Its reputation precedes it, and most who trek the route describe it afterwards as one of the toughest they have ever completed. Others find they are unable to complete it, having seriously underestimated its nature. The GR20 climbs high into the mountains and stays there for days on end, leading ordinary trekkers deep into the sort of terrain usually visited only by mountaineers. The scenery is awe-inspiring, with bare rock and sheer cliffs in some parts, contrasting with forests, lakes and alpine pastures in other places. Those who walk the route are only too eager to share their experiences with those who haven’t, so that everyone who completes the GR20 is probably responsible for two or three more people trekking it. It has been estimated that as many as 30,000 people trek the route each year!
Most people would relish the opportunity to trek through wild mountains, feeling the roughness of the rocks with their fingers, enjoying the clarity of the views under a blazing Mediterranean sun, maybe enlivened with streaks of snow on the higher slopes. There is the perfumed scent of the maquis, and the chance to spot eagles in flight. You can do all this, provided you keep an eye on the weather, since Corsica is noted for severe summer thunderstorms, while in winter the mountains are truly alpine. There is the prospect of sleeping in rustic refuges, or even better, sleeping under canvas, peeping out to discover the mountains bathed in moonlight. On moonless nights, you can gaze awe-struck at the firmament speckled with millions of pinprick stars. You can enjoy all this and more provided you make careful plans and walk within your limits.
The GR20 is an experience, more than simply a trek, and those who try and rush the route may find they finish with certain regrets. While the ‘classic’ route can be covered in a fortnight, discerning trekkers will be happy to include variations – maybe climbing some of the nearby mountains, or visiting nearby villages. The main route allows little opportunity to meet ordinary Corsicans, but a detour into a village, or better still, a night or two spent with a Corsican family, will enhance the quality of the trek. Take the time to sample local foodstuffs, including the meat and cheese produced in the mountains, maybe washed down with a homemade wine, but always be aware of where your next fill up of water is available. Corsican food is generally simple and wholesome – ideal for a trek through the mountains, and all part of the joy of travel!
Geology
Corsica is often referred to as ‘the Granite Isle’, and it is easy to dismiss the whole island simply as one enormous granite massif, but this would be wrong. Corsica is geologically divided into two parts by a line running very roughly from Île Rousse on the north coast, through Corte in the middle of the island, to Favone on the east coast.
Everything west of this line is referred to as ‘Hercynian Corsica’, named after a mountain-building era that occurred between 345 and 225 million years ago. The bedrock in this, the greater part of Corsica, is essentially a massive granite intrusion. It was pushed into the Earth’s crust under immense pressure and temperature, so that the rock was in a molten state. As it cooled over a long period of time, coarse crystals formed, chiefly of quartz, feldspar and mica. Geologists sub-divide the granite according to its mineral composition, which varies from place to place, especially around the northwest of the island. Granophyres and quartz porphyries are common, and conspicuous linear dykes have been intruded into some rocks. The mountains that were raised during the Hercynian era are long gone, and the granite mountains of Corsica are merely their deepest roots.
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.
Brief history
Those who trek the GR20 may feel that they are completely bypassing anything of historical interest on Corsica. Transhumance, the seasonal movement of livestock to summer pastures in the mountains, followed by a retreat to the low ground before the onset of winter, has been practised in Corsica for thousands of years. The island has been invaded dozens of times by all kinds of armies, and native Corsicans have often fought to resist each successive attempt at colonisation. However, high in the mountains, there are few ancient monuments or proud fortifications, nor are there any museums to visit. The GR20 is essentially a tough mountain trek almost completely divorced from the history and culture of the island. History, by and large, was wrought elsewhere on the island, and the best you can do is at least be aware of some of the key events and turbulent times that Corsica has experienced.
| 7000 BC | The first human settlers probably reached Corsica from Tuscany during the Palaeolithic era. They were hunter/gatherers who lived in caves and other natural shelters, using only basic stone tools and items of pottery. |
| 6600 BC | ‘Bonifacio Woman’, a Neolithic woman whose skeleton was discovered near Bonifacio, is the earliest human being discovered on Corsica. Soon afterwards, people began the tradition of transhumance, involving the seasonal movement of animals to summer pastures in the mountains, retreating to the coast and lower valleys in the winter. As semi-nomads, shepherds and herdsmen built themselves temporary shelters. |
| 4000 BC | The climax of the Megalithic era, during which huge stone monuments, menhirs and dolmens, were raised around the island. Human society was clearly well organised to enable people to build such structures, and the period of construction spanned several centuries. |
| 1500 BC | Invaders known as the Toréens, named after the stone towers they erected, landed at Porto Vecchio and gradually spread through Corsica. The earlier inhabitants, however, continued to raise their own stone monuments even into the Iron Age. |
| 565 BC | Greek refugees from Phocaea established a colony at Alalia, where Aléria now stands. They were traders who planted olives and vines, but were troubled by attacking Carthaginians and Etruscans. |
| 535 BC | The Greeks abandoned their colony, and the Etruscans who occupied the site were later displaced by the Carthaginians. |
| 259 BC | Roman soldiers were sent to Corsica to prevent the Carthaginians advancing through the Mediterranean. Native Corsicans joined forces with the Carthaginians to hold the Romans at bay, so the Roman conquest took 40 years to subdue the island. Roman power remained dominant for over 500 years, and while ports were constructed, little change took place in the interior. The Roman strategy was essentially to prevent any other power from occupying the island, which was conveniently close to Rome. |
| 303 AD | Christianity had been brought to Corsica, and the beheading of Santa Restituda gave the island its first Christian martyr. As the Roman empire began to wane, Vandals began to raid coastal settlements and were well established on the island in the middle of the 5th century. |
| 534 AD | Byzantine forces launched an invasion of Corsica and made it part of their empire. However, they in turn suffered a series of raids, notably from the Ostrogoths, and later from the Lombards. |
| 725 AD | The Lombards took control of Corsica, but by this time the Saracens were sending raiding parties to the island, harrying coastal settlements. |
| 754 AD | Pépin le Bref, King of the Franks, offered to give Corsica to the Pope after freeing it from Lombard control. The process took 20 years, and it was Pépin’s son, Charlemagne, who finally handed the island to the Pope. However, the Saracens continued raiding the island and at times almost completely overran it. |
| 825 AD | Ugo della Colonna is reputed to have driven the Saracens
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