A submerged monolith in the Sicilian Channel (central Mediterranean Sea): Evidence for Mesolithic human activity (original) (raw)

Introduction

An abundant number of archaeological and geological data acquired in several coastal areas of the Mediterranean Basin represent the evidence that it has undergone major changes in sea level during the glacial-interglacial cycles (e.g., Lambeck and Chappell, 2001, Lambeck and Purcell, 2005, Antonioli et al., 2009, Auriemma and Solinas, 2009). After the Last Glacial Maximum (LGM), around 19,000

year

B.P., when the land area of Europe was ~

40% larger than it is now, a relatively abrupt global rise in sea-level took place, estimated to be of 125

±

5

m, as determined by correcting observed sea-level changes for glacio-hydro-isostatic contributions (e.g., Fleming et al., 1998, Mix et al., 2001, Siddall et al., 2003, Lambeck et al., 2004, Clark et al., 2009).

The Sicilian Channel is one of the shallow shelves of the central Mediterranean region where the consequences of changing sea-level were most dramatic and intense, as also occurred in part of the Aegean Sea, the northern Adriatic, and the Tunisia and Malta platforms. The Sicilian Channel is geologically part of the northern African continental shelf (Fig. 1) and lies mostly under shallow water, with the exception of three NW-trending, relatively deep troughs (the Pantelleria, Malta and Linosa grabens) produced since the Early Pliocene by rift-related processes (e.g., Reuther and Eisbacher, 1985, Boccaletti et al., 1987, Cello, 1987, Civile et al., 2010). This tectonic extension was also responsible of the formation of the two volcanic islands of Pantelleria and Linosa, and other submerged volcanic edifices lying along the eastern margin of the Adventure Plateau (Calanchi et al., 1989, Rotolo et al., 2006, Lodolo et al., 2012). It occupies the north-western sector of the Sicilian Channel, where available oil exploratory wells have shown that the sedimentary sequence ranges from Triassic to Plio-Quaternary, with various hiatuses associated with long periods of aerial exposition and/or erosion (Civile et al., 2014). The Adventure Plateau is the shallowest part of the entire Sicilian Channel, and is punctuated by several isolated banks, some of them rising up to less than 10

m below sea level (Colantoni et al., 1985). During the LGM, the Adventure Plateau was part of the former Sicily mainland, forming a peninsula (the Adventure Peninsula) bulging towards south into the Sicilian Channel, and separated from the North African coastline by less than 50

km. The gradual increase of the sea level caused the flooding of most of the peninsula, with the exception of some morphological highs that, until at least the Early Holocene, formed an archipelago of several islands separated by stretches of extremely shallow sea, as shown by the analysis of swath bathymetric mapping and high-resolution seismic profiles (Lodolo, 2012, Civile et al., 2015). Today, the Adventure Plateau is morphologically separated from Sicily by the Mazara del Vallo Channel (depth of about 120

m), and from Tunisia by the Pantelleria graben (depth of about 1300

m).

It is well known that the Mediterranean Sea is a unique basin from a historical and archaeological perspective, since it was an important means of communication among human communities living on its shores. These ancient civilizations have left numerous imprints along the former coasts, such as production and town structures, landing places, and ports. Some structures that are today submerged can provide fundamental information to support the reconstruction of the ancient coastlines (Auriemma and Solinas, 2009). Conversely, in shallow water areas distant from the coastline, the information on possible ancient permanent human settlements are scarce, and there are no traces to date found in the Mediterranean Basin mainly because the lack of detailed and extensive bathymetric mapping, and the presence of a variably thick sedimentary cover masking any submerged structure.

Here we present the results of high-resolution bathymetric surveys performed on the Pantelleria Vecchia Bank (PVB), a submerged shallow relief of the Adventure Plateau, located 40

km north of the volcanic island of Pantelleria, as well as underwater visual observations by divers, analyses of some rock samples collected in several locations of the bank, and radiocarbon dating. These data provide evidence for an unique and significant structure of anthropogenic origin.

Section snippets

Methods

Detailed sea-floor surveys were conducted in November 2012 using a hull-mounted multi-beam sonar system with the R/V _OGS_-Explora. Subsequently, in December 2012, a high-resolution survey was focused on a specific area of the PVB, which was mapped with a portable multi-beam sonar system. These surveys provided a context for direct sea-floor observation made by divers, who recorded high-definition video (for a total of approximately 8

h of registration) and photos, and collected several rock

High-resolution bathymetric maps and underwater surveys

The bathymetric map (Fig. 1) reveals that the PVB is made up of two main shoals, intersected by fractures and steep valleys, and a number of smaller isolated bathymetric highs, covering a total area of 5.2

km2, with little or no sedimentary cover. The present depth of the two main shoals varies from 16 to 24

m, while the surrounding areas are located at depths ranging from 46 to 60

m. Here, the unconsolidated sedimentary cover of the bedrock is composed of coarse organogenic sands with thickness

Interpretation

From the data we have here presented and analysed, it can be inferred that the monolith discovered in the PVB is not a natural feature, but man-made. The elements that combine to formulate this interpretation can be listed as follows:

Discussion

The obtained age for the PVB site places it within the beginning of the Mesolithic. Perhaps the most important archaeological discovery of the Mesolithic age is the monumental temple complex of Göbekli Tepe, situated in south-eastern Turkey. Carbon-dated to about 11,600

year

B.P., this site is believed to have been a religious centre or sanctuary (Mann, 2011) serving a well-organized settlement (or series of settlements), as evidenced by its diverse range of megalithic art, as well as the large

Acknowledgements

This research is part of a joint Italian-Israel scientific project financed by the Italian Ministry of Foreign Affairs (grant 3697715AF0). The technical and scientific party of the R/V _OGS_-Explora contributed in acquiring the data. Daniela Accettella, Andrea Cova, Emiliano Gordini and Diego Cotterle processed the high-resolution bathymetric data. Franco Coren has provided the logistical support for the activities at sea. Special thanks go to the personnel from the Arma dei Carabinieri who

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2018, Environmental Pollution
The Pantelleria Vecchia Bank, composed of carbonates and sandstones, is located at about 20 miles north of Pantelleria Island. It is made up by two main shoals, varying from 16 to 24 m depth whereas the contiguous areas range from 46 to 60 m depth (Lodolo and Ben-Avraham, 2015). The Graham Bank is in turn made up by several volcanic structures, such as the ephemeral Ferdinandea Island, which range from 9 to 250 m (Falzone et al., 2009; Rovere and Wurtz, 2015).

2017, Marine Environmental Research
This Bank is located 20 nautical miles north of Pantelleria Island. It is composed of two main shoals, ranging from 16 to 24 m b.s.l., and a number of smaller isolated bathymetric highs (Lodolo and Ben-Avraham, 2015). In order to demonstrate that the investigated banks represent hot spot of biodiversity under threat, a multidisciplinary approach was adopted, referring to both the methodology used and the issues investigated (biological/ecological traits, threats and pressures). View all citing articles on Scopus

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