterrang" /> However the most northern parts represent a more dramatic [[Scandinavian Mountains|mountain landscape]] where the [[Halti]] fell represents a highest point (1361 m) in the country.<ref name="britannicaFinland">{{cite encyclopedia |title=Finland |url=https://www.britannica.com/place/Finland |encyclopedia=[[Encyclopædia Britannica]] Online |location=Chicago |publisher=Encyclopædia Britannica, Inc |access-date=18 November 2017 |df=dmy-all }}</ref><ref>{{Cite web |last=PeakVisor |title=Finland Mountains |url=https://peakvisor.com/adm/finland.html |access-date=2024-05-20 |website=PeakVisor |language=en}}</ref>

The subdued landscape of Finland is the result of protracted erosion that has leveled down ancient mountain massifs into near-flat landforms called [[peneplain]]s.<ref name="UppslagsFiBERG" /> The last major leveling event resulted in the formation of the [[Sub-Cambrian peneplain]] in [[Neoproterozoic|Late Neoproterozoic]] time.<ref name="UppslagsFiBERG" /><ref name="japsenetal2016">{{cite journal |last1=Japsen |first1=Peter |last2=Green |first2=Paul F.|last3=Bonow |first3=Johan M.|last4=Erlström |first4=Mikael |date=2016 |title=Episodic burial and exhumation of the southern Baltic Shield: Epeirogenic uplifts during and after break-up of Pangaea |journal=[[Gondwana Research]] |volume=35 |pages=357–377 |doi= 10.1016/j.gr.2015.06.005}}</ref> While Finland has remained very close to sea-level since the formation of this last peneplain some further relief was formed by a slight uplift resulting in the [[river incision|carving of valleys]] by rivers. The slight uplift also means that at parts the uplifted peneplain can be traced as [[summit accordance]]s.<ref name="UppslagsFiBERG">{{cite web |url=http://uppslagsverket.fi/sv/sok/view-103684-BerggrundOchYtformer |title=berggrund och ytformer |last=Lindberg |first=Johan  |date=April 4, 2016 |website=[[Uppslagsverket Finland]] |access-date=November 30, 2017 |language=sv}}</ref> The [[Quaternary glaciation|Quaternary ice age]]s resulted in the erosion of weak rock and loose materials by glaciers. When the ice masses [[deglaciation|retreated]] eroded depressions turned into lakes.<ref name="UppslagsFiBERG" />{{efn-ua|Compare to southern Sweden where its large number of lakes would according to [[Alfred Gabriel Nathorst]] be indebted to the creation of basins due to the stripping of an irregular mantle of [[weathering|weathered rock]] by [[glacier erosion]].<ref name=Karnaetal1999>{{cite book |last1=Lidmar-Bergström |first1=K. |last2=Olsson |first2=S.|last3=Roaldset |first3=E.|author-link=Karna Lidmar-Bergström |date=1999 |chapter= Relief features and palaeoweathering remnants in formerly glaciated Scandinavian basement areas |title=Palaeoweathering, Palaeosurfaces and Related Continental Deposits |editor-last=Thiry |editor-first=Médard |editor-last2=Simon-Coinçon |editor-first2=Régine |publisher=Blackwell Science Ltd |pages= 275–301 |isbn=0-632-05311-9 |volume=27|series=Special publication of the International Association of Sedimentologists }}</ref>}} [[Joint (geology)|Fractures]] in Finland's bedrock were particularly affected by weathering and erosion, leaving as result trace straight sea and lake inlets.<ref name="UppslagsFiBERG" />

[[File:Uusimaa, Finland - panoramio - pan-opticon (22).jpg|thumb|The [[Kuhakoski]] rapids in [[Uusimaa]]]]
[[File:Ice-age glacial striation in Finland.jpg|thumb|200px|Effects of the last ice age: [[glacial striation]]s in a country without glaciers]]
Except a few rivers along the coasts most rivers in Finland drain at some stage into one or more lakes.<ref name=britannicaFinland/> The drainage basins drain into various directions. Much of Finland drains into the [[Gulf of Bothnia]] including the country's largest and longest rivers, [[Kokemäenjoki]] and [[Kemijoki]] respectively.<ref name=britannicaFinland/> Finland's largest lake drains by [[Vuoksi River]] into [[Lake Ladoga]] in Russia.<ref name=Natenterrang/><ref name=britannicaFinland/> Upland Finland in the east drains east across Russian [[Republic of Karelia]] into the [[White Sea]].<ref name=britannicaFinland/> In the northeast [[Lake Inari]] discharges by [[Paatsjoki]] into [[Barents Sea]] in the Arctic.<ref name=britannicaFinland/>

{| class="wikitable" align="right" style="width=70%; font-size:90%;border:1px solid darkgray;" border="1"
|+Localities in Finland by approximate date of deglaciation<ref name=Stroevenetal2016/> 
|-
| valign="top"|Year before present
| valign="top" style="text-align:center;"|Deglaciated
|-
| valign="top"|12,700
| align="right" valign="top"| [[Helsinki]], [[Kotka]]
|-
| valign="top"|11,000
| align="right" valign="top"| [[Turku]], [[Kuopio]]
|-
| valign="top"|10,900
| align="right" valign="top"| [[Jyväskylä]], [[Mariehamn]], [[Tampere]] 
|-
| valign="top"|10,800
| align="right" valign="top"| [[Lake Inari]]
|-
| valign="top"|10,700
| align="right" valign="top"| All of [[Åland]]
|-
| valign="top"|10,500
| align="right" valign="top"|[[Kajaani]]
|-
| valign="top"|10,300
| align="right" valign="top"|[[Vaasa|Vasa]], [[Oulu]]
|-
| valign="top"|10,200
| align="right" valign="top"|[[Rovaniemi]]
|-
| valign="top"|10,100
| align="right" valign="top"|[[Tornio]]
|-
|}

===Quaternary glaciation===
{{further|Weichselian glaciation|Geology of Finland}}
The [[ice sheet]] that covered Finland intermittently during the [[Quaternary]] grew out from the [[Scandinavian Mountains]].<ref name=Fredin2002>{{cite journal|author-last=Fredin|author-first=Ola|date=2002|title= Glacial inception and Quaternary mountain glaciations in Fennoscandia |journal=[[Quaternary International]]|volume= 95–96 |pages=99–112 |doi=10.1016/s1040-6182(02)00031-9}}</ref> During the last [[deglaciation]] the first parts of Finland to become ice-free, the southeastern coast, did so slightly prior to the [[Younger Dryas]] cold-spell 12,700 years [[before present]] (BP). The retreat of the ice cover occurred simultaneously from the north-east, the east and southeast. The retreat was fastest from the southeast resulting in the lower course of [[Torne (Finnish and Swedish river)|Tornio]] being the last part of Finland to be deglaciated. Finally by 10,100 years BP the ice cover had all but left Finland to concentrate in Sweden and Norway before fading away.<ref name=Stroevenetal2016>{{cite journal|author-last=Stroeven|author-first=Arjen P. |author-last2=Hättestrand|author-first2=Clas |author-last3=Kleman|author-first3=Johan|author-last4=Heyman|author-first4=Jakob |author-last5=Fabel|author-first5=Derek |author-last6=Fredin|author-first6=Ola |author-last7=Goodfellow|author-first7=Bradley W. |author-last8=Harbor|author-first8=Jonathan M. |author-last9=Jansen|author-first9=John D. |author-last10=Olsen|author-first10=Lars |author-last11=Caffee|author-first11=Marc W. |author-last12=Fink|author-first12=David |author-last13=Lundqvist|author-first13=Jan |author-last14=Rosqvist|author-first14=Gunhild C. |author-last15=Strömberg|author-first15=Bo |author-last16=Jansson|author-first16=Krister N. |author-link13=Jan Lundqvist |date=2016|title=Deglaciation of Fennoscandia|journal=Quaternary Science Reviews |volume=147|pages=91–121 |doi=10.1016/j.quascirev.2015.09.016|doi-access=free|hdl=1956/11701|hdl-access=free}}</ref>

As the ice sheet became thinner and retreated the land begun to rise by effect of [[post-glacial rebound|isostacy]]. Much of Finland was under water when the ice retreated and was gradually uplifted in a process that continues today.<ref name=UppslagsFiLandhojning/>{{efn-ua|If current rates of uplift continue Sweden and Finland will have a land boundary across the [[Gulf of Bothnia]] at [[Kvarken]] in about 2,000 years.<ref name=UppslagsFiLandhojning/>}} Albeit not all areas were drowned at the same time it is estimated at time or another about 62% has been under water.<ref>{{cite journal |last1=Tikkanen |first1=Matti |last2=Oksanen |first2=Juha |date=2002 |title=Late Weichselian and Holocene shore displacement history of the Baltic Sea in Finland |url=http://www.helsinki.fi/maantiede/geofi/fennia/demo/pages/oksanen.htm |journal=[[Fennia (journal)|Fennia]] |volume=180 |issue=1–2 |access-date=December 22, 2017 }}</ref> Depending on location in Finland the ancient shoreline reached different maximum heights. In southern Finland 150 to 160 m, in central Finland about 200 m and in eastern Finland up to 220 m.<ref name=UppslagsFiLandhojning>{{cite web |url=http://uppslagsverket.fi/sv/sok/view-103684-Landhoejning |title=landhöjning |last=Lindberg |first=Johan |date=May 2, 2011 |website=[[Uppslagsverket Finland]] |access-date=November 30, 2017 |language=sv}}</ref>