Mortari (sinkholes)
Among the most important and clearly visible phenomena are the Mortaro Grande, Mortaro Piccolo or Mortaiolo and the Mortaro of Trosce.
Their name comes from the similarity with the domestic tool, the mortar.
They are located on Mount Civitelle. They have pretty steep walls and a curved base. They are about 50 m. in depth.
The Mortaro Grande is a sinkhole of substantially elliptical shape whose major axis is 260 m. long. It has a depth of 50/60 m. and is the largest of Mount Subasio. Its walls are quite steep. It was formed as a result of the ground’s collapse, caused by the incessant action of water erosion.
The Mortaiolo, adjacent to the first, has a diameter of 70 m. and a depth of about 60 m. and towards the bottom of the walls they are rather steep.
The Mortaro delle Trosce is located in the southeastern part of Subasio, and similar in size to Mortaiolo, it has a rounded shape.
Other Karst phenomena
Orrido delle Carceri  The sinkhole carries the infiltration water which collects in large underground cavities. A popular belief is that it fills with water only during wars and events of major importance.
Bacino carsico di Vallonica (Karst basin of Vallonica) Shortly after the Hermitage (l’Eremo delle Carceri), after the eponymous ditch, at the Refuge Vallonica is the Vallonica basin, a karst area – originally closed – formed by the erosion caused by the same ditch. It is of elliptical shape. Nearby it is also a small well.
Grotta del Subasio (Subasio cave) Situated at 1050 m. above sea level at Sasso Piano, is a well of 18 m. which allows access to a cavity of about 30 m deep.
The lake of Mount Pietrolungo, located along the summit road before Collepino. It is a sinkhole with a flat bottom well and water on the bottom, hence the name.
On Mount Subasio there are numerous depressions
The Fossa Rotonda is a complex elliptical shapes sinkhole which is located north-west of the top of the relief. The larger diameter is about 100 m, with a depth of 12 m.
• Not far away is the Fossa Cieca, with a 17 m. diameter.
Depressions Mortaro Grande and Mortaro Piccolo were for centuries a reserve of ice, serving the function of real refrigerators. The snow that fell there during the winter was compressed into the sinkholes so that it could last longer and, if necessary, was cut into blocks, transported downstream and then sold for food storage.
“Text taken from the Mount Subasio Park, © Quattroemme, Perugia 2006. All rights reserved”
Forra di Fosso Marchetto (Gorge of Fosso Marchetto)
Gorges carved by the waters of Fosso Marchetto. The practice of canyoning in this place is for everyone to enjoy the spectacle of the canyon as it does not require any special equipment for the absence of significant jumps. However, it needs a diving suit and the accompaniment by a qualified guide for beginners.
Lecceta dell’Eremo delle Carceri (Holm Oak Hermitage)
It is a very interesting example of tall holm oak wood and has always been protected by the monks who lived on the mountain from the time of St. Francis.
Faggeta del Macchione (Beechwood of Macchione)
Extensive beech forests in the past are now limited to some areas, the largest of which is known as the Cacchione located between Armenzano and Costa di Trex

Prati sommitali (Summit Meadows)
There are perennial grasslands that extend over an area of 1,190 hectares. Such spring meadows are colored by numerous flowers among which is the narcissus, which is somewhat considered the flower of Mount Subasio. This flower, today protected like all other floristic species, in the past was collected on the day of Ascension to compose the traditional “bouquet of flowers”.
Colli di Selvalonga (Hills of Selvalonga)
Area characterized by large wooded extensions Turkey oak and Downy oak.