123 the Adoption of the Arch Structure in The

ARAM, 11-12 (1999-2000), 123-130M. BARANSKI 123 THE ADOPTION OF THE ARCH STRUCTURE IN THE ARCHITECTURE OF THE ARABIAN PENINSULA MAREK BARANSKI The idea of arch and vault structure was born in the Near East. The mass employement and development of the structure had been been achieved by practising with mud brick, not with stone. The small number of architectural examples of an early date, their diversity, isolation, sometimes being out of historic context, make formation of an evolutionary sequence difficult. The situation varies depending on local and regional conditions. Problems of intercultural interactions and their role in development of the local building trade still arise. Different periods of building activity and their historical set- ting create particular difficulties in the establishment of regional originality and evaluation of levels of understanding of the principles of masonry construction. Generally speaking, the corbelled vaults were in use in ancient Mesopota- mia and Egypt already in the third millennium BC. But, presumably, the idea of the corbelled vault is even older. The remains of buildings in Arpachiyah of the Tell Halaf culture, having thick walls and round shaped rooms, can be evidence here. The Royal Tombs of Ur, the gate house of Tell Taya, Ras Shamra, tombs of Megiddo, confirm the employment of this kind of structure over a great area of Mesopotamia, Syria, Palestine and Egypt in the third Millennium BC. These monuments prove that ancient builders were well acquainted with the structure and were not afraid to construct massive buildings of a large span. The building at Tell Razuq in Mesopotamia, dated about 2900 BC, can be an important example of the evolution of the structure from corbelled to true arch. Its vaulted roof is constructed of mud brick, with layers being both corbelled and canted inward succesively. According to present knowledge, the principle of the true arch and barrel vault was developed in the second millennium BC, but the variety of mud brick structures show a significant diversity of engineering approaches. The idea of a typical radial arch was to build a structure of regular bricks set in the form of a semi circle. Each succesive layer of bricks was staggered and was also canted inward with stones and pottery sherds until the vault was set. In this system centering or temporary support was necessary. Another solution was the pitched brick vault, with brick courses resting on the previous course and successive arcs set against the first one. This technique enabled the construction of a solid and durable structure. There are numerous examples – as 124 THE ADOPTION OF THE ARCH STRUCTURE 18th century BC gate–way at Tell Dann in Israel, pitched vaults of the stables at the Ramesseum in Egypt, the gate-way in Nimrud. The system of ribbed vaults is another solution roofing narrow corridors or rooms. It may have originated from the curved reed structures common in Southern Mesopotamia. The ribbed arches were constructed of long, slightly curved bricks, set in pairs leaning against one another. The system resembles a vault only by its form. Its structural scheme is based on idea of the beams supporting each other and simultaneously interacting in distribution of the load. A spectacular innovation was the employement of wedge-shape brick voussoires. This system had distinct advantages – the domes or vaults were solid and durable. This system was not popular because of the problems with modelling the bricks. The earliest known example is the Assyrian building constructed in the 7th century BC at Tell Jemneh in Israel. The large number of mud brick buildings and the great variety of systems adopted confirms an understanding of the benefits offered by an arched structure. The long period of adoption enabled the adjustment of the system to local conditions. This resulted in individual solutions being used in different regions. But it does not mean that a better system replaced an older one. Mud brick corbelled domes in the form of a ‘bee hive' seem to to have been built since the early times. Because of the simple construction method it become common in domestic buildings, being a significant form in the region. This type of structure is still being built, especially in treeless areas. Discussing the roots of the local building trade, it is necessary to mention the light dome structure, constructed of wooden elements and rendered with mortar. Such skeleton domes have to be recognized rather as structural shells having nothing to do with arch system. But it could be an answer to problems of roofing larger spans. E. B. Smith in the publication ‘The Dome. A study in the history of ideas' pointed out that, contrary to masonry structures, domes built of timber or light domes had some advantages. They were more durable in earthquakes and, because they were light, they could be safely raised up to cover larger spans. The Near Eastern and Mesopotamian tradition of building with reeds and palm leaves can support this idea. If so, these reasonable arguments could explain the lack of masonry structures in the region in pre-Roman times. Unfortunately the evidence is slight and concerns a later period. There are historic data regarding the fire in Marmeion’s dome and that of the Martyrions in Nyssa, Nazianus, Jerusalem. It is more likely that square rooms in excavated ancient buildings had light domes. Smith suggests that deforestra- tion of the region in Roman times caused abandonment of the light dome structure, but the tradition survived until the Early Islamic period i.e. the domes of the al Aqsa Mosque, the Dome of the Rock, and the Dome of the Chain in Jerusalem. Problems of low fire resistance and lack of protection against termites presumably limited its employment to houses and buildings of M. BARANSKI 125 less importance. The problem of conformity and mutual co-existence of the light and the masonry domes needs a special study. Therefore further development of arch and vault structures should also be considered from a different perspective and several arguments should also be taken into consideration. The achievements of stone techniques and the employment of arches and vaults by Greeks and Etruscans were crucial for the development of local building techniques in the Near East. The earliest true arch construction built of stone is evidenced in Macedoania – the barrel vaults of 4th century BC tombs. Greek masons presumably gathered experience in Mesopotamia, since almost all known examples of arches and vaults in Greek architecture, except Mycenae tombs employing corbelled domes, are fully developed structures and none betrayed evidence of an initial, experimental stage. There are only a few examples of voussoires doveling in the arch structures. Perfection of the structures by Romans and their achievements in construction large span arches, cross vaulted brick structures, concrete – ‘opus caementicium' domes were the main factor in future development in the regions influenced by Ro- mans. Invention by the Romans of the load distribution system of arches incor- porated into walls, or a system of pendentives supporting the dome, were mile- stones in architecture fully adopted in Byzantium and Islam. The broad employment of domes and arches and vaults determined the distinctive character of the architecture of the Near East and the north of Arabian Peninsula. The process of adopting stone techniques occurred unequally depending on local accessibility to new ideas. Herod’s building activity in Judea was based on Roman and Greek experience. He imported not only architectural forms, but also masons and architects. Construction of Herod’s palaces or other large buidings was possible due to the fact that local masons were highly trained and the building process was well organized. Such a policy dramatically influenced the neighbouring countries, where numerous large temples had been built at the turn of the 1st century BC. Exchange of ideas due to the process of Hellenization and Romanisation of the Near East strongly influenced the local building tradition. The Qasr el Bint temple in Petra constructed at the begin- ning of the 1st century had been erected by a team of masons hired from a big- ger urban centre. The large arch of the temple dramatically contrasts with other monuments at the site. There is no impact of vault or arch structures in the tomb chambers. However, being cut in the rock, the Petra tomb chambers have larger spans than arches constructed at that time in the Near East. When one sees the vertical walls, flat ceiling and enormous weight of the rock above, one gets the impression that the concept of structural distribution of the load was only a mental idea, not a practical approach of the builder. Lack of vault- ing or corbelling to distribute the load on side walls suggests that the Naba- teans were neither aware of the danger nor afraid of it. Contrary to Petra, tombs at Hegra have corbelling of side walls, but the chambers themselves are 126 THE ADOPTION OF THE ARCH STRUCTURE smaller. It is worth consideration that the builders of Petra were not interested in advantages offered by arched structures. The minimal employment of arches is significant when compared with the numerous structures of this kind in neighbouring Judea at that time. The Nabatean Gate in Bostra erected in the end of the 1st century looks simple and its structure resembles typical Roman constructions. In the south of the Arabian Peninsula the building techniques at that time still used the post and lintel system of construction, presumably adopted from ancient Egypt and perfectly developed to take advantages of the local stone. Merchants travelling to the North had the opportunity to be encouraged by the new ideas, but nothing from the arch construction was adopted at Marib, or Hadramaut.

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