The Geological Museum of Carnia
This interesting museum, part of the Carnia Musei network, is located in the town of Ampezzo, in the val Tagliamento, in the heart of the region of Carnia, the mountainous north-westernmost part of Friuli.
The Museo Geologico della Carnia has been set up following modern and educational concepts: it collects rocks and – in particular – fossils of great scientific value, as demonstrated by the informative panels that allow the visitor to follow the history of the Carnian territory from 450 million years ago up to 40 million of years ago; that is, from the Silurian Sea to the Devonian reefs, and from the Tropical forests of the Carboniferous to the Triassic Seas – all the way up to Alpine orogeny.
In fact, Carnia is one of the few regions in Europe where the geological and paleontological heritage were both preserved intact; therefore, it records the various stages of evolution that took place in this section of the Alps for a period of approximately 400 million years.
Temporary exhibitions of the most varied geological and paleontological subjects are an addition to the permanent displays, especially during the summer months, adding further interest to the visit. The museum is well-equipped with educational facilities such as laboratories, a “game corner” for the young visitors and a rich, well-supplied scientific library.
The Informative Panels of the Museum in Detail
1) “Geological Time” is subdivided into ‘eras’ like the Paleozoic or the Mesozoic; ‘periods’ like the Devonian or the Triassic, ‘epochs’ and ‘ages’ like the Carnian or the Norian. Parcels of rocks with common characteristics are joined in ‘formations’ – deposited therefore in a definite time interval.
2) With the term ‘fossil’ is meant any evidence of past life that comes down to us. That includes for example bone remains of dinosaur, shells of bivalves (but also their imprints), the track of a gastropod or a simple coprolite. Through what is preserved as fossil, even partially, we can reconstruct the main events of the history of life – a very small part of all the organisms that lived in the history of planet earth. That is due to the fact that generally only mineralized parts of organisms (bones, teeth shells, thecae, corals, thalli, etc) have got good preservation potential. Soft-bodied organisms (worms, jellyfish, etc) or un-mineralized parts (insects and even plants) are only fossilized in exceptional circumstances. The most common form of fossilization is mineralization: after death an organism is buried in sediment and incorporated into what becomes sedimentary rock. In the course of a long process, the organism loses its soft parts (dispersed, eaten by necrophagous organisms, or destroyed by putrefaction processes), whereas the hard ones (like bone or shell) are substituted by the surrounding minerals – usually calcite.
3) Rocks cropping out in Carnia are mainly sedimentary; therefore, they are made up of the deposition and solidification of sediments – that is to say of particles, more or less large, of rocky or mineral materials. For example gravel, sand and mud deposited on the sea floor millions of years ago formed conglomerates, sandstone or silt. Accumulations of minerals like calcium, magnesium carbonate or calcium sulphate have formed limestone, Dolostone (or Dolomite) and gypsum. Igneous rocks are rather rare in Carnia; these are formed by the solidification of magma in deep areas (intrusive rocks) or on the surface (effusive rocks – like those originating from volcanic activity). Metamorphic rocks come to the surface only in the western sector of the Carnic Alps (in particular in the area bordering with Comelico). To this category belong the rocks that have undergone significant changes in their internal composition because of intense pressure or elevated heat, but without ‘melting’.
4) Life Swarms in Shallow Waters. The most ancient rocks in Carnia go back to the end of the Ordovician – the second period of the Paleozoic era. These are mainly siltstone (rocks formed from bound fine sand) of grey-green or yellowish colour, known by the name of Uqua Formation. They crop up along the strip of border with Austria – in particular by Casera Valbertad (Paularo) or Ugovizza. These rocks bear up on those of the more ancient bedrock – weakly metamorphosed – of the Val Visdende and the Fleons Formations, mainly outcropping in neighbouring Comelico. The most frequent fossils found here are Bryozoans, Brachiopods, Cystoids and Trilobites – marine organisms that populated the bottom of cold and not very deep seas, situated close to a small continent or an island. When these rocks formed, the climate was moderately cold, because of the ice sheet that covered the current Sahara desert.
5) The siltstone of the Uqua Formation are exposed close to the locality of Casera Valbertad. This is the oldest sedimentary rock in the Italian peninsula, and it goes back to the Upper Ordovician – so they are 450 million years old!
6) The Deepened Sea. At the beginning of the Silurian the sea deepened, also because of the melting of the Sahara ice cap, and the consequent raising of the sea level. Deeper areas of sea basins were formed from the localized sinking of some parts of the earth’s crust. Characteristic of these basins are finely granulated black rocks (argillites and siltstones), easily broken up and rich in Graptolites: colonial organisms that became extinct during the Carboniferous. In other marine areas Orthocerids, Bivalves (typical was the bivalve Cardiola), Gastropods, Brachiopods and Trilobites were common. Towards the end of the Silurian the level of the sea gradually lowered itself again, as evidenced by the grey limestone that formed in shallow waters. Today they outcrop in the area of Monte Zermula (2,143 m).
7) The Silurian deposits crop up at the so-called Costone Lambertenghi (Monte Coglians group): this rock spur is made up of a sequence that includes rocks from the Ordovician to the Devonian.
8) The Silurian rocks crop up mainly along the border with Austria: these are black shale and reddish limestone dating to the Silurian – and the Silurian-Devonian transition. They are present in the area of Rio Malinfier, between Casera Valbertad and Casera Meledis, to the north of Paularo.
9) Coral Reefs and Tropical Seas. During the Devonian, the lowering of the sea level and the tropical equatorial latitude of the Carnia region (at the time) favoured the development of coral reefs. Probably situated in the open sea, far from surfaced land and surrounded by deep marine basins, they are evidenced by calcareous rock layers that exceed a thousand meters above sea level. These reefs are rich in fossils such as Brachiopods, Gastropods, Trilobites, Crinoids, Tetracorals, Tabulates, Stromatoporoids, calcareous algae and Bivalves. Towards the end of the Devonian, the reefs became submerged because of the sinking of the segment of the earth’s crust on which they were to be found. The speed of sinking was such that the depth and therefore the illumination changed rapidly, so the building organisms became extinct. Above the remains of the reefs, very fine deep-sea calcareous sediments – with Ammonoids remains – deposited themselves.
10) Along the high course of the Chiarsò stream (north of Paularo), limestone from the Lower Devonian crop up. They are formed by an alternation of reddish layers a few centimetres’ thick (slow deposition by settling) and thin grey layers (rapid deposition – in a marine basin – at depths of many tens of metres).
11) On the western margin of the Carnic Alps, along the border with Comelico, the massif of Monte Avanza (2,489 m) is made up of Devonian, slightly metamorphic, limestone.
12) The remains of the ancient Devonian reefs crop up from the area of Pontebba as far as Comelico, witnessed also by thick limestone beds. In particular, they form most of the Monte Coglians (2,780 m) group, where they exhibit a typical pale grey to blackish colour, and are rich in fossils.
13) Among Thrusts, Collisions, and Undersea Volcanoes. At the beginning of the Carboniferous period, great quantities of sediments originating from the erosion of distant surfaced lands accumulated in the sea. There were underwater volcanoes from which lava poured out, and it solidified on contact with the water (thus forming the dark basic volcanic rocks of the Dimon Formation). In this period, Africa and North America – in their drift – collided: the rocks on the continental margins, caused by the thrusts, became corrugated and rose out of the sea, thereby forming extensive mountains (Hercynian Chain). In Carnia – and in the nearby Pontebbano area – the Paleocarnic Chain rose up; not particularly high, it was partly eroded and leveled in a relatively short space of time.
14) Volcanic rocks, pillow lava and other deposits connected with volcanic eruptions characterize the area of Monte Dimon (2,043 m). Pillow lava is the structure typically formed when lava emerges from an underwater volcanic vent or as lava flow enters the ocean.
15) The Paleocarnic Chain. After the surfacing phase, the erosion of the Paleocarnic Chain supplied, in its turn, a great quantity of sediments. Transported by water courses, the debris formed wide deltas in the areas of Pramollo and Forni Avoltri, and ended up being distributed in the shallow depths of the stretch of sea that opened towards the southeast. In Upper Friuli, in those times, wide valleys formed with rich tropical vegetation (well testified to by fossil remains), luxuriant above all in the vast levels of the delta. In time, the areas previously occupied by the deltas transformed themselves into shallow seas. The affirmation of the sea environment became generalized towards the middle Permian. Today, this is evinced by widespread calcareous deposits, rich in algae and, locally, in Fusulinids: small single-celled organisms with calcareous shells – the fossil-guide to the Permo-Carboniferous period. In shallow sea deposits are abundant also Brachiopods, Bryozoans, Gastropods, Trilobites and Bivalves.
16) The most interesting Upper Carboniferous fossil-bearing outcrops are exposed in the area of Cason di Lanza (Paularo), continuing to the east up to the Pramollo Pass (1,530 m) and well into Carinthia (Austria) to the north.
17) The contact between the Trogkofel limestone (Lower Permian – light-coloured rocks on the foreground) and the Tarvisio Breccia (Upper Permian – dark rocks in the background) is well exposed at the top of the Creta d’Aip (2,279 m).
18) Among Lagoons and Emerged Lands. The area was subjected to a weak but widespread lifting contemporary with the arrival of a hot and dry climate, and an environment that with the passing of time was transformed into a semi-desert. This geological period is characterized, in northeastern Italy, by outcrops of Val Gardena Sandstone, recognizable by its typical sandstone and red siltstone. In these rocks there are very few fossils, if we exclude rare imprints of vertebrates. Climatic conditions favoured – in the more closed basins – intense evaporation, with the deposition of chalks and decayed Dolomite. These rocks characterize the scenery of some valleys of Carnia (val Pontaiba, val Pesarina), where the phenomena of strong instability of their flanks is associated with them. At the end of the Permian the sea once again invaded the region, leaving as its testimony rocks with fossils of marine organisms (Bellerophon Formation). The end of the Paleozoic era is marked – all over the world – by a mass extinction, leading to a substantial faunal renewal.
19) The Val Gardena Sandstone (Upper Permian) crops up to the north of Ligosullo. This formation represents deposition in a vast dry plain that – around 260 million years ago – occupied the entire area covered today by the Veneto and Friuli regions. A few fossil reptile tracks have been found in Carnia too.
20) Upper Permian gypsum is present in the Ligosullo area. Because of its high erosion, this is easily modeled by Karst phenomena. It is also the originating factor of high geological instability, often causing landslides.
21) The Fossil Beaches. In the Lower Triassic all the region of Carnia was covered by a shallow sea whose level oscillated periodically from some tens of metres to a few centimeters of maximum depth. The rocks of this period (mainly marlstone, siltstone and sandstone) are typically coloured and decidedly spectacular: red, green, yellow and grey (Werfen Formation). They frequently contain fossils: Bivalves, Gastropods, Ammonioides and Marine Starfish (Ophiuroids and Stelleroids). At times, the fossils even conserve the characteristic ripple marks that the wave motion created on the sea floor: their discovery indicates conditions of very shallow waters.
22) Looking at the summit area of the Col Gentile (2,076 m), almost horizontal stratifications are evident, with an alternation between different lithologies (rock types) – lighter and darker, more or less erodible. They belong to the Werfen Formation, which dates to the Early Triassic.
23) Ammonioids and Tropical Seas. Carnia was situated in the western part of a wide sea called the Thetys that inserted itself from the east, separating the two super-continents of Laurasia and Gondwana. These seas presented very different environments: in the shallow and warm waters of the extended carbonated platform were deposited mighty layers of light-coloured limestone formed by the accumulation of carbonates from shell remains, calcareous algae and corals; in deeper waters, thin red calcareous bodies, rich in fossils, deposited themselves. Ammonioides, Orthocerids, Nautiloids, Bivalves, Brachiopods, Gastropods and Ichthyosaurs (marine reptiles) were widespread too. There was even sporadic volcanic activity with outflows of magma (acidic volcanic rock), concentrated in localized sectors (in a special way in the area of Tarvisio and in the surroundings of Ampezzo and Forni di Sotto, in the val Tagliamento).
24) The area of Monte di Rivo-Monte Cucco has been subject to extensive landslides that exposed the Middle Triassic series. The horizontal stratification, the different resistance to erosion of the different lithologies (rock types) and the intense activity of running water produced remarkable pinnacles called ‘Cjampanili dal Lander’.
25) Monte Bivera (2,474 m) is made up of an interesting series of the Lower and Middle Triassic periods. The reddish levels of the Bivera Formation (Anisic) are evident, and the passage to the overlooking Tiarfin Formation (Ladinic) is also remarkable.
26) Lagoons and Shallow Seas. The subdivision of geological time takes its name from the Carnic and Julian Alps because the rocks that formed during this interval of time – the Triassic – were studied here for the first time. The dark limestone, sandstone and marlstone – even with levels of carbon and conglomerates – testify to the lagoon, delta and shallow sea environment; at times, the dry climate favoured the deposition of chalks from the evaporation of the waters. In the lagoons and shallow seas, populated by Bivalves in particular, there were marine reptiles such as Placodonts and Nothosaurs (the first similar in looks to tortoises; the second are tapered predators). In the Carnic sea is in evidence also the presence of cartilaginous fish – much like today’s sharks – which fed on mollusks by grinding them with their flat robust teeth.
27) The craggy Rivolo di Lovea and the northern side of the Creta del Mezzodì (1,806 m): this area preserves the transition between the yellowish deposits of the San Cassiano Formation and the overlying Cassiana Dolostone (or Dolomite) – both of them of Carnic age.
28) The Oldest Flying Reptiles. During this interval of time, the region was situated close to the tropics and, as a consequence, the climate was hot and dry. A marine basin with deep waters slowly formed, encircled in the west, south and east by a platform area with shallow waters, which would periodically emerge to be colonized by plants and land animals. The waters at the bottom of the basin, without oxygen, did not support any life, and the dead organisms that fell to the bottom were saved from the destruction – at work in normal conditions – caused by necrophage organisms and predators, and were thus preserved as fossils. The rocks that formed in this basin are of a dark colour (Forni Dolostone) and contain the remains of vegetation, crustaceans, fish and reptiles; amongst them, are the oldest flying reptiles known in the world (Pterosaurs). The rocks originating from sedimentary mud in the shallow waters of the carbonatic platform (Main Dolomite) are of a lighter colour instead, and contain abundant remains of Megalodonts’ bivalves.
29) The light rocks originating from mud deposited in the shallow waters of the carbonated platform contain abundant remains of Bivalves (Megalodontidae), Gastropods and Stromatolytes. The sediments deposited in these environments (Main Dolomite and Dachstein Limestone) constitute almost entirely the reliefs of Monte Amariana (1.906 m), Mt. Sernio (2.187 m), Creta Grauzaria (2,065 m) and the Monfalconi di Forni (2,453 m) group – the latter already part of the Dolomiti Friulane. Just outside Carnia, in the Carnic Pre-Alps, several footprints of dinosaurs and other reptiles have been discovered too.
30) Rocks originated in the anoxic basin (Forni Dolostone) crop up along the southern flank of the Tagliamento valley, from Villa Santina to Forni di Sopra. They form the north- and northern-western slope of Monte Verzegnis (1,915 m), where the remarkable fossil-bearing area of the Rio Seazza (municipality of Preone) is also located.
31) Not Only Dinosaurs. At the beginning of the Jurassic there existed a situation similar to that of the Noric and Rhaetic, with an area of sea to the north and a platform to the south. Subsequently, the sea deepened also in the southern sector, as shown by the particular types of rock that formed: red oceanic limestone and limestone with flint, which today stand out on the summit of Monte Verzegnis. Quarried and used as ornamental stones, these rocks of a typical red colour present numerous fossils – above all of Ammonites and Belemnites. Isolated teeth of red limestone testify also to the presence of primitive small marine crocodiles (akin to the genus Pelagosaurus).
32) On the top of Monte Verzegnis itself (1,915 m), Jurassic limestone is still quarried. Appropriately worked, it is commercialized worldwide in various forms as ‘Verzegnis red marble’.
33) The Monte San Simeone (1,505 m) is a massif rising between Amaro, Cavazzo Carnico and Venzone. It is made up of Jurassic and cretaceous limestone; incidentally, this mountain was also the epicentre of the disastrous earthquake of 1976.
34) The First Signs of Orogenesis. The rocks of this period jut out in a few places in this mountain region, in part because of the erosion that revealed them, in part because this portion of Friuli was on the way to emerging. In fact, the Alpine orogenesis was underway with the first phase of lifting, and sediments were not deposited in Carnia. In the current Pre-Alpine area, a marine basin bordered by an extensive carbonated platform remains. Cretaceous rocks are widespread in the Pre-Alpine area; they also form the Trieste and Isonzo Karst region (Carso). Common fossils here are the Rudists – typical bivalves of shallow sea in the tropical belt that became extinct at the end of the Mesozoic.
35) The Alps Are Born. At the beginning of the Cenozoic era (Paleocene, Eocene), after the disappearance of the Dinosaurs and Ammonites, the area of Friuli – to the south of current Carnia – was covered by a shallow and warm sea. In this environment were deposited calcareous sediments rich in small organisms, with a husk in the shape of a coin – the Nummulites – and other similar organisms, but flatter and bigger, with an evident spiralization of the shell: the so-called Asselines. The current region of Carnia started emerging during the Eocene: from that moment onwards, this territory became more and more subjected to the intense deformations connected with the Alpine orogenesis, thus becoming an area of prevailing erosion, no more subject to deposition.
36) The Eocene deposits, represented by calcarenites rich in fossil remains of Nummulites, crop up on some areas of Monte Forcella (1,108 m; north of Amaro) and on Monte Plauris (1,958 m) too.