Natural environment

The Abruzzo National Park consists mainly of a chain of mountains whose altitudes range from 900 to 2,000 meters. The mountains have not only the rounded peaks characteristic of the Apennine chain, but also the steep-sided, sharp-pointed peaks more typical of the Alps. The landscape is therefore varied and particularly spectacular.
In the central area of the Park flows the upper part of the Sangro river, fed by various mountain streams. On the outer slopes flow the waters of other rivers like the Ciovenco, the Melfa and the Volturno. Due to the presence of karst phenomena these rivers often flow underground and resurface in the lower valleys sometimes outside the boundaries of the Park.
There is only one natural lake inside the protected area, Lago Vivo, which is small and situated at a fairly high altitude. It is fed partly by its own spring waters and partly by melting snows.
In the past the region was shaped by glaciation and karst phenomena. Glacial cirques are visible in the upper valleys and morainic deposits and rock piles can be seen along the valley floors. The karst formations include caves, gorges and sinkholes.
The rocks of the Park are made of limestone, with loamy and sandy terrain found only in the lower areas of some valleys. Characteristic is the mountain chain of the Camosciara, which is also of dolomitic limestone. Dolomitic rock, being impermeable, means that water flows over it; therefore in this area mountain streams form picturesque waterfalls and rock pools.
The mountains were formed between 170 and 30 million years ago, in the Mesozoic and early Tertiary periods. At one time the Park area was submerged by sea. The limestone rock, in fact, originated from marine deposits typical of lagoon and reef areas, deposits consisting mainly of algae, corals, bivalve mollusks and gastropods. In the course of the various eras the changes have been quite radical.
One geological characteristic of the Park is that various types of sedimentary rock can be found. First, rocks from the area that was once a continental shelf, formed from the sediments of a relatively shallow, muddy sea that was lacking in oxygen and therefore inhabited only by calcareous algae and animals that could survive in such an environment. To the east an area corresponding to the edge of the shelf that once bordered the open sea: here, deeper moving water enriched the sea with oxygen, providing life for many specialized animals whose remains have formed interesting fossils. Finally a transition zone, where a steep slope once joined the shelf with the ocean floor. In this area we find the debris of the fossils of the slope together with deposits from the deeper area.
The Park is highly interesting from a geological point of view.
In the same area there are successive deposits of continental shelf, shelf edge and continental slope. Dolomitic rock - found in the Camosciara, in Val Canneto and on one side of Monte Godi - is extremely old and contains very few fossil remains; it was formed from deposits that built up in the shallow, murky waters of the continental shelf. The final phase of marine sedimentation dates from the Miocene epoch when the area emerged.
Later sediments were formed from the accumulation of river and lake deposits.