Plateaux and massifs
In Lozère more than anywhere else, the land and the people have been influenced by the nature of the subsoil. Basalt, granite, limestone, schist: this tetralogy alone explains the imposing and sometimes mysterious character of the Lozère landscape.
To the north-west, Aubrac is a thick pile of basaltic nappes covering the crystalline basement, a continuation of the great Auvergne volcanic complexes. The landscape is marked by distinctive shapes, such as the basalt peaks and walls at Roc de Peyre and La Fare de Chirac, and the prismatic expanses at Pont des Nègres... Chiseled by the glaciations of the Quaternary, which left glistening lakes and greyish peat bogs, and enlivened by the murmur of streams, it stretches peacefully, covered with moorland and meadows. Its highest point is Signal de Malhebiau at 1,471 m, the highest point in Lozère. To the northeast, the crystalline bedrock of the Margeride is one of the largest granite massifs in Europe. These high plateaus, covered with pastures but with remnants of Scots pine and beech forests, exceed 1,000 m on average, but are cut by deep, rounded valleys. In the center, the landscape is a hodgepodge of harmonious ridges. The 1,565 m-high Signal de Randon towers just above the rest. The decomposition of the granite has left large boulders that dot the moors or sometimes pile up in rocky chaos. To the south of the Margeride is the Goulet mountain, a schist massif resting on the crystalline basement. It isolates a very unusual little region in these parts: the plaine de Montbel, a small highland causse that makes you wonder how it ended up there. Often, in Margeride, the soil is poor, the climate harsh and rye is the only cereal that men have been able to grow in these austere lands. Broom heath dominates, covered in spring by an infinite number of dazzling yellow patches. Over 300,000 sheep used to spend their summer vacations here.
Gorges and forests
The Cévennes to the south-east are the domain of schist. The headwaters of the Tarn divide them into two major massifs, with granite bedrock outcrops at the summit: Mont Lozère (1,699 m at Finiels) and Mont Aigoual (1,565 m) at the department's southernmost point. In the center, the Bougès mountain is a transition zone between the northern Cévennes, dominated by moorland, and the forested southern Cévennes. On either side, the "serres" mark the landscape with their knife-sharp schist ridges, separated by deep valleys with steep, rugged slopes and thick forests of conifers, beech and chestnut. The three most important are the Vallée Longue, the Vallée Française and the Vallée Borgne, each with its own river. For centuries, this region was the richest in Lozère. As space was limited, men built terraces, raised the soil and created a network of irrigation canals (béals). They planted vines, fruit trees, vegetables and, above all, the "tree of life", the chestnut. The Cévennes landscape retains the traces of this intense humanization, despite the depopulation that has affected it over the last century.
To the south-west, everything changes. During the Secondary Era, the sea advanced over the ancient massif and, for 60 million years, limestone and marl were deposited in alternating layers thousands of meters high. This was the time of the dinosaurs, and you can still see traces of some of these animals near Florac, at Saint-Laurent-de-Trêves. Rivers, which flowed at greater rates than today, cut imposing gorges, sometimes over 500 metres deep, separating the now barren and arid plateaus known as the causses. Human activity is concentrated in a few hamlets or isolated farms, always located near small clay-bottomed depressions, the only places where crops can be grown. The causses may seem arid, but even though it rains on average twice as much as in Paris, there's plenty of water below the surface.
So much water!
Water trickles down, penetrating the ground through cracks in the rock, dissolving the limestone and transporting it to the depths, where it is deposited in the form of calcite gems in underground cavities. Two of these, explored at the end of the last century, have now been developed and are one of the highlights of Lozère tourism: aven Armand, on the Causse Méjean, and grotte de Dargilan on the Causse Noir. Sometimes on the surface, in the dolomite (a rock close to limestone) massifs, strange shapes emerge: animals, pillars, monumental arches, as at Montpellier-le-Vieux, Nîmes-le-Vieux or Les Arcs-de-Saint-Pierre.
With its thousands of springs and streams winding through the meadows, Lozère is in a way France's water tower; and it proves it by supplying three basins: that of the Loire via the Allier, that of the Rhône via the Luech and the Gardons, and that of the Garonne via the Truyère, the Lot and the Tarn. Let's bet there are a few brooklets on the Aigoual that flow directly towards the Hérault and the Mediterranean. But we can't talk about Lozère's rivers without mentioning the Tarn and its famous gorges, which are entirely Lozère, despite those who, a few years ago in the neighbouring region, wanted to make them their own... From Ispagnac to Le Rozier, over a distance of 50 km, they are one of France's natural wonders. The average depth varies from 400 to 500 m, and at the cirque des Baumes the distance between the causses is reduced to 1,000 m. Thanks to their sinuous course and the variety of their walls, sometimes rocky, sometimes covered with vegetation, their appearance is constantly changing, alternating dark corridors and amphitheaters that shine with a thousand lights.
