The Euganean Trachyte Flagstones ("Basoli") Used by the Romans Along the Mid-Adriatic Coast (Marche, Central Italy): an Archaeometric Study
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Per. Mineral. (2002), 71, SPECIAL ISSUE: Archaeometry and Cultural Heritage, 189-201 http://go.to/permin An International Journal of PERIODICO di MINERALOGIA MINERALOGY, CRYSTALLOGRAPHY, GEOCHEMISTRY, established in 1930 ORE DEPOSITS, PETROLOGY, VOLCANOLOGY and applied topics on Environment, Archaeometry and Cultural Heritage The Euganean trachyte flagstones ("basoli") used by the Romans along the mid-Adriatic coast (Marche, central Italy): an archaeometric study I I 2 3 ALBERTO RENZULU *, PATRIZIA SANTI , GIANCARLO SERRI and MARIO LUNI I Istituto di Vulcanologia e Geochimica, Universita degli Studi di Urbino - Campus Scientifico, localita Crocicchia, 61029 Urbino, Italy. 2 Dipartimento di Scienze della Terra, Universita degli Studi di Parma - Parco Area delle Scienze 157/A, 43100 Parma, Italy. 3 Istituto di Archeologia, Universita degli Studi di Urbino, Via del Balestriere 2, 61029 Urbino, Italy. ABSTRACT. - Trachytes from the Euganean hills RIASSUNTO. - In epoca Romana, nel tratto pili (Veneto) were used by the Romans as flagstones settentrionale della Via Flaminia (tra Fanum (basoli) along the northernmost stretch of the Via Fortunae, i.e. Fano e Ariminum, i.e. Rimini) e in una Flaminia (between Fanum Fortunae, now called pavimentazione nel centro storico di Ancona Fano, and Arimin.um, now Rimini ) and in a (Ancona) sono stati utilizzati basoli trachitici dei pavement of the old town centre of Ancona Colli Euganei (Veneto). Sulla base dei dati raccolti, (Ancona). The latter represents, up to date, the Ancona rappresenta attualmente illimite meridionale southern limit of spread of the Euganean basoli in di diffusione dei basoli euganei in epoca romana. La the Roman period. Source identification of these provenienza di queste rocce vulcaniche e stata volcanic rocks came from mineralogical constraints determinata attraverso vincoli di tipo mineralogico (e.g. presence of anorthoclase), major oxide (e.g. la presenza di anortoclasio) e geochimico (e.g. i geochemistry (e.g., K20/Na20 :::; I), and patterns of rapporti K a20 :::; leI'assenza di anomalie trace elements (e.g., lack of Nb-Ta negative 20/N negative di Nb eTa). Inoltre, la comparazione dei anomaly). In addition, comparison of petrographic parametri petrografici e chimici dei basoli studiati and chemical parameters of these flagstones with con quelli delle trachiti delle cave euganee ha those of the Euganean trachyte quarries permesso di discriminare tre siti estrattivi: discriminated three sites of provenance: Monselice (basoli from Ancona and Via Flaminiai, Mt. Oliveto Monselice (basoli di Ancona e della Via Flaminiai, and Mt. Merlo (basoli from Via Flaminia). These Monte Oliveto e Monte Merlo (basoli della Via three quarries are located in the eastern margin of Flaminiay. Queste tre cave sono localizzate nel the Euganean hills, perfectly located for trading margine orientale dei Colli Euganei, una posizione trachyte blocks along the nearby Adriatic, easily ideale per il commercio dei basoli di trachite achieved by means of the network of drainage attraverso il vicino mare Adriatico, raggiungibile channels and canals (e.g., Fossa Philistina) linked to facilmente con la rete di canali artificiali (e.g. la the rivers Brenta (Meduacus), Bacchiglione fossa Philistinai legata ai fiumi Brenta (Meduacus), (Edrone) and Adige (Atesis). In the Roman period, Bacchiglione (Edrone) e Adige (Atesis). the Atesis ran close to Monselice (before the Quest'ultimo in particolare, che in epoca romana catastrophic flood of 589 A.D.) and the palaeo (prima della catastrofica alluvione del 589 A.D.) Adige was therefore a further waterway linking the attraversava il territorio di Monselice, rappresentava Adriatic coast with the Euganean hills. In order to un'importante via d'acqua che collegava l'Adriatico reach the mid-Adriatic coast, the Romans could also ai Colli Euganei. Per trasportare i basoli verso Ie transport the basoli down to Ravenna along the so destinazioni costiere medio-adriatiche i Romani called Via Endolagunare, an inner waterway running avevano inoltre a disposizione, almeno fino a parallel to the Via Popilia. Ravenna, una via d'acqua endolagunare interna (Via Endolagunare) che correva parallela alIa Via * Corresponding author, E-mail: [email protected] Popilia. 190 A. RENZULLI, P. SANTI, G. SERRI and M. LUNI KEY WORDS: Euganean hills, trachyte, t1agstones, and alteration of this rock and its easy transport basoli, petrology, archaeometry, Romans, along the waterways linked to the Po Plain Marche, Via Flaminia, Ancona. were the main reasons which led the Romans to export trachytes throughout central-northern Italy. Euganean trachyte flagstones have been INTRODUCTION found as far as Bressanone (Brixentes) and Aquileia, respectively north and north-east of The Euganean hills are located in north the Euganean hills; westwards, they are found eastern Italy (Fig. 1) and belong to the Venetian in Pavia (Ticinum; Capedri et al., 2000). Tertiary Volcanic Province (Upper Paleocene Trachyte flagstones from the Euganean hills Upper Oligocene) which developed during the were also used by the Romans to pave the Alpine orogenesis under an extensional regime northernmost stretch of the Via Flaminia along (De Vecchi et al., 1974, 1976; De Pieri et al., the mid-Adriatic coast in central Italy (Fig. 2; 1983; Milani et al., 1999). Recent RblSr Renzulli et al., 1999). The new discovery radiochronological data indicate the Lower (present work) of Euganean trachyte flagstones Oligocene as the most probable time of used to pave a Roman road in the old city eruptions for the Euganean area (Zantedeschi, centre of Ancona (Fig. 3) has shifted the spread 1994). Prevailing rhyolite and trachyte lava of these Venetian lithotypes 50 km southwards. domes with a moderate Na-alkaline magmatic The recent issue of a petrographic and chemical affinity were erupted over an area of about 100 database of the Euganean trachyte quarries km-; latite and basaltic lavas are subordinate (Capedri et al., 2000) was very welcome and (Piccoli et al., 1975). Quarrying in the trachyte greatly stimulated identification of the domes of the Euganean hills was often favoured quarrying sites of the flagstones found in by the fact that the rocks are of columnar Ancona and on the Via Flaminia. On the basis jointed type, making them easier to split of petrographic and geochemical (Capedri et al., 2000). investigations, combined with archaeological The exploitation and trade of Euganean data, we hypothesise here how the Euganean trachyte, documented since palaeo-Venetian trachyte flagstones were moved by the Romans times (VII-VI centuries B.C.; Zantedeschi and from the quarries to the mid-Adriatic coast. Zanco, 1993), became economically important during the Roman period and has continued until the present day, although the ARCHAEOLOGICAL SITES AND SAMPLING environmental impact on the gently sloping hills was devastating. In northern Italy, The trachyte flagstones from Ancona belong Euganean trachytes were mainly used by the to a pavement which dates back to the first Romans for pavements (e.g., Via Aemilia and Roman Imperial Age (Luni, 2000), first Via Popilia, Fig. 2) or bridges (e.g., the Roman discovered in 1987 during restructuring of a bridge in Parma). It was also used as a building building in the old city centre. Sebastiani material (e.g. for columns), funerary (1998) describes this road-stretch as 8 meters monuments, cinerary urns, and cippi long and 5.4 m wide, paved with basoli «of throughout the Po Plain and the Veneto and unknown composition and provenance», Emilia regions (Rodolico, 1964; Negri, 1966; slightly cemented to each other. The pavement Filippi, 1981; Zantedeschi and Zanco, 1993; has a NNW-SSE orientation, a difference of 0.5 De Vecchi and Lazzarini, 1994; Capedri et al., m in level, and is bounded by limestone ramps 2000). Some Euganean trachytes were also on each side (Fig. 3a). The flagstones are used by the Romans to make millstones and irregular in size, being on average 0.6 x 0.4 m, mortars (Santi et al., 2000; Renzulli et al., and ancient tracks of carts can even be detected 2002). The resistance to mechanical abrasion in them. Macroscopically, all the flagstones, The Euganean trachyteflagstones ("basoli") used by the Romans along the mid-Adriatic coast ... 191 I.-_I.-_~---l! N 6Km A M.Merlo M.Rosso M. S. Daniele M. Lispida Monselice Basalts Latites Rhyolites Trachytes Fig. I - General geological map of Euganean hills (after Piccoli et al., 1975). 192 A. RENZULLI, P. SANTI, G. SERRI and M. LUNI Fig. 2 - Viae Publicae in central-northern Italy during Roman period. Location of Euganean hills are also shown (modified after Capedri et al., 2000). characterised by abundant feldspar phenocrysts up to 1 ern in size, have the same yellowish grey colour, and the same porphyritic index and crystal populations (Fig. 3b). The flagstones from the northernmost Fig. 3 - Ancona pavement: a) limestone ramps (right) stretch of the Via Flaminia (Fig. 2) were border pavement consisting of trachyte flagstones; b) close sampled from remains of pavements near the up of trachyte flagstone, showing yellowish-grey groundmass and abundant white feldspar phenocrysts, up Arch of Augustus in Fano (Fanum Fortunae) to I em in size. and between Pesaro (Pisaurwn) and Rimini (Ariminum). The Via Flaminia (Luni, 1995, 2000) was opened around the year 220 B.C. to join Rome to Rimini although, according to the and finally reached Arim.in.um, The Via Itinerarium Antonini (Radke, 1981), the name Flaminia was the most important route used by Flaminia was also used for the road joining the Romans to reach northern Italy and all the Ancona to Brindisium (Brindisi), south along northern provinces of the Roman Empire. In the Adriatic coast. The Via Flaminia stricto the following centuries, the northernmost sensu (Fig. 2) ran along the valley of the Tiber, stretch of the Flaminia continuously ran along crossing the Apennines over the Scheggia Pass. the same route, and the original trachyte It then continued along the valley of the pavement of Augustean age, deeper than the Metauro, reaching the Adriatic at Fanurn present topography, is locally still well Fortunae, then turned north through Pisaurum, preserved.