Читать книгу The GR20 Corsica. The High Level Route онлайн

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Everything east of the dividing line is referred to as ‘Alpine Corsica’, simply because the rock types were pushed up during the later era of mountain building that was associated with the creation of the Alps. There are several rock types, including schists of uncertain age that have been folded and metamorphosed time and again. There are also layers of limestone and sedimentary rocks that were formed on the seabed, before buckling under immense pressure to form mountains. Fossils contained in these rocks reveal that they were formed in the Upper Carboniferous, Liassic and Eocene periods – with respective ages from around 300, 150 and 50 million years ago.

The Ice Age, which ended only around 10,000 years ago, had a profound effect on the mountains of Corsica. The mountains were high enough to ensure that snow never melted from year to year, but increased in depth so that glaciers could form, grinding out deep corries and carving steep-sided valleys into the mountainsides. During a much wetter period than at present, powerful rivers scoured the valleys deeper, and spread fans of alluvial rubble further downstream, and around the coast. During harsh winters in the mountains, conditions are again reminiscent of the Ice Age, when the high corrie lakes freeze completely and deep snowdrifts are heaped up against the cliffs. By the time Man discovered Corsica, the island valleys were well wooded, although parts of the coast and the high mountains were bare rock, much as they are today.