The Ancient Morphology of the Po Plain in the Area of Bologna (Italy)
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Grog/". fh. DÙlam. QUII/. 23 (2000), 47-58, 10 figg., 1 lab. GABRIELE GIORGI C") THE ANCIENT MORPHOLOGY OF THE PO PLAIN IN THE AREA OF BOLOGNA (ITALY) ABSTRACT: G10RGI G., Tbe Ancient i'vIorpbology 01 the Po Plaill ili the nura appariva molto più regolare rispetto a quanto appaia al giorno d'og ami o/Bologl/a ([tal,,). (IT ISSN 0391·9838, 2000). gi. Ll quota di rinvenimento di l'epeni archeologici non rimaneggiuti, di mostnmo l'asscnza di cvidcnti dossi fluviali. I corsi d'acqua scorrevano in A multidisciplinaty approach has permitted to reconstruct the ancient cisi all'interno dci propri scdimemi, come avviene attualmente nella parte morphology of the Po Plain north of Bologna. Covering an area of about sinistra del bacino del Po. Il modo in cui è organizzata la centuriazione 766 squsre kilomc[rcs, tbe terri10ry is characterized by the presence of a romana conferma detta ipotesi. La centuriazione è un metodo, utilizzato considerable number of fluvial ridgcs. At thc timc of tbe Roman colonisa dai romani per la suddivisione del territorio, che teneva fortemente conto tion in the Il cemury B.e. the plnin \Vas far more even as compared 10 to degli aspetti morfologici, in quanto ad essa erano attribuite anche funzio day. The absence of ridges is bome out by the lnrge number of archaeo ni di drenaggio delle acque superficiali. Essa non avrebbe certamente logica] fiods that have been found in situo Streams flowed carving their svolto la sua funzione se la morfologia fosse stata simile a quclla odierna, sediments, as is still the case along the Ieft side of the Po. Roman centuri a causa dei rilievi e delle depressioni che attualmentc la caratterizzano. La azione patterns confirm this hypothesis. Centuriazione is a land sub sua efficienza era determinata esclusivamente dalla prescoza di una division practice adopted by the Romans which strongly takes imo ac morfologia più omogenea rispetto a quella attuale. count the morphological aspects of a territory as one oE ics functions was L'aggradazione, che ha formato i numerosi dossi, ebbe inizio a parti to facilitate surface \Vater flow-off. If ancient morphology had been ehar re presumibilmeme dal III secolo d.C., continuando per tutto l'alto me acterized by ridges and depressions, as is the casc toda)', this type of sys dio evo. Gli alvei dei corsi d'acqua si sono vClluti perciò a travare a quote tem \Vould have been unsuitabie to ensure drainage. For it to have effec superiori a quelle del piano circostante, sconvolgendo così l'assetto idrau tively performed this essential function the morphology at the time rnust lico della pianura e determinando l'abbandono di grandi porzioni dei ter have becn far more unifonn and homogeneolls than what it currently is. ritOl'i da parte dell'uomo. The process of aggradation, which has given rise to the formation of tbc numeraus ridges found toda)', presumably began in the third century TERMINI CIIIAVE: Archeologia, Evoluzione tardo Quaternaria, Mo delli digitali altimetrici, Pianura Padana, Pianura di Bologna. A.D. aod continued throughollt the Middle Ages. The riverbeds tbus came to find themselves above the lcvel of the surrounding plain so tbat the hydraulic sel up \Vas upset anel large portions of the territory \Vere ]ost comrolof. INTRODUCTION KEY WORDS; Fluvial Plain, Archacology, Late Quaternary evolution, DigitaI Elevatioo Moelel, Po Plain, Bologna area (Italy). An exhaustive clescription of the main morphological features typical of plain lanclscapes can be found in two re RIASSUNTO: GIORGl G., La mOll%gia della Pianura Padana, settore cem publications (M,U,RST., 1997a; Castigliani, 1999). bolognese, in epoca storica. (IT ISSN 0391-9838, 2000). These characteristics fall uncler three main categories: L'uso di approcci multidisciplinari ha permesso di ricostruire l'amica those of piedmont and transitional regions; coastline ones; morEologia della pianura padana a nord di Bologna. L'area studiata è di and those typica! of flood plains. 1 circa 766 km , cd è caratterizzata dalla presenza di numerosi dossi fluviali. Flood plain features clepend on the action of strearns, Nel II secolo a.c., durame il periodo della colonizzazione romana, la pia· and riverbecls either sunk beneath or flowing abovc thc gencrallcvel of thc surrounding plain. On thc Ieft side of thc River Po, for instance, tributarics, such as thc Mincio, Oglio, Adda, and Ticino, are generally imbedded, while on ('.,) Dipartimento di Scienze della Terra e Geologico-Ambientali. the righr side they are pensile. Università degli Studi di B%glltl, lta~v. The sloping flanks (0.2-0.4 %) of the fluvial ridges The present .'itud)' has been made po.uible tbauks to fUl1ding !rom tbe make it vcry difficult to visually determine whether or not Minlstn'/or tbe Universit)', Researcb (lud Tec/molog)' (M.U.R.5.TJ IInder the becls are actually pensile. Differences in altitude can tbe «N~tiona/ Rese(ll'cb Project: the allswcr 01 Geomol'pbic Processes to En vimnmmta/ \fariations» 01 whicb Pro! Augusto Bia}lcotti is the /1atioual only be properly gauged rhrough a micromarphological co-ordil/ator. ana!ysis af comaur lines (Giorgi, 1990). 47 Given thm the ridges in the area under study are of re tlers in 189 B.C.. A network of co-orclinates are traced aut l'em formation, the scope of the present paper is to show on the ground (Chevallier, 1960) starting from t\Vo main that at least two thousand years ago the Iandscape in this axes set at righe anglcs to each other cal1ed the decumanus area \Vas similar in appeararree to that cunently extanr maxùnm and tbc all'do maxùnus. The plots \Vere then ob norrh of the Po and that the streams running through ir tained by drawirrg lirres paralleI to these axes evel'Y 20 ac were then imbedded in the sunounding alluvial plain. tus (about 710 metres). These partitions are still partly visi 1vloreover the burial of Roman artefaets and srrucrures un ble taday and are made especially evidcnr by the routes of del' several metres of sedimentary deposits is aseribable to country byways and by path\Vays and lanes separatÌng one the fOfmation of fluvial ridges. fieId from thc otber. Most of the plain surrounding the city of Bologna falls Two areas orr the fringes of the territory under srudy, within the territory examined. lt eovers an area of 766 orre around S. Agata Bolognese the other near Granarolo square kilometres Ioeated more or less between the eourse dell'Emilia and Budrio, stili perfecrly preserve this pattern. of the Panaro River to the WesI and that of the Idiee River Elsewhere fainr traces can stili be gleaned or have utterly to the East (fig. 1). Human settlement in the area dates disappeared, such as in proximity to the River Reno and baek about 3,500 years to the Brame Age, but a more spo the Samoggia Stream. The centuriazione over most of the radic presenee before then cannot be ruled out (Forre, territory dealt with in the study was cemrcd on Bononia, 1991; Minozzi Marzocchi, 1991; Bottazzi, 1991). while a gl'id East of the Idice River off-set clock\Vise by As the study eoneerns thc evolution of a conrinenral ar several degrees '.vith rcspcct to thc former \Vas part of the ea over two to three thousand years dating was pcrformed territory of Claterna, which corrcsponds to the moclern only for indisputable in situ findings and on the basis of day district of Maggio in the municipal territory of Ozzano pedologieaI evidence. Detailed altimetrie assays were made dell'Emilia. by digitalizing poinrs quoted on a map with a scale of Forty-six in situ finds have been taken inro considera 1:5,000 and subsequently processing the data by means of cion (Minozzi Marzocchi, 1991; Scarani, 1968; Silvestri & appropriate cartographie software. Piletti, 1982). Some cf these are connected with gravesites, others reIate to dwelIings, ancl several are objects of every day use (table 1). Thirty-one belong to Ancienr Roman ARCHAEOLOGlCAL FINDS times, eight co the Iran Age, and eighe to the Bronze Age. Site 37 has yiclded severaI finds that were made during a The Roman centuriazione of the territory under study is digging campaign conducted within the boundaries of the of great historical importance and remarkabie visual im centuriazione gl'id. The materiaI belongs not onIy to the pact (fig. 2). It is essentially the gl'id used by the Romans to Roman period but also to that of Celtic occupation and to recIaim and mark aut inro plots the land assigned to set- the Iron and Bronze Ages, thus witnessing [o the Iong- .&. , Cento JllIlJ 1t!!r (.dii> San Pietro Crevalcore /-~ llill .' Pieve di Cento in COlale .&. illll 1ìitr COltello D'Argile Sont'Agata Bolognese 1ifìr , '-, rmt San Giorgio ib..~~=~"""", ~ 11lfc ! San Giovanni i di Piano in Persiceto li / Castel Maggiore / Jl Granaroio dell'Emilla 1l Budrio BOLOGNA FIG. 1 . Area of study (Nonhern ltalyL 48 FIG. 2 Location of fjnd-spots and of tbe Roman centuriazione. r !l:lI39 2 30 ~ Superficial finds Buried finds Centuriazione SOOOm F'jìiIf\Iip standing and continuous presence of human settlement at incision observable in the southeastern corner is ascribable the site. Three specimens, Nos. 39,43, and 44, derive from to the erosion caused by the Idice Stream flowing in its outside the area under study. They have nevertheless been narural bed. The age of these features was determined taken imo consideration so as to gain a better undersrand pardy on the basis of previous srudies (Castalclini & Rai ing of the leve! of Roman remains, as will be explained mondi, 1985; Cimi & Giorgi, 1989; Giorgi, 1998), more thoroughly further on.