Galle lighthouse, ramparts and cockerel, by Muthu.
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Last modified:
19 Dec 2001
 

The stone anchor site
Extracts from the 1996-97 report of the Galle Harbour Project

The Arab-Indian stone anchors

The large anchor (GHP 30) is of sedimentary polymict conglomerate; maximum lenghth 3.17m, maximum width 55cm, minimum width 26cm. The broken anchor (GHP31) is of sedimentary sandstone beachrock; maximum length 74cm, maximum width 37cm, minimum width 30cm.

The large (GHP 30) and broken (GHP31) anchors are categorised as Arab-Indian. Similar examples are known from sites in the Western Indian Ocean - Mombasa, Malindi, Oman, Dwarka and the Red Sea. They are oblong in shape with a round hole in one end, presumably to take the mooring rope, and two square holes in the other end set at 90 to each other, one slightly further up the shank than the other. Through these opposite-facing holes, wooden stakes were set to act as the arms of the stock of the anchor. The type was initially identified by Honor Frost as 'grapnel' due to the transverse square holes in the lower part of the shank. This has been disputed, as the anchor shanks are rectangular in cross section whereas shafts of four armed grapnels are square or round (Kapitan, 1994:2). There is a difference in size of the two square holes in the lower portion, which also suggests that these are not grapnel anchors. Kapitan has proposed a reconstruction where the larger hole near the end of the shank actually holds a stock rather than an arm (Kapitan, 1994:2). The discovery of wood in association with GHP 30 evidences a different reconstruction. The in situ positions of the two baulks of wood in relation to the anchor holes indicates that the arm came from the hole nearest the crown. The lower hole holds a curved wooden arm and the upper hole holds a smaller piece of wood, which may be either an arm or stock.

The round hole at the other end of the shank would have had a rope directly tied through it, or perhaps another stock. The latter suggestion is qualified by other anchor examples such as a shank found in the Red Sea at Lone Mushroom, west of Ras Muhammed (Raban, 1990:302). This anchor is rectangular in cross section but only has one rectangular hole in the lower part which passes at right angles to the axis of the circular hole at the other end. This arrangement suggests that the rectangular hole held the arm of the anchor while the round hole held the stock. A timber would be required in the round hole in order for the anchor to grip into the seabed effectively (Kapitan, 1994:2).

The anchors are pre-European and could date from a very early period. In the same general area is a site known to have ceramics from a wide geographical and temporal range. This material is possibly associated with the mooring of vessels and the stone anchors. There are about three dozen* stone anchors of the Arab-Indian type catalogued in the Indian Ocean and the Red Sea. The largest concentration has been found off the coast near Qalhat, Oman in 1996. The Omani find was the greatest concentration to date*, and consisted of approximately twelve anchors or anchor fragments (Vosmer, 1997:7).

(* 1999 note: significant further finds of stone anchors were made in Qalhat in 1998.)

Twenty-four similar examples have been reported in India; however, all were being re-used as architectural elements in dock-works and forts (Tripati, 1997). Their occurrence within architecture presents us with an approximate dateable context. While the anchor may have been made for incorporation into a building or for a votive use, the function of anchors as an architectural element is probably a secondary use of the object. The primary function of an anchor as a ship's or mooring anchor presumably predates its secondary usage. It is unwise to date the anchor's two uses as contemporary, as they may have been abandoned years before being incorporated into architecture.

There has been a wide range of dates presented for this type of anchor. Some scholars categorise them as Late Bronze Age (Nibbi 1991, Frost 1963). Generally they are termed Arab-Indian which attributes this particular form to the period 5th-10th century AD. Attempts have been made to compare them to earlier anchors such as the Temple of Isidorus finds from the Alexandrian Delta which were considered by Frost to come from Roman levels (Owen, 1997:5). However, when we recall Frost (1986) Criteria for a Corpus the anchors' shapes are neglected in such a comparison. Whereas the Roman example shares some common diagnostic features, it is markedly different in shape. The Galle Harbour anchors come from an unstratified site which prevents absolute dating. The Arab-Indian anchor is best understood by a comparative archaeological analysis of the corpus of similar finds.

Timbers

Excavation of the area under the large stone anchor GHP 30 revealed timber consisting of two pieces of particularly dense wood, presumably a hardwood. Hardwood is strong and durable enough for anchoring purposes. This is the first time wood has been found in association with an Arab-Indian stone anchor. The discovery of timber will hopefully provide insight into the configuration of these anchors. The timber's position in relation to the stone shank and, in particular, the square holes, suggests that the wood functions as the arms of the anchor. The first piece raised is 980mm in length and 160mm at its widest point. The height is 104mm. It was found approximately 300mm under the sediment. There is no uniform stratigraphy as the first layers of sediment contain a random mix of broken ceramics and roofing tiles. The lack of stratigraphy implies that the area is, or has been, subject to a high degree of disturbance. The uppermost surface of the timber, as found in situ, exhibits curvature, with the majority of the original surface intact. The surface also exhibits tool marks, probably those associated with adzing. The underside has been partially degraded by marine borers, although much of the original surface remains. The original shape of the timber has been retained, and has a natural curve inwards on one edge, approximately 730mm along its length. The curve of the timber has been tooled and the edges chamfered to shape an arm. It is difficult to ascertain the original shape at this end of the arm as a large section is missing. However, in profile view, the end appears originally to have been finished in a chisel point. With this in mind, the missing portion of timber may have been symmetrical with that which remains, together forming a long, gradually tapered, V-shaped anchor arm or possibly stock. The thicker end of the timber, which was found next to the shank, is mortised, and exhibits extensive degradation by marine borers. It appears that the mortised end has snapped off, suggesting that this piece is only a portion of the original timber. The function of the mortised end is unclear. It may have performed as a locking mechanism to secure the timber into the anchor shank.

The second piece, raised two days later, is considerably larger than the first. It is 1.340m in length, 260mm wide and up to 180mm high. The timber is similar to the smaller piece as it exhibits a natural curve which has been enhanced by tooling. The timber has retained its original surface, in part. Raised knots, up to 5mm high on the upper surface of the wood, may indicate where the original surface was and the subsequent extent of degradation, although it is also conceivable that they were simply a natural part of the timber surface. The grain of the timber is visible on the surface of the thickest end. This end lay perpendicular to the anchor, under the stone shank just behind the crown. It is conceivable, regarding its position and condition, that it has broken off from another piece of timber. It may have also broken off from the hole in the anchor shank, as it was excavated from underneath the anchor shank. The curve of the timber begins 650mm from the widest end to form what may be interpreted as an arm. There is also general degradation and possible wear contributing to the curve, which prevents a full understanding of the shape. The timber may have been selected for its naturally contoured shape and then mechanically worked to create an arm which would penetrate and grip into the sediment. The end appears to finish in a point, although this too is broken or worn. Tool marks are visible, particularly in profile, although not to the same extent as the smaller timber. The underside of the large timber shows evidence of degradation due to marine borers with some of the original surface remaining. It curves upwards contributing to the hooked-arm appearance of the timber. Timber samples have been collected for identification and dendro-chronological analysis.

The nominal holding power of an anchor is related more to the size of the flukes than the weight of the shank. The addition of wooden flukes would therefore increase its relative holding power (Vosmer, 1997:8). The timbers, as we found them, are incomplete, which prevents overall size determination. Both pieces are too small to fit well within the square holes. The timbers do not appear to be heavily worn and may be close to the original size. It is also likely that the timber has swelled since immersion. If this were the case the arms may have been secured in the holes by a wedge. It has been suggested that the wooden anchor arms may have been sheathed in iron; however the find in Sri Lanka does not evidence this. The Arab-Indian anchor, as interpreted by Raban; was shaped for a safer anchorage in a coral seabed, like those fringing the Indian Ocean. He also states that this style of anchor may not have been confined to Arab boats or the result of Arab influence (Raban, 1990:303).

Working anchors, or moorings?

It is believed that large vessels would carry a complement of anchors that would be used simultaneously to secure the ship (Frost, 1983:357) or replace those lost. In high sea conditions, it was common practice to throw an anchor and drag until the rope snapped, and repeat this action until the ship was securely anchored (Owen, 1997:5). A vessel therefore carried several anchors to be used if one were lost, or to be used in conjunction with each other. The sheer size of these Arab-Indian anchors suggest that they would not be easily pulled up by hand. It is assumed that, as a result, many anchors were abandoned (Owen, 1997:5). This is one explanation for the collection of anchors we find in Galle Harbour.

On the other hand, we know that this site was a traditional mooring ground, which supports the idea that large-Arab Indian anchors were not intended for use as working ships' anchors, ie to be cast from on board, but rather as mooring anchors. This may explain the deployment of the large complete anchor GHP 30, with an estimated weight of 1000kg. Its position inshore gives credence to the idea that mooring anchors were laid carefully from a floating platform using a pulley system (Kapitan, 1994:4). In contrast the oft-cited 8th century Cypriot vase showing a stone anchor being lowered from a ship by a boom indicates that this method of deployment was also conceivable ( Frost, 1970:392).

A series of fixed moorings in the Kamba Bandina Gala area would provide ships with a useful anchorage within the harbour. The devising of such a system of moorings may have been imported by traders, as there were generally very few harbour facilities in the western Indian Ocean (Kapitan, 1994:4). The adoption of a submerged mooring facility within the pre-existing harbour at Galle suggests a precautionary measure to ensure vessels were secured when lightering cargo. However, the discovery of the remains of wooden arms in association with GHP 30 does go against this theory as, technically, arms would not have been necessary (Frost, 1970:392). Similarly, they would not stand up to long term immersion. While there appears to be no justification for arms on a mooring anchor, all these large Arab Indian examples are designed as composites.

Both suggestions of how this site came into existence are valid, as little is known about the in situ conditions of these sites. These hypotheses however, do not explain the purpose of the broken anchors. They may have been used as mooring anchors after they were broken; in this context, an example of secondary use. They also may have been dumped, if local replacements had been obtained. A comprehensive analysis of the relationship of the anchors to one another as they lie on the seabed may begin to reveal whether the in situ configuration denotes a formal mooring anchorage. The size of GHP 30 has prompted the suggestion of this site as a possible formal mooring ground. In such an instance, the size of a range of contemporary vessels cannot be calculated from the weight of such stones if they were intended as mooring stones.

The round anchor GHP 76

The round anchor GHP 76 is of sedimentary sandstone; maximum length 65cm, maximum width 49cm, maximum thickness 15cm.

GHP 76 on first examination was interpreted as a round stone anchor with a single squared perforation. The round anchor is possibly a weight anchor. This type relies on its weight, as opposed to arms, to hold a vessel. Its shape and size may indicate that it was used for a small vessel on a rocky sea floor (Vosmer, 1997:9). However, the shape of the hole is squared off, perhaps so that a wooden arm or stock may be inserted. Apical holes may also be squared off as in the Late Bronze Age Ugaritic anchors (Frost, 1970:388); however, the purpose of this square finish is unclear. The holes in the Ugaritic examples are cupular drilled, yet chiselled square on one side, perhaps to lock the wood in place and stop it rotating loose. This technique was interpreted as decorative as, in this instance, the original drill holes are narrow and round and not cut to fit square flukes (Frost, 1970:388). There is no evidence to support this in other single-hole anchors; however, square holes in the tablet, Mediterranean-style anchors have generally denoted the use of a wooden arms. It is not necessary to square off a hole if it is to be used for a hawser alone.

The shape of the anchor has some similarities to the ringstones used in the Maldives. Ringstone anchors were used for anchoring on coral reefs to prevent snagging on the coral. A forked branch could also be inserted through the hole of a ringstone, operating as a crude shank (Vosmer, 1997:17).

Both ideas concerning the identification of this anchor fail to address where it was found. The silt and sediment sea-floor of Galle Harbour does not support either theory - of it being a rock or a coral anchor. Its function as we find it in situ is probably as a temporary mooring or abandoned anchor from a smaller boat. It is possible that it is not in its original form. It may be a fragment, such as the lower corner of a Mediterranean three-hole anchor, similar to GHP 32 (Vosmer, pers.comm.). That would explain the square hole and the unusual shape.

The closest comparison to this anchor comes from Kommos in Southern Crete and comes from a definable chronological context (Shaw, 1995:282). It was dated to the late Minoan Period of 1250BC (Nibbi 1993:13). The Kommos example, artefact no. S636, is one of 5 anchor fragment finds, and it exhibits the same characteristics, including the squared-off hole, as the one found in Galle. It is approximately the same size, which would preclude its use for anything more than as a light weight anchor for a small fishing vessel. The Kommos example has been reconstructed as a triangular one-holed anchor, which was common to the Minoan Period (Nibbi, 1993:14). This type of anchor is also in use today, which makes dating this object difficult.

The four-hole Mediterranean-style anchor GHP 32

The four-hole Mediterranean-style anchor is of sedimentary sandstone; maximum length 100cm, maximum width 83cm, minimum width 40cm, maximum thickness.

This object is interpreted as a four-hole composite anchor, which essentially means that the anchor does not rely on its weight alone (Nibbi, 1991:191). The type has also been labelled Byzantine-Arab as it was common to this period (Frost, 1963:49). It was still in use until recently, in the Persian Gulf and on Arab boats in the Mediterranean, and, as a result, has been called Mediterranean in form (Frost, 1963:13). This type appears in many varying forms across a broad geographical and temporal range.

The type's interpretation as composite has recently been evidenced with the discovery of wood remains within a three-hole stone anchor from Crusader Arsuf (Appollonia) in Israel. The wood is radio-carbon dated to AD 1164-1253 (Grossman, 1996:51). The Israeli anchor is slightly smaller in dimension, with tubular piercing in the base of the anchor, as opposed to square. Wood remains were discovered in one of the lower holes (Grossman, 1996:50). The wood had been sawn carefully to fit the holes, and sat flush with the surface of the anchor on the upper- and presumably under-side. The condition and position of the wood in situ suggest that the anchor was deployed without the envisioned large wooden flukes protruding well beyond the surface of the stone (Grossman, 1996:52). This find would therefore support the idea that composite anchors were used without the arms complete, in some circumstances.

Wood has been found in association with stone anchors in two other instances. The Israel Antiquities Authority reported a three-hole anchor with a section of a fluke in a lower hole, retained by iron nails. Wood has also been found in association with medieval two- and three-hole anchors from Agde, France (Grossman, 1996:51).

The anchor GHP 32 shares characteristics with examples found in India in relation to the hole configuration and general shape. The Indian examples, in particular those from Sindhudurg Fort on the west coast are, however, more triangular in form. The date range for this form in India is from 2300 BC to the Historic Period. Their Mediterranean and Egyptian counterparts are dated to 1200-1400 BC (Tripati, 1997:55).

The GHP 32 anchor has a pock-marked surface, a result of exposure and encrustation. Only a small portion of the original surface remains. The anchor has two round holes below the apex and two square holes along the base. It is generally accepted that the top hole(s) in the anchor were for the main hawser. This is an unusual example as this style of anchor, as found in other contexts, has only one round hole below the apex. This may be a deliberate double-hole configuration to ensure the anchor stone is secured to the lifting rope, or perhaps the lower hole was added later to replace the original hawser, which is liable to break as it is only 45mm from the top of the anchor.

The number and configuration of holes on this type of anchor may be a result of the way the anchor was transported onboard ship, as opposed to the type of seabed on which it would eventually rest (Nibbi 1993:9). The anchor as we found it in situ has random channels cut into the surface, possibly wear marks from general use, the hawser rope or ropes which tethered it to the sea floor or to the ship during transportation. The square and round holes also show signs of wear.

Stone Anchor Conservation

The main conservation concern has been the issue of the stability of the stone anchors following recovery. Since a proper examination could not be carried out prior to recovery to ascertain the likely porosity of the stone, precautions were taken to ensure that the stone did not dry, thus avoiding potential damage due to salt crystallisation.

A wrapping of polythene sheet and water soaked jute bags (Gunny sacks) was used to maintain a moist environment for the anchors. To lift the large Arab-Indian anchor (GHP 30), it was bound with ropes to avoid damaging the surface; none of the original holes (for arms and hawser) were used for this procedure (other than to prevent the lateral movement of ropes during the actual lift). Chains holding the lift drums were attached to the ropes in order to prevent damage to the stone. The actual lift was not without problems but the anchor appeared to have suffered no damage as a result and it was successfully brought alongside the Dakshina Naval Base wharf. A crane transferred the anchor from the water placing it onto wood supports covered with a layer of polythene and a bed of seawater-soaked sacks. After wrapping in these materials the anchor remained moist and secure on the wharf overnight. The next day, following an assessment of the stone's condition and durability, the soft marine growth and dirty harbour sediments were removed by the use of a high pressure water blaster (this later made the work of cleaning off marine encrustation much easier and pleasant as it minimised the products and odours of decay). On completion the anchor was moved on the padded tines of a fork lift, to padded supports on the back of a truck and transported to the Maritime Museum in the Galle Fort.

Removal of the marine encrustation (mainly oyster shell, maximum 50 mm diameter) from the biggest stone anchor took some two and a half days. Five conservators used an assortment of chisels and hammers to remove the shell deposits. To avoid potential problems attributable to the crystallisation of salts, all of the anchors were regularly wetted down using a fresh water hose and buckets of water, assisted by periods of rain.

The three smaller stone anchors GHP 31, 32 and 76 have been placed in the concrete storage tank located on the jetty of the conservation laboratory. To permit desalination to take place this tank is partly filled with fresh water and will require topping up occasionally to ensure that the anchors remain fully immersed.

The porosity, and therefore potential salt contamination, of the stone of all the anchors has yet to be determined. Total immersion of the largest anchor in fresh water is desirable but requires the building of a concrete tank or alternatively a hole dug in the ground fitted with a waterproof lining. The anchor could simply be suspended from beams across the hole. Just prior to the team's departure from Galle in 1997, the decision had been made to build a tank to house the largest anchor. If the porosity of the stone is insignificant the anchor should have, at the very least, a regular fresh water dousing (daily if possible) to wash away surface salts. As with all artefacts, regular inspection must be carried out to determine whether any problems are developing.

Condition of the anchors

All the anchors recovered required removal of some encrustation, which comprised mainly bivalve mollusc shells (oysters). The upper surfaces of the largest anchor GHP 30 was densely covered in these and colonised by hydroids. The less durable surface of the broken anchor GHP 31 had been quite extensively penetrated by boring bivalve molluscs. Anchor GHP 30 also had some examples of this mollusc present.

The other anchors GHP 32 and 76 were less encrusted, due to their lower profiles and partial burial in the seabed. General sediment disturbance close to the seabed and probable cycles of burial and exposure appear to have inhibited colonisation by long-term marine organisms.

The actual stone of all the anchors remains in very good condition. Prior to removing encrustation, the surface of each was examined (test probed) to ensure due care was taken when chiselling away encrustation. The sedimentary stone of GHP 30, 31 and 32 is less durable than that of anchor GHP 76 and the modern example, which appear to be derived from igneous rock. In general the stone surfaces exhibit areas of wear and damage, but no more than might be expected considering the working life of anchors. Long-term immersion in the marine environment and colonisation by marine biota have contributed by degrading and pitting the stone surfaces. The surface of anchor GHP 76 is quite badly degraded to a depth of approximately 3-4mm. A sample of this stone reveals a very hard and crystalline interior structure quite different in appearance and colour from its outer surface. The degradation of the surface would imply long term immersion for this stone anchor; if the rate of breakdown of this stone type can be determined, then it may be possible to date it.

Timber conservation

The discovery of wood (GHP 40 and 41) associated with this anchor is a unique and important find. Despite only relatively shallow burial (300 mm approx.) the wood has endured perhaps several centuries of immersion in the sea (water depth 7m). The wood appears to be a dense and strong hardwood, which are predictable attributes for anchoring purposes. The burial medium is sand and finer sediments intermixed with broken ceramics and an assorted collection of objects from recent and past times. The diverse and random vertical mix of old and new objects in the surrounding seabed implies that the area is subject to considerable periodic disturbance, which makes the survival of this wood all the more remarkable.

The relatively compacted sediment and blackened appearance of the wood imply that anaerobic conditions were prevailing at the time of discovery. The under surfaces and one end of both pieces have suffered some marine borer attack, and this would indicate that aerobic conditions existed some time in the past as teredo cannot survive burial in anaerobic conditions. Alternatively, it may be the result of attack incurred when the anchor was in the original 'set' position. The latter conclusion may be correct as the most extensive teredo damage has occurred on the ends of the wood which were closest to the stone shank of the anchor but not on the opposite ends. At the time of discovery the largest of the two pieces of wood lay partly under the shank just behind the crown. It is probable that this wooden arm became trapped as a result of collapse due to this original borer activity.

The condition of the wood is very good. It still exhibits original surface working (adzing) and retains original shaping (curvature and chamfering). Other than the teredo damage it seems that only 1-2 mm of the outer surfaces show obvious degradation as the bulk of the wood still has the toughness and solid 'ring' of seasoned wood. Rounded-over, knot-like projections on some surfaces of the largest piece of wood (GHP 45) do not appear to be less-degraded areas, but typical wood-growth formations which are frequently visible when bark has been removed. A moist storage environment is being maintained for the wood to avoid possible shrinkage and cracking despite its apparent integrity. Controlled drying may be possible for the wood; however, the experimental nature of this procedure and the risk to such a rare find would negate this option until the extent of degradation has been accurately determined. To optimise success, the recommendation at this stage would be to conserve the wood with PEG and freeze-dry it. This conservation procedure should preferably be performed at a conservation facility with recognised expertise in this field of treatment.

In view of the proposed sampling requirement for this wood, further intrusive drilling to acquire pH profiles was not contemplated, to avoid marring the appearance of these unique finds. A selection of samples have been acquired from each piece of wood for degradation analysis, species identification and dating. After cleaning each sample was placed in a vial of fresh water. No biocide was added, to avoid contamination which affects dating investigations.

Wood in a similar state of preservation is also found at another site in Galle Harbour. The wreck at Site L, believed to be that of the Avondster, was lost in 1659. A considerable amount of this vessel's timbers, and co-incidentally a wooden anchor stock (attached to an iron anchor), have survived almost 350 years' immersion. The wood from the Arab-Indian anchor GHP 30 appears to have survived in equal if not better condition. Unless this earlier type of stone anchor was in contemporary use in the mid-17th century, the two wooden arms recovered may have survived some 500 years or more in the sands of the Galle Harbour anchorage.

Both pieces of wood were prepared for proposed transportation to the Department of Materials Conservation, Western Australian Museum, for conservation treatment. The shells of marine animals, including uninhabited Teredo worm tube, were removed using dental tools, and the wood surfaces gently brushed and rinsed to clean away clinging seabed debris. During this procedure the wood was frequently wetted to prevent surface drying. After cleaning and sampling, a solution of BDH Panacide (a biocide) was applied to the wood surfaces to eliminate any living microscopic organisms and prevent the development of bacteria and fungi during storage. Sterile bandages were then wrapped around each piece of wood and re-soaked with the biocide. Each was wrapped in polythene sheet, sealed with tape, and bound in several layers of protective foam. A further layer of polythene was then sealed around each of the parcels of wood.

Conclusion

The region surrounding Site P and Site T is a formal mooring or lightering site for Galle. The discovery of these anchors indicates a continuity of use of this area. Anchors were designed for holding a vessel's position in mid water rather than alongside the land. In light of this, an anchor represents a means of stopping a ship effectively where there was no mooring available or possible (Nibbi, 1993:11). The variety of anchors discovered in close proximity to each other in Galle Harbour leads one to conclude that a specific type of anchor would be selected according to the mariners' requirements, the ability of a ship to transport the particular anchor type, and the availability of materials, with broken anchors reused as moorings.

Appendix: geological-petrological study of the anchors

by Ananda Gunatailaka, consultant; formerly Professor & Chairman of the Department of Earth Sciences, University of Oman

Large Arab-Indian anchor, GHP 30

The anchor is about 1.5m in length and was fashioned out of a sedimentary rock called a conglomerate. Conglomerates are very coarse-grained rocks made up of one or more clast types. Examination of this anchor, which was displayed outside the Galle Archaeological Museum within the Galle Fort, indicated that the rock is made up of several clast types of various sizes and shapes. The largest clast size is as much as 40mm in length and the smallest size grades down into a sandy matrix in which the larger clasts are embedded. The clasts are angular to well-rounded. These features indicate a very poorly-sorted rock (polymodal grain-sizes), which in geological terms could be described as a polymict conglomerate. The rock is cemented almost exclusively of calcite, which fills up the pore spaces between the grains.

Clast composition: the clasts are dominantly made up of chert and quartz (both mono and polycrystalline grains) of pebble to sand size. In addition to these are clasts of fine sandstone, marl, limstone, shale and dark brown fragments of iron-stained materials. Under the microscope, these brownish grains appear to be ophltlitic in composition (now altering to serpentine). In addition to this, there are occasional felspar grains, shale and trachyte clasts. The matrix is mainly chert and quartz. The rock is cemented by calcium carbonate (calcite) which is the main pore filler. At least three generations of carbonate cement can be seen. The rock can be described as a polymodal or poorly sorted polymict conglomerate.

These rocks are quite common in alluvial fan or fan delta complexes flanking rising mountain fronts or fault scarps (half-grabens). Along both flanks of the mountains of Oman, this author has seen very similar conglomerate formations several hundreds metres in thickness.

Provenance: the author is certain that the above anchor originated in Oman. The chert-ophiolite-fine sandstone (probably turbiditic) clast association in conglomerates is typical of the alluvial fan formations of the Oman Mountain front. In addition, marl, shale and limestone are very common rocks in Oman's mountains. Further, these conglomerate formations are ubiquitous along the mountain front along the Oman coastline. The Oman coastline has been well known since medieval times for its shipbuilding. Even today there are several boatyards building dhows - the most famous of them being the village of Sur on the coast. These conglomerate formations were, and are, within walking distance of the shipyards. Further, it is known that although Omanis used grappling anchors in their ships, they also used stone anchors for mooring their vessels. These observations could be no more than coincidental but the author's many years of geological experience in Oman, and his familiarity with its geology, are the main reasons for his opinion that the anchor had an Omani provenance.

It is certain that this rock type and its composition is not found in Sri Lanka. In fact, the author cannot think of any place in the region excepting Oman, where such a conglomerate has been described.

Four-hole Mediterranean-style anchor, GHP 32

This is a well-laminated sandstone anchor made up of essentially coarse-grained quartz and comminuted shell material. The grains are cemented by CaCO3 (spar calcite). The rock from which this anchor was made is very likely a beach sand that is commonly seen in many coastal areas of the world. The anchor could have come from anywhere.

Broken Arab-Indian anchor, GHP31

This is very much like a beach rock and is made up of mostly shelly material and quartz grains. No bedding or lamination was developed in the rock. It is heavily bored by various marine boring animals, giving the rock a honeycomb-like effect. Such rocks are forming today in many coastal areas of the world. The author has seen such rocks all along the Arabian coastal zone, from Abu Dhabi to Kuwait. It is a heavily bored, shelly, sandstone beach rock.



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