By the four cardinal points
To the south: the Ariège, the Hautes-Pyrénées and the Haute-Garonne.
On the horizon, an uninterrupted chain of snow-covered peaks, cut perpendicularly by a series of small valleys linked by high passes - a challenge largely taken up by the yellow-jacketed heroes of the Tour de France and their peloton: here are the Pyrenees. We discover them one valley after the other, from Montségur to the Gavarnie cirque. Crossed by the Garonne, the Volvestre serves as a link between upstream and downstream of the river, sometimes calm, other times more impetuous
To the west: the Gers.
A gentle landscape that we usually call "the Gascon fan": its wrinkled relief can be crossed by following the ridges or by crossing them with joy like on a fairground attraction! From the Adour valley through the Astarac, Armagnac, Ténarèze and Lomagne regions, criss-crossed by numerous rivers, its hills and valleys give it a Tuscan air.
To the east: the Tarn
The hillsides of the Lauragais region gradually give way to the more rugged terrain of the Montagne Noire, covered with forests and drained by streams that feed the Canal du Midi. Further east, the granite plateau of Sidobre, after Castres, plunges us into a mysterious universe in search of its trembling rocks and petrified silhouettes. Further north, the fertile valleys of the Tarn and the Vère contrast with the formerly more arid Ségala.
In the north: the Tarn-et-Garonne
The Garonne valley marks a break with the rest of the Midi-toulousain region, isolating Tarn-et-Garonne (the latest administrative division in 1808) from the other departments, opening the road to the Quercy Blanc and the Grands Causses. Its very diversified soils create the unity between these regions. Fertile clay and silt in the south, limestone and cut stone in the north. Its temperate climate has made it the orchard of the region.
Nature in its raw state!
Causses and segalas
The Causses of Quercy - Causses of Limogne and Caylus in Tarn-et-Garonne - are highly eroded karstic plateaus characteristic of the south and west of the Massif Central. The inhabitants are called caussenards; this word comes from the Occitan cauce from the Latin calx meaning lime. In the karst, the surface water disappears underground. In the rock which is outcropping in some places, they come out in resurgences called "lavognes" serving as watering places for the herds. Elsewhere, sinkholes are formed - as a result of rock collapses or their dissolution -, chasms or dried out valleys called "combes". These areas are suitable for pastoralism and the cultivation of wheat, barley, alfalfa or rape
The ségalas are located on the eastern margins of the region, between 500 and 1,200 m in altitude. These plateaus with a harsh climate and cold soils have long been a land of rye (hence their name) and a land of emigration, especially around the coal basin of Carmaux and Blaye-les-Mines which saw many Poles, Italians and Spaniards settle in the region. These lands are crossed by deep gorges, Aveyron, Cérou or Viaur, which do not lack energy assets - hydroelectricity - and tourism.
Molasse, Terreforts and Boulbènes
The molasse is a soft rock rich in clay, resulting from the erosion of the Pyrenees, which sometimes presents more resistant calcareous strata. These lands that fill the Garonne river channel are sculpted by hills with very fertile but heavy soils that are difficult to work, the terreforts. They are mainly found in Gascony and in the Lauragais region. The terraces of the large alluvial valleys have boulbènes, often stony, poorer in nutritive elements, they harden in summer and crack. This is a prized soil for ceramics.
Greenhouses and rivers
In the Gascon landscape, each valley is composed of three "sets" that the peasant himself had differentiated and named because of their physical and morphological characteristics. At the bottom of the valley, the Ribère defines the "alluvial plain of a river". The valley is covered with crops and orchards while the Serre - the top of the hills and their steep slopes - long and crowned with clay-roofed villages, separates large valleys. On the gentle slope, the Boubée is tiered with rows of vines
Cirques and gaves
As for the Bigorre, it is crossed by many small rivers: the gaves (pronounced "gabé" which means "deep river"). The Gave de Pau (also called Grand Gave towards Saint-Pé-de-Bigorre) collects almost all of them; it is the main tributary of the Adour. On the mountain side, no arena but cirques! Formed in the quaternary period, these natural amphitheaters, monumental, with a vertiginous verticality, were dug by ancient glaciers. The one of Gavarnie (Hautes-Pyrénées) is one of the most famous, with a diameter of 6 km; in Ariège: the circuses of Campuls, Anglade and Cagateille are particularly frequented for their ibexes.
A rock giant
The clash of the Titans. The Pyrenees are the result of the struggle between two continental blocks: the Hispanic one in the south and the European continent in the north. Separated a hundred million years ago, they collided 45 million years ago, compressing and crushing a quantity of materials and creating a vigorous summit ridge (between 2,500 and 3,404 m in altitude at the Aneto peak in Spain, 3,298 m at the Vignemale in France) above a piedmont preceded by hills that soften this relief, closing the horizon from east to west over a distance of about 400 kilometers. Some summits give a real identity to the chain: Pic du Midi or Pic d'Ossau, they are easily recognizable. On the other hand, the rivers open up numerous narrow valleys perpendicular to the summit, the cluses
These landlocked territories have a strong identity: Pays de Foix, Couserans, Comminges, Bigorre, Pays Toy. Numerous "ports" allow their crossing to Spain. The French side, shorter and steeper, is provided with high altitude lakes and many sites are favorable for electricity production. From the end of the Second World War to the beginning of the 1970s, about 300 power plants were put into service. The "Route des Cols" allows you to enjoy the most beautiful panoramas. Thirty-four passes (of which 16 are in the Midi-toulousain region): among the most famous are the Aubisque (1,709 m), the Tourmalet (2,115 m) and the Aspin (1,489 m). Created in the 19th century under the impulse of Emperor Napoleon III and his wife Eugenie, this road used to link the various thermal spas
The Montagne Noire owes its name to its very dense forest cover. This cool and humid middle mountain culminates at 1 210 meters at the Pic de Nore (Aude). Geologically, it is attached to the Massif Central, of which it marks the extreme southern tip with the town of Mazamet at its feet. Stretching over 80 km long and 60 km wide, it is a paradise for hiking.
Water, water and more water!
The hydrographic network is particularly dense: lakes, rivers, gorges, gaves, canyons, waterfalls... Two rivers mark the southern and northern limits of the Midi-toulousain: the Adour and the Garonne. Originating in the Aran Valley, the Garonne constitutes the major axis. The Pyrenean torrent expands with the reception of the waters of the Ariège and the Tarn, its flow more than doubles. Other tributaries come to enlarge its bed: Gers, Baïse, Save. The Garonne corridor then reaches a width of about twenty kilometers in its middle valley, between Toulouse and Agen. On its course, many ramiers constitute naturally floodable zones, with abundant and wooded vegetation.
The Adour crosses the Aquitaine Basin from its source in the Campan valley in Bigorre, where it is born from the union of three torrents, crosses the city of Tarbes, bypasses the Madiran vineyards, irrigates the cantons of Rivière-Basse and Vic-Bilh without ceasing to widen until its mouth after Bayonne. If its mildness seduces fishing enthusiasts (it remains one of the rare rivers in Europe to still have salmon spawning grounds), navigation is no longer possible in this part of its course.
But the valleys of the Tarn and the Ariège are also of great importance. Modest rivers such as the Lèze flow at the bottom of somewhat disproportionate corridors! Some are open to navigation like the Baïse. More discreet, hidden in the subsoil, the water circulates in chasms (Esparros known for its aragonites) and caves in the form of underground river (Labouiche, Bétharam). It releases its CO2 and deposits a part of its dissolved carbonate in beautiful concretions: stalagmites and stalactites. Beware: these waterways are very capricious. Nourished by the concomitance of the snow melt with abundant precipitations, they overflow violently at least once a century: we speak then of centennial flood. The inhabitants of Toulouse remember the one of June 23, 1875, on that day the flow approached 8000 m3/second! In March 1930, the Montalbanais measured more than 11 meters of water at the Old Bridge! More recently, the years 2020 and 2021 were marked by consequent floods although the courses were dyked in certain cities like Toulouse.
