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The World of Elephants - International Congress, Rome 2001

1. PALEOGEOGRAPHIC EVOLUTION

The area of the Campagna Romana is extend-ed along the western coast of Central ItalianPeninsula, between the Apennine chain and theTyrrhenian Sea. The Apennine is a complexstructural unit mainly thrusted toward SE andrecently extended in the western sector were,from Tuscan area to Neapolitan region andSouthern Tyrrhenian sea, an alkaline potassicvolcanic back-ark province was developedfrom lower Pleistocene to actual time.

The large and subplanar region of Roma,Latium, shows a landscape mainly linked to the Quaternary tectonic evolution of theTyrrhenian Apennine boundary, with six mainvolcanic districts lying in a extensional plainsurrounded by several Plio-Quaternary marineto continental units. A peculiar Holocene geo-morphological unit of the Tevere river crossesthe Latian region and characterize the coastalarea with a deltaic area, which had an importantrole in the history of Roma.

The specific deep structure of the CampagnaRomana is made by a main extensional struc-ture, mainly founded on previous NW-SEthrust marine Meso-Cenozoic units with basinto shelf carbonate meso-cenozoic facies.

The graben-like structure is filled by Plio-Pleistocene marine deposits, continental Upper

Pleistocene sediments and Sabatini Mts andAlban Hills volcanic products. The sedimenta-ry sequence, from the bottom to the top, iscomposed by a thetysian “ligure” basal unitorganized in a sequence of ramp and flat struc-ture thrusted by a Tuscan basin mesocenozoicstructures, uprising a maximum of few hundredof meters below the surface in correspondencewith structural highs (Cristoforo Colombo,GRA) or in Cesano (1300 m below the surface)in correspondence with a ramp-like structure,filled by an irregular mantle of Plio-Pleistocenemarly clays that represent a sort of imperviouscontinuous cover.

The Plio-Pleistocene marine cover reachesthe boundary of the Apennine chain and out-crops in correspondence of structural highs,previous inheritance of deep ramps still presentat surface level also within the city of Roma(Monte Mario, Monte Ciocci and Monte dellePiche units). A complex pattern of regionalstructural units controls the different outcropsof these sediments, finally influencing the geo-morphological pattern of the area. In figure 1the interaction between the deep gravimetricstructural pattern (Toro 1976) and superficiallandscape is shown. Distribution and activity ofvolcanoes, surface and deep hydrogeology,transmission of seismic energy, landscape geo-morphological evolution, features connected

General geological features of the Campagna Romana

R. Funiciello, M. Parotto

Dipartimento di Scienze Geologiche, Università degli Studi di Roma Tre, Roma, Italy -

funiciel@uniroma3.it, parotto@uniroma3.it

SUMMARY: The paleogeographic evolution of the Campagna Romana is presented as an integrated study ofsubsurface structural features and lithostratigraphy of superficial outcrops within the Roman suburbs. Outcropping units were developed from differentiated environmental conditions, from marine Plio-Pleistocene clayey and sandy deposits to continental Middle to Upper Pleistocene shales and conglomerates.Since the Matuyama-Brunhes magnetic reversal until Holocene, huge volumes of volcanic products wereemitted by two volcanic Districts, located NW (Sabatini Mts) and SE (Alban Hills) of Roma.

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with paleoenvironment evolution are mainlydue to the deep structural pattern. Connectionsamong tectonic activity, climatic and paleogeo-graphic changes related to the glacial and inter-glacial periods produced a complex transgres-sive cycle characterized by the alternation ofdeposition and erosional phases.

After the Matuyama-Brunhes magneticreversal, Sabatini Mts and Alban Hills volcanicdistricts were developed NE and south ofRoma. Regional extensional and transtensionaltectonic produced an intense activity, mainlyexplosive, with a volume of volcanics ranging

between 500 and 1000 km3. These eventsdeeply modified landscapes and environment,hydrology and hydrogeology of the area ofRoma.

A relevant regression of the sea level acceler-ated the erosional processes of the Tevere riverexcavating the Pliocene bedrock more than 60meters below sea level. During the subsequentrise of the sea level, the articulated networkexcavate by the Tevere river and its tributarieswas filled with alluvial Holocene deposits, con-sisting of unconsolidated clayey-sandy sedi-ments.

General geological features of the Campagna Romana

Fig.1 - Landscape of the Campagna Romana, with the main gravimetric features and the Late Bronze Agesites.

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The World of Elephants - International Congress, Rome 2001

Figures 2 and 3 show to the main paleogeo-graphic events of the Campagna Romana andlandscape evolution since Upper Pliocene (thedashed squares in figures indicate the succes-sive steps of the paleogeographic evolution).• 2.1) The sea was reaching the border of theApennine chain; a thick sedimentary clay tomarly clay unit was deposited in a wide areacorresponding to what will become theCampagna Romana. The structural relieves ofSoratte Mt. and Cornicolani Mts were smallislands NW-SE trending; from the futureMonte Mario toward the future Roma down-town area, a shallow marine environment wasdeveloped.• 2.2) The relief of Monte Mario came out from

a wide sedimentary cover of sandy-gravellydeposits which was giving rise to the coastalbelt. The ancient course of the Tevere river hadits mouth to the South of the present position.• 2.3) Extent of Alban Hills and Sabatini Mtsvolcanic products, mainly ignimbrites, andmodification of the drainage pattern of theTevere river.• 2.4) Geomorphological and geological sketchof the Roma area during last low stand of sealevel and deep erosion of the hydrogeologicalnetwork of the Tevere river, confined in thepresent-day river bed. The relics of the volcanicplateau represent the present day eastern topo-graphic relieves of Roma. • 3) The Tevere valley was delimited at the

Fig.2 - Paleogeographic evolution of the Campagna Romana.

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western margin by the Monte-Mario-Gianicoloridge, and, in the eastern portion of the town,by the relics of the volcanic plateau, the famousSeven Hills of Roma. During the Holocenehigh stand of sea level, the recent alluviumfilled the deep valley excavated by the Tevereriver during the Wurmian glacial period. (A=recent alluvial deposits of Tevere river and itstributaries; for other symbols see Fig. 2).

2. HOLOCENE DEPOSITS AND FINAL

CONSIDERATIONS

Three peculiar geological features weredeveloped in the Roma area until Holocene witha rapid continuous evolution: the Acque Albulehydrothermal basin, the Tevere river delta and aflat area northward of the Albano lake (Fig. 1).

These quite contemporaneous features areobviously deeply different in origin as a func-tion of different location and influence on thesurrounding environment. The landscape ofthese features is always flat in a sharp morpho-

logical contrast with the Pleistocene morpholo-gy of surrounding areas of the CampagnaRomana.

The Acque Albule basin is a tectonic depres-sion 30 km2 large where thermomineral springsand travertine depositional processes are stillactive. Radiometric analyses (230Th/234U) indi-cate that the travertine began to deposit around165 ka ago. The uppermost travertine depositso called “cappellaccio” began its depositionearlier than 40 ka ago. Actually the travertine isstill in active deposition by means of huge ther-momineral springs upwelling with a flow ofmore than 4m3/s with an average speed of 0.43mm/a.

The Tevere delta accreted for long time. Theevolutive deltaic cycle began with the lasteustatic sea level rise and the river mouth posi-tion was migrated 10 km westward in the last18 ka. Impressive geomorphological changeswere penecontemporaneous to the protostoricand historic evolution of the area. Lagoonal andsandy islands environments were developed

General geological features of the Campagna Romana

Fig.3 - Present natural landscape of the Roma area.

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The World of Elephants - International Congress, Rome 2001

along the coastline 3000 years ago. Being thesea level quite stable the lagoon was filled withTevere river deposits, consequently the lagoon-delta body rapidly prograded towards the bar.During the imperial times two main lagoonswere isolated from the river. The positions ofthe Claudius and Trajanus harbours and theirartificial canals gave rise the present mouth ofFiumicino. Anywere the Tevere river has builtup its delta in the last 2000 years prograding 6km toward the Tyrrhenian sea.

A third flat Holocene area was created north-ward of Albano lake within the western sectorof the Alban Hills volcanic district. It wasmainly connected with the limnopalustriandeposits produced by the lake positive move-ments and flowing. The possible connectionwith late endogenous activity or climatic crisisis still debated and studied. Development of thearcaic cultures until roman times seems to beinfluenced by this peculiar feature.

The continuous link among deep structuralfeatures, surface distribution of geologicalunits, landscape of the Campagna Romana, dis-tribution of sites of human settlement fromStone Age to historical times and importantQuaternary fossil mammals rich outcropsseems to be clear. It seems to be mainly fol-lowing the influences and restrictions of thecontinuos evolution of the environmental con-dition and also depending from some cata-strophic event connected with volcanic, tecton-ic or hydrometeorological conditions.

3. REFERENCES

Ambrosetti, P & Bonadonna, F.P 1967.Revisione dei dati sul Plio-Pleistocene diRoma. Atti Accademia Gioenia di sc:nat.inCatania 18: 33-70.

Anzidei, A.P., Bietti Sestieri, A.M., Desanctis,

A. 1985. Roma e il Lazio dall’Età dellaPietra alla Formazione della città. InArcheologia e Storia di Roma. Ed. Quasar.

Bellotti, P., Caputo, C., Ciccacci, S., De Rita,D., Donati, S., Fredi, P., Funiciello, R., LaMonica, G.B., Landini, B., Marra, F., Milli,S., Parotto, M., Pugliese, F. 1997.Fundaments for a geomorphologicaloverview on Roma and its surroundings.Suppl Geogr. Fis. e Dinamica Quat., Suppl.III, 2: 105-121.

Di Filippo, Toro, B. 1980. Analisi gravimetricadelle strutture geologiche del Lazio merid-ionale. Geologica Romana 19: 285-294.

Donati, S., Funiciello, R., Rovelli, A. 1998.Seismic response in archeological areas: thecase histories of Rome. Journal of AppliedGeophysics 41: 229-239.

Faccenna, C., Funiciello, R., Montone, P.,Parotto, M., Voltaggio, M. 1994. LatePleistocene strike-slip tectonics in theAcque Albule Basin (Tivoli, Latium).Memorie Descrittive della Carta Geologicad’Italia 49: 37-50.

Funiciello, R., Rovelli, A. 1998. Terremoti eMonumenti in Roma. Le Scienze 357: 42-49

Locardi, E., Lombardi, G., Funiciello, R.,Parotto, M. 1977. The main volcanic groupsof Latium (Italy): relations between struc-tural evolution and petrogenesis. GeologicaRomana 15: 279-300.

Marra, F., Rosa, C., De Rita, D., Funiciello, R.1998. Stratigraphic and tectonic features ofthe middle Pleistocene sedimentary and vol-canic deposits in the area of Rome (Italy).Quaternary International 47/48: 51-63.

Toro, B. 1976. Gravimetry and deep structureof the sabatinian and alban volcanic area(Latium). Geologica Romana 15: 301-310.