Sicily

The research on the Sicilian chert formations makes use of the baseline provided from the literature (Catalano et al. 1984, 1989; Lentini, 1984; Lentini et al. 1995) and follows the suggestions of Professor Pedley (University of Hull), Prof. Maniscalco (University of Catania) and Prof. Di Stefano (University of Palermo) who are experts on Sicilian geology. The search for chert sources was focused on three provinces: a) Ragusa, b) Enna and c) Palermo. The details with the exact location of the samples and their macroscopic characteristics can be found in the Appendix I (Table 2 and 4).

➢ Province of Ragusa

This province is located in the southeast part of Sicily and consists only of the formations of the Hyblean Plateau (Fig. 2.16). The chert outcrops are found in the Ragusa Formation and the investigation was conducted in a triangular area among the towns of Comiso, Monterosso Almo and Modica (Fig. 5.7). This area is also crucial for this fieldwork as it presents evidence of prehistoric mining activity (Vella, 2008) and it may have been a location from which chert material was exported to Malta.

An established location with such activities is Monte Tabuto (mountain) which was the prime area investigated. Monte Tabuto is located between Comiso and Ragusa (Fig. 5.7-8) and the first prehistoric mines were found along the main road which leads to the top of the mountain (Fig. 5.9a). The fieldwork in this area revealed that the mining structures are not restricted along the road but spread across the whole west side of the mountain. The chert outcrops, however, are very limited and scattered, while no chert source has been reported in the mines. The first chert outcrops are in nodular form with a thickness between 6 to 8cm (sample S1) and were found beside a mine entrance (Fig. 5.9c, d). Further exploration of the area has shown that the chert outcrops vary in size and shape, while occasionally they form small layers (< 5 cm). They generally have a brownish colour but the greater nodules (reaching 35cm diameter) present black or dark olive-grey cores (Fig. 5.98b). Continuing away from the mines, downhill or uphill, the chert outcrops rapidly decrease and finally disappear within a couple of metres. The research continued into the area around the Ragusa Town, which on the geological map presented the same geological formation as at Monte Tabutto. However, the investigation in this area has not recorded any indication of chert outcrops and the research therefore moved to other locations.

The next stop region was south of Modina Town (Fig. 5.7-8), which presented mainly the Irmino member (Lower Miocene) of the Ragusa Formation. The chert outcrops are in small nodular form, but they occasionally form beds of 5 to 10cm in thickness. They are described as fine-grained, translucent and present dark brownish colours.

83

Figure 5-7: Map of SE Sicily recording the main towns and location of the area (Maps Copyright @2016 Google).

Figure 5-8: The Geological Map of SE Sicily by Age and the main sample locations.

84

Figure 5-9: a) An entrance of prehistoric mine, b) Chert outcrops close to the mine presented at a, c) Chert outcrops beside another prehistoric mine, and d) detail of c.

The final stop was near the town of Monterosso Almo (Fig. 5.7-8) which is located at the northern part of the province. This area has provided the opportunity to investigate almost the whole succession of the Hyblean Plateau. The geological formations which are found in this location extend from the Cretaceous (Campanian) to the Quaternary. The first chert outcrops are located in an old quarry along the road which connects the town with the Licodia Village. This quarry is in the lower part of the Armerillo Formation (Cretaceous) which is known to contain chert outcrops (Lentini, 1984). Starting from the entrance of the quarry (Fig. 5.10a), greyish nodular cherts intercalate with the limestone (Sample S15). These cherts vary in size and have chunky forms, while others form thin beds (2–3 cm).

Moving to the inner parts of the quarry and following the left slope (Fig. 5.10b), these horizons become more distinct and are divided into two main groups. The lower group has greyish colours and a thickness between 3 to 6cm, while the upper group is thinner (2.5 cm), more fine-grained and has a dark brownish colour (Sample S14). The latter is not found in any other part of the quarry and is part of an exposure of several metres in length. The centre of the quarry presents an extensive profile (approximately 100m) of the Amerillo Formation (Fig. 5.10c) with multiple bedded chert outcrops (sample S13). Although they are very similar to the lower group of the previously described cherts, they are thicker (10 cm), denser and have a blackish colour on the upper parts (sample S17). During the investigation of the quarry, indications were recorded of another type of chert outcrop. This is

85 suggested from scattered pieces (cores and fragments) collected and examined in the quarry which are not in situ (sample S16). The investigation has not found their source and the in situ examination of the outcrops has not been possible. These pieces are thick (10cm), very strong (difficult to break even with the hammer), have a brownish grey colour and a completely different texture from the chert outcrops in the quarry.

The investigation for more chert sources continued along the road to Licodia Village, which presents exposures of the upper part (Eocene) of the Amerillo Formation. The examination of this Eocene limestone found very thin layers and lenses of chert (Fig. 5.11). These chert outcrops are divided into 3 or 4 distinctive horizons, which are 30 cm in length, 4 to 6cm in thickness and characterized by a brownish to black colour (Sample S18). The examination of this formation has been interrupted by the unexpected presence of a conglomerate outcrop. It is highly possible that it is an outcrop of the Pliocene brecciated formation (Pb), which has exposures in nearby locations (Lentini, 1984). Although this interruption is unexpected, it has provided some very interesting and new information. This conglomerate outcrop is a soft and sandy formation, with different sizes and shapes of breccias. Some of these breccias are actually chert pieces, which are easily extracted with the use of a lever. In addition, this formation presents man-made structures (Fig. 5.12a, b) similar to the prehistoric mines at Monde Tabuto. In fact, a chert sample was collected (Sample S19) for further investigation in precisely one of these structures (Fig. 5.12b, c).

Moving along the road, the Amerillo Formation (limestone) is found again, but this time presents slightly different chert outcrops. They are not divided into distinct horizons as before, but they form huge and irregular shaped nodular cherts (Fig. 5.12d; Sample S20). The majority of the nodular cherts are 7cm in thickness and 12cm in length, while the largest reaches 12cm in thickness and 15cm in length. Some lenses which exceed 45cm in length were also located, but they do not differ in any other macroscopic characteristic (Fig. 5.12e, f). The final stop was made just before the entrance of the active quarry, but again in the Armerillo formation. Important chert outcrops were located there, which are very different from the outcrops already examined. They are huge and thick cherts in nodular and lens forms with irregular shapes (Fig. 5.13) and are greyish-red to orange in colour (Sample S21). The investigation of the other formations in the area did not present anymore chert outcrops and therefore the investigation of the Ragusa province was completed.

86

Figure 5-10: Chert and silicified limestone outcrops south of Modica Town in SE of Sicily.

Figure 5-11: Black to brownish chert lenses outcrops, which are found intercalating the Amerillo Formation (Eocene).

87

Figure 5-12: a) The road leading to Monterosso Almo town, where the man-made structures were found (on the left), b) The entrance of one of these structures, c) Detail of b where chert pieces were located (arrows), d) huge nodular chert

with chalky residues, e and f) chert outcrops in lens form.

88

Figure 5-13: a) The Amerillo formation with the huge and thick chert outcrops, b) detail of a, focusing on a huge lens of brownish chert.

➢ Province of Enna

The next region is the province of Enna, which is located northwest of Ragusa province (Fig. 5.7-8) and has significant chert outcrops (Carbone et al., 1990). These outcrops are found in the formations of the Monte Judica unit (Carbone et al., 1990). Regarding their place in the geological time, they extend from Carnian (Triassic) to the Upper Serravallian (Miocene). The investigation started from a place called Contrada la Vina, which is close to the Valona River and presents significant exposures of the “Calcari con Selce” formation. This Triassic limestone formation (Carnian to Upper Rhaetian) includes fragmented nodular cherts of different sizes and shapes (Fig. 5.14a, b) and two representative samples were collected (samples S4 and S5).

The next stop is at the Valona River riverbed, where exposures of the Radiolarian formation (Jurassic – Cretaceous) are found (Fig. 5.14c, d). The formation has huge exposures on both sides of the river which expand to several metres thick (Fig. 5.15). It consists of a sequence of radiolarian beds with different thicknesses and colours varying from red to green (Fig. 2.19a, b). Occasionally, the sequence is interrupted by thin intermediate layers/horizons of silicified limestone beds. The thin horizons have green or dark red colours, while the limestone has greyish to red colours and a thickness which varies from 5cm to 17cm. The lowest radiolarian bed is a solid and dense layer, which has a reddish colour and is 6cm thick (sample S6). This is followed by a thicker (12cm) red to green bed (sample S7), which is fragmented and weathered. Above that, the outcrop presents alterations of thinner radiolarian beds (2 to 5cm) and silicified limestones (5cm). The middle of the radiolarian succession consists of thicker beds with the silicified limestones reaching 17cm and the radiolarians 13cm in thickness, respectively. The radiolarian beds present distinct macroscopic characteristics and have been sampled (sample S8) for further investigation. The rest of the outcrop to the top is characterized by weathered, red and thick radiolarian beds alternating with thin silicified limestones.

89 The research then moved to a location called Monte Santo (Fig. 5.7-8), where more exposures of the “Calcari con Selce” formation are found. This exposure differs from the previous one (Contrada la vina) because it presents well developed, black, bedded chert outcrops (Fig. 2.19c, d). Three samples were collected from the most representative zone (sample S9, S10, S11) and the stromatographical order (first sample from the lowest bed) was recorded.

Figure 5-14: Chert outcrops in the broad Valona River area. a and b) Fragmented Triassic nodular cherts, c and d) Bedded Radiolarian outcrops.

Figure 5-15: The exposure of the of the Radiolarian formation along the Valona River from a distance.

90

➢ Province of Palermo

The research continued into West Sicily and investigated the province of Palermo (West Sicily), which is geologically also known for chert outcrops (Catalano et al., 1978; Catalano 2004; Di Stefano et al. 1992; Di Stefano et al. 2013). The first stop was made at a sanctuary called “Madona del Balzo”

(Fig. 5.16), located on the top of Triona Mountain (elevation 899cm). The sanctuary is built on a limestone formation (Formazione Scillato), which is part of the Del Bacino Sicano unit (Fig. 5.17) and is very similar to the “Calcari con Selce” formation of the Monte Judica unit (province of Enna). This limestone is of Upper Triassic age (Upper Carnian to Lower Rhaetian) and the exposure beside the sanctuary presents chert outcrops. They are small nodular or lenses outcrops, highly fragmented, with irregular shapes and very difficult to extract (Fig. 5.18a). Nonetheless, two representative samples (sample S22) were collected, which presented different macroscopic characteristics.

The next stop was located on the Genuardo Mountain (elevation 883m), very close to the Santa Maria del Bosco (monastery), and where the homonymous limestone formation (Calcari Di Santa Maria del Bosco) was examined for chert outcrops. The investigation found black bedded cherts (Fig. 5.18b) which are approximately 6 to 10cm in thickness (Sample S23). Continuing west of these black chert outcrops, indications of a new chert outcrop were found which differ significantly from any other chert formation previously examined. Plenty of scattered pieces of a dense, heavy and solid yellowish chert (Fig. 5.18c) were found lying on agricultural fields. The macroscopic characteristics of these pieces indicate that this chert formation must be related to the basaltic lavas which are recorded on the geological map (Di Stefano et al, 2013) of the area. These volcanic formations should be intercalating between the “Calcari Di Santa Maria del Bosco” (below) and the “Formazione Barracu” (above). The in situ examination of this outcrop was unsuccessful, mainly because the whole area is under private ownership which prevents any type of investigation. Therefore, it was decided to collect just one of the scattered pieces (Sample S24) as evidence and for further laboratory research.

Finally, moving along the same area, the research located several exposures of the “Formazione Barracu” (middle–upper Jurassic). It is a highly silicified limestone intercalating with greyish bedded chert (Fig. 5.18d). The chert outcrops present a significant amount of carbonate residues and the beds are 4 to 6cm in thickness (Sample S25).

91

Figure 5-16: Map of West Sicily recording the main towns and location of the area (Maps Copyright @2016 Google).

Figure 5-17: The Geological Map of West Sicily by Age and the sample locations.

92

Figure 5-18: a) Fragmented nodular chert outcrops at "Madona del Balzo", b) Black bedded chert outcrop close to Santa Maria del Bosco (monastery). C) Pieces of the yellowish chert formation, d) greyish bedded chert outcrops intercalating

with a highly silicified limestone.

93