Natural treasures

The transverse rift valley (clue) of Sisteron and the rock of La Baume

It is often said that Sisteron is a gateway to Provence, the Rock of Baume and its transverse rift valley are its most representative image. At the same time a topographic and climatic gate, this sculpture composed of vertical limestone strata, and folds known all over the world, is considered by geologists as a real curiosity. The limestone sediments deposited at the bottom of the sea at the end of the Jurassic formed layers that folded once at the end of the secondary era during the establishment of the large folding that form the Mont Ventoux, Lure... then a second time during the uplift of the Alps during the tertiary. The work of erosion did the rest, offering us "a great bare rock carved like a cathedral" as Paul Arène wrote!

The Riou gorges

During a refreshing hike in the shade, you will discover the beautiful gorges of Riou and their amazing geology! These rocks made of marl and limestones are wrinkled, folded, deformed, to finally form a V: this is a upward syncline. It is rare to see such a beautiful one in France. The path runs along large sections of black marl, crosses a black pines forest, a small stone bridge and a slight ascent leads you on a plateau from which you can admire a superb view of the whole gorge. Nature lovers will be delighted by these gorges and pools of water, as well as by the local fauna and flora.


I discover with images


Monges Lake or Esparron Lake

There is a 300 m difference in altitude for reaching the lake of Monges (altitude: 1544m) from the village of Esparron-la-Bâtie, former municipality now belonging to Bayons. This artificial lake, created in 1970, is surrounded by a forest of larches and subalpine pines reflected in the water. After having walked on this portion of the GR6, the site, a true haven of peace, invites you to a break under the refreshing shade of the larches.


You will discover unusual natural forms, such as "La Mole castle" and "champignon" (the mushroom): Tectonic movements that followed the alpine sea retreat between - 65 and - 4 million years have created gorges, waterfalls, powerful bars like the mountain "Jouère" whose summit "La Croix de Saint Jean" culminates at 1886 m. Later, erosion sculpted some remarkable forms such as "The Castle of the Mole" on the path of Jouère or the "Champignon" on the track leading from Valavoire to Authon


Gypsum is part of the local heritage; a natural material it is used since the Middle Ages in the surrounding buildings that still bear witness today (ancient walls, plasterwork, dovecote at Upaix...). A quarry of gypsum is exploited on the municipality of Lazer, to turn this rock into plaster. The hill of the plasterer with whitish summits is well visible from the neighborhoods (look out: the access to the site is dangerous and forbidden); it sheltered an old medieval village whose history dates back to the 11th century and ends during the 14th century. Excavation campaigns have been carried out and the research has uncovered remnants of gypsum dwellings and daily life equipment: bread ovens, cisterns for collecting rainwater, silos for storing cereals and many items now preserved at the Regional Archaeological Depot in Aix-en-Provence. A sculpture symposium on gypsum and plaster is held in Laragne every 2 years.

Focus on...

There is a Retrouvance® refuge, (registered trademark of the National Forest Office), near the Lake des Monges, out of sight. 2 possibilities are offered to enthusiast ecotourists: lodge rentals and Retrouvance® hiking circuits; guiding, accommodation, catering and luggage transport included.


The dino eggs of Rosans

In the Rosans area, a real geological curiosity to discover: the "dinosaur eggs". They are actually sandstone balls, embedded in a vast sandstone bench that was formed 110 million years ago during the secondary era. A circuit goes around this lunar plateau, on sandy ground, among thyme and heather. Access by la Beaume, 2km from St-André de Rosans. Please respect this site which is private, and do not collect anything on the spot, so that the next visitors can also enjoy it. Some of these balls are two meters in diameter!

The valley of Oule

This very picturesque valley of Val d’Oule offers a wide variety of landscapes, a shaded gradient from the green meadows of Sainte-Marie to the peaks jagged by erosion, and where walnut trees and lime trees are part of the local heritage. It is not uncommon to admire the majestic flight of raptors around Montmorin: golden eagles, short-toed eagle, griffon vultures... On the banks of the Oule torrent, when you are discreet, you may see the beaver colonies and their incessant work around the village of Bruis.

The marls

You will often notice black soils in the landscapes, very frequent in the Baronnies, the marls spread their black patches along the steep slopes. Their extravagant form, called "elephant back", was sculpted by runoff. Black soils are the most frequent, but the valley of Rosans or that of l’Epine , show the traveler "blue marl", dating from the Cretaceous (-100 million years). These formations, devoid of vegetation, sometimes contain fossils. Marls are quite common in Sisteron Büech! With color that varies from sand to charcoal according to humidity and brightness, these soft rocks carved by erosion sometimes give the landscapes a Wild West look!

Did you know ?

The white horse of Bruis. This local curiosity, completely integrated into the visual heritage for several generations is simply the work of Mother Nature who, on the Devès Hill facing the village, used what was available: trees and white gravel to draw this horse, tirelessly riding to the Upper Valley of Oule since almost one century as far as the seniors remember, and maybe even more!

Sisteron Buëch

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