11 th INTERNA TIONAL BRICKJBLOCK MASONRY CONFERENCE

TONGJI UNIVERSITY, SHANGHAI, CHINA, 14 - 16 OCTOBER 1997

STONY MATERIALS IN THE HISTORICAL BUILDING OF BASILICATA

Nicola Masini

Abstract

Basilicata is a fine example of the difficult meeting between the ancient, which is poor and deep-rooted in time and place, and the modem, which is out of the space-time context. This study on Basilicata's building materiaIs is an indication of the conflict between ancient and modem. Moreover a shallow post-earthquake rebuilding has made the situation worse. This analysis forms part of a research project which intends to fumish the operators interested in Southem ltaly problems, with a guide to traditional building materiaIs and techniques. 1 Moreover it aims to show functions, technological processes of building and places of origin of these local and traditional building materiaIs.

Introduction

The wide range of use of beton brut and steel techniques in the building of this century has had the effect to limit the use of traditional building materiaIs to marginal portions of the architectonic whole. The worldly technologic and cultural process which we have attended, dating above alI from the '20ies, caused a flattening of the local diversities and "vocations" reflected by an unsuccessful relation between the building, the place and the history. The attempts, the experiences and the discussions of who was finding in the "criticaI regionalism" a way out from the spreading "international style" 2 weren't enough. The Catalan regionalismof the '50ies with the Grup R and J.A. Coderch, Alvaro Siza Vieira, the Ticino's villas of Mario Botta, the rural imaginary of the River Po to which Gino Valle draws inspiration, the Greek historicist regionalism, Tadao Ando and the recovery ofthe relation between house and nature in the Japanese culture, are just some

KEYWORDS : MATERIALS, HISTORY, HANDBOOK.

* Researcher ofIstituto Intemazionale di Studi Federiciani (I.I.S.F.) - Consiglio Nazionale delle Ricerche, Area di Ricerca di Potenza, C.da S. Loja - 85050 TITO SCALO (PZ), ITALY.

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examples of a marginal trend in the ccntemporary architectonic culture, that put in a criticaI position towards the dogmas and the "certainties" of the Modem Movement supporters. If we add to this the few space that the study of the traditional building materiaIs and techniques has in the research programs and in the courses of graduation of the faculties of engineering and architecture, it's possible to beco me aware of the wide difference that exists between facts and good proposals, that sometimes end in academic rhetoric, when one meets with the questions related to preservation of the historical cities and of the monuments, and to difficult cohabitation between new settlements and environmentalllnd anthropical pre-existences. In this direction the recovery of the autochthonal cultural values does not imply an autarchic shutting to externaI cultural activities but a criticaI reflection about the tendencies humbling the relation between architecture and the wellbeing ofpeople. The regional building materiaIs and techniques culture is not an immutable status to be studied or preserved as a "good in extinction". It is rather a reality to be cultivated in an aware manner that must constitute a valid methodological and scientific support to a building project, to which today isn't asked only the satisfaction of those basic'physical­technical and ergonomic-functionalduties, but also a correct relation between landscape and settlement, in which the second one could itself become a qualifying element of the first. Basilicata is an excellentobservatory on a difficult cohabitation between the "ancient", poor but rooted in time and place, and the "new" , most of the cases anonymous and tom off completely from space-and-time context. The study of the building materiaIs of Basilicata, under this aspect, is a meaningful sign of this conflict in action. To this are to be added the fateful consequences of an after - 1980's earthquake reconstruction under the signs ofthe emergency and ofthe approximation. The present essay falls within the ambit ofthe research about techniques and materiaIs of the Basilicata building tradition and particularly refers to the tentative to catalogue natural and artificial _stony building materiaIs with relation to their field of use, their areas of diffusion, their working instructions and sites' environmental resources and features (Figs 1-2).3

Basilicata's subsoil offers a remarkable quantity of rocks that or are used, after the working, as cut stones and ornamental stones, or, after the crushing, as broken stones, road making aggregates and alloying elements. In these notes it will follow a short description of the rocks that offer building material, referring particularly to their places of origin and to the territorial areas in which they are used. For this purpose we have done a classification based on geologicand litho-mineralogical cri teria that seemed to us the most complete and objective to catalogue systematically the stone materiaIs, especially if compared to othel' forms of academical classification, based on the instructions about the working and on the fields of use (stones, marbles, etc.), that still we can find in certain technical manuaIs of eighteenth or nineteenth-century inspiration. If we consider, then, the prevalence of some litho-geologic formations in vast areas of Basilicata, as the Vulture's volcanic tuffs4

, the limestones in Matera's province and the metamorphic stones in Lagonegro's 5; such classification allows to have a geographic­territorial global vision on the use of building materiaIs in relation to the resources of the subsoil.

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a. Igneous, or eruptive rocks find their genesis in the consolidation process of vo1canic magma under different conditions of pressure and temperature and they divide in intrusive and effusive rocks. The intrusive rocks derive from the solidification of the magma within the earth's crust and, due to slow cooling and to the action of volatile substances, they are made up as a granular crystalline structure. The effusive rocks instead, derive from cooling of the magma outside ofthe earth surface, in normal conditions oftemperature and pressure. If in Basilicata the outcrops of intrusive rocks aren't remarkable, effusive rocks, instead, don't lack, being present in a vast territory inc1uding Vulture's whole complex, of vo1canic origin, with its ample slopes. The instructions about the working and the use of such rocks depend on their chemical-physical and petrographic characteristics, that vary from zone to zone. . They go from the tuji (tuffs)abundantly used in the buildings of the past, to the lave (lavas) that constitute a good material to realize road pavings. The tuji find ample use: as scabbled stones in supporting and stone masonry, as squared stones in the hip rafters and in the portal frames of the aristocratic buildings and, sometimes, in moulded forms, in ornamental and building elements (window-stills, bricks, mouldings, capitais, etc.). In Melfi the tuff has been particularly used, starting from Middle Age, both in masonry structures and in plastic e1ements of the outfit. Only in the most important buildings, as for example in the cathedral, in the Norman bell-tower and in the castle, the vo1canic material altemates with or has been complete1y supplanted by limestones coming from the environs or from the Apulia. In this century the tuff has fallen out of use after the disastrous earthquake of 1930 that made necessary the use of new technologies and new materiais, as reinforced concrete, to build antiseismic buildings. Melfi had a disorderly town-planning history: anonymous modem quarters without any relation to the historical city, abandonrnent and decay of the medieval village and of the sal)1e antiseismic little houses and, in the centre of the town, introduction of modem buildings neatly opposing the rich building tradition. Ended already and from a long time the "tuff civilization", remain used in these last decades the lave that outcrop from the hills of the Vulture, whose use depends on the petrographic characteristics. From the lava of''joiditico'' character of the mount Vulture, from which road metal for wasp's nests, lean concretes, etc., are only obtainable, to the hauynojiro that constitutes most of the territory and city subsoil of Melfi, which requisites of resistance make fit to several uses, between which the city roads pavings. Unfortunately, the discontinuous extraction in the few still open quarries, the difficult communications with the near regions and the decreasing of the demand inside of the same region, have cut the lava of the Vulture off from the market, to the advantage of other materiais as porphyry originating from Alto Adige and from Campania. Analogous are the problems telating to the pozzolana that is extracted from the vo1canic hinterland, concemed with pyroclastic deposits. Basilicata's pozzolana, utilizable in hydraulic mortars and concretes, if presents some satisfactory mechanical characteristics, cannot adequately be proposed even on the local market ambit.

b. The §edim~ntary rocks, coming from deposits made compact under large pressure, are of limestone or sandstone type. Between these a particular treatment have merited the tuffs of Matera's province, usually c1assified in the Murge Limestones (calcarenitiY that, as the Gargano tuffs and the Lecce stones, are part of the Apulia's calcareniti: The Murge calcareniti are some sedimentations, occurred in sea and contincnt environrnent in the middle superior Pliocene, in an ample territory that goes from the hilly zone south

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and south-west of the province of Bari until beyond the limits between it and the Basilicata. In Matera's environs one can find two different lithotypes: the mount Castig/ione's ca/careniti, whose excellent mechanical properties make them similar to Apulia's carpari and mazzari, and the ca/careniti of Gravina, less compact as composed of a medium-coarse grain. d

The porouser tuff is almo~t always used to realize cut stones, squared or rolled, that constitute the building apparatus of the vertical structures and of the vaults. The most compact ca/careniti consent to be moulded to realize cornices of windows and balconies, bricks, brackets, mouldings and ornamental sculptural reliefs, even if we find them in the vaults and in the masonries. The typologies ofthe tuffbuildings ofthe Sassi9 ofMatera are two: a) masonry in hol/ow pieces, filled with lime mortar, tuff chips and other things; b) monolithic masonry, that is, with full core. The a) type of building apparatus is more frequent, particularly in the bearing walls, while the b) type is findable in the longitudinal masonry's bay of walls and in the carried walls. In both cases the squared cut stones are placed in regular rows. The texture is characterized by the joggling ofthe vertical wall joints and by the alternation of the stony elements put "Iongways" and "head on" which, in the a) case, realize a valid transversal joint between the two building faces, giving the tuff building apparatus an almost memolithic behaviour and making it more fit to bear the stresses due to bending and pressure stresses. Today's use of the tuff in Matera is not only a way of working in its territory without an interruption to its history, but it's also the expression of an increased awareness of the value of the material element in the perception of the place in ali its aspects, from the architectural to the environrnental. What is "excavated" and what is "built" have a connection of aesthetic and functionai symbiosis, in which one establishes the building premi se of the other. The "counter­ground" structure composed by the two externai walls and by pavilion roofs and/or barrel-vaults, recalls the hypogean environrnent of the "grotto" in its architectural meanings and in its social and functional implications. The complex and variegated organization of the architectural spaces, one of the reasons of the charm kindled by the Sassi, is due to the strict connection occurring between the settlement and the proper morphology ofthe place. Then it is a velleity, for an architectural town-planning study of the Sassi, a methodologicalapproach based on the sometimes dogmatic abstractness of the "typologies". But tuff isn't the unique example of Basilicata sedimentary rock from which we get stony elements for masonry work building. Limestones and sandstones outcrop from the wildf1ysch that characterize the geology of vast zones of the province of Potenza, from Campomaggiore to A vigliano, from Castelmezzano to Rionero, from Yaglio to Venosa. I o To these must be added the calcareous formations, present in many hilly slopes of the Appennino Lucano (as the mounts Vo/turino and Pierfaone, between Abriola and Marsicovetere, and the mountA/pi, in Lagonegro's territory) and in the Basento and Agri river basins, furnishing rich lime of good quality. It is not worth mentioning here, due to their vast diffusion in several zones of Basilicata, the river-stones, of various provenance and kind, above ali used as building material in Potenza's province and in those centres that are near rivers anà torrents. The use of the pebbly river-bed stones, in some zones of Basilicata, as in Agri and Camastra valleys, in some centres of the high Basento valley and of the north-eastern zone of the province of

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Potenza, dates back to the high Middle Ages and has been preserved until the XXth century beginnings. The stony material was used in externai pavings of no importance and in the building masonry's apparatus and it was more or less accurately selected according to what had to be realized, an externai and/or internai lateral surface or simply the filling of the opus coementicium. The cobble-stones, then, were in some cases worked and broken. After the "splitting", both the parts were used on the wall surface, with their levei faces turned outward. Between the masonry opus that we know, this, in river­stones, is the poorest and it is typical of a society which economical structure, closed inside itself, is principally based on agriculture and sheep-rearing more than on handicraft. Terracotta and ceramics tradition is also flourishing above ali in those zones, and there's plenty of them, characterized by an abundant quantity of clay in the hilly slope-subsoil. In Calvello, Arrnento, Potenza, Rivello, Viggianello,Policoro, Grottole, Rionero, Melfi, Matera, the ceramic activity in the past has held a very important function in their economical and social growth. From mixed and patterned clay were shaped building elements as bricks for masonry apparatus, vaults and floorings, flat roof tiles, building internai canalisations and household or decorative goods, enamelled or not. In some internai areas of Basilicata, is also particularly interesting the use of hollow cylindrical elements ofterracotta to build light cross vaults and barrei vaults 1 1 (Figs 3-4). Clay was also used in the realization of masonry works. The mixingforrned by fine and coarse aggregates and clay, in variable ratio between them, from 1/4 to 1/6, was put into some wood forrns and then made compact, layer after layer, by mallets ending with wedge-shaped elements. A variation to this technique is the graticcio (rush matting masonry), which origins trace back to the roman opus craticium.12 The building system, used in the realization of partition and bearing wal!s, consisted of a wood frame completely filled with stones of little dimension mixed with clay. Substances of vegetable origin, as straw or minced dry grass, were used to improve the quality of toa fat clays and make the mixing well stuck together. Such building typology of great utility and economy has been vastly used in the Middle Ages, but also in the succeeding ages. To witness for its use in Basilicata there are two documents, one dated 1300 and the other 1306, concerning bills of sales occurred in Potenza, in which appears the term graticia communi that meant one of the boundaries of the purchased domus. 13

c. The metamorphic stones, as marbles and quartzites, are less present than the sedimentary rocks in the subsoil of Basilicata and are used as freestones and crnamental stones, above all. Between these, for their excellent aesthetic value, the Balvano's alabaster, the Castelsaraceno's marble and the Latronico's alabaster signalize themselves. But the first one is cold dependent and in general shows a weak holding of the state of the atmosphere that makes its use only advisable in lining works; the second doesn't outcrop in quantity such to justify its continuai quarrying. The last one, the most precious and known of them, is findable in one of the mount Alpi slopes, in South­Basilicata, at a variable between - 1250 and 1850 Mts. altitude. This rock has very good hardness and workability characteristics. It usually shows some blue-grey or dark-grey veinings on white ground that give valuable decorative effects to the marble. Unfortunately, notwithstanding its excellentphysical-mechanical and aesthetic qualities, mount Alpi's marble hasn't found commercial opportunities, for its remarkable quarrying costs, deriving from the particular vertical stratification of its metamorphic banks under calcareous layers, and from the prohibitive collocation of the quarries into the actual road network. Another time, then, are still the market laws that discourage the use of the internai resources, furnished with remarkable potentialities, to the advantages of others,

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much more in competltlOn than them, above ali for what concems the costs and the available offer. About the analysis ofthe primary causes determiningconditions negative to the exploiting of the mining resources "of value" of Basilicata, I refer to next others studies.

I With regard to this rcearch see Masini , N., Materiali lapidei nell'edilizia storica in Basilicata. , in AA.VV., " Recupero degli edifici antichi. Manualistica e nuove tecnologie. in Atti dei Convegno Intemazionale, Napoli, 29-30 ottobre 1993, Napoli 1995, vol. I, pp. 247-253; Guida A., For cataloguing and studying the abacus of the historical building materiais used in civil building industry, in Acts of 10th IB2Mac, Calgary (Canada), July 5-7 1994, 1995. 2 Frampton K., Storia dell'architettura moderna, Bologna 1986, pp. 371-387. 3 With researcher Antonella Guida of Faculty of Engineering of Potenza I set some forms to catalogue and study the abacus of the historical building materiais of Basilicata. 4 Mount of volcanic origin located in the north of Basilicata. 5 Lagonegro is a little town in the south of Basilicata. 6 Murge is territory in the region of Apulia, located to East 01' Basilicata. 7 Stella M., Le pietre da costruzione di Puglia : il tufo calcareo e la pietra leccese, Bari 1992, pp. 40-41; Setta M. - Marrone P. , Murature esterne in tufo calcarenitico pugliese : caratteristiche tecnologiche e prestazionali per la verifica della affidabilità, Bari 1993, p.26.

8 The limestones of Apulia are usually classitied, on the ground of their physical- mechanical characteristics, by a terminology that refers to their shapes and to the degree of solidity and workability. Some of the most known denominations are the following: Mollica, Zuppigno, Gentile, Scorzo, Mazzaro, Carparo. Between these the mazzaro and the carparo show some resistance values remarkable higher than the others. 9 Sassi, whose name means "stones', is a fascinating urban quarter of Matera built in the tufaceous rock. IOThey are ali villages and towns in Basilicata. 11 In tigs 3 and 4, we show an example of vault built with cylindrical elements in terracotta in S. Lucia Church in Calvello. During restoration works, superintended by Nicola Masini in the year 1994-95, it was possible to study this interesting building technology. 12The opus craticium is a typycal roman masonry, in which the builders make use also of lathes of wood, as a trellis (With regard to this see Adam J.-P ., L 'arte di costruire presso i Romani. Materiali e tecniche, Milano 1989, pp. 132-134). This old technology is also common in the architecture characterized by the use of cIay, as binder material. 13 Ferrante B., Le Pergamenedella Chiesa della Ss. Trinità di Potenza, in "Archivio Storico della Calabria e Lucania" (1964): - doc. X, 13 marzo 1300, p. 73 : " .. cedimus domum unam ... subscriptis finibus circumdatam. ab uno latere ipsius tenet Gofridus de Saponaria mediante graticia cammuni .. " - doc. XIV, 15 settembre 1306, pp. 78-79: " .. vendo e trado .. domum unam meam sitam on Potentia hiis finibus circumdatam : ab uno latere tenes tu idem Leonardus mediante graticia communi .. ".

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Figs 3-4. Calvello (PZ), S.Lucia Church. Vault built with pignatte: cylindrical elements in terracotta.

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Figs. 5-6. Ferrandina (MT), example of historical building. Section and particular.