4.1. The Pantelleria Vecchia Bank Site
Already in 2015, Tusa et al. [
69]. published a detailed rebuttal (in Italian) of the Lodolo and Ben-Avraham [
59] paper, presenting extensive geomorphological, contextual and archaeological data to refute their claim of having found a large anthropogenic megalith. However, Lodolo and Ben-Avraham were apparently unconvinced and presented the same arguments in two additional articles [
58,
60]. Consequently, we have felt compelled to re-examine the issues raised by Lodolo and colleagues relating to the anthropogenic nature of their finds. With reference to examples from the Mediterranean coast, we explain why in our view (and as previously noted by Tusa et al.) [
69], the rock formations they describe on the Pantelleria Vecchia Bank, do not support their claim that these are human-made constructions, but rather confirm that these are natural features.
Based on the thin sections shown in the publications of Lodolo and colleagues, they proposed that both Ridge 1 and Ridge 2 are composed of bioclastic rocks, (either beachrock or consolidated beach deposits), and that the elongated Ridge 1 that blocks the submerged bay, is probably a beachrock that was consolidated and embedded in the intertidal zone during a low sea- stand, some 45-50ka BP, as the 14C dates indicate. This interpretation is supported by the sea-level curves [
70,
71,
72], suggesting that the sea bottom in the Sicilian Channel was dry land between ca. 75,000 to 10,000 BP. It is emphasized here, that the dates presented by them, reflect the timing of beachrock consolidation and not that of suspected anthropogenic activities.
Beachrock is a common formation in the Mediterranean Sea and often forms on sandy coasts. As already noted by Tusa et al. [
69], beachrocks (our translation from Italian follows)
"often detach from the rocky basin of origin due to coastal erosion, depositing themselves in the Mediterranean Sea between +1 and -5 meters with respect to the coastline (they are known and dated up to a depth of 60 meters in Sardinia, Turkey, Sicily, Greece, Croatia and Liguria)" for example see [
73,
74]. Thus, various features and patterns resulting from coastal erosion of beachrock and beach deposits (e.g., chimneys, detached rectilinear blocks) are common in coastal environments.
Vertical earth crust changes due to tectonic activity, isostasy or structural changes, may have changed the relative sea level in the research area. However, given that the area is considered relatively stable [
56] such changes, if they occurred during the Holocene, would have only have resulted in a displacement of a few meters. Thus, the height of the reported finds relative to sea level, and the deposition and erosion processes of the beachrocks under coastal/shallow marine conditions, have not changed considerably. Notably, according to the sea-level curves, the two stone ridges were exposed to coastal/intertidal/shallow marine conditions circa 10ky, 75ky and possibly 50ky before present (
Figure 13: 1, 2, 3). We contend that during these events, the beachrock Ridges most probably underwent significant erosion resulting in the rectangular forms observed.
Ridge 1 is currently located in situ, at the site of its deposition. Thus, the most parsimonious explanation for the presence of the "horizontally arranged stone blocks" noted by Lodolo and colleagues, is that these rectangular shaped blocks are the result of post-depositional erosion of the stone, followed by the ridge cracking and settling on its southern sea side. The weathering and collapse of large sections of a beachrock ridge usually occurs due to erosion and scoring of underlying sediments on its sea side, or due to a landside [
76] (
Figure 1 and
Figure 11d). Such beachrock erosion is common in coastal environments, and can be seen for example, on the Israeli Mediterranean Sea coast at Ashkelon (on the seaside of the beachrock outcrop) – [
76] (
Figure 3) or at Akko on the landside of the beachrock outcrop (
Figure 14 and
Figure 15) as well as in other localities e.g., south-east Africa [
77] (
Figure 16).
Lodolo and colleagues suggest that these "block" features may be the result of human modification, although they cite the publication of Shinn [
78] who outlined in some detail the "
simple mechanism that can produce beach-rock geometries” similar to those characteristics observed on the seaward side of Ridge 1, namely "
Exposure to sunlight and constant wetting and drying break the rock down into individual slabs, like to a concrete road.
The size of the individual slabs is determined by the thickness of the rock. Uncemented sand under the rock also promotes cracking as the rock settles, much like ice on a frozen pond." Shinn [
78] gives an entirely plausible, natural explanation for the shape as well as the location of stone blocks similar to those observed on the Pantaleria Vecchia Bank.
Likewise, the possibility of modification of Ridge 2 by people some 9500 BP, i.e. the building of a wall-like structure with stone blocks as proposed by Lodolo and Ben Avraham [
58], is not supported by any archaeological or geoarchaeological information presented by the authors. A more parsimonious explanation is that Ridge 2 was deposited at an earlier stage, under different environmental and sea conditions prevailing during the deposition of Ridge 1, creating a different paleo-coastline. Thus, Ridge 2 may represent a natural relic of one of the half-ring ridges, rather than being a human-made feature.
Regarding the so-called Monolith, Lodolo and Ben-Avraham [
59] state that “the monolith is made from stone other than those which constitute all the neighboring outcrops …”, but they also state that “the lithology and age of the rock that makes up the monolith are similar to those that make up the blocks of the rectilinear ridge closing the embayment.” Thus, the Monolith probably originated from the neighboring eroded beachrock Ridge 1 which is located some 300m to the south. It is feasible that when the bay was flooded some 9500-9200 years BP [
59] (
Figure 8), a large, elongated piece of rock broke off Ridge 1 and was washed inland (northward) by a tsunami or by storm waves and was later broken up into three separate blocks by erosion.
As to the possibility that the half-ring ridges are anthropogenic in origin, as in the case of the other features discussed above, this statement is not supported by any archaeological or geoarchaeological information presented by the authors.
Lodolo and Ben-Avraham [
59] state that “the monolith has three regular holes of similar diameter, one that crosses it completely on its top, and another two at two sides of the monolith”. We reiterate here the counter arguments first raised by Tusa et al. [
69] concerning the holes in the rocks, since these appear to have gone unnoticed in the literature or by Lodolo and colleagues in their 2015 and subsequent papers. Tusa et al. rightly contended that these are typical products of coastal erosion of beachrock, either by plant or else by water action when the rock was exposed in the highly energetic palaeo-intertidal zone.
Careful observations of
Figure 4 in the Lodolo and Ben-Avraham 2015 article [
59] depicting the stones, indicates that the holes are of different size and are not regular in shape. Indeed, they appear to be natural in origin; one is a through perforation and two appear to be cavities. In the intertidal and supratidal zones, a variety of process can cause erosion of rock, such as physical or chemical erosion, bio-erosion, and algal induration [
76,
77,
79]. Round holes, cavities, geyser chimneys (
Figure 17) and craters are scoured and abraded by water under the influence of currents waves and are typical of high energy, intertidal, rocky environments. In their rebuttal, Tusa et al. [
69] also note that even perfectly cylindrical holes can be created by natural action. They further suggest that natural erosion, due to plant action, can create similar holes:
"over 5 m long and with a section compatible with those shown in Lodolo and Ben-Avraham [59], and are found in large numbers along the coasts of the Black Sea, on lithologies similar to that of the "monolith" [e.g., Erginal et al. 80]".
Lodolo and colleagues present the dating of the stones composing the Monolith and the Ridges (SI
Table S1). The dates represent the period of deposition and consolidation of the bioclastic rocks, and so are not pertinent to the issue of whether these features are anthropogenic in origin or natural.
The proposed dating of the Monolith, which according to Lodolo and Ben-Avraham [
59] implies an anthropogenic origin, and the possible modification of the two beachrock/consolidated beach deposits ridges by humans [
58] is based by them purely on sea-level considerations and speculations. The sea-level curves cited [
71,
81,
82] suggest that some 9200-9500 YBP, the sea level in the Sicilian Channel was ca. 40 m lower than today (
Figure 13) and the Pantelleria Vecchia Bank was a small island between Pantelleria and the Sicilian coast. Thus, the ridges and Monolith were under coastal/shallow marine conditions at the beginning of the Holocene. Lodolo and colleagues note that this palaeo-coastal area would have been accessible to humans during certain prehistoric periods. However, this situation is also valid for thousands of other square kilometers of continental shelves around the globe, down to a depth of 40 m. Consequently, basing human intervention on a speculative argument of possible accessibility to the area where the ridges and monolith were found, cannot be considered as scientific proof to support a Mesolithic anthropogenic origin for the monolith stone feature - as suggested by Lodolo and Ben-Avraham [
59], nor for the modification of the ridges during the early Neolithic -as proposed by Lodolo et al. [
58].
In their discussion of the rock formations of Pantelleria, Tusa et al. [
69] detail why, on archaeological grounds, the presence of a monolith, that can be compared or traced to the central Mediterranean megalithic tradition in these locations, is not feasible. In addition, they also refute the proposed dating suggested by Lodolo and colleagues for Pantelleria Vecchia Bank. It should be noted here, that Lodolo and colleagues did not involve a professional archaeologist, who may have related to the existence or nonexistence of anthropogenic fingerprints and finds of material culture.
In general, the possibility of finding unique stone structures in archaeological sites, cannot be ruled out. However, usually the raw materials used in their construction, or manner in which they were built, have parallels in other contemporaneous sites in the same region. In the case of the Pantelleria Vecchia Bank features, we do not know of any contemporaneous (i.e. Mesolithic), terrestrial parallels in Italy for structures made with the same raw materials, with similar-sized large blocks, or that resemble the form of the submerged features documented by Lodolo and colleagues. It is also unlikely that such a monumental ancient structure would have been built on a remote, offshore island, with no developed cultural center that could have supported such a project, leaving no anthropogenic fingerprints. Tusa et al. [
69] refute the comparisons made by Lodolo and Ben Avraham [
59] to the monolithic cultures of Malta and Gobekli Tepe in Turkey, which are both chronologically and culturally distant from Sicily. As Tusa et al. conclude:
"…it is absolutely methodologically incorrect to compare distant and independent historical dynamics to justify the alleged presence of absolutely unjustifiable artifacts in their correct geographical reference context."
It is expected that a prehistoric culture capable of producing gigantic megaliths and mega-constructions, would leave behind at least a few anthropogenic finds of distinctive material culture (e.g., flint implements, bones, wood, charcoal, ash). The absence of such finds is perhaps the strongest argument against the Ridges and Monolith being anthropogenic in nature. For example, stone tools, faunal remains, and even a hearth feature were discovered adjacent to a Neolithic seawall made of large boulders off the Israeli coast, corroborating that this structure was definitely human-made [
19]. At the very least, flint artifacts that are highly resistant to erosion even in underwater conditions (as attested to at hundreds of submerged prehistoric sites discovered worldwide) e.g., [
4,
5,
83], are expected to have been preserved and discovered in association with at least one of the features described at the Pantelleria Vecchia Bank. The feasibility of this is highlighted by the presence of human-made artifacts recovered underwater near the Pantelleria Island [
84].
4.2. The Lampedusa Site
Megalithic constructions are not uncommon in the European Bronze Age. In fact, such structures can be found in the Central Mediterranean islands, Malta and Sicily, with some smaller ones reported also on the Central and Eastern parts of Lampedusa Island [
62,
68]. This cultural connection has deep roots, as the two groups of islands shared cultural traces since the Neolithic (~5500BC) when the first attested colonists from Sicily established themselves in Malta [
85]. The two groups kept cultural ties alive for millennia as shown by parallels in their pottery traditions, flint, obsidian and ocher trades, as well as cultural and religious practices [see 86–88]. While these early cultural trends seem to have originated on the main island of Sicily and were introduced to Malta, scholars propose that the opposite is true for the Early Bronze Age megalithic traditions [
89,
90,
91]. Megalithic building seems to have started in Malta ~3500BC and was connected, to new ritual practices including group burials. Only later was it brought to Sicily see [
91]. Similar group burial practices are suggested in Sicily for the dolmen structures appearing in the third millennium in the Hyblean Plateau and in other scattered sites north and southwest of the main island of Sicily see [
91,
92]. In his 2014 publication, Ratti [
64] (p. 18) pointed out an oval stone structure located in Lampedusa on the top of the cliff above the suspected submerged cultic site, which has never been excavated nor published (our translation from Italian) “
A stone structure of the same shape and dimensions of the underwater one can be seen on top of the cliff (110 m above sea level) exactly above the submerged one”. This structure is also depicted in his 2022 edition [
68] (
Figure 2.85). During a field survey we conducted on the top of the cliff, some stone arrangement and structures were identified. However, unlike the boulders found in the suspected submerged megalithic structure (the latter weighing up to a few tons each), the terrestrial structure is built of smaller stones arranged in patterns that differ markedly from the underwater feature. Thus, the yet unexcavated and undated stone structures on top of the cliff, and the other megalithic structures on the island do not represent possible parallels to the suspected submerged structures.
To estimate changes in the local relative sea-level and possible tectonic uplift of Lampedusa, two sets of sea-level indicators were investigated. Marine Isotope Stage 5e (MIS5e) beach deposits dated to the last interglacial high stand (124 ka) were identified based on fossil indicators (e.g. mollusk species:
Strobilus boboniou, Patella fereginous and
Arca noa)
1. The find elevations of these mollusks relative to modern sea level was documented for the methodology and examples see [
56,
93,
94,
95,
96,
97,
98]. This parameter was of use to our understanding of the relative sea level during the Mid-Pleistocene when the global sea level was ca. 6 to 12m higher than today, and facilitated evaluation of the long-term vertical changes of the island since the deposition of these beach deposits. The heights of coastal installations (e.g. rock-cut bollards to which boats were tied) relative to sea-level today, provided sea-level information during historical periods. These Upper Pleistocene and Late Holocene geological and archaeological indicators (respectively) enable evaluation of the relative sea-level height and tectonic stability of the region during prehistoric and historic times.
Previously, Segre [
99] and Grasso and Pedly [
66] located Tyrrhenian terraces and MIS5e deposits while producing the geological map of Lampedusa. East of the monocline, on the ria-coastline (from Cala Greca to Cala Creta see
Figure 2), Tyrrhenian features consisting of beach deposits containing the mollusk
Strombus bubonius, lie at ca.+2m above present sea level [
99] (p. 138). West of the monocline, prehistoric caves were identified by Segre [
99] (pp. 145-147,
Figure 7: d) at elevation of ca 35m above sea level. Grasso and Pedly [
66] suggested that these caves are related to the same Tyrrhenian episode identified on the east side of the island, and that the tectonic movement associated with the monoclinal flexure was completed by Late Pleistocene times.
Following these studies, we rechecked the deposits in some key sites on the island of Lampedusa. In Cala Ucello Bay, a clear MIS5e beach deposit with at least four individuals of the index fossil
Strombus bubonius in a good state of preservation, were identified (
Figure 18). The maximum elevation (inner edge) of this deposit was 2.20m asl (at 6.30 pm on 3 August 2019). In Cala Maluk, a MIS5e beach deposit formation was identified on the western side of the bay. In this case, other index fossils,
Patella ferruginous and
Arca noa mollusks, were observed. The maximum elevation of the deposit was 1.60 m asl (at 7.00 pm). Another MIS5e deposit at a similar elevation containing
Strombus bubonious was identified in Cala Pisana. Overall, all the MIS5e/Tyrrhenian deposits studied do not display evidence of dramatic tectonic changes in the region during the time period of the formation of the coastal escarpment. According to Lambeck et al. [
100] (
Figure 6), the average rates of vertical movements in the Linosa/Pantaleria region during the Holocene, and for the last glacial cycle, has been ±0.15 mm/yr. Assuming that tectonic movement associated with the monoclinal flexure on the island was completed by Late Pleistocene time as suggested by [
66], tectonics would have had very little impact on the significant erosion of the cliff above the suspected cultic site, which presumably started at the Mid-Holocene, when sea-level reached its present elevation.
These were identified in Cala Pisana Bay where a modern beachrock formation, composed of modern materials (e.g., glass, and metal), was located on the shoreline at an elevation associated with the present sea level. Important archaeological indicators identified were rock-cut bollards that are reported here for the first time (
Figure 19). Of the 16 bollards located, two were in Cala Pisana Bay, and the rest were in the Porto Vecchio (Cala Palme), and Porto Nuovo (Cala Salina). Other rock-cut features such as carved channels and square installations were also identified in the harbor area, and a large quarry site, a few meters above current sea level, was observed in Cala Calandro. Although such rock-cut bollards are hard to date, and some of them are still being used (e.g., in Brucoli Sicily, lat. 37.2817 N, lon. 15.1862 E), similar installations found in well-documented archaeological sites [
101,
102] suggest that they date to the Roman-Byzantine periods. Some of those rock-cut installations were affected by sea erosion and modern coastal constructions, however, their elevation about sea level enables proper functioning, suggesting that the relative sea level has not changed dramatically in the last 2000 years, since they were cut in the stone.
In-situ submerged prehistoric sites can be found on submerged landscapes inundated by post-glacial sea-level rise. However, some submerged landscapes are relatively new (post-prehistoric periods, hence submerged neo-landscape). Examples for such submerged neo-landscape may be at the foot of an active, retreating coastal escarpment (
Figure 20 and
Figure 21), or on the surface of a consolidated lava flow which entered the sea. In situ finds discovered on such landscapes, may then be logically be attributed to a period later than the formation of the landscape. Thus, the date of the deposition of the natural rock may be used as a
terminus post quem for the site deposited on it.
The erosion rate of the cliff and the proximity to the cliff were major arguments to rule out the possibility of the suspected Lampedusa site being anthropogenic in origin. An important geological indicator in the study area was a sea stack, probably part of the island in the past which had been separated from the present shoreline (
Figure 7 and
Figure 21). The fresh landslides on the coastal escarpment and its active retreat suggest that the features in the studied site (the coastal cliff and caves, the adjacent sea bottom and the stack) are products of events that have occurred during the second half of the Holocene sea-level rise.