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Located between the provinces of Parma and Piacenza, near the built-up area of Salsomaggiore Terme, the Stirone river site represents an important window on the geological evolution of the Emilian Appennine, like the near Arda River. Because of the strong fluvial erosion linked to the mining activity carried out between 1950s and 1960s, it is actually possible to have direct access to sedimentary successions, and the related fossils, dated back to the last 80 millions of years. It is therefore possible to follow the evolutionary history of these successions simply by following the riverbed.

Starting from the oldest rocks, outcropping near the small church of San Genesio and dated back to a period ranging from 80 to 55 millions of years ago, and moving along the river up to Fidenza, a sequence of progressively younger strata is present, ending with Middle Pleistocene sediments. Despite some gaps, this sequence allows to travel through the main events characterizing the geological history of the area in the considered time range. The Cretaceous-Paleocene rocks are part of the allochthonous substrate of tyrrhenian origin (Liguride rocks) that has been pushed towards the current position from the Oligocene onwards because of the counterclockwise rotation of the Sardinian-Corsican Block, during the formation of the Appennines. This movement continued until the middle/upper Miocene, when turbiditic successions deposited in the foretrough basin and sedimentary layers deposited in small basins formed over the deformed Liguride units. These sediments, part of the so-called Epiligurid units, crop out near the locality of La Bocca. The absence of the Gessoso-Solfifera Formation in the riverbed hampers the observation of the effect of the Messinian Salinity Crisis. The Epiligurid units are here ended by fluvio-lacustrine sediments of the Colombacci Formation (upper Messinian; roughly between 5.6 and 5.35 millions of years ago) followed by marine sediments (Lugagnano Formation; 5.3-3.6 millions of years ago), which testify for the restoration of deep marine conditions in the Stirone area during the Zanclean. The remaining part of the marine succession, however, shows evidence of a progressive cooling and of a regressive phase, as demonstrated by the appearance of cool temperate species and boreal guests such as the bivalve Arctica islandica downstream of the small church of San Nicomede. The following passage to purely continental deposits, visible near Laurano, is recorded by the roof of a pack of sandy sediments characterized by sedimentary structure typical of a water edge environment significantly named locally as “the Last Beach”.

Fossils from the Stirone

The fossil record of the sediments outcropping in the Stirone riverbed is rich and diverse. It includes plant remains, trace fossils, invertebrate and vertebrate remains. Extremely abundant are the invertebrates and particularly the molluscs: levels provided with a rich content of pectinids and other bivalves are present, but gastropods such as Astrea fimbriata, Natica tigrina e Xenophora testigera or corals as Asterosmilia prolifera have been also found. Particularly interesting are the communities of lucinid bivalves present near the locality of La Farfanara, probably linked to the proliferation of sulfate-reducing bacteria (which create a symbiotic relation with the lucinids) in an environment with methane- and hydrogen sulfide-rich fluids coming out from the sea bottom. Vertebrates are less common and represented mostly by fish. As far as the mammals are concerned, remains of Miocene cetaceans and Pleistocene rhinoceroses have been found. The former include the holotype of the fin whale Plesiobalaenoptera quarantellii, whereas a very well preserved skull of Stephanorhinus hundsheimensis is remarkable among the latter. A single reptile, a marine turtle assigned to the species Trachyaspis lardyi, comes from Pliocene-aged diatomaceous levels outcropping near La Farfanara. Most of the fossils coming from the Stirone are currently stored in the Palaeontological Museum “Il Mare Antico” in Salsomaggiore Terme, whose collections have been largely increased by the contribution of the palaeontology enthusiast Raffaele Quarantelli.

Further reading

Bisconti M. (2010). A new balaenopterid whale from the Late Miocene of the Stirone river, Northern Italy (Mammalia, Cetacea, Mysticeti). Journal of Vertebrate Paleontology 30: 943-958.

Cau S., Franchi F., Roveri M. & Taviani M. (2015). The Pliocene-age Stirone River hydrocarbon chemoherm complex (Northern Apennines, Italy). Marine and Petroleum Geology 66: 582-595.

Dominici S. (2001). Taphonomy and Paleoecology of Shallow Marine Macrofossil Assemblages in a Collisional Setting (Late Pliocene–Early Pleistocene, Western Emilia, Italy). Palaios 16: 336–353.

Esu D. (2008). A new species of Tanousia Servain (Gastropoda, Hydrobiidae) from the Early Pleistocene of Emilia-Romagna (Northern Italy). Bollettino della Società Paleontologica Italiana 47 (1): 45-49.

Garassino A. & De Angeli A. (2004). Decapod crustacean fauna from the Pliocene and Pleistocene of Arda, Stirone and Enza rivers (Piacenza, Parma and Reggio Emilia Provinces, N Italy). Atti della Società italiana di scienze naturali e del Museo civico di storia naturale di Milano 145 (I): 29-57.

Gregor H.-J. (1986). Preliminary report about the macrofloral history of the Stirone-river sequence (Zanclean, Piacenzian, Calabrian). Memorie della Società Geologica Italiana 31: 219-227.

Gunderson K.L., Kodama K.P., Anastasio D.J & Pazzaglia F.J. (2012). Rock-magnetic cyclostratigraphy for the Late Pliocene–Early Pleistocene Stirone section, Northern Apennine mountain front, Italy. Geological Society, London, Special Publications 373, doi: 10.1144/SP373.8.

Marasti R. (1973). La fauna tortoniana del T. Stirone (limite Parmense-Piacentino). Bollettino della Società Paleontologica Italiana 12 (1): 76-120.

Pervesler P., Uchman A., Hohenegger J. & Dominici S. (2011). Ichnological record of environmental changes in early Quaternary (Gelasian-Calabrian) marine deposits of the Stirone section, northern Italy. Palaios 26: 578-593.

Raineri G. (2007). Il Parco dello Stirone… Un Museo all’Aperto. Le rocce e i fossili raccontano…. Consorzio Parco Fluviale Regionale dello Stirone, Salsomaggiore Terme (PR).

Regione Emilia-Romagna (1997). Parco Regionale Fluviale Stirone. 197 pp. Giunti Editore, Firenze.

Villa A., Raineri G. (2015). The geologically youngest remains of Trachyaspis lardyi Meyer, 1843 (Testudines, Cheloniidae): a new specimen from the late Pliocene of the Stirone River (Northern Italy). Bollettino della Società Paleontologica Italiana 54: 117-123.

On the web

Parco dello Stirone e del Piacenziano

Text by Andrea Villa

Photographs by Andrea Villa, Giuseppe Romeo, Stefano Dominici

(partially in English)