The Bès Valley is an exceptional place that reveals part of the history of the Alpine chain and that of distant forgotten landscapes. The rocks and fossils bear witness to lands, life forms and environments from the past.
The Bès cuts its river bed in preserved geological massifs, which can be seen as the archives of the past. For the wanderer discovering the valley, it is an opportunity to travel back in time. From marshy environments 300 million years old to current torrential deposits, astonishing landscapes continue to follow one another along the river: hypersaline lagoons, deep sea, beach or arid plains. The landscape of the valley offers striking contrasts of shapes and colours that question visitors as to the origins of this extraordinary natural architecture. Just over a short distance, the landscapes present a multitude of interests that researchers and academics from “France and Navarre” know well. Since the end of the 1950s, the valley has been the playground of choice for universities, which regularly organise courses here to introduce students to geology.
This great geo-diversity results from a long sedimentary and tectonic history. The “visible” sedimentary history begins 300 million years ago and continues until today, showing periods of contrasting activities linked to the formation of relief in connection with the movements of the Earth’s crust. Sediments (old mud, sand, gravel or coarser materials) have become rocks. Deposited one above the other, they form successive layers. The uppermost layers contain information (fossils, sedimentary deposits) that make it possible to reconstruct former landscapes of the area. The folds that can be seen everywhere in the valley (in particular those of the alpine uplift) testify to the deformation of the original sedimentary stack. In addition, erosion has cut into the rocks revealing geological layers that are normally deeply buried. Thus, each layer reads like a page from the archives, from which a few lines or words are sometimes missing.
Source: Myette Guiomar, Doctor of Geology, Scientific Officer, Haute Provence Natural Geological Reserve
The Ammonite Wall
At the exit of Digne, in the direction of gîte or bed and breakfast, cross the “Eiffel” bridge spanning the Bléone, go past the entrance to the Promenade Museum (interpretation centre of the Haute-Provence UNESCO Geopark) and continue on the road until you reach the Ammonite Wall. It is a world famous site, which has become emblematic of geological heritage. This inclined slab of 320m2 holds more than 1550 large ammonites (70cm) as well as some nautiluses (cephalopod molluscs with external shells related to squids). You will see live nautiluses in the aquariums of the Promenade Museum. Ammonites, on the other hand, disappeared 66 million years ago. Past this site, you will enter the Bès Valley with its unique landscapes and geology.
The Robine Ichthyosaur
This is a fossil of a marine reptile dating back 185 million years, visible near the Col du Jas (commune of La Robine sur Galabre). The fossil rests in a site laid out for the public with numerous interpretation panels. The ichthyosaur is relatively complete (skull, rib cage, vertebrae and fins). It belongs to the “boreal” genus, which is very rare. Its presence here has led to paléogéographic reconstructions. From these, it is deduced that a connection exists between the Boreal Ocean (at Germany’s location at that time) and the Tethys. Ichthyosaurs lived in the seas of the Mesozoic era. Predatory carnivores, they hunted and fed mainly on belemnites and even ammonites. The last ichthyosaurs disappeared de before the end of the Mesozoic era, around 90 million years ago.
La Robine sur Galabre and its famous black lands
The black lands, also called “robines” locally, is a landscape of marly hillocks interspersed with narrow passages in between through which erosion has cut into this friable substance. The effect is a lunar-like landscape, which both children and mountain bike enthusiasts adore. The marl is composed of limestone (20% to 40%) and clay (60% to 80%). Its black colour is attributed to the presence of organic fossil matter as well as micro-grain iron sulphide. Short trails (hiking or mountain bike) exist to take you through this surprising lunar landscape!
Footprints of birds
These are traces of birds walking on the beach (sheer the sea was beginning to retreat) 20 million years ago! These footprints are very rare and fragile pieces of geological evidence. This site is closed to the public for security reasons, after a number of landslides in the area took place.
Lame de Facibelle
The Lame or “Blade” of Facibelle is made of sandstone and rises like a peak in the middle of the Velodrome. The result of erosion, the rain has allowed the blade to emerge by removing the layers of softer sediments that surround it. To reach the foot of the Lame de Facibelle, you will cross a suspension bridge to begin the hike. The ascent at the beginning offers you a spectacular view of the Pérouré water gap. Further on, you will recognise the Blade sticking out of the ground. If you continue on the hike, you will reach, at the summit, the hermitage of Saint John and its orthodox chapel (be mindful here to respect the silence of the place). On the descent, you will cross herman de vries’ “Nature Sanctuary” and his inscription “ambulo ergo sum” further down on the path. The trail continues down to the Pérouré tunnel.
This spectacular geological structure is reminiscent of a velodrome, with the Facibelle Blade at its centre. The external edges of the velodrome, made of resistant marine molasses, have been sculpted in a shallow marine environment under the influence of swells and storms. A beautiful hike takes you up to the summit where you can admire this panorama. Along the way, you will come across the works of Andy Goldsworthy and herman de vries in the abandoned village, the Vieil Esclangon, whose history echoes that of the road to Barles, the D900A (DVD in the gîte).
This potable water point between Digne and Barles offers fresh water that springs from beyond the rocks. Its temperature is constant all year round thanks to its deep underground path that protects the water from external variations in temperature. In addition, the thick layer of limestone from the Upper Jurassic period (Kimmeridgian to Tithonian, -155 to -145 million years) is traversed by cracks where rainwater and snow infiltrate and circulate. This layer has been cut by a fault which puts the limestone in contact with impermeable marls (Valanginian and Hauterivian, -140 to -13 million years), and which forces the water to exit here. The site is equipped with picnic tables. Shortly beyond the picnic tables lies a 30 metre waterfall.
Barles Water Gaps
The Bès River makes a spectacular cut into the limestone to form these water gaps. The layers of rock from the Jurassic period which rise vertically above the gushing torrent below can sometimes form real natural barriers. It was not until 1913 that the passage was opened to create the road (D900A) which connects Digne-les-Bains to Seyne. The DVD of the 100-year anniversary of the road to Barles is available at the gîte.
« Saut de la Pie » (The Magpie’s Jump) and the Carboniferous Period
The “piche” (pronounced “pee” in Auzet) means a spurt of water in Provençal. In this narrow gorge, we observe what geologists call a gap or a nonconformity. Here, the sandstones of the Lower Triassic period (-235 million years) rest directly on the black pelite rocks of the Upper Carboniferous (-300 million years). Specifically, the entire Permian layer (-65 million years) is missing. This geological peculiarity is the result of strong erosion and powerful tectonic movements. Not far from here, a set of 42 antique pieces included 27 bladed weapons was found in 1958. It is still being debated as to whether it dates back to the middle of the 6th century BC. They can be seen at the Gassendi Museum in Digne. At the site, you will notice a sign with “0 m” on it. This is part of a contemporary art work by Paul-Armand Gette and refers to the indication of the beginning of something in scientific methods. Here, it refers to the beginning of the Mesozoic era.