Italiano
English Geology of the Gullies
The gully terrain of Lubriano is very fragile, because it is subject to disruption by hydrogeological forces of different types and time periods, caused by the particular lithostratigraphy (rock layering) of the area. All along the southern side of the town of
The rock from which the inhabited area of Lubriano rises is composed of volcanic matter known locally as black “tufo” (a rock compacted from black volcanic waste). The land at the bottom of the valley, however, is characterized by a combination of sand and clay, a seabed from the Pliocene era.
On homogeneous deposits, water carves out furrows that with the passing of centuries become deeper and deeper. Eventually the furrows are separated by steep walls. The result is a series of steep slopes deeply incised by a series of furrows separated from one another by crests shaped like blades. These are the “calanchi” (or “gullies”).
Gullies in Spring - Mirko Pacioni Photo
The greater part of the gullies is formed from very fine and pliable sediments. In this terrain it is easy to find layers of calcite, with crystalline aspects, whose chemical composition is the that of limestone, and one can also find pyrite, rocky outcroppings and chalk. The erosive action on material of variable dimensions, can leave behind spires and towers, usually surmounted by large blocks that protect the sediments below them from erosion. These colourful shapes are often called “earth pyramids”.
The gullies are made up of clay and in winter this type of land is soaked by water becoming particularly subject to landslides. Nearly all the gullies face southward, which allows for a greater exposure to the sun and also favours the formation of fissures of varying depths into which water can easily penetrate. In the gullies the vegetation is very scarce because the flow of water crumbles the land and makes it difficult for roots of plants to take old.