# Geochemical study of the luting and coating of medieval watercraft from the ship timbers discovered in the citadel of al-Balīd, Oman: Composition and origin

Jacques Connan, Alessandro Ghidoni, Elodie Mezzatesta, Céline Joliot, Carole Mathe, Tom Vosmer, Renaud Gley, Isabelle Bihannic, Alexia Pavan, Michael Engel, et al.

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Jacques Connan, Alessandro Ghidoni, Elodie Mezzatesta, Céline Joliot, Carole Mathe, et al. Geochemical study of the luting and coating of medieval watercraft from the ship timbers discovered in the citadel of al-Balīd, Oman: Composition and origin. Journal of Archaeological Science: Reports, 2023, 49, pp.104051. 10.1016/j.jasrep.2023.104051. hal-04116519

HAL Id: hal-04116519

https://hal.univ-lorraine.fr/hal-04116519v1

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1 Research Paper- Draft#16

2

3

4 **Geochemical study of the luting and coating of medieval watercraft from**
5 **the ship timbers discovered in the citadel of al-Balīd, Oman: composition**
6 **and origin**

7

8

9 Jacques Connan¹, Alessandro Ghidoni², Elodie Mezzatesta³, Céline Joliot³,
10 Carole Mathe³, Tom Vosmer⁴, Renaud Gley⁵, Isabelle Bihannic⁵, Alexia Pavan⁶,
11 Michael H. Engel⁷, Alex Zumberge⁸

12

13 1- University of Strasbourg, 23 rue Antoine de Saint-Exupéry, 64000-Pau,
14 France.

15 2- Institute of Arab & Islamic Studies, Centre for Islamic, University of
16 Exeter, Stocker Road, Exeter EX4 4ND, Devon, United Kingdom

17 3- IMBE-UMR 7263-CNRS, Ingénierie de la restauration des patrimoines
18 naturel et culturel, Avignon Université, UFR-ip STS, Campus Jean-Henri
19 Fabre- Pôle Agro & Sciences, 301 rue Baruch de Spinoza-BP 21239,
20 84916-Avignon Cedex 9

21 4- Department of Maritime Archaeology, Western Australian Museum, Cliff
22 St., Fremantle WA 6160, Australia; University of Western Australia, 35
23 Stirling Highway, Crawley, Western Australia 6009, Australia.

24 5- Laboratoire Interdisciplinaire des environnements continentaux ; UMR
25 7360, Site Chamois, 15 avenue du Chamois, 54500-Vandoeuvre-les-
26 Nancy

27 6- Alexia Pavan, Ministry of Heritage and Tourism, Muscat-Salalah,
28 Sultanate of Oman.

29 7- School of Geosciences, The University of Oklahoma, 100 East Boyd
30 Street, Norman, OK 73019-100, USA

31 8- GeoMark Research inc., 97748 Whithorn Drive, Houston, TX 77095,
32 USA

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37 Abstract

38 Ship timbers were discovered during the excavation of the Islamic site of al-
39 Balīd recycled in the buildings of its citadel and the Great Mosque. These
40 fragments stripped from the hulls of Indian Ocean medieval sewn vessels form
41 the largest collection of archaeological evidence for the ships sailing during the
42 Middle Islamic Period (10th–15th century CE). More than one third of the
43 timbers bears traces of a bitumen mixture used as luting and coating to seal the
ships planking to waterproof and protect their hulls, a practice generally associated with sewn-plank construction.

This paper presents the result of the GC-MS, carbon and hydrogen isotope on chromatographic fractions, and X-Ray diffraction analyses on twenty-two samples of the luting extracted from fifteen timbers from al-Balīd. The nature of the constituents of the amalgam is determined showing that the luting consists of bitumen mixed with mineral matter, fat or oil and two triterpenic resins, dammar (Dipterocarpacea) and frankincense.

The chemical signature of the bitumen indicates that it was likely sourced from two seeps in southwest Iranian: Mamatain and Ain Gir-Chersch Mehrgir-Dehluran. The origin of the bitumen might suggest that the luting was applied during the construction or repairing of Indian Ocean vessels in boatyards along the coasts of the Arabian/Persian Gulf or Southern and Eastern Arabia.

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**Keywords:** al-Balīd, Oman, medieval sewn plank boats, timbers, luting amalgam, waterproofing agents, bitumen, resin, fat, oil, steranes, terpanes, GC-MS analyses.

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# 1. Introduction

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Bitumen was an essential material in the history of the Arabian/Persian Gulf ¹since early times. People have collected this substance from natural seeps in Mesopotamia and Iran and used it for multiple purposes such as mortar, sealant, glue and waterproof agent (Connan 1999, 2012; Connan and Deschesne 1995). Because of its versatility, this material was widely traded in the Gulf since the Neolithic, as far as Oman in the Arabian Sea (Connan and Carter 2007; Connan and Van de Velde 2010).

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Bitumen also played a crucial role in the development of boat building and seafaring in Mesopotamia and the Gulf. Coastal communities used this substance to waterproof the hulls of their reed and wooden vessels, prompting both regional and international maritime trade, and enabling the flow of goods between Mesopotamia, the Gulf and Indus Valley (Cleuziou and Tosi 1994, 2000; Carter 2002). The practice of using natural bitumen to coat vessels persisted in southern Iraq (Ochsenschlager 2004; Thesiger 1954, 1964) and Iran until recently (Cooper et al. 2020).

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Yet, our knowledge of the use of this material in boatbuilding and seafaring context during the medieval period is minimal. Due to the scarcity of medieval shipwrecks in the Indian Ocean, most of the early and middle Islamic archaeological bitumen is associated with the production of ceramic vessels,

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1-Hereafter called the Gulf
such as torpedo jars, the inside of which is sealed with a thin layer of this substance (Connan et al. 2020, 2021; Stern et al. 2008, Durand 2021, Lischi et al. 2020, Tomber et al. 2020).

Our knowledge instead relies primarily on vague historical sources mentioning a wide range of materials used to seal the hulls of watercraft in the middle Islamic period. Moreover, terms such as bitumen, tar, pitch and resin are often used indiscriminately for substances that look very similar in terms of colours and physical properties but are produced from different materials (Forbes 1955). Since it is virtually impossible to distinguish all these substances by the naked eye, references to pitch and tar might actually indicate bitumen and vice versa.

Recent excavation at the Islamic site of al-Balīd (2010–2018) (Fig.1) brought to light several ship timbers of medieval vessels involved in the Indian Ocean maritime trade (Belfioretti and Vosmer 2010; Ghidoni 2021; Pavan et al. 2018; Vosmer 2017, 2019). These pieces of maritime material culture display the distinctive traits of the Indian Ocean sewn-plank technique, providing invaluable information about boatbuilding techniques and materials in the medieval period. A considerable number of the al-Balīd timbers retained preserved “bitumen”<fnref n="1" /> on their edges and surfaces used to lute the planking seams and make the hull watertight.

## 2. The site of al-Balīd

During the medieval period, the southern coast of Oman – corresponding today to the Governorate of Dhofar - was characterized by the flourishing of several settlements, involved in the long-distance trade across the Indian Ocean. Al-Balīd, known at that time by the name ẓafār, gained a role of leadership among all these centres, becoming the most important urban settlements along the southern coast of Oman (Newton and Zarins 2017). Having its flourishing period between the 13th and the 15th century, when it is mentioned in various sources (Ibn Baṭṭūṭah 1962; Smith 1985; Yule 1871) al-Balīd was a pivotal centre for the international network developed by the Rasūlids which involved Arabia, Africa, India and, furthermore, China and East Asia (Pavan and Visconti 2020).

Żafār and the whole coast of Dhofar are mentioned as centres of export for local products, such as frankincense, ambergris, myrrh, dragon's blood, aloes, benzoin, liquid storax, camels and ostriches, but also as a place of

<footnote n="1">¹ The term “bitumen” is used here without presuming its chemical composition which could be either pure bitumen or a bituminous mixture of oil, resin and pure bitumen as illustrated in the chemical analyses below.</footnote>
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distribution for goods arriving from the interior of the country or other regions of the Arabian Peninsula such as horses, or from Africa, such as rhino horns and ivory (Pavan forthcoming).

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The wealth of the ancient town finds is evinced by the numerous high-quality and expensive pottery vessels manufactured in Egypt, Iran, and China, but also in the medium-quality products, such as Yemeni, Indian, Chinese, and Far Eastern ceramics which were found in the city.

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Evidence of contacts with East Africa are barely represented by pottery items, as most of the goods were perishable, but they include some samples of copal and quite a good number of coins issued by the Sultans of Kilwa, who ruled on the eastern coast of Tanzania, between the 10th century and the first half of the 16th century (see Annucci in Pavan et al. 2020). The city of al-Balīd covers a surface of 64 ha and it has roughly the shape of an irregular rectangle (Fig. 2A). The site is apparently crossed by two major roads with smaller streets encircling buildings which presumably stood rather isolated. The defensive system was integrated by four towers towards the ocean, two others along the western and eastern sides of the site. The side facing north apparently lacks gates and only a couple of semi-circular towers have been identified at the edges of the northern fortification system. Considering also the presence of a ditch, it is possible that the northern side has more of a divisionary purpose (separating the interior from the exterior) than a functional one. An internal gate, located in the north-central part of the site (Area B) was excavated by P. Costa (1979) and it was related to a possible inner wall delimiting an earlier smaller city.

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The city itself could be divided into three main areas: a western one, with the most important buildings such as the citadel (Husn) (Fig. 2B) and the Grand Mosque located around the largest public square of the city; a central part, with private large houses and mosques, including a funerary one; and a wide, easternmost area which was possibly used to stock, load and unload goods and animals (Fig. 2A). This sector, which is now completely flat, except for a few mounds surrounded by columns, reveals the presence of small mosques and could have hosted temporary shelters and structures built of perishable materials.

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During the last four years (2016-2020) excavations have been mainly focused on the citadel (Husn al-Balīd). Six constructional phases have been identified so far on the basis of the data emerged from the archaeological investigations, recent studies on the materials (pottery, small finds, coins) and the results achieved during the activities carried out by the previous archaeological missions working at the site. To date only the last three phases (VI, V, and IV) have been stratigraphically investigated because the works still did not reach the earliest occupational levels. The investigated phases cover a time ranging from the end of the 13th to 18th century (Pavan et al. 2018, 2020).

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### 3. The timbers

During several excavations at al-Balīd's citadel and Grand Mosque, archaeologists have discovered more than fifty timbers, identified as parts of hulls of sewn boats (Belfioretti and Vosmer 2010; Ghidoni 2021; Pavan et al. 2018; Pavan et al. 2020; Vosmer 2017, 2019). These ship remains form the largest collection of archaeological evidence for ships sailing in the Indian Ocean during the Middle Islamic Period. Having fulfilled their maritime purpose, the timbers were recycled in a terrestrial context, reused as structural elements within the masonry of the site's buildings. The builders of al-Balīd used the straight timbers as levelling within the walls of the citadel to help distribute the weight of the masonry (Borgese et al. 2019), and as ceiling planks, beams, shelves and lintels (Fig. 3) (Ghidoni 2022). Evidence of boat part recycling has been found on the Red Sea coast of Egypt at Berenike (Sidebotham 2008), at Quseir al-Qadim (Blue 2006; Blue et al. 2011) and the guardroom ceiling of Fort Jesus in Mombasa (Prins 1982). The vast majority of the al-Balīd timbers consist of hull planks bearing similarities with recent sewn boats, and displaying the traits of the Indian Ocean sewn-plank construction (Fig.4), such as:

- continuous sewing through holes regularly spaced along their edges;

- vegetal fibre sewing cordage recessed in rebates on the outside of the hull;

- a caulking roll (wadding) between the planking seams and the sewing inside the hull;

- frame lashings;

- oblique dowels connecting adjacent planks;

- and luting and coating material.

The timbers are different sizes and display various fastening techniques, indicating that they once belonged to different vessels. Most of the planks (86 %) have rebates on one side: small grooves or channels between the sewing holes and the edge of the plank. This evidence indicates a single-wadding technique typical of the western Indian Ocean (Belfioretti and Vosmer 2010; Pavan et al. 2018, 2020), where these rebates connect matching holes between two planks to accommodate and protect the stitches on the outside of the hull. Inboard, the sewing is over a cushion of vegetal material (wadding) and firmly compresses it on the plank's seam. A few planks had no rebates, suggesting instead the presence of wadding under the stitching on both sides of the hull in a pattern called double-wadding (Pavan et al. 2018, 2020; Vosmer 2017), observed in the 8th-9th centuries Phanom-Surin and Belitung shipwrecks (First Regional Office of Fine Arts 2016; Flecker 2000, 2010). An illustration by Johannes Baptista van Doetechum (c.1554-1606) shows vessels sailing off Goa with a caulking roll on each side of the hull (Van Linschoten 1605) pointing to
the use of this fastening system in the western Indian Ocean at the end of the 16th century. This technique was also documented in recent sewn vessels used along the east coast of India (Kentley 1985, 2003).

Botanical analyses carried out on the timbers indicate that Indian Ocean boatbuilders used a wide range of wood species to build medieval ships. The species identified include teak (*Tectona grandis*), jujube (*Ziziphus mauritiana*), *Terminalia* spp., *Anogeissus* spp., *Caesalpinia* spp., and palm (*Palmae*: species unspecified) (Belfioretti and Vosmer, 2010; Capretti et al. 2010; Ghidoni 2021; Vosmer 2019). The sewing cordage was visually identified as coir (coconut husk), a fibre that was widely employed in western Indian Ocean sewn watercraft throughout history (Chittick 1980; Edye 1834; Hornell 1942; Hourani 1963; Stanley 1869; Vosmer 1997).

The species diversity indicated by the botanical analyses also reflects a variety of characteristics, ranging from high-quality boatbuilding wood for hull planking, such as teak and some species of *Anogeissus*, to relatively poor choices, such as palm and jujube, the latter better suited for frames than planks. Moreover, the timbers distribution is wide, being native to various areas, including East Africa, India and Southern Arabia.

Radiocarbon dating analysis on sixteen samples indicates that the felling of the trees from which these timbers were fashioned occurred between the late 10th and 15th centuries CE, suggesting a similar period for the construction of the boats (Belfioretti and Vosmer 2010; Pavan et al. 2018; Vosmer 2017, 2019; Ghidoni 2021).

## 4. Bitumen evidence from al-Balīd

One interesting aspect of the al-Balīd timbers is the presence, in more than a third of the collection, of traces of a black substance resembling bitumen (Belfioretti and Vosmer 2010; Pavan et al. 2018; Ghidoni 2021). This substance occurs on planks either with or without rebates.

A thin layer of “bitumen” is preserved on the faying edge- the surface where two planks are joined together-of seven timbers, pointing to the practice of luting, the use of a malleable material to seal the seam between two adjoining planks before their final fitting during the assemblage of the hull (Fig. 5A-B). The construction method of sewn hulls makes it impossible to make them watertight by driving caulking into their seams, in the way used in nailed ships, because the sewing cordage would be in the way. This luting activity is suggested by various ethnographic records from the western Indian Ocean (Severin 1985; Shaikh et al. 2012; Vosmer et al. 2011; Weismann et al. 2019).
In eight timbers the “bitumen” is located on the former inner surface of the plank, between the sewing holes and the edge. The best examples are BA1104065.454 and BA0604145.175, which preserved a great deal of the substance ranging in thickness between 2 and 5 mm (Fig. 5C-E). A thin dark coat of the material is visible under the wadding in BA0604128.73 and BA0604128.74, indicating that medieval boatbuilders smeared bitumen on the hull seams prior to the sewing of the planks (Fig. 5D-F).

Four planks display traces of bitumen on the outer surface. All but one, Wo37 (Fig. 6A) have a flat surface with no rebates, suggesting the presence of the wadding outboard. Traces of bitumen are located around the stitching holes of timber Wo37, and extend towards the centre of the plank, suggesting that bitumen covered the hull outboard, most likely below the waterline to increase its water tightness and address construction issues, and protect it against marine crustacea and molluscs such as barnacles and shipworms (*Teredo navalis*) (Woods Hole Oceanographic Institute 1952).

The practice of using bitumen, tar or pitch, in Indian Ocean medieval watercraft, is suggested by a number of illustrations in the *Maqāmāt* of al-Ḥarīrī (Nicolle 1989, fig. 22; Bibliothèque Nationale, Ms Arabe 6094, fol. 68) and Persian miniatures (Eastman 1950, pl. XII; Weismann 2002, fig. 21; Bibliothèque Nationale de France, Suppl. Persan 641 f. 59) depicting black hulls. Bitumen-coated vessels have persisted in Iraq (Thesiger 1954; Ochsenschalger 2004), where they are still in use in the marshlands in the southern region of the country (Jeffrey Rose, personal communication, February 2017). Five sewn *baggāras/āmeles* from Iran, which were recently acquired by Qatar Museums, were coated outboard with a thick layer of “bitumen” (Fig. 6B), proving that the practice of using this material to waterproof watercraft persisted in a maritime context until at least the second half of the 20th century (Cooper et al. 2020).

In the case of timbers BA0604159.263 and BA0604172.69, fragments of the same plank, a thick layer of this substance covers most of the former inner surface (Fig. 6C), showing “bitumen” was also sometimes used inboard (Cooper et al. 2020) (Fig. 6D). This would have protected the stitching against abrasion and sun exposure, preventing the breakage of the cordage, thus extending the life of the sewing.

In three timbers, “bitumen” appears to have been used to seal and smooth irregular surfaces. In the case of timber BA0301-106, it covers an uneven section near the sewing holes, to make it flush with the rest of the plank. Similarly, medieval boatbuilders smeared “bitumen” near the sewing holes of
timber Wo73, to seal a crack, likely caused by the drilling of an additional hole to either repair or reinforce the sewing. On plank Wo52, “bitumen” luted a broken section of a dowel.

The site of al-Balīd also provides evidence of “bitumen” not associated with the ship timbers. Recent excavations of the citadel have discovered a lump of this substance (X35). The piece is small, measuring 60 x 100mm, and provides no hints such as impressions of wood or cordage that could help to reveal its purpose (Fig. 7). However, it is possible that the lump was imported from the bitumen sources in Persia and Mesopotamia and stored at the site to be used in boat construction or repair. Alternatively, shipwrights at al-Balīd could have even stripped it from other vessels and stored it at the site to be reused.

Lastly, a layer of “bitumen” of irregular thickness was found lining the inside of a cylindrical metal vessel (X43) (Fig. 8). The “bitumen” is likely to be pure because it appears different from that seen on the ship planks and the lump X35, having a very smooth and almost glassy texture with no inclusions. The fact that the bitumen occurs primarily on the sides of the metal container may point to the use of the substance to seal the inside of the container, in a practice previously observed in ceramic vessels (Connan et al. 2020). However, it is very likely that this evidence might indicate pure bitumen stored in the vessel for subsequent use. Firstly, its thickness, exceeding 5mm, appears rather excessive if compared with that generally used to seal ceramic vessels in the region (Connan et al. 2020; Lischi et al. 2020). The material of the container also appears to strengthen this interpretation. It is indeed unlikely that a metal container would require an internal bitumen lining since, differently from unglazed ceramics, it would not have needed to be sealed. Moreover, a metal container could have been used to prepare the bituminous mixture used in the luting and coating of the vessels.

# 5. Experimental

## 5.1 Archaeological samples

We extracted 25 “bitumen” samples from 15 timbers, the lump (X35) and the seemingly pure bitumen inside the metal container (X43) (Table 1 and Fig. 7), to determine their chemical and mineralogical composition. The former helps to trace the origin of the bitumen, while the latter provides insights into the inclusions added to the bitumen to create the amalgam for maritime use. Moreover, the samples were extracted to determine whether there are differences in the “bitumen” origin and mineralogical composition which might be related to chronology or location and function of the “bitumen” on the
timbers. Lastly, we intended to investigate possible similarities between the bitumen from the timbers and those from the lump and metal container, which might indicate different stages of the bitumen amalgam preparation. Overall, the comparison between the samples provides an opportunity for insights into the use and trade of bitumen during the medieval period, as well as about maritime activities, such as boat building, repair and maintenance in the western Indian Ocean and, perhaps, at the port of al-Balīd.

The sampling process was carried out with a scalpel, using gloves to avoid any contamination of the specimens. The samples, ranging between 2-10mm thick, were taken from most of the timbers, particularly those with a thick layer of “bitumen”:

- Eleven samples from nine planks where “bitumen” was located inboard between the sewing holes and faying edge of the plank, under the wadding;

- Three samples from three planks where the substance was on the faying edge of three planks;

- Four samples from the outboard coating of four planks;

- Three samples from the inboard coating of two timbers (BA0604172.69 and BA0604159.263), which are, in fact, fragments of the same plank;

- Two samples from two timbers, where the substance was used to fill a broken dowel hole (Wo52) and to smoothen the damaged surface of the timber, around the sewing holes outboard (BA03031-106);

- One sample from the bitumen lump X35;

- One sample from the metal container X43.

Because some of the timbers had (bore) traces of “bitumen” on either their edges and between the sewing holes and the edge (under the wadding and sewing), more than one sample was extracted from those timbers.

## 5.2 Oil seeps

In order to trace the origin of the al-Balīd bitumen from the ship timbers, metal container and lump, the characteristic biomarkers and carbon and deuterium isotopes present in the ancient samples were compared against modern compositional datasets obtained from oil seeps analysed in southern Iran and Iraq (Hit, Mosul area and Kurdistan) (Fig. 9). This reference database has been consulted in previous studies (Stern et al. 2008; Connan 2011; Connan et al. 2014, Connan et al. 2020). Some complementary data were recently acquired on new oil seeps in southwest Iran given by Buyuk Ghorbani and on oils seeps from Kurdistan provided by Rzger Abdulkarim Abdula and Mohammed W. Alkhafaji which significantly increased the geographical coverage.

## 5.3 Analytical procedures
### 5.3.1 Bitumen identification

All archaeological and geological samples were subjected to the same analytical procedure at GeoMark Research Ltd. The dichloromethane extract was deasphalted using n-hexane. The desasphalted fraction was separated into saturated hydrocarbons, aromatic hydrocarbons, and resins using gravity flow column chromatography employing a 100-200 mesh silica gel support activated at 400°C prior to use. Hexane was used to elute saturates, dichloromethane to elute the aromatic hydrocarbons and dichloromethane/methanol (50:50) to elute the resin (NSO) fraction. Following solvent evaporation, the recovered fractions were quantified gravimetrically. The $C_{15+}$saturated hydrocarbon fraction was subjected to molecular sieve filtration (Union Carbide S-115 powder) after the technique described by West et al. (1990). An aliquot of the total alkane fraction was not fractionated by silicalite in order to preserve access to the n-alkanes.

GC-MS of the $C_{15+}$branched and cyclic hydrocarbon fractions was performed using an Agilent 7890A (split injection) interfaced to an Agilent 5975C mass spectrometer. The HP-2 column (50m x 0.2mm, 0.11µm film thickness) was temperature programmed from 150 °C to 325 °C at 2 °C/minute and held for 10 minutes. The mass spectrometer was run in the selected ion mode (SIM), monitoring ions *m/z* 177, 191, 205, 217, 218, 231 and 253 amu for branched and cyclic alkanes. The quantitative data were produced using peak surface.

To determine the absolute concentration of individual biomarkers, a deuterated internal standard (d4-$C_{29}$$^{aa}$a20Rsterane, Chiron lab, Norway) was added to the $C_{15+}$branched/cyclic hydrocarbon fraction. Response factors (RF) at 221 for the deuterated standard to hopane (*m/z* 191) and sterane (*m/z* 217) authentic standards were found to be 1.4 for terpanes and 1.0 for steranes. Concentration of individual biomarkers were determined using the following equation: Conc. (in ppm) = (Ht biomarker) (ng standard)/ (Ht standard) (RF) (mg B/C fraction).

The $C_{15+}$saturates, $C_{15+}$aromatics, asphaltenes and resins were analysed for their respective carbon isotope (δ¹³C, VPDB) compositions. The asphaltenes and resins were also analyzed for their stable hydrogen isotope compositions. Details for all of the methods for stable isotope analyses are described in Connan et al. (2021).

### 5.3.2 Identification of fats, oils and resins
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Analyses were carried out at the Avignon University IMBE-IRPNC laboratory. Ten mg of samples were extracted three times with 1 mL of dichloromethane, then centrifuged, finally the supernatant was derived with BSTFA/TMCS (99/1, v/v) (Sigma Aldrich) and the solution was injected into a GC-MS device. The analytical procedure was described in Mezzatesta et al. (2021a). The analyses were carried out with a ThermoFisher apparatus equipped with an 8-slot AI3000 automatic injector and a Focus GC chromatograph coupled to an ITQ 700 ion trap type mass spectrometer. The capillary column used was a GOLD TG-5MS Thermo trace (5% diphenyl and 95% dimethyl polysiloxane) with an internal diameter of 0.25 mm, a length of 30 m and a film thickness of 0.25 µm. The carrier gas used was helium with a constant flow rate of 1 mL.min⁻¹. The injector, the transfer line and the ion trap were respectively at 250, 300 and 200 °C. The electronic impact source had an ionization energy of 70 eV, an ionization time of 25,000 µs and a scan in the mass range of 40-650 m/z. The injection volume of each sample is 1 µL in splitless mode.

# 6. Results and discussion

## 6.1 Gross composition of the extractable organic matter

Gross composition data are reported in Table 2. The extractable organic matter covers a wide range, from 2% to 77.4% /weight of the sample. The average value, deduced from the treatment of the 25 samples gave 33.8 % / weight and is higher compared to the average value of 355 archaeological bituminous mixtures from the Near and Middle East, mainly Iraq, which is 23.4 % (Connan 2012). The coating of reed boats sailing in Mesopotamia and the Gulf during the Neolithic and Bronze Age (5100-1900 BCE) was found to be 17.9 % / weight. The average values for hydrocarbons (sat. + aro.) and asphaltenes of al-Balīd samples are respectively 6.0 and 73.4 % which means that the mixtures are matching the composition of archaeological bitumens (Connan 2012). At that level of interpretation, based on gross composition only, this preliminary conclusion about bitumen occurrence remains a hypothesis in regard to the real constituents of the caulking mixtures.

Plots of the gross composition data (Table 2), in two ternary diagrams (Figs. 10 and 11) differentiate the samples. Most samples cluster in the area rich in polar components, however the samples Nos. 2360 and No. 3212 are located apart (Fig. 10). The specific character of samples Nos. 2360 and 3212 is confirmed when considering the plot of hydrocarbons vs. resins vs. asphaltenes (Fig. 11). A third sample joins this group, namely No. 2362. All other samples cluster in an area with low hydrocarbons and various amounts of resins. Two samples, Nos. 3227 and 3210, are extremely devoid of saturates and aromatics and may not contain bitumen but some other components: resins, fats, oils.
Complementary detailed investigations will provide some answers. No. 3227 (Wo52) appears to be a filler over the end of a dowel driven obliquely from the outside of the plank into the faying edge of the plank above (now missing). It may have been used as a filler to smooth the surface of the plank. Gross composition of sample No. 3212 (Fig. 10) matches those of a pure bitumen with 11.1 % saturates and 14.4 % aromatics, i.e. a rather rich composition in hydrocarbons. This sample is extremely soluble in dichloromethane (61% by weight/ sample). Sample No. 3226 (Fig.11) is a slab consisting of a characteristic archaeological bituminous mixture of mostly asphaltenes and few hydrocarbons.

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## 6.2 Carbon and deuterium isotopes

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Carbon and deuterium isotopes data are listed in Table 3. A plot of δ¹³Csat (‰ / VPDB) vs. δ¹³Caro (‰ / VPDB) of al-Balīd data (Fig. 11) in comparison to linear trend curves obtained from data on 32 oil seeps of Iran and 28 oil seeps of Iraq, show that some samples (Nos. 3212, 3226, 2934bis, 3211) are close to the straight lines defined by natural oil seeps while the others are located outside of these references. One may notice that the sample No. 3212, discovered in an iron container and which is obviously a pure bitumen with its shiny conchoidal fracture, and the sample No. 3226, which is a typical bitumen slab, are falling on straight lines defined by the reference oil seeps. Most of other samples are located in the upper part of the diagram. This feature suggests that these samples are composite mixtures with “recent” additives (resins, fish oils, fats, etc.) which shift the bitumen carbon values of aromatics towards enriched values.

A plot of δDasp (‰ / SMOW) vs. δ¹³Casp (‰ / VPDB) in Figure 13, exhibits a dispersed pattern on both parameters with δDasp (‰ / SMOW) values and δ¹³Casp (‰ / VPDB) covering a wide range respectively from -180 to -60 (‰ / SMOW) for δD and -25 to -29 (‰ / VPDB) for δ¹³C (Fig. 13). The same plot restricted to oil seeps from Iran and presented in Figure 14 limits the δD range from -30 to -110 (‰ / SMOW). The report of this result in Figure 13, defined two zones: one area clustering the samples with bitumen only and another zone where bitumen is likely mixed with other ingredients to be defined by specific additional analyses. The split of samples into two populations is confirmed when considering both δ¹³Casp (‰ / SMOW) and δ¹³Cresin (‰ / SMOW) in the plot of Figure 15 where samples containing bitumen only are identified using deuterium data.

As a consequence, the data mean that both polar fractions are affected by the suspected additives and that their δ¹³C data may be also partly altered. One should remember such a possibility when considering the diagram Ts/Tm vs. δ¹³Casp (Fig. 20) as reference to trace the origin of bitumen.

512
## 6.3 Mineralogical composition

The mineralogical compositions, obtained by X-Ray diffraction on residue left after the dichloromethane extraction, are reported in Table 4. As a general statement, the major minerals (calcite, dolomite, quartz, feldspar, clays, gypsum, anhydrite) detected in the samples are those which were previously identified in archaeological bitumens from various sites in the Near East (Forbes 1955; Connan 1988; Connan et al. 2005; Connan 2007; Connan 2012; Badel and Kramm 2014). In addition to these conventional minerals, other specific minerals (siderite, hematite, talc, halite, etc.) have been found. These minerals reflect the available tempers incorporated to the bitumen when the caulking mixtures were prepared and therefore may be variable with the dockyard where the caulking paste was elaborated. Bitumen could have also been mixed near its source and exported ready to be used, or even recycled multiple times, its original composition changed in various harbours and boatyards. To explore such hypotheses, the samples containing clay minerals (kaolinite and illite) were identified in Figure 16. Seven samples correspond to samples which have $δ^{13}$Casp (‰ / VPDB) between -27.3 and -25.5 and $δ^{13}$Cresin (‰ / VPDB) between -26.3 and -25.0, i.e., samples which are obviously coming from Iran and more likely from Khuzistan and Fars. All the samples with illite also have kaolinite except for sample No. 3226. The plot of gypsum occurrence in Figure 17 leads to samples mostly with the same isotope characteristics and therefore again samples from Iran.

## 6.4 Biomarkers: steranes and terpanes (Table 5)

Ratios, calculated on the basis of severely altered patterns where some molecular structures are questionable, were discarded from the record.

Characteristic fingerprints of well-preserved samples are shown in Figure 18. Sample No. 3215 is typical of an oil seep from Iran. Terpanes do show the occurrence of $18α(H)-oleanane$ and a moderate Ts/Tm. Steranes are rather enriched in diasteranes 27Sdia and 27Rdia. Sample No. 3226 has a different terpane fingerprint with no oleanane and a low Ts/Tm ratio. Steranes are also different with very low diasteranes and no visible C27S and 27R diasteranes.

Sterane composition, expressed as % of C27$ββR+S$, $%C28ββR+S$, $%C29ββR+S$ (not shown) differentiates two groups of samples. Samples Nos. 2935, 3210, 3220, 3227, 3228 (Table 5) are depleted in C27 and C28 steranes and therefore are more biodegraded than other samples which display well preserved patterns. To trace the possible origin of bitumens, two molecular parameters already used in a previous study (Connan et al 2020) were considered. A plot of $18α(H)-oleanane$ vs. $δ^{13}$Casp (‰ / VPDB) in Figure 19A shows that sample No. 3215 falls within the population defined by oil seeps
556 from Mamatain (Khuzestan) whereas some other samples, located as al-Balīd,
557 are included in the area defined by oil seeps from Ilam-Lorestan (Ain Gir,
558 Sarkan, Siah Kuh, Dehluran, Chersh Mehrghir, Naft Safid) but not exclusively
559 for oil seeps of Litedan in eastern Iran (Hormozgan Province) and Dalaki in
560 Bushehr are also matching. Four samples (Nos. 2382, 3209-3208, 2935 and
561 2935bis) gave unexpected 18α(H)-oleanane values in regard to their
562 corresponding δ¹³Casp (‰ / VPDB) data. These samples have already been
563 defined as mixed samples where bitumen is not alone. The addition of other
564 organic ingredients may be responsible for the significant shift in the δ¹³Casp
565 (‰ / VPDB).

566 The comparison of results obtained on al-Balīd samples to samples of oil
567 seeps from Iraq (Mosul area, Hit and Kurdistan, Fig. 19B), indicates that few
568 samples in Iraq (Mishraq and Qaiara in the Mosul area and Sangaw in
569 Kurdistan) match the data of the al-Balīd samples. Three samples fall in the area
570 defined by Mishraq-Qayara in the Mosul area and Sangaw in Kurdistan and
571 three samples (Nos. 3209, 3218 and 2362) match the Zakho oil seeps located in
572 the far north of Iraq, close to Turkey.

573 As a consequence, the molecular and isotopic data tend to favour an origin
574 of the bitumen in two major areas: Mamatain (Khuzestan) and Dehluran-Ain
575 Gir-Chersh Mehrgirh (Illam). Some seeps of Iraq cannot be ruled out for both
576 their molecular and isotopic characteristics are similar to those recorded in oil
577 seeps from Iran however they are further north and rather unlikely as more
578 proximate Iranian sources are available.

579 The plot of Ts/Tm vs. δ¹³Casp (‰ / VPDB), also currently used for
580 correlation studies, confirm the diversity of the samples from al-Balīd (Fig. 20).
581 The comparison of these data to those of oil seeps from Iraq (Fig. 21) and Iran
582 (Fig. 22) brings some additional information about sources. Some samples from
583 Iraq (Mishraq and Qaiara in the Mosul area, Sangaw and Pungala in south
584 Kurdistan, and Zhako in northern Iraq) fall within the zone defined by al-Balīd
585 samples but most samples do not match the al-Balīd archaeological samples.
586 The same diagram, built with oil seeps from Iran (Fig. 22), does show that 10
587 samples from al-Balīd match the oil seeps from Mamatain on one side and
588 Dehluran-Ain Gir-Siah Kuh- Chersch Mehrghir on the other side.

589

590 The source of some samples remains unknown, but one may remember
591 that the carbon isotopes on asphaltene are not fully reliable and ascribed to
592 bitumen for they are disturbed by the other organic substances present as
593 suggested by the 18α(H)-oleanane data which are unexpected in regard to their
594 corresponding carbon isotope values. In addition, one may not exclude the use
595 of mixtures of oil seeps from different sources to prepare the medieval caulking
596 material as determined elsewhere (Connan et al. 2020; Connan et al. 2018). Oils
597 from different origins (J.Connan, unpublished) have been identified on the hull
598 of a *shahoof*, a small vessel from Dubai, formerly part of the EISCA collection
599

600

601

602

at the Eyemouth Maritime Centre, Scotland, and recently acquired by the Oman
Across the Ages Museum (OAAM) in Manah, Oman.

*Composition of the organic mixtures: bitumen, fats and resins*

603

604

605

In this study, 11 samples were analysed (samples Nos. 3210, 3215, 3218, 3221, 3222, 3223, 3225, 3226, 3227, 3228 and 3229) in order to determine the presence of organic matter.

606

607

608

609

610

611

612

613

614

615

616

617

618

619

620

621

622

623

624

625

626

627

628

629

630

631

632

633

634

635

636

The samples Nos. 3210 and 3227 demonstrated the presence of fatty
acids which are characteristic of fatty matter. It is here difficult to determine the
nature of this fatty matter because of the absence of specific fatty acids and/or
sterols. In sample No. 3210, the proportion of fatty acids such as palmitic,
stearic and oleic acids indicated a well-preserved oil while in sample No. 3227,
the occurrence of a large proportion of dicarboxylic fatty acids such as adipic,
pimelic, suberic and azelaic acids indicated the presence of an oil that is
naturally degraded with time (Mezzatesta et al. 2021b). The chromatographic
analyses of the samples No. 3221, No. 3222 and No. 3226 showed only
molecules of hopanes and steranes interpretable as the presence of bitumen. For
the other six samples referred as Nos. 3215, 3218, 3223, 3225, 3228 and 3229,
ursane and oleanane molecules were detected. These molecules are markers
indicating the presence of a triterpenic resin but the nature of this resin is
unknown considering the lack of specific biomarkers detected and/or identified.

Taking into account these new results, Figure 19 has been updated in
Figure 23 which shows that the preliminary evaluation of sample compositions,
carried out on the basis of carbon and deuterium isotopes of asphaltenes was
relatively accurate. Complementary investigations, carried out by Philippe
Schaeffer and Pierre Adam (Strasbourg Institut of Chemistry, UMR 7177,
Strasbourg University) on eleven archaeological samples and three copal
samples, excavated near tower 10, in the external part of the city wall of al-
Balīd, have shown that copal is not part of the ingredients used in the
bituminous mixtures analyzed on planks. Two triterpenic resins have been
identified as mixtures: dammar (Dipterocarpacea) and frankincense. The
presence of fats and bitumen has been confirmed by this additional study.

634

635

636

7. Discussion

637

638

639

640

Bitumen

One important outcome of the analysis on the luting and coating of the al-Balīd timbers is that the substance used is a bitumen-based amalgam. This aspect is particularly interesting because historical and archaeological evidence indicate that Indian Ocean boatbuilders used a variety of different materials to seal the
641 planking of sewn boats. In the 10th century Abū Zayd al-Sīrāfī remarks that the
642 seams and sewing holes of the boats of Siraf were caulked with oil mixed with
643 other substances (Al-Sīrafī and Ibn Fadlān 2014). Portuguese sources describe
644 the use of pitch, bitumen and resin, in the vessels they saw along the coasts of
645 East Africa and western India in the 16th century (Agius 2007; Moreland 1939;
646 Prins 1986; Stanley 1869). A dark substance on the surfaces and edges of the
647 Quseir al-Qadim sewn-ship timbers has been tentatively interpreted as bitumen,
648 but no scientific analysis has been carried out to confirm the identification (Blue
649 et al. 2011). The builders of the 9th-century Belitung shipwreck mostly used a
650 lime-based putty to seal the hull planking, posts and through-beams (Flecker
651 2000), though bitumen was found encrusted on one of its through-beams
652 (Burger et al. 2010).
653

654 The apparent homogeneity in luting material in the al-Balīd timbers clearly
655 contrasts with the heterogeneity indicated by the textual sources and other ship
656 remains of the Indian Ocean. It may also suggest that the timbers could have
657 belonged to vessels from a particular region of the Indian Ocean, which
658 privileged the use of this substance (see below). Considering that the date and
659 thickness of the timbers (Ghidoni and Pavan 2022) point to vessels of different
660 sizes and functions sailing between the late 10th and the mid-15th centuries, it
661 also suggests that bitumen amalgams were commonly used for luting and
662 coating in the Indian Ocean for at least four centuries.
663

664 This apparently common use of bitumen in the medieval Indian Ocean is also
665 important because this material is predominantly associated with Neolithic and
666 Early Bronze Age boatbuilding in the region, and more generally to reed-built
667 vessels. It is assumed that from the Iron Age, bitumen was replaced by other
668 substances, at least for coating watercraft, and thought to have gradually
669 disappeared in the Islamic era (Vosmer 2007). However, the evidence from al-
670 Balīd indicates that the use of this material in the Indian Ocean boatbuilding
671 context persisted well into the medieval period.
672

673 *Bitumen in 19-20th-century Indian Ocean sewn boats*

674 The common use of a bitumen-based compound in medieval boatbuilding as
675 suggested by the al-Balīd timbers also contrasts with the evidence from more
676 recent sewn vessels of the Indian Ocean, which indicates various materials.
677 Resin appears to have been the most common material for luting in ethnographic
678 records of the Indian Ocean (Hornell 1942; Hill 1958; Severin 1985; Agius
679 2002; Vosmer et al. 2011). Omani boatbuilders used it to impregnate the
680 wadding of the *beden seyad*, a sewn fishing boat documented in Muscat in 1839
681 (Pâris 1843). In East Africa, a paste made with mangrove bark was the preferred
682 luting for the *mitepe* planking (Lydekker 1919). In fact, bitumen-based luting and
683 coating are seldom attested in sewn boats in the region with only a few cases
684 from the Gulf and Oman. The sewn *leggāras/āmeles* of Hormuzgan, southern
685 Iran, in the collection of Qatar Museums, have their hulls covered inboard and
686 outboard by a black substance only provisionally identified as bitumen (Cooper
687 et al. 2020). However, although no chemical analysis was carried out to
688 scientifically identify the substance, interviews with Iranian boatbuilders
689 confirmed that this type of boat was generally coated with bitumen (Kalantar et
690 al. forthcoming). Chemical analysis carried out by the authors of this paper
691 identified bitumen as the luting of an Omani *kambārī*, a sewn vessel on display
692 in the Museum of the Frankincense Land, Salalah. However, this boat is a 1980s
693 reconstruction (Weismann et al. 2019), built for display only, and the bitumen
694 used in the luting could be a product recently used by the builders and might not
695 reflect past practices and materials. Other evidence from Indian Ocean sewn
696 boats might point to the use of bitumen luting. The “pitch” sealing the sewn
697 *beden* planking recorded by Chittick (1980) in Hafun, Somalia, could also have
698 been bitumen, since no analysis was carried out to confirm the nature of the
699 material. Similarly, Shaikh (2012) mentions coal-tar being used, but it is not
700 clear whether the substance was identified scientifically.

701

702

### Bitumen mixture

703

704 The other important outcome of the geochemical analysis is that the al-Balīd
705 luting samples are not made exclusively of pure bitumen. Instead, medieval
706 boatbuilders added different matter to the bitumen to create a compound, where
707 bitumen is only one of the many ingredients. This is certainly not a surprise, but
708 rather a confirmation of a practice used in boatbuilding—as well as in other
709 terrestrial purposes—in Mesopotamia, the Gulf, and perhaps Arabian Sea, in the
710 Neolithic and Bronze Age (Cleuziou and Tosi 1994; Connan et al. 2005;
711 Connan and Van de Velde 2010; Potts 1997: 100; Vosmer 2003a; 2003b).

712

713 The reason for adding modifiers of different material to the bitumen is to change
714 its physical properties and obtain a compound suitable for the use in a
715 boatbuilding context. To be used as luting, and more generally as a sealing
716 agent, this amalgam has to be waterproof; maintain a certain flexibility or
717 plasticity which prevent it from cracking; avoid melting or becoming too fluid
718 when subjected to heat and sunlight; and maintain adherence to the timber under
719 a variety of conditions, particularly when wet (Vosmer 2003a).

720

721 Tests carried out during the construction of a hypothetical 3rd millennium BC
722 bitumen-coated reed-built vessel (Vosmer 2000; 2001; 2003a; 2003b; 2007),
723 indicate that the use of mineral additives improves the working properties of
724 bitumen. The use of calcium hydroxide – Ca(OH)₂ or in particular, calcite
725 (calcium carbonate - CaCO₃) which is the predominant mineral additive in the
726 samples from al-Balīd, increases the strength and durability of the bitumen
727 without compromising its flexibility (Vosmer 2003b; Vosmer 2007).
728 Mineralogical analysis shows that boatbuilders added a large quantity of calcite
729 in the bitumen used to coat reed vessels in the Gulf and Mesopotamia during the
730 3rd millennium BC (Connan et al. 2005). This indicates not only that this
731 practice lasted several millennia, but that during this period the bitumen mixture
732 has not changed much and that similar amalgams were used for different
733 purposes in both reed and wooden vessels.

734 The mineral matter in the bitumen amalgam also makes the bitumen resistant to
735 heat exposure. This would have been a major issue in Mesopotamia and the
736 Gulf, with extremely high temperatures in summer, causing pure bitumen to
737 ‘creep’ easily, again reducing its sealing properties. Even today, calcium
738 carbonate is added to various hydrocarbon polymers to improve their impact
739 resistance and working properties, as well as being used in bituminous cements
740 and bituminous paving (ASTM 2019).
741

742 Lastly, being a considerable part of the total compound's weight, this mineral
743 matter increases the volume of the bitumen. This would have been an important
744 factor for ancient boatbuilders, enabling them to reduce the amount of bitumen
745 used thus saving on such a valuable and expensive material.
746

747 The presence of triglycerides (natural fats and oils from animal and plants) in
748 the amalgam increases the adhesive properties of bitumen (Cleuziou and Tosi
749 1994; Vosmer 2003b). Bitumen is in fact hydrophobic and does not adhere
750 easily with wood, which is hydrophilic. Natural fats and oils in small percentage
751 (2.5-3%) act as “antistripping” agents and help the bond between different
752 materials (Vosmer 2007). Their use is further necessary after the addition of the
753 mineral (inorganic) matter which reduces the adhesion of the bitumen. Another
754 important function of triglycerides is to increase the plasticity of the amalgam,
755 when the addition of minerals might make it hard and brittle, and prone to crack.
756

757 The results of the bitumen analyses do not show any correlations between their
758 geochemical signature and their location within the timbers. It does not look as
759 though medieval boatbuilders used different amalgams whether they used the
760 bitumen on the faying edge of plank or on the plank under the wadding. This
761 evidence might point to the presence of a “maritime” bitumen amalgam, used
762 for the luting, caulking and coating of Indian Ocean vessels, its differences in
763 chemical composition depending to where it was prepared. This product
764 intended for boatbuilding could have been mixed near the sources and exported
765 to maritime centres in the Indian Ocean as a ready-made product. Alternatively,
766 Indian Ocean boatyards could have imported pure bitumen from the Iranian
767 sources and that boatbuilders mixed it in situ during the construction of the
768 boats, using the same compound regardless of its location and function.
769
770

771

772

773

774

775

776

777

778

779

780

781

782

783

784

785

786

787

788

789

### *Mixture contamination (materials unintentionally added to the amalgam)*

790

791

792

793

794

795

796

797

798

799

800

801

802

803

804

805

806

807

808

809

810

811

812

The bitumen geochemical analysis does not suggest any particular trend or change of the mixture in time. Although variations occur within the chemical and mineralogical composition of the samples examined, these appear too random to suggest intentional modifications or changes of the amalgam by Indian Ocean boatbuilders during the period indicated by the date of the timbers. It is also important to note that bitumen is a material that can be recycled multiple times, and some, if not all, of the bitumen in the al-Balīd timbers could have been stripped from old vessels and reused in the building and repairing of other boats.

Because of the scarce evidence of bitumen products associated with boats from this period it is not possible to compare the amalgams from al-Balīd with other archaeological ‘bitumens’ from the region. However, the al-Balīd mixtures appear rather unique for these are diversified amalgams ranging from pure bitumen with minerals to complex mixtures with bitumen, oil, resin and minerals which have been rarely observed for this period.

One should be aware that the presence of calcite, resin, and, possibly, oil and fat, in the bitumen, could also be explained by the fact that these materials are generally associated to boatbuilding in the Indian Ocean, and could perhaps not have been part of the original mixture. For example, fish oil was widely used to preserve and maintain the planking of both sewn and nailed wooden vessels in the Indian Ocean until recently (Agius 2002; Al-Hijji 2001; Bowen 1952; Donaldson 1979; Hornell 1942, 1970; Johnstone and Muir 1962; Lorimer 1915; Miles 1919; Vosmer 1997). Various medieval sources mention the use of fish and whale oil to coat the hulls of ships sailing in the Indian Ocean (Agius 2007), a practice that appears to have been in use in the Gulf since at least the 3rd millennium (Cleuziou and Tosi 1994). Moreover, oil was also used on the stitching to protect it and keep it moist, extending the life of the ship (Severin 1982), while experiments with dry, wet and oiled sewing fibres of *Arenga pinnata* and coir (coconut husk fibre) demonstrated that soaking in oil increased the strength of the fibres (Tyrrell 2019). By smearing oil on the hull planking, medieval boatbuilders would have applied it on the luting, unintentionally mixing it with the bitumen amalgam.

Quicklime (CaO), obtained from burnt shells and corals, and goat fat are the main ingredients of the traditional antifouling (Arabic: *shaham*; Malay/Tamil/Chinese: *chunam*) of Indian Ocean watercraft (Agius 2002; Yule and Burnell 1886). The hulls of vessels were periodically coated with this material outboard below the waterline to protect them against ship worms.
813 (Teredo navalis) and barnacles (Agius 2002; Lorimer 1915; Vosmer 2007, 2017;
814 Weismann et al. 2014). References to this practice date back to the medieval
815 period in Arab, Indian and Chinese ships, as mentioned by al-Mas‘ūdī (1861)
816 and Marco Polo (Yule 1871). The use of a lime-based substance is also indicated
817 by archaeological evidence from medieval shipwrecks from China and
818 Southeast Asia (Flecker 2001; 2007; Li 1989). Timber Wo37 from al-Balīd
819 bears traces of a white substance on its outer surface which resembles chunam.
820 The amount of substance was too little to allow scientific analyses to determine
821 its chemical composition and the identification of the material. However, its
822 colour and texture match those of the Indian Ocean antifouling, corroborating
823 information provided by historical sources. As in the case of oil, chunam would
824 have coated the planking seams and luting, perhaps leaving some traces in the
825 bitumen below.

826

827 Seven samples reveal the presence of resin in the bitumen mixture. Apart from a
828 16th century Portuguese source reporting vessels in East Africa caulked with
829 black “pitch” mixed with resin and incense (Prins 1986), resin is not usually
830 associated with bitumen in boatbuilding. A lump of bitumen discovered in
831 Akkaz, Kuwait, and dated to the Partho-Sasanian Period is the only other
832 archaeological evidence for the use of resin in a bituminous compound (Connan
833 2011). The function of this mixture is still not clear, but it appears very similar
834 to substances used for mummification in Pharaonic Egypt (Connan 2011), and it
835 might not have used in a maritime context. As we have previously seen, resin
836 was widely used with the same purpose of bitumen in other sewn boats of the
837 Indian Ocean and often mentioned in the historical sources. Perhaps the bitumen
838 luting in the al-Balīd timber was applied when the vessel was resewn and
839 smeared over a previous luting made of resin, or vice versa, causing the two
840 substances to mix together.

841

842 Overall, the evidence mentioned above raised the possibility that some of the
843 materials in the bitumen amalgam on the al-Balīd timbers were not originally
844 added to the mixture by the boatbuilders. The fact that it is likely that some of
845 these materials occurred on the hull of medieval vessels, might suggest that their
846 presence in the amalgam could have been instead the result of an accidental
847 mixing at a later stage, when these elements and the bituminous mixture came
848 into contact.

849

850 Chemical analysis provides insights into the sources of the natural bitumen used
851 in the al-Balīd timbers, suggesting southwest Iran seeps for most of the samples.
852 A possible Iranian origin corroborates the only documentary source on the topic
853 by the Dominican missionary Jordanus (1863), who, in the early 14th century,
854 reports that “in Persia are springs, from which flows a kind of pitch”. A similar
855 origin for the bitumen samples is significant, because it points to this
856 geographical area as the main source of bitumen in the Indian Ocean during the
857 medieval period. It also appears to confirm a trend noted for earlier periods
858 based on the study of bitumen lining torpedo jars, which indicated a shift from
859 Iraqi to Iranian sources between the 1st and the 10th century CE.
860

861 Very little is known about the use and trade of bitumen in the medieval period,
862 but this material would have probably been transported from the natural seeps of
863 the interior to the coastal centres in the southern Iranian coast, such as Siraf,
864 Qays (Kish) and Hormuz. Unfortunately, the geochemical analysis cannot tell us
865 whether the bitumen would have reached coastal areas already mixed and ready
866 to use, or the amalgam was prepared at the boatyards before being used.
867

868 One important question raises from the identification of the bitumen sources:
869 can the origin of the bitumen help us to determine the places where the boats
870 luted with it were built? It is difficult to answer this question because material
871 origin in the Indian Ocean does not necessarily match with the places where
872 these materials were used.
873

873 It is plausible that at least some of the al-Balīd timbers belonged to ships built in
874 city ports in southern Iran. Siraf is probably the closest to the bitumen sources
875 and had strong links with southern Arabia and particularly East Africa, the latter
876 being the region where many of the timber species from the al-Balīd timbers are
877 native. Historical sources also inform that the city imported exotic wood from
878 India and East Africa (Agius 2007; Chittick 1977), while the pottery type
879 discovered during the excavations also reveals a link with East Africa
880 (Priestman 2021).
881

881 Ships from Siraf were so common in southern Arabia and Red Sea, that the
882 Arabian Sea until Yemen was also known as *Bahr Fāris*, "the sea of Fars",
883 where most of the "shipbuilders and seafaring men are Persians" (Hourani
884 1963). Hourani (1963) also states that it is probable that in the 10th century ships
885 from Siraf reached East Africa by sailing along the coast to Aden and round the
886 Somali coast, instead of choosing a direct route to Cape Guardafui, to avoid
887 Indian pirates from Socotra. Diaspora from Siraf helped the growth of ports like
888 Jedda and Aden and contributed to the development of East African centres like
889 Mogadishu, Kilwa and Malindi (Agius 2007).
890

891 However, the city of Siraf declines in the 10th century, a date earlier than the
892 date range of the al-Balīd timbers (late 10th-15th centuries CE). The island of
893 Qays (Kish), which flourished in the 11-12th centuries, and where some of the
894 merchants of Siraf moved after the city's demise, might be a better candidate as
895 a boatbuilding place for the "al-Balīd ships". Historian Yāqūt claims that the
896 ruling house of Quays had Southern Arabian origin and controlled the Arabian
897 Sea and was in fact the ruler of Oman (Goitein and Friedman 2007).
898
New Hormuz would have also been an important boatbuilding place. It was an important city port, actively involved in the Indian Ocean trade, with a seaborne empire controlling coastal centres in Oman and in the Gulf (Agius 2007).

Unfortunately, none of these Iranian coastal sites have provided direct evidence for boatbuilding facilities, let alone the use of bitumen in a maritime context, which might link the al-Balīd timbers to ships from southern Iran. In fact, the probable Iranian origin of the al-Balīd bitumen does not necessarily imply that boats were built near the material source. In a world like the Indian Ocean, with intertwined material trade networks connecting various centres along its coasts, it is likely that bitumen was one of the materials traded. As in the case of timber for shipbuilding, lacking in places like the Arabian Peninsula, Red Sea and the Gulf, luting material such as bitumen had to be imported for the construction of vessels in these regions.

However, the use of bitumen as opposed to other substances, might hint towards some regions of the western Indian Ocean, or exclude others, as possible places where the “al-Balīd” boats were built or repaired. For example, ethnographic records indicate that the preferred material to lute Indian sewn boats from the Lakshadweep, Kerala and Goa was a mixture made of resin (Shaikh et al. 2012; Varadarajan 1993; Severin 1985, Vosmer et al. 2011), which is largely available in those areas, and of good quality (Edye 1835; Regert et al. 2008). In East Africa, boatbuilders of the sewn *mitepe* smeared a thick paste of local mangrove bark to lute its hull (Hornell 1941). Although these are relatively recent evidence, one might consider it unlikely that these areas would have needed to import bitumen from Iran, when they could use locally available and cheaper material. The bitumen luting of the al-Balīd timbers, therefore, might point to boatbuilding places in the Gulf, Arabian Peninsula, and Red Sea, which have no luting material such as resin and are relatively close to the Iranian bitumen sources.

In the Gulf, Bahrain is one possible origin for some of the “al-Balīd boats”, because of its long maritime history and proximity to Iran. Archaeological excavations at Qal‘at al-Bahrain indicate that the site imported bitumen for millennia until the 16th century, the sources of which were exclusively Iranian during the medieval period (Connan et al. 1998).

Some of the al-Balīd timbers could have belonged to vessels built in al-Balīd. A city so deeply involved in maritime trade would have certainly had shipbuilding facilities. Newton and Zarins (2017), who directed the excavation at al-Balīd between 2005 and 2012, have suggested that a large complex located in the southeast limit of the site could be interpreted as a drydock. The large number of
ship timbers recycled in the citadel of the site also strongly point to the building
and repairing of watercraft (Ghidoni and Pavan 2022). Occurrence of
frankincense in the bituminous mixtures suggests at least repairs of boats at al-
Balīd. Moreover, the pure bitumen in the metal container discovered in al-
Balīd, might also be a clue for these activities at the site premises. Bitumen
could have been imported to al-Balīd and there mixed with other materials to
create the amalgam to lute the ships built or repaired at the site.

Lastly, one should also consider that the bitumen amalgam on the al-Balīd
timbers might not have necessarily been applied during the construction of the
vessel, but at a later stage. The sewing cordage of sewn boats had to be regularly
replaced, and it is also possible that the luting on the al-Balīd timbers might
have been smeared on when the vessels had been re-sewn.

954

955

956

957

## Conclusion

959

Chemical and mineralogical analyses of the luting of the al-Balīd timbers offer
information about the sources, processing and use of bitumen in the Indian
Ocean during the medieval period. They also yield insights into boatbuilding
materials and practices in the region, deepening our understanding of sewn-
plank construction during the middle Islamic period. The identification of the
timber luting as a bitumen-based compound suggests that bitumen was the
predominant material used by the coastal communities of the western Indian
Ocean to seal the planking of their vessels. The data from al-Balīd also indicates
that the use of bitumen amalgams to waterproof hulls of vessels in the region,
generally associated to much earlier periods, continued in the 10-15th centuries,
revealing the key role played by bitumen in the Indian Ocean boatbuilding
context for millennia.

Only a limited area of al-Balīd has been excavated, and a large number of ship

timbers are visible in the masonry and rubbles of the buildings. Future
excavations will offer the opportunity for further analysis to determine whether
there are changes in bitumen sources and variation in its mixture through time.

976

977

978

## Acknowledgments

979

980

We are indebted to J.B. Berut, M.-H. and A. Doumergue, D. Dessort who
carried out the analyses in Elf Aquitaine laboratories, to D. Jarvie who accepted
to analyse samples at Humble laboratories in Houston. Thank you to GeoMark
Research Limited ; the Avignon University IMBE-IRPNC Laboratory; Rzger
985 Abdulkarim Abdula and Mohammed W. Alkhafaji who expanded the database.

986 Philippe Schaeffer and Pierre Adam who carried out the characterization of
terpenic resins. The mineralogical study was done in the Pôle de compétence

988 Physico-Chimie de l'Environment, LIEC Laboratory UMR 7360 CNRS-
989 Université de Lorraine, France. The study of the timbers was possible thanks to

990 H.E. Abdul-Aziz bin Mohammed Al Rowas, former Adviser to His Majesty the
991 Sultan for Cultural Affairs, and to all his staff, Dr Said al-Salmi, Hassan al-

992 Jaberi, Ghanem al Shanfari and Ali al Kathiri for their assistance at the Museum
993 of Frankincense Land in Şalālah, where the timbers are stored. We are also

994 grateful to the Institute of Arab and Islamic Studies, University of Exeter for
995 funding the mineralogical analysis of the luting samples.

996

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1386

1387 Vosmer T (2003b). The Magan Boat Project: a process of discovery, a discovery

1388 of process. *Proceedings of the Seminar for Arabian Studies*, 33, 49-58.

1389

1390 Vosmer T (2007). *The Development of Maritime Technology in the Arabian*

1391 *Gulf and Western Indian Ocean, with special reference to Oman*. Unpublished

1392 PhD Thesis, Curtin University of Technology.

1393

1394 Vosmer T (2017). The Development of Boatbuilding Technologies and

1395 Typologies. In: Al-Salimi A, Staples E (eds.), *Oman: A Maritime History*.

1396 (*Studies on Ibadism and Oman*). Hildesheim: Georg Olms Verlag, 185-222.

1397

1398 Vosmer T (2019). Sewn Boats in Oman and the Indian Ocean. The International

1399 Journal of Nautical Archaeology, 48 (2), 302-313.

1400

1401 Vosmer T, Staples E, Belfioretti L, Ghidoni A (2011). The *Jewel of Muscat*

1402 Project: reconstructing an early ninth-century CE shipwreck. *Proceedings of the*

1403 *Seminar for Arabian Studies*, 41, 411-424.
1404

1405 Weismann N (2002). A Type of Ship on the Indian Ocean in the Fifteenth and

1406 Sixteenth Centuries, The Mariner's Mirror, 88(2), 132-143.

1407

1408 Weismann, N., Dziamski, P., Vosmer, T., Staples, E., Ghidoni, A. and Haar, L.

1409 (2014) The *Battīl and Zārūqah* of Musandam, Oman, *The International Journal*

1410 of Nautical Archaeology, **43**(2), 1-23.

1411

1412 Weismann N, Dziamski P, Haar L (2019). The *Kambārī* in the Museum of the

1413 Frankincense Land, Salalah, Oman. The International Journal of Nautical

1414 Archaeology, 48 (2), 342-359.

1415

1416 West N, Alexander R, Kagi RI (1990). The use of silicalite for rapid isolation of

1417 branched and cyclic fractions in petroleum. Organic Geochemistry 15, 499-501.

1418 Woods Hole Oceanographic Institute (1952). The History of the Prevention of

1419 Fouling. In *Marine Fouling and Its Prevention*, by US Naval Institute, 211-223.

1420 Annapolis, Maryland: George Banta Publishing Co., Menasha, WI.

1421 Yule H (1871). *The Book of Ser Marco Polo, the Venetian: Concerning the*

1422 *Kingdoms and Marvels of the East*. London: John Murray.

1423

1424 Yule H, Burnell A C (1886). *Hobson-Jobson: being a Glossary of Anglo-Indian*

1425 *Colloquial Words and Phrases, and of Kindred Terms; Etymological, Historical,*

1426 *Geographical, and Discursive*. London: John Murray.

1427

1428 Zarins J, Newton L (2017). Northern Indian Ocean Islamic Seaports and the

1429 Interior of the Arabian Peninsula, in Al-Salimi, A. and Staples, E. (eds.) *The*

1430 *Ports of Oman. (Studies on Ibadism and Oman)*. Hildesheim, Zürich and New

1431 York: Georg Olms Verlag, 57-88.

1432

1433

1434

1435 **Figure Captions**

1436

1437 Figure 1- Map showing the location of al-Balīd, Oman. (Photo: A. Ghidoni).

1438

1439 Figure 2- (A): Aerial view of al-Balīd with the main buildings excavated (Photo:

1440 A. Pavan). (B): general view of the citadel (*husn*) where the ship timbers were

1441 discovered (Photo: M. Massa).

1442
1443 Figure 3- (A): A ship beam recycled as a lintel over a small window. (B and C):
1444 Ship planks used as levelling courses in the walls of the al-Balīd citadel.
1445 (Photos: A. Ghidoni).

1446
1447 Figure 4-Outer surface of timber BA0604145.175 (above) and the main features
1448 of western Indian Ocean sewn-plank construction technique (below).

1449
1450 Figure 5- (A): “Bitumen” on the edge of timber BA1104065.454 suggesting the
1451 practice of luting the seams of the planks before their fitting. (B): The luting
1452 process, in this case carried out using dammar resin, during the construction of
1453 the al-Hariri Boat, a reconstruction of a 13th century Indian Ocean sewn
1454 merchant vessel based on the illustrations of the Maqamat al-Hariri. (C-E): A
1455 thick layer of “bitumen” covers the section between the sewing holes and the
1456 plank’s edge on timbers BA0604145.175 and BA1104065.454. (D-E): The
1457 boatbuilders of the Jewel of Muscat, a reconstruction of a 9th century sewn cargo
1458 vessel based on the Belitung shipwreck discovered in Indonesia, used dammar
1459 resin to seal the seams of the planks after their fitting and before commencing
1460 the sewing. (Photos: A. Ghidoni).

1461
1462
1463 Figure 6- (A): Timber Wo37 displaying a thin layer of “bitumen”, along with a
1464 white substance, on the outer side. (B): A baggāra/āmele from Iran, recently
1465 acquired by Qatar Museums (QM), coated outboard with a thick layer of
1466 “bitumen”. (C): “Bitumen” The boatbuilders of the Jewel of Muscat, a
1467 reconstruction of a 9th century sewn cargo vessel based on the Belitung
1468 shipwreck discovered in Indonesia, used dammar resin to seal the seams of the
1469 planks after their fitting and before commencing the sewing. Covers most of the
1470 inside face of timber BA0604172.69. (D): The thick inboard bitumen coating of
1471 a baggāra/āmele from Qatar Museums.

1472
1473 Figure 7- Bitumen lump (X-35) discovered in the recent excavations of the
1474 citadel.

1475
1476 Figure 8- Metal vessel (X43) with a coat of bitumen inside.

1477
1478 Figure 9- Map showing the reference oil seeps analyzed in Iran (after Connan et
1479 al. 2020).

1480
1481 Figure 10- Gross composition data in a ternary diagram: Saturates (%) vs.
1482 Aromatics (%) vs. Polars (%).

1483
1484 Figure 11- Gross composition data in a ternary diagram: Saturates + Aromatics
1485 (%) vs. Resins (%) vs. Asphaltenes (%).
1486 Figure 12-δ¹³Caro (‰/VPDB) vs. δ¹³Csat (‰/VPDB): comparison of al-Balīd samples to reference curves from 32 oil seeps of Iraq and 28 oil seeps of Iran.

1488
1489
1490
1491
Figure 13-δDasp (‰/SMOW) vs. δ¹³Casp (‰/VPDB): expected composition of al-Balīd samples.

1492
1493
Figure 14- δDasp (‰/SMOW) vs. δ¹³Casp (‰/VPDB) for oil seeps of Iran.

1494
1495
Figure 15- δ¹³Casp (‰/VPDB) vs. δ¹³Cresin (‰/VPDB): comparison of al-Balīd samples to the reference curves of 8 oil seeps from Iran and 32 oil seeps from Iraq. Identification of al-Balīd samples referred as containing bitumen only.

1498
1499
1500
1501
Figure 16-δ¹³Casp (‰/VPDB) vs. δ¹³Cresin (‰/VPDB) of al-Balīd samples with the identification of their clay minerals: kaolinite, kaolinite + illite, illite.

1502
1503
Figure 17-δ¹³Casp (‰/VPDB) vs. δ¹³Cresin (‰/VPDB) of al-Balīd samples with the identification of samples containing gypsum.

1505
1506
Figure 18- Mass fragmentograms of steranes (m/z 217) and terpanes (m/z 191) of two samples of al-Balīd: No. 3215 and No. 3226. Significance of abbreviations: 21St = pregnane, 22St=20-methylpregnane, 27αααS= 5α,14α,17α-cholestane
1508
1509
20S, 29αααR= 5α,14α,17α-stigmastane 20R, 29αααR= 5α,14α,17α-stigmastane 20R, 27Sdia = 13β,17α-diacholestane (20S), 27Rdia = 13β,17α-diacholestane (20R), Ts= 18α,22,29,30-trisnorneohopane, Tm = 17α,22,29,30-trisnorhopane, C29αβ = 17α,21β-30-norhopane, C31αβH = 17α,21α-hopane, C31αβHS = 17α,21β-30-homohopane(22S)

1514
1515
Figure 19- Plot of 18α(H)-oleanane vs. δ¹³Casp (‰/VPDB). Comparison of al-Balīd samples with (A) -60 oil seeps from Iran, (B) 44 oil seeps from Iraq.

1517
1518
Figure 20- Plot of Ts/Tm vs. δ¹³Casp (‰/VPDB) for the al-Balīd samples.

1519
1520
Figure 21- Plot of Ts/Tm vs. δ¹³Casp (‰/VPDB) for the oil seeps of Iraq: comparison to the al-Balīd samples.

1522
1523
Figure 22- Plot of Ts/Tm vs. δ¹³Casp (‰/VPDB) for the oil seeps of Iran: comparison to the al-Balīd samples.

1525
1526
Figure 23- δDasp (‰/SMOW) vs. δ¹³Casp (‰/VPDB): modified figure 13 according to the results of complementary chemical investigations.
1528

1529 Table 1- Basic information about the al-Balīd samples analyzed.

1530

1531 Table 2- Gross composition data on the al-Balīd samples

1532

1533 Table 3- Isotopic data on the al-Balīd samples

1534

1535 Table 4- Results of the mineralogical analysis of some samples of al-Balīd

1536

1537 Table 5- Molecular data on the al-Balīd samples

1538
<figure><img src="image_2.png" /><figcaption>Al-Balīd
(Salalah)</figcaption></figure>
A

<figure><img src="image_3.png" /></figure>

1. Citadel (husn)

2. Grand Mosque

3. Dock (?)

<figure><img src="image_4.png" /></figure>

B

<figure><img src="image_5.png" /></figure>
<figure><img src="image_6.png" /></figure>

A

<figure><img src="image_7.png" /></figure>

B

<figure><img src="image_8.png" /></figure>

C
<figure><img src="image_9.png" /></figure>

<figure><img src="image_10.png" /></figure>

Single wadding

<figure><img src="image_11.png" /><figcaption>Inboard</figcaption></figure>

<figure><img src="image_12.png" /></figure>
<figure><img src="image_13.png" /></figure>

<figure><img src="image_14.png" /></figure>

<figure><img src="image_15.png" /></figure>

<figure><img src="image_16.png" /></figure>

<figure><img src="image_17.png" /></figure>

<figure><img src="image_18.png" /></figure>
<figure><img src="image_19.png" /></figure>

A

<figure><img src="image_20.png" /></figure>

B

<figure><img src="image_21.png" /></figure>

C

EA0604173.69

<figure><img src="image_22.png" /></figure>

D
<figure><img src="image_23.png" /></figure>

10

cm
<figure><img src="image_24.png" /></figure>

20

cm
<figure><img src="image_25.png" /></figure>

LEGEND

○ Oil Seepage

▲ Archaeological site

Elevation: (in meters a.s.l.)

High : 3000

Low : 0
<figure><img src="image_26.png" /></figure>

<figure><img src="image_27.png" /></figure>
Sat. + aro (%)

100

<figure><img src="image_28.png" /></figure>

2360

luting, 1420-1440CE

3212 bitumen in container, 17th c

50

50

substance
in bag
beside
plank

Resins (%)

100

3226 lump of bitumen, 16-17th c

3227

filling outer surface 14-15th c

2933

luting, 1320-1350CE

2933bis

luting, 1320-1350CE

3210

outer coating,
no date

3211
under wadding,
interior, 1190-1240CE

Asphaltenes (%)

2362

coating on plank
1000-1400CE
<figure><img src="image_29.png" /></figure>

δ¹³Caro (‰/VPDB)

3212

32 oil seeps
from Iraq

28 oil seeps
from Iran

3226

3229

2934 bis

2934

2935 bis

2935??
<figure><img src="image_30.png" /></figure>

Bitumen

Bitumen + fish oil ?+ resin?
<figure><img src="image_31.png" /></figure>

δ¹³Casp (‰ / VPDB)
<figure><img src="image_32.png" /></figure>

$\delta^{13}$Casp (‰/VPDB)

$\delta^{13}$Cresin (‰/VPDB)
<figure><img src="image_33.png" /></figure>

$\delta^{13}$Casp (‰/VPDB)

$\delta^{13}$Cresin (‰/VPDB)
<figure><img src="image_34.png" /></figure>

$\delta^{13}$Casp (‰/VPDB)

$\delta^{13}$Cresin (‰/VPDB)
QUANTITATIVE SATURATE BIOMARKERS

ppm C30 Hopane: 256

<figure><img src="image_35.png" /></figure>

al-Balīd-#3215

<figure><img src="image_36.png" /></figure>

QUANTITATIVE SATURATE BIOMARKERS

ppm C30 Hopane: 815

<figure><img src="image_37.png" /></figure>

al-Balīd-#3226

<figure><img src="image_38.png" /></figure>
<figure><img src="image_39.png" /></figure>

A

<figure><img src="image_40.png" /></figure>

B
<figure><img src="image_41.png" /></figure>

Ts/Tm

3209
2362
3218

3211
●

3215

3225

2933

2360

2933 bis

3221

3223

2935 bis

2935

3210

3226

3208

2934 bis

2934

3229

δ¹³Casp (‰ / VPDB)
<figure><img src="image_42.png" /></figure>

Zakho

Pungala

al-Balīd

Ts/Tm

Mishraq

Sangaw

Qaiara
0.7

Ts/Tm

<figure><img src="image_43.png" /></figure>

Mamatain

<figure><img src="image_44.png" /></figure>

Mamatain

<figure><img src="image_45.png" /></figure>

Mamatain

0.6

0.5

0.4

0.3

0.2

0.1

Dehluran

Ain Gir

Ain Gir

Dehluran

Siah Kuh

Dehluran

<figure><img src="image_46.png" /></figure>

Sultan

Gel Siah

Hammam
e-Hassan

<figure><img src="image_47.png" /></figure>

Pol Dokhtar

Al Balīd

δ¹³Casp (‰ / VPDB)

-29

-28.5

-28

-27.5

-27

-26.5

-26

-25.5

-25
δDasp (‰ / VSMOW)

<figure><img src="image_48.png" /><figcaption>Fig.22</figcaption></figure>
<table><thead><tr><th>archaeological reference</th><th>lab number</th><th>date range</th><th>type of sample</th><th>comment</th></tr></thead><tbody><tr><td>BA 0604128.74A</td><td>2360</td><td>1420-1440 CE</td><td>on plank seam</td><td>brown powder which shows black to orange lumps. Pitch according to touch and odor?</td></tr><tr><td>BA 0604128.74B</td><td>2361</td><td>1420-1440 CE</td><td>substance on stitching to hold the hull planks together (probably coconut fibre rope)</td><td>brown powder with numerous minerals. Microscopic aspect: yellow-orange powder. Resins?</td></tr><tr><td>BA 0604172.69A</td><td>2362</td><td>1000-1400 CE</td><td>coating on plank</td><td>pitch aspect</td></tr><tr><td rowspan="2">BA120621-1</td><td>2933</td><td>1320-1350 CE</td><td rowspan="2">luting sample from boat plank discovered in the Husn (Fortress ) at al-Baleed-gate timber- 21/06/2012</td><td>bituminous mixture with very fine minerals, occurrence of wood fiber. Very hard texture</td></tr><tr><td>2933 bis</td><td>1320-1350 CE</td><td>big black lump, rather homogenous, extremely hard, vegetal debris visible in the freshly broken mass, bituminous aspect</td></tr><tr><td rowspan="2">BA 1104065.454.1</td><td>2934</td><td rowspan="2">1020-1160 CE</td><td rowspan="2">luting sample from boat plank discovered in the Husn (Fortress ) at al-Baleed-gate timber- 21/06/2012</td><td>very hard and black sample with fine minerals</td></tr><tr><td>2934 bis</td><td>numerous small black grains with vegetal debris visible in the mass</td></tr><tr><td rowspan="2">BA 1104065.450-1</td><td>2935</td><td rowspan="2">1020-1170 CE</td><td rowspan="2">luting sample from boat plank</td><td>composite sample with vegetal fibers + bituminous mixture. Bituminous mixture selected for analysis</td></tr><tr><td>2935 bis</td><td>black plate with traces of wood on one side</td></tr><tr><td>BA1104065.454</td><td>3208</td><td>1020-1160 CE</td><td>dark substance on the inside of the plank between the stitching and the edge</td><td>black plate with traces of wood on one side</td></tr><tr><td>BA0604159.263</td><td>3209</td><td>1280-1440 CE*</td><td>dark substance on the inside of the plank</td><td>black plate with big lumps of wood on one side. On the other side, smooth whitish surface in which minerals are not clearly visible</td></tr><tr><td>WO37</td><td>3210</td><td></td><td></td><td>numerous grains with some traces of wood. The finest grains are yellow (resin aspect?)</td></tr><tr><td>BA0604145.175</td><td>3211</td><td>1190-1240 CE*</td><td>well preserved plank with bitumen on the inner surface</td><td>typical bituminous mixture with numerous mineral grains clearly visible in the mass. Vegetal debris probably present</td></tr><tr><td>fragmentary container in iron with cylindrical shane</td><td>3212</td><td>17th century CE</td><td>solidified material inside container which appears as a pure bitumen</td><td>no residue after extraction, rare cristallized minerals</td></tr><tr><td>BA0301-106</td><td>3215</td><td>10-15th CE</td><td>traces of thick and dark substance on the outside of the plank around the sewing holes</td><td>black sample with traces of vegetals on the surface and in the mass</td></tr><tr><td>BA0604172.69</td><td>3218</td><td>1280-1440 CE*</td><td>dark substances on most of the inside plank</td><td>numerous grains which some minerals (quartz?). Some wood imprints</td></tr><tr><td>Wo 73</td><td>3220</td><td>10-15th CE</td><td>substance found near the edge of the plank between and inside the stitching holes</td><td>sample with rope and imprints of wood</td></tr><tr><td>Wo 98B</td><td>3221</td><td>1380-1418 CE*</td><td>substance found in the inner face of the plank, near the edge and above the seam</td><td>black plate whose texture seems homogenous. If there are minerals present, they are extremely fine</td></tr><tr><td>Wo 98B</td><td>3222</td><td>1380-1418 CE*</td><td>thick layer on the edge of the plank</td><td>black lumps, rather homogenous. If there are minerals present, they are extremely fine. Wood imprints at surface</td></tr><tr><td>Wo 98A</td><td>3223</td><td>1384-1422 CE*</td><td>substance on the outer surface of the plank, between the stitching holes and the edge.</td><td>very black sample with wood debris at surface. Very fine minerals in the mass</td></tr><tr><td>Wo 98D</td><td>3225</td><td>14-15th CE</td><td>Substance found on the inside of the plank, near the edge</td><td>very black plate with extremely fine minerals in the mass.</td></tr><tr><td>Husn 17.107 X35</td><td>3226</td><td>16-17th CE</td><td>lump of bitumen discovered in the citadel (Husn) of al-Balid</td><td>very black bituminous mixture with very fine minerals</td></tr><tr><td>Wo 52</td><td>3227</td><td>14-15th CE</td><td>bitumen inside a dowel on the surface of the plank</td><td>Faily pure bitumen or resin because brown-yellow appearance on small pieces</td></tr><tr><td>BA01.11.01</td><td>3228</td><td>1044-1098 CE*</td><td>small fragments of bitumen (or resin?) in a bag next to the plank</td><td>bitumen aspect with very fine minerals. Wood imprint with wood debris in the mass.</td></tr><tr><td>BA0604128.74</td><td>3229</td><td>1420-1440 CE*</td><td>dark substance under the stitching on the inner surface of the plank</td><td>brown powder with some minerals (quartz). A piece of seashell and some pieces of wood</td></tr></tbody></table>
<table><thead><tr><th>date range</th><th>type of sample</th><th>lab number</th><th>EO (%<br>weight/<br>sample<br>)</th><th>sat, (%<br>/ EO)</th><th>aro,<br>(%/EO)</th><th>sat,+aro,<br>(%/EO)</th><th>res,<br>(%/EO)</th><th>asp,<br>(%/EO)</th><th>polars =<br>res,+asp<br>(%/EO)</th></tr></thead><tbody><tr><td>1420-1440 CE</td><td>On plank seam</td><td>2360</td><td>38.5</td><td>21.8</td><td>12.1</td><td>33.9</td><td>36.6</td><td>25.7</td><td>62.3</td></tr><tr><td>1000-1400 CE</td><td>coating on plank</td><td>2362</td><td>37.4</td><td>4.2</td><td>3.4</td><td>7.6</td><td>48.1</td><td>42</td><td>90.1</td></tr><tr><td>1320-1350 CE</td><td rowspan="2">luting sample from boat plank<br>discovered in the Husn (Fortress) at<br>al-Baleed-gate timber-21/06/2012</td><td>2933</td><td>27.1</td><td>7</td><td>6</td><td>13</td><td>15.4</td><td>71.6</td><td>87</td></tr><tr><td>1320-1350 CE</td><td>2933 bis</td><td>31.7</td><td>5.7</td><td>4.2</td><td>9.9</td><td>19.3</td><td>70.8</td><td>90.1</td></tr><tr><td rowspan="2">1020-1160 CE</td><td rowspan="2">luting sample from boat plank<br>discovered in the Husn (Fortress) at<br>al-Baleed-gate timber-21/06/2012</td><td>2934</td><td>24.4</td><td>1</td><td>1.6</td><td>2.6</td><td>11</td><td>86.4</td><td>97.4</td></tr><tr><td>2934 bis</td><td>25.4</td><td>1.3</td><td>1.8</td><td>3.1</td><td>16.7</td><td>80.2</td><td>96.9</td></tr><tr><td rowspan="2">1020-1170 CE</td><td rowspan="2">luting sample from boat plank</td><td>2935</td><td>24.3</td><td>0.8</td><td>0.7</td><td>1.5</td><td>6.3</td><td>92.1</td><td>98.4</td></tr><tr><td>2935 bis</td><td>57.5</td><td>1</td><td>1.6</td><td>2.6</td><td>22.8</td><td>74.6</td><td>97.4</td></tr><tr><td>1020-1160 CE</td><td>dark substance on the inside of the<br>plank between the stitching and the<br>edge</td><td>3208</td><td>14.4</td><td>0.7</td><td>0.7</td><td>1.4</td><td>20.1</td><td>78.5</td><td>98.6</td></tr><tr><td>1280-1440 CE*</td><td>dark substance on the inside of the<br>plank</td><td>3209</td><td>31.8</td><td>0.3</td><td>0.6</td><td>0.9</td><td>19</td><td>80.1</td><td>99.1</td></tr><tr><td></td><td></td><td>3210</td><td>35.5</td><td>0.3</td><td>0.3</td><td>0.6</td><td>11.5</td><td>88</td><td>99.5</td></tr><tr><td>1190-1240 CE*</td><td>well preserved plank with bitumen<br>on the inner surface</td><td>3211</td><td>29.7</td><td>1.2</td><td>1.6</td><td>2.8</td><td>29.9</td><td>67.2</td><td>97.1</td></tr><tr><td>17th century CE</td><td>solidified material inside container<br>which appears as pure bitumen</td><td>3212</td><td>68.3</td><td>11.1</td><td>14.4</td><td>25.5</td><td>22.1</td><td>52.3</td><td>74.4</td></tr><tr><td>10-15th c CE</td><td>traces of thick and dark substance<br>on the outside of the plank around<br>the sewing holes</td><td>3215</td><td>25.7</td><td>2.1</td><td>1.4</td><td>3.5</td><td>18</td><td>78.5</td><td>96.5</td></tr><tr><td>1280-1440 CE*</td><td>dark substances on most of the<br>inside plank</td><td>3218</td><td>46.5</td><td>0.4</td><td>0.7</td><td>1.1</td><td>16.3</td><td>85.6</td><td>101.9</td></tr><tr><td>10-15th c CE</td><td>Substance found near the edge of<br>the plank between and inside the<br>stitching holes</td><td>3220</td><td>38.2</td><td>0.5</td><td>1.3</td><td>1.8</td><td>19</td><td>79.2</td><td>98.2</td></tr><tr><td>1380-1418 CE*</td><td>substance found in the inner face of<br>the plank, near the edge and above<br>the seam</td><td>3221</td><td>30</td><td>1</td><td>3.4</td><td>4.4</td><td>15.6</td><td>77</td><td>92.6</td></tr><tr><td>1380-1418 CE*</td><td>Thick layer on the edge of the plank</td><td>3222</td><td>31.2</td><td>3.5</td><td>2.6</td><td>6.1</td><td>17.8</td><td>76.1</td><td>93.9</td></tr><tr><td>1384-1422 CE*</td><td>Substance on the outer surface of<br>the plank, between the stitching<br>holes and the edge,</td><td>3223</td><td>31.3</td><td>2.2</td><td>1.8</td><td>4</td><td>20.1</td><td>75.9</td><td>96</td></tr><tr><td>14-15th c CE</td><td>Substane found on the inside of the<br>plank, near the edge</td><td>3225</td><td>29</td><td>2.5</td><td>2</td><td>4.5</td><td>22.9</td><td>72.6</td><td>95.5</td></tr><tr><td>16-17th c CE</td><td>Lump of bitumen discovered in the<br>citadel (Husn) of al-Balīd</td><td>3226</td><td>27.4</td><td>2.6</td><td>2.9</td><td>5.5</td><td>18.6</td><td>75.9</td><td>94.5</td></tr><tr><td>14-15th c CE</td><td>Bitumen inside a dowel on the<br>surface of the plank</td><td>3227</td><td>77.4</td><td>0.1</td><td>0.1</td><td>0.2</td><td>6.1</td><td>93.7</td><td>99.8</td></tr><tr><td>1044-1098 CE*</td><td>Small fragments of bitumen (or<br>resin?) in a bag next to the plank</td><td>3228</td><td>2.1</td><td>3.5</td><td>1.2</td><td>4.7</td><td>28.2</td><td>67.1</td><td>95.3</td></tr><tr><td>1420-1440 CE*</td><td>dark substance under the stitching<br>on the inner surface of the plank</td><td>3229</td><td>27.6</td><td>1.1</td><td>1.4</td><td>2.5</td><td>24.4</td><td>73.1</td><td>97.5</td></tr></tbody></table>
<table><thead><tr><th>location</th><th>date range</th><th>type of sample</th><th>lab number</th><th>δ<sup>13</sup>Csat (‰ / VPDB)</th><th>δ<sup>13</sup>Caro (‰ / VPDB)</th><th>δ<sup>13</sup>Cres (‰ / VPDB)</th><th>δ<sup>13</sup>Casp (‰ / VPDB)</th><th>δDres (‰ / SMOW)</th><th>δDrasp (‰ / SMOW)</th></tr></thead><tbody><tr><td rowspan="24">Al-Balīd</td><td>1000-1400 AD</td><td>On plank seam</td><td>2360</td><td></td><td></td><td>-25.75</td><td>-26</td><td></td><td></td></tr><tr><td>1000-1400 AD</td><td>coating on plank</td><td>2362</td><td></td><td></td><td>-26.5</td><td>-27.2</td><td></td><td></td></tr><tr><td>1320-1350 AD</td><td>luting sample from boat plank</td><td>2933</td><td>-27.1</td><td>-26.2</td><td>-26.5</td><td>-26.4</td><td></td><td></td></tr><tr><td>1320-1350 AD</td><td>discovered in the Husn (Fortress)</td><td>2933 bis</td><td>-27.2</td><td>-26</td><td>-26.5</td><td>-26.4</td><td>-70.6</td><td>-74.5</td></tr><tr><td rowspan="2">1020-1160 AD</td><td>luting sample from boat plank</td><td>2934</td><td>-28.3</td><td>-27.6</td><td>-26.5</td><td>-26.4</td><td></td><td></td></tr><tr><td>discovered in the Husn (Fortress)</td><td>2934 bis</td><td>-27.8</td><td>-27.6</td><td>-26.6</td><td>-26.9</td><td>-123.9</td><td>-110</td></tr><tr><td rowspan="2">1020-1170 AD</td><td>luting sample from boat plank</td><td>2935</td><td>-28.7</td><td>-26.2</td><td>-27.3</td><td>-28.4</td><td></td><td></td></tr><tr><td></td><td>2935 bis</td><td>-27.3</td><td>-26.5</td><td>-27.1</td><td>-28.2</td><td>-139.4</td><td>-118.5</td></tr><tr><td>1020-1160 AD</td><td>dark substance on the inside of the plank between the stitching and the edge</td><td>3208</td><td>-26.7</td><td>-27.5</td><td>-27.5</td><td>-27.2</td><td>-139.8</td><td>-138.3</td></tr><tr><td rowspan="2">1280-1440 AD*</td><td>dark substance on the inside of the plank</td><td>3209</td><td>-26.8</td><td>-26.1</td><td>-26.1</td><td>-27.2</td><td>-165.8</td><td>-157.9</td></tr><tr><td></td><td>3210</td><td>-26.6</td><td>-26.4</td><td>-26.2</td><td>-27.6</td><td>-194.9</td><td>-177.6</td></tr><tr><td>1190-1240 AD*</td><td>well preserved plank with bitumen on the inner surface</td><td>3211</td><td>-26.2</td><td>-25.6</td><td>-25.9</td><td>-25.9</td><td>-137.8</td><td>-136.7</td></tr><tr><td>17 th century AD</td><td>solidified material inside container which appears as pure bitumen</td><td>3212</td><td>-27.3</td><td>-26.9</td><td>-26.9</td><td>-27</td><td>-109</td><td>-104.4</td></tr><tr><td>10-15th AD</td><td>traces of thick and dark substance on the outside of the plank around the sewing holes</td><td>3215</td><td>-27</td><td>-26</td><td>-25.1</td><td>-25.5</td><td>-134.8</td><td>-102.1</td></tr><tr><td>1280-1440 AD*</td><td>dark substance on the inside of the plank</td><td>3218</td><td>-26.7</td><td>-25.9</td><td>-26</td><td>-27</td><td>-159.3</td><td>-137.9</td></tr><tr><td>10-15 th AD</td><td>Substance found near the edge of the plank between and inside the stitching holes</td><td>3220</td><td></td><td>-26.7</td><td>-26.8</td><td>-27.8</td><td>-167.7</td><td>-160.1</td></tr><tr><td>1380-1418 AD*</td><td>substance found in the inner face of the plank, near the edge and above the seam</td><td>3221</td><td>-27.2</td><td>-26</td><td>-26.3</td><td>-26.3</td><td>-78.4</td><td>-87.3</td></tr><tr><td>1380-1418 AD*</td><td>Thick layer on the edge of the plank</td><td>3222</td><td>-27.2</td><td>-26.1</td><td>-26.1</td><td>-26.6</td><td>-77.9</td><td>-69.4</td></tr><tr><td>1384-1422 AD*</td><td>Substance on the outer surface of the plank, between the stitching holes and the edge.</td><td>3223</td><td>-27.4</td><td>-26.3</td><td>-25.7</td><td>-26.7</td><td>-120.4</td><td>-120.5</td></tr><tr><td>14-15th AD</td><td>Substane found on the inside of the plank, near the edge</td><td>3225</td><td>-27</td><td>-25.7</td><td>-25.9</td><td>-26.3</td><td>-103.8</td><td>-107.6</td></tr><tr><td>16-17th AD</td><td>Lump of bitumen discovered in the citadel (Husn) of al-Balid</td><td>3226</td><td>-28.4</td><td>-28.1</td><td>-28.3</td><td>-27.9</td><td>-72.2</td><td>-72.4</td></tr><tr><td>14-15th AD</td><td>Bitumen inside a dowel on the surface of the plank</td><td>3227</td><td></td><td>-26.9</td><td>-26.9</td><td>-28.4</td><td>-141.7</td><td>-152.4</td></tr><tr><td>1044-1098 AD*</td><td>Small fragments of bitumen (or resin?) in a bag next to the plank</td><td>3228</td><td></td><td>-27.7</td><td>-27.9</td><td>-28.9</td><td>-117.7</td><td>-123.2</td></tr><tr><td>1420-1440 AD*</td><td>dark substance under the stitching on the inner surface of the plank</td><td>3229</td><td>-27.8</td><td>-26.9</td><td>-26</td><td>-26</td><td>-124</td><td>-116.9</td></tr></tbody></table>
<table><thead><tr><th>n°<br>échantillon</th><th>site</th><th>date range</th><th>Quartz</th><th>Calcite<br>CaCO3</th><th>Dolomite<br>CaMg(CO3)2</th><th>Albite<br>NaAlSi3O8</th><th>Gypsum<br>(CaSO4,<br>2H2O)</th><th>Anhydrite<br>(CaSO4)</th><th>Bassanite<br>(CaSO4<br>0.5H2O)</th><th>Muscovite-<br>2M#1</th><th>Kaolinite</th><th>Illite</th><th>Clinoenstatite<br>MgSiO3</th><th>Microcline<br>KAISi3O8</th><th>Halloysite<br>Al2O3.2SiO2<br>.2H2O</th><th>Talc<br>Mg3SiO4O10(O<br>H)2</th><th>Hematite<br>(Fe2O3)</th><th>Siderite<br>(FeCO3)</th><th>Halite NaCl</th></tr></thead><tbody><tr><td>3208</td><td rowspan="14">Al-Baleed</td><td>1020-1160 AD</td><td>XXXX</td><td style="background-color: #ffff00;">XX</td><td>XX</td><td>x</td><td></td><td></td><td></td><td>x</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>3209</td><td>1280-1440 AD</td><td>XXXX</td><td style="background-color: #ffff00;">XX</td><td></td><td>x</td><td>x</td><td></td><td></td><td>x</td><td>x</td><td></td><td></td><td></td><td></td><td></td><td>xx</td><td></td><td></td></tr><tr><td>3211</td><td>1160-1260 AD</td><td>XXX</td><td style="background-color: #ffff00;">XXXX</td><td></td><td>x</td><td>x</td><td></td><td>x</td><td>x</td><td>x</td><td></td><td></td><td></td><td></td><td></td><td>x</td><td></td><td></td></tr><tr><td>2934bis</td><td>1020-1160 AD</td><td>XXXX</td><td style="background-color: #ffff00;">XX</td><td>x</td><td>x</td><td>x</td><td>x</td><td></td><td>x</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>2935</td><td>1020-1170 AD</td><td>XXXX</td><td style="background-color: #ffff00;">XXX</td><td>x</td><td>x</td><td>x</td><td>x</td><td></td><td>x</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>3228</td><td>1028-1184 AD</td><td>XX</td><td style="background-color: #ffff00;">XXXX</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>2933bis</td><td>1320-1350 AD</td><td>XX</td><td style="background-color: #ffff00;">XXXX</td><td>x</td><td>x</td><td>x</td><td>x</td><td>x</td><td></td><td>x</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>3218</td><td>1260-1400 AD</td><td>XXXX</td><td style="background-color: #ffff00;">XX</td><td>x</td><td>x</td><td>x</td><td></td><td></td><td></td><td>x</td><td></td><td></td><td></td><td></td><td></td><td></td><td>x</td><td></td></tr><tr><td>3221</td><td>1300-1369 AD</td><td>XX</td><td style="background-color: #ffff00;">XXXX</td><td></td><td>x</td><td>x</td><td>x</td><td></td><td></td><td></td><td>x</td><td>x</td><td></td><td></td><td></td><td></td><td></td><td>x</td></tr><tr><td>3222</td><td>1300-1369 AD</td><td>XXX</td><td style="background-color: #ffff00;">XXXX</td><td>x</td><td>x</td><td></td><td></td><td></td><td></td><td></td><td>x</td><td>x</td><td>x</td><td></td><td></td><td></td><td></td><td>x</td></tr><tr><td>3223</td><td>1304-1364 AD</td><td>XXXX</td><td style="background-color: #ffff00;">XXXX</td><td>XX</td><td>x</td><td></td><td></td><td></td><td></td><td>x</td><td>x</td><td>x</td><td>x</td><td></td><td></td><td></td><td>x</td><td></td></tr><tr><td>3215</td><td>10-15th AD</td><td>XXX</td><td style="background-color: #ffff00;">XXXX</td><td>XX</td><td>x</td><td></td><td></td><td></td><td></td><td>x</td><td>x</td><td>x</td><td>x</td><td>x</td><td></td><td></td><td>x</td><td></td></tr><tr><td>3225</td><td>14-15th AD</td><td>XX</td><td style="background-color: #ffff00;">XXXX</td><td>x</td><td>x</td><td>x</td><td></td><td></td><td></td><td></td><td>x</td><td>x</td><td>x</td><td>x</td><td>x</td><td></td><td></td><td></td></tr><tr><td>3226</td><td>16-17th AD</td><td>XXXX</td><td style="background-color: #ffff00;">XXXX</td><td>x</td><td>x</td><td>x</td><td></td><td></td><td></td><td></td><td>x</td><td>x</td><td>x</td><td>x</td><td>x</td><td></td><td></td><td></td></tr><tr><td>3229</td><td>1400-1460 AD</td><td>XX</td><td style="background-color: #ffff00;">XXX</td><td></td><td>x</td><td>x</td><td>x</td><td>x</td><td></td><td>x</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>3232</td><td>Al Baleed-Chunam</td><td>14-15th AD</td><td>x</td><td style="background-color: #ffff00;">XXXX</td><td>x</td><td>x</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>x</td></tr></tbody></table>

<figure><img src="image_49.png" /></figure>

calcite

<figure><img src="image_50.png" /></figure>

magnesian calcite

(Mg.064Ca.936)(CO3)
<table><thead><tr><th>Lab number</th><th>C30hopane ppm</th><th>Ts/Tm</th><th>Olean/Hop</th><th>GA/C31HR</th><th>ster/terp</th><th>Rear/Reg</th><th>C27ββR+S</th><th>C28ββR+S</th><th>C29ββR+S</th><th>C29ββS/C29ααR</th><th>steranes</th><th>terpanes</th></tr></thead><tbody><tr><td>2360</td><td></td><td>0.43</td><td>0</td><td>0.32</td><td></td><td></td><td></td><td></td><td></td><td></td><td>preserved</td><td>preserved</td></tr><tr><td>2362</td><td></td><td>0.62</td><td>0.91</td><td>0.25</td><td></td><td></td><td></td><td></td><td></td><td></td><td>altered</td><td>preserved</td></tr><tr><td>2933</td><td>116</td><td>0.43</td><td>0.03</td><td>0.44</td><td>0.16</td><td>0.17</td><td>26.7</td><td>33.4</td><td>39.9</td><td></td><td>slightly altered?</td><td>preserved</td></tr><tr><td>2933 bis</td><td>93</td><td>0.39</td><td>0.02</td><td>0.52</td><td>0.22</td><td>0.29</td><td>27.8</td><td>31.4</td><td>40.8</td><td>0.98</td><td>slightly altered</td><td>well preserved</td></tr><tr><td>2934</td><td>760</td><td>0.11</td><td>0.01</td><td>0.56</td><td>0.11</td><td>0.12</td><td>24.7</td><td>25.5</td><td>49.8</td><td></td><td>preserved</td><td>preserved</td></tr><tr><td>2934 bis</td><td>439</td><td>0.11</td><td>0.01</td><td>0.55</td><td>0.14</td><td>0.12</td><td>25.1</td><td>24.5</td><td>50.4</td><td>1.77</td><td>preserved</td><td>preserved</td></tr><tr><td>2936</td><td>116</td><td>0.33</td><td>0.02</td><td>0.51</td><td>0.09</td><td>0.08</td><td>16.7</td><td>35.1</td><td>48.3</td><td></td><td>slightly altered</td><td>preserved</td></tr><tr><td>2935 bis</td><td>124</td><td>0.22</td><td>0.2</td><td>0.43</td><td>0.32</td><td>0.15</td><td>14</td><td>9.8</td><td>76.3</td><td></td><td>altered</td><td>slightly altered?</td></tr><tr><td>3208</td><td>681</td><td>0.11</td><td>0.01</td><td>0.53</td><td>0.13</td><td>0.13</td><td>24</td><td>23.4</td><td>52.6</td><td>1.62</td><td>preserved-slightly altered</td><td>preserved</td></tr><tr><td>3209</td><td>242</td><td>0.63</td><td>0.65</td><td>0.22</td><td>0.55</td><td>0.31</td><td>22.5</td><td>22.6</td><td>54.9</td><td>0.66</td><td>altered</td><td>slightly altered?</td></tr><tr><td>3210</td><td>5</td><td>0.2</td><td></td><td>0.06</td><td>8.16</td><td>0.04</td><td>4.7</td><td>17.9</td><td>77.4</td><td>0.26</td><td>severely altered</td><td>severely altered</td></tr><tr><td>3211</td><td>116</td><td>0.61</td><td></td><td>0.2</td><td>0.42</td><td>0.63</td><td>29.9</td><td>27.5</td><td>42.6</td><td>30.2</td><td>altered</td><td>altered</td></tr><tr><td>3212</td><td>48</td><td>0.38</td><td>0.01</td><td>0.18</td><td>0.24</td><td>0.26</td><td>30.3</td><td>24.6</td><td>45.1</td><td>1.19</td><td>preserved</td><td>preserved</td></tr><tr><td>3215</td><td>256</td><td>0.54</td><td>0.15</td><td>0.22</td><td>0.35</td><td>1.27</td><td>28.6</td><td>31.2</td><td>40.2</td><td>1.36</td><td>well preserved</td><td>well preserved</td></tr><tr><td>3218</td><td>175</td><td>0.66</td><td>0.66</td><td>0.22</td><td>0.54</td><td>0.32</td><td>23.3</td><td>23.7</td><td>52.9</td><td>0.75</td><td>altered</td><td>partially altered</td></tr><tr><td>3220</td><td>15</td><td>2.48</td><td></td><td>0.14</td><td>3</td><td>0.04</td><td>4</td><td>14.8</td><td>81.2</td><td>0.31</td><td>severely altered</td><td>severely altered</td></tr><tr><td>3221</td><td>255</td><td>0.36</td><td>0.01</td><td>0.56</td><td>0.19</td><td>0.27</td><td>27.6</td><td>32.6</td><td>39.8</td><td>0.95</td><td>partly altered</td><td>preserved</td></tr><tr><td>3222</td><td>183</td><td>0.37</td><td>0.01</td><td>0.54</td><td>0.19</td><td>0.25</td><td>27.5</td><td>29.4</td><td>43.2</td><td>1.11</td><td>slightly altered</td><td>preserved</td></tr><tr><td>3223</td><td>284</td><td>0.27</td><td>0.02</td><td>0.49</td><td>0.2</td><td>0.21</td><td>29.5</td><td>26.5</td><td>44</td><td>1.32</td><td>slightly altered</td><td>preserved</td></tr><tr><td>3225</td><td>141</td><td>0.49</td><td>0.07</td><td>0.46</td><td>0.21</td><td>0.4</td><td>23.1</td><td>31.3</td><td>45.6</td><td>1.29</td><td>slightly altered</td><td>preserved</td></tr><tr><td>3226</td><td>815</td><td>0.11</td><td>0</td><td>0.53</td><td>0.18</td><td>0.06</td><td>31.5</td><td>23.6</td><td>44.9</td><td>1.43</td><td>preserved</td><td>preserved</td></tr><tr><td>3227</td><td>2</td><td></td><td>1.13</td><td>0.77</td><td>4.8</td><td>0.1</td><td>6.8</td><td>12.6</td><td>80.6</td><td>0.13</td><td>severely altered</td><td>severely altered</td></tr><tr><td>3228</td><td>22</td><td></td><td>0.18</td><td>0.4</td><td>0.3</td><td>0.77</td><td>19</td><td>13.8</td><td>67.2</td><td>0.71</td><td>severely altered</td><td>severely altered</td></tr><tr><td>3229</td><td>694</td><td>0.12</td><td>0.03</td><td>0.52</td><td>0.17</td><td>0.09</td><td>28.3</td><td>21.9</td><td>49.8</td><td>1.3</td><td>preserved</td><td>preserved</td></tr></tbody></table>