• Valle d'Aosta

• Regional Nature Reserves

• Alps

The Reserve

Established in 1993, Mont Mars Regional Nature Reserve covers an area of 390 ha on the left bank of the lower Valle del Lys. It is situated in the Municipality of Fontainemore, at the head of the valley crossed by Stream Pacoulla. The Reserve develops between the 1,670m and 2,600m of altitude, and is characterized by a variety of alpine environments of great interest:

• forests alternating with meadows
• alpine grasslands
• from heaps of stones to rocky walls
• lakes
• wetlands

Further information (Italian text)

Geology

Rocky substratum

The territory within the Reserve is included in the bibliography as "zona Sesia - Lanzo" and in particular in the "inner" stratum mainly characterized by eclogite mica schists. In the bibliography such rocks have been further divided according to the presence of prevailing and evident minerals (garnets, etc.).
The orogenetic tectonics has enabled to incorporate in the prevailing lithology some relicts of the "Piedmont stratum of Greenstone Calcareous Schists" as well as isolated lens of impure marbles.
Evidences of the former can be found in outcrops of modest size within which there are lithotypes of the substratum (amphibolite, etc.) and of the mixed calcareous terrigenous covering (calcareous schists) often associated to the enclosing mica schists without a break (calcareous mica schists).
The plicative structures of the outcropping scale are often well-evident.
The marbles probably derive from calcareous structures forming in a marginal marine environment and incorporated in the mica schists of the "Sesia - Lanzo unity" within which you can find modest-size outcrops.
In the Quaternary period the morphogenesis - glacial at first and torrential afterwards - has placed over the original structures of the rocky substratum the typical forms of the glacial environment and in a subordinate manner those of the periglacial environment. Therefore, you can recognize both the moutonnée rocks of the main valley slopes and the well-preserved overexcavation rocks which are currently filled with lacustrine basins (Barma, Lei Long, etc.) alternating with spectacular (almost didactic) glacial moutonnée rock steps.
The fracturing degree of the rocky heaps varies from scarce small-size outcrops of rocks presenting almost no fissures to the real areas of deep gravitational deformation (DGPV) recognizable thanks to the presence of upset heaps near watershed ridges or double ridges.

Surface Formations

The geological environment of the reserve preserves the relicts of the landscape of the glacial structure to which the action of the watercourses superimposed but did not conceal the evidences.
The heaps of angular detritus deposits of various size with associated boulders which sometimes can be of some cubic meters are the result of the accumulation by the glacier (lateral moraine), but also of the periodical fall of the overhanging rocky walls. Therefore, the difficult interpretation could lead to a definition of a wrong genesis for such lithologies which have been described according to the size of the blocks forming it and to the presence or not of vegetation, but not to their genesis.
Some isolated boulders which have been found in a position tracing them back without a doubt to the glacial action have been described as erratic boulders.
Where the glacial mass has not intervened with the ice abrasion, and where slopes are not so steep, the sides have had the possibility to produce a colluvial covering of a few centimeters of thickness, allowing the growing of herbaceous vegetation. Also at the bottom of the valley the alteration of the materials present in the outcrop has allowed the growing of herbaceous vegetation after the withdrawal of the glacier.
The forms of glacial overexcavation have been filled up by the current lakes, some of which are in an advanced state of eutrophication (Lei Long, …) and therefore, the marshy deposits in the areas surrounding some lakes have been described. Such descriptions will be soon completed and published.