The Penitents of Les Mées

Pebble memory, from collision to destruction

A link in the history of the Alps ... 

Mountain ranges are ephemeral. However, nature "abhors a vacuum", a barely formed relief is intended to be leveled and a basin to be filled.

The young alpine chain in full uplift is then subjected to strong erosion. The materials torn from the mountains are transported and then rolled by rivers and by rivers which deposit them downstream, either in a plain or in the sea.

The Paleo-Durance, Paleo-Bléone, Paleo-Asse, Paleo-Verdon, abandoned them in the former marine gulf of Digne-Valensole. Thus, the coast line retreated towards the south-west with the massive arrival of detrital inputs. The landscape was transformed into a deltaic plain then into a vast alluvial plain far from the marine influence.

These volumes of pebbles, sands and clays formed the enormous mass of the conglomerates of Valensole, part of which forms the current plateau of the same name. If the age of conglomerate formation differs from one point to another, it corresponds as a whole to a time slice ranging from -12 to -2 million years.

Nevertheless, within these conglomerates, there are two groups set up in two stages:

  • the first corresponds to the filling of the marine then continental basin (from -12 to -7 million years ago), called Valensole 1,
  •  the second fills (approximately -5,3 to -2 million years ago) the canyons formed during the Messinian crisis (see box). Named Valensole 2, it is nested in the first and partly covers it.

Even today, geologists still do not agree on the age of the “Penitents” deposit: is it Valensole 1 or 2?

The Pénitents des Mées are a real concentrate of pebbles. Oblique stratifications and bedding are visible in their mass. This organization is the result of the wandering of the channels (furrows dug by a current) in the main river bed and the transport-deposit of pebbles by the currents. The pebbles, sometimes contiguous, are bound together by a scarce but very hard natural cement which gives the whole its cohesion and hardness. The conglomerates of the Penitents took place in the paleo-channels of Durancia.

Today's landscape with its Penitents with conical shapes and sharp ridges is the result:

  • the digging of the current Durance valley during the last glaciation (-90 to -000 years);
  •  then its filling when the ice melts and the sea level rises;
  •  and lastly, the erosion of old conglomerate deposits, whether pre- or post-Messinian crisis.

Learn more about the Messinian crisis and its consequences

5,9 million years ago, the Europe-Africa rapprochement caused the closure of communication zones (Spain-North Africa) between the Atlantic and the Mediterranean.

The Mediterranean is then cut off from a large part of its water supply. The contribution of rivers not compensating for evaporation, its level drops rapidly by 1500 meters, or even more: it is the Messinian crisis.

Towards -5,6 to -5,3 million years ago, the rivers sink deeper to reach the sea level which has become very low. This is the great period of canyon formation in all the peri-Mediterranean regions.

The Gibraltar shoal gave way 5,3 million years ago and announced the end of the crisis. The water from the Atlantic flows in cataracts into the semi-dry basin of the Mediterranean. The sea level rises very quickly, the canyons formed are partly flooded then quickly filled with sediment.

In connection with 22 other geosites: Vélodrome, Ubaye (Pra-Loup-Maurin), Grès d'Annot

The conglomerates of Valensole, which make up the plateau of the same name as well as the Penitents and other surrounding reliefs, are also deposited in part of the Vélodrome. They represent the yellow molasse. Far from the main drainage axes, the deposits are finer, often clayey, which explains the gullied character of the landscape.

In addition, the conglomerates offer a magnificent sample of alpine rocks. Some are of close origin: such as Jurassic and Cretaceous limestone pebbles (Sisteron, Digne, etc.), Annot sandstone (Haute Bléone, Haut Verdon, Allos, etc.), granites and gneiss from the Pelvoux massif (relative du Mercantour). Others are of more distant origins such as serpentinized peridotites, gabbros, variolites from the old ocean floor (Maurin and Chabrière in Haute Ubaye), helminthoid flysch pebbles (Laverq, Riou Bourdoux, etc.).

The composition of the conglomerates reflects those of the mountains being eroded at that time (from -12 to -2 million years ago): all the major tectonic units took place in the Alpine chain, it only remains finish the building ...

What we can decipher from the current landscape

The spectacular appearance of the Massif des Pénitents is due both to its cutting into blades and pointed promontories as well as to the sudden passage of its walls to the wide plain of the Durance.

The Penitents announce the plateaus and reliefs entirely formed of conglomerates of Valensole and which characterize the left bank of the Durance. As for the right bank, it offers a completely different face (colors, shapes, rocks) with the buttresses of the Montagne de Lure. We can recognize a manifestation of tectonics in this brutal transition. Over tens of kilometers long, a wide faulty band structures and cuts up large geographic and geological groups. This section of the Faille d'Aix or Medio-Durancian Accident, inherited from the end of the Primary era (-280 to -250 million years ago) is still active.

This sub-vertical fault materializes the limit between two compartments which are alternately in relief or collapsed (called “normal fault”) or which slide horizontally with respect to one another (“detaching fault”).

 The average annual movement is infra-millimeter. However, it sometimes manifests itself in the form of earthquakes when the stresses are suddenly released. For example, we will recall the earthquakes that marked Manosque in 1509 and 1708.

A little anecdote?

Les Mées or Lei Mèas, in Provençal, is pronounced "Mès" to speak like the ancients. This original pronunciation, however, is lost over the decades ...

"Mées" the name would come from the Latin word "metae" cone, terminal, pyramid and sometimes attributed to a high, pointed point, a visual landmark, like the Mées de l'Estrop at more than 2600m: it is therefore not of "low masses"!

The site of the Association des Amis des Mées ( tells the legend of the Penitents linked to the weakness of the monks facing the beautiful Sarrazines. As punishment, Saint-Donat, the hermit of Lure, petrified them into penitents.

Thus, a new hypothesis on the age of the penitents can be considered:

  • Knowing that Saint-Donat died in 535, the petrification of the monks would therefore have occurred a little earlier. Nevertheless, were the Saracens already in Provence in VIrd century (or later in the VIIIrd)?
  • The Saracens were driven out of Provence at the end of the Xrd century or early eleventhrd.
  •  In the XNUMXth century, the name of the Mees was Metas: this confirms the presence of penitents from that time and its probable anteriority.

 A more in-depth investigation into the Saracens and Saint-Donat is necessary but these first elements of reflection give a range of time between the beginning of VIrd and the beginning of the XIrd century for the training of penitents by petrifying monks.

Geologists and legend-makers might disagree… regarding the case of the Penitents. Tales and legends sometimes give real information about geological events.