Costa Alta e Arquipélago de Kvarken, Suécia e Finlândia

O Arquipélago de Kvarken (Finlandia) e a Costa Alta (Suécia) situam-se no Golfo de Botnia, prolongamento do Mar Báltico para norte.

As suas 5.600 ilhas e ilhéus do Arquipélago de Kvarken singularizam-se pelas curiosas morenas de picos ondulados, as morenas de Geer formadas pelo derretimento da camada de gelo continental ocorrido nos últimos 10.000 a 24.000 anos.

Neste arquipélago emergem continuamente novas ilhas devido a uma elevação glácio-isostática rápida, fenómeno que ocorre quando os terrenos comprimidos pelo peso de um glaciar se elevam quando este se derrete. O índice de elevação do arquipélago é um dos mais elevados do mundo.

Como consequência do avanço das terras do litoral, as ilhas surgem das águas y unem-se, a superfície das penínsulas aumenta e as baías acabam formando lagos, que despois se  convertem em pântanos e  turfas pantanosas.

A Costa Alta também se configurou em grande medida pela conjunção da glaciação, do recuo dos glaciares  e pela emergência de novas terras.

Desde o recuo final dos glaciares da Costa Alta há 9.600 anos, a elevação da ordem dos 285 metros, constitui o maior  “ressalto” jamais observado.

A Costa Alta constitui um sítio excepcional para a compreensão dos processos geológicos que que conduziram à  formação dos glaciares e das zonas de elevação da  superfície da Terra.

FR:

L’archipel de Kvarken (Finlande) et la Haute côte (Suède) sont situés dans le golfe de Botnie, qui prolonge la mer Baltique vers le nord. Les 5 600 îles et îlots se singularisent principalement par les curieuses moraines à crête bosselées, ou moraines de Geer, formées par la fonte de la nappe de glace continentale composées il y a entre 10 000 et 24 000 ans. L’archipel de Kvarken s’élève de manière continue du niveau de la mer du fait d’un relèvement glacio-isostatique rapide, lorsqu’une terre précédemment comprimée par le poids d’un glacier se relève après la disparition de ce dernier, fait de ce taux de relèvement dans la région l’un des plus élevés au monde.

Du fait de l’avancée du littoral, des îles apparaissent et s’unissent, des péninsules grandissent, des lacs se forment depuis les baies et deviennent des marais et des fagnes tourbeuses. La Haute côte a aussi été largement façonnée par l’association de processus de glaciation, de recul des glaciers et d''émergence de nouvelles terres. Depuis le retrait final des glaces de la Haute côte, il y a 9 600 ans, le relèvement est de l''ordre de 285 m, ce qui correspond au « rebond » manifeste le plus important jamais observé. La Haute côte est un site exceptionnel pour la compréhension des processus importants qui ont formé les glaciers et les zones de relèvement de la surface de la Terre.

EN:

The Kvarken Archipelago (Finland) and the High Coast (Sweden) are situated in the Gulf of Bothnia, a northern extension of the Baltic Sea. The 5,600 islands of the Kvarken Archipelago feature unusual ridged washboard moraines, ‘De Geer moraines’, formed by the melting of the continental ice sheet, 10,000 to 24,000 years ago. The Archipelago is continuously rising from the sea in a process of rapid glacio-isostatic uplift, whereby the land, previously weighed down under the weight of a glacier, lifts at rates that are among the highest in the world. As a consequence islands appear and unite, peninsulas expand, and lakes evolve from bays and develop into marshes and peat fens. The High Coast has also been largely shaped by the combined processes of glaciation, glacial retreat and the emergence of new land from the sea. Since the last retreat of the ice from the High Coast 9,600 years ago, the uplift has been in the order of 285 m which is the highest known ''rebound''. The site affords outstanding opportunities for the understanding of the important processes that formed the glaciated and land uplift areas of the Earth''s surface.

Outstanding Universal Value

Criterion (viii): The High Coast/Kvarken Archipelago is of exceptional geological value for two main reasons. First, both areas have some of the highest rates of isostatic uplift in the world, meaning that the land still continues to rise in elevation following the retreat of the last inland ice sheet, with around 290 m of land uplift recorded over the past 10,500 years. The uplift is ongoing and is associated with major changes in the water bodies in post-glacial times. This phenomenon was first recognized and studied here, making the property a key area for understanding the processes of crustal response to the melting of the continental ice sheet. Second, the Kvarken Archipelago, with its 5,600 islands and surrounding sea, possesses a distinctive array of glacial depositional formations, such as De Geer moraines, which add to the variety of glacial land- and seascape features in the region. It is a global, exceptional and diverse area for studying moraine archipelagos. The High Coast and the Kvarken Archipelago represent complementary examples of post-glacial uplifting landscapes.

souce: UNESCO site

UNESCO site:   http://whc.unesco.org/en/list/898  » texts in Arabic, Chinese, Russian, Spanish and  Japanese