Mapping of the Stones in the Main Façade of St. Giuliana Castle (Umbertide, Italy)

giammartini:periodico 30/11/2010 12:42 Pagina 11 Period. Mineral. (2010), Special Issue, 11-20 doi: 10.2451/2010Pm0018 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 , Archeometry and Cultural Heritage Mapping of the stones in the main façade of St. Giuliana castle (Umbertide, Italy) BarBara Giammartini Dipartimento di Scienze della terra, Università di Perugia, Piazza Università, i-06123, Perugia, italy Submitted, September 2010 - Accepted, November 2010 aBStraCt - this article reports the mapping of the mune di Umbertide (n-o Umbria). materials employed in the main façade of the medieval La facciata principale, realizzata con rocce di pro - castle of St. Giuliana (Xiii-XiV century a.D). this is venienza locale, risulta particolarmente interessante one of the best examples of a fortified settlement, per l’abbondante ed esclusiva presenza di conci di tra - located on mt. Corona (708 m a.s.l.) in Umbertide (n- vertino, completamente assente sia nelle murature W Umbria). delle altre unità strutturali del castello sia nelle strut - the main façade, made with stones of local origin, ture murarie degli altri castelli medievali appartenenti is particularly interesting for the extensive and unusual al territorio di Umbertide. presence of travertine ashlars, which are completely il travertino oggi è molto raro nel territorio limi - absent in the walls of the other structural units of this trofo; ne rimangono soltanto piccole tracce sul monte castle and in the construction walls of the other Corona nei pressi di ascagnano. medieval castles belonging to the neighbouring Le altre rocce impiegate sia arenarie (appartenenti territory. alla Formazione marnoso-arenacea Umbra) sia cal - travertine stone, is now almost rare in the cari (appartenenti alle formazioni della Scaglia; mem - surrounding area; there are only small outcrops of it bri della Scaglia Variegata e della Scaglia rossa e alla on mt. Corona near ascagnano. formazione della maiolica), provengono tutte dal the other stones that were used are either monte Corona ad una distanza dal castello non supe - sandstones (belonging to the Umbrian marnoso - riore ai 3 km. arenacea fm) and limestones (belonging to the in opera inoltre, sono presenti laterizi attribuibili ad lithostratigraphic Scaglia Variegata and Scaglia rossa una fase posteriore di restauro. fms, and the maiolica fm) all coming from the southern side of mt. Corona at low distance from the KEy WorDS : lithological mapping; medieval castle (less than 3 km). there are also some bricks buildings; N-W Umbria (Italy). from later building restorations. introDUCtion riaSSUnto - in questo articolo si riporta la mappa - tura dei materiali in opera nella facciata principale del in many monuments different types of stones castello medievale di S.Giuliana (Xiii-XiV sec. d.c) ; are used for architectural designs, construction uno dei migliori esempi di insediamento fortificato lo - and art. they also have been chosen for their calizzato sul monte Corona (708 m s.l.m.), nel co - availability and workability. *Corresponding author, E-mail: [email protected] giammartini:periodico 30/11/2010 12:42 Pagina 12 12 BarBara Giammartini During the restoration work it is foundamental was used to store, process and visualize, using a to identify and to evaluate the degree of vector based graphics, the types of stones on the deterioration of the stones. wall surface of the façade. Currently, computer technology applied to the obtained relief is composed of multiple cultural heritage is a valuable tool to support sets of lines arranged on multiple levels; these conservation and restoration of architectural and have been converted into a set of closed objects, monumental heritage. corresponding to the individual ashlars in the thanks to modern CaD (Computer aided façade. Design) it is possible to map the monument Lithological mapping includes the registration using digitized plans and record the different of all the types of stones and a quantitative lithotypes in place. assessment referred to the number and the Plans and digital information files with surface of the stone. planimetric data, allows multiple options for in the final graphic elaboration an error in questions, pictures, and quantitative assessments representing the ashlars in a range from 0 to max. processing information. 2 cm is expected. this article describes the lithological mapping of the main façade of the castle of St. Giuliana. Sampling it is particularly interesting because it represents the only example of a medieval wall in the Up to 15 samples considered fully representative municipal territory of Umbertide (Giammartini, of the employed natural materials have been 2009) in which were used travertine stone. this collected from the main façade of the previously area has been mapped stone by stone to document cited castle in order to be characterized by the distribution of different lithotypes used. micropaleontological - petrographic methods (a the castle of St. Giuliana is considered a true thin section). pearl of superior beauty; of the 30 medieval castles belonging to the current territory of the iDEntiFiCation oF natUraL StonES municipality of Umbertide, it is particularly interesting and worthy of study for both the state Listed below are the various lithotypes of conservation and its structural typology. Last identified in the main façade of the castle of St. but not least it was chosen by director michele Giuliana. they belong to the Umbria - marche Soavi, in 2002, when he shot some scenes for the stratigraphic succession, outcropping in the film “Francesco” on the life of San Francesco Umbertide area and particularly just to the south d’assisi. (1-2 Km) of the top of mt. Corona (708 m a.s.l.), site of the castle. the lithotypes cropping out in mEthoDS anD SamPLinG the area belong to two different overlying Lithological mapping tectonic units. the Lower Unit (autochthonous) is made by a triassic-Palaeogene sedimentary the mapping of the main façade of the Castle sequence, of Umbrian type, mainly carbonatic, of St. Giuliana was carried out identifying the followed by miocene turbidites. the Upper Unit lithological nature of every single ashlar and (allochthonous) of tuscan type, is composed in every stone fragment, basing on macroscopic the lower part by the “ Argille Varicolori “ (Late features visible to the naked eye and with the Eocene - Early oligocene) and in the upper part help of eye lenses. by the “ Arenarie del Falterona “ (Late oligocene CaD software (autoCaD 2010, autoDesk) - aquitanian p.p.; Boscherini et al .,1981). giammartini:periodico 30/11/2010 12:42 Pagina 13 Mapping of the stones in the main façade of St. Giuliana castle (Umbertide, Italy) 13 the ashlars used to build the main façade are thickness about 100 m. sandstones and limestones and it is documented microfacies: wackestone with benthonic and that these lithotypes were extracted in this area planctonic foraminifers (Fig. 1-C, D; Fig. 2-a). since ancient times. the age of this formation is referable in the For each type of natural stone present in the literature to the turonian p.p. - Early Eocene p.p. façade of the castle the main lithological interval. characteristics and the more frequent associated the main forms of deterioration observed in damages are listed below. this lithotypes are the formation of black crusts; they occur in a fairly compact way forming a Carbonatic rocks dense and highly cohesive film on the wall. there are also biological patinas caused by Maiolica fm - this is a fine white or light gray mosses and lichens activity and fractures on limestone, with conchoidal fracture in regular, some ashlars due to the mechanical action of thin to medium (20-50 cm) strata, containing some plants climbing on the façade. bands and nodules of brown or black chert. also the Scaglia rossa fm outcrops thickness about 130 m. extensively on mt. Corona to the south-east of microfacies: it consists of Calpionellae the castle of St. Giuliana at a distance of less than bearing wackestone - packestone, with radiolaria 1 km. its presence is also documented in the mostly concentrated in the lower part (Fig. 1-a, neighbouring localities of Col Di Lito, Galera B; Fig. 2-E). the age of the formation is referred and Colle San Gianni (a.S.C.U., 1862). it is the to the tithonian p.p. - aptian p.p. interval. most diffused carbonate rock used for the the ashlars show mostly the presence of black construction walls of medieval castles and for patina and some cracks due to the presence of most of the other monumental works in the area. vegetation. Quite large maiolica outcrops occur near the Scaglia Variegata fm - it is a marly limestone rich castle of St. Giuliana, more precisely to the south in planktonic foraminifera, whose colour ranges at a distance of nearly 1 Km. from pinkish gray to light-green. it is generally thin- bedded with strata on average of at least 10 Scaglia Rossa fm - it is pink limestone containing cm, with irregular fracture, alternating with abundant planktonic foraminifera, locally horizons of red clayey marls. the passage to the varying in intensity and turning to white, underlying Scaglia rossa is fairly gradual, alternating with thin-bedded pelitic layers and marked by a progressive reduction in the pelitic bands and nodules of amaranth chert. component an increase in the average thickness the presence of calcite veins, and numerous of the beds and the prevalence convergence of minute granules of metal oxides together with an colours on red tones. abundant foraminiferal microfauna gives it a thickness about 50 m. characteristic pitting. Calcite veins are often microfacies: wackestone with planctonic enriched in iron oxides. foraminifers (Fig. 1-E, F; Fig. 2-D). the age is the Cretaceous part of the formation consists referred to middle and Late Eocene for this almost exclusively of limestones and is formation.

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