On the edge of a Massive Massif


Gorges d’Héric (photo taken by your contributor)

I have lived in south-west France for 8 years, while completing several British university degrees, mostly around earth sciences and environmental studies – hence my semi-professional and unreservedly enthusiastic geological interest.

Castres is famously ‘rugby country’ (at least amongst us aficionados); otherwise, these last ramparts of the Massif Central are little known, even by the French. The nearest part of the Massif to the Pyrenees, a proverbial ‘well-kept secret’, this special and surprisingly diverse area has huge potential for enthusiastic geologists and travellers alike.

This wonderfully detailed (therefore slow-loading) NASA relief map of France shows that the Massif Central stretches all the way from the Alps to the Pyrenees. The Montagnes Noires (Black Mountains), are right at the south-west, where the Aquitaine Basin starts sloping gently towards the ocean; they form an east-west sub-range, with the slightly higher but more amorphous Hauts (uplands) of Lacaune just north. Geologically, all belong to the Massif.

Figure 1: The Black Mountains, the Lacaune Hills and the Sidobre [Source: Adapted from http://photojournal.jpl.nasa.gov/jpeg/PIA03393.jpg]

Figure 1: The Black Mountains, the Lacaune Uplands and the Sidobre [ Source: Adapted from http://photojournal.jpl.nasa.gov/jpeg/PIA03393.jpg ]

“South-west France” suggests typically Mediterranean vegetation: scrub, gorse, cacti. This is somewhat valid for the southern slopes of the Black Mountains, between Carcassonne, the UNESCO-listed medieval city (the fortress of which was used by Kevin Costner as his Robin Hood ‘Nottingham Castle’!) and Béziers – also with their ‘Cathar Castles’ (a useful label, albeit a misnomer – see below). Here too are the southern slopes’ reputed ‘Languedoc’ wines such as Corbières, Minervois, and Saint-Chinian – geological fieldwork and leisure are not mutually exclusive pursuits!

Carcassone all

Figure 2 Various views of Carcassonne’s defensive walls, the ‘cité’, and the fortified castle; taken by your contributor

To the north, in sharp contrast, a rain-shadow fosters vast natural mixed coniferous-deciduous forests, important if little-known rivers such as the Tarn, the Aveyron…. and thus some fantastic gorges (and a few grottos, such as Cabrespine and Devèze). For over three centuries, this rainfall has been artificially feeding the 17th century Canal du Midi, also UNESCO-listed, which is situated to the south of the mountains; the canal stretches from the Mediterranean at Béziers/Agde westwards as far as Toulouse. (The 1850s Garonne Canal links Toulouse to the Atlantic Ocean, the two canals forming the ‘Canal of the Two Seas’).

The above-mentioned Tarn river formed (and is still forming) the Tarn Gorges, over which the famous and fantastic Millau Viaduct crosses; this is officially the world’s tallest bridge. Not far downstream is beautiful Albi – which is, with my apologies for repetition, also UNESCO-listed! Further west are the Gorges d’Aveyron which offer beautiful villages and family-friendly canoeing – the gorges up-close-and-personal.


Figure 3 Millau Viaduct, Millau and its bridge (Source: used with the permission of the rights holder, Eiffage)

Space here does not permit me to do justice to the variety and quality of the local geology. But please indulge me one close-to-home example, the Gorges d’Héric (map here), and even then only briefly, alas. Access is easy, there are pleasant walks for all ages, with rock climbing for the more adventurous. Further, visitors can bathe in fresh spring waters.

These gorges are bordered on one side by the Massif du Carroux (gneiss, steep, rugged slopes) and on the other by the Monts d’Espinouse (more complex: granite, gneiss and schist, with seams of soft bituminous coal; it is here where the Agout River rises). The national park is noted for its wild ‘mouflon’ sheep roaming the steep escarpments here. Botany fans too will be spoilt.


Figure 4 Gorges d’Héric, various and varied images, taken by your contributor; they are representative regarding the site’s accessibility, but do not do it justice regarding the views – and you cannot hear the waterfalls from the photos!

The Agout later flows through Brassac, where I work at Transports Maury. Of both personal and professional interest, therefore, not least because it is literally outside my office door, is the Sidobre, a major granite site, important both for its beauty and for its extractive value. In the interest of aesthetics, these two activities are wisely kept apart, though of course many visitors, not least geology enthusiasts, come to study the mining too. Many appreciate the associated artwork using the granite. The Champs Elysées ‘Parisian walkways’ are paved with Sidobre granite.


Figure 5 Transports Maury’s ‘home’: Brassac, with the 12th century asymmetric cobblestone bridge in the foreground (and shown right), made of course from local granite. Source: http://www.tourisme-tarn.com.

There are many geological attractions within traveling distance of ‘home’. Just south of the Sidobre, up the road from Castres (the aforementioned rugby town on the Agout River), is Le Causse de Caucalière, which is a “vast lacustrine plateau (about 1900 hectares §) of limestone dating from the Tertiary Period, rich in fossils” — my translation of the website of one of the municipalities situated on the plateau. (§ ~4700 acres).

Little Venice

Figure 6 The “Houses on the Agout River” in Castres, called by some “Little Venice”. Source: http://www.tourisme-castres.fr/

Slightly further afield, surely meriting a multi-day trip, are the Pyrenees, with their wonderfully asymmetric and unusual orogeny due to the “opening of the Bay of Biscay”, thus ‘wedging’ (both ‘pro-wedging’ and ‘retro-wedging’, for enthusiasts of the details) and rotating the future Iberian peninsula west-to-east into south-west Eurasia (i.e. France).

The Pyrenees are clearly visible from local uplands, and are easily accessible by minibus or coach. On the way, explore the ‘Cathar Castles’ (ask your guide ‘en route’ why this is the aforementioned misnomer) and Bugarach, more interesting for its beauty and its reportedly upside-down (actually a thrust fault) geology than for the fact that it was the village at the end of the world – back in 2012!

Composite satellite image of the Pyrenees (NASA)

Composite satellite image of the Pyrenees (NASA)

In the opposite direction, I suggest a very different multi-day excursion, to visit the Auvergne (extinct) volcanos and the (yet again, UNESCO-listed) Causses and Cevennes agro-pastoral landscape. All this without even starting to present my adopted region’s culture, history, prehistoric grottos, gastronomic and oenological attractions!

I recognise that I am lucky to live here, and further to work in tourism, not least promoting local geological attractions – having earth-science, environment and natural science qualifications from a British university. I want to share this, so I am more than enthusiastic to advise geology enthusiasts (and others) on fieldwork and leisure trips. Indeed, and as already discussed, fieldwork and leisure are not mutually exclusive, and never will be. Thankfully.

  • Peter Culleton has various qualifications, including in geology; he works at Transports Maury, a transport and tourism company based in the Midi-Pyrénées region of France.