Use and trade of bitumen in antiq...
Use and trade of bitumen in antiquity and prehistory: molecular archaeology reveals secrets of past civilizations J. Connan Elf Exploration Production, CSTJF-L2 1159, Avenue Larribau, 64018-Pau Cedex, France ( email@example.com) Natural asphalt (or bitumen) deposits, oil seepage and liquid oil shows are widespread in the Middle East, especially in the Zagros mountains of Iran. Ancient people from northern Iraq, south-west Iran and the Dead Sea area extensively used this ubiquitous natural resource until the Neolithic period (7000^ 6000 BC). Evidence of earlier use has been recently documented in the Syrian desert (Boeda et al. 1996) near El Kown, where bitumen-coated ��int implements, dated to 40 000 BC (Mousterian period), have been unearthed. This discovery at least proves that bitumen was used by Neanderthal populations as hafting material to ��x handles to their ��int tools. Numerous testimonies, proving the importance of this petroleum-based material in Ancient civiliza- tions, were brought to light by the excavations conducted in the Near East as of the beginning of the century. Bitumen remains show a wide range of uses (Connan & Deschesne 1995) that can be classi��ed under several headings. First of all, bitumen was largely used in Mesopotamia and Elam as mortar in the construction of palaces (e.g. the Darius Palace in Susa), temples, ziggurats (e.g. the so-called ���T ower of Babel��� in Babylon), terraces (e.g. the famous ���Hanging Gardens of Babylon���) and exceptionally for roadway coating (e.g. the processional way of Babylon). Since the Neolithic, bitumen served to waterproof containers (baskets, earthenware jars, storage pits), wooden posts, palace grounds (e.g. in Mari and Haradum), reserves of lustral waters, bathrooms, palm roofs, etc. Mats, sarcophagi, co���ns and jars, used for funeral practices, were often covered and sealed with bitumen. Reed and wood boats were also caulked with bitumen. Abundant lumps of bituminous mixtures used for that particular purpose have been found in storage rooms of houses at Ra���s al-Junayz in Oman. Bitumen was also a widespread adhesive in antiquity and served to repair broken ceramics, ��x eyes and horns on statues (e.g. at T ell al-Ubaid around 2500 BC). Beautiful decorations with stones, shells, mother of pearl, on palm trees, cups, ostrich eggs, musical instruments (e.g. the Queen���s lyre) and other items, such as rings, jewellery and games, have been excavated from the Royal tombs in Ur. They are on view in the British Museum. With a special enigmatic material, commonly referred to as ���bitumen mastic���, the inhabitants of Susa sculpted master- pieces of art which are today exhibited in the Louvre Museum in Paris. This unique collection is presented in a book by Connan & Deschesne (1996). Last, bitumen was also considered as a powerful remedy in medical practice, especially as a disinfectant and insecticide, and was used by the ancient Egyptians to prepare mixtures to embalm the corpses of their dead. Modern analytical techniques, currently applied in the ��eld of petroleum geochemistry, have been adapted to the study of numerous archaeological bituminous mixtures found in excavations. More than 700 bituminous samples have been analysed during the last decade, using gas chromatography alone and gas chromatography coupled with mass spectrometry and isotopic chemistry (carbon and hydrogen mainly). These powerful tools, focused on the detailed analysis of biomarkers in hydrocarbon fractions, were cali- brated on various well-known natural sources of bitumen in Iraq, Syria, Iran, Bahrain and Kuwait. These reference studies have made it possible to establish the origins of bitumen from numerous archaeological sites and to document the bitumen trade routes in the Middle East and the Arabo-Persian Gulf. Using a well-documented case history, T ell el ���Oueili (5800^3500 BC) in South Mesopotamia, we will illustrate in this paper how these new molecular and isotopic tools can help us to recognize di��erent sources of bitumen and to trace the ancient trade routes through time. These import routes were found to vary with major cultural and political changes in the area under study. A second example, referring to the prehistoric period, describes bitumen traces on ��int implements, dated from Mousterian times. This discovery, from the Umm El Tlel excavations near El Kown in Syria, was reported in 1996 in Boeda et al. At that time, the origin of the bitumen had not been elucidated due to contamination problems. Last year, a ball of natural oil-stained sands, unearthed from the same archaeological layer, allowed us to determine the source of the bitumen used. This source is regional and located in the Jebel Bichri, nearly 40 km from the archaeological site. Phil. Trans. R. Soc. Lond. B (1999) 354, 33^50 33 & 1999 The Royal Society
The last case history was selected to illustrate another aspect of the investigations carried out. Recent geochemical studies on more than 20 balms from Egyptian mummies from the Intermediate, Ptolemaic and Roman periods have revealed that these balms are composed of various mixtures of bitumen, conifer resins, grease and beeswax. Bitumen occurs with the other ingredients and the balms studied show a great variety of molecular compositions (Connan 1998). Bitumen from the Dead Sea area is the most common source but some other sources (Hit in Iraq?) are also revealed by di��erent molecular patterns. The absolute amount of bitumen in balms varies from almost zero to 30% per weight (Connan & Dessort 1991 Connan 1998). Keywords: bitumen antiquity prehistory biomarker balms Egyptian mummies 1. INTRODUCTION Oil-stained rocks, i.e. oil reservoirs, solid bitumen deposits, oil and gas shows, are widespread at the surface in the Middle East, especially in the Zagros mountains of Iran (��gure 1). Numerous testimonies proving the impor- tance of these petroleum-based raw materials in ancient civilizations have been brought to light step-by-step by the various excavations conducted in the Near East since the beginning of the century. Bitumen remains show a wide range of uses, which were primarily listed by Forbes in 1954 and updated later in a second edition of his book (Forbes 1964). Prominent examples of bitumen use are cited in the Bible when referring to the ���Babel tower���, the well-known ziggurat of Babylon (Genesis 11.3), Noah���s ark (Genesis 6.14), Moses���s (basket?) cradle on the Nile (Exodus 2.3). Since the pioneering work by Forbes, summarized in his book (Forbes 1964), which is still a reliable reference today, attempts have been made to draw secrets from the available bituminous mixtures unearthed from many excavations. In the late 1970s, R. F. Marschner, a petro- leum geochemist from Amoco, undertook a collaborative study with H. T. Wright on the bituminous materials found mainly in excavations from Iran. These studies, based on the geochemical techniques available at the time in most oil companies, incidentally paved the way to exploiting chemical data stemming from the bitumen itself as well as from other components in the mixture (vegetal debris, ash, minerals, etc.. ) These milestone papers (Marschner & Wright 1978 Marschner et al. 1978) have truly opened the era of modern investigations by new geochemical tools based on modern geochemistry, namely: detailed analysis of hydrocarbons (alkanes and aromatics) with an emphasis on biomarkers (or geochem- ical fossils) by gas chromatography (GC) computerized gas chromatography^mass spectrometry (GC/MS), and even more recently by determination of isotopic values ( 13C in % per PDB) in individual compounds by gas chromatography-combustion-isotope ratio^mass spectro- metry (GC/C-IRMS). T en years ago, after having reviewed what was known through the available literature, we undertook our own investigation programme using updated knowledge and more e���cient analytical techniques, upgraded to better serve oil exploration. Available analytical techniques were slightly adapted and re��ned to adjust for the particular constraints of archaeological materials, but basically the heart of the analytical tools and knowledge improved for applied purposes in the petroleum industry were success- fully used to study archaeological bituminous materials. The goal of this paper is not to review what we have already published on bitumens found in various excava- tions, but to present a comprehensive summary which provides ���the ��avour of the subject���. Through selected examples we intend to show what kind of useful informa- tion can be brought through the study of bituminous objects from excavations and we would encourage readers to ��nd more details in the published examples. Therefore, after two sections describing the general framework of the topic, demonstrative case histories, largely unpublished, will be summarized to document the historical informa- tion that may be deduced from the study of bituminous materials present on archaeological sites. When an archaeologist ��nds such a mixture, the most common questions that spring to his mind are: 1. Is it a real bituminous mixture? How much bitumen was used? What other additives were mixed with the bitumen? For what reason? Were any changes made to the recipe through time and in di��erent areas? Is it possible to de��ne signi��cant changes in relation to variations in the use of the prepared mixtures? 2. Where did the bitumen come from? Were there any changes in sources of imported bitumen through time? Do these identi��ed trade routes agree with other historical data, especially the geopolitical and cultural framework? Ultimately, can bitumen trade-routes be traced though time as has been done for other goods such as spices, silk, copper, lapis lazuli, steatite, pearls, etc.? 2. USE OF BITUMEN IN ANTIQUITY AND PREHISTORY The diversi��ed use of bitumen in antiquity has been documented in several papers and books published by Hansen (1975), Perrodon (1989), Moorey (1994), Connan & Deschesne (1995, 1996), and Bilkadi (1996). These uses have been classi��ed under several headings in table 1. It appears that the most frequent use of bitumen was as mortar in building construction. These mortars were sometimes used for ordinary constructions, i.e. dwellings for workers and farmers, but more frequently for presti- gious buildings such as temples, palaces (e.g. the Ishtar Gate in Babylon), terraces and ziggurats (e.g. of Ur, Aqarquf, Tchoga Zanbil). This mortar was prepared by mixing bitumen with chopped straw, clay and sand. Bitumen was also extensively appreciated as a water- proo��ng agent and is still used for that purpose today on terraces and roofs, as in the famous ���Hanging Gardens of Babylon��� . Included in this category are bitumen-coated 34 J. Connan Bitumen in antiquity and prehistory Phil. Trans. R. Soc. Lond. B (1999)
mats, baskets, co���ns, storage jars, sarcophagi, bathrooms, water pipes, cisterns, wooden poles, bridges and boats. Palm mats covered with bitumen are currently applied to waterproof roofs of houses or to shroud dead bodies. In basketry, combined e��ects may have been sought: for reinforcement, to preserve from decay and for waterproo��ng. A clay bathtub sarcophagus completely covered with bitumen, from the Assyrian period, is on exhibition in the Bahrain Museum. A famous example of bitumen mixture used as caulking agent on boats is given by the gu��ah, i.e. the small round boats which were used to cross the Euphrates and the Tigris rivers at the begin- ning of the century. An example of such boats may be seen in the Navy Museum in Paris, close to the Ei��elT ower. Bitumen was the adhesive of antiquity. It was used extensively to repair broken statues or pottery to ��x ��int implements on the wooden handles of sickles to manufac- ture handles for small tools, such as chasing-chisels made Bitumen in antiquity and prehistory J. Connan 35 Phil. Trans. R. Soc. Lond. B (1999) Figure 1. Map of the Near East showing the locations of the major natural asphalt deposits (e.g. Hit-Abu Jir, Dead Sea, Kirkuk, etc.). Table 1. Main use of bitumen in antiquity and prehistory use of bitumen examples excavations with examples studied mortars in construction building temples, palaces, terraces, ��oors, ziggurats, door threshold, courtyard Mari, Babylon, Larsa, Haradum, Qal���at al- Bahrain, Mleiha, Failaka waterproo��ng agent mats, baskets, jars, water reserves, bathrooms, water pipes, cisterns, boats, sarcophagi Tell es-Sawwan, Tell el���Oueili, Qal���at al- Bahrain, Saar, Baghdad, Ra���s al-Junayz, Susa, Failaka, Tell Brak adhesive and glue sickles, tool handles, statues, jars, decoration (game, lyre, temple, pillar, ostrich egg) Tell Atij, Netiv Hagdud, Umm El Tlel, Mari, Tell Halula, Ras Shamra, Susa domestic artefacts spindle whorls, balls, dice, wall cones Tell el���Oueili, Failaka, Saar?, Qal���at al- Bahrain, Susa, Tell Brak jewellery bead, ring, gold badges on clothing or for horse harnesses Umm al-Qaiwwain, Ulu Burun, Susa, Saar sculpture sculpture, cylinder and stamp seal of Susa in bitumen mastic Susa mummi��cation mixed with conifer resin, beeswax, grease to prepare mixtures for embalming Egyptian mummies from the Queen valley and from several Museums (Lyon, Hannover, Paris)