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Fosso Marchetto Gorge

Points of Interest

On the summit area of Mount Subasio there are conspicuous karst phenomena due to the permeability of the limestone layers, the almost flat morphology and the presence of faults that have favoured dissolution along well-defined alignments.

Two main types of dolines are identified: sinking dolines, known by the local term 'mortari', and superficial dissolution dolines, known as 'pits'.

Mortaro Grande and Mortaiolo are two deep, almost contiguous dolines. The former has a slightly elliptical shape with the major axis about 270 metres long and the minor axis 220 metres long. Its shape is intermediate between bowl-shaped and funnel-shaped dolines, presenting fairly steep walls and a rounded bottom. The depth is about 60 metres. To the north-east of this large doline is the sub-circular Mortaiolo: its diameter is about 70 metres, the depth is about 20 metres and the bottom is reached after a steep and dangerous descent due to the steepness of the walls, especially in the lower part. Due to the particular shape of this type of depressions, they are referred to as 'goblet dolines'. Another sinkhole is the Mortaro delle Trosce, located about 500 metres north-east of the antennas. It is circular in shape with a cross-section similar to that of Mortaro Grande, the diameter is about 160 metres and the depth is 50 metres.

Among the 'pits', Fossa Rotonda, located about 400 metres north-west of the summit of Subasio, is a flat-bottomed sinkhole, with a major diameter of about a hundred metres, the minor 43 metres and a depth of about 12 metres. It was waterproofed to collect rainwater in order to feed the Vallonica drinking troughs.

West of the summit of Monte Subasio is Fossa Cieca, a bowl-shaped doline with an average diameter of 17 metres and a depth of 4 metres. Also at the bottom of this is a collection pit and a cistern that feeds a drinking trough.

On the Spello side is the lake of Pietrolungo, a flat, wide and slightly depressed doline with a diameter of about 40 metres, at the centre of which a small pool of water remains. The entire doline and the surrounding area have been affected by reforestation, so that the karst phenomenon is currently hardly recognisable.

In addition to the described epigean karst phenomena, the flat top of the relief is dense with other numerous flat-bottomed depressions with highly variable diameters and depths, but which are attributable to surface karst. A very conspicuous valley of karst origin, rising from the Assisian slope, is the Vallonica area. The shape of the landscape reveals the coalescence of dolines smaller than those described so far (uvala). Interesting is the presence of a temporary pool of water in one of these small depressions (along path no. 350 towards Sasso Piano).

Hypogeous karst phenomena are not very frequent, and the fact is attributable to the nature of the limestone rock itself, which has regular stratification varying from a few centimetres to 50 cm. This, however, has not prevented the formation of some cavities in communication with the outside world, mainly represented by five wells, seven caves and two tunnels. The deepest shaft is the one referred to as Grotta del Subasio or Grotta del Diavolo, which opens at 1016 metres near Sassopiano and has a total depth of 30 metres.

Another karstic phenomenon of interest and linked to legends of local tradition is the Orrido delle Carceri. The swallowhole channels seepage waters, collecting them in a large underground cavity. A popular belief holds that it fills with water only on the occasion of wars and particularly important events.

Near Prati Pistello, there is an approximately 10-metre-deep sinkhole entirely in the Scaglia Rossa rock formation (along path 361).

Natura 2000 Network in the Monte Subasio Park
Five Sites of Community Interest (SCI), now recognised as SACs, have been identified in the Park territory, given the different habitats of interest in the area. These areas were conceived for the protection and conservation of natural habitats and animal and plant species. These areas are: Fiume Tescio (upper part); Colli Selvalonga - Il Monte (Assisi); Monte Subasio (summit); Fosso dell'Eremo delle Carceri (Monte Subasio); Poggio Caselle - Fosso Renaro (Monte Subasio).

The Lecceta dell'Eremo delle Carceri is a very interesting example of a high-trunk holm oak forest and has always been protected by the monks who have lived on the mountain since the time of Saint Francis. It is now also recognised as an SAC.

Macchione beech forest
The vast beech forests present in the past are now limited to a few areas, the largest of which is the one known as Macchione, located between Armenzano and Costa di Trex.

Summit meadows are perennial meadows covering an area of 1,190 hectares. These meadows are coloured in spring by numerous flowers, among which is the narcissus, also known as 'the flower of Monte Subasio'. This flower, which is now protected like all other flowering species, was in the past picked on Ascension Day to make up the traditional 'flower bouquets'.

Selvalonga Hills is an area characterised by large wooded extensions of turkey oaks and downy oaks.


On the Tescio river, which marks the northern boundary of the Park, there are numerous bridges from ancient times that served to facilitate both traffic with the neighbouring Marche region and the flow of pilgrims. This secondary road system served to connect the two parts into which the Tescio River divides the valley of the same name and was linked to the presence of numerous water mills in the area. Some of the bridges are:

- St Vittorino (or Vetturino) Bridge from 1283, rebuilt in 1514.
- First Bridge of the Gauls or Molinaccio Bridge (1193).
- Second Ponte dei Galli or Ponte Santa Croce bridge (1353-1357).
- Dolci Bridge (first half of the 19th century).
- Ponte Grande bridge (1469).
- Marchetto Bridge (medieval period).
- Cavaliero Bridge (17th century).

Due to Subasio's rounded shape and its calcareous nature, much of the rainwater descends underground until it reaches the impermeable layers. This is why the waters flow out of the mountain at various levels in the form of springs that man, over time, has managed by building springs and fountains, sometimes also providing for the channelling of the waters and their use in the aqueducts of neighbouring towns.

- Fonte Bregno (on the border between Assisi and Spello)
- Fonte Maddalena (near Costa di Trex)
- Le tre Fontane (near Eremo delle Carceri)
- Fonte Sermattei (located near the abandoned village of Gabbiano Vecchio)
- Fonte del Brecciaro (along the road to Armenzano)
- Fonte San Silvestro and Fonte San Benedetto (located near the abbeys of the same name)

Explore the surroundings
Main attractions in the vicinity